The Seekers: The Story of Man's Continuing Quest to Understand His World (43 page)

Einstein was well aware that he had bridged the worlds of mechanics and of electrodynamics. “The relativity principle in connection with the Maxwell equations,” he observed in 1905, “demands that the mass is a direct measure for the energy contained in the bodies; light transfers mass. A remarkable decrease of the mass must result in radium. This thought is amusing and infectious but I cannot possibly know whether the good Lord does not laugh at it and has led me up the garden path.” All these ideas had brought Einstein to his misleadingly simple equation, E = MC
²
, in one of his early articles. This was scientific shorthand for his momentous suggestion of the equivalence of mass and energy. What it said was that the energy contained in matter is equal in ergs to its mass in grams multiplied by the square of the velocity of light in centimeters per second. Which meant, of course, in view of the velocity of light (186,000 miles per second) that a small amount of mass is equivalent to a vast amount of energy. And which was horrendously demonstrated (with no participation by Einstein) at Hiroshima on August 6, 1945, when that city became the target of the first military use of an atomic bomb, with some seventy-five thousand people killed or fatally injured.

Moving on to a wider exploration of the relation of masses to one another, Einstein reexamined the meaning of gravity in the new electrodynamic world. His observation of “photons” suggested that light too consisted of “quanta,” which, like everything else, might be affected by “gravity.” If light was affected by some form of gravity, then time and space would have two different configurations—one when viewed from within the gravitational field and another when viewed from without. This brought Einstein to the foundation of his General Theory of Relativity—that gravitation was not a “force” (in Newton’s terms), but a curved “field” in a space-time continuum, created by the presence of mass. Then, as Ronald Clark puts it, looking from the earth into outer space is looking through distorting spectacles. These were the suggestions of Einstein’s article in 1916. Just as “special” relativity described events in a frame of reference moving uniformly in relation to the observer, so general relativity would explain events when the frame of reference was moving at accelerating speeds, and so might also describe events in a gravitational field.

* * *

Einstein became famous to the lay public not from the essential truth in his theories, but from a dramatic event, publicized throughout the world, that confirmed his arcane theories. On May 29, 1919, a British astronomical expedition, which included the famous physicist Arthur S. Eddington, was at Principe Island in the Gulf of Guinea in Africa to photograph an eclipse of the sun. For physicists it would be a dramatic and suspenseful occasion. It offered a rare opportunity for plain and visible confirmation of one of Einstein’s basic postulates about the nature of mass and of gravitation. If, pursuant to Einstein’s ideas, light was a form of energy and so had mass, light would be affected, like any other mass, by a gravitational field. And a beam of light would be deflected (curved) by the influence of a mass in its path. Einstein suggested that his theory could be tested and confirmed by observing the path of starlight in the gravitational field of the sun. But since stars are invisible by daylight, the only time when the sun and stars could be seen together in the sky was during an eclipse of the sun. Would starlight be deflected by the gravitational field of the sun? Here, in full view, physicists could confirm Einstein’s theory of the physical world.

Despite heavy rain at Principe Island, Eddington and other eminent astronomers on the spot managed to make six photographs of the eclipsed sun with the rays of stars passing by its edge. Einstein had proposed that photographs be taken of the stars whose rays seemed to border the darkened face of the eclipsed sun, in order to compare them with photographs of the same stars at another time. By Einstein’s theory, the rays of light from the stars around the sun should be bent inward, toward the sun, as the rays of light passed through the sun’s gravitational field. Then the effect seen by observers on the earth should be to shift the images of those stars outward from their usual apparent position in the sky.

Einstein had predicted that for the stars closest to the sun the deviation would be about 1.75 seconds of an arc. The photographs taken by Eddington’s group showed that the deflection of starlight in the gravitational field of the sun actually averaged 1.64 seconds of an arc. This was as close to perfect agreement with Einstein’s prediction as the margin of error of the instruments allowed. Eddington later called this—observing the confirmation of Einstein’s theory—the greatest moment of his life. When Einstein saw a letter from Eddington with the exact theoretical value of the light diffraction, he responded exuberantly, and with a characteristically cosmic perspective. “It is a gift from Fate,” he wrote to Planck on October 23, 1919, “that I have been allowed to experience this.”

