Index
"Surely You're Joking, Mr. Feynman!" by Richard P. Feynman -------- Part 2 The Princeton Years -------- "Surely You're Joking, Mr. Feynman!" When I was an undergraduate at MIT I loved it. I thought it was a great place, and I wanted to go to graduate school there too, of course. But when I went to Professor Slater and told him of my intentions, he said, "We won't let you in here." I said, "What?" Slater said, "Why do you think you should go to graduate school at MIT?" "Because MIT is the best school for science in the country." "You think that?" "Yeah." "That's why you should go to some other school. You should find out how the rest of the world is." So I decided to go to Princeton. Now Princeton had a certain aspect of elegance. It was an imitation of an English school, partly. So the guys in the fraternity, who knew my rather rough, informal manners, started making remarks like "Wait till they find out who they've got coming to Princeton! Wait till they see the mistake they made!" So I decided to try to be nice when I got to Princeton. My father took me to Princeton in his car, and I got my room, and he left. I hadn't been there an hour when I was met by a man: "I'm the Mahstah of Residences heah, and I should like to tell you that the Dean is having a Tea this aftanoon, and he should like to have all of you come. Perhaps you would be so kind as to inform your roommate, Mr. Serette." That was my introduction to the graduate "College" at Princeton, where all the students lived. It was like an imitation Oxford or Cambridge -- complete with accents (the master of residences was a professor of "French littrachaw"). There was a porter downstairs, everybody had nice rooms, and we ate all our meals together, wearing academic gowns, in a great hall which had stained-glass windows. So the very afternoon I arrived in Princeton I'm going to the dean's tea, and I didn't even know what a "tea" was, or why! I had no social abilities whatsoever; I had no experience with this sort of thing. So I come up to the door, and there's Dean Eisenhart, greeting the new students: "Oh, you're Mr. Feynman," he says. "We're glad to have you." So that helped a little, because he recognized me, somehow. I go through the door, and there are some ladies, and some girls, too. It's all very formal and I'm thinking about where to sit down and should I sit next to this girl, or not, and how should I behave, when I hear a voice behind me. "Would you like cream or lemon in your tea, Mr. Feynman?" It's Mrs. Eisenhart, pouring tea. "I'll have both, thank you," I say, still looking for where I'm going to sit, when suddenly I hear "Heh-heh-heh-heh-heh. Surely you're joking, Mr. Feynman." Joking? Joking? What the hell did I just say? Then I realized what I had done. So that was my first experience with this tea business. Later on, after I had been at Princeton longer, I got to understand this "Heh-heh-heh-heh-heh." In fact it was at that first tea, as I was leaving, that I realized it meant "You're making a social error." Because the next time I heard this same cackle, "Heh-heh-heh-heh-heh," from Mrs. Eisenhart, somebody was kissing her hand as he left. Another time, perhaps a year later, at another tea, I was talking to Professor Wildt, an astronomer who had worked out some theory about the clouds on Venus. They were supposed to be formaldehyde (it's wonderful to know what we once worried about) and he had it all figured out, how the formaldehyde was precipitating, and so on. It was extremely interesting. We were talking about all this stuff, when a little lady came up and said, "Mr. Feynman, Mrs. Eisenhart would like to see you." "OK, just a minute..." and I kept talking to Wildt. The little lady came back again and said, "Mr. Feynman, Mrs. Eisenhart would like to see you." "OK, OK!" and I go over to Mrs. Eisenhart, who's pouring tea. "Would you like to have some coffee or tea, Mr. Feynman?" "Mrs. So-and-so says you wanted to talk to me." "Heh-heh-heh-heh-heh. Would you like to have coffee, or tea, Mr. Feynman?" "Tea," I said, "thank you." A few moments later Mrs. Eisenhart's daughter and a schoolmate came over, and we were introduced to each other. The whole idea of this "heh-heh-heh" was: Mrs. Eisenhart didn't want to talk to me, she wanted me over there getting tea when her daughter and friend came over, so they would have someone to talk to. That's the way it worked. By that time I knew what to do when I heard "Heh-heh-heh-heh-heh." I didn't say, "What do you mean, 'Heh-heh-heh-heh-heh'?"; I knew the "heh-heh-heh" meant "error," and I'd better get it straightened out. Every night we wore academic gowns to dinner. The first night it scared the life out of me, because I didn't like formality. But I soon realized that the gowns were a great advantage. Guys who were out playing tennis could rush into their room, grab their academic gown, and put it on. They didn't have to take time off to change their clothes or take a shower. So underneath the gowns there were bare arms, T-shirts, everything. Furthermore, there was a rule that you never cleaned the gown, so you could tell a first-year man from a second-year man, from a third-year man, from a pig! You never cleaned the gown and you never repaired it, so the first-year men had very nice, relatively clean gowns, but by the time you got to the third year or so, it was nothing but some kind of cardboard thing on your shoulders with tatters hanging down from it. So when I got to Princeton, I went to that tea on Sunday afternoon and had dinner that evening in an academic gown at the "College." But on Monday, the first thing I wanted to do was to see the cyclotron. MIT had built a new cyclotron while I was a student there, and it was just beautiful! The cyclotron itself was in one room, with the controls in another room. It was beautifully engineered. The wires ran from the control room to the cyclotron underneath in conduits, and there was a whole console of buttons and meters. It was what I would call a gold-plated cyclotron. Now I had read a lot of papers on cyclotron experiments, and there weren't many from MIT. Maybe they were just starting. But there were lots of results from places like Cornell, and Berkeley, and above all, Princeton. Therefore what I really wanted to see, what I was looking forward to, was the PRINCETON CYCLOTRON. That must be something. So first thing on Monday, I go into the physics building and ask, "Where is the cyclotron -- which building?" "It's downstairs, in the basement -- at the end of the hall." In the basement? It was an old building. There was no room in the basement for a cyclotron. I walked down to the end of the hall, went through the door, and in ten seconds I learned why Princeton was right for me -- the best place for me to go to school. In this room there were wires strung all over the place! Switches were hanging from the wires, cooling water was dripping from the valves, the room was full of stuff, all out in the open. Tables piled with tools were everywhere; it was the most godawful mess you ever saw. The whole cyclotron was there in one room, and it was complete, absolute chaos! It reminded me of my lab at home. Nothing at MIT had ever reminded me of my lab at home. I suddenly realized why Princeton was getting results. They were working with the instrument. They built the instrument; they knew where everything was, they knew how everything worked, there was no engineer involved, except maybe he was working there too. It was much smaller than the cyclotron at MIT, and "gold-plated"? -- it was the exact opposite. When they wanted to fix a vacuum, they'd drip glyptal on it, so there were drops of glyptal on the floor. It was wonderful! Because they worked with it. They didn't have to sit in another room and push buttons! (Incidentally, they had a fire in that room, because of all the chaotic mess that they had -- too many wires -- and it destroyed the cyclotron. But I'd better not tell about that!) (When I got to Cornell I went to look at the cyclotron there. This cyclotron hardly required a room: It was about a yard across -- the diameter of the whole thing. It was the world's smallest cyclotron, but they had got fantastic results. They had all kinds of special techniques and tricks. If they wanted to change something in the "D's" -- the D-shaped half circles that the particles go around -- they'd take a screwdriver, and remove the D's by hand, fix them, and put them back. At Princeton it was a lot harder, and at MIT you had to take a crane that came rolling across the ceiling, lower the hooks, and it was a hellllll of a job.) I learned a lot of different things from different schools. MIT is a very good place; I'm not trying to put it down. I was just in love with it. It has developed for itself a spirit, so that every member of the whole place thinks that it's the most wonderful place in the world -- it's the center, somehow, of scientific and technological development in the United States, if not the world. It's like a New Yorker's view of New York: they forget the rest of the country. And while you don't get a good sense of proportion there, you do get an excellent sense of being with it and in it, and having motivation and desire to keep on -- that you're specially chosen, and lucky to be there. So MIT was good, but Slater was right to warn me to go to another school for