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

Putzie,” and caught him slicing off the incriminating legend, for fear of inadvertently leaving one on Professor Wigner’s desk. “What do you care what other people think?” she said again and again. She knew he prided himself on honesty and independence, and she held him to his own high standards. It became a touchstone of their relationship. She mailed him a penny postcard with a verse written across it: If you don’t like the things I do

My friend, I say, Pecans to you!

If I irate with pencils new

My bosom pal, Pecans to you!

…

If convention’s mask is borne in view

…

If deep inside sound notions brew

And from without you take your cue

My sorry friend, Pecans to you!

Her words struck home. Meanwhile she had nagging health worries: a lump seemed to come and go on her neck, and she developed uncomfortable, unexplained fevers. Her uncle, a physician, had her rub the lump with a nostrum cal ed omega oil. (This style of treatment had had its heyday a hundred years before.)

The day after his presentation to the physics col oquium in February, Richard went up to Cambridge for a meeting of the American Physical Society, and she took the train from New York to Boston’s South Station to join him. An old fraternity friend picked her up and they crossed the bridge to MIT, catching a ride on a horse-drawn junk wagon. They found Richard in the corridor of building 8, the physics building. He walked by in animated conversation with a professor. Arline made eye contact with him, but he did not acknowledge her. She realized that it would be better not to speak.

When Richard returned to the fraternity house that evening he found her in the living room. He was ebul ient; he grabbed her and swung her around, dancing. “He certainly believes in physical society,” one of the fraternity boys said. At Wheeler’s prodding Feynman had presented their space-time electrodynamics a second time, to a broader audience. The talk went wel . After having faced a public of Einstein, Pauli, von Neumann, and Wigner, he had little to fear from the American Physical Society rank and

file. Stil , he worried that he might have bored his listeners by sticking nervously to his prepared text. There were a few polite questions, and Wheeler helped answer them.

Feynman had enunciated a set of principles for a theory of interacting particles. He wrote them out as fol ows: 1 The acceleration of a point charge is due only to the sum of its interactions with other charged particles…

. A charge does not act on itself.

2 The force of interaction which one charge exerts on a second is calculated by means of the Lorentz force formula, in which the fields are the fields generated by the first charge according to Maxwel ’s equations.

Phrasing the third principle was more difficult. He tried: 3 The fundamental equations are invariant with respect to a change of the sign of the time …

Then, more directly:

3 The fundamental (microscopic) phenomena in nature are symmetrical with respect to interchange of past and future.

Pauli, despite his skepticism, understood the power of the last principle. He pointed out to Feynman and Wheeler that Einstein himself had argued for an underlying symmetry of past and future in a little-known 1909 paper. Wheeler needed little encouragement; he made an appointment to cal at the white clapboard house at 112 Mercer Street.

Einstein received this pair of ambitious young physicists sympathetical y, as he did most scientists who visited in his last years. They were led into his study. He sat facing them behind his desk. Feynman was struck by how wel the reality matched the legend: a soft, nice man wearing shoes without socks and a sweater without a shirt. Einstein was wel known to be unhappy with the acausal paradoxes of quantum mechanics. He now spent much of his time writing screeds on world government which, from a less revered figure, would have been thought crackpot. His distaste for the new physics was turning him into, as he would have it,

“an obstinate heretic” and “a sort of petrified object, rendered blind and deaf by the years.” But the theory Wheeler and Feynman described was not yet a quantum theory—so far, it used only classical field equations, with none of the quantum-mechanical amendments that they knew would ultimately be necessary—and Einstein saw no paradox. He, too, he told them, had considered the problem of retarded and advanced waves. He reminisced about the strange little paper he had published in 1909, a manifesto of disagreement with a Swiss col eague, Walter Ritz. Ritz had declared that a proper field theory should include only retarded solutions, that the time-backward advanced

solutions

should

simply

be

declared

impermissible, innocent though the equations looked.

Einstein, however, could see no reason to rule out advanced waves. He argued that the explanation for the arrow of time could not be found in the basic equations, which truly were reversible.

On his bicycle in Far Rockaway.

Melville, Lucille, Richard, and Joan at the house they shared with Lucille's sister's family, at 14 New Broadway.

Richard and Arline : left , at Presbyterian Sanatorium.

At Los Alamos: “I opened the safes which contained behind them the entire secret of the atomic bomb…”

Slouching beside J. Robert Oppenheimer at a Los Alamos meeting: “He is by all odds the most brilliant young physicist here, and everyone knows this.”

Awaiting the Trinity test: “And we scientists are clever-too clever-care you not satisfied? Is four square miles in one bomb not enough? Men are still thinking. Just tell us how big you want it !”

I. I. Rabi (left) and Han s Bethe: Physicists are the Peter Pans of the human race, Rabi said.

At th e Shelter Island Conference , June 1947: Willis Lamb and John Wheeler , standing; Abraham Pais, Feynrnan, and Herman Feshbach, seated; Julian Schwinger, kneeling.

Jul ian Schwinger : “It seems to be the spirit of Macaulay which takes over, for he speaks in splendid periods, the carefully architected sentences rolling on, with every subordinate clause duly closing.”

Feynman and Hideki Yukawa in Kyoto, 1955 : Feynman presented his theory of superfluidity, the strange , frictionless behavior of liquid helium quantum mech anics writ large.

At Caltech , before a slide from his original presentation on antiparticles traveling backward through time.

Victor Weisskopf (left) and Freeman Dyson.

That was Feynman and Wheeler’s view. By insisting on the symmetry of past and future, they made the combination of retarded and advanced potentials seem a necessity. In the end, there was an asymmetry in the universe of their theory—the role of ordinary retarded fields far outweighs the backward advanced fields—but that asymmetry does not lie in the equations. It comes about because of the disordered, mixed-up nature of the surrounding absorber. A tendency toward disorder is the most universal

manifestation of time’s arrow. A movie showing a drop of ink diffusing in a glass of water looks wrong when run backward. Yet a movie showing the microscopic motion of any one ink molecule would look the same backward or forward. The random motions of each ink molecule can be reversed, but the overal diffusion cannot be. The system is microscopical y reversible, macroscopical y irreversible. It is a matter of chaos and probability. It is not impossible for the ink molecules, randomly drifting about, someday to reorganize themselves into a droplet. It is just hopelessly improbable. In Feynman and Wheeler’s universe, the same kind of improbability guaranteed the direction of time by ensuring disorder in the absorber. Feynman took pains to spel out the distinction in the twenty-two-page manuscript he wrote early in 1941: