Archdave's Feynman Pages

by Richard P. Feynman

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"Surely You're Joking, Mr. Feynman!"

        by Richard P. Feynman

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Part 3

Feynman, the Bomb, and the Military


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Fizzled Fuses

     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  technically-minded,
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 be. 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.
     The lieutenant  couldn't get any information from anybody,  and we went
happily   along,   working  on  this  mechanical   computer,   without   any
interference.
     One  day the  lieutenant  came  by,  and  asked  us a  simple question:
"Suppose that the observer is not at the same  location as the gunner -- how
do you handle that?"
     We got a terrible shock. We had designed the whole business using polar
coordinates, using angles and the radius distance. With X and Y coordinates,
it's easy to correct  for  a  displaced observer.  It's simply  a matter  of
addition or subtraction. But with polar coordinates, it's a terrible mess!
     So it turned out that this lieutenant whom we were trying  to keep from
telling us anything ended up telling us something very important that we had
forgotten in the design of this device: the possibility that the gun and the
observing station are not at  the same  place! It was a big mess  to fix it.
Near the end of the summer I  was given my first  real design job: a machine
that  would  make a continuous curve out  of a set of  points  --  one point
coming in every fifteen seconds -- from a new invention developed in England
for  tracking airplanes, called "radar."  It was the  first  time I had ever
done any mechanical designing, so I was a little bit frightened.
     I went over  to one of the other  guys and  said, "You're a  mechanical
engineer; I don't know how  to do any mechanical engineering, and I just got
this job..."
     "There's nothin' to it," he  said.  "Look, I'll  show  you. There's two
rules you  need to  know to  design these machines. First,  the friction  in
every bearing is so-and-so much, and in every gear junction, so-and-so much.
From that,  you can figure out how  much force you need to drive  the thing.
Second,  when you  have a  gear  ratio, say  2 to  1, and  you are wondering
whether you should make  it 10 to 5 or 24 to  12  or 48 to 24, here's how to
decide:  You look in the Boston Gear Catalogue, and select those gears  that
are in the middle of the  list. The ones at the high end have  so many teeth
they're hard to make, if they could make gears with even finer teeth, they'd
have made the list go even higher. The gears at the low end of the list have
so few teeth they break  easy. So the best design uses gears from the middle
of the list."
     I had a  lot of fun designing  that machine.  By simply  selecting  the
gears from the middle of the list and adding up the little torques  with the
two numbers he gave me, I could be a mechanical engineer!
     The army didn't want me to go  back to Princeton to work  on my  degree
after that summer.  They kept giving me this patriotic  stuff, and offered a
whole project that I could run, if I would stay.
     The  problem was  to design a machine like the  other one --  what they
called a director -- but this time I thought the problem was easier, because
the  gunner  would be  following  behind  in  another airplane  at the  same
altitude. The gunner would  set into my machine his altitude and an estimate
of  his distance behind the other airplane.  My  machine would automatically
tilt the gun up at the correct angle and set the fuse.
     As director  of this project, I would be  making trips down to Aberdeen
to get the firing tables. However, they already had some preliminary data. I
noticed that for most of the higher altitudes where these airplanes would be
flying, there wasn't  any  data. So I called up to find out why there wasn't
any  data and it turned out that the fuses  they were  going to use were not
clock fuses, but powder-train fuses, which didn't work at those altitudes --
they fizzled out in the thin air.
     I  thought  I  only  had  to  correct the air  resistance  at different
altitudes. Instead, my job was to invent a machine that would make the shell
explode at the right moment, when the fuse won't burn!
     I decided that was too hard for me and went back to Princeton.


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Testing Bloodhounds

     When I was at Los Alamos and would get a little time off, I would often
go visit my wife, who  was in a  hospital in Albuquerque, a few  hours away.
One time I went to visit her and couldn't go in right away, so I went to the
hospital library to read.
     I read an  article  in Science  about  bloodhounds, and  how they could
smell so very well. The authors  described the various experiments that they
did  --  the  bloodhounds could  identify which  items  had  been touched by
people, and so on -- and I began to think:  It  is very remarkable how  good
bloodhounds are  at smelling, being able to follow trails of people, and  so
forth, but how good are we, actually?
     When the time came that I could visit my wife, I went to see her, and I
said, "We're  gonna do an experiment. Those Coke bottles over there (she had
a six-pack of empty Coke bottles that she was saving to send out) -- now you
haven't touched them in a couple of days, right?"
     "That's right."
     I took the six-pack over to her without touching the bottles, and said,
"OK. Now I'll go out, and  you take out one of  the  bottles, handle  it for
about  two minutes, and then put it back. Then I'll come in, and try to tell
which bottle it was."
     So I went out, and she took out one of the  bottles and  handled it for
quite  a while  -- lots of time, because I'm no bloodhound! According to the
article, they could tell if you just touched it.
     Then I came back, and it  was absolutely obvious! I didn't even have to
smell the damn thing, because, of course, the temperature was different. And
it was also obvious from the smell. As soon as you put it up near your face,
you  could smell it was  dampish and warmer. So  that experiment didn't work
because it was too obvious.
     Then I looked  at  the bookshelf  and said,  "Those  books you  haven't
looked at for a while, right?  This time,  when I go out, take one book  off
the shelf, and just open it -- that's all -- and close it again; then put it
back."
     So I went  out again, she took a book, opened it and closed it, and put
it back. I  came in -- and nothing  to  it! It was easy. You just  smell the
books. It's  hard to explain, because we're not  used to saying things about
it. You put  each book up  to your nose and  sniff a  few times, and you can
tell.  It's very different. A book that's been  standing there a while has a
dry, uninteresting kind of smell. But when a hand has touched it,  there's a
dampness and a smell that's very distinct.
     We did  a few more experiments, and I discovered that while bloodhounds
are indeed quite capable, humans are not as  incapable as  they  think  they
are: it's just that they carry their nose so high off the ground!
     (I've noticed that my dog can correctly tell which way I've gone in the
house, especially if I'm barefoot, by smelling my  footprints. So I tried to
do that: I crawled around the rug on my hands and knees, sniffing, to see if
I could tell the difference between where I walked and where I didn't, and I
found it impossible. So the dog is much better than I am.)
     Many years later, when I  was first at Caltech, there  was a  party  at
Professor Bacher's  house, and  there were a  lot of people  from Caltech. I
don't know  how it came up, but I was telling them this story about smelling
the  bottles  and  the books. They didn't believe a word, naturally, because
they always thought I was a faker. I had to demonstrate it.
     We  carefully took  eight or nine books off  the shelf without touching
them directly with our hands, and  then I  went out.  Three different people
touched three different books: they picked one up, opened it, closed it, and
put it back.
     Then I came back, and  smelled everybody's hands,  and smelled  all the
books -- I don't  remember  which I  did first -- and found all three  books
correctly; I got one person wrong.
     They still didn't believe me; they  thought it was  some sort  of magic
trick. They  kept trying to figure out how I did it. There's a famous  trick
of  this kind, where  you have  a confederate in  the  group  who gives  you
signals as  to  what  it  is, and they  were  trying to  figure out who  the
confederate was. Since then I've often thought that it would be  a good card
trick to take a  deck of cards and tell  someone to  pick a card and put  it
back, while you're in the other  room. You  say, "Now  I'm going to tell you
which card it is, because I'm  a bloodhound: I'm  going  to smell all  these
cards and tell you  which card you picked." Of  course,  with  that  kind of
patter, people wouldn't  believe for a  minute  that  that's  what  you were
actually doing!
     People's hands  smell very different --  that's why  dogs can  identify
people; you have to try  it!  All hands have  a  sort of  moist smell, and a
person who smokes has a very  different smell on his hands from a person who
doesn't;  ladies often  have different  kinds  of  perfumes, and so  on.  If
somebody  happened to  have  some coins  in his  pocket and happened  to  be
handling them, you can smell that.


