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  Einstein’s Masterwork

  Einstein’s Masterwork

  1915 and the General Theory of Relativity

  JOHN GRIBBIN

  with MARY GRIBBIN

  Published in the UK in 2015 by

  Icon Books Ltd, Omnibus Business Centre,

  39–41 North Road, London N7 9DP

  email: [email protected]

  www.iconbooks.com

  Sold in the UK, Europe and Asia

  by Faber & Faber Ltd, Bloomsbury House,

  74–77 Great Russell Street,

  London WC1B 3DA or their agents

  Distributed in the UK, Europe and Asia

  by TBS Ltd, TBS Distribution Centre, Colchester Road,

  Frating Green, Colchester CO7 7DW

  Distributed in Australia and New Zealand

  by Allen & Unwin Pty Ltd,

  PO Box 8500, 83 Alexander Street,

  Crows Nest, NSW 2065

  Distributed in South Africa by

  Jonathan Ball, Office B4, The District,

  41 Sir Lowry Road, Woodstock 7925

  ISBN: 978-184831-852-6

  Text copyright © 2015 John and Mary Gribbin

  The authors have asserted their moral rights

  No part of this book may be reproduced in any form, or by any means, without prior permission in writing from the publisher

  Typeset in Dante by Marie Doherty

  Printed and bound in the UK by Clays Ltd, St Ives plc

  Contents

  About the Author

  Introduction

  1 In the Beginning

  Early life; Breaking free; Einstein and the Poly; Rejection; Rescue

  2 The Annus Mirabilis

  The doctoral thesis; Jiggling atoms; Particles of light; The special one

  3 The Long and Winding Road

  The geometry of relativity; Moving on; In the shadow of a giant; On the move; First steps; What Einstein should have known; The masterwork

  4 Legacy

  Black holes and timewarps; Beyond reasonable doubt; Making waves; The Universe at large

  5 The Icon of Science

  Personal problems; Fame; A last quantum hurrah; Exile; Spooky action at a distance; The final years

  Further Reading

  Endnotes

  Index

  List of Illustrations

  1. Einstein’s mother, Pauline Einstein

  2. Einstein’s father, Hermann Einstein

  3. Albert as a boy, circa 1893

  4. Albert and Maja Einstein

  5. Marcel Grossmann, Albert Einstein, Gustav Geissler and Eugen Grossmann in Thalwil, near Zurich

  6. The house in which Einstein lived in Bern, 49 Kramgasse

  7. Albert with Mileva and Hans Albert

  8. Albert, circa 1912

  9. First Solvay Congress, Brussels, 1911

  10. Albert and Elsa Einstein aboard the SS Rotterdam en route to the US, 1921

  11. Eddington, Lorentz, Einstein, Ehrenfest and de Sitter, at the Leiden Observatory

  The most valuable theory of my life …

  The theory is of incomparable beauty.

  ALBERT EINSTEIN, 1915

  If Einstein had not produced the Special Theory in 1905, someone else would have done so within a short time, five years or so. That is the general situation with almost all scientific advances, they are in the air; if A doesn’t make them, then B certainly will.

  The General Theory is the startling exception, maybe the only one in [the 20th] century. It is agreed by the most eminent of theoretical physicists – Dirac has said so without qualification – that if Einstein had not created the General Theory [in 1915] no one else would have done so, perhaps not until now, perhaps not for generations.

  C.P. SNOW, IN CONVERSATIONS WITH EINSTEIN

  BY ALEXANDER MOSZKOWSKI

  About the Author

  John Gribbin was born in 1946 in Maidstone, Kent. He studied physics at the University of Sussex and went on to complete an MSc in astronomy at the same university before moving to the Institute of Astronomy in Cambridge, to work for his PhD.

  After working for the journals Nature and New Scientist, he has concentrated chiefly on writing books on everything from the Universe and the Multiverse to the history of science. His books have received science-writing awards in the UK and the US. His other biographical subjects include Erwin Schrödinger, Stephen Hawking, Richard Feynman, Galileo, Buddy Holly and James Lovelock.

  Since 1993, Gribbin has been a Visiting Fellow in Astronomy at the University of Sussex.

  Introduction

  In 1905, Albert Einstein published four scientific papers that had a profound influence on the science of the 20th century. Everybody knows Einstein’s name, and an equation from one of those papers, E = mc2, is the most famous equation in all of science. For another of his contributions that year, he received the Nobel Prize. All of this has resulted in 1905 being referred to as Einstein’s ‘annus mirabilis’, or ‘miraculous year’. If he had never done another stroke of scientific work after 1905, Einstein would still be remembered as a genius. But, amazing as these achievements were, none of this represented Einstein’s greatest work. Exactly ten years later, in 1915, he presented his masterwork to the Prussian Academy of Sciences – a theory of gravity, matter, space and time which we know as the ‘General Theory of Relativity’, and which he described as ‘the most valuable theory of my life’. It describes the evolution of the Universe, black holes, the behaviour of orbiting neutron stars, gravitational lensing and why clocks run slower on the surface of the Earth than in space. It even suggests the possibility of time travel. He completed this work in Berlin during the First World War, where he later suffered from malnutrition caused by food shortages resulting from the Allied blockade of Germany and was nursed by his cousin, Elsa, who became his second wife. The accuracy of his theory was confirmed by British astronomers, at a time when Britain and Germany were technically still at war. But even today the General Theory is less feted than the achievements of 1905, because it is regarded as ‘too difficult’ for ordinary mortals to comprehend. I hope to disabuse you of this misapprehension and make it clear why the achievements of the year 1915 should be at least as celebrated as those of 1905.

