A Brief History of the Universe Read online

  J.P. McEvoy was awarded an Msc in physics from the University of Pennsylvania and a PhD from the University of London. As a research associate at the RCA Research Laboratories in Princeton and for the next 15 years, he worked in solid state physics as a research scientist in the US, Switzerland and the UK. His two previous books, Introducing Stephen Hawking and Introducing Quantum Theory have been acclaimed worldwide and translated into a dozen languages. He has also written a popular book on the history of solar eclipses for Fourth Estate. Recently, he has been active in science journalism and broadcasting. [email protected].

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  A BRIEF HISTORY OF

  THE UNIVERSE

  J.P. McEVOY

  Constable & Robinson Ltd

  3 The Lanchesters

  162 Fulham Palace Road

  London W6 9ER

  www.constablerobinson.com

  First published in the UK by Robinson,

  an imprint of Constable & Robinson, 2010

  Copyright © J.P. McEvoy, 2010

  The right of J.P. McEvoy to be identified as the author of this work has been asserted by him in accordance with the Copyright, Designs and Patents Act 1988

  All rights reserved. This book is sold subject to the condition that it shall not, by way of trade or otherwise, be lent, re-sold, hired out or otherwise circulated in any form of binding or cover other than that in which it is published and without a similar condition including this condition being imposed on the subsequent purchaser. A copy of the British Library Cataloguing in Publication Data is available from the British Library

  UK ISBN 978-1-84529-684-1

  1 3 5 7 9 10 8 6 4 2

  First published in the United States in 2010

  By Running Press Book Publishers

  All rights reserved under the Pan-American and International Copyright Conventions

  This book may not be reproduced in whole or in part, in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system now known or hereafter invented, without written permission from the publishers.

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  Digit on the right indicates the number of this printing

  US Library of Congress Control Number: 2008931539

  US ISBN 978-0-7624-3622-4

  Running Press Book Publishers

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  Printed and bound in the EU

  The author dedicates this book to the genius and compassion of Johannes Kepler, the world’s first astrophysicist, and Albert Einstein, the world’s first theoretical cosmologist . . .

  And to my four grandchildren: Emily, Muirenn, Joel and Leelah who have promised me that they will take good care of our tiny part of the universe, the earth.

  CONTENTS

  List of Figures and Illustrations

  Acknowledgements

  Preface

  PART I: PTOLEMY’S UNIVERSE

  Chapter 1

  The Babylonians: Earliest Observers of the Sky

  Chapter 2

  Greek Astronomy and the Birth of Natural Philosophy

  Chapter 3

  Ptolemy: The Shape of the Universe

  Chapter 4

  Crossing the Dark Ages

  PART II: NEWTON’S UNIVERSE

  Chapter 5

  Nicholaus Copernicus: Innovator or Traditionalist?

  Chapter 6

  Renaissance Astronomy: Tycho Brahe and Johannes Kepler

  Chapter 7

  Galileo Galilei: The Italian Connection

  Chapter 8

  Isaac Newton and the Scientific Revolution

  Chapter 9

  Exploring the Newtonian Universe

  PART III: EINSTEIN’S UNIVERSE

  Chapter 10

  Relativity: Special and General

  Chapter 11

  The View from Mount Wilson

  Chapter 12

  Edwin Hubble and the Expanding Universe

  Chapter 13

  The Big Bang

  Epilogue

  Further Reading

  Index

  LIST OF FIGURES AND ILLUSTRATIONS

  Constellations of the Zodiac. © Author’s own sketch.

  The celestial sphere. © Author’s own sketch.

  Retrograde motion. © Author’s own sketch.

  Measurement of parallax. © Author’s own sketch.

  Epicycle on a deferent. © Author’s own sketch.

  Kepler’s model of planetary orbits. © Astronomia nova, J. Kepler, 1595.

  Galileo’s notes on moons of Jupiter. © Siderius Nuncius, G. Galileo, 1610.

  Incorrect physics of centripetal motion. © Author’s own sketch.

  Einstein explains field equations. © Courtesy Brown Bros.

  Bending of starlight by the Sun. © Author’s own sketch.

  Possible futures of the universe. © Author’s own sketch.

  Eddington meets Einstein. © Courtesy of Leiden University.

  HR diagram. © Courtesy of George Abell.

  Hubble’s Law, 1929, 1931. © E. Hubble, M. Humason, 1931.

  Raisin bread analogy. © Author’s own sketch.

  Thermal radiation. © Author’s own sketch.