my graduate work. And I often advise my students the same way. Learn what the rest of the world is like. The variety is worthwhile. I once did an experiment in the cyclotron laboratory at Princeton that had some startling results. There was a problem in a hydrodynamics book that was being discussed by all the physics students. The problem is this: You have an S-shaped lawn sprinkler -- an S-shaped pipe on a pivot -- and the water squirts out at right angles to the axis and makes it spin in a certain direction. Everybody knows which way it goes around; it backs away from the outgoing water. Now the question is this: If you had a lake, or swimming pool -- a big supply of water -- and you put the sprinkler completely under water, and sucked the water in, instead of squirting it out, which way would it turn? Would it turn the same way as it does when you squirt water out into the air, or would it turn the other way? The answer is perfectly clear at first sight. The trouble was, some guy would think it was perfectly clear one way, and another guy would think it was perfectly clear the other way. So everybody was discussing it. I remember at one particular seminar, or tea, somebody went up to Prof. John Wheeler and said, "Which way do you think it goes around?" Wheeler said, "Yesterday, Feynman convinced me that it went backwards. Today, he's convinced me equally well that it goes around the other way. I don't know what he'll convince me of tomorrow!" I'll tell you an argument that will make you think it's one way, and another argument that will make you think it's the other way, OK? One argument is that when you're sucking water in, you're sort of pulling the water with the nozzle, so it will go forward, towards the incoming water. But then another guy comes along and says, "Suppose we hold it still and ask what kind of a torque we need to hold it still. In the case of the water going out, we all know you have to hold it on the outside of the curve, because of the centrifugal force of the water going around the curve. Now, when the water goes around the same curve the other way, it still makes the same centrifugal force toward the outside of the curve. Therefore the two cases are the same, and the sprinkler will go around the same way, whether you're squirting water out or sucking it in." After some thought, I finally made up my mind what the answer was, and in order to demonstrate it, I wanted to do an experiment. In the Princeton cyclotron lab they had a big carboy -- a monster bottle of water. I thought this was just great for the experiment. I got a piece of copper tubing and bent it into an S-shape. Then in the middle I drilled a hole, stuck in a piece of rubber hose, and led it up through a hole in a cork I had put in the top of the bottle. The cork had another hole, into which I put another piece of rubber hose, and connected it to the air pressure supply of the lab. By blowing air into the bottle, I could force water into the copper tubing exactly as if I were sucking it in. Now, the S-shaped tubing wouldn't turn around, but it would twist (because of the flexible rubber hose), and I was going to measure the speed of the water flow by measuring how far it squirted out of the top of the bottle. I got it all set up, turned on the air supply, and it went "Puup!" The air pressure blew the cork out of the bottle. I wired it in very well, so it wouldn't jump out. Now the experiment was going pretty good. The water was coming out, and the hose was twisting, so I put a little more pressure on it, because with a higher speed, the measurements would be more accurate. I measured the angle very carefully, and measured the distance, and increased the pressure again, and suddenly the whole thing just blew glass and water in all directions throughout the laboratory. A guy who had come to watch got all wet and had to go home and change his clothes (it's a miracle he didn't get cut by the glass), and lots of cloud chamber pictures that had been taken patiently using the cyclotron were all wet, but for some reason I was far enough away, or in some such position that I didn't get very wet. But I'll always remember how the great Professor Del Sasso, who was in charge of the cyclotron, came over to me and said sternly, "The freshman experiments should be done in the freshman laboratory!" -------- Meeeeeeeeeee! On Wednesdays at the Princeton Graduate College, various people would come in to give talks. The speakers were often interesting, and in the discussions after the talks we used to have a lot of fun. For instance, one guy in our school was very strongly anti-Catholic, so he passed out questions in advance for people to ask a religious speaker, and we gave the speaker a hard time. Another time somebody gave a talk about poetry. He talked about the structure of the poem and the emotions that come with it; he divided everything up into certain kinds of classes. In the discussion that came afterwards, he said, "Isn't that the same as in mathematics, Dr. Eisenhart?" Dr. Eisenhart was the dean of the graduate school and a great professor of mathematics. He was also very clever. He said, "I'd like to know what Dick Feynman thinks about it in reference to theoretical physics." He was always putting me on in this kind of situation. I got up and said, "Yes, it's very closely related. In theoretical physics, the analog of the word is the mathematical formula, the analog of the structure of the poem is the interrelationship of the theoretical bling-bling with the so-and-so" -- and I went through the whole thing, making a perfect analogy. The speaker's eyes were beaming with happiness. Then I said, "It seems to me that no matter what you say about poetry, I could find a way of making up an analog with any subject, just as I did for theoretical physics. I don't consider such analogs meaningful." In the great big dining hall with stained-glass windows, where we always ate, in our steadily deteriorating academic gowns, Dean Eisenhart would begin each dinner by saying grace in Latin. After dinner he would often get up and make some announcements. One night Dr. Eisenhart got up and said, "Two weeks from now, a professor of psychology is coming to give a talk about hypnosis. Now, this professor thought it would be much better if we had a real demonstration of hypnosis instead of just talking about it. Therefore he would like some people to volunteer to be hypnotized..." I get all excited: There's no question but that I've got to find out about hypnosis. This is going to be terrific! Dean Eisenhart went on to say that it would be good if three or four people would volunteer so that the hypnotist could try them out first to see which ones would be able to be hypnotized, so he'd like to urge very much that we apply for this. (He's wasting all this time, for God's sake!) Eisenhart was down at one end of the hall, and I was way down at the other end, in the back. There were hundreds of guys there. I knew that everybody was going to want to do this, and I was terrified that he wouldn't see me because I was so far back. I just had to get in on this demonstration! Finally Eisenhart said, "And so I would like to ask if there are going to be any volunteers..." I raised my hand and shot out of my seat, screaming as loud as I could, to make sure that he would hear me: "MEEEEEEEEEEE!" He heard me all right, because there wasn't another soul. My voice reverberated throughout the hall -- it was very embarrassing. Eisenhart's immediate reaction was, "Yes, of course, I knew you would volunteer, Mr. Feynman, but I was wondering if there would be anybody else." Finally a few other guys volunteered, and a week before the demonstration the man came to practice on us, to see if any of us would be good for hypnosis. I knew about the phenomenon, but I didn't know what it was like to be hypnotized. He started to work on me and soon I got into a position where he said, "You can't open your eyes." I said to myself, "I bet I could open my eyes, but I don't want to disturb the situation: Let's see how much further it goes." It was an interesting situation: You're only slightly fogged out, and although you've lost a little bit, you're pretty sure you could open your eyes. But of course, you're not opening your eyes, so in a sense you can't do it. He went through a lot of stuff and decided that I was pretty good. When the real demonstration came he had us walk on stage, and he hypnotized us in front of the whole Princeton Graduate College. This time the effect was stronger; I guess I had learned how to become hypnotized. The hypnotist made various demonstrations, having me do things that I couldn't normally do, and at the end he said that after I came out of hypnosis, instead of returning to my seat directly, which was the natural way to go, I would walk all the way around the room and go to my seat from the back. All through the demonstration I was vaguely aware of what was going on, and cooperating with the things the hypnotist said, but this time I decided, "Damn it, enough is enough! I'm gonna go straight to my seat." When it was time to get up and go off the stage, I started to walk straight to my seat. But then an annoying feeling came over me: I felt so uncomfortable that I couldn't continue. I walked all the way around the hall. I was hypnotized in another situation some time later by a