Reminiscences of Los Alamos 1943 1945
Lawrence Badash, Joseph O Hirschfelder, Herbert P Broida (editors)
Towards the end of 1938 German and Austrian scientists Otto Hahn, Fritz Strassman, Lise Meitner, and Otto Frisch showed that when a uranium nucleus is struck by a neutron, it may split into two smaller nuclei, an event Frisch called "nuclear fission". Frisch at the time was in Stockholm working with Niels Bohr. Within a few weeks Bohr made the result public at a meeting in Washington, DC. Even before the meeting's end, physicists were sneaking back to their labs to confirm it themselves.
They were excited because they immediately realized that nuclear fission would release HUGE amounts of energy. Most of them also quickly realized that a fission event was likely to release a few neutrons*, meaning that a self-sustaining chain reaction was possible -- imagine a pandemic, where every dying uranium nucleus infects three more. This was exciting! A brand new source of energy! With Hitler's ascension looming in Germany, Hungarian physicists Leo Szilard, Eugene Wigner, and Edward Teller, concerned about military applications, convinced Albert Einstein to write a letter directly to President Roosevelt warning him. Roosevelt took the threat seriously, and thus the Manhattan Project was born.
Over the course of the next few years physicists learned more about uranium fission, and the possibility of an enormously powerful bomb came into view. Everyone believed that Germany was working on a bomb, and that if they built one, Hitler would not hesitate to use it. Indeed, most of the world's best physicists were German. But Hitler was fast changing that. Because of the persecution of Jews, many scientists fled Europe for the USA. For instance, Italian physicist Enrico Fermi, whose wife was Jewish, used his receipt of the Nobel Prize as an excuse to flee Italy and came to the USA. Fermi, technically an enemy alien, built the world's first working nuclear reactor under the stands of the University of Chicago football field. (Incredible but true!) It went live on 2-Dec-1942.
Thus in 1943 the decision was made to get started on a bomb. The laboratory in which it would be built was created on the mesa at Los Alamos, New Mexico. (It is still there, and still in operation. Anyone can visit now -- I myself have been there -- but most of us are not allowed further than the small museum at the entrance.) The new director, a brilliant theoretical physicist named J. Robert Oppenheimer, moved in in early 1943. Over the course of the next two and a half years, the laboratory grew to a town housing 5000 people, and they built a bomb. The first nuclear explosion occurred in the Trinity Test near Alamogordo, New Mexico, on 16-July-1945. Days after that nuclear weapons were used for the first and only time (so far) in war at Hiroshima and Nagasaki, Japan.
Reminiscences of Los Alamos is not a history of the atomic bomb. (For that, I recommend the excellent and readable The Making of the Atomic Bomb by Richard Rhodes and the almost equally excellent biography American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer by Kai Bird.)
Instead, Reminiscences of Los Alamos is a book of primary source information for historians. Realizing that firsthand sources of information on Los Alamos were literally dying out, the editors of this book organized a series of lectures by people who had been at Los Alamos during the building of the bomb. The lectures took place in 1975 at the University of California at Santa Barbara. This book contains the lectures in written form. Each lecture was followed by a question and answer period, which are also reproduced here. There are ten lectures. Six are by physicists. All of these are men. Although the physicists at Los Alamos included a few women, almost all the scientists were men. There are also talks by three of the physicists' wives: Bernice Brode, Laura Fermi, and Elsie McMillan. The talks are, for the most part, not very technical.
The most entertaining talks are the ones by George Kistiakowsky and Richard Feynman. Feynman's talk is called "Los Alamos from below", because Feynman was very young, only a grad student when he joined the Manhattan Project. It was obvious to everyone (and to none more than Feynman himself) that he was a very smart guy. He eventually became one of the greatest physicists of the 20th century. Kistiakowsky was an explosives specialist. He believed that explosives could be used as precision tools -- a viewpoint that was critical in building the plutonium bombs exploded at Trinity and Nagaski.
The most interesting (as opposed to entertaining) talks are those by the three women. They do the best job of conveying the atmosphere and feel of Los Alamos. One of the remarkable things about the Manhattan Project was that, once you were in, you were in for the duration. No one who knew about the bomb being built could be allowed to work outside the Manhattan Project. One gets the feeling, however, that it was not difficult to keep the physicists' noses to the grindstone. Bernice Brode writes
They all seemed to be enjoying themselves as scientists always do when they ponder their problems together. No one has to drive them; they drive themselves when they have an intriguing problem. And so it was at Los Alamos. Even an outsider like myself, with no idea what the problem was, could feel the inner urge for scientific solution.
Laura Fermi says, in answer to a question
One interesting thing to me is that during the war I was at Los Alamos only a year and a half or even less, and still it seems such a big part of my life. I don't know if I can convey what I mean. It was so different, it was such intense living, that it seems impossible that in my case it actually lasted hardly eighteen months.
With a few exceptions, no one had any moral qualms about what they were doing. They believed they were in a race with Hitler's Germany that would determine whether civilization survived. Also, it is obvious that the scientists were caught up in the delight of doing science with all these Great Minds, as Brode pointed out. It was peak experience for almost everyone involved.
(As it happens, we now know that Germany never mounted a serious effort to develop nuclear power or weapons. Hitler was misled (possibly an intentional deception by Werner Heisenberg) to believe there was no realistic possibility there. The Japanese likewise had only a small program that made no real progress.)
As a reading experience, it is patchy. Many of the talks are dry and quite dull. If, however, you have ever experienced the excitement of doing world-class science, you will recognize the feeling.
*How did physicists immediately know these things? They knew how much energy each nucleus of the different sizes has. How they knew that is a complicated story, but it doesn't matter here. By 1938 they had tables of nuclear energies, and they knew that uranium nuclei have far more energy than an equal mass of smaller nuclei. So if a uranium nucleus splits, all that extra energy will be released somehow. Similarly, the uranium nucleus is 60% neutrons, while smaller nuclei are closer to 50%. So if a U nucleus breaks into two smaller ones, there will be extra neutrons that have to go somewhere.
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