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Los Alamos from Below*

     When I say "Los Alamos from below," I mean  that. Although in  my field
at  the present  time I'm a slightly  famous man,  at  that  time I  was not
anybody  famous at all. I didn't even have a degree  when  I started to work
with  the Manhattan Project. Many of the other people who tell you about Los
Alamos  --  people in higher echelons -- worried about some big decisions. I
worried about no big decisions. I was always flittering about underneath.
     I was working  in my room  at Princeton one day when Bob Wilson came in
and  said that he  had been funded  to  do a job  that was  a secret, and he
wasn't supposed to tell anybody, but he was going to tell me because he knew
that as  soon as I knew what  he was  going  to do, I'd see that I had to go
along with  it.  So he  told  me about the  problem of separating  different
isotopes  of uranium  to  ultimately  make a  bomb.  He  had a  process  for
separating  the  isotopes  of uranium (different  from  the  one  which  was
ultimately used) that he wanted to try to develop. He told me  about it, and
he said, "There's a meeting..."
     I said I didn't want to do it.
     He  said, "All  right, there's a meeting at three o'clock. I'll see you
there."
     I said, "It's all  right that  you  told me the secret because I'm  not
going to tell anybody, but I'm not going to do it."
     So I went back to work on my thesis -- for  about three minutes. Then I
began to pace the  floor and think about  this thing. The Germans had Hitler
and the possibility  of  developing  an  atomic  bomb was obvious,  and  the
possibility that  they would develop  it before we  did was very  much  of a
fright. So I decided to go to the meeting at three o'clock.
     By four  o'clock  I  already had  a desk in  a  room and  was trying to
calculate whether this particular method was limited by the total amount  of
current that you get in an ion beam, and so on. I won't go into the details.
But I had a desk, and I had paper, and I was  working as hard as I could and
as fast  as I could, so  the fellas who were building the apparatus could do
the experiment right there.
     It was like those moving pictures where you see a piece of equipment go
bruuuuup,  bruuuuup, bruuuuup. Every time I'd look up, the thing was getting
bigger. What was  happening, of course, was that all the boys had decided to
work on this  and  to stop  their research in  science. All  science stopped
during the war except the little bit that was done  at Los Alamos. And  that
was not much science; it was mostly engineering.
     All  the  equipment  from different  research projects  was  being  put
together  to make  the  new  apparatus to do the  experiment  -- to  try  to
separate the isotopes of uranium. I stopped my own work for the same reason,
though I did  take a six-week vacation after a while and finished writing my
thesis. And I did  get my degree just before  I got  to  Los Alamos -- so  I
wasn't quite as far down the scale as I led you to believe.
     One of  the  first  interesting  experiences I had  in  this project at
Princeton was meeting great men. I had never met very many great men before.
But there was an evaluation committee that  had to try to help us along, and
help us ultimately  decide  which way we were going to separate the uranium.
This committee had men like Compton and Tolman  and Smyth and Urey and  Rabi
and Oppenheimer on it. I would sit in because I understood the theory of how
our  process of separating isotopes worked, and so they'd ask  me  questions
and talk about it. In  these discussions one man would  make  a  point. Then
Compton, for example, would explain a  different point of view. He would say
it  should  be this way, and he was perfectly  right. Another guy would say,
well, maybe, but  there's this other possibility we have to consider against
it.
     So  everybody is  disagreeing, all around the table. I am surprised and
disturbed  that Compton doesn't repeat and emphasize his point.  Finally, at
the  end,  Tolman,  who's  the chairman, would say, "Well,  having heard all
these  arguments, I guess it's true that  Compton's argument is  the best of
all, and now we have to go ahead."
     It was such a shock to me to see that a committee of  men could present
a whole lot  of ideas, each one thinking  of a  new facet, while remembering
what the other fella said,  so that, at the end, the decision  is made as to
which idea was  the best --  summing  it all up -- without  having to say it
three times. These were very great men indeed.
     It was ultimately decided that this project was  not to be the one they
were going to use to  separate uranium. We were told then that we were going
to stop, because in  Los  Alamos, New  Mexico,  they  would be  starting the
project that would actually make the bomb. We would all go out there to make
it. There  would be experiments that we  would have  to do, and  theoretical
work to do. I was in the theoretical work. All the rest of the  fellas  were
in experimental work.
     The  question was -- What to do  now? Los Alamos wasn't ready  yet. Bob
Wilson tried to make use of this time by, among  other things, sending me to
Chicago  to find out all that  we could  find out about  the  bomb  and  the
problems. Then,  in our laboratories, we  could  start  to  build equipment,
counters of various  kinds,  and so  on, that would be useful when we got to
Los Alamos. So no time was wasted.
     I was sent to Chicago with the instructions to  go to each group,  tell
them I was going to work with them, and have them tell me about a problem in
enough  detail that  I  could actually sit down and start to  work on it. As
soon as I got that  far, I was  to go  to another  guy  and  ask for another
problem. That way I would understand the details of everything.
     It was a very good idea,  but my conscience  bothered me  a little  bit
because they would all work so hard to explain things to me, and I'd go away
without  helping them.  But  I  was  very  lucky. When one  of the  guys was
explaining a problem, I said, "Why don't  you do it by differentiating under
the  integral  sign?" In half an hour he  had  it solved,  and  they'd  been
working on it for three months. So, I did something, using my "different box
of tools." Then I  came back from Chicago, and I described  the situation --
how much  energy was  released,  what the bomb was going  to be like, and so
forth.
     I  remember  a  friend  of  mine  who  worked  with me,  Paul  Olum,  a
mathematician, came up to me afterwards  and said,  "When they make a moving
picture about  this, they'll have the guy  coming  back from Chicago to make
his report to the Princeton  men about the bomb. He'll be wearing a suit and
carrying a briefcase  and so on -- and here you're in dirty shirtsleeves and
just telling us  all about it,  in spite of  its  being  such a serious  and
dramatic thing."
     There still seemed to be a delay, and Wilson went to Los Alamos to find
out  what  was  holding things up.  When  he  got there,  he found  that the
construction company was working very hard and had finished the theater, and
a  few  other  buildings  that  they  understood,  but  they  hadn't  gotten
instructions clear  on how to build a laboratory -- how many pipes for  gas,
how much  for water.  So  Wilson  simply stood around and decided, then  and
there,  how  much water, how much gas, and so  on,  and  told them  to start
building the laboratories.
     When he came back  to  us, we were all ready to go and  we were getting
impatient. So they all  got together  and  decided we'd go out there anyway,
even though it wasn't ready.
     We were recruited, by the way, by Oppenheimer and other  people, and he
was very patient.  He  paid attention  to everybody's problems.  He  worried
about my wife, who had TB, and whether there would be a  hospital out there,
and everything. It was the first time I met him in such a  personal way;  he
was a wonderful man.
     We were  told to  be  very careful -- not to  buy our  train ticket  in
Princeton, for example, because Princeton was  a very small station,  and if
everybody bought  train  tickets to Albuquerque, New  Mexico,  in Princeton,
there would  be  some suspicions  that something  was  up. And so  everybody
bought  their  tickets somewhere else,  except  me,  because  I  figured  if
everybody bought their tickets somewhere else...
     So when  I went  to the  train  station  and said, "I  want  to  go  to
Albuquerque, New Mexico," the man says, "Oh, so all this stuff is  for you!"
We had been  shipping  out crates full of  counters  for weeks and expecting
that they didn't notice the address was Albuquerque. So at least I explained
why  it  was  that  we were shipping all  those crates; I  was going  out to
Albuquerque.
     Well, when we arrived, the houses and dormitories  and things like that
were not  ready. In fact, even the laboratories weren't quite ready. We were
pushing  them by  coming down  ahead of time. So  they  just  went crazy and
rented ranch houses  all around  the neighborhood. We  stayed at first in  a
ranch house and would drive in in the morning. The first morning I drove  in
was tremendously impressive. The beauty of the scenery, for  a  person  from
the East who didn't travel much, was sensational. There are the great cliffs
that you've probably seen in pictures. You'd come up from below  and be very
surprised to  see this high  mesa. The most impressive thing to me was that,
as I was going up, I said that maybe there had been Indians living here, and
the guy who was driving stopped the  car and walked  around  the  corner and
pointed out some Indian caves that you could inspect. It was very exciting.
     When I got to the site the first time, I saw there was a technical area
that  was  supposed to  have a fence  around it ultimately, but it was still
open. Then  there  was supposed to  be a town, and  then a big fence further
out, around the town. But they were still building, and my friend Paul Olum,
who was my assistant,  was standing at  the gate with  a clipboard, checking
the trucks coming in and out and telling them which way to go to deliver the
materials in different places.
     When I went into  the laboratory,  I would meet men I had  heard of  by
seeing their papers in the  Physical Review and so on.  I had never met them
before. "This  is John Williams," they'd say. Then  a guy  stands up  from a
desk that is covered  with blueprints,  his sleeves  all rolled up, and he's
calling  out  the windows, ordering  trucks and  things  going in  different
directions   with  building  material.  In  other  words,  the  experimental
physicists had nothing to do until their buildings and apparatus were ready,
so they just built the buildings -- or assisted in building the buildings.
     The theoretical  physicists,  on  the other  hand, could  start working
right away, so it was decided that they wouldn't  live in  the ranch houses,
but would live up at the site. We started working immediately. There were no
blackboards except for  one on wheels, and we'd  roll  it around and  Robert
Serber would explain to us all the things that they'd thought of in Berkeley
about  the atomic  bomb, and nuclear physics, and all these things. I didn't
know very much about it; I had been doing other kinds of things. So I had to
do an awful lot of work.
     Every day I would study and read, study and read. It was a  very hectic
time. But I  had some luck. All the big shots except for Hans Bethe happened
to  be away at the time, and what Bethe  needed was someone to  talk  to, to
push his ideas against. Well, he comes in to this little squirt in an office
and starts to argue,  explaining his  idea. I say, "No,  no,  you're  crazy.
It'll go like this." And he says, "Just a moment," and explains how he's not
crazy, I'm crazy. And we keep on going like this. You see, when I hear about
physics, I just think about physics, and I don't know who I'm talking to, so
I  say dopey things like "no, no, you're  wrong," or "you're crazy."  But it
turned out  that's exactly what  he needed.  I  got a notch up on account of
that, and I ended up as a group leader under Bethe with four guys under me.
     Well, when I was first there, as I said, the dormitories weren't ready.
But the theoretical  physicists had to stay up there anyway. The first place
they put us was in an old school building  -- a  boys' school that had  been
there previously. I  lived  in  a thing called the Mechanics' Lodge. We were
all  jammed in there in bunk beds, and it wasn't organized very well because
Bob Christy and his wife had to go  to the bathroom through our  bedroom. So
that was very uncomfortable.
     At last the dormitory was built. I went  down to  the place where rooms
were assigned, and  they  said, you can pick your room now. You know what  I
did? I looked to  see where  the girls' dormitory was,  and  then I picked a
room that looked right  across  -- though later I discovered a big tree  was
growing right in front of the window of that room.
     They told  me there would be two people in a room,  but that would only
be  temporary.  Every two rooms would share  a bathroom,  and there would be
double-decker bunks in each room. But I didn't want two people in the room.
     The night I got there, nobody else was there, and I  decided to  try to
keep my  room to myself. My  wife was sick with TB in Albuquerque, but I had
some  boxes of stuff of hers. So I  took  out a little nightgown, opened the
top bed, and threw the nightgown carelessly on it. I took out some slippers,
and I threw some  powder on the floor in the  bathroom. I  just made it look
like somebody else was there. So, what happened? Well, it's supposed to be a
men's dormitory, see? So I came home that night, and  my pajamas are  folded
nicely, and put under  the pillow at the  bottom, and my slippers put nicely
at the bottom of the bed. The lady's  nightgown  is nicely folded under  the
pillow, the  bed is  all fixed up  and  made, and  the slippers are put down
nicely.  The powder  is cleaned from the bathroom and nobody is  sleeping in
the upper bed.
     Next night, the same thing. When I  wake up, I rumple up the top bed, I
throw the nightgown on it  sloppily  and scatter the powder in  the bathroom
and so  on. I went on like this for  four nights until everybody was settled
and  there was  no more  danger  that they would put a second person in  the
room.  Each night,  everything was set out very neatly, even though it was a
men's dormitory.
     I  didn't know  it  then, but this  little  ruse  got  me  involved  in
politics.  There  were  all  kinds  of factions  there,  of  course  --  the
housewives' faction, the mechanics' faction, the technical peoples' faction,
and so on. Well, the bachelors and bachelor girls who lived in the dormitory
felt  they  had to  have  a  faction  too,  because  a  new  rule  had  been
promulgated:  No  Women  in  the  Men's   Dorm.  Well,  this  is  absolutely
ridiculous! After all, we are  grown people! What kind of nonsense  is this?
We had to have political action. So we debated this stuff, and I was elected
to represent the dormitory people in the town council.
     After I'd been in it for about a year and a half, I was talking to Hans
Bethe  about something. He was on the  big  governing council all this time,
and  I  told him  about  this trick with my  wife's  nightgown  and  bedroom
slippers. He started to laugh. "So that's how you got on  the town council,"
he said.
     It turned  out that what happened was  this.  The woman who cleans  the
rooms in  the dormitory opens this  door,  and  all  of  a  sudden  there is
trouble: somebody is sleeping with one of the guys! She reports to the chief
charwoman,  the chief charwoman reports to  the  lieutenant, the  lieutenant
reports to the major. It  goes  all the way  up  through the generals to the
governing board.
     What are they going  to do?  They're  going to  think about it,  that's
what! But,  in the meantime, what instructions go down through the captains,
down through the majors, through the lieutenants,  through the chars' chief,
through the charwoman? "Just put things back the way they are, clean 'em up,
and see what happens." Next day, same report. For four days, they worried up
there about  what they were going to do. Finally they promulgated a rule: No
Women in the  Men's  Dormitory! And that caused such a stink down below that
they had to elect somebody to represent the...

