Surely You're Joking, Mr. Feynman! (16 page)

He said, “Then you should say: _Los Alamos cannot accept the responsibility for the safety of the Oak Ridge plant_ unless —-!”

I said, “You mean me, little Richard, is going to go in there and say–?”

He said, “Yes, little Richard, you go and do that.”

I really grew up fast!

When I arrived, sure enough, the big shots in the company and the technical people that I wanted were there, and the generals and everyone who was interested in this very serious problem. That was good because the plant would have blown up if nobody had paid attention to this problem.

There was a Lieutenant Zumwalt who took care of me. He told me that the colonel said I shouldn’t tell them how the neutrons work and all the details because we want to keep things separate, so just tell them what to do to keep it safe.

I said, “In my opinion it is impossible for them to obey a bunch of rules unless they understand how it works. It’s my opinion that it’s only going to work if I tell them, and _Los Alamos cannot accept the responsibility for the safety of the Oak Ridge plant unless they are fully informed as to how it works!_”

It was great. The lieutenant takes me to the colonel and repeats my remark. The colonel says, “Just five minutes,” and then he goes to the window and he stops and thinks. That’s what they’re very good at–making decisions. I thought it was very remarkable how a problem of whether or not information as to how the bomb works should be in the Oak Ridge plant had to be decided and _could_ be decided in five minutes. So I have a great deal of respect for these military guys, because I never can decide anything very important in any length of time at all.

In five minutes he said, “All right, Mr. Feynman, go ahead.”

I sat down and I told them all about neutrons, how they worked, da da, ta ta ta, there are too many neutrons together, you’ve got to keep the material apart, cadmium absorbs, and slow neutrons are more effective than fast neutrons, and yak yak–all of which was elementary stuff at Los Alamos, but they had never heard of any of it, so I appeared to be a tremendous genius to them.

The result was that they decided to set up little groups to make their own calculations to learn how to do it. They started to redesign plants, and the designers of the plants were there, the construction designers, and engineers, and chemical engineers for the new plant that was going to handle the separated material.

They told me to come back in a few months, so I came back when the engineers had finished the design of the plant. Now it was for me to look at the plant.

How do you look at a plant that isn’t built yet? I don’t know. Lieutenant Zumwalt, who was always coming around with me because I had to have an escort everywhere, takes me into this room where there are these two engineers and a _loooooong_ table covered with a stack of blueprints representing the various floors of the proposed plant.

I took mechanical drawing when I was in school, but I am not good at reading blueprints. So they unroll the stack of blueprints and start to explain it to me, thinking I am a genius. Now, one of the things they had to avoid in the plant was accumulation. They had problems like when there’s an evaporator working, which is trying to accumulate the stuff, if the valve gets stuck or something like that and too much stuff accumulates, it’ll explode. So they explained to me that this plant is designed so that if any one valve gets stuck nothing will happen. It needs at least two valves everywhere.

Then they explain how it works. The carbon tetrachloride comes in here, the uranium nitrate from here comes in here, it goes up and down, it goes up through the floor, comes up through the pipes, coming up from the second floor, _bluuuuurp_–going through the stack of blueprints, downup-down-up, talking very fast, explaining the very very complicated chemical plant.

I’m completely dazed, Worse, I don’t know what the symbols on the blueprint mean! There is some kind of a thing that at first I think is a window. It’s a square with a little cross in the middle, all over the damn place. I think it’s a window, but no, it can’t be a window, because it isn’t always at the edge. I want to ask them what it is.

You must have been in a situation like this when you didn’t ask them right away. Right away it would have been OK. But now they’ve been talking a little bit too long. You hesitated too long. If you ask them now they’ll say “What are you wasting my time all this time for?”

What am I going to _do_? I get an idea. Maybe it’s a valve.

I take my finger and I put it down on one of the mysterious little crosses in the middle of one of the blueprints on page three, and I say “What happens if this valve gets stuck?” –figuring they’re going to say “That’s not a valve, sir, that’s a window.”

