The Pantomath
Figure 1: Example of a spiral galaxy. Andromeda is our twin galaxy and we can see it fully (we cannot see the Milky Way in the same way just because we are inside it).
The Equation of the Universe in the life of an overthinker Giorgio Manzoni
Since the beginning of humankind, people have been wondering about the Universe. Acknowledging the fact that we will probably never know the reason why there is a Universe and why it is like this, scientists started to apply their hard math to model it. The equation of the Universe is one of the biggest achievements in that direction but it might sound a bit intimidating. Is it actually possible to describe the entire Universe with just an equation? What does it mean to describe the Universe? Moreover, is the community of scientists reliable? I am Giorgio, I’m a PhD in astrophysics, but my primary school teacher used to call me “Valentino”. It’s an Italian name but if you split it into two parts it becomes “va-lentino”, which means, with a little bit of imagination, “someone who goes slowly”. With probably all of the best intentions, she thought that humiliating me in front of my classmates would have stimulated me to be faster and at the pace of the other “average-speed” kids. I have never changed. I found myself many times wondering about things that everybody around me would have accepted as they were, without wasting additional time. Curiosity can be demanding in terms of time and not everybody would consider it well spent. After high school, this sense of curiosity pushed me to enrol into the Physics degree. I was uncertain as I have always been fascinated by Philosophy or Psychology and that would have been an easier choice given my natural skills. Having finished my bachelor, I completed a Master’s in Astrophysics and here I am now in Durham for my PhD. After a while in this field, I can tell you, my dear overthinker friend, that, even if not immediately appreciated, overthinking about the Universe is always worth it. The reason is the following. Sometimes we like to take things for granted because it helps us to make faster decisions and free up space in our brain. However, this page 16
is a very dangerous process when you are dealing with a Universe consisting of material where 70% is as yet unidentified. Scientists decided to call it Dark Energy, exactly because the origin is completely obscure. However I can tell you that overthinking about it, is not just a good idea but it’s something necessary if we want to progress in science.
I found myself many times wondering about things that everybody around me would have accepted as they were... When studying cosmology I became suddenly fascinated about how we can describe the Universe in a simple threeingredients cooking recipe. Wait, you are not surprised enough: I am saying that if you have these three things, you can create the Universe you live in! These ingredients are: matter (Ωmat,0about 30%), light (Ωrad,0about 0.008%) and dark energy (Ωʌabout 70%). Unfortunately, not particularly easy to find at the local market… To complicate things a bit, that 30% of matter is not completely under
control as only 4% of it is composed by matter we know, called by astrophysicists baryonic matter, and the remaining 26% is named dark matter. Yes, do not let the confusion come into your mind, you read it right. Dark matter is not dark energy, and, in our Universe, there is no real reason for treating dark matter differently from baryonic matter. You might have guessed at this point that when things become “dark”, it means that they are not completely understood. True. However, while dark energy is probably one of the biggest enigmas in astrophysics, we can “see” dark matter quite well through the eyes of gravity. Take the example of a spiral galaxy (Figure 1), like our wonderful Milky Way, the galaxy we live in. With our telescopes, we can see very well that the stars in this kind of galaxy rotate around the centre of the galaxy. Furthermore, we can measure the rotational velocity of these stars! For example, on average, stars in the Milky Way rotate at 220 kilometres per second (pretty fast, isn’t it? How many kilometres can you run in one second?). Assuming we have understood gravity pretty well, it is impossible to reproduce the rotation of galaxies without taking into consideration the contribution of additional matter, which unfortunately cannot be seen with any telescope. Although the concept of invisible matter might not sound very scientific, it actually is because the reason
