The Scientific Harrovian - Issue 6-1, December 2020 by Harrow International School Hong Kong

VI: Issue VI-1

Scientific Har r ovian Physics and Te c h n o l o g y Biology and Chemistr y Mathematics

Science and Society Har r ow Inter national School Hong Kong

2 Uncited images from Unsplash

About the Scientific Harrovian

The Scientific Harrovian is the Science Department magazine, which provides a platform for students to showcase their research and writing talents, and for more experienced pupils to guide authors and to develop skills to help them prepare for life in higher education and beyond.

Copyright ÂŠ 2020 by The Scientific Harrovian. All rights reserved. No part of this book or any portions thereof may be reproduced or used in any matter whatsoever without express written permission of the p u b l i s h e r, e x c e p t f o r t h e u s e o f b r i e f q u o t a t i o n s i n a b o o k r e v i e w.

MESSAGES

We l c o m e t o I s s u e V I - i o f t h e Scientific Harrovian!

It has been a joy to witness the creation of such a wonderful Sixth Edition of the Scientific Harrovian. This really is a publication for pupils by pupils and so my congratulations and thanks go to all writers, editors and illustrators for their scientific passion and hard work. They have all created something to be proud of and cherish. Extra special thanks have t o g o t o t h e S c i e n t i f i c H a r r o v i a n ’s Editors-in-Chief, Stephenie Chen and Annie Kim. Despite juggling the demands of a busy first term they have never let the Scientific H a r r o v i a n t e a m l o s e t h e i r w a y. I have been inspired by the plethora of articles on the theme of ‘Science in Society’. This theme couldn’t be better suited to a time where society and Science could not be more i n t e r l i n k e d . Wr i t t e n a n d i l l u s t r a t e d f r o m Ye a r 7 t o Ye a r 1 3 p u p i l s , t h e y are all united by their desire to e ff e c t i v e l y c o m m u n i c a t e S c i e n c e t o t h e p u p i l b o d y. W h e t h e r y o u w o u l d l i k e to find the answer to big questions in the article “Science, cosmology and the existence of God” or would like to determine whether psychedelics a r e m o r e ‘ Vo o d o o o r S c i e n c e ’ , t h e r e is something for everyone in this edition. I hope that whichever articles you read or illustrations you admire that you feel as inspired as I have.

Siobhan McCrohan Te a c h e r o f B i o l o g y

T h i s y e a r ’s a r t i c l e s h i g h l i g h t t h e pressing importance of science in society (especially in a world where certain Presidents don’t believe it). Furthermore, we’ve decided to take a new approach - no longer is the Scientific Harrovian the inaccessible magazine of days past - without any i r o n y w h a t s o e v e r, s c i e n c e i s f u n , a n d we’re seeking to make it so. There has also been a newlyi n t r o d u c e d E d i t o r i a l Te a m : A n n i e Kim, Deputy Editor-in-Chief; Isabel C h a u , H e a d D e s i g n e r ; H o i K i u Wo n g , Biology Head Editor; Jasmine Chan, Chemistry Head Editor; Callum Sanders, Physics Head Editor; E d w a r d We i , Te c h n o l o g y H e a d E d i t o r ; a n d J e n n y K i m , M a r k e t i n g D i r e c t o r. I couldn’t be prouder of what everyone has achieved, whether it be the E d i t o r i a l Te a m s p e n d i n g h o u r s p o r i n g over articles and ensuring that the edition is perfect, or all the students that have contributed their incredible writing to this article. Special thanks should go to Annie Kim, who stepped up and coordinated this sub-issue as temporary Editorin-Chief - this sub-issue could not have come into reality without her direction, motivation and passion. Enjoy! Yo u r s s i n c e r e l y,

Stephenie Chen Editor-In-Chief

MESSAGES

We l c o m e ! The theme of Edition VI-i of the Sc ienti f ic Harrov ian is Sc ienc e and S o c i e t y, a n e x t r e m e l y r e l e v a n t t o p i c in this challenging year when science i s m o r e i m p o r t a n t t h a n e v e r. As well as the usual ar ticles by the ver y talented writers of our team, this issue includes some featured a r t i c l e s f r o m t h e Wo r l d M a t h e m a t i c s Championships in which members of the Sc ienti f ic Harrov ian per f orme d ver y well on. It is my first time taking on such a g r e a t r e s p o n s i b i l i t y, s o I w o u l d l i k e t o thank Stephenie for trusting me with the role of Editor-in-Chief for this is sue , and the Sc ienti f ic Harrov ian executive team for helping to make this issue possible. I would also like to thank all our contributors for their hard work and organisation despite being online for a significant part of the term while also juggling internal assessments and universit y applications. T h i s y e a r, o u r t e a m i s v e r y e x c i t e d to introduce the ver y first Scientific Harrov ian Qui z E x travaganz a held n e x t w e e k o n D e c e m b e r 1 8 t h . We h o p e we can make the Sc ienti f ic Harrov ian more engaging for all pupils in the school.

Dear readers, It has been four months since the start of term, and I’ ve witnessed the Sc ienti f ic Harrov ian Is sue VI-i c ome together bit by bit : the planning and research by the writers and the meticulous per fecting by the editors. Of course, I cannot forget to mention our dear illustrators that I’ ve been spamming over email. They have added ex tra flavour and colours to the ar ticles, and also inspired the design of this issue. In this issue, we present to you ten ar ticles from different fields and aspects of science, all with a united t h e m e : “ S c i e n c e a n d S o c i e t y ”. W h i l e p u t t i n g t h e i s s u e t o g e t h e r, I h a v e had the honour of pre -reading the ar ticles, and I can assure you that they will fascinate you.

I hope you enjoy reading this as much as we enjoyed creating it!

It has been a pleasure to be a par t of this issue’s creation. I can’ t wait for you to turn the page!

Yo u r s f a i t h f u l l y,

H o l d o n a n d e n j o y,

Annie Kim

Isabel Chau

Deput y Editor-in-Chief

Head Designer

CONTRIBUTORS THE TEAM

Editor-in-Chief Stephenie Chen Year 13, Gellhorn Deputy Editor-in-Chief Annie Kim Year 12, Wu Head Designer Isabel Chau Year 12, Gellhorn Biology Head Editor Hoi Kiu Wong Year 13, Wu Chemistry Head Editor Jasmine Chan Year 13, Wu Physics Head Editor Callum Sanders Year 10, Shaftesbury Technology Head Editor Edward Wei Year 11, Peel Marketing Director Jenny Kim Year 11, Anderson

CONTRIBUTORS

WRITERS Katrina Cheng Year 13, Gellhorn

Edward Wei Year 11, Peel

Hanson Wen Year 9, Peel

Alyssa Wong Year 11, Anderson

Hoi Kiu Wong Year 13, Wu

Josiah Wu Year 13, Churchill

Joshua Yen Warren Zhu Year 12, Shaftesbury Year 12, Churchill

ILLUSTRATORS Isabel Chau Year 12, Gellhorn

Joy Chen Year 10, Gellhorn

Ethan Lan Year 7, Shackleton

Se Lyn Lim Year 12, Wu

Reika Oh Year 11, Gellhorn

Kayan Tam Year 13, Wu

Emily Tse Year 11, Keller

Callum Sanders Year 10, Shaftesbury

CONTRIBUTORS

EDITORS Haley Chan Year 13, Wu

Joy Chen Year 10, Gellhorn

Iris Cheung Year 12, Gellhorn

Joanna Fung Year 8, Fry

Diya Handa Year 13, Anderson

Catrina Kean Year 12, Gellhorn

Alison Kerr Year 11, Wu

Jonathan Lee Year 12, Peel

Helen Ng Year 10, Gellhorn

Kee Meng Tan Year 12, Churchill

Emily Tse Year 11, Keller

Michelle Yeung Year 13, Keller

FEATURED WRITERS Daniel Kan Year 9, Shaftesbury

Benjamin Law Year 9, Peel

Chloe Levieux Year 11, Gellhorn

Kevin Liew Year 11, Peel

Helen Ng Year 10, Gellhorn

Andrew Wang Year 11, Peel

INDEX Physics and Te c h n o l o g y

Science, Cosmology And The Existence Of God

Will Building A Dys on Sphere Solve The Ear thâ€™s Energy Problems?

J o s h Ye n

A l y s s a Wo n g

Biology and Chemistr y

Ant imatt er And The Ozma Pr oblem

M a t e r i a l S u s t a i n a b i l i t y : H o w To P r o v i d e The Same With Les s ?

Ps y c h e d e l i c s : Vo o d o o Of S c i e n c e?

A p p l i c at i o n Of T h e Hu ma n Mi c r o b i o me

89 Mat hematics

Featured articles f r o m t h e Wo r l d Mat hematics Championships

Ho i K i u Wo n g

Katrina Cheng

Wa r r e n Z h u

Ha n s o n We n

Future Of Farming E d wa r d We i

106

Real Life Application Of Complex Numb e r s

114

G a m e T h e o r y A n d Ho w I t A i d s Ou r Wo r l d To d a y

122

J o s h Na s h A n d H i s C o n t r i b u t i o n To S D G

J o s i a h Wu

Helen Ng, Daniel K an, Benjamin Law

K e v i n L i e w, C h l o e L e v i e u x , A n d r e w Wa n g

Physics and Te c h n o l o g y

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Science, Cosmology and the Existence of God Josh Yen

The existence of god has been one of the most controversial discussions in society, philosophy and science. Whether there is a god or not has significant ramifications on society and would significantly change the way we live. This is why I would like to weigh in on the scientific side of this debate and demonstrate why there is most likely a creator of the universe (a god) given our understanding of cosmology and causation.

PHYSICS AND TECHNOLOGY A simple formulation of the argument: If you have had any past experience with the philosophy of religion, you probably know that what I am referring to in my abstract is what philosophers call a cosmological argument. This is an argument from our understanding of the universe to the existence of a god. While there are multiple formulations of this argument, for the sake of simplicity, I will be using the Kalam cosmological argument, an argument from the finitude of the past. The argument goes as follows: Premise 1 (P1): If the universe began to exist, then the universe must have had a cause Premise 2 (P2): The universe began to exist Therefore, Conclusion 1 (C1): T he universe has a cause [1] Premise 3 (P3): If the universe has a cause, the cause is a god Premise 4 (P4): The universe has a cause (C1) Therefore, Conclusion 2 (C2): The cause is a god. Since this argument is laid out in a deductive syllogism (that of modus ponens), we can see that if the premises are true the conclusion logically follows. In other words, one cannot accept our premises and disagree with our conclusion. Therefore, in this article, I will be defending each of these premises to demonstrate the truth of this argument.

1 â€œKalamâ€? is an Islamic school of thought which formulated this form of cosmological arguments (those from the finitude of the past) 2 The finitude of the past is a concept where the universe is past finite and has a beginning; this is in stark contrast to an infinite past. 3 A deductive syllogism is a way of laying out an argument which makes it such that if the premises are true, the conclusion must be accepted. In the case of this article, while the premises arenâ€™t necessarily defended via a priori methods and should be seen as a fundamentally inductive argument, the use of this syllogism entails that one should argue against the premises, not the conclusions.

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Premise 1: If the universe began to exist, then the universe has a cause

T he first premise of the argument is relatively controversial in the fields of science and philosophy as it is based on the principle of temporal causation. This is the idea that all finite and temporal beings require a cause for their existence. This law undergirds all logical thinking and is a necessary belief for all our pursuits, especially those within science.

A good example of this law would be boiling water. The heat of the fire is the cause or the reason behind the fact that the bonds between water molecules break down and evaporate. It would be scientifically incorrect to claim that the water molecules just evaporated without a cause. This line of reasoning undoubtedly conforms with all our experiences and is the strongest intuition that we have. We know that things must have a cause and there cannot be uncaused phenomena. A further reason which supports the principle of temporal causation is the idea that something cannot come from nothing. This comes in the form of the Latin old saying “ex nihilo, nihil fit”roughly translating to “nothing comes out of nothing.” If this saying stands, all things which

are contingent or subject to time must require a cause. The change of a state of absolute nothingness to a state with something is impossible without an external cause. This concept can be rearranged into a simple deductive syllogism: P1: If something cannot come from nothing, all things that come into existence must come from something P2: Something nothing

cannot

come

from

C1: Therefore all things must come from something P1 of this argument appears to be self-evident and does not require much explanation. There exists either something, or there exists nothing. Hence, if something cannot come out of nothing, then it follows that something must require an antecedent cause.

4 This is to be contrasted with causation simpliciter, the idea that every single being which exists must have a cause. 5 Now it is clear to note that the theist does not believe in ex nihilo creation simpliciter. Instead, he is just claiming that there are no physical entities. The reason for this is simple, a god is not physical and is a transcendent being. Hence, when a theist uses ex nihilo, he is referring to the idea that there was no physical entities prior to the creation.

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Hence, the crux of this argument depends on the strength of P2, which is undeniable. Throughout the history of mankind, no one has ever experienced an ex nihilo (out of nothing) creation (in the strict sense of the term). For if anyone were to point to anything in the world and suggest that it was self-caused, one would rightfully dismiss him as insane. For example, if an explosion occurred in the schoolâ€™s Science department, surely we would be looking for a cause of such a tragedy instead of suggesting that the explosion just appeared ex nihilo. Despite this apparent strength, a physicist named Lawrence Krauss has suggested that due to developments in quantum physics, we have observed particles that come into being without

an apparent cause and appear to support the hypothesis of an ex nihilo creation [2]. While this approach has been growing in popularity, especially when some scientists start realising the philosophical implications of a finite universe, such a rebuttal, fails to gain traction within academia since Kraussâ€™ hypothesis egregiously overlooks the sea of quantum energy that these particles are fluctuating out of. In reality, this is no ex nihilo causation, instead it is just particles fluctuating from a state of quantum energy. With this in mind, it appears that the first premise of our argument is well defended and supported, allowing us to move onto the more controversial premise - whether or not the universe has a beginning.

PHYSICS AND TECHNOLOGY Premise 2: The Universe Began to Exist Historically, the second premise of the argument has been defended predominantly by philosophical arguments. In this case, I will be approaching this premise from the perspective of science, more specifically the Big Bang hypothesis and the Second Law of Thermodynamics. Under the Big Bang hypothesis, space, time and matter came into existence a finite time ago. In this model, the universe is currently growing in size and expanding into nothingness. This hypothesis is supported by two pieces of evidence, Cosmic Microwave Background Radiation (CMBR) and red-shift. CMBR is a form of radiation which is present in low amounts throughout the entire universe. This suggests that in the past, the universe was dense and “hot”, pointing towards an explosion of energy from a singularity. Over time, this energy “spread out” through the universe leading to this current state of low energy. Red-shift also provides good evidence for the expanding model of the universe. Red-shift is the concept that as celestial bodies move away from each other or towards each other, the wave frequencies of their light are changed. This leads to either red or blue shifts respectively. Due to universal red-shift that we observe in celestial bodies, we can infer that stars and galaxies are moving away from each other. This suggests that the universe is expanding from an initial singularity in the finite past. These observations have contributed heavily to the development of the Friedmann-Lemaitre-RobertsonWalker spacetime model which shows that given the current understanding of universal expansion, we can trace the boundary of spacetime back to a finite point in the past. Physicist P.C.W. Davis comments on such a model as follows, “If we extrapolate this prediction to its extreme, we reach a point when all distances in the universe have shrunk to zero. An initial cosmological singularity therefore forms a past temporal extremity to the universe. We cannot continue physical reasoning, or even the concept of spacetime, through such an extremity. For this reason

PHYSICS AND TECHNOLOGY

most cosmologists think of the initial singularity as the beginning of the universe. On this view the big bang represents the creation event; the creation not only of all the matter and energy in the universe, but also of spacetime itself [3].” Apart from this relatively empirical approach to the beginning of the universe, a finite universe is also defended mathematically by theoretical physicists Arvind Borde, Alan Guth, and Alexander Vilenkin in their paper “Inflationary spacetimes are not past-complete [4]”. In this paper, they demonstrate that “a cosmological model which is inflating or just expanding sufficiently fast must be incomplete in null and timelike past directions [5]”. This essentially means that in any expanding universe, it is inevitable that one reaches a singularity in the past. The universe cannot, mathematically, contract for infinity, hence there must have been a beginning. Since our universe is expanding, it follows that there must have been a beginning. Now, let us turn to the Second Law of Thermodynamics. The Second Law of Thermodynamics also states that the entropy of a closed system increases irreversibly. When the entropy of a system reaches its maximum, we arrive at what scientists like to call “the heat death” of the system. In such a state, there is no longer any usable energy and the universe would, quite literally, die, as nothing can be done or changed. Now the problem arises for the proponent of an infinite past. If the universe has been around for past infinity, why are we not currently at heat death? How are we still alive and experiencing the movement of energy and other phenomena that would be impossible in a system with maximum entropy? Since we have established from the Big Bang and the Second Law of Thermodynamics that the universe must have a beginning, it follows that the universe is past finite. This is the idea that one cannot trace the causal/ temporal chain of the universe back for infinity, since there would be a point where the chain stops.

Conclusion 1: The universe has a cause Since this argument is deductively valid and the premises are true (as I have shown above), it logically follows that the universe must have a cause for its existence.

6 Entropy is a complex idea but is best explained as the unusable thermal energy within a system. If a system reaches maximum entropy, the system becomes “heat dead” and nothing can be carried out in such a system

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Premise 3: If the universe has a cause, the cause is a god However, our Conclusion 1 raises an instant question: what is the nature of this cause, and what are its attributes?

In order to elucidate these characteristics, I will split them into primary natures and secondary natures. Primary natures

state of physical nothingness, it follows that it must exist timelessly. For there was no change in the state of affairs in

are aspects that are directly deduced from the argument, and secondary natures are aspects that canâ€™t be directly deduced from the argument yet can be reasonably inferred.

regards to this cause.

The three primary natures are timelessness, transcendence and a personal connection with the creation. I will spend some time here to elucidate each point. Timelessness: What does it mean to be timeless? This is a complex question and has been a matter of intense philosophical debate, but for the sake of simplicity, I would define timelessness as a property which shows that a being is not restricted by the passing of time or time does not act on such a being. With this in mind, how do we know that our cause of the universe is timeless? Since there were no physical states of affairs or change before the existence of the universe, it was a period of physical nothingness, we can state that this period is timeless. Yet since this cause existed prior to the universe in this

Of course, this changed when the cause caused the universe into existence. At this point, one can say that this cause is now in a temporal relationship with the universe and is no longer timeless. Yet, for all intents and purposes, we can safely conclude that this cause was timeless sans creation [6]. Transcendence: Why must this cause be transcendent? This is quite selfexplanatory. Since the cause existed prior to the universe, it must transcend the universe. Personal: Finally, we know that the cause must be personal. Due to the nature of causation, the cause is always related to the effect (either directly or indirectly). Since we have no evidence to suggest that anything physical existed prior to the universe, it is safe to assume that there was nothing prior to the universe. When we return to our understanding of direct and indirect causation, we can know that indirect causes only happen when the causal antecedent is causing

7 At this point, it is important to note that these are not scientific observations or empirical demonstrations of this cause. Instead, these are philosophical conclusions given the situation that we are exposed to.

PHYSICS AND TECHNOLOGY another being or entity and the indirect cause comes as a side effect. Since there are no beings sans the universe, we can see that this cause cannot be indirect and has to be a direct personal cause of the universe. The secondary attributes include free will, immense power and immense knowledge. Free will comes from the question of why there is something rather than nothing. Since there are no physical laws (that we know of) before the universe’s creation, there appears to be nothing “determining” the cause. There is no reason why the cause had to cause the universe; it could have done otherwise. Why this universe instead of another? Why did this specific universe come into existence instead of another one with vastly different laws of nature? Surely there is nothing necessary about the conditions in the world that we live in. Hence, it appears that this cause does have free will. The attribute of immense power originates from the fact that it created everything in existence, while it is possible for some “butterfly effect” cause, it is more probable that

the creator of the universe is immensely powerful. Great knowledge follows on from immense power. If something created the entire universe, it implies that it knows quite a lot. So let us summarise these attributes and see what it can tell us about the nature of this cause. As we have established, the primary attributes are timelessness, transcendence, and a personal and direct relation with the cause. The secondary attributes are free will, immense power and immense knowledge. Of course, if one were to claim that this directly proves the existence of the God of classical theism or the Christian God, he would be insane. But when we look at these attributes, it is undeniable that they point towards a theistic explanation of the universe instead of an atheistic one. For it would be an extreme form of atheism, perhaps one not worthy of the name of “atheism”, to suggest that there exists a personal, transcendent, powerful, timeless cause of the universe.

Conclusion 2: The cause is a god Since we know that the universe does have a cause (Conclusion 1), it follows from Premise 3 that the universe’s cause is a god. I would like to make it clear that this is not an argument for the Christian God, nor is it an argument for monotheism. However, it does point to a cause which has theistic properties.

8 This is the idea that a small cause can lead to a large effect (latter on in the causal chain)

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Two objections:

Any argument about the existence of a god is expected to raise controversy and discussion. Especially when the argument is so simple, yet so powerful. Hence, I feel that I would be doing the Kalam a disservice if I fail to discuss two of the most common objections.

1) What caused a god?

Although the objection “what caused a god?” is a rather unfounded argument with little to no reason backing it, it is Dawkins’ self-proclaimed “knock-down argument” of cosmological arguments and therefore requires a quick shout out before it can be dismissed with a quick exclamation of “You’ve gotta be kidding me!” The reason why we can dismiss this rebuttal easily is due to the fact that the objector does not understand the Kalam cosmological argument. If we were saying that all things that exist require a cause, then this objection would be valid. Yet this is not what I have been defending. If you look at the fine-print of any cosmological argument, it is clear that this is not what we are referring to when we raise a causal principle like the principle of temporal causation When we raise cosmological arguments, we have a very specific goal in mind. Instead of defending the need for causation simpliciter, one only argues that things which have temporal relationships require causation. It does not apply to timeless or past infinite beings. Therefore, it can only be concluded that such a rebuttal is aimed at a strawman which no theist has ever tried to defend in the past.

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2) Does the nondeterministic nature of quantum mechanics undermine classical ideas about causality?

Due to recent developments in quantum mechanics, some people have suggested that traditional ideas about deterministic causes do not apply. They would suggest that the Kalam is incompatible with non-deterministic causation and would fail. There are a few responses that a Kalam defendant can turn to. Firstly, it appears that causes do not need to be deterministic to be causes. Even in a nondeterministic universe, causation is still very much real. Since a “cause” is defined as something which leads to another event or causes a change, it appears that even if something is completely non-deterministic, it can still be regarded as a cause.

9 relating to the philosophical doctrine that all events, including human action, are a determined by causes regarded as external to the will.: “a deterministic theory”

PHYSICS AND TECHNOLOGY One can take a random number generator and say that it is the cause of the picked number even though it is random. Furthermore, under the assumption that we have free will, we are technically not â€œdeterminedâ€?. Despite this freedom, we can act as causes of certain effects. Us swinging a racket would lead the tennis ball to fly back to the other side of the court. Hence, objects do not need to be deterministic to be a cause. Secondly, it appears that even quantum physics abides by certain causal rules. Although some physicists would present the idea that the quantum realm is completely random and is a mess of particles and energy fluctuating in and out of existence, Robert Koons explains that causal relations exist in his book Realism Regained: An Exact Theory of Causation, Teleology and the Mind [7]:

According to the Copenhagen version of quantum mechanics, every transition of a system has causal antecedents; the preceding quantum wave state, in the case of Schrodinger evolution, or the preceding quantum wave state plus the observation, in the case of wave packet collapse. Therefore, it would appear that causation is very much existent in quantum mechanics even if they are not strictly deterministic. With these rebuttals to objections that arise from quantum physics, we can reach the conclusion that the principle of temporal causation appears to remain intact and there is no knockdown or significant argument which can be raised from the quantum physics side of things.

