Джеймс Глик - Genius - The Life and Science of Richard Feynman

Feynman insisted on cal ing them hygienic functions—and it required more plain, plodding arithmetic than either boy had ever encountered. Fortunately they had calculators, a new kind that replaced the old hand cranks with electric motors. Not only could the calculators add, multiply, and subtract; they could divide, though it took time. They would enter numbers by turning metal dials. They would turn on the motor and watch the dials spin toward zero. A bel would ring. The chug-chug-ding-ding rang in their ears for hours.

In their spare time Feynman and Welton used the same

machines to earn money through a Depression agency, the National Youth Administration, calculating the atomic lattices of crystals for a professor who wanted to publish reference tables. They worked out faster methods of running the calculator. And when they thought that they had their system perfected, they made another calculation: how long it would take to complete the job. The answer: seven years. They persuaded the professor to set the project aside.

Shop Men

MIT was stil an engineering school, and an engineering school in the heyday of mechanical ingenuity. There seemed no limit to the power of lathes and cams, motors and magnets, though just a half-generation later the onset of electronic miniaturization would show that there had been limits after al . The school’s laboratories, technical classes, and machine shops gave undergraduates a playground like none other in the world. When Feynman took a laboratory course, the instructor was Harold Edgerton, an inventor and tinkerer who soon became famous for his high-speed photographs, made with a stroboscope, a burst of light slicing time more finely than any mechanical shutter could. Edgerton extended human sight into the realm of the very fast just as microscopes and telescopes were bringing into view the smal and the large.

In his MIT workshop he made pictures of bul ets splitting

apples and cards; of flying hummingbirds and splashing milk drops; of golf bal s at the moment of impact, deformed to an ovoid shape that the eye had never witnessed. The stroboscope showed how much had been unseen. “Al I’ve done is take God Almighty’s lighting and put it in a container,” he said. Edgerton and his col eagues gave body to the ideal of the scientist as a permanent child, finding ever more ingenious ways of taking the world apart to see what was inside.

That was an American technical education. In Germany a young would-be theorist could spend his days hiking around alpine lakes in smal groups, playing chamber music and arguing philosophy with an earnest Magic Mountain volubility. Heisenberg, whose name would come to stand for the twentieth century’s most famous kind of uncertainty, grew enraptured as a young student with his own “utter certainty” that nature expressed a deep Platonic order. The strains of Bach’s D Minor Chaconne, the moonlit landscapes visible through the mists, the atom’s hidden structure in space and time—al seemed as one.

Heisenberg had joined the youth movement that formed in Munich after the trauma of World War I, and the conversation roamed freely: Did the fate of Germany matter

“more than that of al mankind”? Can human perception ever penetrate the atom deeply enough to see why a carbon atom bonds with two but never three oxygen atoms?

Does youth have “the right to fashion life according to its own values”? For such students philosophy came first in physics. The search for meaning, the search for purpose,

led natural y down into the world of atoms.

Students entering the laboratories and machine shops at MIT left the search for meaning outside. Boys tested their manhood there, learning to handle the lathes and talk with the muscular authority that seemed to emanate from the

“shop men.” Feynman wanted to be a shop man but felt he was a faker among these experts, so easy with their tools and their working-class talk, their ties tucked in their belts to avoid catching in the chuck. When Feynman tried to machine metal it never came out quite right. His disks were not quite flat. His holes were too big. His wheels wobbled.

Yet he understood these gadgets and he savored smal triumphs. Once a machinist who had often teased him was struggling to center a heavy disk of brass in his lathe. He had it spinning against a position gauge, with a needle that jerked with each revolution of the off-kilter disk. The machinist could not see how to center the disk and stop the tick-tick-tick of the needle. He was trying to mark the point where the disk stuck out farthest by lowering a piece of chalk as slowly as he could toward the spinning edge. The lopsidedness was too subtle; it was impossible to hold the chalk steady enough to hit just the right spot. Feynman had an idea. He took the chalk and held it lightly above the disk, gently shaking his hand up and down in time with the rhythm of the shaking needle. The bulge of the disk was invisible, but the rhythm wasn’t. He had to ask the machinist which way the needle went when the bulge was up, but he got the timing just right. He watched the needle, said to himself, rhythm , and made his mark. With a tap of the machinist’s

rhythm , and made his mark. With a tap of the machinist’s mal et on Feynman’s mark, the disk was centered.

The machinery of experimental physics was just beginning to move beyond the capabilities of a few men in a shop. In Rome, as the 1930s began, Enrico Fermi made his own tiny radiation counters from lipstick-size aluminum tubes at his institute above the Via Panisperna. He methodical y brought one element after another into contact with free neutrons streaming from samples of radioactive radon. By his hands were created a succession of new radioactive isotopes, substances never seen in nature, some with half-lives so short that Fermi had to race his samples down the corridor to test them before they decayed to immeasurability. He found a nameless new element heavier than any found in nature. By hand he placed lead barriers across the neutron stream, and then, in a moment of mysterious inspiration, he tried a barrier of paraffin. Something in paraffin—hydrogen?—seemed to slow the neutrons. Unexpectedly, the slow neutrons had a far more powerful effect on some of the bombarded elements. Because the neutrons were electrical y neutral, they floated transparently through the knots of electric charge around the target atoms. At speeds barely faster than a batted basebal they had more time to work nuclear havoc. As Fermi tried to understand this, it seemed to him that the essence of the process was a kind of diffusion, analogous to the slow invasion of the stil air of a room by the scent of perfume. He imagined the path they must be taking through the paraffin, col iding one, two, three, a hundred times with atoms of hydrogen, losing energy with

hundred times with atoms of hydrogen, losing energy with each col ision, bouncing this way and that according to laws of probability.

The neutron, the chargeless particle in the atom’s core, had not even been discovered until 1932. Until then physicists supposed that the nucleus was a mixture of electrical y negative and positive particles, electrons and protons. The evidence taken from ordinary chemical and electrical experiments shed little light on the nucleus.

Physicists knew only that this core contained nearly al the atom’s mass and whatever positive charge was needed to balance the outer electrons. It was the electrons—floating or whirling in their shel s, orbits, or clouds—that seemed to matter in chemistry. Only by bombarding substances with particles and measuring the particles’ deflection could scientists begin to penetrate the nucleus. They also began to split it. By the spring of 1938 not just dozens but hundreds of physics professors and students were at least glancingly aware of the ideas leading toward the creation of heavy new elements and the potential release of nuclear energies. MIT decided to offer a graduate seminar on the theory of nuclear structure, to be taught by Morse and a col eague.