Physicist's credentials

I apologise for the lateness of my response to Helmut Rechenberg's review of my book Hitler's Uranium Club (THES, January 26). I wish to comment only on the last paragraph. "Bernstein criticises and ridicules more careful and consistent treatments of the German uranium project (including Thomas Powers' account in Heisenberg's War.) What is rather absurd is his own war against great scientists whose procedure and arguments he cannot follow. This book puzzles the reader and harms the reputation of the editor. It should not have been written and certainly should not have been published."

My first publication on the subject of the transcripts made of the German nuclear scientists' recorded conversation in the summer and autumn of 1945 appeared in the August 13, 1992 edition of the New York Review of Books. I produced an annotated version of a portion of these transcripts. Because of the response I decided to do a book on the entire set of transcripts. It took nearly four years to complete. The reason for the delay was that I, with the help of colleagues, made an enormous effort to complete the historical picture. It took months, for example, to identify people whose names had been garbled by the translators. I was also interested in adumbrating the physics. I had more of a background in nuclear weapons than I discussed in the book. I had been at Los Alamos in the summer of 1957 and had gone to the test site in Nevada and had witnessed two Hiroshima-size above-ground tests. I had watched the assembly of hydrogen bomb parts and had talked extensively to the Los Alamos weapons people. During the following three years I was a consultant for the RAND corporation and, with several others, co-authored a report on the effects of upper atmosphere testing of hydrogen bombs. I worked with Freeman Dyson at the General Atomics Company on the design of a spaceship that was to be powered by a series of nuclear explosive charges. During this period I had clearance which entitled me to receive information on nuclear weapons. None the less, when it came to the technical issues raised by these transcripts I felt that I needed help. So I consulted a number of physicists. In particularly, I would like to single out Robert Serber whose Los Alamos "Primer" taught a generation of Allied scientists about nuclear weapons. Serber and I went over such things as Heisenberg's technical lectures line by line trying to understand what he had in mind and why he was so often wrong. All of this is reflected in my book and that is why I find Rechenberg's characterisation of it deeply offensive.

JEREMY BERNSTEIN Aspen Center for Physics, Colorado