  The Special Theory of Relativity, one of the achievements of 1905, is ‘special’ in the sense that it is restricted and ‘only’ describes the behaviour of things moving in straight lines at constant speed. The names alone tell you that the General Theory is a bigger deal, but because of the widespread (mis)conception that the General Theory is too difficult for ordinary mortals to understand, the events of 1915 have been less feted than the events of 1905.a It is, in fact, easy to understand the basics of the General Theory, even if the equations have to be taken on trust, and this understanding should convince you – correcting the misconception that the Special Theory was Einstein’s greatest achievement – that Einstein’s greatest year was indeed 1915, not 1905. But I intend to demonstrate this by putting Einstein’s science in the context of his life and work both before and after 1915, including his breakthrough year of 1905.

  As ever, I am grateful to the University of Sussex and the Alfred C. Munger Foundation for providing, respectively, a base for me and a contribution towards my travel and other expenses. Thanks also to Estelle Asmodelle for help tracking down sources.

  John Gribbin

  https://johngribbinscience.wordpress.com

  Footnote

  a A point of pedantry: always the ‘General Theory’, never ‘general relativity’; it is the theory that is general, not the relativity.

  1

  In the Beginning

  Early life; Breaking free; Einstein and the Poly; Rejection; Rescue

  I
n 1905, Albert Einstein produced the most important package of ideas from any scientist since Isaac Newton. The iconic image we have of Einstein is the white-haired genius, a wise and fatherly guru, a cross between God and Harpo Marx. But in 1905 Einstein was a handsome, dark-haired young man (he celebrated his 26th birthday on 14 March that year), previously something of a ladies’ man but recently married, with a baby son. He didn’t even have a PhD at the time he published the scientific papers that made him famous.

  What made Newton and Einstein so special was that they didn’t just have one brilliant idea (like, say, Charles Darwin with his theory of natural selection) but a whole variety of brilliant ideas, within a few months of one another. There were other similarities between the two great men. In 1666, Newton celebrated his 24th birthday, and although he had already obtained his degree from the University of Cambridge, for much of 1665 and 1666 he had been unable to take up a Fellowship at Trinity College because the university had been closed by an outbreak of plague. So he had been working in isolation at the family home in Lincolnshire. In 1905, the 26-year-old Einstein had already graduated from the Swiss Federal Polytechnic in Zurich, but had been unable to obtain a post at any university. So he had settled for a junior post at the patent office in Bern, working in isolation on scientific topics at home in his spare time – and also, as he later admitted, during office hours.

  Especially in the theoretical sciences and mathematics, it is often true that people do their best work in their twenties, even if that work never matches the achievements of a Newton or an Einstein. But there the similarities between the two geniuses stop. Newton was a loner by choice, who made few friends and never married; although most of his great work was done in 1665–6, it was only published later, at different times, in response to pressure from colleagues who became aware of what he had achieved. Einstein was a gregarious family man, eager to get a foothold in the academic world, who knew the importance of advertising his discoveries and published them as soon as he could. It was his only chance of getting out of the patent office and into a university post. But what was the man later regarded as the greatest genius of the 20th century doing working in a patent office anyway?

  Early life

  Albert had been born in Ulm, in Germany, in 1879. In the summer of the following year, however, the family moved to Munich, in the south of Germany, where Albert’s father, Hermann, went into partnership with his younger brother Jakob in the booming electrical industry. Jakob had a degree from the Stuttgart Polytechnic Institute and provided the expert know-how for the business; the money to set them up came from the family of Albert’s mother, Pauline. Hermann’s role was on the administrative side, running the business. Jakob and his wife, Ida, shared a pleasant house on the outskirts of Munich with Hermann, Pauline and little Albert.

  Far from showing any signs of precocious genius, little Albert was so slow to learn to speak that his parents feared that there might be something wrong with him. It wasn’t until well after his second birthday that he began talking, but when he did he used proper sentences from the start, quietly working the words out in his head and whispering them to himself before speaking out loud. In November 1881, his sister Maja was born, and she later recalled his response to her arrival, reported to her by her mother when she was old enough to understand. It seems that Albert had been told he would soon have something new to play with, and was expecting a toy; on being introduced to his baby sister, he asked: ‘Where are the wheels?’a Although brother and sister developed an affectionate bond, young Albert was prone to occasional outbursts of violent temper, when he would throw things at the nearest person – all too often, Maja. Family legend tells of the time he hit her over the head with a garden hoe, and how at the age of five he chased his first violin teacher out of the house, throwing a chair after her. But the music-loving Pauline was tough and strong-minded enough to ensure that he carried on with the violin lessons whether he liked them or not, eventually instilling in him a love of music that provided a lifelong release from the strains of his scientific work. And he had talent – much later, when he was a sixteen year old at high school in Switzerland, a school inspector would single him out for praise, reporting that ‘one student, [named] Einstein, actually sparkled [in] his emotional performance of an adagio from a Beethoven sonata.’1

