IN the spring of 1905, a hundred years ago, a young man began the journey from obscurity to scientific stardom. Within a decade, the young Albert Einstein would be hailed as a genius who towered over his contemporaries, even in an era that had no dearth of brilliant minds in science. Soon the comparisons would begin to transcend his century, and he would take his place alongside Isaac Newton and Charles Darwin.
In that magical year, the 26-year-old Einstein, without a formal academic position and sustained by employment in the Swiss Federal Patent Office, was to publish four epochal papers within the space of seven months in the German journal Annalen der Physik , one of the pre-eminent scientific journals of his time. In these four papers, Einstein would initiate a revolutionary turn away from classical physics, abandoning some of its most cherished assumptions. The seemingly effortless ease and rapidity with which this was accomplished and the sheer magnitude of what resulted thereby appears even today, in the age of rapid scientific advance, breathtaking.
Physics would no longer be the same after 1905. The comforting link between mundane sensory experience and the fundamental laws of nature that had existed in Newtonian physics even after the Copernican revolution would now be lost forever. With Einstein began the age when, as he himself was to emphasise, the fundamental concepts of science would be "farther removed from the sphere of immediate experience, if we aim at a profounder understanding of relationships".
A century after the work that placed Einstein firmly in the ranks of the greatest names in the history of science, His legacy is ubiquitous in science and his fundamental contributions very much a part of the standard lore of physics. Paradoxically though, physics has advanced so far down the road that he first took, and the frontiers of his discipline have extended so far beyond where they were in his day, that we are perhaps in danger of missing the extraordinary transformations that Einstein effected in our fundamental understanding of nature.
What did Einstein accomplish in those four papers of 1905?
Three days after his 26th birthday, on March 17, Einstein completed the first of this remarkable series. Received by the journal on March 18, and published on June 9, the paper was titled "On a heuristic point of view concerning the generation and conversion of light". This paper was the first shot in the quantum revolution. In this paper Einstein framed, unambiguously, the hypothesis that light in its interaction with matter behaves like a particle with a discrete amount or `quantum' of energy proportional to its frequency. Over the next two decades the hypothesis was to be verified experimentally, leading to his Nobel Prize for physics in 1921.
The second paper, received by the journal on May 11 and published in the issue of July 18, concerned itself with the explanation of Brownian motion, the phenomenon of random motion executed by particles suspended in a fluid. The work was an immediate outgrowth of his doctoral thesis, which itself was completed only a few days earlier, on April 30, and submitted to the University of Zurich. This paper, as Einstein cheerfully noted in a letter to a friend, once and for all settled the question of the reality of atoms. It also developed methods that lie at the root of modern statistical physics, particularly in the study of systems out of equilibrium.
Some time in mid-May, Einstein had that definite moment of discovery that opened the road to the formulation of the Special Theory of Relativity. The result was the third paper, received by Annalen der Physik on June 30 and published on September 26, titled "On the electrodynamics of moving bodies". It abolished the notion that electromagnetic radiation required some kind of medium, the `ether' as it was known, for its transmission. Indeed, the problem of the `ether' had occupied the young Einstein for almost a decade and was the subject of a precocious essay that he sent to his uncle, Cesar Kock, in Belgium in 1895. Einstein also postulated that the velocity of light was always constant, independent of the velocity of the emitter.
In the resulting unification of space and time, Einstein advanced decisively beyond Newtonian mechanics, a process that he was to complete with the General Theory of Relativity in 1915. The mathematician Hermann Minkowski, one of the few teachers from his university days that Einstein respected, noted in an influential review of the Theory of Relativity in 1908: "The views of space and time which I wish to lay before you have sprung from the soil of experimental physics and therein lies their strength. They are radical. Henceforth space by itself and time by itself are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality" (as quoted in the pre-eminent scientific biography of Einstein, ` Subtle is the Lord... ': The Science and Life of Albert Einstein , by Abraham Pais, Clarendon Press, Oxford, 1982).