woman. While I was hypnotized she said, "I'm going to light a match, blow it out, and immediately touch the back of your hand with it. You will feel no pain." I thought, "Baloney!" She took a match, lit it, blew it out, and touched it to the back of my hand. It felt slightly warm. My eyes were closed throughout all of this, but I was thinking, "That's easy. She lit one match, but touched a different match to my hand. There's nothin' to that; it's a fake!" When I came out of the hypnosis and looked at the back of my hand, I got the biggest surprise: There was a burn on the back of my hand. Soon a blister grew, and it never hurt at all, even when it broke. So I found hypnosis to be a very interesting experience. All the time you're saying to yourself, "I could do that, but I won't" -- which is just another way of saying that you can't. -------- A Map of the Cat? In the Graduate College dining room at Princeton everybody used to sit with his own group. I sat with the physicists, but after a bit I thought: It would be nice to see what the rest of the world is doing, so I'll sit for a week or two in each of the other groups. When I sat with the philosophers I listened to them discuss very seriously a book called Process and Reality by Whitehead. They were using words in a funny way, and I couldn't quite understand what they were saying. Now I didn't want to interrupt them in their own conversation and keep asking them to explain something, and on the few occasions that I did, they'd try to explain it to me, but I still didn't get it. Finally they invited me to come to their seminar. They had a seminar that was like a class. It had been meeting once a week to discuss a new chapter out of Process and Reality -- some guy would give a report on it and then there would be a discussion. I went to this seminar promising myself to keep my mouth shut, reminding myself that I didn't know anything about the subject, and I was going there just to watch. What happened there was typical -- so typical that it was unbelievable, but true. First of all, I sat there without saying anything, which is almost unbelievable, but also true. A student gave a report on the chapter to be studied that week. In it Whitehead kept using the words "essential object" in a particular technical way that presumably he had defined, but that I didn't understand. After some discussion as to what "essential object" meant, the professor leading the seminar said something meant to clarify things and drew something that looked like lightning bolts on the blackboard. "Mr. Feynman," he said, "would you say an electron is an 'essential object'?" Well, now I was in trouble. I admitted that I hadn't read the book, so I had no idea of what Whitehead meant by the phrase; I had only come to watch. "But," I said, "I'll try to answer the professor's question if you will first answer a question from me, so I can have a better idea of what 'essential object' means. Is a brick an essential object?" What I had intended to do was to find out whether they thought theoretical constructs were essential objects. The electron is a theory that we use; it is so useful in understanding the way nature works that we can almost call it real. I wanted to make the idea of a theory clear by analogy. In the case of the brick, my next question was going to be, "What about the inside of the brick?" -- and I would then point out that no one has ever seen the inside of a brick. Every time you break the brick, you only see the surface. That the brick has an inside is a simple theory which helps us understand things better. The theory of electrons is analogous. So I began by asking, "Is a brick an essential object?" Then the answers came out. One man stood up and said, "A brick as an individual, specific brick. That is what Whitehead means by an essential object." Another man said, "No, it isn't the individual brick that is an essential object; it's the general character that all bricks have in common -- their 'brickness' -- that is the essential object." Another guy got up and said, "No, it's not in the bricks themselves. 'Essential object' means the idea in the mind that you get when you think of bricks." Another guy got up, and another, and I tell you I have never heard such ingenious different ways of looking at a brick before. And, just like it should in all stories about philosophers, it ended up in complete chaos. In all their previous discussions they hadn't even asked themselves whether such a simple object as a brick, much less an electron, is an "essential object." After that I went around to the biology table at dinner time. I had always had some interest in biology, and the guys talked about very interesting things. Some of them invited me to come to a course they were going to have in cell physiology. I knew something about biology, but this was a graduate course. "Do you think I can handle it? Will the professor let me in?" I asked. They asked the instructor, E. Newton Harvey, who had done a lot of research on light-producing bacteria. Harvey said I could join this special, advanced course provided one thing -- that I would do all the work, and report on papers just like everybody else. Before the first class meeting, the guys who had invited me to take the course wanted to show me some things under the microscope. They had some plant cells in there, and you could see some little green spots called chloroplasts (they make sugar when light shines on them) circulating around. I looked at them and then looked up: "How do they circulate? What pushes them around?" I asked. Nobody knew. It turned out that it was not understood at that time. So right away I found out something about biology: it was very easy to find a question that was very interesting, and that nobody knew the answer to. In physics you had to go a little deeper before you could find an interesting question that people didn't know. When the course began, Harvey started out by drawing a great, big picture of a cell on the blackboard and labeling all the things that are in a cell. He then talked about them, and I understood most of what he said. After the lecture, the guy who had invited me said, "Well, how did you like it?" "Just fine," I said. "The only part I didn't understand was the part about lecithin. What is lecithin?" The guy begins to explain in a monotonous voice: "All living creatures, both plant and animal, are made of little bricklike objects called 'cells'..." "Listen," I said, impatiently, "I know all that; otherwise I wouldn't be in the course. What is lecithin?" "I don't know." I had to report on papers along with everyone else, and the first one I was assigned was on the effect of pressure on cells -- Harvey chose that topic for me because it had something that had to do with physics. Although I understood what I was doing, I mispronounced everything when I read my paper, and the class was always laughing hysterically when I'd talk about "blastospheres" instead of "blastomeres," or some other such thing. The next paper selected for me was by Adrian and Bronk. They demonstrated that nerve impulses were sharp, single-pulse phenomena. They had done experiments with cats in which they had measured voltages on nerves. I began to read the paper. It kept talking about extensors and flexors, the gastrocnemius muscle, and so on. This and that muscle were named, but I hadn't the foggiest idea of where they were located in relation to the nerves or to the cat. So I went to the librarian in the biology section and asked her if she could find me a map of the cat. "A map of the cat, sir?" she asked, horrified. "You mean a zoological chart!" From then on there were rumors about some dumb biology graduate student who was looking for a "map of the cat." When it came time for me to give my talk on the subject, I started off by drawing an outline of the cat and began to name the various muscles. The other students in the class interrupt me: "We know all that!" "Oh," I say, "you do? Then no wonder I can catch up with you so fast after you've had four years of biology." They had wasted all their time memorizing stuff like that, when it could be looked up in fifteen minutes. After the war, every summer I would go traveling by car somewhere in the United States. One year, after I was at Caltech, I thought, "This summer, instead of going to a different place, I'll go to a different field." It was right after Watson and Crick's discovery of the DNA spiral. There were some very good biologists at Caltech because Delbrück had his lab there, and Watson came to Caltech to give some lectures on the coding systems of DNA. I went to his lectures and to seminars in the biology department and got full of enthusiasm. It was a very exciting time in biology, and Caltech was a wonderful place to be. I didn't think I was up to doing actual research in biology, so for my summer visit to the field of biology I thought I would just hang around the biology lab and "wash dishes," while I watched what they were doing. I went over to the biology lab to tell them my desire, and Bob Edgar, a young post-doc who was sort of in charge there, said he wouldn't let me do that. He said, "You'll have to really do some research, just like a graduate student, and we'll give you a problem to work on." That suited me fine. I took a phage course, which told us how to do research with