Died: 1955, Princeton, New Jersey
Major Works: Scientific papers, originally published in German: "On a Heuristic Viewpoint Concerning the Production and: Transformation of Light" (1905), "On the Motion of Particles Suspended in a Liquid" (1905), "On the Electrodynamics of Moving Bodies" (1905), "Planck's Theory of Radiation and the Theory of Specific Heats" (1907), "On the Relativity Principle and its Consequences" (1908), "On the Present State of the Radiation Problem" (1909), "The Foundation of the General Theory of Relativity" (1916), Considerations on the General Theory of Relativity" (1917), "On the Quantum Theory of Radiation" (1917), "Relativity: The Special and General Theory" (1920), "Quantum Theory of Monatomic Ideal Gases" (1925), Can Quantum Mechanical Description of Physical Reality Be Considered Complete? (1935)
Coordinate space and time are not absolute, and the simultaneity of events is observer-dependent, but the speed of light is invariant (the special theory of relativity).
Mass is a form of energy, interchangeable with other forms according to the relation E = [mc.sup.2].
Gravitational force is locally indistinguishable from acceleration of the frame of reference (the equivalence principle).
Gravitational fields are manifestations of curvature of spacetime, which originates in the stress-energy of the material contained therein (the general theory of relativity).
Motion of massive bodies will create gravitational waves.
Light exhibits quantum properties in the photoelectric effect, with photon energy related to frequency by = hf.
Atoms can be stimulated by the passage of light to emit more photons of the same energy.
Observations of diffusion can be used to determine the dimensions of molecules.
A monatomic gas such as helium should condense at low temperature into a superfluid state.
Understanding of gravitation, electromagnetism, and other interactions should be sought in unified-field theories.
Albert Einstein's mastery of physics and his influence on the form it takes today cannot be matched by any other figure in history except Isaac Newton. The transformation of classical into modern physics is due in large part to Einstein's work. He is also probably the most famous physicist of all time, and his story is deeply embedded in the popular image of that profession He is an appealing figure because of his gentle, affable character and interest in humanitarian causes coupled with strikingly creative work and technical brilliance that keep him at the same time forever remote from true popular understanding.
Soon after Albert's birth, his parents moved to Munich, and there he spent his formative years. His father and uncle !were proprietors of a small business, designing and manufacturing electrical equipment. Here young Albert imbibed early both an interest in the nature of light and electricity and an appreciation for the importance of measurements. Though he is most famous as a theorist, in fact he retained a keen interest in experimental physics in his career. When the family business failed in 1894, the family moved to Italy for a new start. The fifteen-year-old son stayed briefly in Munich, but soon dropped out of school; at least one teacher who considered him a disruptive influence was glad to see him go. Albert spent a few months in Italy before heading to Zurich for further education.
Contrary to a common misunderstanding, there was little doubt at any point about Einstein's mental abilities. He did relate poorly to some retrogressive features of the German schools of the time, and he had the confidence to follow his own priorities about what he learned and how he went about it. He cared for mathematics only as a tool, for instance, being more interested in visual conceptualization and experiments in science. His failure to gain entrance to the Federal Institute of Technology (ETH) in Zurich on his first try has much to do with his taking the exams a year earlier than normal, on top of being a dropout. The year he spent in the progressive cantonal school in Aarau (1895-96) not only gave him automatic admission to the ETH but also provided experiences (especially in its unusually well-equipped new laboratory) much more suited to his mental development.
As a university student, Einstein again followed his own unorthodox path, and his talents were not sufficiently recognized for him to receive encouragement toward an academic career; he failed to win an assistantship to continue graduate studies. After brief experiences with high school teaching and private tutoring, he took a position in the Swiss patent office in Bern in 1902, where he worked for the next seven years. He continued to discuss physics with several close friends from student days, and tried writing some papers, which at first gave no promise of distinction. It was as an outsider that he stunned the scientific community with the three great papers of 1905, which in a single volume of Annalen der Physik remade the foundations of three distinct areas in physics.