PHYSICS AND TECHNOLOGY Bibliography

Final Thoughts: Since both of these arguments against the Kalam have been shown to be vacuous, it appears that one can rationally support the premises of our argument. Turning back to our formulation, since this is a deductive argument with sound premises, we can see that the conclusion logically follows; that there is an immensely powerful, transcendent, personal cause for the universe — a god.

[1] Craig, William Lane. The Kalam Cosmological Argument. Wipf and Stock, 2007. [2] Krauss, Lawrence Maxwell. A Universe f ro m N o t h i n g. S i m o n & S c h u s t e r, 2 0 1 2 . [ 3 ] P. C . W . D a v i e s , “Spacetime Singularities i n C o s m o l o g y, ” i n T h e Study of Time III, ed. J . T. F r a s e r ( B e r l i n : S p r i n g e r Ve r l a g , 1 9 7 8 ) , pp. 78-9. [4] Borde, A. et al. “Inflationary spacetimes are not past-complete.” Physical Review Letters ( 2 0 0 1 ) : n . Pa g. [5] Ibid. [6] Craig, William Lane. Time and Eternity: Exploring God’s Relationship to Time. C r o s s w a y, 2 0 0 1 [7] Koons, Robert C. Realism Regained: An Exact Theory of C a u s a t i o n , Te l e o l o g y, and the Mind. Oxford University Press, 2000.

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Will Building a Dyson Sphere Solve Earthâ€™s Energy Problem? Alyssa Wong

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Earth has an energy problem. But for most of human history, energy consumption was modest [1]. People relied on caloric energy from the food they consumed or on animal power to perform daily tasks. Burning biomass such as wood was the biggest source of energy. Then came the Industrial Revolution in the 1800s and the rise of the new Holy Trinity of energy: coal, natural gas, and petroleum, all of which are non-renewable fossil fuels. Our current annual global energy consumption is estimated to be 580 million terajoules –– roughly equivalent to the energy we would use if all 7.5 billion of us boiled 70 kettles of water per hour every day for a year [2, 3]. 80% of this energy comes from fossil fuels, a leading source of global warming pollution, damaging the planet at almost every stage [4]. The extraction of fossil fuels, done mostly through mining or drilling, damages land, threatens the health and safety of miners and causes water and air pollution. The refining and purifying of fuels into a usable state leaves excess waste material disposed of in ways detrimental to the health of the environment and the community. The transportation of fossil fuels over long distances also generates its own pollution and may result in disastrous accidents such as oil spills and gas leaks. And the burning of fossil fuels releases soot, the health consequences of which include chronic bronchitis and aggravated asthma, as well as sulfur dioxide and nitrogen oxide, leading to acid rain. Most significantly, it releases carbon dioxide, a greenhouse gas that traps heat in the atmosphere and causes global warming. The hotter, drier climate has driven both the Australian bushfires and California wildfires –– we are literally setting the planet on fire.

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But the solution to Earthâ€™s energy problem might not come from the Earth itself. At any moment, the sun emits about 3.86 x 10 26 watts of energy - 7 x 10 17 times more energy than we need [5]. Weâ€™re just not harnessing it. Yet. In 1960, British-American theoretical physicist Freeman Dyson first speculated about Dyson spheres, hypothetical megastructures that encircle a star to capture a large percentage of its power output [6]. A Dyson sphere would not be a literal solid sphere enclosing the sun, as the immense tensile strength needed is physically impossible to achieve with our current technologies. A structure like that would also be liable to drift and crash into the sun [7]. Instead, if we were to build a Dyson sphere, we would most likely use a Dyson swarm model, which is a collection of solar panels situated in orbit around the sun (See Fig. 1) [7, 8].

Fig 1. Dyson swarm 3D model Image by Aicrovision ( Tu r b o S q u i d ) h t t p s : / / w w w. turbosquid.com/3d-models/ dyson-swarm-3d-model-1369830

These solar panels would be very large lightweight mirrors, concentrating solar radiation down on focal points (heat engines combined with solar cells) where it would be transformed into useful work and beamed across space for use elsewhere [8]. They would need to operate without repairs for long periods of time and be cheap to produce, most likely made of polished metal foil bound to some supports (See Fig. 2) [9].

Fig. 2 Solar panel 3 D model I m a g e b y A i c r o v i s i o n ( Tu r b o S q u i d ) h t t p s : / / w w w. t u r b o s q u i d . c o m / 3 d models/dyson-swarm-3dmodel-1369830

PHYSICS AND TECHNOLOGY The sun is massive, so in order to surround it with solar panels, we would need to disassemble an entire planet. The easiest victim would be Mercury –– it’s the closest to the sun, has no atmosphere, only has about a third of the surface gravity of Earth, and is composed of 30% silicate and 70% metal, mainly iron or iron oxides, materials that will be used for the swarm [8, 9]. The initial energy generating source will be a 1 km 2 array of solar panels, constructed on Mercury itself and then launched into space [8]. These will provide the energy to run miners which strip mine the planet’s surface and refiners, extracting valuable elements and fabricating them into swarm panels [9]. This forms a feedback loop, where the material removed will be made into solar captors that generate energy, allowing more material to be removed. 1/10ths of all the energy will be used to propel material into space. We can take advantage of Mercury’s low gravity to use mass-drivers such as railguns to launch the panels at high speeds into space –– much more efficient than using rockets. The entire process would be carried out by an army of automated robots overseen by a small group of human controllers [8, 9]. Assuming the overall efficiency of the solar captors is 1/3, that it takes five years to process the material into solar captors and place them in the correct orbit, and that half of the planet’s material will be suitable to construct solar captors, Mercury itself will be completely disassembled in 31 years and 85 days, thanks to exponential growth. The power available increases initially in five-year cycles, which gradually smooth out to become linear on the log scale (See Fig. 3) [8].

Fig 3. Power available during the disassembly of Mercury Image by Stuart Ar mstrong and Anders Sandberg http://aleph.se/papers/ Spamming%20the%20universe.pdf

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Illustration by Callum Sanders

PHYSICS AND TECHNOLOGY

Harnessing even a tiny fraction of the sun’s energy using the Dyson sphere would give us the energy for projects such as terraforming planets, forming space colonies, or building other megastructures such a stellar engine to move our star, and thus the solar system, through the galaxy. So if building a Dyson sphere can solve our energy problem and offer almost unlimited energy from our current energy consumption standpoint, why haven’t we done it yet? Well, because it’s impossible. For now, at least. The Dyson sphere was originally conceptualised as a way for an intelligent alien civilisation to satisfy their energy needs after having gained the ability to use and store all of the energy available on its planet, meaning the aliens are already a Type 1 civilisation on the Kardashev scale. The Kardashev scale is a method of measuring technological advancement based on the amount of energy a civilisation can use [10]. A Dyson sphere is an indicator of a transition to a Type 2 civilisation, which can use and control energy at the scale of its planetary system, and an eventual evolution to a Type 3 civilisation, which can control energy at the scale of its entire host galaxy [10]. We haven’t even reached the threshold to become a Type 1 civilisation yet, so trying to build a megastructure around the sun is probably not a good idea.

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Building a Dyson sphere would be the largest, most ambitious project undertaken by humanity and would require global cooperation on a level we just haven’t reached yet. We also don’t yet have the technology to achieve some of the more ambitious steps necessary.

The plan involves mining Mercury until the planet is entirely disassembled. The deepest mine on Earth, the Mponeng Gold Mine, has a depth of 4 km below the surface [11]. The radius of Mercury is 2,439.7 km [12]. Additionally, Mercury is supposed to be mined mostly by robots, which we don’t even have in mines on Earth yet [11]. There’s also the issue of Mercury’s unusable mass, which becomes debris [11]. Transmitting power back to Earth poses another problem. Wireless transmission of electricity is possible, but not exactly easy. Microwaves can transmit electricity, though the furthest distance scientists have been able to do so is 148 km, with most of the energy being lost [11]. Lasers are another possibility yet similarly have limited distance. Unfortunately, we currently are not

able to transmit any of all that glorious solar energy across the 102.1 million km between Mercury and Earth [13]. We have far from exhausted the solutions to our energy problem right here on Earth. In 2019, only around 11% of global primary energy came from renewable technologies, 7% being hydropower, one of our oldest and largest sources of low-carbon energy [14]. The World Wildlife Federation’s 2011 Energy Report states ‘it is technically possible to achieve almost 100% renewable energy sources within the next four decades’, with the major sources being wind, solar, biomass and hydropower. It estimated that a million onshore and 100,000 offshore wind turbines could meet a quarter of the world’s energy demand by 2050 [15].

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When energy consumption is narrowed down to just electricity, which is easier to decarbonize as it is less reliant on oil and gas, around a quarter of energy comes from renewables [14]. These numbers can still be increased. Although there is concern that the deployment of renewables will result in higher electricity prices, research has shown this doesnâ€™t have to be the case. Energy storage is swiftly evolving and growing cheaper, meaning an energy grid run entirely on renewable energy up to 95% of the time is an increasingly realistic idea [16]. If renewables alone cannot save the planet, we can look to nuclear energy, which still poses a risk of radioactive contamination and dangerous nuclear

waste, but has a small land footprint and low CO 2 emissions, allowing it to eventually replace fossil fuels at a low cost [17]. While uranium, the fuel most widely used for nuclear fission, is not technically renewable, existing uranium from U-mine sites and existing spent fuel in fast reactors provide sufficient uranium fuel to produce 10 trillion kWh/year for thousands of years, making it a sustainable energy source [18]. Uranium extracted from seawater is replenished continuously, so if seawater extraction production costs fall and the source of uranium changes from mined ore to seawater, nuclear energy would also become a renewable energy source [18].

PHYSICS AND TECHNOLOGY Will building a Dyson sphere solve Earthâ€™s energy problem? No. But innovation in order to improve renewable energy technology, a push to increase sustainable energy consumption, and a transition to a green economy will. Once weâ€™ve done all that, building a Dyson sphere may no longer be an impossible concept, but rather the logical next step to open up limitless possibilities.

Photo by Isabel Chau

PHYSICS AND TECHNOLOGY

Bibliography

[ 1 ] “ E a r l i e s t E n e r g y. ” E a r l i e s t E n e r g y | E M E 8 0 3 : A p p l i e d E n e r g y P o l i c y, Penn State College of Earth and Mineral Sciences, h t t p s : / / w w w. e - e d u c a t i o n . p s u . e d u / eme803/node/502#:~:text=Prior%20 to%20that%2C%20early%20 people,an%20important%20source%20 of%20heat. [ 2 ] “ Te r a j o u l e s o f E n e r g y U s e d . ” T h e Wo r l d C o u n t s , h t t p s : / / w w w. t h e w o r l d c o u n t s . c o m / challenges/climate-change/energy/ global-energy-consumption/story [ 3 ] G r a y, R i c h a r d . “ T h e b i g g e s t e n e r g y c h a l l e n g e s f a c i n g h u m a n i t y. ” B B C Future, BBC, 13th March 2017, h t t p s : / / w w w. b b c . c o m / f u t u r e / article/20170313-the-biggest-energychallenges-facing-humanity [ 4 ] “ T h e H i d d e n C o s t s o f Fo s s i l Fuels.” Union of Concerned Scientists, Ju l 1 5 , 2 0 0 8 , h t t p s : / / w w w. u c s u s a . o r g / resources/hidden-costs-fossilfuels#:~:text=Burning%20fossil%20 fuels%20emits%20a,the%20 environment%20and%20public%20 health.&text=Acid%20rain%20is%20 formed%20when,precipitation%20 that%20is%20mildly%20acidic [ 5 ] “ T h e S u n ’ s E n e r g y. ” T h e U n i v e r s i t y o f Te n n e s s e e I n s t i t u t e o f Agriculture, h t t p s : / / a g. t e n n e s s e e. e d u / s o l a r / Pa g e s / What%20Is%20Solar%20Energy/ S u n % 2 7 s % 2 0 E n e r g y. a s p x [6] Mann, Adam. “What Is a Dyson Sphere?” Space.com, August 01, 2019,

h t t p s : / / w w w. y o u t u b e . c o m / watch?v=pP44EPBMb8A&t=472s

[10] Knapp, Adam. “Kardashev scale.” W i k i p e d i a , W i k i m e d i a Fo u n d a t i o n , October 18, 2020, https://en.m.wikipedia.org/wiki/ Kardashev_scale [ 1 1 ] “A F e w M o r e N o t e s O n T h e Impracticality Of Building A Dyson S p h e r e . ” Fo r b e s , Fo r b e s M e d i a , L L C , April 18, 2012, h t t p s : / / w w w. f o r b e s . c o m / s i t e s / alexknapp/2012/04/04/afew-more-notes-on-theimpracticality-of-building-a-dysonsphere/#5b1be47f31ae [ 1 2 ] Wi l l i a m s, D av i d R . “ M e rc u r y Fa c t Sheet.” NASA, 27 September 2018, https://nssdc.gsfc.nasa.gov/planetary/ factsheet/mercuryfact.html [13] “How far is Mercury from Earth? Accurate distance data.” The Sky Live, https://theskylive.com/how-far-ismercury [ 1 4 ] R i t c h i e , H a n n a h a n d R o s e r, M a x . “ R e n e w a b l e E n e r g y. ” O u r W o r l d i n Data, 2017, https://ourworldindata.org/ renewable-energy [ 1 5 ] “ I s I t Po s s i b l e f o r t h e Wo r l d t o Ru n o n Re n e w a b l e E n e r g y ? ” Knowledge@Wharton, Wharton School of the Univer sity of Pennsylvania, A pr 23, 2015, https://knowledge.wharton.upenn. edu/article/can-the-world-run-onrenewable-energy/

h t t p s : / / w w w. s p a c e . c o m / d y s o n - s p h e r e . html

[16] “GE’s North American Studies Show No Hard Limit to Renewables on a Grid System.” GE News, May 23, 2016,

[ 7 ] D v o r s k y, G e o r g e . “ H o w t o b u i l d a Dyson sphere in five (relatively) easy steps.” Sentient Developments, March 20, 2012,

h t t p s : / / w w w. g e . c o m / n e w s / p r e s s releases/ges-north-american-studiesshow-no-hard-limit-renewables-gridsystem

h t t p : / / w w w. s e n t i e n t d e v e l o p m e n t s . com/2012/03/how-to-build-dysonsphere-in-five.html

[17] “3 Reasons Why Nuclear is Clean and Sustainable.” Office of Nuclear E n e r g y, U n i t e d S t a t e s D e p a r t m e n t o f E n e r g y, A p r i l 3 0 , 2 0 2 0 ,

[8] Sandberg, Anders and Ar mstrong, Stuart. “Eternity in six hours: intergalactic spreading of intelligent l i f e a n d s h a r p e n i n g t h e Fe r m i p a r a d o x ” Future of Humanity Institute, Oxford University Philosophy Department, 2012, http://aleph.se/papers/Spamming%20 the%20universe.pdf [9] Kurzgesagt - In A Nutshell. “How to Build a Dyson Sphere - The U l t i m a t e M e g a s t r u c t u r e . ” Yo u T u b e , 2 0 Dec 2018,

h t t p s : / / w w w. e n e r g y. g o v / n e / a r t i c l e s / 3 reasons-why-nuclear-clean-andsustainable [18] Conca, James. “Is Nuclear Power A Renewable Or A Sustainable Energ y S o u r c e ? ” Fo r b e s , Fo r b e s M e d i a , L L C , Mar 24, 2016, h t t p s : / / w w w. f o r b e s . c o m / s i t e s / jamesconca/2016/03/24/is-nuclearpower-a-renewable-or-a-sustainableenergy-source/#1d8e1814656e

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Antimatter and The Ozma Problem Hoi Kiu Wong

Introduction The Ozma Problem was something that lingered in the back of my mind ever since I was first introduced to it. I remember sitting in the classroom near the end of the school year when Dr Daniel, my Year 9 Physics Teacher, decided to go beyond the specification in the Section of Astrophysics and led the class into a whole new world of Quantum Physics. Back then, I remember being confused about the entire idea; however, I have come to realise that it is important for us to find out more about Particle Physics and the Quantum world, as the knowledge we can acquire from it can help us understand more about the nature of the Universe that we live in, as well as the beginning of it. In understanding Particle Physics, we can turn towards understanding the Ozma Problem and how it was solved, which I will delve into in this article.

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Illustration by Se Lyn Lim

PHYSICS AND TECHNOLOGY

The atom Whether you have or have yet to enter the world of Quantum Physics, you may have learnt that the Atom is defined as the ‘smallest unit of matter’. In fact, the word ‘atom’ means ‘indivisible’ in Greek, as it was previously known that atoms cannot be divided into anything tinier [1]. However, we now know that we can go smaller than the atoms, to the subatomic particles - protons, neutrons and electrons [2] - which are made up of even smaller particles known as quarks and leptons [3]. Protons and neutrons are made of two types of quarks: ‘up’ quark and the ‘down’ quark. These quarks have electrical charges that are fractions of the proton’s charge (an ‘up’ quark has ⅔ positive charge and a ‘down’ quark has ⅓ negative charge). A proton is made up of two ‘up’ quarks and one ‘down’ quarks (⅔ + ⅔ -⅓ = 1) so overall the charge adds up to +1, whereas a neutron is made up of two ‘down’ quarks and one ‘up’ quark (⅔ -⅓ -⅓ = 0) which gives the neutron a neutral charge (See Fig. 1) [4]. The electron (a lepton), the up quark, and the down quark (quarks), which are all fermions, are probably the most well known out of the elementary particles. It is through decades of scientific research and, in particular, the research at CERN with the Large Electron Positron (LEP) collider allowed scientists to discover and learn more about these elementary particles [4].

Fig 1. The sets of up quarks and down quarks in a proton (left) and in a neutron (right) Source: Wikimedia Commons

PHYSICS AND TECHNOLOGY In the LEP, positrons and electrons were accelerated around the 27-kilometre circumference of the collider and collided with one another when they reached the same point at the same time. This caused an annihilation to occur (as matter is colliding with antimatter). This annihilation was the key moment for scientists, as the goal was to observe in detail what was released in the aftermath of the collision. To do this, the Collider was equipped with four detectors, built around the four collision points within underground halls. They were capable of registering the particles by their energy, momentum and charge, thus allowing physicists to tell what particle reaction happened and what elementary particles were involved [17]. Many of these emergent elementary particles from the annihilation were unknown before the LEP was built; for instance, the two heavier versions of the electron (the ‘muon’ and the ‘tau’), the two heavier versions of the up quark (the ‘charm’ and ‘top’), as well as the two heavier versions of the down quark (the ‘strange’ and the ‘bottom’) [4]. These newly discovered particles were also revealed to have anti-versions of themselves.

Fig 2. The Standard Model of Elementary Particles. Source: Wikipedia

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The LEP was dismantled in 2001 and was replaced by the Large Hadron Collider (LHC), which is the world’s largest and highest-energy particle collider and the largest machine in the world. The name might sound familiar to you because recently in 2012, it became well known for discovering the Higgs Boson [18]. The discovery of the Higgs Boson is particularly fascinating because, in the 1970s, scientists found out that electricity, magnetism, light and certain types of radioactivity are all manifestations of a force called the electroweak force. The equations detailing the electroweak force correctly describes its force-carrying particles: the photon, the W bosons and Z bosons. All of these emerge with no mass, which is correct for the photon, but not for the W and Z bosons, whose masses are approximately 100 times that of a proton. It is later when theorists Robert Brout, François Englert and Peter Higgs solved the problem. They proposed that W and Z bosons interact with an invisible field, which is now called the ‘Higgs field’. After the Big Bang, the Higgs field was zero, but as the universe cooled and expanded, the field grew, which meant that any particle interacting with it would acquire mass (The Higgs Effect). The more the particle interacts with this field, the heavier it becomes. Photons, as they don’t have a mass, don’t interact with it. The Higgs boson in turn became the associated particle of the Higgs field [19].

Fig 3. Collision at the LHC that produced a Higgs Boson and a Z Boson. The two grey projections represent the particles that decayed from a bottom and an anti-bottom quark, which was likely to have decayed from the Higgs Boson. The green lines represent electrons and positrons, which likely decayed from a Z boson. [20] Source: Thomas McCauley ©2018 CERN (https://cds.cern.ch/ record/2642472?ln=en)

Therefore, discovering antimatter and using it in theories and experiments are fundamental in discovering how the universe began, and the nature of it at a quantum scale.

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Nature of the universe

Einstein’s theory of relativity reveals the interconnection between energy and matter, perfectly shown in his famous equation E=mc 2 . It shows how energy can congeal itself into matter, and in reverse, how matter can turn into energy. The nature of the universe can be further explained when Einstein’s theory is combined with Newton’s Laws of Motion. Take a box for example. To move the box, you have to exert a force onto it, and this resultant force will cause it to accelerate in the direction of the force. This acceleration, as it depends on the force, also depends, in proportion, on the mass of the box. According to Newton’s Laws of motion, if a body is stationary and you apply a force on it for a second, then the speed will increase by some amount. If you apply the same force on the same body again, then the body will increase in speed by the same amount. However, in Einstein’s theory of relativity, this change in speed alters - the next push will increase its speed less than what it did on the first push. If the body is travelling near to the speed of light, pushing it would increase the speed by a negligible amount [4]. Therefore, Newton’s Laws of motion are only

accurate for day to day motion, not in the situation where particles are moving in an accelerator at high relativistic speeds. In contrast to Newton’s Laws of Motion, Einstein’s theory states that the mass of a body increases the faster it travels. Near to the speed of light, its mass becomes infinite. Hence, it is impossible to accelerate the object to the speed of light [4]; light is the only thing that can reach the speed of 299,792,458 metres per second [5]. Take a moving particle. It has energy congealed in its matter, and energy in its motion, which is known as its kinetic energy. The total energy E of the moving particle is not the sum of these two forms of energy, but the square root of the sum of the square of the energy of motion pc (product of momentum and speed of light) and the square of the energy in its mass mc 2 . This may seem familiar to you, as this applies Pythagoras’ theorem. The length of the hypotenuse is proportional to the energy of the moving particle (See Fig. 4) [4].

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Fig 4. Conflation of Einstein’s theory of Relativity with Pythagoras’ theorem. The amount of energy of a body is the square root of the sum of the s q u a r e o f t h e e n e r g y o f t h2 e b o d y w h e n s t a t i o n a r y, m c , and the square of the energy of its motion, pc. [4] Source: Wikimedia Commons This means that a photon travelling at the speed of light, with no mass, has energy due to its motion. As the law of the conservation of energy states, energy cannot be created nor destroyed but can be transferred from one form to another. This shows how the energy of a photon can be transformed into energy trapped in matter. But how is it possible for an electron with a negative electrical charge to come from the energy of photons, which has no electric charge? Under the principle of charge conservation, the only way is that a positron, the anti-version of the electron, is also made. Scientists believe that this was what happened right after the Big Bang, the birth of the universe - light consisting of massive amounts of energy congealed into pieces of matter and antimatter, and when matter and antimatter meet, they annihilate one another, which in turn releases energy. Hence, Einstein’s theory of relativity provided us with the key into the world we live in as well as the one into the antiworld; now, we just need to find the lock [4].

We know that light is made up of photons (quanta of electromagnetic radiation) and the energy of each photon is the product of Planck’s constant and the frequency, E=hf. In an atom of an element, there are discrete and unique energy levels due to the number of quantum waves that can fit into a ‘loop’. Therefore, when electrons move from a high energy level to a lower energy level, the discrete energy difference between the two levels is released in the form of photons, which give out a specific wavelength, and in turn, a specific colour. The colour emitted is unique for each element. This atomic spectrum can be observed by adding the element into a flame and looking at the light through prisms or diffraction grating. In 1896, Peter Zeeman, the Dutch spectroscopist, noticed that when powerful magnets were placed near his samples, the yellow lines emitted by the sodium changed slightly. The yellow lines changed from being sharp and defined into broad. It was later discovered that the broadening lines were actually due to a separation of one line into multiple lines. Why did this happen?