  Gamov’s letter to Penzias. © Cosmology and Microwave Astronomy, A. Penzias, 1972.

  ACKNOWLEDGEMENTS

  To my wife Patricia, companion for half a century, goes my gratitude for her total acceptance of this project. She gave me the greatest gift a husband could have to follow a dream: a two-year sabbatical from marriage to be a recluse while she used her talent and experience in Ethiopia to help modernize the country’s educational system.

  I would also like to thank three generous women who helped me during the two years of this book’s gestation:

  Nicole on
the sunny Kent coast for her support and chicken soup; Louisa in wet Glasgow for proofreading and encouragement; and Cynthia in leafy Hampstead for a writer’s sanctuary in the final stages.

  To my editor and friend, Leo Hollis, I offer my sincere thanks. He deserves most of the credit for the existence of this book. In addition to securing this prize commission for me in the first instance, he has advised, cajoled and creatively criticized my many false starts and ‘final’ drafts. Over the past two years, as I groped my way through forty centuries of stargazing and theorizing, his erudition, discipline, saintly patience and love of history were indispensable. He instilled in me the confidence that I could encapsulate the main elements of this remarkable story in 100,000 words or so. I probably will never tackle anything like this again. That is, unless Leo Hollis asks me to. But where do we go from here?

  I would finally like to acknowledge the continuous support of my wife and three sons, who have never lost faith in me. In order to hold my own in this creative family, I had to do something special. Unlike Bill Starbuck, I’m no good at rainmaking. So I wrote this book about the universe instead.

  Special thanks to:

  Jenny Doubt for being a painstakingly accurate copy-editor; and Mark McEvoy for preparation of the illustrations under intense deadline pressure albeit in the salubrious surroundings of the Tuscan hills.

  ‘Ptolemy made a universe, which lasted fourteen hundred years.

  Newton also made a universe, which has lasted three hundred years.

  Einstein has made a universe, and I can’t tell you how long that will last.’

  George Bernard Shaw

  (Introducing Einstein at the Savoy Hotel in London, 28 October 1930)

  PREFACE

  Who has not watched nightfall, when the Sun slowly descends below the horizon and, after several minutes, is enveloped in darkness. At that moment the scattering of sunlight by the Earth’s atmosphere gives way to a transparent sky. Stars, galaxies, planets and moons, quasars and pulsars appear. Humans have been studying these celestial objects since the beginning of life itself, and it is at this hour that astronomy enthusiasts are poised with their telescopes, binoculars and cameras to study the heavens, visible in all its glory.

  Stargazers are joined in a noble and 4,000-year-old ancient tradition of exploring the night sky. This pursuit began as astrology, when our ancestors attempted to describe what they saw in order to read omens and prognostications. This fearful probing of the stars then developed into astronomy, and now has become cosmology – the study of the universe as a whole. Initially, the stargazer’s aim was to record the changing face of the skies through the days, months, seasons and years. It was only later that a more complex explanation was sought, and models and plans of how the planets and stars moved in relation to each other were developed.

  It was not until the Renaissance that the first scientist began to study these models against what they saw in the firmament and began asking how and why the universe worked? Over the course of a century, knowledge was accumulated by men who have become so famous that their surnames are instantly recognizable: Copernicus, Tycho, Kepler and Galileo. These first modern scientists prioritized observation above received wisdom; experience over theory; and applied mathematics and geometry to theoretical models to reproduce the actual motion of bodies, both heavenly and terrestrial. Most notable for this approach is Isaac Newton, who produced a synthesis of the work of his predecessors, rounding off an era known as the ‘scientific revolution’. This critical advance in man’s intellectual activity was able to establish principles that were missing from earlier work in science and also to point the way to the extraordinary, abstract concepts to follow in the nineteenth and twentieth centuries, culminating in the work of Einstein.

  The study of science had changed, and now astronomical explorers ask not just why and how, but what: Of what were these entities composed? Why did they behave as they did? These questions would demand new ways of looking at the universe, and the development of instruments capable of measuring and recording the heavens. It was Galileo who first pointed his telescope into the night sky and, in so doing, was able to revise what we know about the solar system. This technological revolution would be at the heart of the next era of exploration.

  In the British Isles, visionaries like William Herschel and later in 1845, Lord Rosse, built massive versions of this ‘optical tube’ to look at mysterious celestial objects called nebulae, or clouds. In the next century, inventors applied their skills to extract as much information as possible from the faint beams of light collected by telescopes. Astronomers studied the characteristics of individual stars using new optical techniques such as spectroscopy and photography. With these technological advances, astronomy had become an experimental science.

