Surely You're Joking, Mr. Feynman! (12 page)

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.

Feynman, the Bomb, and the Military

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Fizzled Fuses
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When the war began in Europe but had not yet been declared in the United States, there was a lot of talk about getting ready and being patriotic. The newspapers had big articles on businessmen volunteering to go to Plattsburg, New York, to do military training, and so on.

I began to think I ought to make some kind of contribution, too. After I finished up at MIT, a friend of mine from the fraternity, Maurice Meyer, who was in the Army Signal Corps, took me to see a colonel at the Signal Corps offices in New York.

“I’d like to aid my country sir, and since I’m technicallyminded, maybe there’s a way I could help.”

“Well, you’d better just go up to Plattsburg to boot camp and go through basic training. Then we’ll be able to use you,” the colonel said.

“But isn’t there some way to use my talent more directly?”

“No; this is the way the army is organized. Go through the regular way.”

I went outside and sat in the park to think about it. I thought and thought: Maybe the best way to make a contribution is to go along with their way. But fortunately I thought a little more, and said, “To hell with it! I’ll wait awhile. Maybe something will happen where they can use me more effectively”

I went to Princeton to do graduate work, and in the spring I went once again to the Bell Labs in New York to apply for a summer job. I loved to tour the Bell Labs. Bill Shockley the guy who invented transistors, would show me around. I remember somebody’s room where they had marked a window: The George Washington Bridge was being built, and these guys in the lab were watching its progress. They had plotted the original curve when the main cable was first put up, and they could measure the small differences as the bridge was being suspended from it, as the curve turned into a parabola. It was just the kind of thing I would like to be able to think of doing. I admired those guys; I was always hoping I could work with them one day.

Some guys from the lab took me out to this seafood restaurant for lunch, and they were all pleased that they were going to have oysters. I lived by the ocean and I couldn’t look at this stuff; I couldn’t eat fish, let alone oysters.

I thought to myself, “I’ve gotta be brave. I’ve gotta eat an oyster.”

I took an oyster, and it was absolutely terrible. But I said to myself, “That doesn’t really prove you’re a man. You didn’t know how terrible it was gonna be. It was easy enough when it was uncertain.”

The others kept talking about how good the oysters were, so I had another oyster, and that was really harder than the first one.

This time, which must have been my fourth or fifth time touring the Bell Labs, they accepted me. I was very happy. In those days it was hard to find a job where you could be with other scientists.

But then there was a big excitement at Princeton. General Trichel from the army came around and spoke to us: “We’ve got to have physicists! Physicists are very important to us in the army! We need three physicists!”

You have to understand that, in those days, people hardly knew what a physicist was. Einstein was known as a mathematician, for instance–so it was rare that anybody needed physicists. I thought, “This is my opportunity to make a contribution,” and I volunteered to work for the army.

I asked the Bell Labs if they would let me work for the army that summer, and they said they had war work, too, if that was what I wanted. But I was caught up in a patriotic fever and lost a good opportunity. It would have been much smarter to work in the Bell Labs. But one gets a little silly during those times.

I went to the Frankfort Arsenal, in Philadelphia, and worked on a dinosaur: a mechanical computer for directing artillery. When airplanes flew by the gunners would watch them in a telescope, and this mechanical computer, with gears and cams and so forth, would try to predict where the plane was going to he. It was a most beautifully designed and built machine, and one of the important ideas in it was non-circular gears–gears that weren’t circular, but would mesh anyway. Because of the changing radii of the gears, one shaft would turn as a function of the other. However, this machine was at the end of the line. Very soon afterwards, electronic computers came in.

After saying all this stuff about how physicists were so important to the army the first thing they had me doing was checking gear drawings to see if the numbers were right. This went on for quite a while. Then, gradually the guy in charge of the department began to see I was useful for other things, and as the summer went on, he would spend more time discussing things with me.

One mechanical engineer at Frankfort was always trying to design things and could never get everything right. One time he designed a box full of gears, one of which was a big, eight-inch-diameter gear wheel that had six spokes. The fella says excitedly “Well, boss, how is it? How is it?”

“Just fine!” the boss replies. “All you have to do is specify a shaft passer on each of the spokes, so the gear wheel can turn!” The guy had designed a shaft that went right between the spokes!

The boss went on to tell us that there _was_ such a thing as a shaft passer (I thought he must have been joking). It was invented by the Germans during the war to keep the British minesweepers from catching the cables that held the German mines floating under water at a certain depth. With these shaft passers, the German cables could allow the British cables to pass through as if they were going through a revolving door. So it _was_ possible to put shaft passers on all the spokes, but the boss didn’t mean that the machinists should go to all that trouble; the guy should instead just redesign it and put the shaft somewhere else.

Every once in a while the army sent down a lieutenant to check on how things were going. Our boss told us that since we were a civilian section, the lieutenant was higher in rank than any of us. “Don’t tell the lieutenant anything,” he said. “Once he begins to think he knows what we’re doing, he’ll be giving us all kinds of orders and screwing everything up.

By that time I was designing some things, but when the lieutenant came by I pretended I didn’t know what I was doing, that I was only following orders.

“What are you doing here, Mr. Feynman?”

“Well, I draw a sequence of lines at successive angles, and then I’m supposed to measure out from the center different distances according to this table, and lay it out.

“Well, what is it?”

“I think it’s a cam.” I had actually designed the thing, but I acted as if somebody had just told me exactly what to do.