     I would like  to  tell you something  about the censorship that we  had
there. They decided to do  something utterly  illegal and censor the mail of
people inside the United States -- which they have no right to do. So it had
to be  set up very delicately  as a  voluntary thing. We would all volunteer
not to seal the envelopes of the letters we  sent out, and  it  would be all
right  for  them  to  open letters  coming in  to us;  that was  voluntarily
accepted by us. We would leave our letters open; and they would seal them if
they were  OK.  If they weren't  OK  in their opinion,  they would send  the
letter back to us with a note that there was a violation of  such and such a
paragraph of our "understanding."
     So, very delicately  amongst all these liberal-minded scientific  guys,
we  finally  got the censorship set up, with many rules. We were allowed  to
comment on the character of  the administration if we wanted to, so we could
write our senator and tell him we didn't  like the way things  were run, and
things  like  that. They said  they  would  notify  us  if  there  were  any
difficulties.
     So  it  was all  set up, and here  comes the  first day for censorship:
Telephone! Briiing!
     Me: "What?"
     "Please come down."
     I come down.
     "What's this?"
     "It's a letter from my father."
     "Well, what is it?"
     There's lined paper, and  there's these lines  going  out with  dots --
four dots  under,  one dot above, two dots under, one  dot  above, dot under
dot...
     "What's that?"
     I said, "It's a code."
     They said, "Yeah, it's a code, but what does it say?"
     I said, "I don't know what it says."
     They said, "Well, what's the key to the code? How do you decipher it?"
     I said, "Well, I don't know."
     Then they said, "What's this?"
     I said, "It's a letter from my wife -- it says TJXYWZ TW1X3."
     "What's that?"
     I said, "Another code."
     "What's the key to it?"
     "I don't know."
     They said, "You're receiving codes, and you don't know the key?"
     I said, "Precisely. I have a game.  I challenge them to  send me a code
that I can't decipher, see? So they're making up codes at the other end, and
they're sending them in, and they're not going to tell me what the key is."
     Now one of the rules  of the censorship  was that they  aren't going to
disturb  anything that you would ordinarily send in  the mail. So they said,
"Well, you're going to have to tell  them please to send the key in with the
code."
     I said, "I don't want to see the key!"
     They said, "Well, all right, we'll take the key out."
     So we had that arrangement. OK? All right. Next day I get a letter from
my wife  that  says,  "It's  very difficult writing because I feel that  the
--------
splotch made with ink eradicator.
     So I went down to the bureau, and I said, "You're not supposed to touch
the incoming mail if you don't like it. You  can  look at it, but you're not
supposed to take anything out."
     They said, "Don't be  ridiculous. Do  you think  that's the way censors
work -- with ink eradicator? They cut things out with scissors."
     I said OK. So I wrote a letter  back to  my wife and said, "Did you use
ink  eradicator  in  your  letter?" She  writes back, "No, I didn't  use ink
eradicator in my letter, it must have  been the _____" -- and there's a hole
cut out of the paper.
     So  I went back to  the  major who was supposed to be  in charge of all
this  and  complained. You know, this took a  little time, but  I felt I was
sort of the  representative to get the  thing straightened  out.  The  major
tried to  explain to me that these people who  were  the  censors  had  been
taught how to do  it, but they didn't understand this new way that we had to
be so delicate about.
     So, anyway, he said,  "What's the matter, don't you  think I  have good
will?"
     I  said, "Yes, you have  perfectly good will but I don't think you have
power." Because, you see, he had already been on the job three or four days.
     He said, "We'll see about that!" He grabs the telephone, and everything
is straightened out. No more is the letter cut.
     However,  there were a number of other difficulties.  For example,  one
day I got a letter from my wife and a note from the censor that said, "There
was a code enclosed without the key, and so we removed it."
     So when I went to see my wife in Albuquerque that day, she said, "Well,
where's all the stuff?"
     I said, "What stuff?"
     She said, "Litharge, glycerine, hot dogs, laundry."
     I said, "Wait a minute -- that was a list?"
     She said, "Yes."
     "That  was a  code,"  I  said.  "They  thought it was a  code-litharge,
glycerine, etc."  (She wanted litharge and glycerine to make a cement to fix
an onyx box.)
     All  this went  on in  the first  few weeks  before  we  got everything
straightened  out. Anyway, one day  I'm  piddling around with  the computing
machine, and I notice something very peculiar. If you take 1  divided by 243
you get .004115226337... It's quite cute: It goes  a  little cockeyed  after
559 when  you're carrying but it soon  straightens itself  out  and  repeats
itself nicely. I thought it was kind of amusing.
     Well,  I put that in the mail, and it comes back  to me.  It doesn't go
through,  and  there's  a little note: "Look at  Paragraph  17B." I  look at
Paragraph 17B. It says, "Letters are to be written only in English, Russian,
Spanish,  Portuguese, Latin, German, and  so forth.  Permission  to use  any
other language must be obtained in writing." And then it said, "No codes."
     So I wrote back to the censor a little note included in my letter which
said  that I  feel that  of course this cannot be  a  code, because  if  you
actually do divide 1 by  243,  you do, in fact,  get all that, and therefore
there's no more information in the number .004115226337...  than there is in
the number 243 -- which is  hardly any information  at all. And  so forth. I
therefore  asked for permission to use Arabic  numerals  in my letters. So I
got that through all right.
     There was  always  some kind of difficulty  with the letters going back
and  forth.  For example, my  wife kept  mentioning  the  fact that she felt
uncomfortable writing with the feeling that the censor is  looking over  her
shoulder. Now, as a rule,  we  aren't  supposed to  mention  censorship.  We
aren't, but how can they  tell her? So they keep  sending me  a note:  "Your
wife mentioned  censorship."  Certainly,  my  wife mentioned  censorship. So
finally  they  sent me a note  that  said,  "Please inform your  wife not to
mention  censorship in her  letters."  So  I  start  my letter: "I have been
instructed to  inform you not to mention censorship in your letters." Phoom,
phoooom, it comes  right back! So I write, "I have been instructed to inform
my  wife  not to  mention  censorship. How in the heck am I going  to do it?
Furthermore, why do I have to instruct her not  to  mention censorship?  You
keeping something from me?"
     It is very interesting that  the  censor himself has to tell me to tell
my wife not to tell me that she's... But they had an answer. They said, yes,
that  they  are  worried  about  mail  being  intercepted on  the  way  from
Albuquerque, and that someone might find  out that there  was  censorship if
they looked in the mail, and would she please act much more normal.
     So I  went down the next time to Albuquerque, and I talked to her and I
said,  "Now, look, let's not mention  censorship."  But  we  had had so much
trouble that we at last worked out a code, something illegal. If I would put
a dot at the end  of my signature, it meant I had had trouble again, and she
would move on to the next of the moves that she had concocted. She would sit
there all  day long, because  she was ill,  and she would think of things to
do. The last thing  she did  was to send me an advertisement which she found
perfectly legitimately.  It  said, "Send your boyfriend a letter on a jigsaw
puzzle. We sell  you the  blank,  you  write the letter  on it, take  it all
apart, put it in a  little sack, and  mail it." I received  that  one with a
note saying, "We do not have  time to play games. Please instruct your  wife
to confine herself to ordinary letters."
     Well, we were ready  with the one more dot, but  they straightened  out
just in time  and we didn't  have to use it. The thing we had  ready for the
next one was  that the letter  would start, "I hope you  remembered  to open
this  letter carefully because I have included the Pepto-Bismol  powder  for
your stomach  as we arranged." It would be a  letter full of powder. In  the
office we expected they  would open it quickly, the powder would go all over
the floor, and  they  would  get  all  upset because you are not supposed to
upset anything.  They'd  have to  gather up all this Pepto-Bismol...  But we
didn't have to use that one.
     As a result of all  these experiences  with the  censor, I knew exactly
what could  get through and what  could not get through. Nobody else knew as
well as I. And so I made a little money out of all of this by making bets.
     One day I discovered that the workmen who  lived further out and wanted
to come in were too lazy to go around through the gate, and  so they had cut
themselves a hole  in the fence. So  I went out  the gate, went  over to the
hole and came in, went out again, and  so on, until the sergeant at the gate
began to wonder  what was  happening.  How come this guy is always going out
and never coming in? And,  of  course, his natural reaction was to call  the
lieutenant and try to put me in jail for doing this. I explained  that there
was a hole.
     You see, I was always trying to straighten people out. And so I made  a
bet with somebody that I could tell about the hole in the fence in a letter,
and mail it  out. And sure enough,  I did. And  the way I did it was I said,
You  should see  the  way they  administer this place (that's  what  we were
allowed to  say). There's a  hole in the fence  seventy-one  feet away  from
such-and-such  a place, that's  this size and  that size, that you can  walk
through.
     Now, what can they do? They can't say to me that there is no such hole.
I mean,  what  are they going to do? It's  their own  hard luck that there's
such a hole. They should fix the hole. So I got that one through.
     I also got through a letter  that  told  about how  one of the boys who
worked in one of my groups,  John Kemeny, had been wakened up  in the middle
of the night and grilled  with lights in front  of him by some idiots in the
army  there because  they found  out  something  about his  father,  who was
supposed to be a communist or something. Kemeny is a famous man now.
     There were  other things.  Like the hole in  the  fence,  I  was always
trying to  point these things out in  a non-direct  manner.  And  one of the
things I wanted to point out was this  -- that  at the very beginning we had
terribly  important secrets;  we'd worked out lots of stuff about bombs  and
uranium and  how it  worked, and so on; and all this  stuff was in documents
that  were  in  wooden filing cabinets  that had  little,  ordinary,  common
padlocks on them.  Of course,  there were  various things  made by the shop,
like a rod  that  would  go  down and then a padlock to  hold it, but it was
always just a padlock. Furthermore, you could get the stuff out without even
opening the  padlock. You  just tilt the  cabinet over backwards. The bottom
drawer has  a little  rod that's supposed  to  hold the papers together, and
there's a long wide hole in the wood underneath. You can pull the papers out
from below.
     So I used to pick the locks all the time and point out that it was very
easy to do. And every time we had a meeting of everybody  together, I  would
get up and say that we have important secrets and  we shouldn't keep them in
such things; we need better locks. One day Teller got up at the meeting, and
he said to me, "I don't keep my most important secrets in my filing cabinet;
I keep them in my desk drawer. Isn't that better?"
     I said, "I don't know. I haven't seen your desk drawer."
     He was  sitting near the  front of the meeting, and I'm sitting further
back. So  the meeting continues, and I sneak out and go down to see his desk
drawer.
     I don't  even have to pick the lock  on the  desk drawer.  It turns out
that if you  put your  hand  in  the back, underneath, you can  pull out the
paper  like  those toilet paper  dispensers.  You pull  out  one,  it  pulls
another, it pulls another... I emptied the whole damn drawer, put everything
away to one side, and went back upstairs.
     The meeting was just ending, and everybody was coming out, and I joined
the crew and ran to catch up with Teller, and I said, "Oh,  by the  way, let
me see your desk drawer."
     "Certainly," he said, and he showed me the desk.
     I looked at it and said, "That looks pretty  good to me. Let's see what
you have in there."
     "I'll be very glad to show it to  you," he said, putting in the key and
opening the drawer. "If," he said, "you hadn't already seen it yourself."
     The trouble with  playing a trick on a highly intelligent man like  Mr.
Teller is that the time it takes him  to figure out  from the moment that he
sees there  is something wrong till he understands exactly what  happened is
too damn small to give you any pleasure!

     Some  of  the  special  problems  I  had  at  Los  Alamos  were  rather
interesting. One thing had to do with the safety of  the plant at Oak Ridge,
Tennessee. Los Alamos was going to make the bomb, but at Oak Ridge they were
trying to  separate the isotopes of  uranium -- uranium 238 and uranium 235,
the  explosive one. They  were just beginning  to  get infinitesimal amounts
from an experimental thing of 235, and at the same time they were practicing
the chemistry.  There was going to  be  a big plant, they were going to have
vats of the stuff, and then they were going  to take the  purified stuff and
repurify and  get it ready  for the next  stage. (You have to  purify it  in
several stages.) So they were practicing on the one hand, and they were just
getting  a  little  bit  of  U235  from  one  of  the  pieces  of  apparatus
experimentally on the other hand. And they were trying to learn how to assay
it, to determine  how much uranium 235 there  is in it. Though we would send
them instructions, they never got it right.
     So finally Emil Segre said that the  only possible way  to get it right
was for him to go down there and see what they were doing.  The  army people
said, "No, it is our policy to keep all the information of Los Alamos at one
place."
     The people in  Oak  Ridge didn't know  anything about what it was to be
used for; they just  knew  what  they were trying  to  do. I mean the higher
people knew they were separating uranium, but they didn't  know how powerful
the bomb was, or exactly  how it  worked or anything. The people  underneath
didn't know at all what they were doing. And the army wanted to keep it that
way. There  was  no information  going  back  and forth.  But Segre insisted
they'd never get the assays right, and the whole thing would go up in smoke.
So he finally  went down to see what they were doing, and as he  was walking
through he saw them wheeling a tank carboy of water, green water -- which is
uranium nitrate solution.
     He said,  "Uh, you're going  to  handle it like that when it's purified
too? Is that what you're going to do?"
     They said, "Sure -- why not?"
     "Won't it explode?" he said.
     Huh! Explode?
     Then the army said, "You see! We shouldn't have let any information get
to them! Now they are all upset."
     It turned  out that the army had realized how much stuff we  needed  to
make a bomb -- twenty kilograms or whatever it was -- and they realized that
this much material, purified, would never  be in the plant, so there was  no
danger. But they  did  not  know  that  the  neutrons  were enormously  more
effective when they are slowed down in water. In water it takes less than  a
tenth -- no,  a  hundredth -- as much material to make a reaction that makes
radioactivity. It kills people around and so  on. It was very dangerous, and
they had not paid any attention to the safety at all.
     So a telegram goes from  Oppenheimer  to Segre:  "Go through the entire
plant.  Notice where  all the concentrations  are supposed  to be,  with the
process  as they  designed  it. We  will  calculate in the meantime how much
material can come together before there's an explosion."
     Two  groups started  working  on  it. Christy's  group worked on  water
solutions  and my group worked  on dry powder  in boxes. We calculated about
how much material they could accumulate safely.  And Christy was going to go
down and tell them  all at  Oak Ridge what the situation  was, because  this
whole thing is  broken down and we  have to go down and  tell them now. So I
happily gave all my numbers to Christy and said, you have  all the stuff, so
go. Christy got pneumonia; I had to go.
     I had never traveled on  an airplane before. They  strapped the secrets
in  a little thing  on my back! The  airplane in  those days was like a bus,
except the  stations were  further apart. You stopped  off every  once  in a
while to wait.
     There was  a guy  standing  there  next  to me swinging a chain, saying
something like, "It must be terribly difficult to fly without a priority  on
airplanes these days."
     I couldn't resist. I said, "Well, I don't know. I have a priority."
     A little bit later he tried  again.  "There  are  some generals coming.
They are going to put off some of us number threes."
     "It's all right," I said. "I'm a number two."
     He probably wrote to  his congressman  --  if he  wasn't a  congressman
himself -- saying, "What are they  doing sending  these little  kids  around
with number two priorities in the middle of the war?"
     At any  rate,  I arrived at Oak Ridge.  The  first thing I did was have
them take me to the plant, and I said nothing. I just  looked at everything.
I  found out that the situation was even  worse than Segre reported, because
he  noticed certain boxes in big lots in a room, but he didn't  notice a lot
of  boxes in another room on the  other  side of the same wall -- and things
like that. Now, if you have too much stuff together, it goes up, you see.
     So I went through the entire plant. I  have a very bad memory, but when
I work intensively I  have a good short-term memory, and so I could remember
all kinds of crazy things like building 90-207, vat number so-and-so, and so
forth.
     I went to  my  room  that  night,  and went  through  the  whole thing,
explained where all the dangers were,  and what you would  have to do to fix
this. It's rather easy. You  put cadmium in solutions to absorb the neutrons
in  the  water, and  you separate  the boxes  so  they are  not  too  dense,
according to certain rules.
     The next day there was going  to be a big meeting. I forgot to say that
before I left Los Alamos Oppenheimer said to me, "Now,  the following people
are technically  able  down  there  at  Oak  Ridge:  Mr.  Julian  Webb,  Mr.
So-and-so, and  so on. I want you to make sure that  these people are at the
meeting, that you tell them  how the thing can  be made safe,  so  that they
really understand."
     I said, "What if they're not at the meeting? What am I supposed to do?"
     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,  down-up-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  be 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 bunch 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!"
     And so the rule was: All other problems  out. Only one problem and just
concentrate on this one. So they started to work.
     My wife,  Arlene,  was  ill  with  tuberculosis  -- very ill indeed. It
looked as if  something  might happen at any minute,  so I arranged ahead of
time with a  friend  of mine  in  the  dormitory  to borrow his  car  in  an
emergency so I  could get  to Albuquerque quickly. His name was Klaus Fuchs.
He was the  spy, and he  used his automobile to take the atomic secrets away
from Los Alamos down to Santa Fe. But nobody knew that.
     The emergency arrived. I borrowed Fuchs's car and picked up a couple of
hitchhikers,  in case  something  happened  with  the  car  on  the  way  to
Albuquerque.  Sure enough, just  as  we were driving into Santa Fe, we got a
flat tire.  The  two guys  helped me  change  the tire, and just as  we were
leaving Santa Fe, another tire went  flat. We pushed  the car  into a nearby
gas station.
     The gas station guy was repairing somebody else's car, and it was going
to take  a  while  before  he  could  help us. I  didn't even  think  to say
anything, but  the two hitchhikers went over to the gas station man and told
him the situation. Soon we had a new tire (but no  spare -- tires were  hard
to get during the war).
     About thirty miles  outside Albuquerque a third  tire  went flat,  so I
left the car on the road and we hitchhiked the  rest  of the way. I phoned a
garage  to go out and get  the car while  I went to the  hospital  to see my
wife.
     Arlene died a few  hours after I got there. A nurse came in to fill out
the death certificate, and went out again. I spent  a little  more time with
my wife. Then I looked at the clock I had given her seven years before, when
she had first become sick with tuberculosis. It was something which in those
days was very  nice:  a digital clock whose numbers would change  by turning
around mechanically. The  clock was very delicate and often stopped for  one
reason or another -- I had  to repair it from time to time -- but I kept  it
going  for  all those years. Now, it had stopped once more  --  at 9:22, the
time on the death certificate!
     I remembered the time I was in my fraternity house at MIT when the idea
came into my head completely out  of the blue that  my grandmother was dead.
Right after that there was a telephone call, just like that. It was for Pete
Bernays --  my  grandmother  wasn't  dead.  So  I remembered  that,  in case
somebody told  me a  story that  ended  the other way.  I figured that  such
things can  sometimes happen by luck --  after all, my grandmother was  very
old  --  although  people  might  think  they  happened  by  some   sort  of
supernatural phenomenon.
     Arlene had  kept this clock by her bedside  all the time she  was sick,
and now it stopped the moment she died. I  can  understand  how a person who
half  believes  in  the possibility  of  such things,  and who  hasn't got a
doubting  mind  --  especially  in  a  circumstance  like  that  --  doesn't
immediately try to figure  out  what happened, but  instead explains that no
one touched the clock, and there was no possibility of explanation by normal
phenomena. The clock simply stopped. It would  become a dramatic example  of
these fantastic phenomena.
     I saw that the light in  the  room was low, and then I  remembered that
the nurse had picked up the clock  and turned it toward the light to see the
face better. That could easily have stopped it.
     I went for a walk  outside.  Maybe  I  was fooling  myself,  but  I was
surprised how I didn't feel what I thought people would expect to feel under
the  circumstances. I  wasn't delighted, but  I didn't feel terribly  upset,
perhaps  because I had known for seven years that  something  like this  was
going to happen.
     I didn't know how I  was going to face all my friends up at Los Alamos.
I didn't want people with long faces talking to me about it. When I got back
(yet another tire went flat on the way), they asked me what happened.
     "She's dead. And how's the program going?"
     They caught on right away that I didn't want to moon over it.
     (I had  obviously done something to myself psychologically: Reality was
so  important  --  I  had  to understand what  really  happened  to  Arlene,
physiologically -- that I didn't cry  until a number of months later, when I
was in  Oak Ridge. I was walking past a department store with dresses in the
window, and I thought Arlene would like  one of them.  That was too much for
me.)
     When I went back to work  on the  calculation program, I  found it in a
mess:  There were  white cards,  there  were blue cards,  there  were yellow
cards, and  I started to say,  "You're  not  supposed  to do  more  than one
problem -- only one problem!" They said, "Get out, get out, get out. Wait --
and we'll explain everything."
     So  I waited, and  what  happened was this.  As the cards went through,
sometimes the machine made a mistake, or they put a wrong number in. What we
used to  have to do when that  happened was to go back and do it over again.
But they noticed that a mistake made at some point in one cycle only affects
the nearby numbers, the next cycle affects the nearby numbers, and so on. It
works its  way through the  pack of cards. If  you have fifty  cards and you
make  a  mistake  at  card  number  thirty-nine,  it  affects  thirty-seven,
thirty-eight,  and  thirty-nine.  The  next,  card thirty-six, thirty-seven,
thirty-eight, thirty-nine, and  forty.  The  next time  it  spreads  like  a
disease.
     So they found an  error  back a  way,  and they got an idea. They would
only  compute a small deck of ten cards  around the error. And  because  ten
cards could be put through the machine faster than the deck of fifty  cards,
they would go rapidly through with this other deck while they continued with
the  fifty cards with  the  disease  spreading.  But  the  other  thing  was
computing faster, and they would seal it all up and correct it. Very clever.
     That was the  way  those  guys worked to get speed. There  was no other
way. If they had to stop to try to fix it, we'd have  lost time. We couldn't
have got it. That was what they were doing.
     Of  course, you know what happened while  they were  doing  that.  They
found an error in the blue deck. And so they had a yellow deck with a little
fewer cards; it was  going around  faster than the blue deck. Just when they
are going crazy --  because  after they get this straightened out, they have
to fix the white deck -- the boss comes walking in.
     "Leave us alone," they say.  I left them alone and everything came out.
We solved the problem in time and that's the way it was.

