Einstein’s Theory Of Relativity

Feature, Modern Era

A Revolution in Physics

It was November, 1919. The War to End War had been over for nearly a year; England seemed to have little better to do than settle down and observe the first anniversary of the Armistice. Little else was happening, or so it seemed. The momentous anniversary was occupying most men’s minds, to the exclusion of all else.

Then, on the 7th of the month, the London Times came out with an unexpected headline. “Revolution in Science” it shouted, in big, black letters, “Newtonian Ideas Overthrown”. Breathlessly it went on to describe the previous evening’s meeting of the Royal Society, in which the results had been announced of an expedition to the Gulf of Guinea.

Surely, men thought, as they read on, surely no expedition to the Gulf of Guinea, even to the summit of Mount Everest, could be called “a revolution in science”? The Times was talking through its hat.

But by the end of the article, the man in the street, though he might be little wiser, was satisfied that something exciting had been happening in the Gulf of Guinea. (But where was the Gulf of Guinea?) No one could ignore so great a person as the President of the Royal Society, and he himself had said: “This is not the discovery of an outlying island, but of a whole continent of new scientific ideas, it is the greatest discovery in connexion with gravitation since Newton enumerated his principles.”

What the expedition had done was to verify the whole of Albert Einstein’s Theory of Relativity, the astonishing theory of highspeed motion, the new, half-understood, Physics which seemed to unify all the branches of the subject. A few observations of the stars, viewed from Guinea, had thrown over almost the whole of the old Newtonian theories; proved them, while adequate to deal with occurrences on the earth, quite inadequate to deal with objects moving at tremendous speeds, speeds approaching the 186,000 miles a second of light.

One of Einstein’s more bizarre calculations, which the Expedition now proved correct, was that a clock, or a time-keeping mechanism of whatever construction, which happened to be travelling at a speed of 161,000 miles a second, would be registering time at exactly twice the rate of a clock which was, relative to it-stationary. It would register that speed simply because time itself had speeded up. And not only time altered at these speeds; so did dimension and mass. At this same speed a man travelling head-first through space would be exactly half his usual length. (But as any yardstick he might carry to verify this alarming fact would have shrunk by the same amount, he would be unaware of the change.)

Einstein had proved this to himself, and many things like it, entirely through a process of reasoning and mathematics. None of these phenomena had been observed or even suspected, apart from a peculiarity in the orbit of the planet Mercury, which his theories explained. There seemed little chance of checking on the behaviour of objects at the speed of light, but it was agreed, reluctantly at first, that if light could be observed to bend as it passed near the sun, a phenomenon predicted from the same calculation and which most scientists considered ridiculous, then the whole theory could be taken as accurate.

The 1919 eclipse, long predicted, provided just the right opportunity. It would be total, that is to say, the whole of the sun would be obscured by the moon, in a latitude near the equator, and two expeditions accordingly set sail for that latitude. One went to northern Brazil, the other to the Gulf of Guinea, off West Africa, each as insurance against weather conditions which might affect the other. It was calculated that with the sun’s light temporarily blotted out by the moon, pictures could be taken of the bright group of stars through which it was passing. The apparent position of these stars could then be compared with pictures of the same stars taken at another time and by night, in London, when they were far from the sun and therefore much less exposed to its gravity.

Though Einstein himself seems to have been unmoved, he had no doubts about his theory, there was consternation, then rejoicing, among others when the pictures from the eclipse proved it. Yes, the star-images on the photographic plate had been deflected by exactly the amount Einstein had calculated, in other words, their light, passing the sun, had been deflected by its gravity. There could no longer be any doubt about the Theory of Relativity.

And yet, as the President of the Royal Society went on to say, “I have to confess that no one has yet succeeded in stating in clear language what the Theory of Relativity really is.” No one could. A few scientists understood, the consequences of this new, all-embracing theory within their own special fields; none could as yet grasp the meaning of the theory itself.

Yet, a few years later, the theory was the standard, essential, tool of every physicist, and the words “Einstein” and “Relativity” were being bandied about by half the world. At least one reason lay in the remarkable character of Albert Einstein himself, a kindly, intelligent, yet strangely naive man, with great charm. It was this character which gave Relativity a publicity no other theory in Physics ever enjoyed.

He was born on 4 March, 1879, in the German town of Wurttemberg, but left with his parents when he was only a year old, to move to Munich in the south. Here his father started a small electrochemical factory with his brother, Albert’s uncle. It was from this uncle, rather than from his father, that the boy got his interest in science and mathematics. From his mother, who was a musician, he inherited a deep love of music.

The family was Jewish and the boy was brought up in that faith, but as there was no convenient Jewish school he was sent to a Catholic one and absorbed that faith as well. Quite probably this peculiarity in his upbringing accounted for his life-long hatred of prejudice and bigotry, his reluctance to become identified with any nation or group. He became fascinated by mathematics, largely through his uncle who set algebraic problems to him in the evening, much as other uncles might react stories. “The animal we are hunting is hidden. We will call him ‘x’ for the moment, but we’ll get him, all right.”

