Q: In the spring of 1950 a serious effort gets underway to develop the
hydrogen bomb. And Stanislaw Ulam begins a set of calculations. Tell me about
RR: It had always been a clear necessity with the hydrogen bomb to calculate on
paper (simulate, we'd say now, the progress of the explosion, the blooming of
the explosion, what's called the hydrodynamics of the explosion), because if
you didn't have a kind of a paper version of what was going to happen, and you
tested a design and it was a dud, you wouldn't know whether it was wrong
because your design was wrong or whether it was wrong because there was no way
to make this happen anyway. So they had to simulate it on paper.
[Edward] Teller, in `47, had written a report saying, "We should delay working
on the hydrogen bomb"-- Notice this in the context of his later saying, "Los
Alamos kept us from building it." He said, "We should delay working on
the hydrogen bomb until such a time as the digital computer" (as it was called
in those days) "has been developed to the point where we can do this
So when Ulam, after Truman announced the crash program to build the hydrogen
bomb, sat down to do the calculation by hand, he was simply trying to get
moving. It wasn't only that he wanted to see whether Teller was right or not.
Of course, he needed to know that. That's what the calculation was for. But
he thought, "Well, let's see what we can do by hand." So he sat there throwing
dice (another one of those literary moments in--in the development of this
weapon), throwing dice to get random numbers so that he could run what's called
a Monte Carlo calculation...
And the farther Ulam worked the numbers, the more it was clear that this
wasn't going to work, that the heat would radiate off the device faster than it
could heat itself up.
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