bacteriophages (a phage is a virus that contains DNA and attacks bacteria). Right away I found that I was saved a lot of trouble because I knew some physics and mathematics. I knew how atoms worked in liquids, so there was nothing mysterious about how the centrifuge worked. I knew enough statistics to understand the statistical errors in counting little spots in a dish. So while all the biology guys were trying to understand these "new" things, I could spend my time learning the biology part. There was one useful lab technique I learned in that course which I still use today. They taught us how to hold a test tube and take its cap off with one hand (you use your middle and index fingers), while leaving the other hand free to do something else (like hold a pipette that you're sucking cyanide up into). Now, I can hold my toothbrush in one hand, and with the other hand, hold the tube of toothpaste, twist the cap off, and put it back on. It had been discovered that phages could have mutations which would affect their ability to attack bacteria, and we were supposed to study those mutations. There were also some phages that would have a second mutation which would reconstitute their ability to attack bacteria. Some phages which mutated back were exactly the same as they were before. Others were not: There was a slight difference in their effect on bacteria -- they would act faster or slower than normal, and the bacteria would grow slower or faster than normal. In other words, there were "back mutations," but they weren't always perfect; sometimes the phage would recover only part of the ability it had lost. Bob Edgar suggested that I do an experiment which would try to find out if the back mutations occurred in the same place on the DNA spiral. With great care and a lot of tedious work I was able to find three examples of back mutations which had occurred very close together -- closer than anything they had ever seen so far -- and which partially restored the phage's ability to function. It was a slow job. It was sort of accidental: You had to wait around until you got a double mutation, which was very rare. I kept trying to think of ways to make a phage mutate more often and how to detect mutations more quickly, but before I could come up with a good technique the summer was over, and I didn't feel like continuing on that problem. However, my sabbatical year was coming up, so I decided to work in the same biology lab but on a different subject. I worked with Matt Meselson to some extent, and then with a nice fella from England named J. D. Smith. The problem had to do with ribosomes, the "machinery" in the cell that makes protein from what we now call messenger RNA. Using radioactive substances, we demonstrated that the RNA could come out of ribosomes and could be put back in. I did a very careful job in measuring and trying to control everything, but it took me eight months to realize that there was one step that was sloppy. In preparing the bacteria, to get the ribosomes out, in those days you ground it up with alumina in a mortar. Everything else was chemical and all under control, but you could never repeat the way you pushed the pestle around when you were grinding the bacteria. So nothing ever came of the experiment. Then I guess I have to tell about the time I tried with Hildegarde Lamfrom to discover whether peas could use the same ribosomes as bacteria. The question was whether the ribosomes of bacteria can manufacture the proteins of humans or other organisms. She had just developed a scheme for getting the ribosomes out of peas and giving them messenger RNA so that they would make pea proteins. We realized that a very dramatic and important question was whether ribosomes from bacteria, when given the peas' messenger RNA, would make pea protein or bacteria protein. It was to be a very dramatic and fundamental experiment. Hildegarde said, "I'll need a lot of ribosomes from bacteria." Meselson and I had extracted enormous quantities of ribosomes from E. coli for some other experiment. I said, "Hell, I'll just give you the ribosomes we've got. We have plenty of them in my refrigerator at the lab." It would have been a fantastic and vital discovery if I had been a good biologist. But I wasn't a good biologist. We had a good idea, a good experiment, the right equipment, but I screwed it up: I gave her infected ribosomes -- the grossest possible error that you could make in an experiment like that. My ribosomes had been in the refrigerator for almost a month, and had become contaminated with some other living things. Had I prepared those ribosomes promptly over again and given them to her in a serious and careful way, with everything under control, that experiment would have worked,, and we would have been the first to demonstrate the uniformity of life: the machinery of making proteins, the ribosomes, is the same in every creature. We were there at the right place, we were doing the right things, but I was doing things as an amateur -- stupid and sloppy. You know what it reminds me of? The husband of Madame Bovary in Flaubert's book, a dull country doctor who had some idea of how to fix club feet, and all he did was screw people up. I was similar to that unpracticed surgeon. The other work on the phage I never wrote up -- Edgar kept asking me to write it up, but I never got around to it. That's the trouble with not being in your own field: You don't take it seriously. I did write something informally on it. I sent it to Edgar, who laughed when he read it. It wasn't in the standard form that biologists use -- first, procedures, and so forth. I spent a lot of time explaining things that all the biologists knew. Edgar made a shortened version, but I couldn't understand it. I don't think they ever published it. I never published it directly. Watson thought the stuff I had done with phages was of some interest, so he invited me to go to Harvard. I gave a talk to the biology department about the double mutations which occurred so close together. I told them my guess was that one mutation made a change in the protein, such as changing the pH of an amino acid, while the other mutation made the opposite change on a different amino acid in the same protein, so that it partially balanced the first mutation -- not perfectly, but enough to let the phage operate again. I thought they were two changes in the same protein, which chemically compensated each other. That turned out not to be the case. It was found out a few years later by people who undoubtedly developed a technique for producing and detecting the mutations faster, that what happened was, the first mutation was a mutation in which an entire DNA base was missing. Now the "code" was shifted and could not be "read" any more. The second mutation was either one in which an extra base was put back in, or two more were taken out. Now the code could be read again. The closer the second mutation occurred to the first, the less message would be altered by the double mutation, and the more completely the phage would recover its lost abilities. The fact that there are three "letters" to code each amino acid was thus demonstrated. While I was at Harvard that week, Watson suggested something and we did an experiment together for a few days. It was an incomplete experiment, but I learned some new lab techniques from one of the best men in the field. But that was my big moment: I gave a seminar in the biology department of Harvard! I always do that, get into something and see how far I can go. I learned a lot of things in biology, and I gained a lot of experience. I got better at pronouncing the words, knowing what not to include in a paper or a seminar, and detecting a weak technique in an experiment. But I love physics, and I love to go back to it. -------- Monster Minds While I was still a graduate student at Princeton, I worked as a research assistant under John Wheeler. He gave me a problem to work on, and it got hard, and I wasn't getting anywhere. So I went back to an idea that I had had earlier, at MIT. The idea was that electrons don't act on themselves, they only act on other electrons. There was this problem: When you shake an electron, it radiates energy, and so there's a loss. That means there must be a force on it. And there must be a different force when it's charged than when it's not charged. (If the force were exactly the same when it was charged and not charged, in one case it would lose energy, and in the other it wouldn't. You can't have two different answers to the same problem.) The standard theory was that it was the electron acting on itself that made that force (called the force of radiation reaction), and I had only electrons acting on other electrons. So I was in some difficulty, I realized, by that time. (When I was at MIT, I got the idea without noticing the problem, but by the time I got to Princeton, I knew that problem.) What I thought was: I'll shake this electron. It will make some nearby electron shake, and the effect back from the nearby electron would be the origin of the force of radiation reaction. So I did some calculations and took them to Wheeler. Wheeler, right away, said, "Well, that isn't right because it varies inversely as the square of the distance of the other electrons, whereas it should not depend on any of these variables at all. It'll also depend inversely