Chapter 12 The second part accidentally broke into Princeton-4

When I was in graduate school at Princeton, I worked as a research assistant for Professor Wheeler.He gave me a topic, but I didn't expect it to be too difficult to do.So I went back and studied an idea I had back in my MIT days, which is that electrons don't act on themselves, they only interact with other electrons. Here's the problem: when an electron wobbles, it radiates electromagnetic waves, which equals a radiance of energy, and the loss of energy means that there is some force acting on the electron. Considering it further, the force used to shake a charged electron must be different from the force used to shake an uncharged electron.For assuming that the force is exactly the same in both cases, but the particle is known to lose energy in one case and not in the other - it would appear to be two different versions of the same problem. The answer is simply impossible.

The standard theory at the time was that the electrons act on themselves to produce a force called the "radiation reaction".I didn't pay attention to this problem when I started to hone the idea at MIT; I always thought that electrons only act on other electrons.It wasn't until I got to Princeton that I heard about these standard theories and realized that the original concept was in serious trouble. At this time, my idea is: first let this electron vibrate, and then according to my idea, it will act on nearby electrons to make them (they) vibrate.The effect produced by these disturbed electrons is the source of the radiation reaction force.So I did some calculations and went to Professor Wheeler with the results.

Professor Wheeler didn't think about it, and immediately said: "Oh, this is wrong, because you are saying that it is inversely proportional to the square of the distance between it and other electrons, but it should not be related to these variables. Moreover, it should be proportional to the mass of other electrons." Inversely proportional to the charge of the other electrons." What makes me sad is how he has done these calculations.Then I realized that with a master like Wheeler, you give him a question and he can "look" immediately Get the point out of it. He continued: "And this is subject to delays because the radiation waves return later.

So what you describe is nothing more than reflected light. " "Oh! Of course." I said dejectedly. "Wait a minute," he said, "let's assume that the reflected light is a forward wave, in other words, a reaction against time; then it returns in normal time. We already know that this effect scales with the square of the distance." Inversely proportional, if there are many electrons filling the whole space, and the number of electrons is inversely proportional to the square of the distance, maybe all the effects can just cancel each other out." We found that this idea actually works.The result of the recalculation was perfect, and all aspects corresponded correctly.Within the realm of classical physics, this theory is likely to be true, although it is very different from the standard theories proposed by James Clerk Maxwell or Hendrik Antoon Lorentz.But it doesn't have the troubles of some infinite quantities that appear in the electron self-action theory; it's very clever and includes the physics of actions, delay effects, forwards and backwards in time, and so on.We call this set of theories "half-lead-half-delay potential".

Wheeler and I felt that the next step would be to turn to quantum electrokinetic theory, because I think the difficulty of electron self-action arises there as well.We imagine that if we can overcome this difficulty in classical physics, and then develop a set of quantum theory from it, it is equivalent to correcting the lack of quantum theory at the same time. We may say that we have got the classical theoretical part figured out.Then Wheeler said to me: "Feynman, you're young, you should give a seminar presentation on this topic, you need to practice speaking more. In the meantime I'll get the quantum theory part out and give a presentation later." That will be my During the first academic report, Wheeler went to talk to Professor Eugene Wigner and put me in the seminar schedule.

A day or two before my turn to give the presentation, I bumped into Wigner in the hallway. "Feynman," he said, "I think your research with Wheeler is very interesting, so I have invited Russell to attend your seminar." Russell (Henry NorrisRussell), a famous contemporary astronomer, wants to listen my report! Wigner continued: "I think Professor von Neumann would also be interested." John von Neumann was the greatest mathematician of his time. "And it happened that Professor Bao Li came to visit from Switzerland, so I also invited Bao Li to come." Oh my god!Wolfgang Pauli, winner of the Nobel Prize in Physics in 1945, is also a famous physicist!At this time, I was so scared that my face turned yellow.Finally Wigner said:

"Professor Einstein rarely participates in our weekly seminars, but your topic is so interesting, so I specially invite him, and he will come too." My face must have turned green by then, because Wigner also said, "No! No!Don't worry!But I have to warn you first: if Professor Russell dozed off while listening - and he will fall asleep - it does not mean that your presentation is bad, he dozed off in every seminar.On the other hand, don't be complacent if Professor Bowley keeps nodding his head as if he agrees with everything you say, Professor Bowley suffers from Parkinsonism. "

I went back and told Wheeler.He asked me to do lecture practice, and now I have these masters of science coming to listen to my lectures, which makes me very uncomfortable. "It's okay," he said, "don't worry, I'll answer all your questions for you." I worked hard to prepare the report, and when the day came, I ran into the venue and made the same mistake as many young people who have never given an academic report—writing too many equations on the blackboard.You know, young lads don't know when to say, "Of course, this is inversely proportional to that, and it's going to go like this..."

Because in fact, the audience here already knew this, and they all "seeed" it; but only he himself didn't know it.He had to rely on actual calculations to reach conclusions - so he wrote a lot of equations. Before the meeting, I had written a lot up and down on the blackboard, and I was still writing. Einstein ran in and said with a pleasant face, "Hello, I'm here to attend your seminar. Excuse me, where is the tea placed?" where?" I told him and went on to write my equations. Report time has finally arrived.I have these science gurus sitting in front of me, all waiting for me to speak!It was the first academic report in my life, but I met such an audience!

I mean, they're going to ask a lot of hard questions, and I'm going to make a big fool of myself! I still clearly remember that when I took out the speech from the brown paper bag, my hands couldn't stop shaking. But a miracle happened—in fact, I was lucky, similar miracles happened again and again in my life—as soon as I started to think about physics, I had to concentrate on the problem to be explained, and there was no other distracting thoughts in my head, not at all. will be nervous.So when I started my presentation, I had no idea who the audience was; I was just explaining these physics concepts.It's that simple!

The report ends and the question section begins.Pauli, who was sitting next to Einstein, stood up first and said: "I don't think this theory is correct, because of this, this and this..." He turned to Einstein and asked: "Do you agree, Professor Einstein?" ?” Einstein said: "No—," the voice was drawn out, with a thick German accent, and it was a very pleasant "no", which was very polite. "I just think it must be very difficult to come up with the same theory for gravitational interactions," he said, referring to general relativity, his beloved "baby."He continued: "Because we don't have enough experimental evidence so far, I'm not sure which is the correct theory of gravity." Einstein understood that many ideas may be different from his theory, and he was very tolerant of others. idea. I really wish I had written down what Pauli said at the time, because a few years later, I found that that set of theories was not enough to construct quantum theory.It is probable that the great Pauli had noticed the problem, and had explained it to me at the time; but since I was too relaxed to answer the question, I did not listen carefully. I do remember walking up the steps of the library in Palma with Pauli, and he asked me, "When Wheeler gives a talk on quantum theory, what's he going to say?" I said, "I don't know, he didn't tell me. That's part of what he does." "Oh?" he said, "this guy is doing it all by himself and not telling the assistant exactly what he's doing?" He leaned over and said in a low, mysterious tone: "Wheeler won't be giving that speech." Sure enough, Wheeler never filed a report.At first he thought that the parts related to quantum theory could be easily solved; he thought he had almost done it, but in fact he didn't.When it came time for his report, he realized that he had no idea what to do, so he had nothing to report.I have never solved the quantum theory of "half-advance-half-delay potential".And to be honest, I have spent many years working on it!