When the findings of the eclipse expedition were publicized by journalists across the world, Einstein became an instant celebrity for a bewildered public. Even in Berlin, where the puzzling news had to compete with menacing political disorders, Einstein complained that the publicity was “so bad that I can hardly breathe, let alone get down to sensible work.” And
The Times
of London published an article entitled “The Fabric of the Universe” that described for the layman the cosmic revision that was now required.

On November 28, 1919,
The Times
published Einstein’s own answer to “What is the Theory of Relativity?” Which he concluded with his customary wit, “Here is yet another application of the principle of relativity for the delectation of the reader.” He observed, “Today I am described in Germany as a ‘German savant’ and in England as a ‘Swiss Jew.’ Should it ever be my fate to be represented as a
bête noire,
I should, on the contrary, become a ‘Swiss Jew’ for the Germans and a ‘German savant’ for the English.”

In his
Times
summary Einstein himself gave some clues to his momentous revision. Time and space were no longer absolute. “In the general theory of relativity the doctrine of space and time, or kinematics, no longer figures as a fundamental independent of the rest of physics. The geometrical behavior of bodies and the motion of clocks rather depend on gravitational fields, which in their turn are produced by matter.” This “new theory of gravitation,” he noted, “diverges considerably as regards principles, from Newton’s theory.” But its practical results, he observed, agreed so closely to Newton’s that it was hard to find data in experience to distinguish and confirm the new theory.

He noted three examples of data “accessible to experience,” all of which were—or soon would be—confirmed by experience. One was in the eccentric behavior of the planet Mercury, whose elliptical orbit around the sun deviated slightly each year in a way not explained by Newton’s laws. Einstein explained this deviation was due to the fact that the planet Mercury (lying closest to the sun) was small and traveled with great speed. By Einstein’s theory the intensity of the sun’s gravitational field and Mercury’s speed caused the ellipse of Mercury’s orbit itself to swing slowly around the sun (at a rate of one revolution every three million years), and this agreed with Mercury’s actual course. The second confirmation of Einstein’s theory was the effect of gravitation on light, shown by the photographs of the British eclipse expedition. His third prediction was “a displacement of the spectral lines toward the red end of the spectrum in the case of light transmitted to us from stars of considerable magnitude (unconfirmed so far).” This, too, was soon to be confirmed.

The results of the British eclipse expedition, when they were reported to the Royal Astronomical Societies on November 9, 1919, had a dramatic impact on the world of scientists. “The whole atmosphere,” Alfred North Whitehead reported, “was exactly that of the Greek drama.” “We were the chorus commenting on the decree of destiny as disclosed in the development of a supreme incident. There was dramatic quality in the very staging . . . and in the background the picture of Newton to remind us that the greatest of scientific generalizations was now, after more than two centuries, to receive its first modification. . . . a great adventure in thought had at length come safe to shore.”

While the public did not quite understand, they were ready to share the enthusiasm of journalists and famous scientists who acclaimed Einstein as prophet of a new view of the universe. “Lights all askew in the Heavens, Einstein Theory triumphs,” headlined
The New York Times
on November 10, 1919. Which the London
Times
matched by declaring, “Revolution in Science, New Theories of the Universe. Newtonian ideas overthrown.” When Einstein came to the United States on a lecture tour in 1921, at the request of Chaim Weizmann to raise money for the Palestine Fund, he was given the full celebrity treatment and was expected to speak wisely on all world affairs. Some irreverently called him “the P. T. Barnum of Physics.” That year he was awarded the Nobel Prize for Physics. In January 1933, when Hitler became chancellor of Germany, Einstein renounced his German citizenship, and in October he immigrated to Princeton, where he became the star of the new Institute for Advanced Study. And he soon became an American citizen. He was mildly amused by his celebrity, which he called “psychopathological” and shrugged off as being out of proportion to his achievement. But he took advantage of his prominence to rally support for peace and world government, which excited the ire of leading members of the Soviet Academy of Science. He spoke out against Hitler, and even gave up his pacifism when he saw the rising tide of fascist power. As late as 1952 he wrote a correspondent telling him to “condemn the military mentality of our time. . . . I have been a pacifist all my life and regard Gandhi as the only truly great political figure of our age.” He had reason to fear assassination by the German Nazis, who attacked him and his science simply because he was a Jew, and he needed the protection of bodyguards.