upon the mass of the other electron; it'll be proportional to the charge on the other electron." What bothered me was, I thought he must have done the calculation. I only realized later that a man like Wheeler could immediately see all that stuff when you give him the problem. I had to calculate, but he could see. Then he said, "And it'll be delayed -- the wave returns late -- so all you've described is reflected light." "Oh! Of course," I said. "But wait," he said. "Let's suppose it returns by advanced waves -- reactions backward in time -- so it comes back at the right time. We saw the effect varied inversely as the square of the distance, but suppose there are a lot of electrons, all over space: the number is proportional to the square of the distance. So maybe we can make it all compensate." We found out we could do that. It came out very nicely, and fit very well. It was a classical theory that could be right, even though it differed from Maxwell's standard, or Lorentz's standard theory. It didn't have any trouble with the infinity of self-action, and it was ingenious. It had actions and delays, forwards and backwards in time -- we called it "half-advanced and half-retarded potentials." Wheeler and I thought the next problem was to turn to the quantum theory of electrodynamics, which had difficulties (I thought) with the self-action of the electron. We figured if we could get rid of the difficulty first in classical physics, and then make a quantum theory out of that, we could straighten out the quantum theory as well. Now that we had got the classical theory right, Wheeler said, "Feynman, you're a young fella -- you should give a seminar on this. You need experience in giving talks. Meanwhile, I'll work out the quantum theory part and give a seminar on that later." So it was to be my first technical talk, and Wheeler made arrangements with Eugene Wigner to put it on the regular seminar schedule. A day or two before the talk I saw Wigner in the hall. "Feynman," he said, "I think that work you're doing with Wheeler is very interesting, so I've invited Russell to the seminar." Henry Norris Russell, the famous, great astronomer of the day, was coming to the lecture! Wigner went on. "I think Professor von Neumann would also be interested." Johnny von Neumann was the greatest mathematician around. "And Professor Pauli is visiting from Switzerland, it so happens, so I've invited Professor Pauli to come" -- Pauli was a very famous physicist -- and by this time, I'm turning yellow. Finally, Wigner said, "Professor Einstein only rarely comes to our weekly seminars, but your work is so interesting that I've invited him specially, so he's coming, too." By this time I must have turned green, because Wigner said, "No, no! Don't worry! I'll just warn you, though: If Professor Russell falls asleep -- and he will undoubtedly fall asleep -- it doesn't mean that the seminar is bad; he falls asleep in all the seminars. On the other hand, if Professor Pauli is nodding all the time, and seems to be in agreement as the seminar goes along, pay no attention. Professor Pauli has palsy." I went back to Wheeler and named all the big, famous people who were coming to the talk he got me to give, and told him I was uneasy about it. "It's all right," he said. "Don't worry. I'll answer all the questions." So I prepared the talk, and when the day came, I went in and did something that young men who have had no experience in giving talks often do -- I put too many equations up on the blackboard. You see, a young fella doesn't know how to say, "Of course, that varies inversely, and this goes this way..." because everybody listening already knows; they can see it. But he doesn't know. He can only make it come out by actually doing the algebra -- and therefore the reams of equations. As I was writing these equations all over the blackboard ahead of time, Einstein came in and said pleasantly, "Hello, I'm coming to your seminar. But first, where is the tea?" I told him, and continued writing the equations. Then the time came to give the talk, and here are these monster minds in front of me, waiting! My first technical talk -- and I have this audience! I mean they would put me through the wringer! I remember very clearly seeing my hands shaking as they were pulling out my notes from a brown envelope. But then a miracle occurred, as it has occurred again and again in my life, and it's very lucky for me: the moment I start to think about the physics, and have to concentrate on what I'm explaining, nothing else occupies my mind -- I'm completely immune to being nervous. So after I started to go, I just didn't know who was in the room. I was only explaining this idea, that's all. But then the end of the seminar came, and it was time for questions. First off, Pauli, who was sitting next to Einstein, gets up and says, "I do not sink dis teory can be right, because of dis, and dis, and dis," and he turns to Einstein and says, "Don't you agree, Professor Einstein?" Einstein says, "Nooooooooooooo," a nice, German-sounding "No," -- very polite. "I find only that it would be very difficult to make a corresponding theory for gravitational interaction." He meant for the general theory of relativity, which was his baby. He continued: "Since we have at this time not a great deal of experimental evidence, I am not absolutely sure of the correct gravitational theory." Einstein appreciated that things might be different from what his theory stated; he was very tolerant of other ideas. I wish I had remembered what Pauli said, because I discovered years later that the theory was not satisfactory when it came to making the quantum theory. It's possible that that great man noticed the difficulty immediately and explained it to me in the question, but I was so relieved at not having to answer the questions that I didn't really listen to them carefully. I do remember walking up the steps of Palmer Library with Pauli, who said to me, "What is Wheeler going to say about the quantum theory when he gives his talk?" I said, "I don't know. He hasn't told me. He's working it out himself." "Oh?" he said. "The man works and doesn't tell his assistant what he's doing on the quantum theory?" He came closer to me and said in a low, secretive voice, "Wheeler will never give that seminar." And it's true. Wheeler didn't give the seminar. He thought it would be easy to work out the quantum part; he thought he had it, almost. But he didn't. And by the time the seminar came around, he realized he didn't know how to do it, and therefore didn't have anything to say. I never solved it, either -- a quantum theory of half-advanced, half-retarded potentials -- and I worked on it for years. -------- Mixing Paints The reason why I say I'm "uncultured" or "anti-intellectual" probably goes all the way back to the time when I was in high school. I was always worried about being a sissy; I didn't want to be too delicate. To me, no real man ever paid any attention to poetry and such things. How poetry ever got written -- that never struck me! So I developed a negative attitude toward the guy who studies French literature, or studies too much music or poetry -- all those "fancy" things. I admired better the steel-worker, the welder, or the machine shop man. I always thought the guy who worked in the machine shop and could make things, now he was a real guy! That was my attitude. To be a practical man was, to me, always somehow a positive virtue, and to be "cultured" or "intellectual" was not. The first was right, of course, but the second was crazy. I still had this feeling when I was doing my graduate study at Princeton, as you'll see. I used to eat often in a nice little restaurant called Papa's Place. One day, while I was eating there, a painter in his painting clothes came down from an upstairs room he'd been painting, and sat near me. Somehow we struck up a conversation and he started talking about how you've got to learn a lot to be in the painting business. "For example," he said, "in this restaurant, what colors would you use to paint the walls, if you had the job to do?" I said I didn't know, and he said, "You have a dark band up to such-and-such a height, because, you see, people who sit at the tables rub their elbows against the walls, so you don't want a nice, white wall there. It gets dirty too easily. But above that, you do want it white to give a feeling of cleanliness to the restaurant." The guy seemed to know what he was doing, and I was sitting there, hanging on his words, when he said, "And you also have to know about colors -- how to get different colors when you mix the paint. For example, what colors would you mix to get yellow?" I didn't know how to get yellow by mixing paints. If it's light, you mix green and red, but I knew he was talking paints. So I said, "I don't know how you get yellow without using yellow." "Well," he said, "if you mix red and white, you'll get yellow." "Are you sure you don't mean pink?" "No," he said, "you'll get yellow" -- and I believed that he got yellow, because he was a professional painter, and I always admired guys like that. But I still wondered how he did it. I got an idea. "It must be some kind of chemical change. Were you using some special kind of pigments that make a chemical change?" "No," he said, "any old pigments will work. You go down to the five-and-ten