IRC-Galleria

The same thrill, the same awe and mystery, come again and again when we look at any problem deeply enough. With more knowledge comes deeper, more wonderful mystery, luring one on to penetrate deeper still. Never concerned that the answer may prove disappointing, but with pleasure and confidence we turn over each new stone to find unimagined strangeness leading on to more wonderful questions and mysteries -- certainly a grand adventure!


It is true that few unscientific people have this particular type of religious experience. Our poets do not write about it; our artists do not try to portray this remarkable thing. I don't know why. Is nobody inspired by our present picture of the universe? The value of science remains unsung by singers, so you are reduced to hearing -- not a song or a poem, but an evening lecture about it. This is not yet a scientific age.


Perhaps one of the reasons is that you have to know how to read the music. For instance, the scientific article says, perhaps, something like this: "The radioactive phosphorus content of the cerebrum of the rat decreases to one-half in a period of two weeks." Now, what does that means?


It means that phosphorus that is in the brain of a rat (and also in mine, and yours) is not the same phosphorus as it was two weeks ago, but that all of the atoms that are in the brain are being replaced, and the ones that were there before have gone away.




So what is this mind, what are these atoms with consciousness? Last week's potatoes! That is what now can remember what was going on in my mind a year ago -- a mind which has long ago been replaced.


That is what it means when one discovers how long it takes for the atoms of the brain to be replaced by other atoms, to note that the thing which I call my individuality is only a pattern or dance. The atoms come into my brain, dance a dance, then go out; always new atoms but always doing the same dance, remembering what the dance was yesterday.

Thirty-one years ago [1949], Richard Feynman told me about his "sum
over histories" version of quantum mechanics. "The electron does
anything it likes," he said. "It just goes in any direction at any
speed, forward or backward in time, however it likes, and then you add
up the amplitudes and it gives you the wave-function." I said to him,
"You're crazy." But he wasn't.

* Freeman J. Dyson, 1983

Feynman checkerboard with two paths contributing to the sum for the propagator
from (x / εc, t / ε) = (0, 0) to (3, 7).


The Feynman Checkerboard or Relativistic Chessboard model was Richard Feynman’s sum-over-paths formulation of the kernel for a free spin ½ particle moving in one spatial dimension. It provides a representation of solutions of the Dirac equation in (1+1)-dimensional spacetime as discrete sums.

It can be puzzling as to why a rotation of 720 degrees or two turns is necessary to return to the original state. This comes about because in quantum theory the state of a particle or system is represented by a complex probability amplitude and then when a measurement is made on the system the probability of it coming out some way is given by the square of absolute value of the appropriate amplitude.

Say you send a particle into a system with a detector that can be rotated where the probabilities of it detecting some state are affected by the rotation. When the system is rotated through 360 degrees the observed output and physics are the same as at the start but the amplitudes are changed for a spin ½ particle by a factor of -1 or a phase shift of half of 360 degrees. When the probabilities are calculated the -1 is squared and equals a factor of one so the predicted physics is same as in the starting position. Also in a spin 1/2 particle there are only two spin stated and the amplitudes for both change by the same -1 factor so the interference effects are identical unlike the case for higher spins. The complex probability amplitudes are something of a theoretical construct and cannot be directly observed.

If the probability amplitudes changed by the same amount as the rotation of the equipment then they would have changed by a factor of -1 when the equipment was rotated by 180 degrees which when squared would predict the same output as at the start but this is wrong experimentally. If you rotate the detector 180 degrees the output with spin ½ particles can be different to what it would be if you did not hence the factor of a half is necessary to make the predictions of the theory match reality.

The Checkerboard model is important because it connects aspects of spin and chirality with propagation in spacetime and is the only sum-over-path formulation in which quantum phase is discrete at the level of the paths, taking only values corresponding to the 4th roots of unity.

27/100
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play bongo -> win nobel prize -> chase some skirt

Statement stands for itself.

A few years after I gave some lectures for the freshmen at Caltech (which were published as the Feynman Lectures on Physics), I received a long letter from a feminist group. I was accused of being anti-woman because of two stories: the first was a discussion of the subtleties of velocity, and involved a woman driver being stopped by a cop. There's a discussion about how fast she was going, and I had her raise valid objections to the cop's definitions of velocity. The letter said I was making the woman look stupid.