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The electron spin

This is because the electron has its own magnetism; in other words, the magnetic field interacts with the magnetic dipole moment that is associated with its orbital angular momentum [13]. This in turn affects the energy of the sodium samples (each of the levels split into substates of equal energy [14]), which results in an alteration of the atomic spectra. It has effectively been shown that an electron can act as a small bar magnet with a north and south pole and that it has an intrinsic rotary motion known as ‘spin’, which can orientate itself clockwise or anticlockwise in a magnetic field. It’s important to note that spin is an ‘intrinsic rotary motion’ because an electron, in reality, is not a ball but an infinitely small point that cannot spin. Spin is an odd physical phenomenon that is still challenging among physicists to explain. It is like the spin of a planet in that it gives a particle angular momentum and a small magnetic field known as a magnetic moment; however, due to the size of subatomic particles like the electron, its surface would have to be moving faster than the speed of light to produce the measured magnetic moments (which is impossible). Moreover, spin is quantised, so only certain discrete spins are allowed. This can be demonstrated using the SternGerlach experiment [15] (See Fig. 3).

In the Stern-Gerlach experiment, a beam of silver atoms is ejected into an inhomogeneous magnetic field. According to classical physics, it is expected that the magnetic moments of the silver atoms are randomly orientated, so they should be deflected by different amounts depending on their orientations. However, they found that half of the silver atoms were deflected upwards and half of them were deflected downwards by the same amount (two discrete points of accumulation in the machine). These two states are known as ‘spin up’ and ‘spin down’, showing the quantised nature of the spin. If you look at the silver atom, there are in total 47 electrons. In 46 of these electrons, each spin-up is paired with one spin down. The spins neutralise each other, so what is left is one unpaired electron - the 5s electron. This electron can be either spin up, spin down or any superposition of these two states - which means that its spin can point in any direction. As all the silver atoms have spins pointing in different directions, they are effectively unpolarised. The inhomogeneous magnetic field, therefore, acts as a filter and forces the spin of a silver atom to take a random orientation in either the same or the opposite direction of the magnetic field. If the spin state of a silver atom is closer to up, it is very unlikely to change its direction to down [16].

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Dirac

Fig 5. Dirac’s equation Source: BBC (©StellarioCama) Dirac’s equation (See Fig. 5) was derived in 1928 and it combined quantum mechanics with Einstein’s theory of relativity (the behaviour of fast-moving bodies) [4]. His equation was revolutionary because it revealed the existence of the antiworld the equation works not only for an electron but also for a positron (the antiparticle of the electron) [12]. Quantum mechanics deals with the motion of tiny particles; their small size brings about uncertainty in the accuracy of their position in time and space. In 1926, Erwin Schrodinger derived the equation of quantum mechanics for slow-moving particles (‘slow-moving’ relative to the speed of light) known as The Schrodinger’s Equation. It explained how electrons behave in atoms, and that an electron in a hydrogen atom is moving with a speed of about two thousand kilometres per second. It also explained why the orbital motion of electrons in atoms caused spectral lines to multiply in magnetic fields (but doesn’t explain electrons’ ‘spin’) [4]. Oscar Klein tried to generalise Schrodinger’s theory by using E 2 and Einstein’s hypotenuse relation. The square root of 25 can be either +5 or -5 (positive or negative). Since you can’t have negative length, the negative answer was rejected (taken as false); however, it left people feeling unsure. Dirac wanted to write an expression for the energy of an electron using E instead of E 2 (using a way other

than square rooting the whole Einstein Hypotenuse equation). He aimed to find an equation showing how a sum of some amount of mc 2 and pc would give E (in this case, the energy of an electron) [4]. Imagine a right-angled triangle with the side lengths of 3, 4 and 5 (5 being the length of the hypotenuse), and as I have mentioned above, we are taking some amount of ‘3’ and ‘4’ and they should add up to 5. This can be written as 4a + 3b = 5 Then, square the equation to get 16a 2 + 12ab + 12ba + 9b 2 = 25 This equation should be the same as the hypotenuse form, where 16 + 9 = 25, which means that a 2 = 1, b 2 = 1, and ab + ab = 0. However, there are no numbers when squared would give 1 but whose product ab would be zero [4]. This is not only for 3, 4 and 5; but for any combination. Effectively, we are trying to match the two equations E 2 = b 2 (mc 2) 2 + a 2(pc) 2 + a × b[(pc) × (mc 2)] + b × a[(mc 2) × (pc)] and E = (mc 2) 2 + (pc) 2 2

This cannot be solved using numbers but it can with matrices. The two matrices that can solve Dirac’s problem are

a 2 and b 2 each equal to 1 and if you multiply ab and ba, you get and

So ab + ba = 0, which solves Dirac’s problem [4].

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Antimatter and CP symmetry Antimatter, as the name suggests, is the opposite of matter. For instance, in the anti-world, positrons (anti-version of the electron) and antiprotons (anti-version of the proton) would exist. However, if these particles and their respective antiparticles are the same but different at the same time, what does that mean? It means that the anti-version of a particle (made of matter) would have the opposite charge and would be mirrored, in other words, it would show parity. This is known as CP Symmetry - C for Charge and P for Parity [4]. The thing that stays the same between the particle and its antiversion is its mass. To help with the understanding of CP Symmetry, I have included a diagram (See Fig. 6) that illustrates this.

F i g. 6 ‘ D a y a n d N i g h t ’ - A p a i n t i n g m a d e by Maurits Cornelis Escher in 1938. The painting is mirrored (parity) and its charge is swapped over (represented by the colour change between black and white). As you can see, after changing its ‘charge’ and p a r i t y, t h e p a i n t i n g a f t e r w a r d s ( o n t h e right bottom corner) is identical to the original one (on the left top corner). S o u r c e : Ta l k b y Ta r a S h e a r s - A n t i m a t t e r : Why the anti-world matters (The Royal Institution) [3]

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Mirror symmetry and parity A right-handed coordinate system is useful in finding out what a mirror image shows. The coordinate system shows the x-axis (represented by your index finger), the y-axis (represented by your middle finger) and the z-axis (represented by the thumb) (See Fig. 7) [7].

F i g. 7 T h e R i g h t H a n d C o o r d i n a t e S y s t e m and the Left Hand Coordinate System (which are mirror images of each other). Fo r t h e r i g h t - h a n d c o o r d i n a t e s y s t e m , t h e direction at which the thumb is pointing at is along the z-axis, the index finger is pointing in the direction along the x-axis and the middle finger is pointing the direction along the y-axis (for the lefthand coordinate system, it is along the -y-axis). Source: Scratchapixel If you place your right hand next to the mirror, then the mirror image should show the x-axis and the z-axis going in the same direction as that of your right hand; however, the y-axis becomes -y. Hence, the mirror image is a lefthanded coordinate system (See Fig. 7) [7]. This demonstrates how mirror reflections show a change in handedness. Imagine a screw. If you turn it clockwise next to a mirror, the mirror image should show the screw turning anticlockwise. In mechanics terminology, the screw we are turning clockwise is a right-handed screw and the mirror image shows a left-handed screw. In Mirror Symmetry (also known as parity conservation), there should be no change in handedness; therefore, the laws of nature should show no preference for right-handedness or left-handedness [7].

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Parity can be described as a transformation - a mirror reflection and a rotation of 180° about the new y-axis [7]. (x, y, z) (x, -y, -z)

(x, -y, -z) (-x, -y, -z)

This transformation can be seen with electromagnetism. If you place a solenoid next to a mirror, then using the right hand grip rule, your thumb should show the direction of the magnetic field when you fingers are curled up in the direction of conventional current. If you apply the same rule for the mirror image of the solenoid, you will find that the direction of the magnetic field will be opposite to that of the solenoid itself [7].

F i g. 8 A p o s i t i ve l y c h a r g e d particle in a magnetic field, and its mirror image. Image Reproduced from Figure 3 of Daniel, Michael. “The Ozma P r o b l e m . ” P h y s i c s R e v i e w, M a y 1998, p.21 [7]

If you look at a positively charged particle moving in a magnetic field at a certain direction (as seen in Fig.8), then using Fleming’s Left-Hand rule, we can determine the direction of the force on the charged particle. The mirror image would have the positively charged particle moving in the same direction (parallel to that of the original one) but its magnetic field and force would be going in the opposite directions. You can see the parity transformation of the mirror image from the original. What is more astonishing is that this parity transformation obeys the laws of electromagnetism - like charges repel [7]!

PHYSICS AND TECHNOLOGY

The Ozma Problem

The Ozma Problem poses a scientist on Earth who communicate with aliens, them which direction left

the scenario where you are just received a mission to and your first task is to tell is. How can we do this?

PHYSICS AND TECHNOLOGY This is a challenging task because everything that is controlled by gravity and the strong nuclear force shows mirror symmetry. Which means that up and down, left-hand side and right-hand side, are all relative to one another [6]. For example, if you set up two cameras in a laboratory and record a video of an experiment taking place, then take this original video of the experiment and mirror it, and subsequently send both videos (nonmirrored and mirrored) to another laboratory, the scientists at the other laboratory wouldn’t be able to distinguish between the two - whether one of the videos was real or the mirrored version. This reinforces the fact that the laws of nature are ‘mirror symmetric’ [7]. If there are no shared reference objects between us and the aliens that can help us solve this problem, then how are we supposed to tell them what left is? Most would think that up to this point, this task is virtually impossible. However, In 1956, the Chinese-American physicist Chien Shiung Wu conducted a nuclear physics experiment, and the aim was to see whether or not P-conservation (conservation of parity) also applies to weak nuclear force, just as it does with electromagnetism and strong nuclear force [8]. The results of the experiment have established that the conservation of parity was violated by the weak nuclear force, which meant that it would be possible to distinguish between a mirrored version of the world and the mirror image of the current world, as they would behave differently [8]. Wu’s experiment monitored the decay of Cobalt-60 atoms that were aligned by a uniform magnetic field (the weak interactions are responsible for decay) [8]. The alignment of the atoms is important as it minimises the random fluctuations that occur at higher temperatures. When the temperature gets closer to absolute zero, the cobalt nuclei can behave like tiny bar magnets, each of them having a north and south pole. This gives them their ‘spin’ which allows them to line up with the direction of the magnetic field lines [7]. Cobalt-60 is an unstable isotope so it will undergo decay to the stable isotope of Nickel-60. Electrons and gamma rays are emitted in this process as well [8].

F i g. 9 T h e B e t a Decay of Cobalt-60. Source: Wikipedia [8] The emission of gamma rays is essential in determining whether the weak nuclear force obeys or violates the conservation of parity. Gamma rays are photons and they go through an electromagnetic (EM) process when released from the Cobalt-60 nuclei. The emission of gamma rays is essential in determining whether the weak nuclear force obeys or violates the conservation of parity. Gamma rays are photons and they go through an electromagnetic (EM) process when released from the Cobalt-60 nuclei.

PHYSICS AND TECHNOLOGY Electromagnetic (EM) radiation obeys the conservation of parity, hence they would be emitted almost symmetrically in all directions (isotropically). Thus, the distribution of the gamma rays acts as a control for the distribution of the emitted electrons. The experiment used this principle, counting the rate of emission for gamma rays and electrons in two distinct directions and making comparisons. If the counting rates for the electrons were similar to those of the gamma rays, then parity would be conserved by the weak interaction. However, if the counting rates were very different, then the weak interaction violates the conservation of parity [8]. Asymmetry is shown as the electrons appear to be emitted predominantly in one direction than the other, which is in the direction opposite to the direction of the magnetic field [7], which in turn is opposite to the nuclear spin (See Fig. 10) [9] [10].

Since the direction of the magnetic field in the mirror-reversed arrangement is upwards, it should be in the same direction as the emission of electrons (predicted direction of beta emission if parity were conserved). This is contrary to observation because the experiment has shown that the emission of electrons (beta emission) is going downwards. The mirror-reversed arrangement is not realised in nature so mirror symmetry is violated. In turn, the conservation of parity is violated in the weak nuclear force [7]. So we can tell the aliens that they should do the same experiment as Wu did, and the end that emits the most electrons is the end that we call ‘south’. Then, label the ends of the magnetic axis of the field used for lining up the nuclei, and this in turn can be used for labelling the ends of a magnetic needle. Take a long piece of wire and arrange it to carry electric current away from you and place the magnetic needle above the wire. The north pole of the needle will point in the direction we call ‘left’ [11].

However, we encounter another obstacle. What if the aliens are made out of antimatter and they all live in an antiworld? Could there be a way of determining this? And how would we be able to explain what ‘left’ is to them now? [6]

Fig 10. The β decay of Cobalt-60 and its mirror image - notice how the original arrangement shows the rotational axes as left-handed a n d t h e m i r r o r - r e v e r s e d a r r a n g e m e n t s h o w s i t a s r i g h t - h a n d e d . Fo r your information, the direction of the magnetic field in the original arrangement is going downwards whereas in the mirror-reversed arrangement, the direction of the magnetic field is going upwards (See Mirror Symmetry And Parity). Source: Wikimedia Commons

PHYSICS AND TECHNOLOGY

In order to determine whether or not the aliens are made out of antimatter and live in an anti-world, we can look into the electrically neutral variety of K mesons. When they decay, a pion that is either positively or negatively charged is produced, which is accompanied by an electron or a positron respectively. Asymmetry can be seen in these decays because if matter and antimatter were perfectly opposite to one another, the chance of each decay occurring would be the same. However, in reality, they are a bit different [4]. The Neutral K and the anti-K each have 2 versions: short and long-lived. The long-lived versions (of both the original one and the anti-version one) show a bigger effect in the difference - hence it is used. Whether the K is mirrored or not, the decay of the long-lived K into a positron (along with a negatively charged pion) is always more likely to happen than the decay of the long-lived K into an electron (along with a positively charged pion). Out of 2000 decays, approximately 1003 of them will result in a positron (with negatively charged pion) and 997 of them will result in an electron (with a positively charged pion) [4]. Notify the aliens so that they can identify K, and since we can’t use the name since aliens would call it something else, tell them that it is the thing that weighs slightly more than half the mass of a proton or antiproton. Since they would also call the proton something else, tell them what we mean by the proton - the massive particle in the ‘nucleus’ at the centre of the alien’s simplest atom. Once the aliens have identified K, tell them that we are talking about the electrically neutral one (since there is K+ and K-). We need to tell them that the property that holds the atom together is what we call ‘charge’ and that we are talking about the K with no charge. The alien now knows that we are talking about the long-lived K0 [4]. Then, ask the alien:

‘Is the lightweight particle that is produced most often in the decays of the long-lived K0 (or anti-K0) the same as you find in your atoms, or is it the opposite?’.

I f the alien answers that it is the same, then there are positrons orbiting the

atoms in the alien world, which means that the alien is made of antimatter.

I f the alien answers that it is the opposite, then the alien is made of matter because electrons are orbiting their atoms, just like what we find in our world.

the aliens are made of antimatter, we can tell them what ‘left’ is by saying that the thing that they decay into less frequently (the electron) is made of matter and is moving in a ‘left-handed’ way [6].

I f the aliens are made of matter, then they can conduct the method I have mentioned above that applies the Wu Experiment [4].

PHYSICS AND TECHNOLOGY

Science fiction or reality For several decades, people have been fascinated by antimatter and its annihilation when it meets with matter where both matter and antimatter are destroyed (a self-destruction). This meeting is almost instantaneous and releases a large amount of energy. An annihilation of just one kilogram of antimatter will release about ten billion times the amount of energy given out when a kilogram of TNT explodes [4]. Hence, there is no question as to why people ponder about whether antimatter weapons should be the ‘next big thing’; however, in reality, it is not feasible to make these weapons.

This is because even before making a kilogram of antimatter, making a single gram of it (which would equate with the Hiroshima bomb with a yield of 20 kilotons of TNT) would take a long time. For example, in order to make a gram of antiprotons, you will need 6 × 10 23 (Avogadro’s constant) of them. The quickest source is at the Fermilab, USA. In the month of June 2007, they produced 10 14 antiprotons. If they were able to do this for a year, they could get approximately 10 15 , which is equivalent to 1.5 billionths of a gram. Annihilating this amount of antimatter releases 270 Joules only, which is the same amount of energy required to illuminate a single electric light bulb for five seconds [4]. This shows how inefficient the process of making these antiparticles is. We can only make a few of them over a long period of time, and due to the law of the conservation of energy (some energy is wasted in the process of making the antiparticles), the energy released from

the annihilation would be less than the total energy we would have to put into the whole project! Another reason why making weapons of antimatter is unrealistic is the way in which we have to store them. This means that we have to ensure that the antimatter doesn’t get in contact with matter. You would need a high vacuum and a container with strong electric and magnetic fields. This is possible as scientists have successfully stored antiparticles in Penning traps for many weeks, but there is a limit to how many you can keep in one bottle. When lots of charged particles are in a small volume, they will repel one another. Hence, it becomes more difficult to keep them inside the magnetic bottle. Approximately a million antiprotons is the largest number successfully stored however that is actually many billions of times smaller than the number of antiprotons required for a gram [4].

PHYSICS AND TECHNOLOGY

Fig 11. An artist’s rendition of an antimatter propulsion system Source: Wikimedia Commons

One suggestion is storing antiprotons and positrons together. As antiprotons are negatively charged and positrons are positively charged, this takes away the problem of electric repulsion. However, this poses another problem due to the fact that if the antiprotons and positrons paired up, the overall net charge would be 0 (neutral). Which means that the electric and magnetic fields cannot keep the antiparticles inside anymore as they can only affect charged particles, so they will move out and annihilate. There are also other potential ways in storing antiparticles like antihydrogen atoms; however, these ways also place a limit to how many can be stored per bottle [4]. Regardless of these limitations, research into fuelling spacecrafts with antimatter continues. In the Cassini-

Huygens probe to Saturn, more than half of its weight was in its fuel and oxidiser tanks, and the launch vehicle weighed more than 180 times the probe itself. If antimatter fuel could be used, then a mass equivalent to a grain of rice could power a spaceship to Mars instead of using three tonnes of chemical propellant. Antimatter fuel for space travel at the moment is still not possible because in order to store even one millionth of the amount needed for the Mars trip, a lot of electric force is needed to push on the walls of the fuel tank (due to the electrical repulsion between the antiparticles of the fuel). This means that the equipment in producing this strong electric and magnetic field in the antimatter fuel tank would weigh a lot, which counteracts the primary advantage of antimatter fuel [4].

In the media, Science Fiction has made false statements about antimatter weapons. In Dan Brown’s Angels and Demons, it mentions how antimatter annihilation results in ‘No byproducts. No radiation. No pollution.’, which is false since a large amount of energy is released in the form of gamma rays [4].

PHYSICS AND TECHNOLOGY

Conclusion If you have read up to this point, I hope that this article has offered you a good insight into concepts ranging from the existence of antimatter to the realms of the universe. Indeed, the world of quantum physics is a complicated one, and there is so much more about it that I didn’t include in this article. During my research, I was utterly astounded by how physicists could derive equations that link space, energy and momentum together in such an impeccable way. I am confident that more discoveries in quantum physics will soon come to fruition, and they will help us understand things that we have yet to find out. There is just so much out there that we still do not know.

‘Those who are not shocked when they first come across quantum theory cannot possibly have u n d e r s t o o d i t .’ - Neil Bohr

PHYSICS AND TECHNOLOGY BIBLIOGRAPHY [1] Sharp, Tim. “What Is an Atom?” LiveScience, Purch, 11 S e p t . 2 0 1 9 , w w w. l i v e s c i e n c e . com/37206-atom-definition.html. [2] “Origins: CERN: Ideas: The Building Blocks Of M a t t e r. ” E x p l o r a t o r i u m , w w w. e x p l o r a t o r i u m . e d u / origins/cern/ideas/standard. html#:~:text=Scientists%20 once%20thought%20the%20 most,particles%20called%20 protons%20and%20neutrons. [ 3 ] “ Ta r a S h e a r s - A n t i m a t t e r : W hy t h e A n t i - Wo r l d M a t t e r s . ” Pe r f o r m a n c e b y Ta r a S h e a r s , Yo u Tu b e , T h e R o y a l I n s t i t u t i o n , 1 8 O c t . 2 0 1 3 , w w w. y o u t u b e . c o m / w at ch ? v = 0 F y 6 o i I Rw J c [ 4 ] C l o s e , Fr a n k E . A n t i m a t t e r. Oxford University Press, 2018. [5] The Editors of Encyclopaedia Britannica. “Speed of Light.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 17 M a y 2 0 1 9 , w w w. b r i t a n n i c a . c o m / science/speed-of-light. [ 6 ] R e i c h , H e n r y, d i r e c t o r. H o w t o Te l l M a t t e r Fr o m A n t i m a t t e r | CP Violation & The Ozma P r o b l e m . Yo u Tu b e , M i n u t e p h y s i c s , 2 6 F e b . 2 0 2 0 , w w w. y o u t u b e . c o m / watch?v=Elt0Gt9Cb6Q [7] Daniel, Michael. “The Ozma P r o b l e m . ” P h y s i c s R e v i e w, M a y 1998, pp. 19–22. [ 8 ] “ Wu E x p e r i m e n t . ” Wi k i p e d i a , W i k i m e d i a Fo u n d a t i o n , 2 9 Ju n e 2 0 2 0 , e n . w i k i p e d i a . o r g / w i k i / Wu _ experiment. [ 9 ] “ M a d a m e Wu a n d the Backward Universe.” G a l i l e o ’ s P e n d u l u m , 8 M a r. 2014, galileospendulum. org/2014/03/08/madame-wu-andthe-backward-universe/. [ 1 0 ] N a v e , C a r l R o d . P a r i t y, h y p e r p h y s i c s . p h y - a s t r. g s u . e d u / h b a s e / q u a n t u m / p a r i t y. h t m l . [ 1 1 ] G a r d n e r, M a r t i n . T h e N e w Ambidextrous Universe: Symmetry and Asymmetry from Mirror Reflections to Superstrings.

Dover Publications, 2005. [ 1 2 ] H i g h f i e l d , R o g e r. “ H o w D i r a c P r e d i c t e d A n t i m a t t e r. ” New Scientist, 12 May 2009, w w w. n e w s c i e n t i s t . c o m / a r t i c l e / dn17111-how-dirac-predictedantimatter/. [13] Nave, Carl Rod. “Zeeman Effect in Hydrogen.” Zeeman E f f e c t , h y p e r p h y s i c s . p h y - a s t r. g s u . edu/hbase/quantum/zeeman.html. [14] The Editors of Encyclopaedia Britannica. “Zeeman Effect.” Encyclopædia Britannica, Encyclopædia B r i t a n n i c a , I n c . , 2 0 Ju n e 2 0 1 1 , w w w. b r i t a n n i c a . c o m / s c i e n c e / Zeeman-effect. [15] “What Exactly Is the ‘Spin’ of Subatomic Particles Such as Electrons and Protons? Does It Have Any Physical Significance, Analogous to the Spin of a Planet?” Scientific American, Scientific American, 21 Oct. 1 9 9 9 , w w w. s c i e n t i f i c a m e r i c a n . com/article/what-exactly-is-thespin/. [16] The institute for physics education research, Münster u n i v e r s i t y, c r e a t o r. S t e r n Gerlach Experiment (U2 07 03). Yo u Tu b e , S t e f a n H e u s l e r, 2 5 J u n e 2 0 1 9 , w w w. y o u t u b e . c o m / w a t c h ? v = P H 1 F b k LV J U 4 . [17] “Large Electron–Positron C o l l i d e r. ” W i k i p e d i a , W i k i m e d i a Fo u n d a t i o n , 8 Ju l y 2 0 2 0 , en.wikipedia.org/wiki/Large_ Electron%E2%80%93Positron_ C o l l i d e r. [ 1 8 ] “ L a r g e H a d r o n C o l l i d e r. ” W i k i p e d i a , W i k i m e d i a Fo u n d a t i o n , 3 Ju l y 2 0 2 0 , e n . w i k i p e d i a . o rg / w i k i / L a r g e _ H a d r o n _ C o l l i d e r. [19] “CERN Accelerating Science.” CERN, home.cer n/ science/physics/higgs-boson. [ 2 0 ] Wo l c h o v e r, N a t a l i e , a n d substantive Quanta Magazine moderates comments to facilitate an informed. “The Physics Still Hiding in the Higgs Boson.” Q u a n t a M a g a z i n e , 2 0 1 9 , w w w. quantamagazine.org/the-physicsstill-hiding-in-the-higgsboson-20190304/.