and get some paint -- just a regular can of red paint and a regular can of white paint -- and I'll mix 'em, and I'll show how you get yellow." At this juncture I was thinking, "Something is crazy. I know enough about paints to know you won't get yellow, but he must know that you do get yellow, and therefore something interesting happens. I've got to see what it is!" So I said, "OK, I'll get the paints." The painter went back upstairs to finish his painting job, and the restaurant owner came over and said to me, "What's the idea of arguing with that man? The man is a painter; he's been a painter all his life, and he says he gets yellow. So why argue with him?" I felt embarrassed. I didn't know what to say. Finally I said, "All my life, I've been studying light. And I think that with red and white you can't get yellow -- you can only get pink." So I went to the five-and-ten and got the paint, and brought it back to the restaurant. The painter came down from upstairs, and the restaurant owner was there too. I put the cans of paint on an old chair, and the painter began to mix the paint. He put a little more red, he put a little more white -- it still looked pink to me -- and he mixed some more. Then he mumbled something like, "I used to have a little tube of yellow here to sharpen it up -- a bit -- then this'll be yellow." "Oh!" I said. "Of course! You add yellow, and you can get yellow, but you couldn't do it without the yellow." The painter went back upstairs to paint. The restaurant owner said, "That guy has his nerve, arguing with a guy who's studied light all his life!" But that shows you how much I trusted these "real guys." The painter had told me so much stuff that was reasonable that I was ready to give a certain chance that there was an odd phenomenon I didn't know. I was expecting pink, but my set of thoughts were, "The only way to get yellow will be something new and interesting, and I've got to see this." I've very often made mistakes in my physics by thinking the theory isn't as good as it really is, thinking that there are lots of complications that are going to spoil it -- an attitude that anything can happen, in spite of what you're pretty sure should happen. -------- A Different Box of Tools At the Princeton graduate school, the physics department and the math department shared a common lounge, and every day at four o'clock we would have tea. It was a way of relaxing in the afternoon, in addition to imitating an English college. People would sit around playing Go, or discussing theorems. In those days topology was the big thing. I still remember a guy sitting on the couch, thinking very hard, and another guy standing in front of him, saying, "And therefore such-and-such is true." "Why is that?" the guy on the couch asks. "It's trivial! It's trivial!" the standing guy says, and he rapidly reels off a series of logical steps: "First you assume thus-and-so, then we have Kerchoff's this-and-that; then there's Waffenstoffer's Theorem, and we substitute this and construct that. Now you put the vector which goes around here and then thus-and-so..." The guy on the couch is struggling to understand all this stuff, which goes on at high speed for about fifteen minutes! Finally the standing guy comes out the other end, and the guy on the couch says, "Yeah, yeah. It's trivial." We physicists were laughing, trying to figure them out. We decided that "trivial" means "proved." So we joked with the mathematicians: "We have a new theorem -- that mathematicians can prove only trivial theorems, because every theorem that's proved is trivial." The mathematicians didn't like that theorem, and I teased them about it. I said there are never any surprises -- that the mathematicians only prove things that are obvious. Topology was not at all obvious to the mathematicians. There were all kinds of weird possibilities that were "counterintuitive." Then I got an idea. I challenged them: "I bet there isn't a single theorem that you can tell me -- what the assumptions are and what the theorem is in terms I can understand -- where I can't tell you right away whether it's true or false." It often went like this: They would explain to me, "You've got an orange, OK? Now you cut the orange into a finite number of pieces, put it back together, and it's as big as the sun. True or false?" "No holes?" "No holes." "Impossible! There ain't no such a thing." "Ha! We got him! Everybody gather around! It's So-and-so's theorem of immeasurable measure!" Just when they think they've got me, I remind them, "But you said an orange! You can't cut the orange peel any thinner than the atoms." "But we have the condition of continuity: We can keep on cutting!" "No, you said an orange, so I assumed that you meant a real orange." So I always won. If I guessed it right, great. If I guessed it wrong, there was always something I could find in their simplification that they left out. Actually, there was a certain amount of genuine quality to my guesses. I had a scheme, which I still use today when somebody is explaining something that I'm trying to understand: I keep making up examples. For instance, the mathematicians would come in with a terrific theorem, and they're all excited. As they're telling me the conditions of the theorem, I construct something which fits all the conditions. You know, you have a set (one ball) -- disjoint (two balls). Then the balls turn colors, grow hairs, or whatever, in my head as they put more conditions on. Finally they state the theorem, which is some dumb thing about the ball which isn't true for my hairy green ball thing, so I say, "False!" If it's true, they get all excited, and I let them go on for a while. Then I point out my counterexample. "Oh. We forgot to tell you that it's Class 2 Hausdorff homomorphic." "Well, then," I say, "It's trivial! It's trivial!" By that time I know which way it goes, even though I don't know what Hausdorff homomorphic means. I guessed right most of the time because although the mathematicians thought their topology theorems were counterintuitive, they weren't really as difficult as they looked. You can get used to the funny properties of this ultra-fine cutting business and do a pretty good job of guessing how it will come out. Although I gave the mathematicians a lot of trouble, they were always very kind to me. They were a happy bunch of boys who were developing things, and they were terrifically excited about it. They would discuss their "trivial" theorems, and always try to explain something to you if you asked a simple question. Paul Olum and I shared a bathroom. We got to be good friends, and he tried to teach me mathematics. He got me up to homotopy groups, and at that point I gave up. But the things below that I understood fairly well. One thing I never did learn was contour integration. I had learned to do integrals by various methods shown in a book that my high school physics teacher Mr. Bader had given me. One day he told me to stay after class. "Feynman," he said, "you talk too much and you make too much noise. I know why. You're bored. So I'm going to give you a book. You go up there in the back, in the corner, and study this book, and when you know everything that's in this book, you can talk again." So every physics class, I paid no attention to what was going on with Pascal's Law, or whatever they were doing. I was up in the back with this book: Advanced Calculus, by Woods. Bader knew I had studied Calculus for the Practical Man a little bit, so he gave me the real works -- it was for a junior or senior course in college. It had Fourier series, Bessel functions, determinants, elliptic functions -- all kinds of wonderful stuff that I didn't know anything about. That book also showed how to differentiate parameters under the integral sign -- it's a certain operation. It turns out that's not taught very much in the universities; they don't emphasize it. But I caught on how to use that method, and I used that one damn tool again and again. So because I was self-taught using that book, I had peculiar methods of doing integrals. The result was, when guys at MIT or Princeton had trouble doing a certain integral, it was because they couldn't do it with the standard methods they had learned in school. If it was contour integration, they would have found it; if it was a simple series expansion, they would have found it. Then I come along and try differentiating under the integral sign, and often it worked. So I got a great reputation for doing integrals, only because my box of tools was different from everybody else's, and they had tried all their tools on it before giving the problem to me. -------- Mindreaders My father was always interested in magic and carnival tricks, and wanting to see how they worked. One of the things he knew about was mindreaders. When he was a little boy, growing up in a small town called Patchogue, in the middle of Long Island, it was announced on advertisements posted all over that a mindreader was coming next Wednesday. The posters said that some respected citizens -- the mayor, a judge, a banker -- should take a five-dollar bill and hide it somewhere, and when the mindreader came to town, he would find it. When he came, the people gathered around to watch him do his work. He takes the hands of the banker and the judge, who had hidden the five-dollar bill, and starts to walk