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The Making of the Atomic Bomb By: Richard Rhodes

In this book Richard Rhodes takes what some might consider dry history and gives it the life and flow of a novel. Instead of just throwing out names, opinions, and controversies involved with the growth of nuclear power he develops a connection between the reader and the figures involved. Approximately the first half of the book is focused on the cultures, background, and first encounters with nuclear physics of many big name scientists. So the reader is not only being given the knowledge of what happened but also a feeling, an understanding, of why events and emotions unfolded as they did.

The book opens with a first chapter dedicated almost entirely to the background of Leo Szilard from his college years to the early 1930's. Shortly after it steps backward into the last third of the 19th century to the battle over the existence and structure of the humble atom. Here Clerk Maxwell had just proposed the idea of the electromagnetic field and electromagnetic radiation, light being a form of it. This helping to crack the shell of a purely mechanical universe even though he himself remained a strict Newtonian.

On the few short pages following this Rhodes expresses Michael Polanyi's philosophy of science, evidence for which appears throughout the rest of the book. Polanyi was a chemist friend of Leo Szilard who later took up the study of science itself. He asked basic questions of science as Rhodes outlines in this quote from page 32, “How were scientists chosen? What oath of allegiance did they swear? Who guided their research-chose the problems to be studied, approved the experiments, judged the value of the results? In the last analysis, who decided what was scientifically “true”?.” As Rhodes explains, Polanyi came to the idea of science being an “open republic.” To start, Polanyi used an analogy of a group of workers completing a jigsaw puzzle. In a basic repetitive process, his example being shelling peas, each worker working independently can be an effective and efficient method organization since there is no building process. However a jigsaw puzzle, like science, has a linear progression, each new discovery building on the last. So in a pure independent situation having 100 workers is as effective as 1. Polyani's solution was to put all the workers in the same room in sight of each other so when one made an advancement everyone would be able to see and benefit from it. Here each worker would be able to work off of their own ingenuity but still benefit and progress the whole. The communication between everyone was the key to progress. So in this way scientists are able to work individually in specific fields that align with their skill while still being part of and progressing the whole of scientific knowledge by building on and with the work of others. Now this describes a way of organizing scientists but does not cover how they are chosen or their work approved. Polyani covers this angle with a trickle down system. Starting with one scientist making a discovery, the acceptance trickles down due to respect and testing. Scientists whose fields overlap that of the first's look at in and give their approval or disapproval. Then those farther separated base their opinions on trust and respect, filtering down the line.

Now I have extensively noted approximately 5 pages, but why? Because I think, and possibly Rhodes does too, that this is a present and imperative structure to science and is obvious in the development of nuclear physics. It was not all one person that made these advancements, it grew from the minds and work of dozens, maybe hundreds. Just naming the “big ones” the list goes on, Szilard, Rutherford, Fermi, Bohr, Thomson, Einstein, Chadwick, Oppenheimer, Currie, Meitner, Frisch, Neumann. All these scientists working together but alone. Finding and placing the elusive puzzle pieces then sharing the knowledge. And beforehand each of them having at one point to prove themselves, to prove their knowledge and skill, and earn the respect so that their discoveries and thoughts would be given a chance. This may be so visible in nuclear physics because of it's focused end point and the rush toward it, driven by wartime fever, the possibility and realization of the atomic bomb.

Among the tales of the lives of the nuclear scientists the idea of nuclear fission grows. Radioactivity was discovered, tested, and eventually understood. The transformation of elements by decay and bombardment was accepted. However for Otto Frisch and Lise Meitner there was puzzling outcome of neutron bombardments of uranium. The products they thought should have been radium isotopes oddly seemed to be those of barium. This didn't seem possible because there wasn't enough energy in a single bombardment to allow for the many simultaneous cases of alpha decay. They also knew that the atoms could not be being blown in half, as quoted “Nor was it possible that the uranium nucleus could have been cleaved right across. Indeed a nucleus was not like a brittle solid that could be cleaved or broken: Bohr had stressed that a nucleus was much more like a liquid drop.” While on a walk the two had a spark of inspiration. Atomic nuclei are held together by a strong nuclear force which is opposed by the weaker electrical repulsion of the positively charged protons. Frisch estimated that at the charge in the nucleus would have to be approximately 100 to cancel out the binding forces. Uranium with an atomic number of 92 is not far off from this threshold. From this the pair hypothesized that possibly, if the nucleus of a uranium atom was struck by a neutron of even minimal energy then it would oscillate. If by chance the nucleus elongated as part of it's oscillations then it was possible the electrical repulsions which have a longer effective range that strong nuclear forces could begin to win out and pinch off the nucleus. This pinching would then start to form two “droplets” being forced apart by the electric forces. Within each droplet the strong nuclear force would still prevail and eventually two separate smaller nuclei would be left after the original nucleus fully broke apart. For Frisch and Meitner these two were, barium and krypton, solving the puzzle of the mysterious products. Fission had been hypothesized, but the true foreshadowing of it's future came from the calculations the two made after. Each atomic fission should produce about 200 MeV of energy they determined. While this in itself is an insignificant amount of energy the fact that it came from a single atom made it unfathomable. For comparison Rhodes gives various figures, the energy of a powerful chemical reaction is only 5eV per atom, and the largest planned cyclotron at the time was only supposed to accelerate particles to 25MeV.

When news of Frisch and Meitner's discovery reached Szilard the next phase of nuclear physics began. Szilard recognized that if neutrons could cause the splitting of uranium and if enough neutrons are emitted by this breakdown then a chain reaction should be possible. In a letter to Lewis Strauss, Szilard noted what a possible chain reaction could lead to, “I see...possibilities in another direction. These might lead to large-scale production of energy and radioactive elements, unfortunately also perhaps to atomic bombs. This new discovery revives all the hopes and fears in this respect which I had in 1934 and 1935, and which I have as good as abandoned in the course of the last two years...." The fears were already recognized as the race to determine the neutron output began.

For a reaction to occur Szilard determined at least 2 neutrons must be ejected per fission. The day of truth came at the completion of an experiment run by Fermi and assisted by Walter Zinn and partially Szilard. The apparatus consisted of a radium capsule, nested in a beryllium cylinder, set inside of a cadmium lined box that was filled with uranium oxide. An ionization tube connected to an oscilloscope was inserted into the box and was shielded from the radium's radiation by a lead plug. Then using the oscilloscope the neutron flux produced by the uranium could be observed. The results came out as this, for every neutron captured about two neutrons were released. Chain reactions were possible.

From here the second half of the book dives into the story told in every documentary and classroom. World War II, the Manhattan Project, Oppenheimer, and Rhodes does an excellent job of telling this part of history. He definitely took great care in his research to provide an amazing depth to the events that occurred and the people behind them. However I am still most impressed by his lead up. There are documentaries, essays, textbooks, etc, that cover the development of the bomb but few ever take the step back to the beginning of nuclear physics presenting it's growth as well as that of the scientists and drove it forward. Rhodes took a massive amount of historical data and wrote it into a book that made it as interesting and moving as a novel without beleaguering the truth. He more than earned the Pulitzer Prize he received for his work on this book, __The Making of the Atomic Bomb__.