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by Ansar Fayyazuddin (Against the Current)
ALBERT EINSTEIN HARDLY needs an introduction. A popular culture icon, his name, his disheveled appearance in late life, his theory of relativity are synonymous with genius. It may be hard to imagine a physicist as a popular culture icon, Time's Person of the Century (for heaven's sake); yet no other figure of the 20th Century comes to my mind, with the possible exception of Picasso, whose legacy is so indisputable as to qualify for the position of something so improbable as Person of the Century.
As a culture we are very much taken with Einstein whether we understand him or not. It may very well be that the supposed inscrutability of his body of work confirms Einstein's status as genius as it does, mutatis mutandis, for Picasso.
This year marks the 100th anniversary of Einstein's most revolutionary year of scientific research.
The end of the 19th Century brought to a close a century of incredible discovery. The basis for what is known as "classical Physics" was laid in the 19th Century. Physics seemed to be a finished subject then. There were still unsolved puzzles but none of them appeared to be beyond the reach of already known Physics.
Little did anyone suspect that these puzzling details were the seeds leading to the complete transformation of what came to be known as "classical Physics." Einstein's work contributed directly to the 20th Century revolution that was about to take place.
Physics at the turn of the century was a combination of Newton's laws of mechanics, his theory of gravity, a theory of electricity and magnetism unified in Maxwell's equations, and thermodynamics. Light was understood to be an electromagnetic wave described by Maxwell's equations—the corpuscular (or particle) theory of light no longer in vogue.
Conservation of energy between different forms—chemical, electrical, mechanical—was firmly established and encoded in the First Law of Thermodynamics.
1905 was a remarkable year. In many ways we all long for that year. It was in a period of incredible optimism in Europe—the center of industrialization. What we might call the modern viewpoint matured during these early years of the 20th Century. Changes brought about by the second industrial revolution transformed everyday life completely, especially in the cities.
Electrification, the network of railroads connecting far-flung places, the birth of photography and cinema all contributed to an ethos of progress. All of this occurred at the cost of the constants of traditional life. But at the beginning of the century the fruits of the sacrifices of industrialization seemed at hand and a new, better world seemed just a breath away.
This optimism was embedded in a culture of uprootedness. The "constant revolutionizing of the means of production" that Marx and Engels talked about, and its jarring effects on the psyche described so lyrically in the Communist Manifesto, were much more true then than sixty years earlier when the Manifesto was written. These dislocations, physical and mental, found expression in a variety of forms including the art of the early 20th Century.
The revolution that was just starting to take place in Physics contributed to the modernist ethos of the time. On the one hand the bold steps that Physics took seemed to leave the old world far behind. On the other, Physics turned its attention to phenomena not directly observable by the unaided eye.
In so doing, Physics was no longer concerned with the experiences of everyday life. The shift away from everyday experiences to the nether world of atoms, and of objects traveling close to the speed of light, established a rupture between the concerns of traditional and modern Physics. This rupture mirrored the one experienced by the European working class from its traditional and secure place in the feudal economy to a new ever-changing one over which no one seemed to have any control.
In the year 1905 Einstein published five papers. Each one of them was a landmark. They touched on three distinct areas of Physics. Two of his papers dealt with the atomic nature of matter; another two concerned what came to be known as the "special theory of relativity;" and his fifth paper contributed directly to the Quantum Revolution whose groundwork was being laid then.
Brownian Motion and Atomism At the end of the 19th Century, while a section of the Physics community accepted the possibility of matter being built out of atoms, it was not a generally accepted point of view. There were still many who thought that matter was continuous and not made up of discrete atoms. (See note 1)
Even by the turn of the century, the atomist conception of matter had met with a number of successes. Most notably the kinetic theory of gases was able to account for thermodynamic properties of gases. In this view heat was conceived as the energy associated with the motion of the constituent atoms, while the thermodynamic (or macroscopic) properties of gases (such as pressure) were due to the collective behavior of their atomic constituents.
Despite these successes, a positivist philosophical inclination held sway in some influential circles denying any reality to the atomic hypothesis in the kinetic theory of gases. Thus atoms in this model were thought of as convenient mathematical fictions, which allowed one to calculate interesting quantities but did not refer to real physical objects.
Brownian motion is the random motion of small particles suspended in liquid that can be observed with the help of a microscope. This motion was a well studied phenomenon, but lacked a convincing theoretical explanation.
Einstein in one of his papers from 1905 provided a theoretical explanation. He showed that using the atomic hypothesis one can show that the random jiggling of a suspended particle can be attributed to it being kicked in random directions by the atoms in the suspending liquid. The main significance of Einstein's work is that he provided a concrete test of the atomic hypothesis.
What is particularly interesting about Brownian motion, as a test of the atomic hypothesis, is that Brownian motion concerns the motion of particles visible under a microscope (such as pollen), with sizes of the order of one thousandth of a millimeter—whereas atoms themselves are unobservable under a microscope since their size is considerably smaller at about 10 billionths of a centimeter.
Special Theory of Relativity According to Newtonian mechanics, forces are responsible for acceleration. In the absence of forces all bodies continue to either be at rest or move at a constant speed along a straight line. Observers on which no forces are acting are called inertial observers.
Newton's dynamical laws are the same for all inertial observers. Clearly inertial observers moving with respect to each other do not agree on velocities. For instance, e