down the street. He gets to an intersection, turns the corner, walks down another street, then another, to the correct house. He goes with them, always holding their hands, into the house, up to the second floor, into the right room, walks up to a bureau, lets go of their hands, opens the correct drawer, and there's the five-dollar bill. Very dramatic! In those days it was difficult to get a good education, so the mindreader was hired as a tutor for my father. Well, my father, after one of his lessons, asked the mindreader how he was able to find the money without anyone telling him where it was. The mindreader explained that you hold onto their hands, loosely, and as you move, you jiggle a little bit. You come to an intersection, where you can go forward, to the left, or to the right. You jiggle a little bit to the left, and if it's incorrect, you feel a certain amount of resistance, because they don't expect you to move that way. But when you move in the right direction, because they think you might be able to do it, they give way more easily, and there's no resistance. So you must always be jiggling a little bit, testing out which seems to be the easiest way. My father told me the story and said he thought it would still take a lot of practice. He never tried it himself. Later, when I was doing graduate work at Princeton, I decided to try it on a fellow named Bill Woodward. I suddenly announced that I was a mindreader, and could read his mind. I told him to go into the "laboratory" -- a big room with rows of tables covered with equipment of various kinds, with electric circuits, tools, and junk all over the place -- pick out a certain object, somewhere, and come out. I explained, "Now I'll read your mind and take you right up to the object." He went into the lab, noted a particular object, and came out. I took his hand and started jiggling. We went down this aisle, then that one, right to the object. We tried it three times. One time I got the object right on -- and it was in the middle of a whole bunch of stuff. Another time I went to the right place but missed the object by a few inches -- wrong object. The third time, something went wrong. But it worked better than I thought. It was very easy. Some time after that, when I was about twenty-six or so, my father and I went to Atlantic City, where they had various carnival things going on outdoors. While my father was doing some business, I went to see a mindreader. He was seated on the stage with his back to the audience, dressed in robes and wearing a great big turban. He had an assistant, a little guy who was running around through the audience, saying things like, "Oh, Great Master, what is the color of this pocketbook?" "Blue!" says the master. "And oh, Illustrious Sir, what is the name of this woman?" "Marie!" Some guy gets up: "What's my name?" "Henry." I get up and say, "What's my name?" He doesn't answer. The other guy was obviously a confederate, but I couldn't figure out how the mindreader did the other tricks, like telling the color of the pocketbook. Did he wear earphones underneath the turban? When I met up with my father, I told him about it. He said, "They have a code worked out, but I don't know what it is. Let's go back and find out." We went back to the place, and my father said to me, "Here's fifty cents. Go get your fortune read in the booth back there, and I'll see you in half an hour." I knew what he was doing. He was going to tell the man a story, and it would go smoother if his son wasn't there going, "Ooh, ooh!" all the time. He had to get me out of the way. When he came back he told me the whole code: "Blue is 'Oh, Great Master,' Green is 'Oh, Most Knowledgeable One,'" and so forth. He explained, "I went up to him, afterwards, and told him I used to do a show in Patchogue, and we had a code, but it couldn't do many numbers, and the range of colors was shorter. I asked him, 'How do you carry so much information?'" The mindreader was so proud of his code that he sat down and explained the whole works to my father. My father was a salesman. He could set up a situation like that. I can't do stuff like that. -------- The Amateur Scientist When I was a kid I had a "lab." It wasn't a laboratory in the sense that I would measure, or do important experiments. Instead, I would play: I'd make a motor, I'd make a gadget that would go off when something passed a photocell. I'd play around with selenium; I was piddling around all the time. I did calculate a little bit for the lamp bank, a series of switches and bulbs I used as resistors to control voltages. But all that was for application. I never did any laboratory kind of experiments. I also had a microscope and loved to watch things under the microscope. It took patience: I would get something under the microscope and I would watch it interminably. I saw many interesting things, like everybody sees -- a diatom slowly making its way across the slide, and so on. One day I was watching a paramecium and I saw something that was not described in the books I got in school -- in college, even. These books always simplify things so the world will be more like they want it to be: When they're talking about the behavior of animals, they always start out with, "The paramecium is extremely simple; it has a simple behavior. It turns as its slipper shape moves through the water until it hits something, at which time it recoils, turns through an angle, and then starts out again." It isn't really right. First of all, as everybody knows, the paramecia, from time to time, conjugate with each other -- they meet and exchange nuclei. How do they decide when it's time to do that? (Never mind; that's not my observation.) I watched these paramecia hit something, recoil, turn through an angle, and go again. The idea that it's mechanical, like a computer program -- it doesn't look that way. They go different distances, they recoil different distances, they turn through angles that are different in various cases; they don't always turn to the right; they're very irregular. It looks random, because you don't know what they're hitting; you don't know all the chemicals they're smelling, or what. One of the things I wanted to watch was what happens to the paramecium when the water that it's in dries up. It was claimed that the paramecium can dry up into a sort of hardened seed. I had a drop of water on the slide under my microscope, and in the drop of water was a paramecium and some "grass" -- at the scale of the paramecium, it looked like a network of jackstraws. As the drop of water evaporated, over a time of fifteen or twenty minutes, the paramecium got into a tighter and tighter situation: there was more and more of this back-and-forth until it could hardly move. It was stuck between these "sticks," almost jammed. Then I saw something I had never seen or heard of: the paramecium lost its shape. It could flex itself, like an amoeba. It began to push itself against one of the sticks, and began dividing into two prongs until the division was about halfway up the paramecium, at which time it decided that wasn't a very good idea, and backed away. So my impression of these animals is that their behavior is much too simplified in the books. It is not so utterly mechanical or one-dimensional as they say. They should describe the behavior of these simple animals correctly. Until we see how many dimensions of behavior even a one-celled animal has, we won't be able to fully understand the behavior of more complicated animals. I also enjoyed watching bugs. I had an insect book when I was about thirteen. It said that dragonflies are not harmful; they don't sting. In our neighborhood it was well known that "darning needles," as we called them, were very dangerous when they'd sting. So if we were outside somewhere playing baseball, or something, and one of these things would fly around, everybody would run for cover, waving their arms, yelling, "A darning needle! A darning needle!" So one day I was on the beach, and I'd just read this book that said dragonflies don't sting. A darning needle came along, and everybody was screaming and running around, and I just sat there. "Don't worry!" I said. "Darning needles don't sting!" The thing landed on my foot. Everybody was yelling and it was a big mess, because this darning needle was sitting on my foot. And there I was, this scientific wonder, saying it wasn't going to sting me. You're sure this is a story that's going to come out that it stings me -- but it didn't. The book was right. But I did sweat a bit. I also had a little hand microscope. It was a toy microscope, and I pulled the magnification piece out of it, and would hold it in my hand like a magnifying glass, even though it was a microscope of forty or fifty power. With care you could hold the focus. So I could go around and look at things right out in the street. So when I was in graduate school at Princeton, I once took it out of my pocket to look at some ants that were crawling around on some ivy. I had to exclaim out loud, I was so excited. What I saw was an ant and an aphid, which ants take care of -- they carry them from plant to plant if the plant they're on is dying. In return the ants get partially digested aphid juice, called "honeydew." I knew that; my father had told me about it, but I had never seen it. So here was this aphid and sure