Quantum Man: Richard Feynman's Life in Science (5 page)

CHAPTER
3

A New Way of Thinking

An idea which looks completely paradoxical at first, if analyzed to completion in all its details and in experimental situations, may in fact not be paradoxical.

—R
ICHARD
F
EYNMAN

D
espite the assurances of Richard’s undergraduate professors, Melville Feynman did not lay his concerns about his son’s future to rest. After Richard had begun his working relationship with John Archibald Wheeler in graduate school, Melville made the trek to Princeton to check once more on his progress and prospects. Once again, he was told that Richard had a brilliant future ahead of him, independent of his “simple background” or possible “anti-Jewish prejudice,” as Melville phrased things. Wheeler may have been sugarcoating reality, or merely reflecting his own ecumenical bent. While still a student he had been the founder and president of the Federation of Church and Synagogue Youth.

Nevertheless, even any lingering anti-Semitism in academia would not have been sufficient to halt Richard Feynman’s march forward. He was simply too good and having too much fun. Only a fool would not recognize his genius and his potential. As they would continue to throughout his life, Feynman’s fascination with physics, and his ability to solve problems others couldn’t, stretched across the spectrum of the physical world, from the esoteric to the seemingly mundane.

Everywhere there were glimpses of his playful intensity. The Wheeler children used to love his visits, when he would often amuse them with tricks. Wheeler remembered one afternoon when Feynman asked for a tin can and told the children that he could tell whether solid or liquid was inside without even opening it or looking at the label. “How?” came a chorus of young voices. “By the way it turns when I toss it up in the air,” he answered, and sure enough, he was right.

Feynman’s own childlike excitement about the world meant that his popularity with children remained unabated, as reflected in a letter written in 1947 by the physicist Freeman Dyson, who was a graduate student at Cornell when Feynman was an assistant professor there. Describing a party at the home of the physicist Hans Bethe in honor of a distinguished visitor, Dyson remembered that Bethe’s five-year-old son, Henry, kept complaining that Feynman was not there, saying, “I want Dick. You told me Dick was coming.” Ultimately Feynman arrived, dashed upstairs, and then proceeded to play noisily with Henry, stopping all conversation down below.

Even as Feynman entertained Wheeler’s children, he and Wheeler continued to amuse each other as they worked throughout the year to explore their exotic ideas on ridding classical electromagnetism of the problem of infinite self-interaction of charged particles, via strange backward-in-time interactions with external absorbers located out in an infinite universe.

Feynman’s motivation for continuing this work was straightforward. He wanted to solve a mathematical problem in classical electromagnetism with the hope of ultimately addressing the more serious problems that arose in the quantum theory. Wheeler, on the other hand, had an even crazier notion he wanted to develop to explain the new particles that were being observed in cosmic rays and ultimately in nuclear physics experiments: maybe all elementary particles were just made of different combinations of electrons, somehow interacting differently with the outside world. The notion was crazy, but at least it helped maintain his own enthusiasm for the work they were doing.

Feynman’s own playful attitude toward the inevitable frustrations and stumbling blocks associated with theoretical work in physics is exemplified by one of the earliest letters he wrote his mother, shortly after starting graduate school and before his work with Wheeler had moved in the direction of reexamining electromagnetism:

Last week things were going fast and neat as all heck, but now I’m hitting some mathematical difficulties which I will either surmount, walk around, or go a different way—all of which consumes all my time—but I like to do very much and am very happy indeed. I have never thought so much so steadily about one problem—so if I get nowhere I really will be very disturbed—However, I have already gotten somewhere, quite far—and to Prof. Wheeler’s satisfaction. However, the problem is not at completion although I’m just beginning to see how far it is to the end and how we might get there (although aforementioned mathematical difficulties loom ahead)—SOME FUN!

Feynman’s idea of fun included prevailing over mathematical difficulties—one of the many attributes that probably separated him from the man on the street.

