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LIGHT YEAR

What Einstein Did in 1905

12:00 AM, Oct 5, 1998 • By JONATHAN V. LAST
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Young men and women start out believing in giants -- not make-believe giants, mind you, but real, hulking gargantuans who only rarely notice the mortals flitting about them. For someone just starting out on adult life, the world seems full of actual giants, legendary figures who have lived lives and filled careers far beyond any normal person's capacity.


Then one day, with a dull thump, we realize that our heroes weren't all that different from other human beings. They remain admirable -- smarter or faster than we are, stronger or harder working -- but they no longer seem the incomparable, inhuman figures of our youth.


What we sometimes forget, however, as our heroes shrink back down to human dimensions, is that there are a thimbleful of people who really were giants, who will not ever shrink. Shakespeare, Leonardo da Vinci, and Isaac Newton were not real people any more than Atlas was. And among this select cadre -- maybe a few hundred of the ten billion people who have ever lived -- only one has walked among us in the last hundred years: Albert Einstein.


Einstein was simply not made of the same material as everyone else. One way to be convinced of his unearthly genius is to read Einstein's Miraculous Year: Five Papers That Changed the Face of Physics, a slim volume edited by the scholar John Stachel. Stachel reproduces Einstein's five famous papers from 1905 and gives a brief, intelligent explanation of each. The result is an over-powering testament to Einstein's greatness.


The intellectual paparazzi have done their best in the last ten years to diminish Einstein. After his death in 1955, his friend Otto Nathan and secretary Helen Dukas kept most of Einstein's personal papers out of public reach. But in 1987, after a protracted legal battle, the Einstein archives were opened, and the result was biographies like Denis Brian's Einstein: A Life, a cheap expose that sensationalized his relations with women and alleges an illegitimate daughter.


The important details of Einstein's life are well known. Born on March 14, 1879, in Ulm, Germany, the young Einstein was thought by some to be slow. He struggled in school subjects that didn't interest him, like Greek, and dropped out of high school in order to avoid Germany's year of compulsory military service. He was rejected from Zurich Polytechnic after failing the French, biology, and chemistry sections of the entrance exam.


But the signs of his true abilities were evident from the beginning. When he was a child he asked his parents what the world would look like if he were riding away from it on a beam of light (the answer, as he would be the first to determine, is that everything would look exactly as it had when you began moving because you would be traveling at the same speed as all of those images). At twelve he was so taken with Euclidean geometry that he called it "holy." At sixteen he wrote an essay that contained the seeds of his theory of special relativity.


And then, in 1905, at the age of twenty-six, Einstein had his annus mirabilis, the greatest year in science since the "Year of Wonders," 1666, when a twenty-four-year-old Isaac Newton codified all of classical physics. In this one year, Einstein wrote five papers, each of which could have been the culmination of a life's work for any mortal scientist.


His first paper, "A New Determination of Molecular Dimensions," proposed a method for determining molecular size. At the time, the existence of atoms and molecules was in itself in some dispute, and the only way to find the physical size of molecules was by using the kinetic theory of gases. But what about molecules that couldn't be found in gaseous form? Einstein proved that by dissolving a substance in a liquid and measuring the varying viscosity of the resulting solutions, atomic size could be very closely approximated.


In his second paper, "On the Motion of Small Particles Suspended in Liquids at Rest Required by the Molecular-Kinetic Theory of Heat," Einstein addressed the problem of determining the sizes of molecules that could be neither made gaseous nor dissolved. After suspending these materials in a liquid and observing the Brownian Motion of the suspended particles, one could determine their size by measuring the mean-square displacement.


Papers three and four -- "On the Electrodynamics of Moving Bodies" and "Does the Inertia of a Body Depend on Its Energy Content?" -- dealt with Einstein's first truly revolutionary observations: that the speed of light is absolute and that physics centers around the precept of special relativity. His final paper, "On a Heuristic Point of View Concerning the Production and Transformation of Light," cemented yet another revolutionary idea about light: that it travels in particles, or quanta.


