| The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
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Counterpoints in science The Einstein Miracles The year 2005 marks the centenary of Albert Einstein's annus mirabilis (miracle year). That was the year the 26-year-old physicist proved that atoms are real, assembled the foundations of quantum physics, and changed our concepts of space, time, and motion with E=mc2, the world's most famous equation. As a result, Einstein is recognized by physicists as the most important scientific figure of the twentieth century. To this day, Einstein's name and theories still carry a magical quality even for those who have little idea of what it was he discovered. One of the great unsolved questions Einstein tackled at the turn of the century was whether molecules were real or only a bookkeeping device to explain chemical reactions. In an attempt to quantify the existence of molecules, Einstein tested the concept of Brownian motion. Brownian motionthe random movement of microscopic particles suspended in a liquid or gas' had been observed for more than a century. When you look through a microscope at tiny particles like pollen in a liquid like water, the particles jiggle around, and no one understood why. Einstein proved mathematically that Brownian motion was due to the particles colliding with the water molecules and calculated how many molecules were present in the solution. Einstein also changed the way we think about light. When light falls on certain metals, they eject electrons. Einstein explained the phenomenon by assuming that light consists of particles, or quanta (now called photons), rather than being purely a wave phenomenon as was previously thought. This work was the seed of quantum mechanics, which dominated twentieth-century physics and provided an understanding of atoms and the fundamental constituents of matter. Despite his monumental contribution to this new field of study, Einstein rejected his quantum brainchild and its accompanying uncertainties. In quantum mechanics, one can only describe the probabilities of various outcomes. Einstein believed in "causality"-that if one knew enough about the present one could predict the future precisely. "I do not believe that God plays dice," he said. Prior to Einstein, scientists thought light was broadcast through a medium they called the ether, just as sound is transmitted through air. Ether was assumed to fill all of space in the same way that air fills a room. It was believed that the motion of the earth through the ether should create an "ether wind," just as a hand moving through the air creates a current. Hypothetically, light beams headed in the same direction as Earth should be carried along faster than light headed in other directions. In 1887, American physicists Michelson and Morley went looking for the ether by clocking light headed in different directions. But whichever direction they measured it from, the velocity always came out the same. While the rest of the scientific world puzzled over these measurements, Einstein used them to create a radical new view of the universe-his theory of relativity. If Michelson and Morley were right, Einstein realized, then one of physics' founding fathers was very, very wrong. Two centuries earlier, Sir Isaac Newton had stated that space was not only a fixed and infinite grid, but also that time was absolute, as if kept by a divine stopwatch. But if the velocity of light was constant, Einstein found, then time had to be relative. His "special theory of relativity" proved time is relative to the speed one is traveling at; five minutes to someone streaking by at thousands of miles an hour might be a lifetime to someone crawling at the speed of a turtle. In this, Einstein was following in the footsteps of another great scientist, Isaac Newton. The two are often compared today. Newton's annus mirabilis was 1665, when he invented the calculus, explained how gravity works, discovered that white light contains the colors of the rainbow, and worked out the laws of motion. No one thought this brilliance could ever be equaled. Newton conceived of a universe based on gravitational force. All matter in the universe-the stars, the planets, even you and me-attracts other matter, and this explains the motions of heavenly bodies, the seasons, night and day, the tides, and why Australians do not go flying off into space. Einstein's theory of gravitation, presented to the world in 1915, went a step further. Einstein disputed Newton's theory, arguing that gravity was not a force but rather a warping of space-time. Instead of bodies being attracted to one another, Einstein envisioned a curved universe whose shape is dependent on the distribution of mass within it. Imagine space as a stretched trampoline. When something heavy—such as a dumbbell—is placed in the center of the trampoline, it dips. If you try to roll a ball along the surface, the ball will roll towards the center. Einstein imagined gravity working the same way, with spacetime acting as the trampoline and matter playing the role of the dumbbell. Which man was right? At the time, it was difficult to tell. The differences between each theory's predicted effects on the observable universe were so tiny that even Einstein had a hard time thinking of the right experiment. Einstein thought that measurements of starlight during an eclipse might do the trick. Gravitation according to Newton predicts that starlight passing by the sun should be deflected by 0.87 seconds of arc—one arc-second being equivalent to the diameter of a dime viewed from a mile away. According to Einstein, the deflection should be exactly twice the Newtonian value. Arthur Eddington, an eminent astronomer at Cambridge University, put the theories to the test by observing a total eclipse of the sun on Principé Island. On November 6, 1919, Edding-ton announced his results at a