  The expression ‘tough love’ could have been invented to describe Pauline’s attitude to her children. When he was only four, Albert was given a guided tour of the neighbourhood by his parents, and from then on was not only allowed but encouraged to go out alone and find his way through the streets – although, unknown to the boy, they kept a distant eye on him on his first few solo expeditions. One of the first regular journeys he had to make was to school. The Einsteins were secular Jews and were unconcerned that the nearest school was Catholic, so that is where Albert received his first formal education, very much in the old-fashioned tradition of learning by rote and with strict discipline enforced by corporal punishment. Albert’s disenchantment with the school was strengthened when he was still only five years old and ill in bed. His father gave the boy a magnetic compass to relieve his boredom, and Albert became intrigued by the way in which the needle always tried to point to the north, no matter how he twisted and turned the instrument. He was fascinated by the idea of an invisible force that kept a grip on the compass needle, and baffled that none of his teachers at the school had shown him anything half as interesting. This helped to instil an early conviction that he was much better off working things out for himself than working within the system.

  Albert’s stubborn insistence on finding his own way in the world led to a curious development during his years at the Catholic school. At that time, the statutes of the city of Munich required all students to receive some religious education, and although Hermann and Pauline didn’t mind Albert attending a Catholic school, they drew the line at having him indoctrinated in the Catholic faith. So, to meet their obligations they got a relative to teach Albert about the Jewish faith – as they thought, just as a matter of form. To everyone’s surprise, Albert lapped it all up and became something of a religious fanatic, observing the Jewish rituals that his parents had abandoned, refusing to eat pork and making up hymns that he would sing to himself as he walked to school in the morning. This religious phase lasted until Albert was about twelve and had been a student at the local high school (Gymnasium) for two years. His loss of faith was a direct result of his discovery of science; but that discovery owed nothing to the high school, and everything to a young medical student called Max Talmey.

  Although Hermann and Pauline Einstein did not follow all the religious traditions of their nominal faith, there was one Jewish custom that they kept. At that time, there was a tradition among middle-class Jewish families of helping young students who might be struggling to make ends meet, and the Einsteins got into the habit of inviting Talmey, who came from Poland,b to dinner once a week. It was Talmey who introduced Albert, who was ten when they met, to the latest scientific ideas, discussing them with the boy as if he were an adult. Talmey lent books popularizing science to Albert, introduced him to algebra and in 1891 gave him a book about geometry. Einstein later described reading this book as the single most important factor in making him a scientist. He was gripped, fascinated by the way in which mathematical logic could be used to start from simple premises to construct truths, such as Pythagoras’ Theorem, that are absolutely true. Within a year, he had worked his own way through the entire mathematics syllabus of the high school. This rather left the school, as he saw it, as a pointless waste of time. He had also lost his faith in God and now, as a young teenager, saw religion as part of a deception played by the State in order to manipulate its people, especially the young.

  Albert had made a good start to his time at the Luitpold Gymnasium, finding it easy to keep up with his peers; but although this was one of the best schools of its kind, a combination of the rigid educational system, his loss of religious faith and his discover
y that he could leap ahead of the curriculum by working on his own led him to neglect his classwork. He still got good grades in mathematics, but couldn’t see the point of subjects like Classical Greek and gained a reputation as an impudent troublemaker. One family anecdote recalls that Albert’s father was summoned to the school to be told that his son was a troublemaker. When he asked what they meant, he was told ‘he sits at the back and smiles’.

  The situation at school came to a head in 1894, when the family business went bust. The firm had done reasonably well in the 1880s, like many other small businesses taking advantage of the booming demand for electrical equipment such as dynamos, lighting systems and telephones. But in the classic pattern of progress following the invention of a new technology, those small businesses were now being swallowed up by large firms, or going under in the face of competition from the giants, such as Siemens and AEG. It was a lack of capital, as much as anything else, that saw the Einsteins lose out in this competition. But before matters came to a head they had gained a reputation in southern Germany and northern Italy. Italy had not gone so far down the road towards domination of the electrical industry by one or two firms, and with the encouragement of one of their Italian colleagues Hermann, Jakob and their wives decided to move to Italy to start again. There was one snag. Albert, who was now fifteen, had three years left to complete at the Gymnasium, which would ensure his admission to a good university. A family decision was made to leave him behind in Munich, staying in a boarding house but with a distant relative keeping an eye on him.

  The result ought to have been predictable. Albert was lonely and miserable in Munich, and without family life to fall back on the school seemed unbearable. There was another worry. Albert had always hated the militaristic aspect of German society at the time, and as a young boy, scared by the sight and sound of marching troops, had once begged his parents to promise that he would never have to be a soldier. But the law then required every German male to undergo a period of military duty. The only escape was to leave the country and renounce his German citizenship before his seventeenth birthday; if he left later, he would be regarded as a deserter.