THE
UNIVERSE
AS IT REALLY IS Earth, Space, Matter, and Time
T h o m a s R. S c o t t with the assistance of J a m e s Lawrence P o w e l l
Introduction
W
ell, here we are—and there wasn’t much chance of that. For several billion years, all sorts of things had to happen just so for me to be tapping on a keyboard in a moment we arbitrarily label 2017. The very fabric of the cosmos—nature’s fundamental forces, the mass of the proton, the age of the universe itself—had to align precisely to create the universe that created us. Physics permits biology. That permission set us on a winding evolutionary path guided by drastic climate changes, fuming volcanoes, sliding tectonic plates, and the occasional bull’s-eye by a suicidal asteroid—a four-billion-year odyssey never to be repeated and the only possible story that could have led to human life. Having permitted biology, physics dictates its fate. Even after this unlikely sequence, our existence as individuals would have been a fool’s bet as Homo differentiated itself from the great apes. Through 125,000 generations, that little sperm had to beat 100,000,000 rivals to that big egg every time to make you. Your chances of hitting the lottery are greater than your chances of being here to buy the ticket. A miracle? Perhaps an overarching intelligence preordained human existence and set the proper context. Science is silent on this possibility because there is no way of discovering such an intelligence—but the probability it exists is low. Rather, we are more likely to be here just because the last 13.7 billion years unfolded as they did. Had the universe not been as it really is, there would be no one to wonder at its existence. Realms beyond our universe may offer a different physics from the one we see around us,
2 ˙ Introduction
but they would go unbeheld by conscious life-forms. We will never know a universe other than our own; our laws of physics prevent it. So the issue of whether our universe is only one among a multiverse of options that permitted our existence or the one and only will remain primarily in the domain of philosophy and statistical probabilities, and any discussion of these possibilities must rest elsewhere on your bookshelves. In this book, we’ll explore what we do know—what we can see, measure, and deduce from those measurements. Earth and the physical features familiar to us will occupy most of our tour, but we will finally escape to the planets, stars, and the more extraordinary members of the cosmos. In our first five chapters, we’ll visit physics (the fundamental science) and chemistry (the central science). Physics is mathematical and lawful, providing the rules that all other areas of science must obey. It concerns the very properties that govern our universe: time, light, motion, force, temperature, and charge, among other things. Physics is all-encompassing, from quarks to quasars. Indeed, the two defining theories of the twentieth century—quantum mechanics and relativity—capture these extremes. Until Max Planck and Albert Einstein each imposed their respective creative genius, we did not think small enough to imagine the subatomic world of quantum mechanics or large enough to embrace the heroic masses and speeds that revealed relativistic properties at a cosmic level. Physics, and its practice through engineering, dominated the twentieth century, from the Panama Canal in its second decade, through the Manhattan Project in its fifth, the space program in its seventh, the Global Positioning System in its ninth, and the continuing revolution in communications. With the rise of molecular biology, the emphasis in American science has shifted from the physical to the life sciences and the promise of a revolution in the practice of medicine. Yet physics still dictates the conditions for life; biology adapts or perishes. Physics is the hardware and biology the software. Chemistry is the sprawling discipline that bridges the physical and life sciences, bordering on physics (physical chemistry) at one edge and biology (biochemistry) at the other. The molecules with which it deals can be as simple as a pair of hydrogen atoms or as complex as the hundreds of billions of atoms that compose a molecule of human DNA. It’s a recent science, depending as it does on an understanding of the interactions among
Introduction h 3
atoms. Through the nineteenth century, scientists debated the very existence of atoms, delaying understanding of their interplay. John Dalton’s laws of definite and multiple proportions (1803–1808)1 convinced most scientists that atoms combined to form molecules, but prominent physicists were unconvinced. Not until scientists discovered electrons, protons, and, finally, neutrons was the atom established as a physical reality. Then the experiments of Jean Perrin on Brownian motion of minute particles in suspension (1911) demonstrated the existence of molecules (and earned Perrin the Nobel Prize in Physics in 1926). At last scientists could begin to comprehend the interplay among electrons in the outer atomic shell, which determined how atoms joined to make molecules. Functional chemistry may have been practiced in kitchens, apothecaries, and forges for millennia, but an understanding of the principles that underlie that chemistry is little more than a century old. There are more chemists at work today in the United States than there are astronomers, physicists, geologists, or mathematicians. The American Chemical Society has more members than the societies of these other four sciences combined.2 Chemistry is a rich, diverse, active