joint meeting of the Royal Society of London and the Royal Astronomical Society, beneath a portrait of Newton. World War I had just ended, and chauvinism was running high. Not many in that room were rooting for the German Jewish challenger of the British icon. Eddington solemnly announced that he had found exactly the deflection Einstein predicted. Legend has it that at a press conference later, a reporter asked the self-assured Eddington whether it was true that only three people in the world understood Einstein's theory. Eddington is supposed to have responded, "Who is the third?" The next day the London Times broke the story about Newton's overthrow, and the Einstein legend began. He became a world-famous figure, and everywhere he went, mobs turned out to see and hear him. Einstein said he wanted to know how God created the universe. Though he did not believe in a God who directly interferes in the affairs of men, he referred affectionately to Der Alte (the Old One) as the wise mentor whose thoughts and works he was trying to comprehend. When someone reported measurements—later proven wrong—that the velocity of light was not constant after all, Einstein dismissed the report with the comment, "God is subtle but he is not malicious." And while Eddington was studying the eclipse, a student asked him what he would do if the results did not support his gravitation theory. He replied, "I would feel sorry for dear old God. My theory is correct." All his scientific life, Einstein was driven by a powerful desire to describe space, time, matter, energy, and forces such as electromagnetism with a single theory. He once said that the longing to behold such harmony is like that of a religious devotee or a person in love. He did succeed in unifying space and time, mass and energy, gravitation and inertia. He failed, however, in his attempts to unite gravitation and electromagnetism. No one since has succeeded in creating a unified theory either. Einstein seems to have been born with an innate interest in science. By his own account, Einstein experienced two miracles during his childhood in Ulm, Germany. When he was four, his father showed him a compass. At the thought that some mysterious force lay hidden behind commonplace objects, he trembled and grew cold. At age twelve he had similar feelings after he was given a small book on Euclidean geometry. He referred to it as his holy book. From age 12 to 16 he taught himself calculus. Einstein studied physics in Zurich but after graduation could not find a university job. He went to work for the patent office in Bern instead. This gave him plenty of time to think about the most major problems in physics, which had gathered like storm clouds at the turn of the nineteenth century. In 1903, he married Mileva Maric, a Serbian fellow student of physics. He and Mileva had two sons, but the marriage was not a happy one. In 1919 he asked for a divorce, which she bitterly resisted. She demanded as a condition that he promise to give her his Nobel Prize money when and if he received that honor. When the prize came to him in 1921, he promptly turned the award money over to his ex-wife. Albert and Elsa Einstein Lowenthal, his cousin, were married June 2, 1919 in Berlin, where he was then a professor. Unlike the bohemian Einstein, who cared very little about money, clothes, or possessions, she was thoroughly middle class. According to Einstein's friend Charlie Chaplin, "She frankly enjoyed being the wife of the great man and made no attempt to hide the fact." Another friend commented that Einstein seemed out of place in the midst of the beautiful furniture, carpets, and paintings Elsa had assembled. Einstein was not as fortunate in love as in physics. On the death of his lifelong friend Michele Besso, he wrote, "What I most admired in him as a human being is the fact that he managed to live for many years not only in peace but also in lasting harmony with a woman—an undertaking in which I twice failed disgracefully." In December 1932, after the rise of Hitler, Einstein left Berlin for America. He was offered a position at the newly established Institute for Advanced Study in Princeton, where he remained for the rest of his life. Though a lifelong pacifist, he sent Roosevelt the letter which initiated the creation of the atomic bomb. He didn't want German physicists, working under Heisenberg, to invent it first. When he spoke out against the rise of McCarthyism after the war (it reminded him of the early days of the Nazis), several congressmen wanted to take away his American citizenship. Just after Einstein died in 1955, a spectacular cascade of discoveries in astronomy further verified his ideas: radio and X-ray sources, quasars, cosmic microwave background radiation, pulsars, black holes, and the accelerated expansion of the universe. Nowadays, Einstein's ghost presides over many astrophysics seminars that mull over new data streaming in from observatories and satellites. George Bernard Shaw aptly called Einstein "a maker of universes," but Einstein never took himself as seriously as others did. The famous picture of him licking an ice cream cone, eyes bright and an aureole of gray hair framing his visage, depicts the counterpoint between his childish delight in ordinary things and his world-changing intelligence. Sometimes Princeton high school students would phone his listed home number to get help with their math homework, and he would oblige. It's reported he was once asked to solve a difficult problem and responded, "I'm no Einstein!" A century after his miracle year, we live in a universe of science that Albert Einstein more than any other man constructed. The light of his intellect continues to shine in molecules too small to see and galaxies beyond the range of human sight or comprehension. Jerold M. Lowenstein is professor of medicine at the University of California, San Francisco. jlowen@itsa.ucsf.edu |