After an intense few months of give-and-take with Wheeler in the fall and winter of 1940–41 working on their new ideas for electromagnetism, Wheeler finally gave Feynman a chance to present these ideas, not to graduate students, but to professional physicists, through the Princeton physics department seminar. But this was not to be just any group of colleagues. Eugene Wigner, himself a later Nobel Prize winner, ran the seminar and invited, among others, a special cast of characters: the famous mathematician John von Neumann; the formidable Nobel Prize winner and one of the developers of quantum mechanics, Wolfgang Pauli, who was visiting from Zurich; and none other than Albert Einstein, who had expressed an interest in attending (perhaps egged on by contact with Wheeler).

I have tried to imagine myself in Feynman’s place, as a graduate student speaking among such a group. This would not be an easy crowd to please, independent of their eminence. Pauli, for example, was known to jump up and take the chalk out of the hands of speakers with whom he disagreed.

Feynman nevertheless prepared his talk and once he began, the physics took over and any residual nervousness disappeared. As expected, Pauli objected, concerned about whether the use of the backward-in-time reactions might have implied that one was simply working backward mathematically from the correct answer and not actually deriving anything new. He was also concerned about the “action-at-a-distance” aspect of the ideas, once one had dispensed with the fields that usually transport the forces and information, and he asked Einstein whether this might be incompatible with his own work on general relativity. Amusingly, Einstein humbly responded that there might be a conflict, but after all his own theory of gravitation (which the rest of the physics community has regarded as the most significant single piece of work since Newton) was “not so well established.” Actually, Einstein was sympathetic to the notion of using backward-in-time as well as forward-in-time solutions, as Wheeler later recalled, when he and Feynman went to visit Einstein at his Mercer Street home to talk further about their work.

The problem is that one of the most obvious features of the physical world, manifest from the moment we wake up each day, is that the future is different from the past. This is true not only for human experience, but also for the behavior of inanimate objects. When we put milk in our coffee and stir it, we will never see that milk at some point in the future coalesce into separate droplets like it appeared when we first poured it into the coffee. The question is: does this apparent temporal irreversibility in nature arise because of an asymmetry in microscopic processes, or is it only appropriate for the macroscopic world we experience?

Like Feynman and Wheeler, Einstein believed that the microscopic equations of physics should be independent of the arrow of time—namely, the apparent irreversibility of phenomena in the macroscopic world arises because certain configurations are far more likely to arise naturally when many particles are involved than are other configurations. In the case of Feynman and Wheeler’s ideas, as Feynman had shown to his fellow graduate student, physics behaved sensibly in the bulk—that is, the future was different from the past in spite of the weird backward-in-time interaction he and Wheeler included. This was precisely because the probabilities associated with the behavior of the rest of the presumably infinite number of other charges in the universe responding to the motion of the charge in question produced the kind of macroscopic irreversibility we are used to seeing in the world around us.

Later, in 1965, physicists discovered, much to their surprise, that certain microscopic processes for elementary particles do have an arrow of time associated with them—namely, the rates for a process and its time-reversed version are slightly different. This result was so surprising that it garnered the Nobel Prize for the experimentalists involved. Nevertheless, while this effect may play an important role in understanding certain features of our universe, including perhaps why we live in a universe of matter and not antimatter, conventional wisdom still suggests that the macroscopic arrow of time is associated with the tendency for disorder to increase, and arises, not from microscopic physics, but from macroscopic probabilities, as Einstein, Feynman, and Wheeler had presumed.

U
LTIMATELY ALL THIS
Sturm und Drang associated with the interpretation of Feynman and Wheeler’s ideas was misplaced. The theoretical ideas they had proposed ended up being more or less wrong, in that their proposals didn’t ultimately correspond to reality. Electrons do have self-interactions, and electromagnetic fields, including those involving virtual particles, are real. Feynman summed it up well a decade later when he wrote to Wheeler, “So I think we guessed wrong in 1941. Do you agree?” History has recorded no response from Wheeler, but by then the evidence was indisputable.