When he was fifteen his father lost money and moved south again, to Milan, but Albert, who was at the best school in Munich, was left behind to get his diploma. To the annoyance of his parents he decided to follow them without waiting for it. As by now his father had lost more money and was quite unable to keep him, he was despatched north again, to the Polytechnic Institute of Zurich, in the hopes that this might fit him for some scientific career. After these studies, during which he married a fellow student from Hungary, he had difficulty in getting the job he wanted and eventually could only get one with the Patent Office in Berne. Loving his new country, he renounced German citizenship. He and his wife had two sons, and although the marriage between this happy-go-lucky Bohemian who forgot to wear matching socks or comb his hair, and his reserved, suspicious East European wife, had begun to falter, these sons kept it alive.

It was while he was at Berne, with time on his hands at the Patent Office, that Einstein published his first two papers, on the Transformation of Light and the Electrodynamics of Moving Bodies. These caused a small stir in the academic world. How could a petty official in, of all places, the Patent Office, make such researches, have the intelligence to set them out in this fashion? Perhaps, if they were genuine, he should be given some University appointment?

He was appointed to the University of Zurich, and here, where one had to keep up appearances, wear matching socks and a well-pressed suit, he was miserable, and very poor. As he was to remark years later, recalling these Zurich days, “In my relativity I set up a clock at every point in space, but in reality, I found it difficult to provide even one in my room.”

From Zurich, working hard on his theories, to Prague, thence back to Switzerland and to the old Polytechnic, as a teacher. By now he was a world figure. His Special Theory of Relativity, the precursor of the General Theory, had been published in 1905. He was appointed Director of the new Kaiser Wilhelm Institute in Berlin, and although as a Jew he was beginning to distrust Germany he accepted the post with its much higher salary, its opportunities for research.

His wife, Mileva, refused to go. She knew she would hate Berlin, and in any case they were agreed the marriage had failed. She and the boys stayed behind, and shortly afterwards divorce came through. Fortunately for Einstein, there was a distant cousin living in Berlin, and she took good care of him. A friendly, happy person, she was amused by her cousin. A year later he married her.

He was in Berlin for twenty years, from 1913 to 1933, and it was during these years that he developed his Theory of Relativity from the Special Theory of 1905 to the all-embracing General Theory. The assumption of the former was that the velocity of light and indeed ail the laws of nature are the same in all co-ordinate systems moving uniformly, relative to each other. In General Relativity, this was extended to co-ordinate systems in nonuniform (i.e., accelerated) relative motion.

General Relativity also shows that if matter is converted into energy, the energy released is shown by the simple-seeming formula, E equals mc2, where c is the velocity of light and m the mass. The formula shows that a small mass can be converted into a huge amount of energy. It shows, mathematically, the possibility of making an atomic bomb, and nothing could have been less to Einstein’s liking than this. It also gives the secret of the sun. If it were really burning, as people thought, it should have been consumed years ago; in the atomic reaction Einstein substituted, huge quantities of light and heat could go on being created, with the loss of only a very small mass.

His theory began to be accepted during the war, and in 1919 when the Guinea expedition proved it to the satisfaction of all, he became a world figure. He was beginning to hate nationalism as well as racialism and now he wrote: “By an application of the Theory of Relativity to the taste of the reader, to-day in Germany I am called a German man of science; in England I am represented as a Swiss Jew. If I come to be regarded as a bete noir, the description will be reversed and I shall become a Swiss Jew for the Germans, a German for the English.”

By 1933 he reluctantly left Germany with its Nazi Jew-baiting, and settled in Princeton, New Jersey. His second wife, Elsa, to his eternal sorrow, failed to make a transition to the new way of life and literally pined away, dying three years later. He stayed on in Princeton, at the New Institute of Advanced Study, until 1955, when he too died. He was mourned universally as the world’s, the century’s, greatest man of science, and also, though this has little bearing on his huge Theory, as the most approachable. To a colleague in Princeton who was late for an appointment in the town, he remarked, “Don’t worry, don’t worry, why should I mind that you are late meeting me? Am I less capable of reflecting on my problems here than at home? Here”, showing a much-chewed pencil, “here is my laboratory.”

Relativity, which has transformed physics, has required great changes in our traditional handling of the concepts of space and time. Two events happening in different places may be judged to be simultaneous by one observer and not by another. Simultaneity, Einstein pointed out, is relative to the observer, and four quantities are now involved with it: the three usual spatial dimensions and the fourth dimension of Time.

He was working, before he died, on a new theory, one which would link gravitation with electro-magnetism. The theory as he left it has not been universally accepted, but there is little doubt among physicists that a new theory, embodying Einstein’s Relativity, is needed to embrace a connexion between these two phenomena. Without the Theory of Relativity this sort of speculation would be quite impossible; the true workings of the universe in which we live might never have been comprehended.