I imagine experimental physicists must often look with envy at men like Kamerlingh Onnes, who discovered a field like low temperature, which seems to be bottomless and in which one can go down and down. Such a man is then a leader and has some temporary monopoly in a scientific adventure. Percy Bridgman, in designing a way to obtain higher pressures, opened up another new field and was able to move into it and to lead us all along. The development of ever higher vacuum was a continuing development of the same kind. Read more

You look in a mirror, and let's say you part your hair on the right side. You look in the mirror, and your image has its hair parted on the left side, so the image is left-to-right mixed up. But it's not top-to-bottom mixed up, because the top of the head of the image is there at the top, and the feet are down at the bottom. The question is: how does the mirror know to get the left and right mixed up, but not the up and down? See more

Feynman was known to be passionate about drumming, but he was irritated when people found this surprising in a famous scientist. In 1966 a Swedish encyclopedia publisher wrote asking for a photograph of Feynman "beating the drum" to give "a human approach to a presentation of the difficult matter that theoretical physics represents." This was his reply:

The fact that I beat a drum has nothing to do with the fact that I do theoretical physics. Theoretical physics is a human endeavor, one of the higher developments of human beings, and the perpetual desire to prove that people who do it are human by showing that they do other things that a few other humans do (like playing bongo drums) is insulting to me.

“If we interrupt the course of the event before its conclusion with an observation on the state of the particles involved in the event, we disturb the construction of the overall amplitude ... the amplitudes associated with the excluded states can no longer be added in as alternatives in computing the overall amplitude. ... Further, it does not matter if we actually observe and record the outcome of the measurement or not, so long as the measurement equipment is working. Obviously, we could observe the outcome anytime we wished. The operation of the measuring equipment is sufficient to disturb the system and its probability amplitude.” Read more

It this were the only law of this character it would be interesting and rather annoying. But what turns out to be true is that the more we investigate, the more laws we find, and the deeper we penetrate nature, the more this disease persists. Every one of our laws is a purely mathematical statement in rather complex and abstruse mathematics. Newton's statement of the law of gravitation is relatively simple mathematics. It gets more and more abstruse and more and more difficult as we go on. Why? I have not the slightest idea. It is only my purpose here to tell you about this fact. The burden of the lecture is just to emphasize the fact that it is impossible to explain honestly the beauties of the laws of nature in a way that people can feel, without their having some deep understanding of mathematics. I am sorry, but this seems to be the case. Read More

There's another thing that seems to happen a lot in modern physics: the discovery of applications for kinds of mathematics that were previously "pure," such as matrix algebra or group theory. Are physicists more receptive now than they used to be? Is the time lag less?

There never was any time lag. Take Hamilton's quaternions: The physicists threw away most of this very powerful mathematical system and kept only the part--the, mathematically, almost trivial part--that became vector analysis. But when the whole power of quaternions was needed, for quantum mechanics, Pauli reinvented the system on the spot in a new form. Now, you can look back and say that Pauli's spin matrices and operators were nothing but Hamilton's quaternions...but even if physicists had kept the system in mind for ninety years, it wouldn't have made more than a few weeks' difference.

Say you've got a disease, Werner's granular meclosis or whatever, and you look it up in a medical reference book. You may well find that you then know more about it than your doctor does, although he spent all that time in medical school, you see? It's much easier to learn about some special, restricted topic than a whole field. The mathematicians are exploring in all directions, and it's quicker for a physicist to catch up on what he needs than to try to keep up with everything that might conceivably be useful. The problem I was mentioning earlier, the difficulties with the equations in the quark theories, it's the physicists' problem, and we're going to solve it, and maybe when we solve it we'll be doing mathematics. It's a marvelous fact, and one I don't understand, that the mathematicians had investigated groups and so on before they turned up in physics--but in regard to the speed of progress in physics, I don't think it's all that significant. Read More