So one looks at the other and says, “Well, if _that_ valve gets stuck–” and he goes up and down on the blueprint, up and down, the other guy goes up and down, back and forth, back and forth, and they both look at each other. They turn around to me and they open their mouths like astonished fish and say “You’re absolutely right, sir.”

So they rolled up the blueprints and away they went and we walked out. And Mr. Zumwalt, who had been following me all the way through, said, “You’re a genius. I got the idea you were a genius when you went through the plant once and you could tell them about evaporator C-21 in building 90-207 the next morning,” he says, “but what you have just done is so _fantastic_ I want to know how, _how_ do you do that?”

I told him you try to find out whether it’s a valve or not.

Another kind of problem I worked on was this. We had to do lots of calculations, and we did them on Marchant calculating machines. By the way, just to give you an idea of what Los Alamos was like: We had these Marchant computers– hand calculators with numbers. You push them, and they multiply divide, add, and so on, but not easy like they do now. They were mechanical gadgets, failing often, and they had to be sent back to the factory to be repaired. Pretty soon you were running out of machines. A few of us started to take the covers off. (We weren’t supposed to. The rules read: “You take the covers off, we cannot be responsible . . .”) So we took the covers off and we got a nice series of lessons on how to fix them, and we got better and better at it as we got more and more elaborate repairs. When we got something too complicated, we sent it back to the factory but we’d do the easy ones and kept the things going. I ended up doing all the computers and there was a guy in the machine shop who took care of typewriters.

Anyway we decided that the big problem–which was to figure out exactly what happened during the bomb’s implosion, so you can figure out exactly how much energy was released and so on–required much more calculating than we were capable of. A clever fellow by the name of Stanley Frankel realized that it could possibly he done on IBM machines. The IBM company had machines for business purposes, adding machines called tabulators for listing sums, and a multiplier that you put cards in and it would take two numbers from a card and multiply them. There were also collators and sorters and so on.

So Frankel figured out a nice program. If we got enough of these machines in a room, we could take the cards and put them through a cycle. Everybody who does numerical calculations now knows exactly what I’m talking about, but this was kind of a new thing then–mass production with machines. We had done things like this on adding machines. Usually you go one step across, doing everything yourself. But this was different–where you go first to the adder, then to the multiplier, then to the adder, and so on. So Frankel designed this system and ordered the machines from the IBM company because we realized it was a good way of solving our problems.

We needed a man to repair the machines, to keep them going and everything. And the army was always going to send this fellow they had, but he was always delayed. Now, we _always_ were in a hurry. _Everything_ we did, we tried to do as quickly as possible. In this particular case, we worked out all the numerical steps that the machines were supposed to do–multiply this, and then do this, and subtract that. Then we worked out the program, but we didn’t have any machine to test it on. So we set up this room with girls in it. Each one had a Marchant: one was the multiplier, another was the adder. This one cubed–all she did was cube a number on an index card and send it to the next girl.

We went through our cycle this way until we got all the bugs out. It turned out that the speed at which we were able to do it was a hell of a lot faster than the other way where every single person did all the steps. We got speed with this system that was the predicted speed for the IBM machine. The only difference is that the IBM machines didn’t get tired and could work three shifts. But the girls got tired after a while.

Anyway we got the bugs out during this process, and finally the machines arrived, but not the repairman. These were some of the most complicated machines of the technology of those days, big things that came partially disassembled, with lots of wires and blueprints of what to do. We went down and we put them together, Stan Frankel and I and another fellow, and we had our troubles. Most of the trouble was the big shots coming in all the time and saying, “You’re going to break something!”