enough, an ant came along, and patted it with its feet -- all around the aphid, pat, pat, pat, pat, pat. This was terribly exciting! Then the juice came out of the back of the aphid. And because it was magnified, it looked like a big, beautiful, glistening ball, like a balloon, because of the surface tension. Because the microscope wasn't very good, the drop was colored a little bit from chromatic aberration in the lens -- it was a gorgeous thing! The ant took this ball in its two front feet, lifted it off the aphid, and held it. The world is so different at that scale that you can pick up water and hold it! The ants probably have a fatty or greasy material on their legs that doesn't break the surface tension of the water when they hold it up. Then the ant broke the surface of the drop with its mouth, and the surface tension collapsed the drop right into his gut. It was very interesting to see this whole thing happen! In my room at Princeton I had a bay window with a U-shaped windowsill. One day some ants came out on the windowsill and wandered around a little bit. I got curious as to how they found things. I wondered, how do they know where to go? Can they tell each other where food is, like bees can? Do they have any sense of geometry? This is all amateurish; everybody knows the answer, but I didn't know the answer, so the first thing I did was to stretch some string across the U of the bay window and hang a piece of folded cardboard with sugar on it from the string. The idea of this was to isolate the sugar from the ants, so they wouldn't find it accidentally. I wanted to have everything under control. Next I made a lot of little strips of paper and put a fold in them, so I could pick up ants and ferry them from one place to another. I put the folded strips of paper in two places: Some were by the sugar (hanging from the string), and the others were near the ants in a particular location. I sat there all afternoon, reading and watching, until an ant happened to walk onto one of my little paper ferries. Then I took him over to the sugar. After a few ants had been ferried over to the sugar, one of them accidentally walked onto one of the ferries nearby, and I carried him back. I wanted to see how long it would take the other ants to get the message to go to the "ferry terminal." It started slowly, but rapidly increased until I was going mad ferrying the ants back and forth. But suddenly, when everything was going strong, I began to deliver the ants from the sugar to a different spot. The question now was, does the ant learn to go back to where it just came from, or does it go where it went the time before? After a while there were practically no ants going to the first place (which would take them to the sugar), whereas there were many ants at the second place, milling around, trying to find the sugar. So I figured out so far that they went where they just came from. In another experiment, I laid out a lot of glass microscope slides, and got the ants to walk on them, back and forth, to some sugar I put on the windowsill. Then, by replacing an old slide with a new one, or by rearranging the slides, I could demonstrate that the ants had no sense of geometry: they couldn't figure out where something was. If they went to the sugar one way, and there was a shorter way back, they would never figure out the short way. It was also pretty clear from rearranging the glass slides that the ants left some sort of trail. So then came a lot of easy experiments to find out how long it takes a trail to dry up, whether it can be easily wiped off, and so on. I also found out the trail wasn't directional. If I'd pick up an ant on a piece of paper, turn him around and around, and then put him back onto the trail, he wouldn't know that he was going the wrong way until he met another ant. (Later, in Brazil, I noticed some leaf-cutting ants and tried the same experiment on them. They could tell, within a few steps, whether they were going toward the food or away from it -- presumably from the trail, which might be a series of smells in a pattern: A, B, space, A, B, space, and so on.) I tried at one point to make the ants go around in a circle, but I didn't have enough patience to set it up. I could see no reason, other than lack of patience, why it couldn't be done. One thing that made experimenting difficult was that breathing on the ants made them scurry. It must be an instinctive thing against some animal that eats them or disturbs them. I don't know if it was the warmth, the moisture, or the smell of my breath that bothered them, but I always had to hold my breath and kind of look to one side so as not to confuse the experiment while I was ferrying the ants. One question that I wondered about was why the ant trails look so straight and nice. The ants look as if they know what they're doing, as if they have a good sense of geometry. Yet the experiments that I did to try to demonstrate their sense of geometry didn't work. Many years later, when I was at Caltech and lived in a little house on Alameda Street, some ants came out around the bathtub. I thought, "This is a great opportunity." I put some sugar on the other end of the bathtub, and sat there the whole afternoon until an ant finally found the sugar. It's only a question of patience. The moment the ant found the sugar, I picked up a colored pencil that I had ready (I had previously done experiments indicating that the ants don't give a damn about pencil marks -- they walk right over them -- so I knew I wasn't disturbing anything), and behind where the ant went I drew a line so I could tell where his trail was. The ant wandered a little bit wrong to get back to the hole, so the line was quite wiggly, unlike a typical ant trail. When the next ant to find the sugar began to go back, I marked his trail with another color. (By the way, he followed the first ant's return trail back, rather than his own incoming trail. My theory is that when an ant has found some food, he leaves a much stronger trail than when he's just wandering around.) This second ant was in a great hurry and followed, pretty much, the original trail. But because he was going so fast he would go straight out, as if he were coasting, when the trail was wiggly. Often, as the ant was "coasting," he would find the trail again. Already it was apparent that the second ant's return was slightly straighter. With successive ants the same "improvement" of the trail by hurriedly and carelessly "following" it occurred. I followed eight or ten ants with my pencil until their trails became a neat line right along the bathtub. It's something like sketching: You draw a lousy line at first; then you go over it a few times and it makes a nice line after a while. I remember that when I was a kid my father would tell me how wonderful ants are, and how they cooperate. I would watch very carefully three or four ants carrying a little piece of chocolate back to their nest. At first glance it looks like efficient, marvelous, brilliant cooperation. But if you look at it carefully, you'll see that it's nothing of the kind: They're all behaving as if the chocolate is held up by something else. They pull at it one way or the other way. An ant may crawl over it while it's being pulled at by the others. It wobbles, it wiggles, the directions are all confused. The chocolate doesn't move in a nice way toward the nest. The Brazilian leaf-cutting ants, which are otherwise so marvelous, have a very interesting stupidity associated with them that I'm surprised hasn't evolved out. It takes considerable work for the ant to cut the circular arc in order to get a piece of leaf. When the cutting is done, there's a fifty-fifty chance that the ant will pull on the wrong side, letting the piece he just cut fall to the ground. Half the time, the ant will yank and pull and yank and pull on the wrong part of the leaf, until it gives up and starts to cut another piece. There is no attempt to pick up a piece that it, or any other ant, has already cut. So it's quite obvious, if you watch very carefully, that it's not a brilliant business of cutting leaves and carrying them away; they go to a leaf, cut an arc, and pick the wrong side half the time while the right piece falls down. In Princeton the ants found my larder, where I had jelly and bread and stuff, which was quite a distance from the window. A long line of ants marched along the floor across the living room. It was during the time I was doing these experiments on the ants, so I thought to myself, "What can I do to stop them from coming to my larder without killing any ants? No poison; you gotta be humane to the ants!" What I did was this: In preparation, I put a bit of sugar about six or eight inches from their entry point into the room, that they didn't know about. Then I made those ferry things again, and whenever an ant returning with food walked onto my little ferry, I'd carry him over and put him on the sugar. Any ant coming toward the larder that walked onto a ferry I also carried over to the sugar. Eventually the ants found their way from the sugar to their hole, so this new trail was being doubly reinforced, while the old trail was being used less and less. I knew that after half an hour or so the old trail would dry up, and in an hour they were out of my larder. I didn't wash the floor; I didn't do anything but ferry ants.