PHYSICS AND TECHNOLOGY

Material Sus How to provide th

plasti at the if a were

Illustration by Isabel Chau

PHYSICS AND TECHNOLOGY

stainability:

e same with less? Katrina Cheng

“ P l a s t i c a c c o u n t s f o r ab o u t 1 % o f t h e U K ’s c a r b o n d i ox i d e e m i s s i o n s, a n d p l a s t i c b a g s m a ke u p 1 % o f i c u s e. ” Ju l i a n M A l lwo o d , P r o f e s s o r o f E n g i n e e r i n g e U n i ve r s i t y o f C a m b r i d ge, o n c e s a i d . I n f a c t , “ eve n all plastic bags were scrapped and their substitutes c a r b o n n e u t r a l … we wo u l d o n ly b e a d d r e s s i n g 0 . 0 1 % o f t h e U K ’s c a r b o n f o o t p r i n t ” . To truly reduce carbon emissions and find the solution, we need to start focusing on scale and identif ying areas that can actually make a significant difference. Out of the total global carbon emission, 64% are energy-related, of which 35% a r e f r o m t h e i n d u s t r y, 31 % are from buildings, and 27% are from transport. Climate scientists tell us that we have to cut our gas emissions to zero by 2050 and that we are not even close to this goal. Environmental impacts of material production and processing are becoming increasingly impossible to ignore and one of our biggest opportunities for change comes from material efficiency e s s e nt i a l l y, providing the same with less.

Steel is 100% recyclable once it is produced as it has a theoretically endless life cycle. Here is the cycle simplified: iron ore is mined, melted then manufactured, the consumer orders the required steel for its required purpose (transport , buildings, appliances) and the steel enters its ‘use’ phase. Once the steel is exhausted, it is recycled through melting or used as steel scrap where the whole c y c l e r e p e a t s . To a d d r e s s material sustainability regarding the whole cycle, we can target the two areas with the most significant gain and which save as much as 75% of energy: material design and material reuse.

PHYSICS AND TECHNOLOGY

one. M AT E R I A L D E S I G N

â€œAt least 25% of liquid steel and 40% of liquid aluminium ne ver get made i n t o p r o d u c t s ,â€? A l l w o o d s t a t e s . F o r s i m p l i c i t y , m a t e r i a l s i n t h e i n d u s t r y a r e manufactured into regular shapes and sizes, which are then cut into smaller p i e c e s a c c o r d i n g t o t h e a p p l i a n c e n e e d e d . Un f o r t u na t e l y, b y d o i n g s o , there are metals in perfect condition that are left unused when cutting and p r o c e s s i n g. I n r e a l i t y, t h e m e t a l s c ra p f o r m e d i s m o r e o f a ha b i t ra t h e r t ha n a n e c e s s i t y. I f m a n u f a c t u r e r s s t a r t e d u s i n g a l l m e t a l s m a n u f a c t u r e d t o m a x i m u m e f f i c i e n c y, w e c o u l d c u t c a r b o n e m i s s i o n s b y 7 % i n t h e a l u m i n i u m i n d us t r y a n d a f u r t h e r 1 6 % i n t h e s t e e l i n d u s t r y. I n t h i s s e c t i o n o f t h e p a p e r, w e w i l l explore different ways of saving materials through different designs; we will also explore reasons why good-quality steel and aluminium remain unused a n d s t a r t i n t r o d u c i n g p o t e n t i a l s o l u t i o n s t o a c h i e v e m a x i m u m e f f i c i e n c y.

PHYSICS AND TECHNOLOGY

1. YIELD LOSSES

Imagine this scenario: you are making cookies for your a f t e r n o o n t e a p a r t y . Yo u r o l l out the cookie dough into a rectangular block and bring out your circular shaped c o o k i e c u t t e r . Yo u f i t a s m a n y circles onto the dough until there is no more extra space. Then you would usually take the leftover dough, roll it out, and repeat this process until you use up all the dough. With your freshly baked cookies and drinks prepared, your tea party begins. In the construction i n d us t r y, w e c a l l t h e p r o c e s s used by the cookie-cutter a s ‘ b l a n k i n g ’. S a d l y , i n t h e ma t e r i a l i n d us t r y, w e c a n n o t

very easily roll the leftover dough out again and repeat procedures. Instead, the leftover dough, known as m e t a l ‘ s c r a p ’, w i l l s i m p l y not be part of the final component and will need to be recycled under an energyintensive melting process, further contributing to the greenhouse gas effect. In a later section titled ‘ M a t e r i a l R e u s e ’, w e w i l l explore how such scrap in good condition and without surface corrosion can be trimmed and processed to be part of a new application - a process that sounds very ideal, yet is only done on a very small scale.

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Reasons for yield loss Despite very few customers actually wanting the shape they purchase, the reason that the steel and aluminium industry continues to manufacture fixed sizes is due to economic reasons and m a n u f a c t u r i n g s i m p l i c i t y. F o r i n s t a n c e , because aircraft wings are thinner at the tip than the centre, a perfectly uniformed plate will need to be wedged into the shape of the airfoil. Also, can makers, similar to cookie-making, want circular disks of aluminium sheets to ma k e t he c a ns . Howe v e r, t he y r e c e i v e perfectly rectangular sheets from which they blank circles and send the leftover scrap for remelting. Poor tessellation will cause us to scrap 26% of all liquid steel and 41% of all liquid aluminium; this is recycled and melted in an energy-intensive process, once again contributing to the total global carbon footprint. Imagine pieces of scrap that might never end up in any components or applications but are forever part of a permanent energy-demanding cycle! Liquids solidif y from the outer surface into the inner surface, and for liquid metals with complex compositions, the whole composition of the remaining

liquid changes. As a result, the head and tail of each aluminium cast are removed by scalping. After casting, most steel and aluminium are rolled out, which has a significant throughput in the middle of each coil or place, forcing the head and tail of any rolled material to be cut off. At the same time, the cracked edges formed during rolling are also trimmed. This will already contribute to around 25% of all yield losses in steel and a further 40% of all yield losses in aluminium. A d d i t i o na l l y, a l t h o u g h m o s t s h e e t s a r e supplied flat, their final product is not flat in use. This requires the common p r o c e s s o f â€˜ d e e p d r a w i n g â€™, w h i c h i s forming and moulding the flat sheet into shape. If a sheet is formed without gripping its edges, a cup, for instance, w i l l b e v e r y s h a l l o w a n d t e a r. S i m i l a r l y, if edges are not restrained, the edges will wrinkle. Deep drawing allows the gripping of the edges to prevent wrinkling and tearing. A ver y clever a nd e ff i c i e nt pr o c e s s at t hat ; howe v e r, it requires about 25mm to be trimmed from each finished part - leading to a further yield loss of about 15%.

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Potential solutions to reduce yield losses Designers of metal components are largely unaware of the implications of their geometric choices, but they could employ potential designs with tessellating or nearly tessellating shapes. Let â€™s take a look at the clothing and textiles i n d u s t r y. T h e y f a c e a s i m i l a r c h a l l e n g e f o r f a b r i c , and have now developed sophisticated computer algorithms to maximise clothing yield from rolls of fabric. In fact , many cut out the fabric with fast laser cutters to further optimise blanking patterns. Sp e a k i n g t e c h n i c a l l y, i f w e ha d a l a r g e v a r i e t y of shapes, the chance of finding small pieces to f i t i n b e t we e n la rg e r o ne s is hi g he r, i nc r e as i ng t h e y i e l d . Ye t a t p r e s e n t , t h e b l a n k i n g p r o c e s s e s used in cutting parts from metal are designed to cut one piece from the coil then move forward to cut the same shape again along the coil, giving very little opportunity for tessellation. Similar t o t h e t e x t i l e i n d us t r y, l a s e r c u t t i n g f o r m e t a l is o c curr i ng ; howe v e r, t he pr o c e s s is r e lat i v e l y s l o w, ma k i n g i t v e r y d i ff i c u l t t o c o m p l e t e l y translate fabric cutting into metal sheets.

PHYSICS AND TECHNOLOGY Many exciting manufacturing technologies are under development , and the whole field of 3D printing has attracted a lot of attention. The 3D printing machine can essentially make shapes and objects programmed into it. For example, the aerospace industry is looking at making c o m p l e x p a r t s o f t i t a n i u m u s i n g t h i s n e w t e c h n o l o g y. 3D printing follows a process known as ‘selective laser melting’ where the powder of the material is placed under a scanning laser that then draws the pattern of the p r o d u c t , m e l t i n g a n d b o n d i n g t h e p o w d e r. T h i s p r o c e s s repeats until all layers are formed. 3D printing has its drawbacks, however : only powdered metals are usable, which is formed by energy-intensive processes of spraying and freezing, lasers are energy-demanding, printing rate is s l o w a n d s u r f a c e s a n d s m a l l c o r n e r s c a n b e o f b a d q u a l i t y.

Over-specification The cost of steel is lower compared to the cost of labour in developed countries, so it is generally cheaper to save the cost of labour than to save materials. During construction, designers do not ever want a lack of materials to be a concern or a problem since when everything is in excess, the risk of a m a t e r i a l p r o b l e m i s l o w e r. I n g e n e r a l , t h e m a i n d r i v e r o f o v e r specification is conser vatism. Designers often over-specif y the amount of steel in a building by 30-40% even though they rarely have been required to use this surplus; they are concerned that clients will change the specification of their buildings at a late stage, so they factor and build in extra capacity ‘just in case’ any plans change. In a case where clients ask for lightweight, efficient buildings, designers know exactly what to do and can lead to a saving of 50% of the material used. This suggests that over-specif ying is not a technical challenge and may even reduce the overall cost , but will only occur through conscientious clients requesting it. After the analysis of 23 buildings in London, a report found that on average only 50% of the steel in their beams was utilised in meeting the standards, suggesting that if we met Eurocode requirements rather than exceeding it , we can cut emissions from commercial buildings by 80%.

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Illustration by Tina Wu

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2. ADAPTED DESIGNS Structural optimisation is a discipline dealing with the optimal design of load-carrying mechanical structures to minimise the total weight of the structure subject. Apart from aerospace applications where every extra mass makes a big difference, optimisation is rare and is usually only limited to small moving parts.

Beams Figure 1 shows a simple point load supported by an arm some distance from a wall. It can represent a crane or a b a l c o n y . To m a k e s u r e t h e a r m w o n ’ t break , we need to ensure it is strong enough by designing for stiffness rather than strength. The arm from Figure 1 has a uniform load spread, so it is most likely to break at the wall. For a stronger arm that won’ t break at the wall, we want it deeper near the wall and shallower near the tip. This brings us to Figure 2, a more optimised design in which the depth of the arm varies, giving the arm a high stiffness a t t h e t i p . A l r e a d y, F i g u r e 2 i s l i g ht e r than Figure 1 by 16% and has reduced me t a l us e . Howe v e r, b o t h t he f i r s t and second beam would fail when a load is applied. The Figure 2 beam’s failure will start at the upper and lower s u r f a c e s . L o g i c a l l y, i t ma k e s s e n s e t o have more material on the upper and

lower surfaces and make the middle t h i n n e r. T h i s t h e o r y b r i n g s u s t o F i g u r e 3, in which the cross-section of the b e a m l o o k s l i k e a c a p i t a l “ I ”. T h i s i s t h e standard form in which structural steel is used. I-beams are made by rolling with specially shaped rollers with the same cross-section along their length due to manufacturing convenience. If we compare Figure 1’s design with a standard I-beam with constant crosssection, 54% of the mass is saved; if we then compare Figure 1’s design with Figure 3’s variable I-beam, there is another 85% reduction in mass. As loading increases, the required deflection must decrease, and to do so, the cross-sectional area must i n c r e a s e . We s h o u l d a i m t o r e d u c e the required loads and increase allowed deflections - an application a l r e a d y b e i n g u s e d i n t h e i n d u s t r y.

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1. 2. 3.

Standard universal I-beams are the key components of steel-framed buildings. They are designed for bending stiffness and used as horizontal beams to support floors and roofs; they are manufactured in a standardised set of geometries and listed by steel producers. Within the list, their geometry is constant; a constant cross-section is chosen for ease of manufacture, so it is not p e r f e c t l y e ff i c i e nt . Howe v e r, o nc e a ga i n, clients will often over-specif y â€˜just i n c a s e â€™, w h i c h m a y b e q u i t e w a s t e f u l knowing that the office is already strong enough to hold a swimming pool on e a c h f l o o r. O v e r - s p e c i f i c a t i o n o c c u r s i n construction because of a process called rationalisation. A young civil engineer would choose to design a building according to standard codes and choose t he o pt i mum b e a ms ; howe v e r, whe n a n older and more experienced engineer reviews the design, he or she will reduce the number of different beam sections required. This decision simplifies the job for building contractors because of the lower cost of steel compared to the cost of labour in developed countries.

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Steel reinforcing concrete In an exploration of beams in construction, there are obvious and significant opportunities to reduce metal use, but they are not currently taken because of the higher relative c o s t s o f l a b o u r. T h e e x a m p l e u s e d here would be steel-reinforcing bars, commonly known as rebars. They are extensively used to provide structural reinforcement for concrete. Concrete is made of ceramic and other aggregates, making them strong in compression but weak in tension. On the other hand, steel rebars have properties opposite to those of concrete strong in tension, but weak in compression - and, thus, are added to provide tensile strength to concrete. Since rebar designs are often constrained by strength rather than stiffness, the selection of a stronger steel type to make the rebar would mean less material is needed to provide the same tensile strength. So if stronger steel Photo by Isabel Chau were selected to make the r e b a r, mass required could already be reused. There is a degree of rationalisation in the selection and in the layout of reinforcing steel since bars of the same diameter and same spacing are used across large areas to simplif y detailing, identification, laying and checking. This adds 15-30% more reinforcing steel than is strictly required to meet codes. Mo r e o v e r, t he r e is a d i ff e r e nt is su e with the over-specification of loads w i t h r e b a r s . Un f o r t u na t e l y, e v e n i f t h e building as a whole is designed without over-specification, designers and contractors would still make choices

m a k i n g e x c e s s r e b a r. T h i s i s b e c a u s e the simplicity and speed in laying out rebar in simple geometries at a single spacing and with as little different bar diameters as possible reduce the risk of m i s t a k e s a n d m a k e i n s p e c t i o n s e a s i e r. On a more positive note, modern computer control systems such as Qube can design meshes with var ying lengths, spacing and diameters. They minimise over-specification with an advanced finite element approach for designing and detailing r e i n f o r c e m e n t using the Bamtec prefabricated rolled reinforcement carpet system. These carpets typically comprise of smaller diameter bars which are placed at a reduced spacing to achieve the same reinforcement area required by design. These rolled carpets are robotically m a n u f a c t u r e d and read from detailed drawings. These complex bar sequences significantly reduce the degree of rationalisation without any loss of stiffness. Each bar is spot welded to thin gauge steel straps during manufacture and can quickly and easily roll out when transported to the construction site. Although it is not necessarily what is happening in practice, Qubeâ€™s approach is an attractive example of intelligent innovations that can lead to material savings. It is estimated that if size and placement optimisation is carried out to its maximum, we could reduce 15% of global rebar production.

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To p o l o g y To p o l o g y o p t i m i s a t i o n t a k e s a 3 D d e s i g n and literally removes material from it to achieve the most efficient design. There is no concern about aesthetics, traditional approaches, and any other u s u a l d e s i g n c o n s t r a i n t s . We s t a r t w i t h a very regular finite element analysis, FEM, of mesh occupying design space where the initial analysis will show the stress distribution and efficiency throughout this design space. The optimiser will remove the elements not under so much stress and with little s t r a i n e n e r g y. A s t h e a r e a s a r e r e m o v e d , the overall structure is analysed and checked to observe any changes. The topology optimisation of structures has proven to be a valuable tool for the identification of best concepts in the early phases of the design process. To p o l o g y optimisation wonderfully embodies the definition of material sustainability and is entirely adapted i n t o m o d e r n t e c h n o l o g y. I t i s w i d e l y u s e d in the lightweight design of structures in the automotive and aerospace i n d us t r y, a s w e l l a s c i v i l , ma t e r i a l , and bio-engineering with the aim of further expansion into other industries. In the beginning, the design variables are selected, and limitations of these variables and system performance factors such as stress and buckling are defined. By changing variable values, we can test to see how different changes can give the best combination among the design space. Design variables, size, and properties of materials are s e l e c t e d t o b e o p t i m a l . To p o l o g y optimisation helps to achieve efficient designs within a small time interval. With the help of FEM software, we can check designs for range, different loads and conditions and design and manufacturing constraints. Nowadays, we can use drawing software in forming different topologies and alter old designs to produce new alternative ones in virtual environments.

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Conclusion By using less metal in designs for all steel and aluminium, we could potentially use 30% less metal than we do at present, with no change in the level of material service provided, simply by optimising product designs and controlling loads they experience. In fact, it can lead to a 30% reduction in all emissions associated with steel and aluminium production. The consequence of this saving would actually lead to a greater reduction in emissions than estimated due to three co-benefits demonstrated with moving articles:

In any moving application, lighter vehicles use less fuel. If we stopped compensating for weight saving by introducing new luxury features, we would have reduced emissions even more than our estimate.

Lighter weight products have improved performance. Lighter cars accelerate, brake and turn better and lighter shipping containers can be lifted more r a p i d l y.

One lighter component leads to another lighter component. The weight of the structure of oil rigs below its surface depends on the weight of the topsides, and the decreased weight of t r a i n s l e a d t o r e d u c e d r a i l w e a r.

In general, there are different motivations for and against metal conservation in different industries. It is not only the size that benefits or the weight saving that motivates change but also other factors of costs and the preferences of customers.

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two. M AT E R I A L R E U S E

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1 . M A N U FA C T U R I N G S C R A P Cu r r e nt l y, 35% o f t h e w o r l d â€™s s t e e l is made from scrap, and the rest is from newly mined ore. Metal scrap is essentially the leftover product of manufacturing and consumption, such as parts of vehicles, building supplies and surplus materials, which are then put to use and returned to the cycle again. Using metal scrap can save e n e r g y. Ma k i n g l i q u i d s t e e l f r o m s t e e l scrap requires one-third of the energy needed to make the same steel from ore, emitting less than one-quarter of t he c a r b o n d i ox i d e e mis s i o ns . Howe v e r, scrap recycling involves melting with a temperature of around 1500 degrees Celsius, adding to the energy required. Overall, steel-making accounts for 9% of global carbon dioxide emissions, of which 1% is directly from steel scrap melting. Now looking at aluminium, one-third of the worldâ€™s aluminium is made from scrap. Since producing liquid aluminium from scrap needs around 20 times less energy than from ore, recycling aluminium is much more attractive and in demand. Recycling both steel and aluminium may seem like a very energy-efficient process compared to the energy needed from making new metal from ore, thus increasing recycling rates in the metal i n d u s t r y. H o w e v e r, c o n s i d e r i n g t h a t global metal demand will almost double over the next 40 years, the total energy required and the carbon footprint from scrap recycling will be very significant. Is there an alternative? Albeit on a small scale, metal reuse without melting is already possible. By making the right design choices, looking into emerging technologies, and adopting more collaboration between different sectors, limitations of metal reuse can be surpassed and metal reuse can be deployed on a large scale.

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Right design choices Without standardisation, disassembly is expensive, unless products are designed with disassembly in mind. For instance, to reuse components, we want to find components that can easily separate from parent products, without an overall effect on others, with just superficial change or simple t r i mmi n g. Mo r e o v e r, s t r u c tu r e s a r e b u i l t upon the premise of certified elements and well-executed fabrication and erection, along with marked standard specifications. Engineers, without the pressure of time, look favourably upon reusing steel and will most definitely enjoy an interesting challenge. Most of them would have no problem using r e us e d s t e e l ; howe v e r, t he s t e e l wo ul d have to be certified with the required properties and pass a controlled supply chain process. This will not only reassure the engineers but also gain a client â€™s confidence. Hence, reuse of construction materials would only be adopted by engineers and clients if the material properties are known. A way of doing so is at regular inter vals; we can mark and regulate different steel sections with information to determine steel size, grade and q u a l i t y, r e m o v i n g t h e n e e d t o t e s t a n d certif y the steel at the end of its life. The 1990s saw a shift from manual labour to mechanised demolition methods, further driven by governmental pressure to reduce health and safety

risks and by commercial pressure for time-saving. Demolition machines badly deform steel, which is not a problem for metals that are recycled through melting, but it is a major b a r r i e r t o r e u s e w i t h o u t m e l t i n g . Ye t site owners have a strong preference towards demolition in deconstruction due to its speed and ease. The consequence of this preference is that even when a building can be deconstructed, contractors will still opt for deconstruction, giving their reason as t i me . Howe v e r, whe n we l o o k at t he timeline, many derelict buildings are left for quite some time after planning decisions are made and before any action starts. By changing the sequence of decisions and effectively using this time for deconstruction instead of demolition, deconstruction can easily become the next norm. Mo r e o v e r, whe t he r i t is d e mo l i t i o n or deconstruction, contractors rarely own large stockyards that can hold large amounts of secondary steel, so they need to find a buyer or storage site before they start their job for the materials to be claimed immediately afterwards. Nonetheless, the economic va l u e o f s c ra p i s f a i r l y l o w, c r e at i n g a low-profit margin and discouraging any incentive to find ways to reclaim steel for reuse - a cycle that will repeat itself if we donâ€™ t add other factors.

PHYSICS AND TECHNOLOGY Un f o r t u na t e l y, o u r w o r l d ha s o t h e r i n c e nt i v e s n o t t o b e e c o - f r i e n d l y. M o s t m a n u f a c t u r e r s d o n o t see scrap as part of their core business resulting in production lines designed without considering the value of scrap. Larger blanking skeletons are chopped into small pieces for ease of handling and to prevent disruption to overall construction, instead of considering factors such as where to cut to minimise scrap produced. For instance, the aerospace industry places a high priority on the weight of materials, meaning 90% of highquality aluminium is turned into chips. They will sell swarf with alloys mixed for a price of around 1% of what t he y pa i d f o r, y e t s wa r f c a n be up to 90% of their output. Looking on the bright side, Abbey Steel, a family run business, buys steel obtained from a diverse range of UK manufacturing industries and resells the processed sustainable steel back into the i n d u s t r y. Industries consume large amounts of steel, leading to the production of waste material, a byproduct of this process. These waste materials cannot be used in any of the processes and are destined to be recycled through smelting. Abbey Steel steps in and reclaims the steel to be trimmed and put back into the supply chain - “reused n o t r e c y c l e d ”. B y d o i n g s o , the only energy required is for transportation and reprocessing of the steel, already reducing carbon dioxide emissions to 2.3 tonnes of CO2 per tonne of metal. Abbey Steel - the world’s first green brand of sustainably sourced steel - has been created to showcase a prime steel byproduct sourced from multi-industr y applications. This environmentally-friendly inspiration would be able to grow its business further if people were more willing to segregate more cut-outs for sale, especially to have car manufacturers hand over scrap.

