ConsciousnessI had a long talk with Feynmann once about "consciousness". I proposed that consciousness was extremely interesting because it is the only observed experience that seems to transcend physical laws. That is, our mental activity is a chemical and electrical process, awareness seems unnecessary and supernatural.
He was very cautious about the use of undefined but evocative words like "mind" and "consciousness". He said that people seem at first to have a common definition, but when you really try to talk with someone about consciousness, you discover that their personal definition is different from your own.
He had long arguments with his son about this. His son believed that the word "consciousness" was sort of trivial, just meaning "awake". He perversely refused to accept any deeper meaning of the word.
Feynmann thought that people just learned to manipulate this word, as they acquired language, and perhaps it is meaningless -- maybe. But he did think there was something paradoxical and very interesting about the word.
Red and Blue ElectronsI sat in on a second-term course on Field Theory. I would say that Feynmann was a bit moody and some days he seemed well prepared, and other days he would wonder out loud if he should just cancel the course. He seemed to feel frustrated, like he was trying to get something across that wasn't sinking in.
One day as usual, here was a huge expression on the board, and students were suggesting changes to try to fit it to some set of properties. Someone would say "what if we added an S squared term", and Feynmann would instantly say "Now that's interesting, if there were an S-squared term, then such-and-such would happen, and something-or-other wouldn't be conserved". One student insisted that a change he suggested was OK. Feynmann was annoyed because the student was being formal without making a connection to physics. The student was saying something about a property of some matrix, and Feynmann said loudly (switching characteristically to a New York accept with poor grammer) "I don't give a damn if the matrix is hermitian. That change would add another quantum number to the electron. Now you got red electrons and blue electrons, and with that extra degree of freedom, there would be an observable change in the thermodynamics of matter."
So, he was quick. Obviously, he had already gone over all these possibilities. He would pace up and down in front of the blackboard, flipping a piece of chalk nervously and hitching up his pants now and then.
How To Solve Unsolvable ProblemsThe best lecture I recall started out with Feynmann suggesting that he stop the course, because it wasn't really getting anyplace. Then he decided to talk about what he was doing right then, as an example of real research. He was interested in quantum chromodynamics, and the big frustration at the time was that people had a theory, but it was too difficult to evaluate it and predict numerical results of experiments.
He explained that in cases like this, it was hard to know where to start. He wanted to "understand" aspects of the theory, and develop intuition. For example, asymptotic confinement (quarks seem to bind together more tightly as you pull them apart).
He told us that he approaches these issues by rehearsal. 'Think of a simpler problem that seems similar. If you can't solve that, think of a simpler one. If you can solve it, then SOLVE IT. Don't just say you know how to solve it. After that, you might think of a way to attack the harder problem. You might realize something.' Basically, keep poking around and give your intuition a chance to develop and wait for ideas to pop into your head.
He suggested looking at an hydrogen atom in 2D. He noted that in that case, there was an infinite ionization energy, all the states were bound. He did some of the work on the board with class participation (and people occasionally yelling out minor corrections to his math). Everyone was very excited and eager. He computed the energy levels. Then he computed the width of the energy bands. They overlapped! What did that mean? Was the energy really quantized, or did it behave like a continuum then? It was amazing that such a trivial problem would quickly lead to a mystery.
He ended the lecture by charging everyone with the task of "learning something new about two dimensions" that they could report to the class. "Anything new. I don't care how trivial it is." And he meant "anything". He wasn't the least bit afraid to do something trivial, but maybe with a different viewpoint. Then show it to people with delight. He wasn't the least bit afraid to ask a dumb question at a talk--often a question that lots of other people wanted to ask.
The Use of NotebooksFeynman told us a few times to keep notebooks. When working on a hard problem, spend hours of concentrated time. People who don't think for hours without interruption cannot solve hard problems in his opinion. When you stop, try to save your mental state in the notebook. Learn to write notes that allow you to pick up your train of thought. In this way, days of sustained thought could be brought to bear on an extremely hard problem.
I've never met a "genius" of the style you sometimes see in movies, who had an effortless, super-human intelligence. There are glib people who seem to talk that talk, but they are fakes. The great scientists I've met worked hard, and Feynman stated explicitly that you had to work and be methodical to make substantial discoveries.
The World's Smartest ManAt one of the weekly Physics Colloquia, Feynman came in carrying an issue of OMNI magazine. They had just interviewed him, and he thought the magazine was kind of cool. Then the issue with him in it appeared on the news stands, a big picture of his face on the cover and the title, "World's Smartest Man". This bothered Feynman, who didn't really like that kind of talk. To add to the weirdness, there was a companion article about the world's smartest woman, someone from MENSA who had scored over 200 on an IQ test. Feynman enjoyed pointing out that his IQ was very modest, like 120-something. Of course, people into puzzles and IQ tests can practice their score up to very high levels, which then means absolutely nothing.