Over the next two or three years, the importance of these papers was gradually assimilated. Einstein was finally encouraged to submit a dissertation to receive the doctorate (having had an earlier attempt rejected), and to apply for academic positions. After brief appointments at the University of Zurich and the German University of Prague, he returned to ETH; his recommendation for this position from Poincare commends "the facility with which he adapts himself to new concepts and knows how to draw from them every conclusion ... when presented with a problem in physics he is prompt to envisage all its possibilities." Einstein finally took a special research professorship at the University of Berlin in 1913. He resigned that position in 1933 as a direct result of abuses when Hitler came into power, and spent the rest of his life at the Institute for Advanced Study in Princeton, New Jersey. Einstein traveled widely; he missed the award ceremony for his own Nobel Prize in 1922, for instance, because he was lect uring in Japan at the time.
Einstein is most famous, of course, for his theories of relativity. The term is somewhat inappropriate, for the real heart of the theory lies in the study of invariants, those physical quantities that do not depend on the observer's frame of reference. Einstein actually created two quite distinct theories, the first of which (1905) is called special relativity (SR). SR is a theory of the nature of space, time, and motion, following primarily from careful examination of the meaning of simultaneity. Einstein realized that Newton's assumption of a fixed and absolute universal time was not the only reasonable possibility; if the speed of light provides a natural limit on how fast signals can travel, one should insist on an operational definition of how the readings on two spatially separated clocks can be related to one another. The consequences of this theory include the apparent mass increase and spatial contraction of moving bodies and apparent slowing of the rate of moving clocks ("time dilation"). The word "apparent" is crucial here, because the theory says these represent changes in the way events are described by particular observers, not actual alterations of the moving bodies. SR also led to recognition of the possible interconversion of mass and energy.
Many of the individual elements of SR had already been developed by Lorentz, Abraham, and Poincare, including in particular the mathematics of the Lorentz transformation of coordinates. But this work was burdened with being an elaborate extension of classical ideas whose meaning seemed to become more obscure as it proceeded. Einstein's revolutionary contribution was in starting afresh and giving an entirely new physical interpretation to the symbols involved; Peter Bergmann says its revolutionary importance is because it is "formally simple, yet conceptually deep." At first, the limited data available on fast electrons contradicted SR, but Einstein was so sure of the theory that he was unperturbed, and after several years new and better data proved him right By now, a vast array of results from many areas of physics confirms SR.
In attempting to overcome SR's limitation to inertial fumes of reference Einstein was led to general relativity (GR) This is a theory of gravitation, which differs from Newton's in saying that gravity is not merely a field that is created in space, but a modification of space time itself. The first step (1907) was to recognize the principle of equivalence: Being in an accelerated frame of reference would be indistinguishable from experiencing a gravitational field Gradually Einstein came to realize that this idea was best developed by supposing that gravity represents curvature of space-time, and that he would need much more powerful mathematical tools to describe this. With the crucial help of his friend Marcel Grossmann, he learned tensor calculus and then did much to extend it in developing GR. This work took several years, finally succeeding in late 1915 Einstein showed that GR should have three measurable effects that would differ from the predictions of classical physics: precession of the perihelion o f the planet Mercury's orbit, deflection of starlight passing close to the sun, and red shift of the spectral lines of light radiated by a massive body. The first of these immediately resolved an existing puzzle, but it was several years before the second and third could be verified. The drama surrounding an expedition to observe a solar eclipse m 1919, and the subsequent announcement that Einstein's prediction of light bending had been verified, made him a worldwide celebrity. While the number of experiments in which GR can be critically tested remains small, some of them today can be done with high accuracy, and their support for GR appears to be strong.