field whose outcomes have shaped nearly every aspect of modern society. With the basic principles in hand, we’ll tour the Earth in the middle chapters, discovering how it came to be the welcoming planet that sustains us and what lies beneath its surface. Then we’ll explore the two fluids—air and water—that permit and define our lives. The earth sciences are the most integrative of the disciplines we’ll visit. Knowledge springs from geophysics and geochemistry and more recently from geographic information systems, which have revolutionized our understanding of Earth’s surface. That understanding has never been more critical than in this era when we threaten the land, seas, and air through human activity. Geography is to space what history is to time,3 as we’ll come to appreciate in chapters 6 through 9. Our tour will take off for the planets and stars in the final chapters. Astronomy captures the imagination like no other science. It is whimsical in its constellations, is informative in its application to navigation, offers portent through astrology, and is rigorous in its physics. Astronomy enchants the amateur, inspires the lover, and challenges the professional. I have a friend who, if he wants to converse with the person seated next
4 ˙ Introduction
to him on a plane, says he’s an astronomer; if he wants solitude, he says he’s an astrophysicist. Astronomy can be engaging or perplexing. It has engendered the most outrageous theories and has seen them turn out not only to be true but also to have been necessary for our own existence. There are those who do not like mathematics, chemistry, or physics. But who does not like astronomy? The notion for this project originated with a brief weekly report called Skytalk, which airs on WHYY, Philadelphia’s National Public Radio (NPR) station. I tuned in from my home in northern Delaware in the 1990s. When I moved to San Diego State University (SDSU) to serve as dean of sciences, I was delighted to discover that my new institution owned the local NPR station, KPBS. This, I thought, was the perfect forum for bringing science to the public and for promoting SDSU, which shares the academic landscape with the imposing University of California, San Diego, across town. I approached KPBS’s General Manager Doug Myrland and Program Director John Dekker with the proposal for a weekly broadcast titled San Diego Science. They graciously accepted, and for the next five years, I composed commentaries on all manner of scientific topics for an audience of about 20,000. These broadcasts were embedded in Science Friday, a segment of NPR’s Talk of the Nation. When KPBS decided not to renew Talk of the Nation, the context for San Diego Science was lost, and the project came to an end. My primary reaction at the time was relief, for preparing the piece by the Wednesday deadline each week brought unwelcome pressure to an already overburdened schedule. Now freed from daily academic obligations, I return to the wealth of information my advisory committee members and I accumulated to refresh, embellish, integrate, and reorganize it into a coherent tour of the physical sciences. There is a need for such a tour. The video A Private Universe shows the responses of Harvard graduates at their commencement when asked what causes Earth’s seasons. Many responded with the self-assurance of the leaders they’re destined to become that the Earth moves in an oval around the Sun; sometimes it is closer (summer) and sometimes farther (winter).4 The interrogator failed to ask the question
Introduction h 5
that would have belied that answer: When it’s summer in Cambridge, what season is it in Melbourne? As an alumnus of Princeton University, I was confident that this misguided hubris was attributable to Harvard’s lax admission standards. However, it turns out that graduates of other expensive institutions were equally naïve about this fundamental rhythm of our lives. Our tour will correct such misimpressions. It is intended for the same people who tune in to NPR: thoughtful, curious nonexperts. It is less detailed and demanding than most textbooks, but it offers greater substance and context than the typical media report. Interspersed with the science, you will find history and biography. I have traced the historical roots of most topics and offer brief biographies of the main characters. Many arcane scientific terms come alive when set in their historical context, and I offer those etymologies when possible. Science often blends into technology, as we’ll explore lasers, LEDs, cameras, and the Global Positioning System. The occasional simple experiment will tell you how to engage school-age children to measure the speed of light, calculate the amount of oxygen in the air, demonstrate hydrogen bonding, desalinate water, and calculate the day of the week for any date in the past or future. Throughout, I’ve tried to answer questions I’ve wondered about at some point myself. What would a journey to the center of the Sun be like? The Sun exerts more gravity on Earth than the Moon, so why does the Moon control Earth’s tides? Why are the inner planets small and rocky and the outer ones large and gaseous? What’s the difference between a pulsar and a quasar? What gives gold its yellow luster? Why are some elements radioactive and others magnetic? Why is cold water richer in nutrients than warm water? Why do high-pressure weather systems rotate clockwise and low-pressure weather systems rotate counterclockwise in the Northern Hemisphere? How many stars are there? Where are they made? Come along. Let’s get started.