PHYSICS AND TECHNOLOGY Photo by Isabel Chau

Emerging innovative technologies New creations such as solid bonding can bond aluminium chips into solid material without any melting, potentially replacing recycling by melting. Solid bonding is welding without addition of a brazing filler at a temperature below a metalâ€™s melting p o i n t . To b e g i n w i t h , c l e a n c h i p s o f a single alloy are compressed under high pressure and at a temperature of 450-500 degrees celsius. The high pressure and extension cause surface oxide layers to crack , revealing reactive aluminium metal which can be welded into a solid product. The oxide remains on the interface, but as an applied strain stretches the material, clean metal becomes exposed. Entrapped air oxidises some of the exposed metal and, provided the strains are great enough, clean metal will be extruded through cracks in the oxide. Solid bonded chips require 100

times less energy than the manufacture of primary aluminium, reducing carbon dioxide emissions by 96%. Although the solid bonded material shows a reduction of around 10% in ultimate tensile strength and 15% in d u c t i l i t y, f u r t h e r d e v e l o p m e nt c a n potentially reduce these differences. Overall, the surface quality and bonding of the bar pieces were ver y good. At the same time, many applications, including aluminium window frames, do not actually demand the full strength and full ductility of aluminium, meaning sustainable solid bonded material can be used here instead. If more trials succeed, the technology of solid bonding could soon be seen in the market - reusing 100kt of aluminium scrap would avoid up to 750kt of carbon dioxide emissions.

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Adopting collaboration between different sectors The lack of trust between sectors about the quality of steel can be a central problem and deter them from s t e e l r e u s e . Ve r y f e w w i l l c o n s i d e r reused steel if it costs more or takes mo r e t i me . Howe v e r, s o me d e lay s c a n be tolerated if the costs are lowered, or on the other hand, one may decide to pay more to speed up the program. Aft e r s u r v e y i n g ma n y, t h e r e i s a common perception that reusing steel is difficult , and there is an overall scepticism over steel reuse across the supply chain. The considerable difference between the perception of barriers and the experienced barriers indicates the lack of communication a c r o s s t h e s u p p l y c h a i n . To l i s t , fabricators are prevented from steel reuse due to the lack of the certification of the steel and the fact that the practice is uncommon; stockists have business models that will not allow long-term steel storage and there is no large cheap storage land, making it not economically viable. Demolition contractors also face the lack of a reliable market for reused steel, and structural engineers are pressed for t i m e . On t h e c o nt ra r y, a r c h i t e c t s , ma i n contractors and structural engineers are protected by this costly structure as they would simply charge higher costs to clients. Nonetheless, green projects do happen if there is a motivation to preserve a valued heritage or if reused elements serve a decorative purpose. Successful steel reuse projects are the result of a willing client and a tightly integrated team that perhaps is responsible for both design and rebuilding. For example, when the owner of the new building also owned the previous building (or has a

strong relationship with the previous owner) or when the main contractor is t he d e s i g ne r, a ny l e ga l unc e r t a i nt y is eliminated. When there is an opportunity for reuse, there are few obstacles to forming a practical plan. Still, there are limitations: structural design usually assumes elements will be fabricated as required, and this might not be the case with reused elements as desired sizes or lengths may not be available, and there would need to be substantial changes to pla n. Mo r e o v e r, t he r e is a n o l d a nd new perception to reused steel where clients feel that reused steel is inferior and thus refuse to accept reused steel. People can be ver y stubborn at times and refuse to accept new practices once again where development of trust and communication is needed. Let us be reminded that if just one sector in the supply chain is unwilling to adopt reused steel, the project cannot and will not go ahead. Building trust can take time, and if the different sectors hav e no t wo r k e d t o g e t he r, t he y w i l l rely on common practice and industry norms, meaning steel reuse becomes u n l i k e l y . To o v e r c o m e t h i s , f a b r i c a t o r s can be involved in projects from the start and will have more time to prepare for any uncommon operations. Indeed, as suggested by Allwood and Cullen, steel reuse can play an important part of a global strategy for the efficient use of materials as the carbon and energy embodied in structural frames can represent up to 20–30% of the as sumed 50-year lifetime carbon footprint of a building. “ Steel reuse can play an important part of a global strategy for the efficient use of materials as the carbon and energy embodied in structural frames can represent up to 20–30% of the as sumed 50-year li f e t i m e c a r b o n f o o t p r i n t o f a b u i l d i n g .” “Steel reuse is a potentially excellent strategy and general guidance about the reuse process is available. Nonetheless, widespread r e u s e d o e s n o t s e e m t o o c c u r .”

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2. LONGER LIFE PRODUCTS Most demand for products in developed economies isnâ€™ t to expand the overall stock but to replace existing items. For instance, we destroy 33% more fridges every year than we make cars. This suggests the need to modif y products and develop adaptable designs.

Reasons for replacing goods:

Degraded failure the product can no longer be used. For example when clothes are worn out or when metal surfaces are damaged.

Inferior failure - the user has changed, meaning the original product is no longer valuable to existing customers. For example, clothing no longer fits or a two-seater car cannot fit a n e w b o r n b a b y.

Unwanted failure the product still functions but is not valued by its current o wn e r. F o r e x a m p l e , t h e latest fashion or styling has changed or new legislations are introduced.

For degraded components, we can intervene through design changes, possible restoration to original speciation, or condition monitoring and maintenance for better prediction of when a component needs replacement or restoration. In fact , all of these practices are already i n u s e ; h o w e v e r, i t s h o u l d b e a p p l i e d a t a l a r g e r s c a l e a n d m o r e w i d e l y. Construction quality measures how a particular work meets the demanded requirements of that project. Durability is a quantifiable indicator informing us of the extent to w h i c h a ma t e r i a l ma i nt a i n s i t s o r i g i na l r e q u i r e m e nt s . E v i d e nt l y, t h e g r e a t e r t h e ma t e r i a l d u ra b i l i t y, t h e l o w e r t h e t i m e a n d r e s o u r c e s r e q u i r e d t o ma i n t a i n i t b e c o m e s .

PHYSICS AND TECHNOLOGY In the case of some assets, it is assumed that through their service life they shall r e c e i v e pr o p e r ma i nt e na nc e . Howe v e r, i n t he c o n s t r u c t i o n i n d us t r y, t h i s i s n o t t h e c a s e a n d buildings are not catered for maintenance. With some exceptions, for example, an oil rig placed in the Nor th Sea has a guaranteed ser vice life. Buildings are rarely demolished due to a performance failure but instead, their value to owners or tenants has declined, classif ying them as unsuitable or unwanted. Same goes with cars; the second-hand car industr y is big and growing, not because the car cannot function anymore, but because the first owner wants it replaced due to personal and s o c ia l r e as o ns . Mo r e o v e r, e l e c t r i c c a b l e s could technically last for years, but due to population growth and those who are hungry f o r t h e l a t e s t t e c h n o l o g y, o l d e r c a b l e s mus t transmit power beyond the original design l o a d , m a k i n g i t u n s u i t a b l e . We u s u a l l y d i s c a r d our fridge because it is a few millimetres short of lubricants in small bearings in fridge compressors. Howe v e r, replacing compressors can be labour-intensive as they are designed to be sealed and not replaced. As we are aiming to reduce metal demand, we must start identif ying the areas likely to fail and start designing the products so that there is a simple and common m e a n s t o r e p l a c e t h e f a i l e d p a r t s o n l y. Due to the imminent danger related to environmental issues and growing public awareness, governments around the world have been forced to implement stricter environmental policies that have successfully driven some changes. Un d o u b t e d l y, t h e s e force organisations to play a greater role in recycling activities, regardless of costs. R e ga r d i n g m e t a l s us t a i na b i l i t y, i n d e v e l o p i n g and underde veloped countries , 1-2% of the population makes a living by picking recyclable waste to sell - an area not often looked at with much significance. In fact, the efficiency of waste collection is so high that hardly any metal will go to the landfill. Although much of today â€™s waste-picking activities remain unregulated or non-formalised, international organisations have been working to formalise and organise these waste-pickers. The importance of a comprehensive policy framework to address the issue of recycling a c t i v i t i e s a n d m e t a l r e c y c l i n g , i n p a r t i c u l a r, c a n not only enhance employment opportunities but also promote a cleaner environment.

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CONCLUSION In this article, we have explored ways of addressing material sustainability divided into two sections: material design and m a t e r i a l r e u s e . U n d e r ‘ M a t e r i a l D e s i g n ’, we discovered the reason for materials not being used to their full potential: manufacturing simplicity and overspecification. Regarding the reasons explored, we consider potential solutions to maximise material usage, including adapted engineering designs and newly invented technologies. Then moving onto the second method of achieving material e f f i c i e n c y , t i t l e d ‘ M a t e r i a l R e u s e ’, w e l e a r n t about the metal recycling processes and what limits the lack of material recycling i n t h e c o n s t r u c t i o n i n d u s t r y. We a l s o investigated how just by extending the p r o d u c t ’s l i f e e x p e c t a n c y, w e c a n a c h i e v e a large decrease in carbon emissions. To c o n c l u d e , t h e r e a r e m a n y i n g e n i o u s and innovative ways to reduce material usage, but whether or not they are adopted depends heavily on many other factors. In the future, material demand, especially metals, will only ever increase. We n o t o n l y n e e d t o s t a r t r e s e a r c h i n g ways to meet these demands but also need conscientious people to carry out the plans a n d t h i n k f o r t h e b e t t e r m e n t o f s o c i e t y. Regarding the reduction of global carbon footprints, material sustainability has much potential. As scientists, engineers, and conservationists, we need to find ways to overcome the many limitations material sustainability has brought and will bring to us and, on top of that , pave new paths for the generations to come.

PHYSICS AND TECHNOLOGY

Bibliography A b b e y, To n y. “ W h a t I s To p o l o g y Optimization and Why Is It Useful?” P T C , P T C , 2 7 Ju l y 2 0 2 0 , w w w. p t c . com/en/blogs/cad/what-is-topologyoptimization. “A b s o l u t e Z e r o . ” U K F I R E S , u k f i r e s . org/absolute-zero/. Admin, Abbeysteel. Abbeysteel™ and Shearing Co Ltd - Steel Stockholder a n d S u p p l i e r o f C u t S t e e l B l a n k s , w w w. abbey-steel.co.uk/welcome/. A l l w o o d , Ju l i a n M . , e t a l . S u s t a i n a b l e Materials: with Both Eyes Open. UIT Cambridge, 2012. “ B e a m a n d Tr u s s B r i d g e s . ” B r i g h t H u b E n g i n e e r i n g , 8 M a r. 2 0 1 0 , w w w. b r i g h t h u b e n g i n e e r i n g. c o m / s t r u c t u r a l engineering/65884-construction-ofbeam-and-truss-bridges/. Buildsum. (2014, May 03). Why use r e i n f o r c e m e n t i n C o n c r e t e . Re t r i e v e d D e c e m b e r 0 3 , 2 0 2 0 , f r o m h t t p s : / / w w w. youtube.com/watch?v=vuZcPTp51Zk B u r j K h a l i f a : Ta l l e s t B u i l d i n g i n t h e Wo r l d - M e g a S t r u c t u r e s N a t i o n a l Geographic. (2016, August 04). Re t r i e v e d D e c e m b e r 0 3 , 2 0 2 0 , f r o m h t t p s : / / w w w. y o u t u b e . c o m / watch?v=xsVUsk82Qtw C o l l i n s , D. , S a y s , A . , & A z a m . ( 2 0 1 9 , November 29). Stiffness and def lection: Mechanical properties of materials. Re t r i e v e d D e c e m b e r 0 3 , 2 0 2 0 , f r o m h t t p s : / / w w w. l i n e a r m o t i o n t i p s . c o m / mechanical-properties-of-materialsstiffness-and-deflection/ C o o p e r, D a n i e l R . , a n d Ju l i a n

M. Allwood. “The Influence of Defor mation Conditions in Solid-State A l u m i n i u m We l d i n g P r o c e s s e s o n t h e Re s u l t i n g We l d S t r e n g t h . ” Jo u r n a l o f M a t e r i a l s P r o c e s s i n g Te c h n o l o g y, v o l . 2 1 4 , n o. 1 1 , 2 0 1 4 , p p. 2 5 7 6 – 2 5 9 2 . , doi:10.1016/j.jmatprotec.2014.04.018. D u n a n t , C y r i l l e F. , e t a l . “ O p t i o n s t o M a k e S t e e l Re u s e P r o f i t a b l e : A n Analysis of Cost and Risk Distribution a c r o s s t h e U K C o n s t r u c t i o n Va l u e C h a i n . ” Jo u r n a l o f C l e a n e r P r o d u c t i o n , E l s e v i e r, 1 5 Fe b . 2 0 1 8 , w w w. sciencedirect.com/science/article/pii/ S0959652618304542. Gaille, Louise. “13 Beam Bridge Pros a n d C o n s . ” V i t t a n a . o r g , 1 9 M a r. 2 0 1 8 , vittana.org/13-beam-bridge-pros-andcons. M i l l e r, B r a n d o n . “ 1 4 Tr u s s B r i d g e s Advantages and Disadvantages.” Green G a r a g e , 2 7 M a r. 2 0 1 9 , g r e e n g a r a g e b l o g. org/14-truss-bridges-advantages-anddisadvantages. Wo r l d E c o n o m i c Fo r u m . ( 2 0 1 6 , Fe b r u a r y 19). Self-healing concrete for lowcarbon infrastructure | Abir AlTa b b a a . Re t r i e v e d D e c e m b e r 0 3 , 2 0 2 0 , f r o m h t t p s : / / w w w. y o u t u b e . c o m / watch?v=8QXVwU82wrw S e r g e n t , Fr a n . “ M a t e r i a l D e m a n d Re d u c t i o n i n B u i l d i n g s . ” T h e U s e L e s s G r o u p , 8 A p r. 2 0 1 9 , w w w. u s e l e s s g r o u p . org/research/buildings. Ye l l i s h e t t y, M o h a n , e t a l . “Environmental Life-Cycle Comparisons o f S t e e l P r o d u c t i o n a n d Re c y c l i n g : Sustainability Issues, Problems and Prospects.” Environmental Science & Po l i c y, v o l . 1 4 , n o . 6 , 2 0 1 1 , p p . 6 5 0 – 663., doi:10.1016/j.envsci.2011.04.008.

Biology and Chemistr y

Illustration by Reika Oh

BIOLOGY AND CHEMISTRY

Psychedelics: Voodoo or Science? Warren Zhu

What images pop out when you hear L SD, DMT and Magic Mushrooms?

Hippies running around naked with flowers around their neck ? Or freshmen parties streaming with vomit and chants? Ye s , y e s , y e s . T h e r e c k l e s s u s e o f psychedelic drugs is almost invariably tied to the Hippie movement star ting from the 60s, and most have been criminalised since then. Most would silently walk away from the hippies chanting love and peace and sex ; it all seems pretty voodoo and nonsensical. But what if I tell you that psychedelics have been shown to do the following:

1 . Relieve

death anxiety from cancer patients (80% of cancer patients demonstrated clinically significant reductions in anxiety)

2 . Suppress depression 3 . Alleviate alcohol/tobacco

addiction (80% after 6 months, 67% after 1 year for tobacco)

4 . Improve OCD symptoms 5 . Increase the personality

trait of Openness to Experience, which correlates with creativity and empathy

Why do these drugs under the â€˜Psychedelicsâ€™ umbrella have such a huge effect ? Is it just bad science or is there really something behind these infamous Hippie drugs?

BIOLOGY AND CHEMISTRY First , let â€™s look at the chemical structure of psychedelics.

T he Chem ic al Structure

The organic compound tryptamine is common in all psychedelics (See Fig. 1). Tr y p t a m i n e i s o n e of the signalling molecules used between cells in plants, fungi, and animals.

F i g . 1 Tr y p t a m i n e ( C 1 0 H 1 2 N 2 )

Perhaps the most famous of the tr yptamines is the neurotransmitter serotonin. An elevated level of s e r o t o n i n c o r r e l a t e s t o a d e c r e a s e d l e v e l o f a n x i e t y, an elevation in mood, and relief of distress. The tryptamine in the psychedelic compounds has a complementary shape with a serotonin receptor called 5-HT2A , meaning that it can bind to and a c t i vat e t he r e c e pt o r, mi mi c k i ng t he e ff e c t s o f hi g h levels of serotonin. What is more incredible is that LSDâ€™s affinit y to the serotonin receptor 5-HT2A is even better than serotonin itself! It is better than serotonin at fitting into a receptor designed for serotonin!

Illustration by Isabel Chau

BIOLOGY AND CHEMISTRY Effects on the Brain

s o u r c e : h t t p s : / / w e a n d t h e c o l o r. c o m / commissioned-illustrations-by-robbieporter/22382 Our brain is normally pretty rigid. There are a few neural pathways that we use o ft e n, a nd t ho us a nds t hat a r e b a r e l y a c t i vat e d. Howe v e r, und e r t he i nf l u e nc e o f psychedelics, one approaches a semi-dreamlike state, with thousands of novel brain pathways lighting up and uncommon connections forming. In technical jargon, there is an increase of ‘entropy ’ in the brain, making it more disorderly and chaotic. This can yield a plethora of benefits, as it provides a whole host of new thoughts and ideas that normally would not be conjured by oneself. This can be a source of creativity and a way to increase one’s empathy towards others. The leading hypothesis is that these novel connections are being made because o f t h e d e c r e a s e d a c t i v i t y o f a n a r e a o f t h e b r a i n c a l l e d t h e ‘ d e f a u l t m o d e n e t w o r k ’. This includes the medial prefrontal cortex , the posterior cingulate cortex , the hippocampus, the inferior parietal lobe, and the temporal lobe. The ‘default mode network ’ is the part of the brain that causes you to think about all the preps that you haven’ t done and all the lessons that you’re having but don’ t want to have in the middle of an intensely boring lesson; it generates the constant chattering of the mind and is also turned off when skilled meditators are meditating. In this sense, the mind of a person on a psychedelic trip bears resemblance to a person in deep meditation. As the activity of the ‘default mode network ’ decreases, the sense of the self as a separate entit y from the world diminishes too. At this stage, t h e r e i s a s o r t o f ‘ e g o d e a t h ’, i n w h i c h o n e f e e l s c o m p l e t e l y m e r g e d w i t h t h e w o r l d . (Bear with me, I know this sounds pretty voodoo.) This may be the reason for t h e m i ra c u l o us e f f e c t o f p s y c h e d e l i c s o n r e l i e v i n g d e a t h a n x i e t y, a s d e a t h i s t h e d i s s o l u t i o n o f t h e d i s t i n c t b o u n d a r i e s b e t w e e n ‘ t h e m ’ a n d ‘ m e ’, i n w h i c h o n e i s r e turne d t o t he wo r l d as a p i l e o f o rga ni c matt e r, wa i t i ng t o b e d e c o mp o s e d a nd reused. I will elaborate further in the conclusion of the ‘entropic brain hypothesis’ which will help us to conceptualize why psychedelics have these effects.

BIOLOGY AND CHEMISTRY

Illustration by Joy Chen

BIOLOGY AND CHEMISTRY Voodoo or Science? It is clear that the use of psychedelics, especially under professional guidance and advice, can dramatically alter one’s perspective on life and improve o ne ’s q ua l i t y o f l i v i ng. Howe v e r, mo r e research is needed to determine how much of the observed effect comes from psychedelic rather than the placebo effect, and how much is really due to the compound itself. This is evident in how much a psychedelic experience relies on the purposeful creation of an environment that is conducive to its use, and how drastic a difference there is between recreational use of the drug and clinical use of the drug. The effects of psychedelics may partly be attributed to a ‘self-fulfilling prophecy ’ in which one’s expectation for the drug’s effectiveness ultimately makes the drug effective. Some researchers have postulated that psychedelics a r e n o m o r e t h a n a n ‘ a c t i v e p l a c e b o ’, meaning that psychedelics merely assist one in actualising one’s expectation of their effects instead of having any real effects themselves. This is further complicated by the fact that a double-blind controlled experiment is almost impossible to conduct with psychedelics simply because of the uni q u e e ff e c t s o f t he d r ug. Mo r e o v e r, it has always been known that the placebo effect is the strongest in the newest drug due to the mysterious aura surrounding its existence. Considering the mystery surrounding psychedelics and the cultural taboo around psychedelic drugs, the placebo e f f e c t m a y b e e x a g g e r a t e d f u r t h e r.

As you can see, it is all a big hot mess. Howe v e r, t he r e is s t i l l g r e at ho p e a b o u t the effectiveness of psychedelics. For example, one of the leading hypotheses is the ‘entropic brain hypothesis’ which states that because psychedelics increase the entropy (disorder) inside the brain, the brain’s normal way of functioning is disordered and one can jump out of the previous rigid way of thinking. Depression, under this hypothesis, is a mode of operation in which one has trapped oneself within a solely pessimistic view of the world, and addiction, too, is the brain craving for order and returning to its default way of operating.

Perhaps it is fair to say that psychedelics are voodoo and science - where the immeasurable spiritual and materialistic sciences coincide and synthesise. And, at the end of the day, why should we even care, so long as they help and save lives?

BIOLOGY AND CHEMISTRY

Photo by Isabel Chau

BIOLOGY AND CHEMISTRY Bibliography

B a r r e t t , Fr e d e r i c k S . , H o l l i s Ro b b i n s , D a v i d S m o o k e , Je n i n e L . B r o w n , a n d Ro l a n d R . G r i f f i t h s . “ Q u a l i t a t i v e a n d Q u a n t i t a t i v e Fe a t u r e s o f M u s i c Re p o r t e d t o S u p p o r t Pe a k M y s t i c a l Experiences During Psychedelic T h e r a p y S e s s i o n s . ” Fr o n t i e r s i n P h y s i o l o g y 8 ( Ju l y 2 0 1 7 ) : 1 – 1 2 . d o i : 1 0 . 3 3 8 9 / f p s y g. 2 0 1 7 . 0 1 2 3 8 .

C a r h a r t - H a r r i s , Ro b i n L . , Ro b e r t L e e c h , Pe t e r J. H e l l y e r, M u r r a y S h a n a h a n , A m a n d a Fe i l d i n g, E n z o Ta g l i a z u c c h i , D a n t e R . C h i a l v o , a n d David Nutt. “T he Entropic Brain: A Theory of Conscious States Infor med b y N e u r o i m a g i n g Re s e a r c h w i t h P s y c h e d e l i c D r u g s . ” Fr o n t i e r s i n H u m a n N e u r o s c i e n c e 8 ( Fe b. 2 0 1 4 ) : 20. doi:10.3389/fnhum.2014.00020.

B o g e n s c h u t z , M i c h a e l P. , A l y s s a A . Fo r c e h i m e s , Je s s i c a A . Po m m y, C l a i r e E . Wi l c o x , P. C . R . B a r b o s a , a n d R i c k J. S t r a s s m a n . “ P s i l o c y b i n - A s s i s t e d Tr e a t m e n t f o r A l c o h o l D e p e n d e n c e : A Proof-of-Concept S t u d y. ” Jo u r n a l of Psychophar macolog y 29, no. 3 (2015): 289–99. doi:10.1177/0269881114565144. B r e w e r, Ju d s o n . T h e C r a v i n g M i n d : Fr o m C i g a r e t t e s t o S m a r t p h o n e s t o L o v e — W h y We G e t H o o k e d a n d H o w We C a n B r e a k B a d H a b i t s . N e w H a v e n , C o n n . : Ya l e U n i v e r s i t y P r e s s , 2017. B u c k n e r, R a n d y L . , Je s s i c a R . A n d r e w s H a n n a , a n d D a n i e l L . S c h a c t e r. “ T h e B r a i n ’s D e f a u l t N e t w o r k : A n a t o m y, F u n c t i o n , a n d Re l e v a n c e t o D i s e a s e . ” A n n a l s o f t h e N e w Yo r k A c a d e m y o f Sciences 1124, no. 1 (2008): 1–38. doi:10.1196/annals.1440.011. Carbonaro, Theresa M., Matthew P. B r a d s t r e e t , Fr e d e r i c k S . B a r r e t t , K a t h e r i n e A . M a c L e a n , Ro b e r t Je s s e , M a t t h e w W. Jo h n s o n , a n d Ro l a n d R . Griffiths. “Survey Study of Challenging Experiences After Ingesting Psilocybin Mushrooms: Acute and Enduring Po s i t i v e a n d N e g a t i v e C o n s e q u e n c e s . ” Jo u r n a l o f P s y c h o p h a r m a c o l o g y 3 0 , no. 12 (2016): 1268–78. C a r h a r t - H a r r i s , Ro b i n L . , e t a l . “Neural Correlates of the Psychedelic State as Deter mined by fMRI Studies with Psilocybin.” Proceedings of the National Academy of Sciences of the United States of America 109, no. 6 (2012): 2138–43. doi:10.1073/ pnas.1119598109. “Psilocybin with Psychological Support for Tr e a t m e n t - Re s i s t a n t D e p r e s s i o n : A n O p e n - L a b e l Fe a s i b i l i t y S t u d y. ” L a n c e t P s y c h i a t r y 3 , n o . 7 (2016): 619–27. doi:10.1016/S22150366(16)30065-7. C a r h a r t - H a r r i s , Ro b i n L . , M e n d e l K a e l e n , a n d D a v i d J. N u t t . “ H o w D o H a l l u c i n o g e n s Wo r k o n t h e B r a i n ? ” Psychologist 27, no. 9 (2014): 662–65.