Like all studies of elemental phenomena, the study of light began with observations. Light is so basic that early thinkers had no inkling of what it was, so they took note of how it behaved. Euclid developed a Law of Reflection; Hero of Alexandria, observing Euclid's work and evidence of the rectilinear propagation of light, proposed that light always travels the shortest distance between two points. Aristotle gave brief thought to how light might work and proposed a primitive method of conduction via the medium of a mysterious "aether," and his thought was refined by Rene Descartes in his "Law of Refraction." Descartes and others proposed that "the energy of a light ray emitted from a point source continuously spreads out over an ever increasing volume" and exhibits "a rapid vibratory motion of the medium propagating at a very great speed" -- which is to say that light is a wave.


Waves are physical disturbances, and in order to travel, they must have some substance to disturb. This presents no problem for light on Earth, where the air is made up of a complex mix of gasses. But it does create difficulties in the vacuum of space. And to get around these difficulties, scientists postulated the existence of an invisible, luminiferous aether permeating the universe and providing a medium through which waves of light may travel. Newton was suspicious of the notion of the aether and proposed briefly in his treatise on optics that light might be not a wave but a string of particles that needed no medium. But while his corpuscular theory held some sway for a while, the hypothesis of the aether carried the day. Indeed, it was an enormously helpful scientific hypothesis. It could support the fantastically high frequencies of light, yet allow planets to move through it unimpeded. It even established a universal clock by creating a single inertial frame of reference.


The descent into the aether represented one of physics' most notorious wrong turns since Ptolemy posited that the sun revolves around the earth. From the beginning there was evidence to the contrary, but for three centuries scientists put themselves through all manner of contortions to explain the aether.


In 1725, the astronomer James Bradley tried to triangulate the distance to a star by observing its position at two different times during the year. Bradley was shocked to find that the star appeared to move in the direction of Earth's orbit. But instead of drawing the obvious conclusion that the star's light was behaving like particles, Bradley decided that his work was proof that the aether not only was ubiquitous and invisible, but also had the amazing ability to remain wholly undisturbed as the planets moved through it.


More than 150 years after Bradley's work, Albert Michelson and Edward Morley attempted to measure the earth's motion through this aether. They reasoned that if the earth moves in relation to the aether (which it must since the aether is perpetually at rest), then the earth's motion should influence the speed of the light perceived on the earth. They found it did not.


The Michelson-Morley experiment should have rocked the world, but it was instead for the most part willfully ignored. A few scientists did begin to question the existence of the aether, but most concluded that the experiment itself must have been flawed in some way.


And so it fell to Einstein to fix the broken concepts of not only how light behaved, but what light was. Using the work of Hendrik Lorentz and James Maxwell, Einstein took as established that the speed of light was an absolute. He then began to think about the nature of simultaneous events.


Whether or not two things happen at "the same time" depends on the proximity of the events to the observer. If the events and the observer are all in the same frame of reference, then they may happen simultaneously. But if they are not all in the same frame of reference, the possibility of two events' happening "at the same time" becomes very difficult to hold.


Einstein still held one constant, the speed of light, which he labeled "c." But he made it a stricter constant than the scientific world had ever seen. Unlike anything else, light has an absolutely constant velocity. If a man is standing on a train moving twenty miles per hour and throws a baseball forward at thirty miles per hour, the baseball is actually moving fifty miles per hour. But if that man turns on a flashlight, the light moves at the same speed that it would if he were standing still. The speed of light never varies.


The concept of multiple frames of reference was utterly revolutionary. And when combined with the absolute speed of light, it led to the paper on the special theory of relativity, which Einstein wrote in five weeks, and later to his formula E=mc<2> -- the famous expression of the relation between the mass of an object and its energy.


Knowing the most important characteristic of light, Einstein turned to its nature. One of the most vexing problems of physics in the early 1900s was the mystery of the photoelectric effect. When light shines on certain metals, electrons are emitted. And worse yet for the wave theory, the number of electrons emitted increases with the intensity of the light, and the energy of the emitted electrons increases with the frequency of the light.