The Universe as It Really Is
h Michael Man n ,
Distinguished Professor, Penn State University, and coauthor of The Madhouse Effect: How Climate Change Denial Is Threatening the Planet, Destroying Our Politics, and Driving Us Crazy Thomas R. Scott (1944–2017) was pro-
fessor emeritus of psychology and academic vice president emeritus at San Diego State University, where he also served as dean of the College of Sciences, vice president for research, dean of the Graduate Division, and chief executive officer of the SDSU Research Foundation. James Lawrence Powell is execu-
author of The Traveler’s Guide to Space: For OneWay Settlers and Round-Trip Tourists h N eil F. Co min s ,
“A delightful, well-written tour of the universe. Scott covers a lot, from seafloor spreading to supernovas twinkling brightly in the sky. Now more than ever, we need citizens to stand up for sound science, not some convenient ideological take on it. The Universe as It Really Is tells readers how the real universe works and how we know it. What a pleasure it is to recommend this book!” h Harry Shipman , Annie Jump Cannon Professor Emeritus, Univer
sity of Delaware
ISBN: 978-0-231-18494-6
Jacket design: Lisa Hamm Jacket image: © ArSciMed/Science Source Printed in the U.S.A.
T
he universe that science reveals to us can seem far outside the comfort zone of the human mind. Subjects near and far open up dizzying vistas, from the infinitesimal to the colossal. Humanity, the unlikely product of uncountable coincidences on unimaginable scales, inhabits a tumultuous universe that extends from our immediate environs to the most distant galaxies and beyond. But when the mind balks at the vertiginous complexity of the universe, science unveils the elegance amid the chaos.
THE
UNIVERSE
AS IT REALLY IS Earth, Space, Matter, and Time
columbia university press / new york cup.columbia.edu
columbia
tive director of the National Physical Science Consortium. He previously served on the National Science Board and has also been president of Franklin and Marshall College, Reed College, the Franklin Institute Science Museum in Philadelphia, and the Los Angeles County Museum of Natural History. Powell is the author of The Inquisition of Climate Science (2011) and Four Revolutions in the Earth Sciences: From Heresy to Truth (2014), both from Columbia University Press.
“The Universe as It Really Is offers an excellent vision of the natural history of the cosmos. With the impressive breadth of topics, the reader gains a clear sense of the ‘big picture’ of the natural world.”
THE universe AS IT REALLY IS
“Evocative of Sagan’s The Demon-Haunted World, Thomas R. Scott’s book is a breezy yet comprehensive and authoritative treatise on the science underlying our universe, our world, and our place in it.”
scott
PRAISE FOR
T h o m a s R. S c o t t with the assistance of J a m e s Lawrence P o w e l l
In this book, Thomas R. Scott ventures into the known and the unknown to explain our universe and the laws that govern it. The Universe as It Really Is begins with physics and the building blocks of the universe— time, gravity, light, and elementary particles—and chemistry’s ability to explain the interactions among them. Scott, with the assistance of James Lawrence Powell, next tours the earth and atmospheric sciences to explain the forces that shape our planet and then takes off for the stars to describe our place in the cosmos. He provides vivid introductions to our collective scientific inheritance, narrating discoveries such as the shape of the atom and the nature of the nucleus or how we use GPS to measure time and what that has to do with relativity. A clear demonstration of the power of scientific reasoning to bring the incomprehensible within our grasp, The Universe as It Really Is gives an engrossing account of just how much we do understand about the world around us.