We put them together, and sometimes they would work, and sometimes they were put together wrong and they didn’t work. Finally I was working on some multiplier and I saw a bent part inside, but I was afraid to straighten it because it might snap off–and they were always telling us we were going to bust something irreversibly. When the repairman finally got there, he fixed the machines we hadn’t got ready and everything was going. But he had trouble with the one that I had had trouble with. After three days he was still working on that _one_ last machine.

I went down. I said, “Oh, I noticed that was bent.”

He said, “Oh, of course. That’s all there is to it!” _Bend!_ It was all right. So that was it.

Well, Mr. Frankel, who started this program, began to suffer from the computer disease that anybody who works with computers now knows about. It’s a very serious disease and it interferes completely with the work. The trouble with computers is you _play_ with them. They are so wonderful. You have these switches–if it’s an even number you do this, if it’s an odd number you do that–and pretty soon you can do more and more elaborate things if you are clever enough, on one machine.

After a while the whole system broke down. Frankel wasn’t paying any attention; he wasn’t supervising anybody. The system was going very, very slowly–while he was sitting in a room figuring out how to make one tabulator automatically print arc-tangent X, and then it would start and it would print columns and then _bitsi, bitsi, bitsi_, and calculate the arc-tangent automatically by integrating as it went along and make a whole table in one operation.

Absolutely useless. We _had_ tables of arc-tangents. But if you’ve ever worked with computers, you understand the disease–the _delight_ in being able to see how much you can do. But he got the disease for the first time, the poor fellow who invented the thing.

I was asked to stop working on the stuff I was doing in my group and go down and take over the IBM group, and I tried to avoid the disease. And, although they had done only three problems in nine months, I had a very good group.

The real trouble was that no one had ever told these fellows anything. The army had selected them from all over the country for a thing called Special Engineer Detachment– clever boys from high school who had engineering ability. They sent them up to Los Alamos. They put them in barracks. And they would tell them _nothing_.

Then they came to work, and what they had to do was work on IBM machines–punching holes, numbers that they didn’t understand. Nobody told them what it was. The thing was going very slowly. I said that the first thing there has to be is. that these technical guys know what we’re doing. Oppenheimer went and talked to the security and got special permission so I could give a nice lecture about what we were doing, and they were all excited: “We’re fighting a war! We see what it is!” They knew what the numbers meant. If the pressure came out higher, that meant there was more energy released, and so on and so on. They knew what they were doing.

_Complete_ transformation! _They_ began to invent ways of doing it better. They improved the scheme. They worked at night. They didn’t need supervising in the night; they didn’t need anything. They understood everything; they invented several of the programs that we used.

So my boys really came through, and all that had to be done was to tell them what it was. As a result, although it took them nine months to do three problems before, we did nine problems in _three_ months, which is nearly ten times as fast.

But one of the secret ways we did our problems was this. The problems consisted of a hunch of cards that had to go through a cycle. First add, then multiply–and so it went through the cycle of machines in this room, slowly, as it went around and around. So we figured a way to put a different colored set of cards through a cycle too, but out of phase. We’d do two or three problems at a time.

But this got us into _another_ problem. Near the end of the war, for instance, just before we had to make a test in Albuquerque, the question was: How much energy would be released? We had been calculating the release from various designs, but we hadn’t computed for the specific design that was ultimately used. So Bob Christy came down and said, “We would like the results for how this thing is going to work in one month”–or some very short time, like three weeks.

I said, “It’s impossible.”

He said, “Look, you’re putting out nearly two problems a month. It takes only two weeks per problem, or three weeks per problem.”

I said, “I know. It really takes much longer to do the problem, but we’re doing them in _parallel_. As they go through, it takes a long time and there’s no way to make it go around faster.”

He went out, and I began to think. Is there a way to make it go around faster? What if we did nothing else on the machine, so nothing else was interfering? I put a challenge to the boys on the blackboard–CAN WE DO IT? They all start yelling, “Yes, we’ll work double shifts, we’ll work overtime,” all this kind of thing. “We’ll _try_ it. We’ll _try_ it!”