B003CTEFLQ EBOK

by Michio Kaku

  Two decades later, in 1682, all of London was terrified and amazed by a brilliant comet that was lighting up the night sky. Newton carefully tracked the motion of the comet with a reflecting telescope (one of his inventions) and found that its motion fit his equations perfectly if it was assumed to be in free fall and acted on by gravity. With the amateur astronomer Edmund Halley, he could predict precisely when the comet (later known as Halley’s comet) would return, the first prediction made on the motion of comets. The laws of gravity that Newton used to calculate the motion of Halley’s comet and the moon are the same ones NASA uses today to guide its space probes with breathtaking accuracy past Uranus and Neptune.

  According to Newton, these forces act instantaneously. For example, if the sun were to suddenly disappear, Newton believed the earth would be instantly thrown out of its orbit and would freeze in deep space. Everyone in the universe would know that the sun had just disappeared at that precise instant of time. Thus, it’s possible to synchronize all watches so they beat uniformly anywhere in the universe. A second on Earth has the same length as a second on Mars and Jupiter. Like time, space is also absolute. Meter sticks on Earth have the same length as meter sticks on Mars and Jupiter. Meter sticks do not change in length anywhere in the universe. Seconds and meters are therefore the same no matter where we journey in space.

  Newton thus based his ideas on the commonsense notion of absolute space and time. To Newton, space and time formed an absolute reference frame against which we can judge the motion of all objects. If we are traveling on a train, for example, we believe that the train is moving and the earth is still. However, after gazing at the trees passing our windows, we can speculate that perhaps the train is actually at rest, and the trees are being sent past our windows. Since everything in the train seems motionless, we can ask the question, which is really moving, the train or the trees? To Newton, this absolute reference frame could determine the answer.

  Newton’s laws remained the foundation for physics for nearly two centuries. Then, in the late nineteenth century, as new inventions such as the telegraph and the light bulb were revolutionizing the great cities of Europe, the study of electricity brought about a whole new concept in science. To explain the mysterious forces of electricity and magnetism, James Clerk Maxwell, a Scottish physicist at Cambridge University working in the 1860s, developed a theory of light not based on Newtonian forces, but on a new concept called fields. Einstein wrote that the field concept “is the most profound and the most fruitful that physics has experienced since Newton.”

  These fields can be visualized by sprinkling iron filings over a sheet of paper. Place a magnet beneath the sheet of paper, and the filings will magically rearrange themselves into a spider web–like pattern, with lines spreading from the North Pole to the South Pole. Surrounding any magnet, therefore, is a magnetic field, an invisible array of lines of force penetrating all of space.

  Electricity creates fields as well. At science fairs, children laugh when their hairs stand on end as they touch a source of static electricity. The hairs trace out the invisible electric field lines emanating from the source.

  These fields, however, are quite different from the forces introduced by Newton. Forces, said Newton, act instantly over all space, so that a disturbance in one part of the universe would be felt instantly throughout all the universe. Maxwell’s brilliant observation was that magnetic and electric effects do not travel instantaneously, like Newtonian forces, but take time and move at a definite velocity. His biographer Martin Goldman writes, “The idea of the time of magnetic action…seems to have struck Maxwell like a bolt out of the blue.” Maxwell showed, for example, that if one shook a magnet, it would take time for nearby iron filings to move.

  Imagine a spider web vibrating in the wind. A disturbance like the wind on one part of the web causes a ripple that spreads throughout the entire web. Fields and spider webs, unlike forces, allow for vibrations that travel at a definite speed. Maxwell then set out to calculate the speed of these magnetic and electric effects. In one of the greatest breakthroughs of the nineteenth century, he used this idea to solve the mystery of light.

  Maxwell knew from the earlier work of Michael Faraday and others that a moving magnetic field can create an electric field, and vice versa. The generators and motors that electrify our world are direct consequences of this dialectic. (This principle is used to light up our homes. For example, in a dam, falling water spins a wheel, which in turn spins a magnet. The moving magnetic field pushes the electrons in a wire, which then travel in a high-voltage wire to the wall sockets in our living rooms. Similarly, in an electric vacuum cleaner, the electricity flowing from our wall sockets creates a magnetic field that forces the blades of the motor to spin.)

  The genius of Maxwell was to put the two effects together. If a changing magnetic field can create an electric field and vice versa, then perhaps both of them can form a cyclical motion, with electric fields and magnetic fields continually feeding off each other and turning into each other. Maxwell quickly realized that this cyclical pattern would create a moving train of electric and magnetic fields, all vibrating in unison, each turning into the other in a never-ending wave. Then he calculated the speed of this wave.

  To his astonishment, he found that it was the speed of light. Further, in perhaps the most revolutionary statement of the nineteenth century, he claimed that this was light. Maxwell then announced prophetically to his colleagues, “We can scarcely avoid the conclusion that light consists of the transverse undulations of the same medium which is the cause of electric and magnetic phenomenon.” After puzzling over the nature of light for millennia, scientists finally understood its deepest secrets. Unlike Newton’s forces, which were instantaneous, these fields traveled at a definite speed: the speed of light.