     I was an underling at the beginning. Later I became a group leader. And
I met some very great men. It is one of the great experiences  of my life to
have met all these wonderful physicists.
     There  was, of course, Enrico Fermi. He came down once from Chicago, to
consult a little bit, to help us if we had some  problems. We had a  meeting
with him, and I  had been  doing some calculations and  gotten some results.
The calculations  were so elaborate -- it was very difficult. Now, usually I
was the expert at this; I could always tell you what the answer was going to
look like,  or when I  got it  I could explain  why.  But this  thing was so
complicated I couldn't explain why it was like that.
     So I told Fermi I was doing this problem, and I started to describe the
results. He said, "Wait,  before you tell me the  result, let me think. It's
going to come out like this (he was right), and it's  going to come out like
this because of so and so. And there's a  perfectly  obvious explanation for
this --"
     He was doing what I was supposed to be  good at, ten times better. That
was quite a lesson to me.
     Then there was John von Neumann, the great mathematician. We used to go
for walks  on Sunday.  We'd walk  in  the canyons,  often with Bethe and Bob
Bacher. It was a  great pleasure. And von  Neumann  gave  me an  interesting
idea: that you don't have to be responsible for the world that you're in. So
I  have  developed a  very powerful  sense of  social irresponsibility as  a
result  of von Neumann's advice. It's  made me  a very happy man ever since.
But  it was  von  Neumann who  put  the  seed  in that  grew  into my active
irresponsibility!
     I also met Niels  Bohr. His name was  Nicholas Baker in those days, and
he came to Los Alamos  with Jim  Baker, his  son, whose name is really  Aage
Bohr. They came from Denmark, and they were very  famous  physicists, as you
know. Even to the big shot guys, Bohr was a great god.
     We were at a meeting once, the first time he came, and everybody wanted
to  see  the great Bohr. So there  were a  lot of people  there, and we were
discussing the  problems  of the  bomb. I was back in a corner somewhere. He
came and went, and all I could see of him was from between people's heads.
     In the morning of the day he's due to come next time, I get a telephone
call.
     "Hello -- Feynman?"
     "Yes."
     "This is Jim Baker." It's his son. "My father and I would like to speak
to you."
     "Me? I'm Feynman, I'm just a --"
     "That's right. Is eight o'clock OK?"
     So, at eight o'clock in  the morning, before anybody's awake, I go down
to the place. We  go into  an office in the technical area and he says,  "We
have been thinking how we could make the bomb more efficient and we think of
the following idea."
     I say, "No, it's not  going to work. It's not efficient...  Blah, blah,
blah."
     So he says, "How about so and so?"
     I said, "That sounds a  little  bit better, but it's got this damn fool
idea in it."
     This went on for about two  hours, going back and forth  over  lots  of
ideas,  back and forth, arguing. The great Niels kept lighting his pipe;  it
always  went  out.  And  he talked in a  way that  was  un-understandable --
mumble, mumble, hard to understand. His son I could understand better.
     "Well," he said finally, lighting his pipe, "I guess we can call in the
big shots  now." So then they called all the other guys and had a discussion
with them.
     Then the son told me  what happened.  The last time  he was there, Bohr
said  to his son, "Remember the name of that little fellow in the  back over
there? He's the only guy who's not afraid of me, and will say  when I've got
a crazy idea. So next time when we want to discuss ideas, we're not going to
be able to do  it with these guys who say everything is  yes, yes, Dr. Bohr.
Get that guy and we'll talk with him first."
     I was always dumb in that way. I never knew who I was talking to. I was
always worried about the physics. If the idea looked lousy, I said it looked
lousy. If it looked good, I said it looked good. Simple proposition.
     I've always  lived that way. It's nice, it's pleasant  -- if you can do
it. I'm lucky in my life that I can do this.
     After  we'd made the  calculations, the  next  thing that happened,  of
course, was the test. I was actually at home  on a  short  vacation  at that
time, after my  wife died,  and so I got a  message that said,  "The baby is
expected on such and such a day."
     I flew back, and I arrived just when the buses were leaving,  so I went
straight out to the site and we waited out there, twenty miles away.  We had
a radio, and they  were supposed to tell us when the  thing  was going to go
off and  so forth,  but the radio wouldn't work, so we never  knew  what was
happening. But just a few minutes before it was supposed to go off the radio
started to work, and they told  us there was twenty seconds or something  to
go, for people who were far away like we were. Others were closer, six miles
away.
     They gave out dark glasses  that you could watch it with. Dark glasses!
Twenty miles away, you couldn't see a damn  thing through dark glasses. So I
figured the  only thing  that could  really hurt your eyes (bright light can
never hurt your eyes) is ultraviolet light. I got behind a truck windshield,
because the ultraviolet  can't go through glass, so that would be  safe, and
so I could see the damn thing.
     Time comes, and  this  tremendous  flash out there is so  bright that I
duck,  and I  see this  purple splotch on the floor  of  the truck.  I said,
"That's not it. That's  an  after-image." So I look back up, and  I see this
white  light  changing  into yellow  and then  into orange.  Clouds form and
disappear again -- from the compression and expansion of the shock wave.
     Finally, a big ball of orange, the center that was so bright, becomes a
ball of orange that starts to rise and billow a little bit and get a  little
black  around the  edges,  and then you see  it's a big  ball of smoke  with
flashes on the inside, with the heat of the fire going outwards.
     All  this took about one  minute.  It was a series from bright to dark,
and  I had seen it. I am about the only guy who actually  looked at the damn
thing -- the first  Trinity test. Everybody  else had dark glasses, and  the
people at six miles couldn't see it because they were all told to lie on the
floor. I'm probably the only guy who saw it with the human eye.
     Finally, after about a minute and a half, there's suddenly a tremendous
noise -- BANG, and then a rumble, like thunder -- and  that's what convinced
me.  Nobody  had said  a word during  this  whole thing.  We were  all  just
watching  quietly.  But  this  sound  released   everybody  --  released  me
particularly because the  solidity of the sound at that distance meant  that
it had really worked.
     The man standing next to me said, "What's that?"
     I said, "That was the Bomb."
     The  man  was William  Laurence.  He  was  there  to  write an  article
describing the  whole situation. I had been the one who was supposed to have
taken him around. Then it was found that it was too  technical  for him, and
so later H. D. Smyth came and I showed him around. One thing we did, we went
into  a  room  and  there  on the  end of  a narrow  pedestal  was  a  small
silver-plated ball.  You could  put  your hand on  it. It was  warm.  It was
radioactive. It  was  plutonium. And  we  stood  at  the door  of this room,
talking about  it. This  was a  new element that was made  by man, that  had
never existed on the earth before, except  for a very short period  possibly
at the very  beginning. And here it was all isolated and radioactive and had
these properties. And we had made it. And so it was tremendously valuable.
     Meanwhile, you know how people do when they talk -- you  kind of jiggle
around and so forth. He was kicking the doorstop, you see, and I said, "Yes,
the doorstop  certainly is appropriate for  this  door." The doorstop was  a
ten-inch hemisphere of yellowish metal-gold, as a matter of fact.
     What had  happened was that  we needed to do an  experiment  to see how
many neutrons were reflected by different  materials, in order  to  save the
neutrons so we didn't use  so much  material. We had  tested  many different
materials.  We had tested platinum, we had tested zinc, we had tested brass,
we had tested gold. So,  in  making  the tests with  the gold,  we had these
pieces of gold  and somebody had the clever idea of using that great ball of
gold for a doorstop for the door of the room that contained the plutonium.
     After  the  thing  went  off,  there  was tremendous  excitement at Los
Alamos. Everybody had parties, we all ran around. I sat on the end of a jeep
and beat drums and  so  on.  But one man, I remember, Bob  Wilson, was  just
sitting there moping.
     I said, "What  are you moping about?" He said, "It's  a terrible  thing
that  we made." I said, "But you started it. You got us into  it." You  see,
what happened to me -- what happened to the rest  of us -- is we started for
a good  reason,  then you're  working very hard to  accomplish something and
it's a  pleasure, it's excitement. And you stop thinking, you know; you just
stop. Bob Wilson was  the only one  who was still thinking about it, at that
moment.
     I returned to civilization shortly after  that and went  to Cornell  to
teach, and my first impression was a very strange one. I can't understand it
any more, but I felt very strongly  then. I sat in a restaurant in New York,
for example, and I  looked out  at  the buildings and I began  to think, you
know,  about how  much the radius  of the  Hiroshima  bomb damage was and so
forth...  How far from here was  34th Street?...  All those  buildings,  all
smashed -- and so on. And I would go along and I would see people building a
bridge, or they'd be making a new road,  and I  thought, they're crazy, they
just don't  understand,  they  don't  understand. Why  are  they making  new
things? It's so useless.
     But, fortunately,  it's been useless for almost forty years now, hasn't
it? So  I've been wrong about  it  being useless making bridges and I'm glad
those other people had the sense to go ahead.