Fa d i m a n , Ja m e s . T h e P s y c h e d e l i c E x p l o r e r ’s G u i d e : S a f e , T h e r a p e u t i c a n d S a c r e d Jo u r n e y s . Ro c h e s t e r, V t . : Park Street Press, 2011. G r o b, C h a r l e s S . , A n t h o n y P. B o s s i s , a n d Ro l a n d R . G r i f f i t h s . “ U s e o f the Classic Hallucinogen Psilocybin for Tr e a t m e n t of Existential D i s t r e s s A s s o c i a t e d w i t h C a n c e r. ” I n Psychological Aspects of Cancer: A Guide to Emotional and Psychological C o n s e q u e n c e s o f C a n c e r, T h e i r C a u s e s and Their Management, G r o b, C h a r l e s S . , A l i c i a L . D a n f o r t h , Gurpreet S. Chopra, Mar ycie H a g e r t y, C h a r l e s R . M c K a y, A d a m L. Halberstadt, and George R. G r e e r. “ P i l o t S t u d y o f P s i l o c y b i n Tr e a t m e n t f o r A n x i e t y i n P a t i e n t s with Advanced-Stage C a n c e r. ” Archives of General Psychiatry 68, no. 1 (2011): 71–8. doi:10.1001/ a r c h g e n p s y c h i a t r y. 2 0 1 0 . 1 1 6 . Killingsworth, Matthew A., and D a n i e l T. G i l b e r t . “A Wa n d e r i n g M i n d Is an Unhappy Mind.” Science 330, no. 6006 (2010): 932. doi:10.1126/ science.1192439. M o r e n o , Fr a n c i s c o A . , C h r i s t o p h e r B . Wi e g a n d , E . Ke o l a n i Ta i t a n o , a n d Pe d r o L . D e l g a d o . “ S a f e t y, To l e r a b i l i t y, and Ef ficacy of Psilocybin in 9 Patients w i t h O b s e s s i v e - C o m p u l s i v e D i s o r d e r. ” Jo u r n a l o f C l i n i c a l P s y c h i a t r y 6 7 , n o . 1 1 ( 2 0 0 6 ) : 1 7 3 5 – 4 0 . d o i : 1 0 . 4 0 8 8 / J C P. v67n1110. N o u r, M a t t h e w M . , L i s a E v a n s , a n d Ro b i n L . C a r h a r - H a r r i s . “ P s y c h e d e l i c s , Pe r s o n a l i t y a n d Po l i t i c a l Pe r s p e c t i v e s . ” Jo u r n a l o f P s y c h o a c t i v e D r u g s ( 2 0 1 7 ) : 1–10. P a h n k e , Wa l t e r, “ T h e P s y c h e d e l i c Mystical Experience in the Human Encounter with Death. Harvard T h e o l o g i c a l Re v i e w 6 2 , n o . 1 ( 1 9 6 9 ) : 1–22. P O L L A N, M . ( 2 0 1 9 ) . H O W TO C H A N G E YO U R M I N D : T h e n e w science of psychedelics.

BIOLOGY AND CHEMISTRY

Applications of the Human Microbiome Hanson Wen

I n 2 0 0 7, T h e U n i t e d S t a t e s National Institutes of Health research started a project called the Human Microbiome Project [1], which means from then on, the science community had accepted the human microbiome as an important subject. The human microbiome has been chosen as one of the ten science breakthroughs of the year in 2011 by the Science magazine [2]. Other famous science magazines have also started including the Microbiome section from then on. But what is it? The definition of it in simple terms is all of the microorganisms in a human in a specific area such as skin, lungs, mammary glands, placenta and so on.

The microbiome can take up to 4% of your weight and can do many things. For example, scientists have discovered that humans cannot digest seaweed because no enzymes coded by the human genome can break down the carbohydrates that are tangled with sulfur molecules which are within the plant. But what happens when we eat seaweed? There is a type of marine bacteria (Zobellia galactanivorans) that can digest seaweed, and the same kind of enzyme that these bacteria produce has been found in the human-gut bacteria of Japanese individuals [3]. The microbiome can give us power where we are lacking.

BIOLOGY AND CHEMISTRY

Illustration by Se Lyn Lim

BIOLOGY AND CHEMISTRY The microbiome also aids us in other ways. One of them is that it helps your immune system defend y o u r b o d y. B a c i l l u s s u b t i l i s i s a bacterium that has been found to contribute to the activation of the production of antibodies and other useful molecules to help white blood cells fight i nf e c t i o n [4]. A no t he r a b i l i t y o f microbiomes is that it can affect your emotions, and even affect your brain. A study [5] shows that bacteria in your gut produce 95% of the feel-good hormone, s e r o t o n i n , i n y o u r b o d y. I f y o u extract the gut microbiome of a person in depression and place it in mice, the mice will have symptoms of depression too.

Ho w c a n the m ic ro b io m e affect our emotions? There are three routes to our brain. First is the endocrine s y stem [6]. The hormone s that the bacteria produce can diffuse straight into the blood from the brain. The second route is the vagus nerve [7]. The vagus nerve system can not only go f r o m t h e b ra i n t o t h e b o d y, b u t it can also be bi-directional and go from the body to the brain. Last is the lymphatic system [8]. The microbiome can influence the brain through this system, but this system is also bidirectional. A study shows that gut microbiome inflammation can affect depression and anxiety [9]. These systems, combined, can largely influence the host ’s everyday life, even for things such as choosing what you eat.

As you can see, the microbiome can affect the human body quite a lot, but how can we manipulate the microbiome to help us?

A pplications in Medicine There is an infection called Clostridioides Difficile Infection (CDI). It is caused by a spore-forming bacteria called Clostridioides difficile. It produces s p o r e s i n t h e g u t o f t h e h o s t ’ s b o d y. One way of treating it is to perform a F e c a l M i c r o b i o t a Tr a n s p l a n t a t i o n (FMT ), which is transplanting the gut microbiome of a healthy person to the gut of a person with CDI. FMT is an effective t r e a t m e n t f o r C D I [ 1 0 ] . Tr a d i t i o n a l l y , CDI was treated using antibiotics su c h as va nc o my c i n. Howe v e r, w i t h this method, we have to face the risk of superbugs and also disrupting the balance of the microbiota in the gut. In contrast , FMT restores the beneficial bacterias in the guts, restoring the microbiome, and it also has a high cure rate and low recurrence rate.

A pplications in Sk incare Skincare can be a large market for h u ma n m i c r o b i o m e t e c h n o l o g y, a s microorganisms can significantly affect the skin. [11] “ Physiological effect of a probiotic on skin” shows that S. epidermidis could inhibit acne caused b y P. a c n e s b y f e r m e n t i n g glycerol. [12] Many companies are working on microbiota sk incare [13]; for ex ample , this [14] “ face vinegar ” (See Fig. 1) uses the same principle as the research I have mentioned above. It contains glycerol which can i n h i b i t t h e g r o w t h o f P. A c n e s .

Fig 1. A picture of “face vinegar” [15]

BIOLOGY AND CHEMISTRY

Wild Imagination

For now, these are only the cultivated applications of the human microbiome, but as this technology develops, it will change how we live. This is a wild imagination of the future as this technology develops.

Photo by Isabel Chau

BIOLOGY AND CHEMISTRY

Yo u o p e n y o u r g r o g g y e y e s , l u g yourself off the bed and drag your body to the kitchen. The coffee maker screeches so you pick it up a n d a d d c o f f e e p o w d e r . Yo u t h e n a d d a small packet of gooey stuff into it. It dissolves into your hot coffee a n d a s y o u d r i n k i t . Yo u c a n f e e l t h e smooth lubricating feeling of the coffee going down your throat. The microorganisms in the packet stick to your throat, keeping your throat moisturised for 2 hours. As it finally touches down on the stomach, the rest of the living organism reaches your gut. It slowly spreads, causing a nice warm feeling in your body that makes you happy for the rest o f t h e d a y . Yo u a r e o n y o u r w a y t o work and touch the sticky handle of the metro. There are harmful bacteria that cause flu if it gets in your body fluid. The micro-hand sanitizer you applied this morning is coming into effect. The microbiome is attacking the harmful germs, and your hands turn blue because the signalling bacteria is notif ying you when there is a battle going o n . Yo u r e a l i z e i t a n d q u i c k l y s p r a y disinfectant alcohol on your hands. Un f o r t u na t e l y, s o m e o f t h e b a c t e r i a survived the alcohol. It managed to get into your mouth because you were going to be late and ended up eating your breakfast in your working space. The immune system is actively killing the germs, while

the bacteria in your mouth signals the immune system to produce more antibodies. After 5 hours of work , the bacteria is finally killed, and your microbiome and immune system prevent you from catching the flu. However during the fight , you arrived at the office, and while you were picking up the stack of paper on your desk , you accidentally got a p a p e r c u t . Yo u g o t o t h e f i r s t a i d b o x a n d t a k e o u t a f l a t p l a s t i c c y l i n d e r. It contains microorganisms that can heal your wound in a matter of hours. As you place this cylinder on your wound, the fungus gets into action. It builds a bridge across t h e w o u n d , t h e n p u l l s i t t o g e t h e r. Then the fungi form a solid structure. They then self-destruct. Yo u t a k e t h e p l a s t i c c y l i n d e r o f f and wait for your wound to heal. To n i g h t , as you s howe r, the shampoo you use contains the microbiome which inhibits oil and k e e p s y o u r h a i r h e a l t h y. T h e s h o w e r gel contains anti-odour organisms and the toothpaste inhibits odour and kills germs in your mouth. That is a normal day of a person living in a highly microbiome developed s o c i e t y. I t i s n o t c e r t a i n i f t h i s w i l l ever happen to us, but there is lots of potential in the applications of the Human Microbiome.

That is a normal day of a person living in a highly microbiome developed society. It wonâ€™t be certain if this will ever happen to us, but there is lots of potential in the applications of the Human Microbiome.

BIOLOGY AND CHEMISTRY Bibliography [ 1 ] “ H u m a n M i c r o b i o m e P r o j e c t . ” Wi k i p e d i a , Wi k i m e d i a Fo u n d a t i o n , 1 0 A p r. 2 0 2 0 , e n . w i k i p e d i a . o r g / w i k i / H u m a n _ M i c r o b i o m e _ P r o j e c t . [ 2 ] C o h e n , J. , e t a l . “ B r e a k t h r o u g h o f t h e Ye a r, 2 0 1 1 . ” S c i e n c e / A A A S | S p e c i a l I s s u e : B r e a k t h r o u g h o f t h e Ye a r, 2 0 1 1 , 2 0 1 1 , w w w. s c i e n c e m a g. org/site/special/btoy2011/. [ 3 ] Ke i m , B r a n d o n . “ G u t B a c t e r i a G i v e S u p e r S e a w e e d - D i g e s t i o n Po w e r t o Ja p a n e s e . ” Wi r e d , C o n d e N a s t , 4 Ju n e 2 0 1 7 , w w w. w i r e d . com/2010/04/sushi-guts/. [4] “B Subtilis Probiotic – Why Is It Useful?” Bacillus Subtilis P r o b i o t i c B e n e f i t s - P r o b i o t i c s . o r g, p r o b i o t i c s . o r g / b a c i l l u s - s u b t i l i s / . [ 5 ] Fe a t u r e d N e u r o s c i e n c e P s y c h o l o g y · Ju n e 6 , 2 0 2 0 , e t a l . “ H o w G u t Bacteria Negatively Influences Serotonin and Blood Sugar Levels.” Neuroscience News, 17 Sept. 2019, neurosciencenews.com/gutbacteria-serotonin-blood-sugar-14930/#:~:text=Summary%3A%20 A%20new%20study%20shows,serotonin%20levels%20causes%20 metabolic%20problems. [6] C;, Rastelli M;Cani PD;Knauf. “The Gut Microbiome Influences H o s t E n d o c r i n e F u n c t i o n s . ” E n d o c r i n e Re v i e w s , U. S . N a t i o n a l L i b r a r y of Medicine, pubmed.ncbi.nlm.nih.gov/31081896/. [ 7 ] B o n a z , B r u n o , e t a l . “ T h e Va g u s N e r v e a t t h e I n t e r f a c e o f t h e M i c r o b i o t a - G u t - B r a i n A x i s . ” Fr o n t i e r s i n N e u r o s c i e n c e , Fr o n t i e r s M e d i a S . A . , 7 Fe b. 2 0 1 8 , w w w. n c b i . n l m . n i h . g o v / p m c / a r t i c l e s / PMC5808284/#:~:text=The%20microbiota%2C%20the%20gut%2C%20 and,afferent%20and%2020%25%20efferent%20fibers. [ 8 ] Ts u n o d a , I k u o . “ L y m p h a t i c S y s t e m a n d G u t M i c r o b i o t a A f f e c t Immunopathology of Neuroinflammatory Diseases, Including Multiple S c l e r o s i s , N e u r o m y e l i t i s O p t i c a a n d A l z h e i m e r ’s D i s e a s e . ” C l i n i c a l & E x p e r i m e n t a l N e u r o i m m u n o l o g y, U. S . N a t i o n a l L i b r a r y o f M e d i c i n e , A u g. 2 0 1 7 , w w w. n c b i . n l m . n i h . g o v / p m c / a r t i c l e s / P M C 5 7 0 3 5 9 8 / . [ 9 ] Pe i r c e , Ja s o n M . , a n d K a r i n a A l v i ñ a . “ T h e Ro l e o f I n f l a m m a t i o n a n d t h e G u t M i c r o b i o m e i n D e p r e s s i o n a n d A n x i e t y. ” Wi l e y O n l i n e L i b r a r y, Jo h n Wi l e y & S o n s , L t d , 2 9 M a y 2 0 1 9 , o n l i n e l i b r a r y. w i l e y. c o m / d o i / 1 0 . 1 0 0 2 / j n r. 2 4 4 7 6 . [ 1 0 ] N o o d , E l s v a n , e t a l . “ D u o d e n a l I n f u s i o n o f D o n o r Fe c e s f o r Re c u r r e n t C l o s t r i d i u m D i f f i c i l e : N E J M . ” N e w E n g l a n d Jo u r n a l o f M e d i c i n e , 3 1 Ja n . 2 0 1 3 , w w w. n e j m . o r g / d o i / 1 0 . 1 0 5 6 / N E J M o a 1 2 0 5 0 3 7 . [ 1 1 ] M u i z z u d d i n N ; M a h e r W; S u l l i v a n M ; S c h n i t t g e r S ; M a m m o n e T; “ P h y s i o l o g i c a l E f f e c t o f a P r o b i o t i c o n S k i n . ” Jo u r n a l o f C o s m e t i c S c i e n c e , U. S . N a t i o n a l L i b r a r y o f M e d i c i n e , p u b m e d . n c b i . n l m . n i h . gov/23286870/. [ 1 2 ] D. B l a n k - Po r a t , T. G r u s s - F i s c h e r, e t a l . “ S t a p h y l o c o c c u s E p i d e r m i d i s i n t h e H u m a n S k i n M i c r o b i o m e M e d i a t e s Fe r m e n t a t i o n to Inhibit the Growth of Propionibacterium Acnes : Implications of P r o b i o t i c s i n A c n e Vu l g a r i s . ” A p p l i e d M i c r o b i o l o g y a n d B i o t e c h n o l o g y, S p r i n g e r B e r l i n H e i d e l b e r g, 1 Ja n . 1 9 7 0 , l i n k . s p r i n g e r. c o m / article/10.1007/s00253-013-5394-8. [ 1 3 ] “ 3 5 M i c r o b i o m e S k i n c a r e P r o d u c t s . ” Tr e n d H u n t e r. c o m , T R E N D H U N T E R I n c . , 1 9 Fe b. 2 0 1 9 , w w w. t r e n d h u n t e r. c o m / s l i d e s h o w / microbiome-skincare. [ 1 4 ] “ H i b i s c u s Vi n e g a r To n e r s . ” Tr e n d H u n t e r. c o m , T R E N D H U N T E R I n c . , 2 9 Ja n . 2 0 1 9 , w w w. t r e n d h u n t e r. c o m / t r e n d s / f a c e - v i n e g a r. [ 1 5 ] “ Fa c e Vi n e g a r 2 0 0 m l . ” K n o w To G l o w, k n o w t o g l o w. c o m / p r o d u c t s / face-vinegar-200ml.

BIOLOGY AND CHEMISTRY

FUTURE OF FARMING Edward Wei

The Food Crisis

The current population of t h e w o r l d i s 7. 7 b i l l i o n , a n d this is due to rise to 9.3 billion in 2050; the urban p o p u l a t i o n f r o m 4 .1 t o 6 . 3 billion; the world will require 70% more food than it did i n 2 0 0 9. S i m i l a r l y, a s g l o b a l demand for food increases, our worldâ€™s food production a l s o c o nt i n u e s t o f a c e a t h r e a t o f l i m i t e d wa t e r s u p p l y, scarce land and climate change. A limitation on these resources means that 90% of crop production is e x p e c t e d t o b e f r o m h i g h e r y i e l d s a n d c r o p i nt e n s i t y, and only 10% from the expansion of culturable land ( P l a n t F a c t o r y , 2 0 2 0 ) . Tr a d i t i o n a l o p e n f i e l d f a r m i n g methods are no longer efficient enough to provide for the worldâ€™s demands. This article discusses why we need a new method of farming and an outline of the method.

Illustration by K a y a n Ta m

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Why Not Conventional Farming?

Conventional farming is becoming increasingly more arduous and unsuitable to carr y out due to several trends: climate change, the lack of agrochemicals, a ballooning carbon footprint and a labour shortage crisis.

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Climate Change

Growing crops on an open field always comes with risks - the yield and quality depend on weather conditions and seasons, so there is no reliable nor stable supply of plant-grown food. This is especially significant when considering the effects of climate change: rising temperatures and more frequent extreme weather cases can lead to lower yield or even making the environment inhospitable for cer tain crops. When the latter scenario is reached, farmers will have a difficult time adapting to alternative crops to grow as they lack the experience and knowledge t o g r o w s u c h c r o p s e f f e c t i v e l y. Extreme weather conditions like flooding or droughts can harm crops and reduce yield. US farmers already spend 11 billion dollars annually fighting weeds that compete with crops for light , water and nutrient s [3]. This is due to increase as warmer temperatures, wetter climates, and an increase in CO2 levels stimulate the growth of pests, weeds and fungi. A greater population of pests requires an increase in the use of pesticides to combat them, which is detrimental to human health. Desertification and to a lesser extent urbanisation - is taking arable land away from farmers. The UN suggests that 12 million hectares of cultivable land are lost annually due to

droughts and deser tification [5]. Switching to farming in greenhouses can protect the crops from the effects of climate change, but several disadvantages affect e f f i c i e n c y. F i r s t l y, i t i s n o t v e r y energy efficient; as greenhouses depend on natural sunlight , the incident light is not regulated. Apart from not being able to control l i g ht q u a l i t y, t h i s a l s o m e a n s t ha t solar light intensity is often too dim at dawn, sunset and night , a n d o n d a y s w h e r e i t i s c l o u d y, rainy or cold, and too high around noon on sunny days. It is also difficult to regulate temperature and humidity as it is considerably d e p e n d e n t o n s o l a r l i g h t i n t e n s i t y. To m a i n t a i n a n d r e g u l a t e o p t i m a l temperature, greenhouses are often ventilated, but this allows insects and diseases in, obligating the use of pesticides. CO2 levels also cannot be maintained at a high level if ventilated. It is predicted that by 2050, we would lose about 2% of the worldâ€™s fertile land due to rising sea levels and desertification, while freshwater demand will balloon by 55%. If everyone switched to greenhouses to grow crops, the land saved would only just be able to offset the predicted land loss while halving the percentage increase in freshwater demand to 28% [14].

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2. Agrochemicals Spillage and the overuse of agrochemicals can also harm the environment. The term ‘agrochemical’ refers to all the different types of chemicals used to aid farming, such as pesticides, herbicides, fungicide, nematicide, synthetic fertilisers, growth hormones and more. Excessive use of fertilisers leads to the contamination of nitrates in groundwater which can leach into nearby lakes, causing eutrophication, the rapid growth of algae, and the decay of many aquatic lifeforms . Pesticides sprayed onto entire fields using equipment mounted on vehicles like planes and tractors often drift away - some older variants like DDT can remain active for a very long time, contaminating w i l d l i f e , wat e r, f o o d a nd huma ns [2]. Humans are also running out of an essential mineral to plant growth phosphates. Phosphates are the only form of phosphorus that plants can absorb, and they are critical to seed production, root growth, hastening p l a nt ma t u r i t y, s t a l k s t r e n g t h , r o o t rot resistance and resistance to winter kill (NRCS). This is because phosphorus forms part of an e s s e n t i a l c h e m i c a l - AT P ( a d e n o s i n e triphosphate) responsible for the storage and transfer of energy throughout the plant. While phosphate minerals are not “used up” like fossil fuels, our method of applying it to crops causes it to disperse throughout the environment making them difficult to retrieve and reuse. Thus, several reports have warned that global reserves will be depleted within the next 50 years or so.

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3. Carbon Emissions Conventional farming has quite a large carbon footprint. For most cities, the demand for food dramatically exceeds what is and can be cultivated in the surrounding region; thus, they import their food from large global supply chains with massive carbon footprints. The higher proportion of the population gaining access to electricity means more usage of refrigerators, supporting the trend of buying imported food. One study found that the transportation of ordinary and small c o m m e r c i a l t r u c k s a r e 0 . 8 k g a n d 1 . 9 k g - C O 2/ t o n o f f o o d / k m on average, with carbon emissions from cargo ships being lowest and aeroplanes having the highest. Additional CO2 is emitted when food is cooled (which it often needs to be). Food in a supermarket in the USA travels on average 2000 km between production and consumption sites [9]. Despite all of this, the most significant contributor to the agriculture sector â€™s carbon footprint is not the transportation of food, but rather deforestation to provide land for the crops. A study showed that tropical deforestation for agriculture and tree plantations releases 2 .6 Gt of CO2 per year [9].

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Labour Shortage Crisis There is a labour shortage crisis occurring i n t h e a g r i c u l t u r a l s e c t o r. A n i n c r e a s i n g proportion of the population living in urban areas means fewer people are working on farms. This is driven by the growing role of supermarkets and TNCs in supplying food driven by urbanisation. These organisations favour large agricultural producers, leading to a shift in employment in the food sector: fewer people are working in agriculture and more in retailing, food vending, wholesaling, transport and food processing [8 ]. A d d i t i o na l l y, c o u nt e r -u r b a n i s a t i o n , t h e migration of people from urban areas to rural areas, effectively leads to the urbanisation of the rural regions - services and facilities are built so people working on farms can switch jobs to work in those new places o f e m p l o y m e n t w h i c h g i v e h i g h e r p a y. T h i s is all spurred on by the lack of interest in farming amongst the younger generation - in the US, only 9% of farmers are below the age of 35 [1]. This leads to reduced crop yields, crop intensity and changes in traditional cropping patterns. The latter could mean a loss in crop diversity; this can be seen in Bangladesh which has lost more than 7000 types of landraces over time. Many of these crops were pest resistant , tolerant to salinity and able to be grown in many different environments, as well as having medical properties, great taste and high nu tritional value s [6].