So what was the point of all of this work? Well, in science almost every significant new idea is wrong, either trivially wrong (there is a mathematical error) or more substantially wrong (as beautiful as the idea is, nature chooses not to exploit it). If that were not the case, then pushing the frontiers of science forward would be almost too easy.

In light of this, scientists have two choices. Either they can choose to follow well-trodden ground and push solid results a tad further with a reasonable assurance of success. Or they can strike out into new and dangerous territory, where there are no guarantees and they have to be prepared for failure. This might seem depressing, but in the process of exploring all the dead ends and blind alleys, scientists build up experience and intuition and a set of useful tools. Beyond this, unexpected ideas resulting from proposals that lead nowhere, at least as far as the original problem is concerned, nevertheless sometimes carry scientists in a direction that was completely unanticipated, and which every now and then can hold the key to progress. Sometimes ideas that don’t work in one area of science end up being just what was needed to break a lo
g
jam elsewhere. As we will see, so it was with Richard Feynman’s long journey through the wilderness of electrodynamics.

A
MID THE TURBULENT
intellectual flow in Feynman’s life during this period, his personal life evolved deeply as well. Ever since he had been a young man, a child almost, he had known, admired, and dreamed about a certain girl, a girl who possessed qualities that weren’t manifest in him: artistic and musical talents, and the social confidence and grace that often accompany them. Arline Greenbaum had become a presence in his life early on in high school. He had met her at a party when he was fifteen and she was thirteen. She must have had everything he was looking for. She played the piano, danced, and painted. By the time he had entered MIT, she had become a fixture in his family life, painting a parrot on the door of a clothes closet for the family, and teaching piano to his sister Joan and then taking her for walks afterward.

We will never know if these kindnesses were Arline’s way of ingratiating herself with Richard, but it was clear that she had decided he was the young man for her, and he too was smitten. Joan later claimed that by the time Richard entered MIT, when he was seventeen, the rest of the family knew that one day they would be married. They were right. Arline had visited him at his fraternity in Boston on weekends during his early years at college, and by the time he was a junior, he had proposed, and she had accepted.

Richard and Arline were soul mates. They were not clones of each other, but symbiotic opposites—each completed the other. Arline admired Richard’s obvious scientific brilliance, and Richard clearly adored the fact that she loved and understood things he could barely appreciate at that time. But what they shared, most important of all, was a love of life and a spirit of adventure.

Arline makes her way into this scientific biography at this point not merely because she was Feynman’s first, and perhaps deepest, love, but because her spirit provided him with the vital encouragement he needed to keep going, to find new roads, to break traditions, scientific and otherwise.

Their correspondence during the five years between the time of his proposal and her death from tuberculosis is remarkably touching and moving. Filled with naive hope, combined with mutual love and respect, they reflect two young people who were determined to make their own way in the world no matter what the obstacles.

In June of 1941, when Richard was well along in his graduate career, and a year before their marriage, Arline wrote to fill him in on her visits to doctors (it took many misdiagnoses before they eventually got her condition correct), but the letter focuses on him, not her:

Richard sweetheart I love you. . . . we still have a little more to learn in this game of life and chess—and I don’t want to have you sacrifice anything for me. . . . I know you must be working very hard trying to get your paper out—and do other problems on the side—I’m awfully happy tho’ that you’re going to publish something—it gives me a very special thrill when your work is acknowledged for its value—I want you to continue and really give the world and science all you can . . . and if you receive criticisms—remember everyone loves differently.

Arline knew Richard as no one else did, and in so doing she had the power both to embarrass him and to drive him forward to hold true to his beliefs. Most important among these were honesty and the courage to make his own choices. The title of one of his famous autobiographical books,
“What Do
You
Care What Other People Think?”
is the question she often repeated when she caught him in a timid or insecure moment, such as when she sent him a box of pencils, each engraved with the phrase “Richard darling, I love you! Putsie” (Putsie was his pet name for her), and caught him slicing off the words in case Professor Wheeler might see them when they were working together. If Feynman had the courage of his convictions, and ultimately the courage to go his own way in the world, both intellectually and otherwise, it was in no small part due to Arline and his memory of her.