--------
Safecracker Meets Safecracker

     I  learned  to pick locks from a guy named Leo Lavatelli.  It turns out
that picking ordinary tumbler locks  -- like Yale  locks -- is easy. You try
to turn the lock by putting a screwdriver in the hole (you have to push from
the side in order to leave the hole open). It doesn't turn because there are
some pins  inside which have to be lifted to just the  right height (by  the
key). Because it is  not made  perfectly, the  lock is  held more by one pin
than the others. Now, if you push a little wire gadget -- maybe a paper clip
with a slight bump at the end -- and jiggle it  back and  forth  inside  the
lock, you'll eventually push that one pin that's doing the most  holding, up
to  the right height. The lock  gives, just a  little bit, so the first  pin
stays up -- it's caught on the edge. Now most of the load is held by another
pin,  and you repeat the same random process  for a few more minutes,  until
all the pins are pushed up.
     What  often  happens is  that  the  screwdriver will slip and  you hear
tic-tic-tic, and it makes you mad.  There are little springs  that  push the
pins  back down when a key is  removed, and you can hear them click when you
let  go of  the  screwdriver. (Sometimes you  intentionally let  go  of  the
screwdriver to  see  if you're getting  anywhere -- you might be pushing the
wrong way, for instance.) The process is  something  like  Sisyphus:  you're
always falling back downhill.
     It's a simple process, but  practice helps a lot. You learn how hard to
push on things -- hard enough so the pins will stay up, but not so hard that
they won't go up in the first place. What is not really appreciated  by most
people  is  that  they're  perpetually  locking  themselves  in  with  locks
everywhere, and it's not very hard to pick them.
     When we  started  to work  on the  atomic bomb  project  at Los Alamos,
everything was in such a hurry that it  wasn't really ready. All the secrets
of the project -- everything about the  atomic bomb  -- were kept in  filing
cabinets which, if they had locks at  all, were locked with  padlocks  which
had maybe only three pins: they were as easy as pie to open.
     To improve security the shop outfitted every filing cabinet with a long
rod that went down through  the handles of the drawers and that was fastened
by a padlock.
     Some guy said to me, "Look at this new thing the shop put on -- can you
open the cabinet now?"
     I looked at  the  back  of  the cabinet and saw that the drawers didn't
have  a solid bottom. There was a slot with a wire rod in each one that held
a slidable piece (which holds  the papers up inside the  drawer). I poked in
from the back, slid the piece back, and began pulling the papers out through
the slot. "Look!" I said. "I don't even have to pick the lock."
     Los  Alamos  was  a  very  cooperative   place,  and  we  felt  it  our
responsibility  to  point  out  things  that should  be improved.  I'd  keep
complaining that the stuff was unsafe, and although everybody thought it was
safe because there  were  steel rods  and padlocks,  it  didn't  mean a damn
thing.
     To  demonstrate  that  the  locks  meant  nothing,  whenever  I  wanted
somebody's report and they weren't around, I'd just go in their office, open
the filing cabinet, and take it  out. When I was  finished  I  would give it
back to the guy: "Thanks for your report."
     "Where'd you get it?"
     "Out of your filing cabinet."
     "But I locked it!"
     "I know you locked it. The locks are no good."
     Finally some  filing cabinets  came which had combination locks on them
made by the Mosler  Safe Company.  They had  three  drawers. Pulling the top
drawer out would release the other drawers by  a catch.  The top drawer  was
opened by turning a  combination wheel to  the left, right, and left for the
combination, and then right to  number ten,  which would  draw  back  a bolt
inside. The  whole filing  cabinet could  be locked  by  closing  the bottom
drawers first,  then the top drawer, and spinning the combination wheel away
from number ten, which pushed up the bolt.
     These new  filing cabinets  were an immediate  challenge,  naturally. I
love puzzles. One guy tries to make something to keep another guy out; there
must be a way to beat it!
     I had first to understand how the lock worked, so I took apart the  one
in my office. The  way it worked is this: There are three  discs on a single
shaft, one behind the other; each has a notch in a different place. The idea
is to line up the notches so that when you turn the wheel to ten, the little
friction drive will draw  the  bolt  down into  the slot  generated  by  the
notches of the three discs.
     Now, to turn the discs, there's a pin sticking out from the back of the
combination wheel, and a  pin sticking up  from the first disc  at the  same
radius. Within one turn of the combination wheel, you've picked up the first
disc.
     On the back of the first disc there's a pin at the same radius as a pin
on the front  of the second disc, so by the time you've spun the combination
wheel around twice, you've picked up the second disc as well.
     Keep turning the wheel, and  a pin on the back of the  second disc will
catch  a  pin on the front of the third disc,  which  you  now set into  the
proper position with the first number of the combination.
     Now you have to turn the combination  wheel the other way one full turn
to  catch  the  second disc from  the other  side, and then continue  to the
second number of the combination to set the second disc.
     Again you reverse direction and set the first disc to its proper place.
Now the notches  are lined up, and by turning the wheel to ten, you open the
cabinet.
     Well, I  struggled,  and I couldn't  get anywhere. I bought a couple of
Safecracker books,  but they were all the same. In the beginning of the book
there are some  stories of the fantastic  achievements  of the  safecracker,
such as  the woman caught  in a meat refrigerator who is  freezing to death,
but the safecracker,  hanging upside down, opens it in two minutes. Or there
are some precious furs or gold bullion under water, down in the sea, and the
safecracker dives down and opens the chest.
     In the second  part  of the book, they tell  you how to  crack a  safe.
There are all kinds of ninny-pinny, dopey  things, like "It might be  a good
idea to try a date for the combination, because  lots of people like to  use
dates." Or "Think of  the  psychology  of the owner of the safe, and what he
might use for the combination." And "The secretary is often worried that she
might forget the combination of the safe, so  she might write it down in one
of the following  places -- along the edge of her desk drawer, on a  list of
names and addresses..." and so on.
     They did  tell me something sensible  about how to open ordinary safes,
and it's easy to understand.  Ordinary safes have an extra handle, so if you
push  down on the handle while you're turning  the combination wheel, things
being  unequal  (as with locks), the force  of the handle trying to push the
bolt down  into the notches (which are not lined up) is held up more by  one
disc than another. When the notch on that disc comes under the bolt, there's
a tiny click that you can  hear with  a stethoscope, or a slight decrease in
friction that you  can  feel (you don't have to sandpaper  your fingertips),
and you know, "There's a number!"
     You don't know whether it's the first, second, or third number, but you
can get a pretty good idea of that by finding out how many times you have to
turn  the wheel the other way to hear the same click again. If it's a little
less  than once, it's the first disc; if it's a little less than twice, it's
the  second disc (you  have to  make a  correction for the thickness of  the
pins).
     This useful trick only works on ordinary  safes, which  have  the extra
handle, so I was stymied.
     I tried all  kinds  of subsidiary  tricks  with the cabinets,  such  as
finding out how to release the latches on the lower drawers, without opening
the  top  drawer, by taking off a screw  in front  and poking around with  a
piece of hanger wire.
     I  tried spinning the combination wheel very rapidly and then going  to
ten, thus putting a little friction on, which I hoped would stop a  disc  at
the  right  point in  some  manner.  I  tried  all kinds  of  things. I  was
desperate.
     I also  did a certain  amount  of  systematic  study.  For  instance, a
typical combination  was 69-32-21. How far off could a number be when you're
opening the safe? If the number was 69, would 68 work? Would 67 work? On the
particular locks we had, the answer was yes for  both, but 66 wouldn't work.
You could be  off by two in either direction. That meant you only had to try
one out of five  numbers, so you could try  zero, five, ten, fifteen, and so
on. With twenty such numbers on  a wheel of 100, that was 8000 possibilities
instead of the 1,000,000 you  would  get  if  you had  to  try  every single
number.
     Now  the question  was, how  long  would  it take me  to try  the  8000
combinations? Suppose I've got the first two numbers  right of a combination
I'm trying to  get. Say  the numbers are 69-32,  but I don't know it -- I've
got  them as  70-30. Now I can try the twenty possible third numbers without
having to  set up the first  two numbers each time. Now let's suppose I have
only the first  number of the combination right.  After  trying  the  twenty
numbers on the third disc,  I move the  second wheel only a little bit,  and
then do another twenty numbers on the third wheel.
     I practiced  all the time on my own safe so I could  do this process as
fast as I could and not get lost in my mind as to which number I was pushing
and mess up the first  number. Like a guy  who  practices sleight of hand, I
got it  down  to  an absolute  rhythm so I could try the  400 possible  back
numbers in  less  than half an hour.  That meant I could  open a  safe  in a
maximum of eight hours -- with an average time of four hours.
     There was  another guy there at Los  Alamos named  Staley who  was also
interested in locks. We talked about it from  time to time,  but we  weren't
getting  anywhere  much. After I  got this  idea how  to  open a safe  in an
average  time of four hours, I wanted to show Staley how to do it, so I went
into a guy's office over in the computing department and asked, "Do you mind
if I use your safe? I'd like to show Staley something."
     Meanwhile some guys  in the computing department came around and one of
them  said, "Hey, everybody; Feynman's gonna show Staley how to open a safe,
ha,  ha, ha!" I wasn't going to  actually open the safe; I was just going to
show Staley this way of quickly trying the back  two numbers  without losing
your place and having to set up the first number again.
     I  began. "Let's  suppose  that the first number is  forty,  and  we're
trying fifteen for the second number. We go back and  forth, ten;  back five
more  and  forth, ten; and so on.  Now we've  tried all  the  possible third
numbers. Now we try twenty for the second number: we go back and forth, ten;
back five  more  and forth, ten;  back five  more and forth, CLICK!"  My jaw
dropped: the first and second numbers happened to be right!
     Nobody  saw my  expression  because  my  back was towards  them. Staley
looked very surprised, but  both of us caught  on  very quickly as  to  what
happened, so I pulled  the  top drawer out  with a flourish  and  said, "And
there you are!"
     Staley said, "I see  what  you mean; it's a very good scheme" -- and we
walked out. Everybody was amazed. It  was complete  luck. Now I really had a
reputation for opening safes.
     It took me  about a year and a half to get that far (of course,  I  was
working on the bomb, too!) but I figured that I had the safes beaten, in the
sense that if there was a real  difficulty -- if somebody was lost, or dead,
and nobody else knew the combination but the stuff in the filing cabinet was
needed  --  I  could open  it.  After  reading what preposterous  things the
safecrackers   claimed,   I  thought   that   was   a   rather   respectable
accomplishment.
     We had no  entertainment  there  at Los Alamos,  and  we had  to  amuse
ourselves somehow, so fiddling with the Mosler lock on my filing cabinet was
one of my  entertainments. One  day I made an interesting observation:  When
the lock is opened and the drawer  has been pulled out and the wheel is left
on ten (which is what people do when they've opened their filing cabinet and
are  taking  papers out of it), the bolt  is still  down. Now what does that
mean, the bolt is still down? It  means the bolt is  in the slot made by the
three discs, which are still properly lined up. Ahhhh!
     Now, if I turn the wheel away from ten a little bit, the bolt comes up;
if  I immediately go back to ten,  the bolt goes back down  again, because I
haven't  yet disturbed the  slot. If I keep going away from ten in steps  of
five, at some point the  bolt won't go back  down when I go back to ten: the
slot has just  been disturbed. The number  just  before, which still let the
bolt go down, is the last number of the combination!
     I realized that I could do the same thing to find the second number: As
soon as I know the  last  number, I can turn the wheel around the  other way
and again, in lumps of  five, push the second disc bit by bit until the bolt
doesn't go down. The number just before would be the second number.
     If  I were very patient I would be able  to  pick up all three  numbers
that way, but the amount of work involved in picking up the  first number of
the combination by this elaborate scheme would be much more than just trying
the  twenty  possible  first  numbers with  the other two  numbers that  you
already know, when the filing cabinet is closed.
     I practiced and I  practiced until I could get the last two numbers off
an  open filing  cabinet, hardly looking at the dial.  Then, when I'd  be in
some guy's office discussing  some  physics  problem,  I'd lean against  his
opened  filing  cabinet,   and  just  like   a   guy  who's   jiggling  keys
absent-mindedly while he's talking, I'd just wobble the dial back and forth,
back and forth.  Sometimes I'd put my finger  on the bolt so I wouldn't have
to look to see if it's coming up.  In this way  I  picked off the  last  two