  Still larger telescopes were designed when it became apparent that these methods could determine not only the composition of stars, but also their distance from the Earth and even their speed through the cosmos. American scientific entrepreneurs took up the challenge, squeezing large endowments from private philanthropists to build gigantic machines in the mountains of California.

  Finally, observers such as Edwin Hubble and theorists like Einstein joined forces and the golden age of astronomy – the twentieth century – was at hand. Cosmology, the study of the whole universe, was no longer the abstract province of philosophers, and attracted all types of men and women to study the nature and structure of the universe.

  This book, which attempts to answer the question of how we discovered the universe, is the story about the individuals whose curiosity, patience and determination have come to characterize the human intellectual spirit. It is an extraordinary story that almost spans the complete history of human civilization. It begins in the ancient society of Babylon between the Tigris and the Euphrates, long considered the cradle of civilization, and continues up to the present day, to the high-tech observatories of the modern world. It is, in effect, the story of science itself.

  With such a vast canvas, it has been important to find a narrative through the data. Like the night sky, some stars are brighter than others, and in the history of astronomy this also holds true. It is the story of great people – inventors, theorists, philosophers, noblemen and commoners, librarians and technicians – who have all made their mark on the story of the universe. Stargazing has attracted all types of people, and each of their respective personalities shapes this narrative. Despite their many differences, they all share a determination to venture into the unknown, and return with new knowledge.

  Priority has been given to the art of observation, the essential characteristic of all good astronomy. Throughout its 4,000 years, stargazing has revealed new frontiers through combining observations of the heavens with a solid theoretical interpretation of the collected data. One without the other is just bad science – seeing and thinking must continue to go hand in hand.

  Thus silent, patient observers still stand at the horizon waiting for darkness. But now those observers are much less confused and fearful, standing upon the shoulders of countless previous generations. This story of how we came to be at home in our universe, is also a plea to continue to seek deeper understanding of our cosmos, our galaxy, our planet, ourselves.

  PART I

  PTOLEMY’S UNIVERSE

  1

  THE BABYLONIANS: EARLIEST OBSERVERS OF THE SKY

  Two famous rivers, the Tigris and the Euphrates, meet in the area historically known as Mesopotamia, the ‘land between two rivers’. Flowing south-eastward, the rivers approach each other to form a single valley before then proceeding in parallel channels for the greater part of their course. They unite again shortly before reaching the Persian Gulf. The delta from these rivers forms a plain about 170 miles (274 kilometres) long. Much like the Nile in Egypt, the delta offered many advantages to early inhabitants, attracting settlements for thousands of years. The fertile valley yielded abundant harvests, workable clay and the nutritious fruit of the date palm.
Though large stone deposits were lacking, the early settlers used the local clay for building and writing material.

  During the 1870s and early 1880s, numerous clay tablets from Babylonian archaeological sites found their way to antique dealers in Baghdad. The tablets had been found in the ruins of the ancient Assyrian city of Nineveh, part of the royal archive from the most famous library in the ancient near East. The library was built by King Assurbanipal who reigned during Assyria’s ascendancy in 8 BC. This historical treasure was completely destroyed when a combined force of two other races, the Medes and the Chaldeans, sacked Nineveh in 612 BC burying the library completely and robbing future generations of its royal archive. However, the flames thought to have destroyed the library are said to be responsible for firing the clay tablets into permanent records that lasted for centuries.

  This unique collection includes tablets found in the ruins of the royal archive from the most famous library in the ancient near East. One set of seventy tablets from Nineveh revealed a vast programme of astronomical observations, which had been carried out in the second millennium BC during the Old Babylonian Period. Most of the tablets deal with interpretations of lunar and solar eclipses, conjunctions of planets and comets, which the Babylonians took as dangerous omens. Others are concerned with planets and the stars. These old records had been copied and stored at Nineveh in order that the local scribes would be able to understand future signals in the heavens.

  What these tablets reveal is an unexpected link with an ancient scientific community dating back to before 1000 BC from which we can then establish a continuous link to modern cosmology. These early scientists were the first people whose observations and astronomical knowledge were accumulated over centuries in ancient Mesopotamia, eventually to be used by the Greek astronomer, geographer and mathematician, Hipparchus. Hipparchus’ work is linked to the present day via Ptolemy, Copernicus, Kepler and Newton.