Paul Davies - Whats Eating the Universe?: And Other Cosmic Questions

PENGUIN BOOKS

UK | USA | Canada | Ireland | Australia
New Zealand | India | South Africa

Penguin Books is part of the Penguin Random House group of companies whose addresses can be found at global.penguinrandomhouse.com.

First published by Allen Lane in 2021

Copyright Paul Davies, 2021

The moral right of the author has been asserted

The author and publishers are grateful to the following for permission to reproduce images: Figures copyright Westminster Abbey.

Cover photograph Getty Images

ISBN: 978-0-141-99373-7

This ebook is copyright material and must not be copied, reproduced, transferred, distributed, leased, licensed or publicly performed or used in any way except as specifically permitted in writing by the publishers, as allowed under the terms and conditions under which it was purchased or as strictly permitted by applicable copyright law. Any unauthorized distribution or use of this text may be a direct infringement of the authors and publishers rights and those responsible may be liable in law accordingly.

Whats Eating the Universe? is a scientific detective story. It explains how age-old cosmic puzzles have recently been solved, while startling new discoveries are upending our understanding of physical reality. To fully grasp the big picture, we must take a journey from the very edge of time itself, through our own epoch, into the infinite future. This is cosmology, the study of the origin, evolution and fate of the entire universe. It weaves together the large and the small, the vastness of space with the innermost recesses of subatomic matter a human endeavour of breathtaking audacity, tackling fields of inquiry that for millennia lay exclusively in the provinces of religion and philosophy.

There may be those who feel that, when the bright light of scientific inquiry is shone into the hidden workings of nature, it strips away the romance of the unknown. I have always believed, however, that the deeper we probe, the more beautiful and awe-inspiring the physical world appears. Nature demystified is nature revealed in all its glorious subtlety and elegance. It is good that we should know. In the chapters that follow, we will explore humankinds cosmological discoveries in detail, and examine the fundamental philosophical questions that flow from them questions such as why the universe exists at all, why it has the form it does, why the laws of nature are as they are, and how a system of mindless, purposeless particles brought forth conscious, thinking beings who can make some sort of sense of their world.

I have been preoccupied by these big questions of existence all my life, and I am privileged to have been able to work on some of them professionally in my career as a theoretical physicist, cosmologist and astrobiologist. While my own contributions have been modest, I have rubbed shoulders with some of the giants of physics and astronomy, women and men of sparkling intellect and insatiable curiosity, whose infectious zeal for understanding the world from the perspective of science has been a constant source of inspiration. I have lived through one of the most exciting times in the entire scientific enterprise, when many big questions were transformed from dreamy theorizing to hard-won discovery. As so often in science, one question was answered only to raise a dozen others. And so it is today. Much has been achieved but much remains shrouded in mystery. I conceived of this book as a concise summary of our current state of understanding.

So many people have helped me with my research over the years that they are too numerous to list here, but I should like to acknowledge Cecilia Lunardini and Rich Lebed of Arizona State University, who clarified some aspects of particle physics for me, Charley Lineweaver of the Australian National University for his assistance with the characteristics of cosmological horizons, Glenn Starkman for his inspirational lecture about the oddities in the cosmic microwave background radiation, and Simon Mitton for drawing my attention to some historical inaccuracies. Lucy Hawking and Christopher McKay provided valuable help with the figures. Special thanks must go to my wife, Pauline, for her encouragement and critical reading of the text. Her communication skills far exceed mine, and much of the credit for the end product must go to her editorial refinements. Finally, I should like to thank my editor at Penguin, Chloe Currens, for her suggestions, comments and guidance, delivered in an unfailingly cheerful tone.

Paul Davies
Phoenix, March 2021

On 14 January 1990, the worlds press featured a mottled red-and-blue image purporting to show nothing less than the birth of the universe. It was like looking at the face of God, proclaimed the projects lead scientist, George Smoot. In the words of Stephen Hawking, the picture represented one of the greatest scientific discoveries of the century, if not all time.

The subject of these superlatives was a colour-coded heat map of the sky produced by a satellite called COBE, for Cosmic Background Explorer. COBE had been tasked with surveying the fading afterglow of the Big Bang, a sea of microwaves that suffuses space and travels to us largely undisturbed from a time when the cosmos was a tiny fraction of its current age. The amorphous-looking splodges decorating the image indicated slightly hotter and cooler regions of the universe. Etched into this kaleidoscopic pattern were important clues about the birth pangs of the cosmos a split-second after its origin, at the very edge of time itself.

COBE ushered in a golden age of cosmology. In the three decades since, the field has been transformed from a speculative backwater to a precision science. Paradoxically, we now understand the history of the universe in its overall outline better than we understand the history of our own planet. Yet, to borrow from Churchill, this is not the end of cosmology. It is not even the beginning of the end. But it is, perhaps, the end of the beginning.

Cosmology might seem like a rarefied discipline, but in many indirect ways it touches everyone. We all have a need to know why the world is as it is and how we came to exist. Throughout history, societies have sought to address this need by producing creation myths: accounts which werent explanations in the scientific sense but stories intended to place human beings in the context of a grander scheme. When cosmology emerged as a scholarly discipline among the ancient Greek philosophers two and a half millennia ago, it was given a name that derived from the same root as cosmetic, meaning beautiful, whole and complete; standing in opposition to chaos. The word implied that there was such a thing as a universe, a coherent and organized entity that can be understood by human reason. Further progress, however, had to await the scientific age two thousand years later, which unleashed a stream of dazzling discoveries. When in 1543 Copernicus declared the Earth goes around the sun, he shattered the anthropocentric model of the cosmos that had prevailed for centuries. To be sure, the immediate effect on daily life was minor; there were no riots, no wars, no economic disruptions. Yet, over time, the knowledge that we are not located at the centre of the universe fundamentally transformed the context of all human existence. The impact was felt not only in science, but in religion, sociology and economics too.