numbers  of various filing cabinets. When I got  back to  my office  I would
write  the two numbers down on a piece of  paper that I kept inside the lock
of my filing cabinet. I  took the lock apart each time to get the paper -- I
thought that was a very safe place for them.
     After  a while my reputation  began  to sail, because things  like this
would happen:  Somebody would say, "Hey, Feynman! Christy's out of town  and
we need a document from his safe -- can you open it?"
     If it was a safe I knew I didn't  have the last two numbers of, I would
simply say, "I'm sorry, but I can't do it  now;  I've  got this work  that I
have to do." Otherwise, I would  say, "Yeah, but  I  gotta get  my tools." I
didn't need any tools, but I'd go back to my office, open my filing cabinet,
and look at  my little piece of paper: "Christy --  35, 60." Then  I'd get a
screwdriver  and go  over  to Christy's office and close the door behind me.
Obviously not everybody is supposed to be allowed to know how to do this!
     I'd be in there alone and I'd open the safe in a few minutes. All I had
to  do  was  try  the first  number at most twenty times,  then sit  around,
reading a magazine or something, for fifteen or twenty minutes. There was no
use trying to make it look too easy; somebody would figure  out  there was a
trick to it! After a while I'd open the door and say, "It's open."
     People  thought  I  was  opening the  safes  from scratch. Now  I could
maintain the idea, which began with that accident with Staley, that  I could
open safes cold. Nobody figured out that I was picking the last two  numbers
off their safes, even though  -- perhaps because  -- I  was doing it all the
time, like a card sharp walking around all the time with a deck of cards.
     I often went  to Oak Ridge  to  check up on  the safety of  the uranium
plant. Everything was always in a hurry because it was wartime, and one time
I had to go there on a weekend. It was Sunday, and  we were in this  fella's
office -- a general, a head or a vice president of some company, a couple of
other big  muck-a-mucks, and  me. We were  gathered  together  to  discuss a
report that  was  in the fella's  safe -- a secret safe  -- when suddenly he
realized that he didn't know the combination. His secretary was the only one
who knew it,  so he  called  her home and it turned out she  had  gone on  a
picnic up in the hills.
     While all this was going on, I asked, "Do you mind if I fiddle with the
safe?"
     "Ha,  ha, ha -- not at all!" So I went over to  the safe and started to
fool around.
     They began to  discuss how they could  get a  car  to try to  find  the
secretary, and the  guy was getting more and more embarrassed because he had
all these people waiting and  he  was such  a jackass he didn't  know how to
open  his own safe. Everybody  was all  tense  and getting mad at him,  when
CLICK! -- the safe opened.
     In  10  minutes I  had opened  the safe that  contained all  the secret
documents about the  plant. They were astonished. The safes  were apparently
not very safe. It was  a terrible  shock: All  this "eyes  only" stuff,  top
secret, locked in  this wonderful secret safe,  and this guy opens it in ten
minutes! Of course I was able to open the safe because of my perpetual habit
of taking the last two numbers  off. While in Oak Ridge the month  before, I
was in the  same office when the safe was open and I took the numbers off in
an  absent-minded way -- I  was  always practicing my obsession.  Although I
hadn't written them down,  I was able  to vaguely  remember  what they were.
First I tried 40-15, then 15-40,  but neither of those  worked. Then I tried
10-45 with all the first numbers, and it opened.
     A  similar thing  happened on another weekend  when I  was visiting Oak
Ridge. I had written a report that had  to be OKed by a  colonel, and it was
in his safe. Everybody else keeps documents in filing cabinets like the ones
at Los Alamos, but he was a colonel, so he had a much fancier, two-door safe
with big handles that pull four  3/4-inch-thick steel bolts from  the frame.
The great brass doors swung open and he took out my report to read.
     Not having had an opportunity to  see  any really good safes, I said to
him, "Would you mind,  while you're  reading my  report, if I looked at your
safe?"
     "Go right ahead," he said, convinced that there was nothing I could do.
I looked at the back of one of  the solid brass doors, and I discovered that
the combination wheel was connected to a little lock that looked exactly the
same as the little  unit that was on my filing cabinet at Los  Alamos.  Same
company, same  little bolt, except  that when the bolt  came down,  the  big
handles on the safe could then move  some rods sideways, and with a bunch of
levers  you could pull back all those 3/4-inch  steel rods.  The whole lever
system, it  appeared, depends on  the  same little bolt  that  locks  filing
cabinets.
     Just for the sake of professional  perfection, to make  sure it was the
same, I took the two numbers off the same way I  did with the filing cabinet
safes.
     Meanwhile, he was reading the  report. When he'd finished he said, "All
right,  it's fine." He put the report in the safe, grabbed  the big handles,
and swung the great brass doors together. It sounds so good when they close,
but I know  it's all psychological,  because  it's nothing but the same damn
lock.
     I couldn't help but needle him a little bit (I always had a thing about
military guys, in  such wonderful  uniforms)  so I said, "The  way you close
that safe, I get the idea that you think things are safe in there."
     "Of course."
     "The only  reason you  think they're safe in there is because civilians
call it a 'safe.' " (I put the word "civilians" in there to make it sound as
if he'd been had by civilians.)
     He got very angry. "What do you mean -- it's not safe?"
     "A good safecracker could open it in thirty minutes."
     "Can you open it in thirty minutes?"
     "I said a good safecracker. It would take me about forty-five."
     "Well!" he said. "My wife is waiting  at home for me  with supper,  but
I'm gonna stay here and watch you, and  you're gonna sit down there and work
on that  damn thing for forty-five minutes and not open  it!" He sat down in
his big leather chair, put his feet up on his desk, and read.
     With complete confidence  I picked up a  chair, carried it  over to the
safe and sat down in front of it. I began to turn the  wheel at random, just
to make some action.
     After  about five minutes, which is quite  a long time when you're just
sitting  and waiting,  he lost  some  patience:  "Well,  are you  making any
progress?"
     "With a thing like this, you either open it or you don't."
     I  figured one or two  more minutes would be about time, so I  began to
work in earnest and two minutes later, CLINK -- it opened.
     The colonel's jaw dropped and his eyes  bugged  out. "Colonel," I said,
in a serious tone, "let  me  tell you  something about these locks: When the
door to the safe or the top drawer of the filing  cabinet is left open, it's
very easy  for someone  to get the combination. That's what I did while  you
were reading my  report, just to  demonstrate  the danger. You should insist
that  everybody  keep  their filing  cabinet  drawers locked  while  they're
working, because when they're open, they're very, very vulnerable."
     "Yeah! I see what you mean! That's  very interesting!"  We were  on the
same side after that.
     The next time  I went to Oak Ridge, all  the secretaries and people who
knew who I was were telling me, "Don't come through here! Don't come through
here!"
     The colonel had sent a note around to everyone in the plant which said,
"During his last visit, was  Mr. Feynman  at  any time in  your office, near
your office,  or walking through your  office?"  Some  people answered  yes;
others said  no. The ones  who said yes got another note: "Please change the
combination of your safe."
     That  was his solution: I was  the danger. So they  all  had to  change
their combinations on  account of me.  It's a pain in the  neck to change  a
combination and remember the new one, so they were all mad  at me and didn't
want me to  come near them: they might have to change their combination once
again. Of course, their filing cabinets were still left open while they were
working!
     A  library at Los Alamos held all of the documents we  had ever  worked
on: It  was  a  solid,  concrete room with a big, beautiful door which had a
metal wheel that  turns  --  like a safe-deposit vault. During the war I had
tried to  look at  it closely. I  knew the girl who was the librarian, and I
begged her to let me play  with it a little bit. I was fascinated by  it: it
was the  biggest  lock I ever saw! I  discovered that  I could never use  my
method of picking off the last two numbers to get in. In fact, while turning
the  knob while the door was open, I made the lock close, so it was sticking
out, and they couldn't close  the door again until the  girl came and opened
the lock again.  That was  the end of my  fiddling around  with that lock. I
didn't  have  time to  figure  out  how it worked;  it  was  much  beyond my
capacity.
     During the summer after  the war I had some documents to write and work
to finish up,  so I went back to Los Alamos from Cornell, where I had taught
during the year. In the middle of my work I had  to refer to a document that
I had written before but couldn't remember, and it was down in the library.
     I went down to get the document, and  there was  a soldier walking back
and forth, with a gun. It was a  Saturday, and after the war the library was
closed on Saturdays.
     Then I remembered what a good friend of mine, Frederic de Hoffman,  had
done. He  was in  the Declassification Section. After  the war the army  was
thinking of declassifying some documents, and he had to go back and forth to
the library so much -- look at this document,  look  at that document, check
this, check that --  that  he was going  nuts!  So he  had a  copy of  every
document -- all the secrets to the atomic bomb -- in nine filing cabinets in
his office.
     I went  down  to his office, and the lights  were  on. It  looked as if
whoever was there -- perhaps his secretary -- had just stepped out for a few
minutes,  so I waited. While I  was waiting I started to  fiddle around with
the combination  wheel on one of the filing cabinets. (By  the way, I didn't
have the last two numbers for de Hoffman's safes; they were put in after the
war, after I had left.)
     I started to play with one of the combination wheels and began to think
about  the  safecracker books.  I thought to  myself, "I've never  been much
impressed by the tricks described in those books, so I've never tried  them,
but let's see if we can open de Hoffman's safe by following the book."
     First  trick,  the secretary:  she's  afraid she's  going to forget the
combination, so  she writes  it down somewhere. I started to look in some of
the places  mentioned in the book. The desk drawer was locked, but it was an
ordinary lock like Leo Lavatelli taught me how to open -- ping! I look along
the edge: nothing.
     Then I looked through the secretary's  papers. I found a sheet of paper
that all the secretaries had,  with the  Greek  letters carefully made -- so
they could recognize them  in mathematical formulas -- and named. And there,
carelessly written along the top of the paper, was pi = 3.14159. Now, that's
six digits, and why does a secretary have to know the numerical value of pi?
It was obvious; there was no other reason!
     I went over to the filing cabinets  and tried the  first one: 31-41-59.
It didn't open.  Then  I  tried  59-41-31. That  didn't  work  either.  Then
95-14-13. Backwards,  forwards, upside down, turn  it this way, turn it that
-- nothing!
     I closed  the desk drawer and  started to walk  out  the door,  when  I
thought of the safecracker books again:  Next, try the  psychology method. I
said  to  myself,  "Freddy de Hoffman  is just  the  kind  of guy  to  use a
mathematical constant for a safe combination."
     I went back to the first filing cabinet and tried 27-18-28 -- CLICK! It
opened! (The mathematical constant second in importance to pi is the base of
natural logarithms, e:2.71828...) There were nine filing cabinets, and I had
opened the  first one, but the document I wanted was  in another one -- they
were in  alphabetical order by  author. I tried the  second filing  cabinet:
27-18-28 -- CLICK! It opened with the same, combination. I thought, "This is
wonderful! I've opened the secrets to the atomic bomb, but if I'm ever going
to  tell  this story, I've  got to make  sure that  all the combinations are
really the  same!" Some of the filing cabinets were  in  the next room, so I
tried 27-18-28 on one of them, and it opened.  Now I'd opened three safes --
all the same.
     I thought to myself, "Now I could write  a  safecracker book that would
beat  every one, because at the beginning I would  tell how  I  opened safes
whose  contents  were bigger  and more  valuable  than  what any safecracker
anywhere  had opened -- except for a life, of course -- but compared  to the
furs  or  the gold bullion, I have them  all beat: I opened the safes  which
contained  all  the secrets  to  the  atomic  bomb:  the  schedules for  the
production  of the plutonium, the purification procedures, how much material
is needed,  how the bomb  works, how  the  neutrons  are generated, what the
design  is, the dimensions -- the entire  information that was  known at Los
Alamos: the whole shmeer!"
     I went  back to  the second filing  cabinet and took out the document I
wanted. Then I took a red grease pencil and a piece of yellow paper that was
lying around in the  office and  wrote,  "I borrowed  document no. LA4312 --
Feynman the safe-cracker." I put the note on top of the papers in the filing
cabinet and closed it.
     Then I went to the first one I had opened and wrote another note: "This
one was no  harder  to open than the other  one -- Wise  Guy" and  shut  the
cabinet.
     Then in the  other  cabinet,  in  the  other  room, I wrote, "When  the
combinations are all the same, one is no harder to open than another -- Same
Guy" and I shut that one. I went back to my office and wrote my report.
     That evening  I went to the cafeteria and ate supper.  There was Freddy