Three further consequences of GR are of particular interest, two of them having first been pointed out by Einstein himself. In 1916 and 1918, he wrote two papers about gravitational waves, setting out important information about their nature and the circumstances of their production. In 1917, he wrote his first paper on cosmology, beginning the application of GR to the overall structure of the universe. And Karl Schwarzschild showed a solution of the GR equations that was the first example of what are now known as black holes. All three of these are presently areas of very active research.
Aside from relativity, Einstein's most important work was on early quantum theory. One of the 1905 papers gave a radical explanation of the photoelectric effect. Max Planck, in his explanation of blackbody radiation five years earlier, had with considerable reluctance used a formula suggesting that material substances can interact with radiation only by transfer of energy in finite amounts, not continuously. Einstein was willing to go much further in supposing that light itself comes in discrete packages of energy that we now call photons (light quanta). It was nearly ten years before careful experiments by R. A. Millikan provided strong evidence that Einstein's explanation was correct, and many physicists remained unconvinced of the literal reality of photons until discovery of the Compton effect in 1923. Einstein's 1905 work foreshadows the whole discussion of wave-particle duality that flowered after Louis de Broglie's association of wavelength with momentum in 1923. It was for the photoeffect that Einste in was cited in his Nobel award--relativity was still too controversial. In 1916-17, he did further important work in this area, dealing with the relative probabilities of absorption, spontaneous emission, and stimulated emission of light by atoms. The third of these provides the foundation for light amplification and thus for all the practical applications of laser technology.
It is ironic that in this work Einstein was one of the first to develop the description of atomic processes in probabilistic terms, ten years before statistical interpretation of the wave function came forward as central to the new quantum mechanics. Already in 1916 Einstein expressed discomfort at this element of randomness, and he never fully accepted that aspect of quantum mechanics; he was fond of saying "Der Herrgott wurfelt nicht"-- "God doesn't throw dice." His further contributions to this part of physics were in the form of valuable criticism rather than direct development: In an ongoing exchange of thought experiments with Niels Bohr, he forced the Copenhagen school to sharpen their arguments; and in 1935 he wrote a paper (with Podolsky and Rosen) proposing a paradox that remains central to ongoing discussion about the issues of completeness and reality in quantum theory. As Max Jammer has said, "No physicist had more to do with the creation of quantum mechanics than Einstein" --but having decisive ly influenced the rise and development of this theory, he then no less decisively denied its adequacy once it had gained general acceptance. This rejection represents his feeling not that quantum mechanics is incorrect but that it is incomplete; he always held out hope that some different kind of theory would give a more satisfying account of atomic behavior. This theory should not be a mere appending of "hidden variables" to quantum theory, but should establish new concepts from which the quantum theory would emerge as only a statistical approximation to the truth.
Einstein's scientific work was wide-ranging; other significant items include analysis of the "Brownian motion" of microscopic particles showing how it could be used to determine fundamental constants of nature, an early explanation of the specific heat of solids, improvements on the explanation of blackbody radiation, and development of the quantum statistics of identical particles. Only for Einstein would such accomplishments be of little enough relative importance to barely rate mention. There is one other major theme in his work, that of the unified field, which dominated most of his career after about 1925. He had the misfortune to attempt a very worthy program of theory-building at a time when available data were not yet sufficient (as they were in the 1960s) to suggest that the nuclear forces (rather than gravitation) were the best candidates to be combined with electromagnetic fields in a unified picture. If nothing else, his willingness to explore so many blind alleys in quest of the unified field th eory demonstrates that his distaste for quantum mechanics was anything but scientific "hardening of the arteries."