In 1939, when he learned of successful European experiments in splitting atoms of the uranium isotope 235, he saw the possibilities of German production of an atom bomb and learned of German efforts to control the supply of uranium. So he was persuaded to sign a letter to President Roosevelt alerting him to the atomic peril. He urged the president to use federal funds to secure a supply of uranium and speed up American experiments in this area. Although his theories had provided a scientific foundation for atomic fission, he never took part in the work of Los Alamos. When he learned of the dropping of the first atomic bomb on Hiroshima in August 1945, he exclaimed, “
Oh weh!
”—Oh, woe! But he remained somehow an incurable optimist about the human race and man’s capacities for a world of peace. “Since I do not foresee that atomic energy will prove to be a boon in the near future,” he wrote near the end of his life, “I have to say that, for the present, it is a menace. Perhaps it is well that it should be. It may intimidate the human race into bringing order to its international affairs, which, without the pressure of fear, undoubtedly would not happen.”

The relentless Seeker, Einstein never abandoned his quest for meaning, for an intelligible unity in the universe. Back in 1930 he had described his quest as rooted in what he called “cosmic religious feeling. It is very difficult to elucidate this feeling to anyone who is entirely without it, especially as there is no anthropomorphic conception of God corresponding to it.” And he had explained why he would never be wholly satisfied. “The individual feels the futility of human desires and aims and the sublimity and marvelous order which reveal themselves both in nature and in the world of thought. Individual existence impresses him as a sort of prison and he wants to experience the universe as a single significant whole.” Einstein remained troubled by the indeterminacy that quantum mechanics had seemed to introduce into physics. And which led him to believe that such a view must be only a transitional stage in man’s quest for cosmic understanding. In 1948 he explained his deep problem. “I still work indefatigably at science but I have become an evil renegade who does not wish physics to be based on probabilities.” He expressed his simple faith in many ways, summarized in his most quoted aphorism: “God does not play dice with the world.” And he amplified this by noting that “God is subtle, but he is not malicious.” He had faith that the God who created rational man must have created an intelligible universe. All of which seemed part of the cosmic mystery that he never ceased to admire and to reach for.

It was fortunate for the world of science that Einstein had lived when he did, just when the new physics of electrodynamics—Faraday and Maxwell—came to challenge the mechanistic physics of Newton. With his passion for unity—for “a single significant whole”—he had his task temptingly set before him. And he was the man for that season. “I am truly a ‘lone traveler,’ ” he confessed, “and have never belonged to my country, my house, my friends, or even my immediate family, with my whole heart; in the face of all these ties, I have never lost a sense of distance and a need for solitude—feelings which increase with the years.”

He was equal to the challenge of conflicting grand theories of the physical world. He saw it his task to bridge the gap between the old physics and the new—to draw on them both to reveal a newly significant unity. He had the patience, “the holy spirit of inquiry,” the sense of humor, and the faith that he was treading an endless path. For the last decades of his life he remained in quest of a unified field theory that would somehow combine the Newtonian gravitational field with the recently discovered electromagnetic fields.

He never ceased his seeking. On April 17, 1955, doctors had given up efforts to save him by operations to stop his internal bleeding, and he must have known he was at the point of death. He asked to see his equations and his unfinished statement declining the presidency of Israel. He reportedly picked up his equations first and complained to his son at his bedside, “If only I had more mathematics.”