de Hoffman. He said he was going over to his office to work, so just for fun
I went with him.
     He started to work, and soon he went into the other room to open one of
the  filing cabinets in  there -- something  I hadn't counted  on  -- and he
happened to open the filing  cabinet I had put the third note in,  first. He
opened the  drawer, and  he saw this foreign object in there --  this bright
yellow paper with something scrawled on it in bright red crayon.
     I had read in books that when somebody is afraid, his face gets sallow,
but I had never seen it  before. Well, it's absolutely true. His face turned
a gray, yellow green -- it was really frightening to see. He  picked  up the
paper, and his hand was shaking. "L-l-look at this!" he said, trembling.
     The note said, "When  the  combinations are all the  same,  one  is  no
harder to open than another -- Same Guy."
     "What does it mean?" I said.
     "All the c-c-combinations of my safes are the s-s-same!" he stammered.
     "That ain't such a good idea."
     "I-I know that n-now!" he said, completely shaken.
     Another effect of the blood draining  from the  face must  be  that the
brain doesn't  work right. "He signed who  it was! He signed who it was!" he
said.
     "What?" (I hadn't put my name on that one.)
     "Yes,"  he  said,  "it's the same  guy  who's  been  trying to get into
Building Omega!"
     All during the war, and  even after, there were these perpetual rumors:
"Somebody's been trying to get into Building Omega!" You see, during the war
they were doing experiments for the bomb in which  they wanted to get enough
material together for  the chain  reaction to  just get started.  They would
drop one  piece of material  through  another, and when it went through, the
reaction  would start  and they'd measure how many  neutrons  they  got. The
piece would  fall through so  fast that nothing should build up and explode.
Enough of  a reaction would begin, however,  so they could tell that  things
were really starting correctly, that the  rates were  right, and  everything
was going according to prediction -- a very dangerous experiment!
     Naturally, they were  not  doing this experiment in  the middle of  Los
Alamos, but off several miles, in a canyon several mesas over, all isolated.
This  Building Omega had its  own fence around it with guard towers. In  the
middle of the night when  everything's  quiet, some  rabbit comes out of the
brush and smashes against the fence and makes a noise. The guard shoots. The
lieutenant in charge comes  around. What's the guard going to say -- that it
was  only  a rabbit?  No. "Somebody's been trying to get into Building Omega
and I scared him off!"
     So de Hoffman was pale and shaking,  and he didn't  realize there was a
flaw in  his logic: it was not clear that the same guy  who'd been trying to
get into  Building Omega  was the same guy who was standing next  to him. He
asked me what to do. "Well, see if any documents are missing." "It looks all
right," he said.  "I don't see  any missing." I tried  to  steer  him to the
filing cabinet I took my document out of. "Well, uh, if all the combinations
are the same, perhaps he's taken something from another drawer."
     "Right!" he said, and he went back into his office and opened the first
filing  cabinet and found the second note I wrote: "This  one  was no harder
than the other one -- Wise Guy."
     By that time it didn't make any difference whether it was "Same Guy" or
"Wise Guy": It was  completely  clear to  him that it  was the  guy  who was
trying to  get into Building Omega. So  to convince  him to open  the filing
cabinet with  my first  note in it was  particularly difficult, and I  don't
remember how I talked him into it.
     He started to  open it, so I began to walk down the hall, because I was
a little bit afraid that when he found out who did it to him, I was going to
get my throat cut!
     Sure enough,  he came  running down  the hall after me,  but instead of
being angry, he  practically  put  his  arms  around  me  because he was  so
completely  relieved that  this terrible burden  of the atomic secrets being
stolen was only me doing mischief.
     A few days later  de  Hoffman  told me  that  he needed something  from
Kerst's safe. Donald Kerst had gone back to Illinois and was hard to  reach.
"If you can open  all  my  safes using the psychological method," de Hoffman
said (I had told him how I did it),  "maybe you could open Kerst's safe that
way."
     By now the story  had gotten around, so several  people  came  to watch
this fantastic process where I was going to open Kerst's safe -- cold. There
was no need for  me  to be alone.  I  didn't  have the last two  numbers  to
Kerst's safe, and to use the  psychology method I  needed people  around who
knew Kerst.
     We all went over to Kerst's office and I checked the drawers for clues;
there was nothing.  Then  I asked them, "What kind  of a  combination  would
Kerst use -- a mathematical constant?"
     "Oh, no!" de Hoffman said. "Kerst would do something very simple."
     I tried 10-20-30, 20-40-60, 60-40-20, 30-20-10. Nothing.
     Then I said, "Do you think he would use a date?"
     "Yeah!" they said. "He's just the kind of guy to use a date."
     We tried various  dates: 8-6-45, when the bomb went off; 86-19-45; this
date; that date; when the project started. Nothing worked.
     By this time most  of the people  had drifted off. They didn't have the
patience to  watch me  do this, but  the  only way to solve such a  thing is
patience!
     Then  I  decided to try everything  from around  1900  until now.  That
sounds  like a  lot, but it's not: the first number is a month, one  through
twelve, and I can  try  that using only three numbers: ten, five, and  zero.
The second number is a day, from one to thirty-one, which I can try with six
numbers. The third number is the year, which was only forty-seven numbers at
that time, which I could try with nine numbers. So the 8000 combinations had
been reduced to 162, something I could try in fifteen or twenty minutes.
     Unfortunately I  started with the  high  end  of  the  numbers for  the
months, because when I finally opened it, the combination was 0-5-35.
     I  turned to de  Hoffman.  "What happened  to Kerst  around  January 5,
1935?"
     "His daughter  was born in  1936,"  de Hoffman  said. "It must  be  her
birthday."
     Now  I had  opened  two  safes  cold. I  was getting  good.  Now  I was
professional.
     That same summer after the war, the guy  from the  property section was
trying  to take back some  of the things  the government had bought, to sell
again as surplus. One  of the things was a Captain's safe. We all knew about
this  safe.  The Captain,  when he arrived  during the war, decided that the
filing cabinets weren't safe enough for the secrets he was going  to get, so
he had to have a special safe.
     The  Captain's  office was on  the second floor  of  one of  the flimsy
wooden buildings that we all had our offices in, and the safe he ordered was
a heavy steel  safe. The workmen had to put  down platforms of  wood and use
special  jacks to get it up the steps. Since there wasn't much amusement, we
all  watched this big safe being moved  up to his office with great  effort,
and we all made  jokes  about what  kind of secrets  he was going to keep in
there. Some fella said we oughta put our stuff in his safe, and  let him put
his stuff in ours. So everyone knew about this safe.
     The property section man wanted it for Surplus, but first it had to  be
emptied, and the only people who knew the combination were  the Captain, who
was in Bikini, and Alvarez, who'd forgotten it. The man asked me to open it.
     I went up to his old office and said to the  secretary,  "Why don't you
phone the Captain and ask him the combination?"
     "I don't want to bother him," she said.
     "Well, you're  gonna bother  me  for maybe eight  hours. I won't do  it
unless you make an attempt to call him."
     "OK, OK!" she said.  She picked  up the telephone  and  I went into the
other room to look at the safe. There it was, that huge, steel safe, and its
doors were wide open.
     I went back to the secretary. "It's open."
     "Marvelous!" she said, as she put down the phone.
     "No," I said, "it was already open."
     "Oh! I guess the property section was able to open it after all."
     I went down to the man in the property section.  "I went up to the safe
and it was already open."
     "Oh,  yeah," he said; "I'm sorry I didn't tell you. I  sent our regular
locksmith  up there to  drill it, but before he  drilled it he tried to open
it, and he opened it."
     So! First information: Los Alamos now has  a regular  locksmith. Second
information: This man knows how to  drill safes, something  I  know  nothing
about. Third information:
     He  can  open  a  safe  cold  --  in a  few  minutes.  This is  a  real
professional, a real source of information. This guy I have to meet.
     I found out he was a locksmith they had hired after the  war (when they
weren't as concerned about security) to take  care of such things. It turned
out that he didn't have enough work to do opening safes, so he also repaired
the Marchant calculators we had used. During the war I repaired those things
all the time -- so I had a way to meet him.
     Now I have never been surreptitious or tricky about meeting somebody; I
just go right up and introduce myself. But in this case it  was so important
to meet this man, and I knew that before he would tell me any of his secrets
on how to open safes, I would have to prove myself.
     I  found out where his room was -- in  the  basement of the theoretical
physics section, where I worked -- and I knew he worked in the evening, when
the machines weren't being used. So, at first I would walk past  his door on
my way to my office in the evening. That's all; I'd just walk past.
     A few nights later, just a "Hi." After a while, when he saw it was  the
same guy walking past, he'd say "Hi," or "Good evening."
     A few weeks of this slow process and I see he's working on the Marchant
calculators. I say nothing about them; it isn't time yet.
     We gradually say a little more: "Hi! I see you're working pretty hard!"
     "Yeah, pretty hard" -- that kind of stuff.
     Finally, a  breakthrough: he invites me for  soup. It's going very good
now.  Every evening  we have soup together. Now I begin to talk a little bit
about the adding machines, and  he  tells me  he has  a problem.  He's  been
trying to put a succession of spring-loaded wheels back onto a shaft, and he
doesn't have  the right tool,  or something; he's  been working  on it for a
week. I tell him that I  used to work on those machines  during the war, and
"I'll tell you what: you just leave the machine out tonight, and I'll have a
look at it tomorrow."
     "OK," he says, because he's desperate.
     The next day I looked at the damn thing and tried to load it by holding
all the wheels in my hand. It kept snapping back. I thought to  myself,  "If
he's been trying the same thing  for a week, and I'm trying it and can't  do
it, it  ain't the way to do  it!" I stopped and looked at it very carefully,
and  I noticed that each wheel had a little hole -- just a little hole. Then
it dawned on me: I sprung the first one; then I put a piece of  wire through
the little hole. Then I sprung the second  one and put the wire through  it.
Then the next one, the next one  -- like putting beads on a string  -- and I
strung the whole thing the first time I tried it, got it all in line, pulled
the wire out, and everything was OK.
     That night I showed him the little hole and how I did it, and from then
on we talked  a lot  about machines; we  got to be good friends. Now, in his
office there were a lot of little cubbyholes that contained locks half taken
apart,  and pieces from safes,  too. Oh, they were  beautiful! But  I  still
didn't say a word about locks and safes.
     Finally, I figured the day was coming, so I decided to put out a little
bit of  bait  about safes: I'd tell  him the only thing worth  a damn that I
knew about  them  -- that you can take the last  two numbers off  while it's
open. "Hey!" I said,  looking over at the  cubbyholes. "I see you're working
on Mosler safes."
     "Yeah."
     "You know, these locks are weak. If they're open, you can take the last
two numbers off..."
     "You can?" he said, finally showing some interest.
     "Yeah."
     "Show me how," he said. I showed him how to do it, and he turned to me.
"What's your name?" All this time we had never exchanged names.
     "Dick Feynman," I said.
     "God! You're Feynman!"  he  said  in awe. "The great safecracker!  I've
heard about you; I've wanted to meet you for so long! I want to learn how to
crack a safe from you."
     "What do you mean? You know how to open safes cold."
     "I don't."
     "Listen, I heard about the Captain's safe, and I've been working pretty
hard all  this time because I wanted to meet  you. And you tell me you don't
know how to open a safe cold."
     "That's right."
     "Well you must know how to drill a safe."
     "I don't know how to do that either."
     "WHAT?" I exclaimed. "The guy in the property  section said  you picked
up your tools and went up to drill the Captain's safe."
     "Suppose you had a job as  a locksmith," he said, "and a guy comes down
and asks you to drill a safe. What would you do?"
     "Well,"  I  replied,  "I'd make a  fancy  thing  of  putting  my  tools
together, pick them up and take them to the safe. Then  I'd put  my drill up
against the safe somewhere at random  and I'd go vvvvvvvvvvv, so I'd save my
job."
     "That's exactly what I was going to do."
     "But you opened it! You must know how to crack safes."
     "Oh, yeah. I knew that the locks come  from  the factory set at 25-0-25
or 50-25-50, so I thought, 'Who knows; maybe the guy didn't bother to change
the combination,' and the second one worked."
     So I did learn something  from him -- that he cracked safes by the same
miraculous methods  that I  did.  But even funnier was  that  this  big shot
Captain had  to have  a super, super safe, and  had people  go  to all  that
trouble to hoist the thing  up into his office, and he didn't even bother to
set the combination.
     I went  from office to office in my building, trying those  two factory
combinations, and I opened about one safe in five.