The other story they objected to was told by the great astronomer Arthur Eddington, who had just figured out that the stars get their power from burning hydrogen in a nuclear reaction producing helium. He recounted how, on the night after his discovery, he was sitting on a beach with his girlfriend. She said, "Look how pretty the stars shine!" To which he replied, "Yes, and right now, I'm the only man in the world who knows how they shine." He was describing a kind of wonderful loneliness you have when you make a discovery.

The letter claimed that I was saying a woman is incapable of understanding nuclear reactions.

I figured there was no point in trying to answer their accusations in detail, so I wrote a short letter back to them: "Don't bug me, man!"

Needless to say, that didn't work too well. Another letter came: "Your response to our letter of September 29th is unsatisfactory . . ." -- blah, blah, blah. This letter warned that if I didn't get the publisher to revise the things they objected to, there would be trouble.

I ignored the letter and forgot about it.

A year or so later, the American Association of Physics Teachers awarded me a prize for writing those books, and asked me to speak at their meeting in San Fransisco. My sister, Joan, lived in Palo Alto -- an hour's drive away -- so I stayed with her the night before and we went to the meeting together.

As we approached the lecture hall, we found people standing there giving out handbills to everybody going in. We each took one, and glanced at it. At the top it said, "A PROTEST." Then it showed excerpts from the letters they sent me, and my response (in full). It concluded in large letters: "FEYNMAN SEXIST PIG!"

Joan stopped suddenly and rushed back: "These are interesting," she said to the protester. "I'd like some more of them!"

When she caught up with me, she said, "Gee whiz, Richard; what did you do?"

I told her what had happened as we walked into the hall.

At the front of the hall, near the stage, were two prominent woman in the American Association of Physics Teachers. One was in charge of women's affairs for the organization, and the other was Fay Ajzenberg, a professor of physics I knew, from Pennsylvania. They saw me coming down towards the stage accompanied by this woman with a fistful of handbills, talking to me. Fay walked up to her and said, "Do you realize that Professor Feynman has a sister that he encouraged to go into physics, and that she has a Ph.D in physics?"

"Of course I do," said Joan. "I am that sister!"

Fay and her associate explained to me that the protesters were a group -- led by a man, ironically -- who were always disrupting meetings in Berkeley. "We'll sit on either side of you to show our solidarity, and just before you speak, I'll get up and say something to quiet the protesters," Fay said.

Because there was another talk before mine, I had time to think of something to say. I thanked Fay, but declined her offer.

As soon as I got up to speak, half a dozen protesters marched down to the front of the lecture hall and paraded right below the stage, holding their picket signs high, chanting, "Feynman sexist pig! Feynman sexist pig!"

I began my talk by telling the protesters, "I'm sorry that my short answer to your letter brought you here unnecessarily. There are more serious places to direct one's attention towards improving the status of women in physics than these relatively trivial mistakes -- if that's what you want to call them -- in a textbook. But perhaps, after all, it's good that you came. For women do indeed suffer from prejudice and discrimination in physics, and your presence here today serves to remind us of these difficulties and the need to remedy them."

The protesters looked at one another. Their picket signs began to come slowly down, like sails in a dying wind.

I continued: "Even though the American Association of Physics Teachers has given me an award for teaching, I must confess I don't know how to teach. Therefore, I have nothing to say about teaching. Instead, I would like to talk about something that will be especially interesting to the women in the audience: I would like to talk about the structure of the proton."

The protesters put their picket signs down and walked off. My hosts told me later that the man and his group of protesters had never been defeated so easily.

(Recently I discovered a transcript of my speech, and what I said at the beginning doesn't seem anywhere near as dramatic as the way I remember it. What I remember saying is much more wonderful than what I actually said!)

After my talk, some of the protesters came up to press me about the woman-driver story. "Why did it have to be a woman driver?" they said. "You are implying that all women are bad drivers."

"But the woman makes the cop look bad," I said. "Why aren't you concerned about the cop?"

"That's what you expect from cops! one of the protesters said. "They're all pigs!"

"But you should be concerned," I said. "I forgot to say in the story that the cop was a woman!"

--
Richard P. Feynman - What Do You Care What Other People Think?

Just at this moment, my sister sends me a postcard from Oberlin, where she's going to college. It's written in pencil, with small symbols - it's in Chinese.

Joan is nine years younger than I am, and studied physics, too. having me as her older brother was tough on her. She was always looking for something I couldn't do, and was secretly taking Chinese.

Well, I didn't know any Chinese, but one thing I'm good at is spending an infinite amount of time solving a puzzle. The next weekend I took the card with me to Albuquerque. Arlene showed me how to look up the symbols. You have to start in the back of the dictionary with the right category and count the number of strokes. Then you go into the main part of the dictionary. It turns out each symbol has several possible meanings, and you have to put several symbols together before you can understand it.