BIOLOGY AND CHEMISTRY

Farming in the 21st centur y

To f u l f i l t h e f o o d r e q u i r e m e n t s o f t h e f u t u r e , t h e n e w agricultural cultivation technique has to achieve much higher yields, while simultaneously protecting the environment, improving health and driving economic d e v e l o p m e nt s . T h i s n e w f a r m i n g t e c h n i q u e c a l l e d “ Ve r t i c a l F a r m i n g ”, f o u n d e d i n 1 9 9 9 b y D i c k s o n D e s p o m m i e r a n d his students, could be a possible amelioration to the w o r l d ’ s f o o d c r i s i s . Ve r t i c a l f a r m i n g i s t h e c o n c e p t o f g r o w i n g f r u i t s a n d v e g e t a b l e s i n m u l t i p l e l a y e r s . Ve r t i c a l farming has four main types: skyscraper farms, wall and roof farms, vertical greenhouses and plant factories.

BIOLOGY AND CHEMISTRY

Skyscraper Farms

F i g 1 . P i c t u re o f a S k y s c r a p e r Fa r m S o u r c e : “ T h i s I s W h y We S h o u l d Be Far ming in Skyscraper s.” City M o n i t o r, 2 6 M a y 2 0 1 5 , c i t y m o n i t o r. ai/environment/why-we-should-befarming-skyscrapers-1029.

Wall and Rooftop Farms

Fig. 1 is likely the first picture to come to mind when you hear the term “ vertical farming” - massive skyscrapers containing pastures full of vegetables, fruits, trees and even animals. While images such as above are aesthetically p l e a s i n g , i n r e a l i t y, s k y s c ra p e r s farms are likely the least viable of the four types. Skyscrapers are expensive real estate; thus, it is usually reser ved for high-value economic activities. Cultivation of crops or humane rearing of animals has low-value densit y - profitable when the context is the countryside where the land is bountiful and cheap, but not when using premium real estate, even if you grow highvalue crops. A d d i t i o na l l y, the cost of growing scales with the height of the building - pumping water and vertically moving phytomass takes considerable energy and increases the cost.

In contrast with skyscraper farms, wall and rooftop farms do not take up valuable real estate, but rather aim to utilise u n u s e d s p a c e s t o g r o w f o o d . Wa l l a n d r o o f t o p f a r m s a d d v i s u a l appeal to urban areas and can also be useful in combating the urban heat island effect. An urban heat island is a metropolitan area that is significantly warmer than its surrounding rural areas due to human activities. Moderating this effect can i m p r o v e a i r a n d wa t e r q u a l i t y, a s t h e e f f e c t h e a t s t h e wa t e r that drains into sewers and is released into lakes and rivers, r e d u c e s d e a t h s d u e t o e x t r e m e h e a t a n d s a v e s e l e c t r i c i t y. T h i s investigation found that wall and rooftop farms can be 30 to 40 degrees Fahrenheit lower than conventional rooftops and mi ni mis e e ne rg y us e b y 0. 7 % [11 ]. Howe v e r, t he o v e ra l l i mpa c t gained from wall and rooftop farms is negligible. Despommier and his students went on to calculate that rooftop farms w o u l d o n l y b e a b l e t o s u p p l y 2 % o f N e w Yo r k ’ s p o p u l a t i o n in 2015 even when fully utilising every one of its rooftops.

BIOLOGY AND CHEMISTRY

Vertical Greenhouses

Ve r t i c a l g r e e n h o u s e s a r e l a r g e t r a n s p a r e n t boxes that grow crops in multiple levels. This creates an immediate problem with lighting, as the glass or polymer structure already absorbs a fraction of the light spectrum and the stacked layers create shadows. The solution is to rotate levels vertically to ensure even sunlight exposure as well as installing artificial lighting. Ve r t i c a l g r e e n h o u s e s t r a d e g r e a t e r c r o p d e n s i t y with higher capital costs and electricity costs, making it more fitting for urban environments where land is premium. The vertical greenhouse could play an essential role in solving global challenges as they require 10 to 15 times less land and water than conventional farming. Howe v e r, t he y a r e sub j e c t e d t o t he s a me pr o b l e ms as traditional greenhouses mentioned above.

Plant Factories Plant factories are the most technologically advanced of vertical farms. They are airtight, highly climate controlled, sterile, windowless buildings with stacked layers of plants, growing in hydroponics or aeroponics, relying on 100% artificial lighting. This is the version which this essay will focus mostly on as they have the most significant potential to combat the world food crisis.

https://futuretodayinstitute. com/trend/aeroponics-verticalcultivation-and-indoor-plantfactories/indoor-plant-factories/

BIOLOGY AND CHEMISTRY The world is desperately in need of a methodology to effectively produce highquality foods, improve social welfare and enhance the quality of life with minimum consumption of resources and emission of environmental pollutants . Plant factories have the potential to fulfil this requirement.

Why Plant Factories?

BIOLOGY AND CHEMISTRY How Plant Factories Help Social Welfare

Plant factories enable complete control of the environment. Thus, production is year-round, unaffected by seasons and climate, providing a reliable source of food which prevents prices from fluctuating. This also means that the cultivation of wide varieties of regional crops is possible by adjusting the environment (though this is not possible yet as will be explained later). A d d i t i o na l l y, b e i n g c l o s e d o f f t o t h e o u t s i d e w o r l d trivialises the pesticide usage as the crops are protected from harmful organisms; fruits and vegetables grown in plant factories are not only healthier but also have increased shelf lives as bacterial loads can be 1/100 to 1/1000th of field-grown variants [9]. The use of aeroponics and hydroponics means that only the necessary minerals are present and absorbed by the crops and that heavy metals or pathogens found naturally in the s o i l a r e n o t p r e s e n t , m a k i n g t h e c r o p s m u c h h e a l t h i e r. Fur thermore, plant factories could potentially solve the problem of food deserts. Food deserts are areas that have limited access to cheap and nutritious food. This phenomenon is caused by urbanisation which leads to changes in the demands of food. People in urban areas consume more in general and desire greater food varieties: dairies, meat, fish, processed food, organic vegetables and fast-food [12]. Among these food types, the most concerning is processed foods. Processed foods consist of foods that have additional salt , sugar or fats added into it ; ultra-processed foods take a step beyond, adding artificial colouring, flavours and preservatives, and are often pre-prepared frozen food or microwave food. In par t due to longer working hours and lower prices as well as the growing influence of supermarkets in supplying processed food, the preference for this category of food is very high. One study found that ultra-processed foods comprise about 60% of the total caloric intake in the USA [10]. A d d i t i o na l l y, t ra n s p o r t a t i o n , s t o ra g e a n d r e t a i l s h e l f conditions can have severe repercussions on the quality of food. A study found that in just three days, lettuce stored on retail shelves experienced a 64.6% weight loss overall as well as a 48% loss in ascorbic acid (vitamin C) [7]. The consequences are severe: many urbanites face malnutrition from overconsumption of calorie-dense foods, leading to o b e s i t y, n u t r i e nt d e f i c i e n c i e s a n d i l l n e s s e s . Pl a nt f a c t o r i e s are possible solutions as they can be built near or in urban areas, thus supplying cheaper fresh produce and reducing nutrient loss due to transportation and storage. T h i s i s , h o w e v e r, s t i l l j us t a p o s s i b i l i t y, a s p l a nt f a c t o r i e s are still relatively immature as an industry and most companies are focusing on planting premium crops like kale with higher profit margins to pay back investments.

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BIOLOGY AND CHEMISTRY How Plant Factories Help the Environment

A d d i t i o na l l y, t h e us e o f a e r o p o n i c s a n d h y d r o p o n i c s in vertical farms reduces water consumption per unit of crop grown. The best plant factories produce 1 kg o f l e ttu c e o n j us t 1. 2 L o f wat e r, whi c h is ne a r l y 2 0 0 times less than traditional farming methods (around 237 L). This has vast prospects in heightening water s e c u r i t y, i m p r o v i n g wa t e r q u a l i t y (a s t h e r e i s n o leaching of nutrients) and halting marsh destruction. As mentioned above, plant factories can be built near urban areas, thus reducing greenhouse gas e mis s i o ns f r o m t ra ns p o r t at i o n. Howe v e r, t he mo s t significant impact on reducing carbon footprint stems from how high the crop yields of plant factories are - 2 8 6 k m / m 2/ y e a r c o m p a r e d t o 3 . 9 k m / m 2/ y e a r i n conventional farms [14]. This means that the capacit y in returning land to forests and shrublands is massive.

Current Issues and Potential Improvements The drawbacks There are several main problems with plant factories, and that can all be attributed to one root cause: the cost o f e l e c t r i c i t y. T h e h i g h e n e r g y c o s t s mean that current vertical farms are restricted to only specific types - leaf y greens. They are composed of about 95% water and have a high edible mass percentage, meaning that less energy is needed to produce lots of edible mass. This hinders the positive impact that plant factories have on the environment as they are unable to cultivate staple crops like rice. Rice consists of 19% of t h e w o r l d â€™s c a l o r i e s , b u t , u n f o r t u na t e l y, only contain 15% water and have a much lower edible mass percentage than leaf y greens, requiring 30 times more energy

than lettuce [9], and making them economically unfeasible - any rice grown must have a price tag far above the market price just to break even, so despite their health benefits, a limited number of consumers are willing to buy them. Suppose plant factories can improve to a point where it becomes economically viable to grow staple foods like rice and g r a i n . W e c a n e x p e c t t o r e c l a i m 1 7. 6 % of land and reduce global freshwater consumption by up to 91% [13]. There are two main ways to achieve this goal - by improving the efficiency of the technology used in plant factories and through data collection.

BIOLOGY AND CHEMISTRY

Role of Data Analysis Sensors and data analyses are widely used in plant factories to measure multitudes of variables and their effects on plant growth. Fine-tuning v a r i a b l e s l i k e t e m p e ra t u r e , h u m i d i t y, air composition, air current speed, ion c o n c e nt ra t i o n s , l i g ht i nt e n s i t y, a n d l i g ht spectrum to maximise the efficiency of growth is a substantial part of the journey in bringing staple foods into plant factories. Let â€™s take the example of controlling light. Each plant can absorb different spectrums of light more than others. Thus LED grow lights are being used to emit specific spectrums of light (light recipes) tailored to e a c h p l a n t t o e n h a n c e e f f i c i e n c y. A d d i t i o na l l y, m o s t c r o p s us e c ha n g e s in sunlight to determine when to grow a n d f l o w e r. B y e m i t t i n g d i f f e r e n t l i g h t

recipes at opportune moments, we can lengthen flowering periods to increase the size of the plant, decrease the root growth phase to increase the edible mass percentage (due to usage of aeroponics and hydroponics, crops donâ€™ t need large and complex root systems to absorb enough nutrients) and even a l t e r t he t as t e , s ha p e , c o l o ur, a nd texture of a plant. The extent of change is considerable: field-grown plants tend to have an edible mass percentage of 40% while crops grown in plant factories can achie ve 92% [13]. Fur thermore , by omitting certain unnecessary growth phases, one can also reduce growth time by a sizable amount - about 1020 times per year [9]. This not only increases yield but also increases data collection, as many more experiments can be done in the same period.

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BIOLOGY AND CHEMITRY Role of Genetics Apart from the use of computer science, we can also improve efficiency by using genetic engineering to make higher yield crops and select different variants of staple crops that are more suitable to plant factory environments, such as those with a higher edible mass p e r c e n t a g e a n d s h o r t e r h e i g h t s . We c a n a l s o b r e e d o r genetically modif y existing crops for faster harvest cycles.

R o le o f Te c hno lo g ic a l Advancements Te c h n o l o g i c a l a d v a n c e m e n t s s u c h a s c h e a p e r g e n e editing techniques, automation, accurate sensors, and better LED lights can all significantly increase yield. For example, more efficient LED lights emit less waste heat , which saves electricity and allows the lights to be placed closer to the plant without risking heat damage, improving c r o p d e n s i t y. T h i s a l s o m e a n s t h a t m o r e l i g h t e m i t t e d i s being absorbed by the plants, decreasing the amount of e n e r g y w a s t e d . Ye a r b y y e a r , m o r e a d v a n c e d L E D l i g h t s c a n emit a broader range of the light spectrum, giving more flexibility in manipulating growth cycles and increasing yield. They are also getting cheaper and having longer l i f e s pa ns . Mo r e o v e r, w i t h d e c r e as i ng c o s t s p e r watt o f various forms of renewable energies, we can increase profitability while reducing the environmental impact of plant factories. The technology-rich environment is also a t t r a c t i n g t h e y o u n g e r g e n e r a t i o n i n t o t h e f a r m i n g i n d u s t r y.

BIOLOGY AND CHEMISTRY

Conclusion With all the benef it s of plant factories, it is easy to predict that in the upcoming decades, traditional farming will gradually be replaced by plant factories. As technology continues to advance, plant factories will be able to sustain the future population while also protecting the environment, improving health conditions and driving economic development.

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Bibliog raphy [ 1 ] “ ( I n f o g r a p h i c ) T h e U. S . F a r m L a b o r S h o r t a g e . ” A g A m e r i c a , 1 1 M a r. 2020, agamerica.com/the-impact-ofthe-far m-labor-shortage/. [ 2 ] “A g r o c h e m i c a l . ” A g r o c h e m i c a l a n O v e r v i e w | S c i e n c e D i r e c t To p i c s , w w w. s c i e n c e d i r e c t . c o m / t o p i c s / e a r t h and-planetary-sciences/agrochemical. [3] “Climate Impacts on Agriculture a n d Fo o d S u p p l y. ” E PA , E n v i r o n m e n t a l P r o t e c t i o n A g e n c y, 6 O c t . 2 0 1 6 , 19january2017snapshot.epa.gov/ climate-impacts/climate-impactsagriculture-and-food-supply_.html. [4] Djurfeldt, Agnes Andersson. “Urbanization and Linkages to S m a l l h o l d e r Fa r m i n g i n S u b - S a h a r a n A f r i c a : I m p l i c a t i o n s f o r Fo o d S e c u r i t y. ” G l o b a l Fo o d S e c u r i t y, v o l . 4 , 2 0 1 5 , p p . 1–7., doi:10.1016/j.gfs.2014.08.002.

Deforestation Emissions.” Global Environmental Change, Pe rg a m o n , 2 0 M a r. 2 0 1 9 , w w w. s c i e n c e d i r e c t . c o m / s c i e n c e / a r t i c l e / p i i / S 0 9 5 9 3 7 8 0 1 8 3 1 4 3 6 5 # : ~ : t e x t = Tr o p i c a l deforestation for agriculture and tree plantations releases 2.6 GtCO2 y r. & t e x t = 2 9 – 3 9 % of emissions are, mainly in beef and oilseeds.&text=Imported deforestation emissions rival domestic agricultural emissions in many countries. [ 9 ] “ P l a n t F a c t o r y. ” G o o g l e ¹ Ï ® Ñ , Google, books.google.com.hk/ books?hl=zh-TW&lr=&id=z-C7DwAA QBAJ&oi=fnd&pg=PP1&dq=vertical+ f a r m i n g & o t s = z D k f y J g k e v & s i g = Q G G Ta l E w i N 0 w r F z s O Tm q N W D 7 u m U & r e d i r _ esc=y#v=onepage&q&f=false. [ 1 0 ] “ P r o c e s s e d Fo o d s a n d H e a l t h . ” T h e N u t r i t i o n S o u r c e , 2 4 Ju n e 2 0 1 9 , w w w. hsph.harvard.edu/nutritionsource/ processed-foods/.

[5] “The High Price of Desertification: 2 3 H e c t a r e s o f L a n d a M i n u t e - Wo r l d . ” R e l i e f We b , reliefweb.int/re port/ world/high-price-desertification-23hectares-land-minute.

[ 1 1 ] “ U s i n g G re e n Ro o f s t o Re d u c e H e a t I s l a n d s . ” E PA , E n v i r o n m e n t a l P r o t e c t i o n A g e n c y, 1 1 Ju n e 2 0 1 9 , w w w. epa.gov/heatislands/using-greenroofs-reduce-heat-islands.

[6] “Impact of Changing Cropping Pa t t e r n o n Fa r m L a n d . I s I t T i m e t o G o B a c k t o Tr a d i t i o n a l C r o p s ? ” G r a i n m a r t N e w s , 2 1 Ju l y 2 0 2 0 , w w w. g r a i n m a r t . i n / news/impact-of-changing-croppingpattern-on-farm-land-is-it-time-togo-back-to-traditional-crops/.

[ 1 2 ] We i s s , A u t h o r

[ 7 ] M a n a g a , M i l l i c e n t G. , e t a l . “ I m p a c t o f Tr a n s p o r t a t i o n , S t o r a g e , a n d Re t a i l S h e l f C o n d i t i o n s o n L e t t u c e Quality and Phytonutrients Losses in the Supply Chain.” Wiley Online L i b r a r y, J o h n W i l e y & a m p ; S o n s , L t d , 4 Ju l y 2 0 1 8 , o n l i n e l i b r a r y. w i l e y. c o m / doi/full/10.1002/fsn3.685. [8] Pe n d r i l l , F lorence, et al. “A g r i c u l t u r a l a n d Fo r e s t r y Tr a d e Drives Large Share of Tr o p i c a l

Ta m a r. “ I n d u s t r i a l A g e F a r m i n g : H o w Urbanization Is Changing the Industry - S t a r t - U p N a t i o n C e n t r a l B l o g. ” S t a r t , 1 6 J a n . 2 0 1 7 , b l o g. s t a r t u p n a t i o n c e n t r a l . org/agritech/industrial-age-farminghow-urbanization-is-changing-theindustry/. [ 1 3 ] “ H o w M u c h C a n Ve r t i c a l F a r m i n g Improve?”, Exa Cognition, 10 Jan 2019, h t t p s : / / w w w. y o u t u b e . c o m / watch?v=qGyAeqdkkbw&t=6s. [14] “Does Ve r t i c a l Fa r m i n g Wo r k ? ” , E x a C o g n i t i o n , 2 6 O c t 2018, h t t p s : / / w w w. y o u t u b e . c o m / watch?v=dnCQuwCtqJg&t=223s

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Mathematics featuring ar ticles fr om the Wor ld Math Competition I n O c t o b e r, s e v e r a l H a r r o w s t u d e n t s competed in the World Mathematics Championships. The following articles were written as part of the Inspiration round where we were instructed to write an essay about how one particular mathematician contributed to 3 of the Sustainable Development Goals (SDGs). The SDGs are 17 interlinked goals intended to be a â€œblueprint to achieve a better and more sustainable future for allâ€?.

Photo by Isabel Chau

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Re al L i f e Applications of Complex Numbers Josiah

Let’s start with the basics. At a young age, we were taught how to count with positive numbers, such as one, two or three. Later in primary school, we were also introduced to negative numbers: for example, -19 is a negative number. I’m also going to assume that you are familiar with square roots (if not, you should revise). It is commonly taught to students that one cannot take the square root of negative numbers. But what if we could? You may be wondering, “How is it possible to take the square root of a negative number?” In fact, mathematicians before the 16th century would’ve thought so as well. This was until Italian mathematician Gerolamo Cardano broke the convention by inventing imaginary numbers, in a desperate attempt to solve cubic equations. Throughout history, mathematicians have always loved to break their own rules: apart from taking the square root of a negative number, Ramanujan once proved that 1 + 2 + 3 + 4… all the way up to infinity is equal to -1/12. Another mathematician, Georg Cantor, proved that there are as many even numbers as positive integers. Therefore, what Cardano did was not uncommon (at least in historical records).

Photo by Isabel Chau

MATHEMATICS So what is an imaginary number? An imaginary number is a multiple of i = √-1. For example, √-25 is an imaginary number because it can be rewritten as √-25 = √25 × -√1 =5i. Furthermore, one can add a real number to an imaginary number to form a complex number. To demonstrate this, one can add 3, a real number, to 3i, an imaginary number, to form the complex number 3+3i.

Illustration by Ethan Lan A common visualisation of complex numbers is the use of Argand Diagrams. To construct this, picture a Cartesian grid with the x-axis being real numbers and the y-axis being imaginary numbers. An important property of complex numbers is the Euler’s formula: it states that every complex number, can be rewritten in the form of re =r(cos + i sin ), where e=2.71828... is the Euler’s constant, r is the ‘distance’ of the complex number from the origin and is the angle of the complex number from the positive real axis (anticlockwise, in radians). On the left is an illustration of this. Euler’s formula is described to be the most beautiful mathematical result in history by many mathematicians. Its aesthetic beauty lies in the fact that it implies a magical relationship between real numbers and imaginary numbers. Although I would like to demonstrate the elegant proof for this formula, it is unfortunately outside the scope of this article.

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Applications

Illustration by Ethan Lan

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Signal Processing Suppose a pianist is recording in a music studio. He invites you to a game - to guess what musical notes he plays without looking at the piano. As someone who doesn’t have perfect pitch (the ability to tell what musical note it is just by hearing), how would you win this game? It turns out, there is a way to always deduce what notes he is playing without cheating. Firstly, record his playing in an audio-editing software. The software will store the recording in a waveform.

One can then apply Fourier Transform to the waveform signal to figure out which frequencies are the most prevalent within the recording. This can be shown by deducing the ‘peaks’ in the resulting frequency distribution after Fourier Transform has been applied.

As there are evident peaks at 256 Hz and 391 Hz (which correspond to C4 and G4, respectively), we can therefore deduce that the pianist must have played C and G on the piano.

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MATHEMATICS Knowing the locations of peaks is incredibly important to audio-editors and music producers. They can not only derive the source of any background noise but also use its frequency as a reference to eliminate them through the means of Equalisation (EQ). The idea behind the Fourier Transform is rather genius; it proposes that any complicated wave can be decomposed into multiple sinusoidal waves with varying frequencies. What Fourier Transform does is that it predicts which frequency is likely to be equivalent to one of such sinusoidal waves. It does this by ‘wrapping’ the wave around the origin in the complex plane and computing the sum of complex coordinates of all possible points on the wrapped wave.

AC Circuit Analysis Complex numbers are also utilised in calculations of current, voltage or resistance in AC circuits (AC stands for Alternating Current, which is a current that changes magnitude and direction over time). A common application of complex numbers (more specifically, Euler’s formula) is to compute the potential difference across two AC power supplies with respect to time. On the right is an example of such a calculation.

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MATHEMATICS To find the combined potential difference, simply adding VA and VB together will not work. However, we can express both voltages as the Real Part (x-coordinate on the Argand Diagram) of a complex number.

*It is conventional to use j instead of i to represent imaginary numbers in circuit analysis, to avoid confusion with current (which its symbol is i or I).

We can then add the complex numbers and factorise:

Furthermore, complex numbers are also used to express the magnitude and phase of impedance in an AC circuit. Impedance is very similar to resistance - it slows down the electrons in the circuit. The distinction is that impedance causes a phase shift on the electrical current, while resistance does not. Impedance takes place in common electrical components such as inductors and capacitors, and so having a complex number representation is crucial.

In general, complex numbers serve as a representation of phase, which is essential to analysing AC circuits.

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Quantum Mechanics

Quantum Mechanics is a field of Physics that deals with the motions and interactions between subatomic particles - mainly Bosons (e.g. a photon) and Fermions (e.g. a neutron). It provides a mathematical description of their behaviour in terms of probabilities. In fact, complex numbers form the fundamental basis of Quantum Mechanics.