Einstein determined that the photoelectric effect must be the result of the bombardment of the metal by discrete packets of energy, which he dubbed "photons." The photon is a particle of light whose energy is proportional to its frequency and whose propagation requires no intermediary medium. This theory of quantum light was so radical that it was immediately dismissed by most of the scientific community as folly until 1916, when Robert Millikan confirmed Einstein's calculations about the photoelectric effect. By the early 1920s, at long last, the photon was accepted and quantum theory predominated.


After hundreds of years of wrong thinking, Einstein had abolished the aether. He did for light what Newton had done for gravity: In five papers in 1905, he gave it a thorough, original, and mathematically complete explanation and changed all our conceptions of the world and the boundaries of science.


All that work in one year's time. The rest of his life saw other accomplishments. In 1916, for example, he published what would become his most famous work, The General Theory of Relativity. But mostly, his remaining days were spent chasing the one that got away: the unified field theory.


When Einstein finally published his Unified Field Theory in 1929, he created a media circus. After submitting the paper to the Prussian Academy of Sciences, he retired to his home in Berlin. The academy, not knowing what to make of the six dense pages of equations, simply released the long-awaited work to the public without commenting on it. The new theory, which tried to find a single set of laws to govern both electricity and gravity, mystified literally everyone in the world, and hordes of reporters from around the globe camped outside Einstein's house for weeks, waiting for the great man to explain himself. Finally, Einstein granted his only interview to a reporter from the New York Times -- as a favor to its managing editor, Carr Van Anda, who had once corrected one of Einstein's mathematical mistakes. (Like many theoretical physicists and mathematicians, Einstein found actual calculation tedious, and occasional errors crop up in the math in his letters and notebooks.)


Einstein emigrated to the United States in 1933 after the Nazis confiscated all his property for the crimes of "cultural intellectualism, intellectual treason, and pacifist excesses." He took a position at Princeton University's Institute for Advanced Study, where he requested as his only research equipment "a desk or table, a chair, paper, and pencils. Oh yes, and a large waste basket . . . so I can throw away all my mistakes."


In the early months of World War II, aware of German experiments with fission, Einstein signed a letter (prepared by other physicists) describing to President Roosevelt the possibility of creating an atomic bomb, and his prestige was sufficient to spark the birth of the Manhattan Project. He was offered the prime minister's post in the newly born nation of Israel, but he turned it down so that he could continue working on the unified field theory that would, he hoped, lay bare God's blueprint for the universe.


He never succeeded, but without knowing it he sketched the task for the next three generations: super-string theory. In Einstein's time, physicists were aware of only two fundamental forces of physics, while today there are four known forces: gravitational, electromagnetic, weak atomic, and strong atomic. And today every theoretical physicist worth his salt, from Stephen Hawking to John Wheeler, is obsessed with the quest for unification of the laws that govern these forces.


That quest has recently taken a fascinating and mind-bending twist into the world of fundamental particles. In the fifteen years following Einstein's death in 1955, a number of very, very small particles were discovered -- and the theory of quarks was developed to explain them. According to quark theory, the only elementary particles are leptons and quarks (although there are six flavors of quarks, each of which comes in six colors). Leptons and quarks combine in various ways and combinations to make different, bigger particles, much as electrons, neutrons, and protons combine to make different types of atoms.


Superstring theory postulates that there is only one truly elemental particle, which is a tiny loop of "string" that measures roughly 10<-35> meters and has an incredibly high level of energy. This string vibrates in different ways, and it is these different modes of vibration that cause the string to take on the forms of the different leptons and quarks, which in turn serve as the building blocks for all other particles. If superstring theory were proved, it would not only establish a fundamental particle, but also solve Einstein's problem of the unified field theory.


The problem is that for superstring theory to hold, the strings themselves must exist in anywhere from six to twenty-two dimensions beyond the four we see in everyday life.


More, the combining of these strings would take place on a scale that is many orders of magnitude smaller than is measurable by any sort of technology we can build. Finding a way to refine and prove superstring theory and finish Einstein's unification will require advances so revolutionary that no one can imagine what they might be.


No one, that is, but a giant.




Jonathan V. Last is a reporter at THE WEEKLY STANDARD.