Dealing with such fundamental issues in physics as he did, Einstein was quite aware of the philosophical implications of his work and interested in expressing his views. Those views developed with time, so that one can be misled by conflicting quotes from different stages in his thinking. He was an admirer of Spinoza, and as a student was also quite taken with the ideas of Ernst Mach. He credits Mach's views for much of his inspiration in solving the tangled affairs of electromagnetism and mechanics by the creation of special relativity. But by the time he completed general relativity, he and Mach had grown rather sour on each other. This is one aspect of Einstein's development from an early empiricism and positivism toward more of a realist picture later on, though as Fine says, "Einstein's realism is not the robust metaphysical doctrine that one often associates with that label." He would call it instead a "motivational realism"; that is, Einstein's realism is not any one particular theory but a program of trying to construct realist theories in hopes of matching empirical data, even reaping the dividends of successful prediction. In a foreword contributed by Einstein to a translation of Galileo's Dialogue, he said, "There is no empirical method without speculative concepts and systems; and there is no speculative thinking whose concepts do not reveal, on closer investigation, the empirical material from which they stem. To put into contrast the empirical and the deductive attitude is misleading."
While Einstein certainly led one of the great intellectual revolutions of all time, he often denied the revolutionary character of his own work. This was partly a reaction against journalistic extravagance in describing that work. But it was also because he felt himself in the deepest sense to be truly carrying on the work begun by Galileo, Newton, and Maxwell. Holton suggests that some of the key elements in his success were an ability to adopt an unconventional point of view when needed to expose a fault in some nagging problem, a willingness to concentrate for years on a single problem without regard to contemporary fashion, and an ability to make great but sure-footed intuitive leaps to new basic principles or viewpoints. No less important was a flair for asking himself childlike questions about such simple things as space and time, and then taking those questions seriously; the most famous example is wondering how a light wave would appear if one traveled alongside it.
Once Einstein was thrust upon the public stage, he endured with good humor most of the inevitable misunderstanding and nonsense generated by the media. He protested, often in vain, that his theory of relativity had no application whatsoever to the social sciences, arts, or ethics. Without taking himself too seriously, he used many opportunities to make very personal statements about education, religion, pacifism, Zionism, and other issues of the day. In retrospect one can criticize some of these as naive, but on the whole we value them today for their reassurance that one of the most brilliant creators of abstract science could still be a reasonable, gentle, caring, and whole human being. His influence upon the world around him is to be admired along with his monumental physical theories.
Clark, Ronald W. Einstein: The Life and Times. New York: H. N. Abrams, 1971. Widely read popular biography, which is somewhat weak on insight into the scientific work.
Einstein, Albert. Relativity: The Special and the General Theory 1st ed., 1916. 15th ed. New York Crown Publishers, 1952. An account written by Einstein himself for the general reader who is not conversant with the mathematics of theoretical physics Although the reader may get lost from time to time and the going is difficult, the reward may be a fundamental grasp of the basic ideas that revolutionized physics.
Fine, Arthur. The Shaky Game: Einstein, Realism and the Quantum Theory. Chicago: University of Chicago Press, 1986. Chapters 1-6 examine at length the nature of Einstein's objections to quantum theory.
Friedman, Alan, and Carol Donley. Einstein as Myth and Muse. Cambridge: Cambridge University Press, 1985.
Hoffmann, Banesh. Albert Einstein, Creator and Rebel. New York: Viking, 1972. Recollections of a former assistant to Einstein, in collaboration with his long-time secretary Helena Dukas.
Holton, Gerald, and Y. Elkana, eds. Albert Einstein: Historical and Cultural Perspectives. Princeton, N.J.: Princeton University Press, 1982. Proceedings of a symposium on the centennial of Einstein's birth.
Pais, Abraham. 'Subtle is the Lord...': The Science and the Life of Albert Einstein. New York: Oxford University Press, 1982. A thorough and authoritative scientific biography by a physicist who worked alongside Einstein at the Institute for Advanced Study.
Pyenson, Lewis. The Young Einstein: The Advent of Relativity. Bristol: Adam Hilger, 1985. Chapters 1-3 are informative about Einstein's social and educational background, and chapter 9 about his early career.
Sugimoto, Kenji. Albert Einstein: A Photographic Biography. New York: Random House, 1989.