--------
Uncle Sam Doesn't Need You!

     After the war the army was scraping the bottom of the barrel to get the
guys for the  occupation forces in Germany. Up until then  the army deferred
people for some reason other than  physical first (I was deferred because  I
was working on the bomb), but now they reversed  that and gave  everybody  a
physical first.
     That  summer I  was working  for  Hans  Bethe  at General  Electric  in
Schenectady,  New  York, and I remember that I had to go some distance --  I
think it was to Albany -- to take the physical.
     I get to  the draft place, and I'm handed  a lot  of forms to fill out,
and then I start going around to all these different booths. They check your
vision at  one, your  hearing  at another, they take  your blood  sample  at
another, and so forth.
     Anyway, finally you  come to booth number thirteen: psychiatrist. There
you wait,  sitting on one of the  benches,  and while I'm waiting I  can see
what is happening.  There are three  desks, with  a psychiatrist behind each
one, and  the "culprit" sits across  from the psychiatrist in  his  BVDs and
answers various questions.
     At that  time there  were  a  lot of movies  about  psychiatrists.  For
example, there was Spellbound, in which a woman who used to be a great piano
player has her hands stuck in some awkward position and she can't move them,
and  her  family  calls  in  a psychiatrist  to  try to  help her,  and  the
psychiatrist goes upstairs into a room  with her, and you see the door close
behind them, and downstairs the family is discussing what's going to happen,
and then  she  comes  out  of  the room, hands still stuck  in  the horrible
position,  walks dramatically down the stairs  over  to  the piano  and sits
down, lifts  her hands  over the keyboard,  and suddenly --  dum  diddle dum
diddle dum, dum, dum -- she can play again. Well, I can't stand this kind of
baloney,  and I had decided  that psychiatrists are  fakers, and  I'll  have
nothing to  do with them. So that was the mood I was in  when it was my turn
to talk to the psychiatrist.
     I sit down at the desk, and the psychiatrist starts  looking through my
papers. "Hello, Dick!" he says in a cheerful voice. "Where do you work?"
     I'm thinking,  "Who does he think he is, calling me  by my first name?"
and I say coldly, "Schenectady."
     "Who do you work for, Dick?" says the psychiatrist, smiling again.
     "General Electric."
     "Do you like your work, Dick?" he says, with that same big smile on his
face.
     "So-so." I just wasn't going to have anything to do with him.
     Three  nice questions, and then the fourth one is completely different.
"Do you think people talk about you?" he asks, in a low, serious tone.
     I light up and say, "Sure! When I go home, my mother often tells me how
she  was  telling  her  friends  about   me."  He  isn't  listening  to  the
explanation; instead, he's writing something down on my paper.
     Then again, in a low, serious tone, he says, "Do you think people stare
at you?"
     I'm all ready to say no, when he says, ''For instance, do you think any
of the boys waiting on the benches are staring at you now?"
     While  I had been waiting  to talk  to the psychiatrist, I had  noticed
there  were  about  twelve  guys  on  the  benches  waiting  for  the  three
psychiatrists, and they've got nothing  else to  look at, so I divide twelve
by three -- that makes four each --  but I'm conservative, so I say,  "Yeah,
maybe two of them are looking at us."
     He  says,  "Well just  turn around  and  look"  --  and  he's not  even
bothering to look himself!
     So I turn around, and sure enough, two guys are looking. So I  point to
them and I say, "Yeah --  there's that guy, and that guy  over there looking
at us." Of course, when I'm turned around and pointing like that, other guys
start to look at us, so I say, "Now him, and those two over there -- and now
the  whole bunch." He still doesn't look up to check. He's busy writing more
things on my paper.
     Then he says, "Do you ever hear voices in your head?"
     "Very rarely," and I'm about  to describe the two occasions on which it
happened when he says, "Do you talk to yourself?"
     "Yeah, sometimes when I'm  shaving, or thinking; once in a while." He's
writing down more stuff.
     "I see you have a deceased wife -- do you talk to her?"
     This  question  really  annoyed  me, but I  contained myself and  said,
"Sometimes, when I go up on a mountain and I'm thinking about her."
     More  writing.  Then he asks,  "Is  anyone  in  your family in a mental
institution?"
     "Yeah, I have an aunt in an insane asylum."
     "Why do you call it an insane asylum?" he says, resentfully. "Why don't
you call it a mental institution?"
     "I thought it was the same thing."
     "Just what do you think insanity is?" he says, angrily.
     "It's a strange and peculiar disease in human beings," I say honestly.
     "There's  nothing  any  more  strange   or  peculiar   about  it   than
appendicitis!" he retorts.
     "I don't think so. In appendicitis we understand the causes better, and
something about the mechanism of it, whereas with  insanity it's  much  more
complicated and mysterious."  I won't go through the whole debate; the point
is that I meant insanity is physiologically peculiar, and he thought I meant
it was socially peculiar.
     Up until this time, although I had been unfriendly to the psychiatrist,
I had nevertheless been honest in everything I said. But when he asked me to
put  out  my  hands,  I  couldn't  resist pulling  a  trick  a  guy  in  the
"bloodsucking  line" had told  me about. I figured nobody was ever going  to
get a chance to do this,  and as long as I was halfway  under water, I would
do it. So I put out my hands with one palm up and the other one down.
     The psychiatrist doesn't notice. He says, "Turn them over."
     I turn them  over.  The one that was up goes down, and the one that was
down goes up, and he still doesn't notice, because  he's always looking very
closely at one hand to see if it is shaking. So the trick had no effect.
     Finally, at the end  of all these questions, he becomes friendly again.
He lights up and says, "I see you have a Ph.D., Dick. Where did you study?"
     "MIT and Princeton. And where did you study?"
     "Yale and London. And what did you study, Dick?"
     "Physics. And what did you study?"
     "Medicine."
     "And this is medicine?"
     "Well, yes. What do you think it is? You go and sit down over there and
wait a few minutes!"
     So I sit on  the bench again, and  one of the other guys waiting sidles
up to me and says, "Gee! You  were in there twenty-five minutes!  The  other
guys were in there only five minutes!"
     "Yeah."
     "Hey," he  says. "You wanna know how  to fool the psychiatrist? All you
have to do is pick your nails, like this."
     "Then why don't you pick your nails like that?"
     "Oh," he says, "I wanna get in the army!"
     "You wanna fool the psychiatrist?" I say. "You just tell him that!"
     After a  while I was called over  to  a  different desk to see  another
psychiatrist.  While  the  first psychiatrist  had  been  rather  young  and
innocent-looking,  this  one  was  gray-haired and distinguished-looking  --
obviously the superior psychiatrist. I  figure  all of this is now  going to
get straightened  out, but no matter  what happens, I'm not going  to become
friendly.
     The new psychiatrist looks at  my papers, puts a big smile on his face,
and says, "Hello, Dick. I see you worked at Los Alamos during the war."
     "Yeah."
     "There used to be a boys' school there, didn't there?"
     "That's right."
     "Were there a lot of buildings in the school?"
     "Only a few."
     Three  questions  --  same  technique  --  and  the  next  question  is
completely different. "You said you hear voices in your head. Describe that,
please."
     "It  happens very rarely, when I've been  paying attention to  a person
with  a  foreign accent.  As I'm falling  asleep  I can hear his voice  very
clearly. The first time it happened was  while I  was  a student  at MIT.  I
could hear  old Professor  Vallarta say, 'Dee-a dee-a electric field-a.' And
the other time  was  in Chicago  during the  war, when Professor  Teller was
explaining to me how the bomb worked.  Since I'm  interested in all kinds of
phenomena,  I  wondered  how  I  could hear  these  voices  with accents  so
precisely, when I couldn't imitate them that well... Doesn't  everybody have
something like that happen once in a while?"
     The psychiatrist put  his hand  over his face, and I could  see through
his fingers a little smile (he wouldn't answer the question).
     Then  the psychiatrist checked into something  else. "You said that you
talk to your deceased wife. What do you say to her?"
     I got angry.  I figure it's none of  his  damn business,  and I say, "I
tell her I love her, if it's all right with you!"
     After  some  more bitter  exchanges  he says,  "Do  you  believe in the
supernormal?"
     I say, "I don't know what the 'supernormal' is."
     "What? You, a Ph.D. in physics, don't know what the supernormal is?"
     "That's right."
     "It's what Sir Oliver Lodge and his school believe in."
     That's not much of a clue, but I knew it. "You mean the supernatural."
     "You can call it that if you want."
     "All right, I will."
     "Do you believe in mental telepathy?"
     "No. Do you?"
     "Well, I'm keeping an open mind."
     "What? You, a psychiatrist, keeping an open mind? Ha!" It  went on like
this for quite a while.
     Then at some point near the end he says, "How much do you value life?"
     "Sixty-four."
     "Why did you say 'sixty-four'?"
     "How are you supposed to measure the value of life?"
     "No! I mean, why did you say 'sixty-four,' and not 'seventy-three,' for
instance?"
     "If  I  had said  'seventy-three,'  you  would have asked  me the  same
question!"
     The  psychiatrist finished  with three friendly questions, just  as the
other psychiatrist had done, handed me my papers, and I went off to the next
booth.
     While  I'm  waiting  in  the line, I look at the  paper which  has  the
summary of  all  the tests I've taken  so far. And just for the hell of it I
show  my  paper  to  the  guy  next  to  me,  and  I  ask  him in  a  rather
stupid-sounding voice, "Hey! What did you get in  'Psychiatric'? Oh! You got
an 'N.'  I got an 'N' in everything else, but I got a 'D'  in 'Psychiatric.'
What does that mean?" I knew what it meant: "N" is normal, "D" is deficient.
     The guy pats  me on the shoulder and says, "Buddy, it's  perfectly  all
right.  It doesn't  mean anything. Don't worry about it!" Then he  walks way
over to the other corner of the room, frightened: It's a lunatic!
     I started  looking at the papers the psychiatrists had  written, and it
looked pretty serious! The first guy wrote: Thinks people talk about him.
     Thinks people stare at him.
     Auditory hypnogogic hallucinations.
     Talks to self.
     Talks to deceased wife.
     Maternal aunt in mental institution.
     Very peculiar stare. (I knew what that  was -- that  was when  I  said,
"And this is medicine?")
     The  second  psychiatrist  was obviously  more important,  because  his
scribble was harder to read. His notes said things like "auditory hypnogogic
hallucinations confirmed."  ("Hypnogogic"  means you get  them  while you're
falling asleep.)
     He wrote  a lot of other technical-sounding  notes,  and I looked  them
over, and they looked  pretty  bad. I figured I'd have to  get  all of  this
straightened out with the army somehow.
     At the end of the whole  physical  examination  there's an army officer
who decides  whether you're  in or  you're  out.  For  instance,  if there's
something the  matter with  your  hearing, he has  to decide if it's serious
enough to keep you  out of the army. And because the  army was scraping  the
bottom of the barrel for  new recruits,  this officer  wasn't  going to take
anything from anybody. He was tough as nails. For instance, the fellow ahead
of me had two  bones sticking out  from the back of his neck -- some kind of
displaced vertebra, or something -- and this army officer had to get up from
his desk and feel them -- he had to make sure they were real!
     I  figure  this  is  the  place  I'll get  this  whole misunderstanding
straightened out. When it's my  turn, I hand  my  papers to the officer, and
I'm  ready to explain everything, but the officer doesn't look  up. He  sees
the "D" next to "Psychiatric,"  immediately reaches for the rejection stamp,
doesn't ask me any questions, doesn't say anything; he just stamps my papers
"REJECTED," and hands me my 4-F paper, still looking at his desk.
     So I went  out and got on  the  bus  for Schenectady,  and  while I was
riding on the bus I thought  about the crazy thing that had happened,  and I
started to laugh -- out loud --  and I said to myself,  "My God! If they saw
me now, they would be sure!"
     When I finally got back to Schenectady I went in to see Harts Bethe. He
was sitting  behind his desk, and he  said to me in  a  joking voice, "Well,
Dick, did you pass?"
     I made a long face and shook my head slowly. "No."
     Then he suddenly felt terrible, thinking that they had  discovered some
serious  medical  problem with me, so he said in  a concerned voice, "What's
the matter, Dick?"
     I touched my finger to my forehead.
     He said, "No!"
     "Yes!"
     He cried, "No-o-o-o-o-o-o!!!" and he laughed  so hard that  the roof of
the General Electric Company nearly came off.
     I  told the story to  many other people,  and everybody laughed, with a
few exceptions.
     When I got back to New  York, my father, mother,  and sister called for
me at the airport, and on the way home in the car I told them all the story.
At the end of it my mother said, "Well, what should we do, Mel?"
     My father said, "Don't be ridiculous, Lucille. It's absurd!"
     So that was that, but my sister told me later that when we got home and
they  were alone,  my father said, "Now,  Lucille, you  shouldn't have  said
anything in front of him. Now what should we do?"
     By  that  time  my  mother  had  sobered up,  and she said,  "Don't  be
ridiculous, Mel!"
     One  other  person  was bothered by the  story.  It  was at a  Physical
Society meeting dinner, and Professor Slater, my old professor at MIT, said,
"Hey, Feynman! Tell us that story about the draft I heard."
     I told the whole story  to all these physicists -- I didn't know any of
them except Slater -- and  they were all laughing throughout, but at the end
one guy said, "Well, maybe the psychiatrist had something in mind."
     I said resolutely, "And what profession are you, sir?"  Of course, that
was  a  dumb question,  because  we were  all physicists  at a  professional
meeting. But I was surprised that a physicist would say something like that.
     He said, "Well, uh, I'm really not supposed to be here,  but I  came as
the guest  of  my brother, who's a physicist. I'm a psychiatrist."  I smoked
him right out!
     After a while I  began to  worry. Here's a guy who's been deferred  all
during the war because  he's working on  the  bomb, and the draft board gets
letters saying he's important,  and now he gets a "D" in "Psychiatric" -- it
turns out he's a nut! Obviously he isn't a nut; he's  just trying to make us
believe he's a nut -- we'll get him!
     The situation didn't look good to me, so I had to find a way out. After
a few days, I  figured  out a solution. I wrote a letter to the draft  board
that went something like this:

     Dear Sirs:
     I  do not  think  I should  be  drafted  because I am  teaching science
students, and it is partly in the strength of our future scientists that the
national  welfare lies.  Nevertheless,  you  may  decide  that  I  should be
deferred  because of the result of  my medical report,  namely,  that  I  am
psychiatrically  unfit. I feel that no weight whatsoever should be  attached
to this report because I consider it to be a gross error.
     I am  calling this error to  your attention because I am  insane enough
not to wish to take advantage of it.
     Sincerely,
     R. P. Feynman

     Result: "Deferred. 4F. Medical Reasons."
Archdave's Feynman Pages - Part 3

"Surely You're Joking, Mr. Feynman!"

by Richard P. Feynman

by Richard P. Feynman