In the fourth paper, received by the journal on September 27 and published on November 21, Einstein announced the result that energy is proportional to mass, as a consequence of the Special Theory of Relativity. The constant of proportionality is the square of the speed of light. By then, on July 27, Einstein's doctoral thesis had been accepted, and he sent it for publication to Annalen der Physik , which received it on August 19. It was published only the next year after some additions made at the request of the editors.
Within months of the publication of these four papers of 1905, Einstein had arrived in the academic world of his time. By 1906, he was in correspondence with leading physicists of his day like Max Planck, who was to describe Einstein some years later, while recommending him for a professorship, as a `modern Copernicus'. Contrary to some variants of the popular myth, Einstein's work of that year found rapid acceptance in the world of science. Three years later Einstein was to leave the patent office to enter the academic world, but the legend of the unknown patent clerk, the lonely genius, who effected a complete revolution in science was born.
Einstein, in 1905, was not unaware of the scientific currents of his time, particularly in relation to the questions that were uppermost in his mind. There were also significant gaps, leading occasionally to the rediscovery of known results. In later years, he was to reflect profoundly on the history and philosophical and scientific antecedents of the problems he addressed in the papers of 1905. But in that extraordinary year, Einstein was to leap forward with brilliant simplicity beyond the science of his day.
There was one more brilliant success that awaited Albert Einstein, the second phase of his radical departure from classical physics. In 1915, he finally succeeded in extending the Theory of Relativity to matter in acceleration, resulting in a new theory of gravitation, where mass was identified as the curvature of space-time. But this was hard won success, and the final work was built on a succession of earlier papers, some of them in collaboration with Marcel Grossman, his friend from his university days. The confirmation of this theory came from the solar eclipse expedition of 1919, data from which observed the bending of light from the stars by the sun, which had been predicted by Einstein's new theory of gravity.
Subsequently, Einstein's scientific journey was to become more complex and difficult. He never reconciled himself to the eventual form that quantum mechanics took in the hands of Werner Heisenberg, Paul Dirac, Erwin Schrodinger and Max Born, under the influence of Niels Bohr.
While he was gradually convinced that quantum mechanics was not inconsistent, he nevertheless believed that it was incomplete. Einstein liked even less the application of the methods of quantum mechanics to electromagnetic fields. The man who initiated the quantum revolution remained unhappy with what became of it in the hands of its Jacobins.
Thus began an isolation from the mainstream that was to intensify in his years at the Institute of Advanced Study at Princeton in the United States, where he settled after leaving Nazi Germany in 1933. His attempts in his Princeton years to formulate a unified theory of gravitation and electromagnetism did not make much progress and was considered a fruitless project by many of his contemporaries. Twentieth-century science pushed forward far more relentlessly than the science of the 17th or even the 19th century, and the manner in which scientific developments outran Einstein in his later years was not a fate that befell a Newton or a Maxwell in their lifetime.
But Einstein's larger vision undoubtedly set the agenda, if only in part, for subsequent developments that came much later. The search for a unified theory of all fundamental forces has now become an integral part of the paradigm of fundamental physics. And in partial vindication of Einstein, the integration of quantum mechanics and the General Theory of Relativity on the basis of some fundamental principles remains a challenge despite evidence of some progress in recent decades.
After the spectacular affirmation of Einstein's theory of gravity by the solar eclipse expedition of 1919, a world wearied by the First World War greeted Einstein as a new popular hero. There was intense interest worldwide in Einstein and his work. In India, it resulted in the publication of the first-ever English translation of the papers of Einstein and Minkowski by Satyendranath Bose and Meghnad Saha, with a foreword by P.C. Mahalanobis.
Even prior to his rise to fame, Einstein had begun to step out into the world of public affairs, signing a manifesto against German militarism in 1917. Einstein was to be a pacifist all his life, except for the period that the Nazis were in power, and was drawn naturally to the ideals of Gandhi. Though he signed the letter urging the U.S. President to develop the atomic bomb, he was horrified by its use. He was unwaveringly opposed to nuclear weapons and it was a cause that occupied him till the end of his days.
