"Where's the ka-boom?" The history of Plutonium

In Michael Frayn’s play Copenhagen, the Danish physicist Neils Bohr  and his German colleague Werner Heisenberg discuss, among many other topics, the critical mass of uranium, that is the amount needed to produce a chain reaction for an atomic bomb. Heisenberg shows Bohr his figures proving an impossible amount of uranium was needed, making an atomic bomb unfeasible. Bohr points out a misplaced decimal point in his work, which distorted the answer by at least a factor of ten. Heisenberg is shocked and so are we: if Heisenberg had got his sums right, he might have persisted in the work and Hitler got an atomic bomb before the Americans.

In Jeremy Bernstein’s book Plutonium: A history of the world’s most dangerous element, there is an even more interesting possibility. The great Italian physicist Enrico Fermi actually achieved nuclear fission in 1934 but either did not see it or did not realize what he was looking at. The official discovery of nuclear fission did not happen until 1938. By 1945, the US had working atomic bombs. Consider those dates. If Fermi had recognized fission in 1934, the arms race may have started then, and World War Two been an atomic war from day one.

Such is the role of chance in world history. And in science.  It is worth remembering that scientists are like the rest of us. Despite best practice and best intentions, they can still make mistakes, see only what they want to see, or not see what they are not looking for. Uncertainly is an integral part of science and should not be used as an excuse to dismiss it.

This book is a history of the discovery and development of plutonium, which is a great element for making bombs, but not much else.  I enjoy the occasional book about science though I don’t always, if ever, entirely understand them. Accepting this means I can enjoy these books for what I can understand rather than worry about what I do not.

Bernstein makes this story intelligible for the non-scientist, even allowing them to skip most of the most technical chapter. He does his best to explain some complex ideas in chemistry and physics and does pretty well. He is not helped however by a serious misprint. After he explains the traditional notation as “the atomic number at the lower right and the atomic mass at the upper left”, the equation for the first observed and noted example of nuclear fission is printed thus: ₉₂U^238  -> ₅₆BA¹³⁷ + X. I have trouble telling my left from my right. I have even more trouble remembering the difference between atomic mass and atomic number and how they affect the behaviour of elements in reactions. Imagine the time I spent trying to understand that passage. I hope this is rectified in any future editions.

One reason I find these books difficult is that I have trouble understanding how scientists work at the levels at which they do. Physicists and chemists worked on plutonium for some years, finding important properties and behaviour, before they managed to create enough to see it – and then only through a microscope. The scale of the work bamboozles.

But this is not just a book about chemistry and physics. The human factor, as I alluded to above, plays an enormous part. The scientist who first identified nuclear fission, Otto Hahn, noted what he saw but could not work out what had happened. His former colleague, Lise Meitner, now in another country due to Austria’s Nazi race laws, was the one who identified the process and the results correctly. But the Nobel Prize was awarded to Hahn on his own, ignoring the work of his female colleague both before and after his discovery. For his part, Hahn couldn’t see the problem with that.

Hahn meanwhile discovered he had won the prize while in a British prison after the war, where he was held with other scientists who had been working for the Nazis. It’s good to see that the Prize Committee, however imperfectly it works, could recognize achievement free of political considerations. If only they could always do that. Ah well, they are humans as well.

Bernstein ends the book with a consideration of the amount of plutonium in the world now, most if not all contained in warheads on the end of missiles. What are we to do with it? How do we live with this dangerous leftover from the Cold War? Which I suppose raises in however tangentially a manner the question of nuclear power, and should we look to nuclear power as a stepping stone on the way to a world less dependent on fossil fuels. To me, this is a no-brainer: of course we should. If people look beyond scare-mongering and sloganeering to science and technology, they would discover a safe, reliable, green form of electrical power, which we can use while we develop renewable energy sources to the point where they are both practical and affordable. Forget Chernobyl or the Simpson's Monty Burns; focus, for example, on the the 80% of power France gets from nuclear stations, and has done for decades. Phew, didn't meant to get all political, but there it is.

And here is a shameless plug: I won this book in a Facebook competition run by Australian popular science magazine Cosmos. If you like science, do check them out. I’ve also won a Nicolas Cage DVD called ‘Knowing’. I’ve yet to watch it but I’ll let you know how it goes.