  Maxwell’s work was codified in eight difficult partial differential equations (known as “Maxwell’s equations”), which every electrical engineer and physicist has had to memorize for the past century and a half. (Today, one can buy a T-shirt containing all eight equations in their full glory. The T-shirt prefaces the equations by stating, “In the beginning, God said…,” and ends by saying, “…and there was light.”)

  By the end of the nineteenth century, so great were the experimental successes of Newton and Maxwell that some physicists confidently predicted that these two great pillars of science had answered all the basic questions of the universe. When Max Planck (founder of the quantum theory) asked his advisor about becoming a physicist, he was told to switch fields because physics was basically finished. There was nothing really new to be discovered, he was told. These thoughts were echoed by the great nineteenth-century physicist Lord Kelvin, who proclaimed that physics was essentially complete, except for a few minor “clouds” on the horizon that could not be explained.

  But the deficiencies of the Newtonian world were becoming more and more glaring each year. Discoveries like Marie Curie’s isolation of radium and radioactivity were rocking the world of science and catching the public imagination. Even a few ounces of this rare, luminous substance could somehow light up a darkened room. She also showed that seemingly unlimited quantities of energy could come from an unknown source deep inside the atom, in defiance of the law of conservation of energy, which states that energy cannot be created or destroyed. These small “clouds,” however, would soon spawn the great twin revolutions of the twentieth century, relativity and the quantum theory

  But what seemed most embarrassing was that any attempt to merge Newtonian mechanics with Maxwell’s theory failed. Maxwell’s theory confirmed the fact that light was a wave, but this left open the question, what is waving? Scientists knew that light can travel in a vacuum (in fact traveling millions of light-years from distant stars through the vacuum of outer space), but since a vacuum by definition is “nothing,” this left the paradox that nothing was waving!

  Newtonian physicists tried to answer this question by postulating that light consisted of waves vibrat
ing in an invisible “aether,” a stationary gas that filled up the universe. The aether was supposed to be the absolute reference frame upon which one could measure all velocities. A skeptic might say that since the earth moved around the sun, and the sun moved around the galaxy, then it was impossible to tell which was really moving. Newtonian physicists answered this by stating that the solar system was moving with respect to the stationary aether, so one could determine which was really moving.

  However, the aether began to assume more and more magical and bizarre properties. For example, physicists knew that waves travel faster in a denser medium. Thus, sound vibrations can travel faster in water than in air. However, since light traveled at a fantastic velocity (186,000 miles per second), it meant that the aether must be incredibly dense to transmit light. But how could this be, since the aether was also supposed to be lighter than air? With time, the aether became almost a mystical substance: it was absolutely stationary, weightless, invisible, with zero viscosity, yet stronger than steel and undetectable by any instrument.

  By 1900, the deficiencies of Newtonian mechanics were becoming harder and harder to explain. The world was now ready for a revolution, but who would lead it? Although other physicists were well aware of the holes in the aether theory, they timidly tried to patch them up within a Newtonian framework. Einstein, with nothing to lose, was able to strike at the heart of the problem: that Newton’s forces and Maxwell’s fields were incompatible. One of the two pillars of science must fall. When one of these pillars finally fell, it would overturn more than two hundred years of physics and would revolutionize the way we view the universe and reality itself. Newtonian physics would be toppled by Einstein with a picture that even a child could understand.

  CHAPTER 2

  The Early Years

  The man who would forever reshape our conception of the universe was born on March 14, 1879, in the small city of Ulm, Germany. Hermann and Pauline Koch Einstein were distressed that their son’s head was misshapen, and prayed that he was not mentally damaged.

  Einstein’s parents were middle-class secularized Jews struggling to provide for their growing family. Pauline was the daughter of a relatively wealthy man: her father, Julius Derzbacher (who changed his name to Koch), established his fortune by leaving his job as a baker and entering the grain trade. Pauline was the cultured one in the Einstein family, insisting that her children take up music and starting young Albert on his lifelong love affair with the violin. Hermann Einstein, in contrast to his father-in-law, had a lackluster business career, originally starting in the featherbed business. His brother Jakob convinced him to switch to the new electrochemical industry. The inventions of Faraday, Maxwell, and Thomas Edison, all of which harnessed the power of electricity, were now lighting up cities around the world, and Hermann saw a future building dynamos and electric lighting. The business would prove precarious, however, leading to periodic financial crises and bankruptcies and forcing the family to relocate several times during Albert’s childhood, including to Munich a year after his birth.

  The young Einstein was late in learning how to speak, so late that his parents feared that he might be retarded. But when he finally did speak, he did so in complete sentences. Still, even as a nine-year-old, he could not talk very well. His only sibling was his sister Maja, two years younger than Albert. (At first, young Albert was puzzled by the new presence in the household. One of his first phrases was, “But where are the wheels?”) Being the younger sister to Albert was no joy, since he had a nasty tendency to throw objects at her head. She would later lament, “A sound skull is needed to be the sister of a thinker.”