With great patience I worked everything out. Joan was saying things like, "I had a good time today." There was only one sentence I couldn't figure out. It said, "Yesterday we celebrated mountain-forming day" - obviously an error. (It turned out they did have some crazy thing called "Mountain-forming Day" at Oberlin, and I had translated it right!)

So it was trivial things like you'd expect to have on a postcard, but I knew from the situation that Joan was trying to floor me by sending Chinese.

I looked back and forth through the art book and picked out four symbols which would go well together. Then I practiced each one, over and over. I had a big pad of paper, and I would make fifty of each one, until I got it just right.

When I had accidentally made one good example of each symbol, I saved them. Arlene approved, and we glued the four of them end to end, one on top of the other. Then we put a little piece of wood on each end, so you could hang it up on the wall. I took a picture of my masterpiece with Nick Metropolis's camera, rolled up the scroll, put it in a tube, and sent it to Joan.

So she gets it. She unrolls it, and she can't read it. It looks to her as if I simply made four characters, one right after the other, on the scroll. She takes it to her teacher.

The first thing he says is, "This is written rather well! Did you do this?"

"Uh, no. What does it say?"

"Elder brother also speaks."

I'm a real bastard - I would never let my little sister score one on me.

--
Richard P. Feynman - What Do You Care What Other People Think?

"Arlene and I began to mold each other's personality. She lived in a family that was very polite, and was very sensitive to other people's feelings. She taught me to be more sensitive to those kinds of things, too. On the other hand, her family felt that "white lies" were okay.

I thought one should have the attitude of "What do you care what other people think" I said, "We should listen to other people's opinions and take them into account. Then, if they don't make sense and we think they're wrong, then that's that!"

Arlene caught on to the idea right away. It was easy to talk her into thinking that in our relationship, we must be very honest with each other and say everything straight with absolute frankness. It worked very well, and we became very much in love - a love like no other love that I know of.


--

It's hard to explain. If a Martian (who, we'll imagine, never dies except by accident) came to Earth and saw this peculiar race of creatures - these humans who live about seventy or eighty years, knowing that death is going to come - it would look to him like a terrible problem of psychology to live under those circumstances, knowing that life is only temporary. Well, we humans somehow figure out how to live despite this problem: we laugh, we joke, we live.

The only difference for me and Arlene was, instead of fifty years, it was five years. It was only a quantitative difference - the psychological problem was just the same. The only way it would have become any different is if we had said to ourselves, "But those other people have it better, because they might live fifty years." But that's crazy. Why make yourself miserable saying things like, "Why do we have such bad luck? What has God done to us? What have we done to deserve this?" - all of which, if you understand reality and take it completely into your heart, are irrelevant and unsolvable. They are just things that nobody can know. Your situation is just an accident of life.

We had a hell of a good time together.

I came back into her room. I kept imaginig all the things that were going on physiologically: the lungs aren't getting enough air into the blood, which makes the brain fogged out and the heart weaker, which makes the breating even more difficult. I kept expecting some sort of avalanching effect, but everyhing caving in together in a dramatic collapse. But it didn't appear that way at all: she just slowly got more foggy, and her breathing gradually became less and less, until there was no more breath - but just before that, there was a very small one.

The nurse on her round came in and confirmed that Arlene was dead, and went out - I wanted to be alone for a moment. I sat there for a while, and then went over to kiss her one last time.

I was very surprised to discover that her hair smelled exactly the same. Of course, after I stopped and thought about it, there was no reason why hair should smell different in such a short time. But to me it was a kind of a shock, because in my mind, something enormous had just happened - and yet nothing had happened.

--

One night I had a dream, and Arlene came into it. Right away, I said to her, "No, no, you can't be in this dream. You're not alive!"

Then later, I had another dream with Arlene in it. I started in again, saying, "You can't be in this dream!"
"No, no," she says. "I fooled you. I was tired of you, so I cooked up this ruse so I could go my own way. But now I like you again, so I've come back." My mind was really working against itself. It had to be explained, even in a goddamn dream, why it was possible that she was still there!

I must have done something to myself, psychologically. I didn't cry until about a month later, when I was walking past a department store in Oak Ridge and noticed a pretty dress in the window. I thought, "Arlene would like that," and then it hit me.

--
Richard P. Feynman - What Do You Care What Other People Think?