One main area of concern in Quantum Mechanics is to find the wave function of a subatomic particle. A wave function, simply put, is a complex probability distribution indicating the possible positions of the particle on a specific time. A fundamental formula in Quantum Mechanics, in which the role of the wave function is significant, is the Schrödinger Equation:

The importance of the Schrödinger Equation to Quantum Mechanics is analogous to that of Newton’s Second Law to Classical Physics; they both provide a sensible mathematical prediction of a particle’s position and momentum. The system of complex numbers is essential to the field because it is a convenient language for expressing wave functions without breaking the rules.

using the Schrödinger Equation mentioned above. By using the formula, they proved that the two atoms in a hydrogen molecule are, in fact, ‘sharing’ electrons to form what we know as a covalent bond. Immediately after this, several other chemists continued developing their theory of bonding, such as Linus Pauling’s discovery of resonance and orbital hybridisation. In summary, without the development of Quantum Mechanics, scientists wouldn’t be able to discover the electronic structure of atoms, nor be able to come up with the concept of bonding between atoms.

Furthermore, a direct application of Quantum Mechanics is that it accelerated the expansion of Chemistry. In 1927, Walter Heitler (not Hitler!) and Fritz London formulated the Valence Bond Theory

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tion by Ethan

Bibliog raphy S i g n a l P r o c e s s i n g ( Fo u r i e r Tr a n s f o r m ) S t a r, Z a c h . “ T h e M a t h e m a t i c s O f S i g n a l P r o c e s s i n g | T h e Z - Tr a n s f o r m , D i s c r e t e S i g n a l s , A n d M o r e ” . w w w. y o u t u b e . c o m , 2 0 1 9 , h t t p s : / / w w w. y o u t u b e . c o m / w a t c h ? v = h e w Tw m 5 P 0 G g & t = 1 3 5 0 s & a b _ c h a n n e l = Z a c h S t a r. “ Fo u r i e r A n a l y s i s ” . E n . W i k i p e d i a . O r g , 2020, https://en.wikipedia.org/wiki/ Fo u r i e r _ a n a l y s i s . A c c e s s e d 9 N o v 2 0 2 0 . C h a n , J u s t i n . “A p p l i c a t i o n O f F o u r i e r T r a n s f o r m : S i g n a l P r o c e s s i n g ” . w w w. y o u t u b e . c o m , 2 0 1 7 , h t t p s : / / w w w. youtube.com/watch?v=9uv3-m8jkVg&ab_ c h a n n e l = Ju s t i n C h a n . A c c e s s e d 9 N ov 2 0 2 0 . AC Circuit Analysis

Conclusion Although we cannot physically visualise complex numbers, it is difficult to deny its importance to the scientific community. Complex numbers perfectly demonstrate the role of mathematics in science - it acts both as a powerful language to describe complicated phenomenons, and a comprehensive toolkit to solve difficult problems.

C h a n , J u s t i n . “A p p l i c a t i o n O f F o u r i e r T r a n s f o r m : S i g n a l P r o c e s s i n g ” . W w w. Yo u t u b e . C o m , 2 0 1 7 , h t t p s : / / w w w. youtube.com/watch?v=9uv3-m8jkVg&ab_ c h a n n e l = Ju s t i n C h a n . S t a r, Z a c h . “ T h e R e a l W o r l d U s e s O f I m a g i n a r y N u m b e r s ” . W w w. Yo u t u b e . C o m , 2 0 1 8 , h t t p s : / / w w w. y o u t u b e . c o m / w a t c h ? v = _ h 4 9 i l n T m W 4 & t = 6 3 0 s & a b _ c h a n n e l = Z a c h S t a r. “Complex Numbers And Phasors”. Https:// W w w. E l e c t r o n i c s - T u t o r i a l s . W s / , 2 0 2 0 , h t t p s : / / w w w. e l e c t r o n i c s - t u t o r i a l s . w s / accircuits/complex-numbers.html. Johnson, Robert. “Using Complex Number s In Circuit Analysis And Review Of T he Algebra Of Complex Numbers”. 2020, h t t p : / / w w w. i t s . c a l t e c h . e d u / ~ j p e l a b / phys1cp/AC%20Circuits%20and%20 Complex%20Impedances.pdf Quantum Mechanics DeCross, Matt et al. “Schrödinger Equation | Brilliant Math & Science Wiki”. Brilliant. Org, 2020, https://brilliant.org/wiki/ schrodinger-equation/ Accessed 9 Nov 2020. K a r a m , R i c a r d o , e d . b y. W h y A r e C o m p l e x Numbers Needed In Quantum Mechanics? S o m e A n s w e r s Fo r T h e I n t r o d u c t o r y L e v e l . University Of Copenhagen, 2020, h t t p s : / / w w w. i n d . k u . d k / e n g l i s h / r e s e a r c h / didactics-of-physics/Karam_AJP_Complex_ numbers_in_QM.pdf. Tr e j o , M i g u e l . “ T h e M a t h B e h i n d S c h r ö d i n g e r E q u a t i o n : T h e Wa v e - P a r t i c l e Duality And The Heat Equation.”. Medium, 2020, https://towardsdatascience.com/themath-behind-schr%C3%B6dinger-equationthe-wave-particle-duality-and-the-heatequation-d5837bf4b13f.

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Game theory and how it aids our Helen Ng, Daniel Kan, world today Benjamin Law 1. INTRODUCTION John Nash (1928-2015) was a mathematician who made significant contributions to the fields of mathematics and economics and won a Nobel in Economics in 1994 and Abel Prize in Mathematics [1]. Nash has solved not only pure mathematics work like nonlinear partial differential equations but he has also introduced game theory which is extremely prominent in todayâ€™s business world. This essay will discuss how game theory can be applied to other aspects of society to aid sustainable development goals set by the UN. Specific examples include: 1) reducing income inequality and 2) improving the efficiency of travel networks. They reflect Sustainable Development Goals 10: reducing inequalities and 9: innovations, industry and infrastructure respectively [2]. Game theory is a process of analysing the strategic interaction between two or more players in a game, and it dictates how a player can best play a game. A game is defined as a set of circumstances that has a result dependent on the actions of the players - this can be nearly any situation involving two or more people. There are two types of game theories: competitive game theory and cooperative game theory. Competitive game theory is based on the assumption that the players would like to maximise their payoff, whether that be the most points, money or any other valuable rewards. On the other hand, cooperative game theory dictates that groups of players called coalitions will work together to reach a common goal.

Illustration by Tina Wu

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2.REDUCING PAY GAPS As of 2020, for every dollar a man makes, a woman makes an average of $0.81. Even the controlled pay gap, that is, when employing characteristic factors are “controlled”, dictates that for every dollar a man makes, a woman only makes $0.98. This puts a woman at an accumulated loss of $80,000 over her lifetime [3]. Therefore, in an ideal world of meritocracy, a person should be paid for the amount of work that they contribute to a team, such as a company, without taking into account factors like race, ethnicity, gender or sexuality. This falls in line with SDG Target 10.2 - “to empower and promote the social, economic and political inclusion of all, irrespective of age, sex, disability, race, ethnicity, origin, religion or economic or other status” and ultimately reducing inequalities. Putting this into the words of game theory, a player should receive their fair payoff of a value true to only the amount of contribution they give.

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2.1 Scenario Let a set of three workers N = {A, B, C} gain a net asset of 500 thousand dollars after completing a 50-page long business proposal, and the asset is to be divided up amongst the players. If each player works at a different rate, how should the money be distributed? If the players were to be working in different coalitions of all possible sizes (which means all subsets except for the empty set), let the table below be the mapping of a characteristic function v that links the powerset (2N = number of subsets for “N” given number of players; the proof uses binomial theorem) to the amount that they would write (could be any positive real number R+). Therefore, v := 2N → R+.

As stated in the table above, the total amount of pages (work) done by the three workers individually is not enough to pull together the proposal: the teamwork has brought extra magic to the coalition. Therefore, how should the asset be divided?

2.2 Shapley value using marginal contribution In a cooperative game, to determine what’s fair, a Shapley value is given to every player according to the contribution they bring to the team. The Shapley value is determined by taking the average of each player’s marginal contribution to other players in different permutations as represented by the table below.

The last row of Table 2.2 is the Shapley value(i) of each player; in other words, the contribution that they bring to the 50-page proposal. To find out the amount of money the workers should each receive, simply put into the equation:

Which yields 153 thousand for worker 1; 163 thousand for worker 2 and lastly 183 thousand for worker 3. In the process, only the amount of work done by each worker has been taken into consideration, thus ensuring equality for individuals no matter their personal backgrounds.

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3 . T R A F F I C N E T WO R K S Transportation is a crucial part of our societies: it covers everything that has to travel from one place to another, whether that be a person or valuable goods. However, more often than not, these trips are time-sensitive and increasing travel time would mean that less profit can be made, ultimately impacting the economy. SDG Target 9.1 also states “developing quality, reliable, sustainable and resilient infrastructure, including regional and transborder infrastructure” is needed “to support economic development and human well-being”. Therefore, a smooth traffic network is essential to ensure the proper functioning of all industries and to underpin the development of a country. A traffic network is a structure which involves players driving along routes. This could simply be a highway, power lines, air routes, or even an online network sending packets of data from one point to another. Within the network, each player aims to strategically choose their route to minimise travel time and avoid congestion.

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Let there be two points, A and B, and each player aims to go from A to B within the least amount of time - which means taking the route with the least congestion. Assume that cars come out of A at a constant rate, and also leave immediately once they reach B. The â€œspeedâ€? of the car is defined as the number of patches it moves across in one tick, in other words, the distance it travels over 1 unit of time.

The two routes AC and DB are more sensitive to congestion because the speed of a car travelling across it is the number of total cars divided by the number of cars going that route then divided by 10. For example, if there were 100 cars in total and 20 cars went through AC, the speed will be 0.5. The speed of a car going through CB or AD would be the same: both are one patch per tick. The simulation below models the situation when 500 cars all decide to travel from A to B via C. It would take 8324 ticks for all the cars to complete their journey.

The table above shows that if exactly half the cars take the upper route and lower route respectively, all the cars can travel from A to B within the shortest time. This is the Nash Equilibrium. This is because if the drivers were split evenly between the two routes, none of them would have the incentive to switch from one route to the other, as that would increase the time taken. Therefore, if we test the simulation again with 225 taking route AC and 275 taking route AD, the result would be 7758 ticks. The cars will take longer to finish compared to the Nash equilibrium.

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3 . 2 B r a e s s ’s Pa r a d o x In the previous example, the equilibrium was found very easily. However, if we introduce an extra route CD, counterintuitively, it will increase the time it takes for all the cars even if the time it takes to cross this new highway is defined as zero because the new Nash equilibrium dictates that all the cars would go from A to C to D then to B. This is the only equilibrium because only then, no driver would benefit by switching lanes. If we run the simulation, this remains true. The extra lane does not improve the traffic; instead, the congestion is now worsened.

Therefore we can conclude that adding extra lanes doesn’t necessarily benefit traffic, but can often even make it worse. In this model, cars can directly “teleport” from C to D, but in real life it would take much longer, meaning if it did take time to go from C to D, the congestion would well be even worse. This implies that building new roads should always be considered with care since they do not necessarily improve traffic.

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4. CONCLUSION Above were just two examples of how game theory can be applied to better our society. The applications of game theory extend long beyond the gender pay gap and traffic network models above; however, within the time allowed, these were the two models chosen by us to best represent the diversity of game theory applications. Furthermore, the two models have been greatly simplified compared to a real-life situation. For example, Section 2 mentions giving salary according to work done, but in a running company, if a worker is on sick leave or maternity/paternity leave, there should be compensations for the worker even if she/he is unable to work. Section 3 discusses a traffic network that takes cars from one point to another; however, a highway in real life would have more entries and exits, posing significantly greater complications. Further research and modelling could be conducted to best simulate a realistic scenario that takes into account factors including but not limited to the ones suggested above.

Bibliog raphy [ 1 ] G o o d e , E r i c a . “ J o h n F. N a s h J r. , M a t h G e n i u s D e f i n e d b y a ‘ B e a u t i f u l M i n d , ’ D i e s a t 8 6 . ” T h e N e w Yo r k T i m e s , T h e N e w Yo r k T i m e s , 2 4 M a y 2 0 1 5 , w w w. n y t i m e s . c o m / 2 0 1 5 / 0 5 / 2 5 / s c i e n c e / j o h n nash-a-beautiful-mind-subject-and-nobel-winner-dies-at-86.html [2] United Nations. “THE 17 GOALS | De partment of Economic and Social Affairs.” United Nations, United Nations, 2015, sdgs.un.org/ goals. [3] Payscale. “Gender Pay Gap Statistics for 2020.” PayScale, 2020, w w w. p a y s c a l e . c o m / d a t a / g e n d e r - p a y - g a p .

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John Nash and his co Introduction He was a quirky professor at Princeton University whose students described him as a â€˜world-class trollâ€™. He was an adamant classical music lover who could whistle an entire music piece in elementary school. However, most importantly, he was one of the most beautiful mathematical minds of all time. This man was none other than John Forbes Nash Jr., an American mathematician whose work had significant impacts on various fields including economics, geometry, and social sciences. He is most known for his Nash Equilibrium, our primary focus in this essay. It was a gamechanger for game theorists, and gave insight into the complex process of decision making that applies to almost every academic field and helps explain common phenomena in our daily lives.

An interview with John Nash. Source: pbs.org

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n tributions to SDGs

Kevin Liew, Chloe Levieux and Andrew Wang In the 1950s, an American non-profit global policy think tank, RAND Corporation, led investigations into game theory for its potential usage in global nuclear strategies. During this time, the organisation published papers written by John Nash in which he outlined the Nash equilibrium. A Nash equilibrium is the stable state of a system where, for a certain amount of people, no one can change their strategy to gain a more desirable outcome as long as the other n-participants’ plans do not change. The theory provided a way of predicting the possible outcome of a game with n-players in which each acted to maximise self-interest. To fully understand the extent of this theory’s significance, we must establish the definitions of critical key terms. A strategy takes into consideration all combinations for every possible situation of a game, allowing one participant to make a move that can maximise the benefits they receive from it. Nash established that pure strategy dictates the actions a player will make in any given situation, whilst mixed methods (of which there is an infinite amount) assign as n-probability to each pure strategy to allow n-players to pick them randomly. A non-zero sum game refers to a situation where one person’s gain or loss may not necessarily affect another person’s failure or success. In other words, n-players’ interests are not directly opposed, so the wins and losses in a game do not necessarily balance each other out to zero, and there is a possibility of mutual gain in a win-win situation. So, Nash proved that for a finite n number of players in a non-zero-sum non-cooperative game, there exists a Nash equilibrium in mixed strategies. Assuming your superior intellect allows you to understand the term ‘non-cooperative’, we will move on to explore the infamous example of the Prisoner’s Dilemma to further cement this concept.

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P r i s o n e r ’s D i l e m m a First, let us explain the Prisoner’s Dilemma. This problem was initially proposed back in 1950 by Merrill Flood and Melvin Dresher, two American mathematicians working at RAND Corporation. The Prisoner’s Dilemma analysed, as part of RAND’s research into game theory, why two entirely rational individuals might choose not to cooperate, even if they could gain a better outcome for themselves by working together. There are many interpretations and variants of the Prisoner’s Dilemma. However, for the sake of consistency, we will be using the following scenario: two members of a crime syndicate have been caught by the police and taken in for questioning. The two criminals have no means to communicate with each other once arrested. The District Attorney lacks enough evidence to associate them on the principal charge, but they have enough to convict both prisoners on a lesser crime. The District Attorney gives the two prisoners the same offer separately; they can either confess that the other prisoner committed the crime, or they can remain silent and cooperate with the other prisoner. This proposal can lead to 1 of 4 outcomes. If prisoner A confesses and prisoner B does not, prisoner A’s sentence will be lowered down to 1 year, whereas prisoner B will serve 10 years. If prisoner B confesses and prisoner A does not, the reverse happens. Both prisoners staying silent leads to both serving 2 years. Both prisoners admitting their guilt results in them serving 3 years. Just for simplicity, we will ignore the limitations of this Nash equilibrium – these outcomes do

not affect either prisoner’s reputation within the crime syndicate, and they will not get retribution or payback on each other. No external factors influence their decision. From the perspective of prisoner A, if prisoner B were to confess, his best option would be to do the same and only receive 3 years of imprisonment instead of 10. Alternatively, if prisoner B did not disclose information, it would also be in prisoner A’s best interest to confess to only serve 1 year in prison instead of 3. This is because if prisoner A also decided to stay silent, he would run the risk of getting 10 years in jail if prisoner B changed his mind and decided to confess. Both prisoners are likely to have this thought process, and so this would most likely lead to the result where both receive 3 years in jail. This outcome is the only one with a Nash equilibrium as no prisoner can change their strategies to gain a lighter sentence if the other prisoner’s choice to confess remains constant. As such, we can conclude that the most optimal outcome for both prisoners collectively would be to stay silent. However, this is not feasible as the possibility of the other individual betraying the prisoner for their gain is more than likely enough to sway their opinion into confessing. This example relates to the real world where due to several participants or parties only seeking to benefit themselves, the situation does not result in the optimal outcome for all parties and thus ends in a Nash equilibrium where everyone suffers more.

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1. Regulations of CO2 emissions

As we have covered the basics of the Nash Equilibrium, we will move on to one of the most paramount applications of the Nash Equilibrium – the regulation of CO 2 emissions. Climate change and global warming are substantial global concerns, but as each country individually has an economic interest in emitting CO 2 for their industrial production, global inaction occurs. This refusal to make personal sacrifices for the collective greater good is a Nash equilibrium. All countries produce CO 2 to create cheap energy. Hence, there is less impetus to deviate from their original energy plans. Countries may also be tempted by free-riding off of other nations’ climate action, which can offer the prospects of benefits of policy action without the costs of abatement, creating a second Nash equilibrium. The Nash Equilibrium can also explain how every individual following their optimal course of action does not yield the best outcome for the group. Therefore, we need intervention if we wish to reach the desired outcome for everybody, namely via the use of treaties or legally binding documents, such as the Paris Agreement, to enforce and impose guidelines. However, Nash’s theory does not account for the consequences of irrational behaviour; history has shown that humans are not rational beings. On June 1, 2019, US President Donald Trump announced that the U.S. would withdraw from the 2015 Paris Agreement on climate change mitigation, stating that it ‘will undermine [the U.S.] economy’ and ‘puts [the U.S.] at a permanent disadvantage’. President Donald Trump chose to free-ride off of the climate action of other nations and avoid the burden of carbon abatement costs, ignoring the Nash equilibrium.

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FEATURED ARTICLES Providing an insight into climate change scenarios, the Nash Equilibrium helps to target the UN’s social development goals, one being climate action. Target 13.2 involves integrating climate change measures into national policies. John Nash’s work also directly targets Partnership, the 17th SDG, by helping countries cooperate and abide by a particular set of guidelines to achieve sustainability. For example, the Nash Equilibrium could convince governments to work together towards Life Below Water, the 14th SDG, by lessening the effect of global warming to keep sea temperatures from rising. They could also implement specific policies to protect the incomparable biodiversity of the aquatic world. Hear it from Nash himself: “The best for the group comes when everyone in the group does what’s best for himself and the group.”

Paris agreement signature ceremony. Source: Flickr

2. Applications in sports

In sports scenarios, the use of illegal performanceenhancing drugs can cause a significant disadvantage towards rule-abiding players. The Nash Equilibrium, just like in the CO 2 emissions example, provides an insight into the case by emphasising the importance of intervention, like mandatory blood content checks and a penalty for violation of fair play. The Nash Equilibrium can be applied to almost every competitive event like this and dramatically helps sustainable development goal 16 – Peace, Justice, and Strong Institutions – by promoting an international institution of fair play (16.6) and a law regulating sports events. (16.3)

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N a s h ’s p e rs o n a l e x p e r i e n c e s and mental illness Nash suffered and then recovered from schizophrenia, a severe mental disorder in which people interpret reality abnormally. The Swedish Academy of Sciences almost denied him his Nobel prize for his work in economics as members felt that esteeming a ‘madman’ would damage the Nobel brand’s image and ruin the prize ceremony. However, the prize committee recognised that mental illnesses were, after all, valid medical conditions, just like other conditions such as heart disease. Nash’s recognition as a mathematician secured his prize, regardless of his schizophrenic condition. Winning the Nobel prize, one of the highest honours that a mathematician can get, broke the negative stigma regarding the mentally ill. SDG 3.4 aims to ‘promote mental health and well-being’, and SDG 16.6 seeks to ‘promote and enforce non-discriminatory laws and policies for sustainable development’. With his success, Nash created awareness for both goals, revealing how the ignorant discriminatory behaviour towards people suffering from mental health issues prevented the acknowledgement of their impactful achievements. Policies must be put in place to create a more inclusive, accepting, and sustainable society where everyone excels and thrives. Shattering the public’s prejudice, Nash’s accomplishments send a powerful message that mental illnesses should not deprive one’s standing in a sustainable society, and that we should recognise people for who they are, and not whether they conform to any ideal.

John Nash at the Nobel prize ceremony. Source: American Experience, PBS

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Conclusion There you have it – John Forbes Nash Junior. Generations will remember one of the most brilliant mathematical masterminds, whose Nash Equilibrium provides an acute insight into the consequential governmental decisions that dictate the sustainability of our future, as well as the complex mechanisms that operate in our daily lives. So, the next time you and your friend find yourself participating in a failed bank heist, or signing on the most recent global climate change agreement, think back to John Nash and his explorations on the consequences of selfishness. In the long run, a collectivist approach is a much better approach than self-centred desires: as Josh Nash said, “Perhaps it is good to have a beautiful mind, but an even greater gift is to discover a beautiful heart!”

Bibliog raphy Cazals, Charles. “How Game Theory A f f e c t s Yo u r E v e r y d a y L i f e ” . h t t p : / / w w w. t h e l o n d o n g l o b a l i s t . O r g / , 2 0 2 0 , h t t p : / / w w w. t h e l o n d o n g l o b a l i s t . org/how-game-theory-af fects-youreveryday-life/. Yu r c a b a , Jo . “A s A P r o f e s s o r, Jo h n N a s h Wa s To u g h , Q u i r k y, A n d H i l a r i o u s , A c c o r d i n g To H i s Fo r m e r Students”. Bustle, 2020, https:// w w w. b u s t l e . c o m / a r t i c l e s / 8 5 5 2 0 - a s a-professor-john-nash-was-toughquirky-and-hilarious-according-tohis-for mer-students. Khan, Sal. “More On Nash E q u i l i b r i u m ( Vi d e o ) | K h a n A c a d e m y ” . K h a n A c a d e m y, 2 0 2 0 , h t t p s : / / w w w. k h a n a c a d e m y. o r g / economics-finance-domain/ ap-microeconomics/imperfectcompetition/oligopoly-and-gametheory/v/more-on-nash-equilibrium.

“ G a m e T h e o r y ” . E n . Wi k i p e d i a . O r g, 2020, https://en.wikipedia.org/wiki/ G a m e _ t h e o r y. A c c e s s e d 1 6 N o v 2 0 2 0 . “Strategy (Game Theory)”. E n . Wi k i p e d i a . O r g, 2 0 2 0 , h t t p s : / / en.wikipedia.org/wiki/Strategy_ (g ame_theor y). Accessed 16 Nov 2020. “A ‘ B e a u t i f u l M i n d ’ a n d h i s N o b e l P r i z e ” . C h r i s t i e ’s , 2 0 2 0 , h t t p s : / / w w w. christies.com/features/A-BeautifulM i n d - Jo h n -Nash-and-the-Nobel-Prize-10124-7. aspx. Accessed 16 Nov 2020. G o o d e , E r i c a . “ Jo h n F. N a s h J r. , M a t h Genius Defined by a ‘Beautiful Mind,’ D i e s a t 8 6 ” . T h e N e w Yo r k T i m e s , 2020, h t t p s : / / w w w. n y t i m e s . com/2015/05/25/science/john-nasha-beautiful-mind-subject-and-nobelwinner-dies-at-86.html.

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