  Contrary to myth, Einstein was a good student in school, but he was only good in the areas he cared about, such as mathematics and science. The German school system encouraged students to give short answers based on rote memorization—otherwise, they might be punished by painful slaps to the knuckles. Young Albert, however, spoke slowly, hesitantly, choosing his words carefully. He was far from being the perfect student, chafing under a suffocating, authoritative system that crushed creativity and imagination, replacing them with mind-numbing drills. When his father asked the headmaster what profession young Albert should pursue, he replied, “It doesn’t matter; he’ll never make a success of anything.”

  Einstein’s demeanor established itself early. He was dreamy, often lost in thought or reading. His classmates used to taunt him by calling him Biedermeier, which translates loosely as “nerd.” A friend would remember, “Classmates regarded Albert as a freak because he showed no interest in sports. Teachers thought him dull-witted because of his failure to learn by rote and his strange behavior.” At age ten, Albert entered the Luitpold Gymnasium in Munich, where his most excruciating ordeal was learning classical Greek. He would sit in his chair, smiling blankly to hide his boredom. At one point his seventh-grade Greek teacher, Herr Joseph Degenhart, told Albert to his face that it would be better if he simply were not there. When Einstein protested that he did nothing wrong, the teacher replied bluntly, “Yes, that is true. But you sit there in the back row and smile, and that violates the feeling of respect which a teacher needs from his class.”

  Even decades later, Einstein would bitterly nurse the scars left by the authoritarian methods of the day: “It is, in fact, nothing short of a miracle that the modern methods of instruction have not yet entirely strangled the holy curiosity of inquiry; for this delicate little plant, aside from stimulations, stands mainly in need of freedom.”

  Einstein’s interest in science started early, beginning with his encounter with magnetism, which he called his “first miracle.” He was given a compass by his father and was endlessly fascinated by the fact that invisible forces could make objects move. He fondly remembered, “A wonder of such nature I experienced as a child of 4 or 5 years, when my father showed me a compass needle…. I can still remember…that this experience made a deep and lasting impression upon me. Something deeply hidden had to be behind things.”

  When he was about eleven, however, his life took an unexpected turn: he became devoutly religious. A distant relative would come by to tutor Albert in the Jewish faith, and he latched onto it in a surprisingly enthusiastic, almost fanatical way. He refused to eat pork and even composed several songs in praise of God, which he sang on his way to school. This period of intense religious fervor did not last long, however. The further he delved into religious lore and doctrine, the more he realized that the worlds of science and religion collided, with many of the miracles found in religious texts violating the laws of science. “Through the reading of popular books I soon reached the conviction that much in the stories of the Bible could not be true,” he concluded.

  Just as abruptly as he picked religion up, he dropped it. His religious phase, however, would have a profound effect on his later views. His reversal represented his first rejection of unthinking authority, one of the lifelong hallmarks of his personality. Never again would Einstein unquestioningly accept authority figures as the final word. Although he concluded that one could not reconcile the religious lore found in the Bible with science, he also decided that the universe contained whole realms that were just beyond the reach of science, and that one should have profound appreciation for the limitations of science and human thought.

  His early interest in compasses, science, and religion, however, might have withered had young Albert not found a caring mentor to hone his ideas. In 1889, a poor Polish medical student named Max Talmud was studying in Munich and ate weekly dinners at the Einstein house. It was Talmud who introduced Einstein to the wonders of science beyond the dry, rote memorization of his classes. Years later, Talmud would fondly write, “In all these years I never saw him reading any light literature. Nor did I ever see him in the company of school mates or other boys of his age. His only diversion was music, he already played Mozart and Beethoven sonatas, accompanied by his mother.” Talmud gave Einstein a book on geometry, which he devoured day and night. Einstein called this his “
second miracle.” He would write, “At the age of 12, I experienced a second wonder of a totally different nature: in a little book with Euclidean plane geometry.” He called it his “holy geometry book,” which he treated as his new Bible.

  Here at last, Einstein made contact with the realm of pure thought. Without expensive laboratories or equipment, he could explore universal truth, limited only by the power of the human mind. Mathematics, observed his sister Maja, became an endless source of pleasure to Albert, especially if intriguing puzzles and mysteries were involved. He bragged to his sister that he had found an independent proof of the Pythagorean theorem about right triangles.

  Einstein’s mathematical readings did not stop there; eventually he taught himself calculus, surprising his tutor. Talmud would admit, “Soon the flight of his mathematical genius was so high that I could no longer follow…. Thereafter, philosophy was often the subject of our conversations. I recommended that he read Kant.” Talmud’s exposure of young Albert to the world of Immanuel Kant and his Critique of Pure Reason nourished Einstein’s lifelong interest in philosophy. He began to ponder the eternal questions facing all philosophers, such as the origin of ethics, the existence of God, and the nature of wars. Kant, in particular, held unorthodox views, even casting doubt about the existence of God. He poked fun at the pompous world of classical philosophy, where “there is usually a great deal of wind.” (Or, as the Roman orator Cicero once said, “There is nothing so absurd that it has not been said by a philosopher.”) Kant also wrote that world government was the way to end wars, a position that Einstein would hold for the rest of his life. At one point, Einstein was so moved by the musings of Kant that he even considered becoming a philosopher. His father, who wanted a more practical profession for his son, dismissed this as “philosophical nonsense.”