Einstein was one of the few intellectuals in the U.S. to speak up against the anti-communist witch-hunts of the McCarthy era. In 1949, he wrote a short note titled "Why Socialism?" for the inaugural issue of the communist journal Monthly Review , an act of considerable courage at a time when the U.S. was slipping into a phase of intolerance and anti-communist hysteria. For several years the Federal Bureau of Investigation (FBI) kept him under surveillance. Einstein, though, remained an undaunted champion of civil liberties.
Einstein, born in an irreligious Jewish family, had no great attraction for religion through most of his life. But he was a firm supporter first of Zionism and then the state of Israel and lent his name to several other Jewish causes through the years. Shocked by the Holocaust, which claimed the lives of several of his relatives including two cousins, he shunned all contact with Germany, the land of his birth, except for a few close friends.
What was the origin of Einstein's willingness to support causes that went against the mainstream and were certainly unpopular with those in positions of power? Perhaps it was an extension of his scientific spirit to the realm of human affairs, as Niels Bohr noted in his obituary comments on Einstein: "The gifts of Einstein are in no way confined to the sphere of science. Indeed, his recognition of hitherto unheeded assumptions in even our most elementary and accustomed assumptions means to all people a new encouragement in tracing and combating the deep-rooted prejudices and complacencies inherent in every national culture" (as quoted in Einstein Lived Here , by Abraham Pais, Clarendon Press, Oxford, 1994).
No scientist before him and few after him so entrenched themselves in the public consciousness as Albert Einstein did. He was a public icon, recognised by people across the world, in an era before television brought the world to everyone's door. The formula that will always be associated with his name is perhaps the one scientific equation that is easily recognised by anyone. Half a century after his death, his image even today is perhaps more familiar than that of most contemporary men and women of science.
In his lifetime, he acquired a moral stature that compelled the attention, albeit reluctant, of governments and political leaders when he spoke up on issues, which were not lacking in the first half of a century marked by social and political turmoil. From philosophy to the arts, intellectual life was not complete without engaging with his ideas and work.
Yet to Einstein himself, despite his considerable involvement in matters other than science, especially in his later years, his scientific work was always to be at the core of his being, the very definition of his persona. Nowhere is this clearer than in the substance and style of his "Autobiographical Notes" that he wrote for the volume Albert Einstein: Philosopher-Scientist edited by P.A. Schlipp (published by The Library of Living Philosophers Inc., Evanston, Illinois, USA, 1949). The note, which Einstein begins by describing it as "my own obituary", has no reference even to the bare facts of his life, apart from brief comments on his education and the intellectual influences of his childhood and youth. It is entirely devoted to a short account of his main work and the philosophical and scientific questions that led up to them.
He interrupts a critique of Newtonian physics in the note to remark: "`Is this supposed to be an obituary?' the astonished reader will likely ask. I would like to reply: essentially yes. For the essential in the being of a man of my type lies precisely in what he thinks and how he thinks, not in what he does or suffers."
Einstein continued to work at his desk on his scientific problems until the end of his life. Again contrary to myth, Einstein in the academic milieu was very much a professional scientist. His scientific writings number more than 300, a large output even by contemporary standards. In his last days at Princeton, he continued to be held in awe by his scientific colleagues, even if they did not follow what he said (as Einstein was to complain to his friend Johanna Fantova, a University of Princeton librarian), as he worked and lectured amongst them. He lived quietly, walking every day between his office at the Institute of Advanced Study and his home, where he was ministered to by his faithful secretary Helen Dukas. To the men, women and children of that little town, the grandfatherly figure was a gentle and benevolent presence.
Einstein died on April 19, 1955, at the age of 75, after a brief stay in hospital following a ruptured aneurysm.
T. Jayaraman is a theoretical physicist at the Institute of Mathematical Sciences, Chennai.
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