Building the H Bomb: A Personal History

By Kenneth W. Ford, 2015, 221 pages, World Scientific, Hackensack, NJ, ISBN: 978-9814632072, $47 hardback, $17 paperback

The invention of hydrogen bombs was a major, page-changing event. An increase by a factor of one thousand (ten doublings) from kilotons to megatons is a big deal. Suchan increase in prowess can easily overwhelm arms control efforts to constrain the beast. Ken Ford lived these events as a Princeton graduate student, doing his pure physics thesis in parallel with his calculations of fission-fusion-fission for the 10.4-megaton Mike test of 1 November 1952. Ford’s historical treatment of nuclear events is timely since we do not have solid plans for stronger nuclear controls in 2016, only principles and hand wringing. It is my hope this book will force us to go to the well, once more, to seek a solution beyond "deterrence seems to work."

Let’s place Ford’s book in context. Richard Rhodes’ book Dark Sun: The Making of the Hydrogen Bomb is an excellent historical document by a historian.1 Ford’s book, written by a physics–insider, makes a significant contribution to the history of the science, as well as to the history of the political conflicts around the H-Bomb program. Ford combines excellent descriptions of the nuclear learning process, along with humorous and illuminating discussions about the designer physicists. He does a nice comparison/contrast on the nuclear rivals, Stan Ulam and Edward Teller, concluding that they both were a bit on the lazy side, with Ulam too laid–back and Teller too tense.2

Ken Ford entered the H bomb workforce in June 1950 for two years as part of the Matterhorn Project at Princeton and Los Alamos under Professor John Wheeler. This was a time of uncertainty for the H-bomb, as the "classic superbomb," having a boosted primary to ignite a deuterium secondary had been shown to fail by Stan Ulam and Cornelius Everett. Ford was a member of the Matterhorn Project in February 1951 when Stan Ulam showed that the radiation–implosion mechanism could raise temperatures and pressures sufficiently to fission nuclear deuterium. Ford then used desk calculators and IBM cards to show definitively that the Mike's deuterium fusion would propagate and succeed when its Teller-Ulam radiation pressures were taken into account.

The basic physics is straightforward:

  • A ten-kiloton primary exploded over 100 nanoseconds has an average power of 4 x 1020 watts.
  • The radiant flux developed over a 10 cm radius primary sphere is 0.3 x 1022 W/m2.
  • The black body temperature to develop this flux is 15 million kelvin.
  • The average x-rays from this black body have an energy of 6 keV and a wavelength of 0.5 micron.
  • Radiation channels direct the x-rays perpendicularly to the secondary surface, which evaporates, carrying momentum and compressing the secondary inward.

As it turns out Teller didn’t believe this was true until Ulam reported his results to him. They co-authored Los Alamos Manuscript (LAMS) 1225 on 9 March 1951. The issue of what to do with H bombs got sidetracked as Teller over-reached for credit as part of his lobbying to create a second weapons’ lab at Livermore. Ford concludes (pg. 23): "As to Teller, I have to conclude that, despite his later testimony about his thinking in December and January, his ideas about radiation implosion and the equilibrium Super had not gelled prior to his February meeting with Ulam." Teller avoided mentioning the Ulam connection in his book "The Legacy of Hiroshima." Ford knew both Ulam and Teller well as he calculated yields for the various designs. Ford followed these events as a participant and as a thorough student of historical documents. Bethe has also written on these events,3 stating the following: "In January 1951, Teller obviously did not know how to save the thermo nuclear program" (p. 14).

Ford discusses the divisive history of the H–bomb project. On 30 October 1949, the General Advisory Committee of the Atomic Energy Commission advised to proceed with building high-yield boosted uranium weapon and to cease building H–bombs. The GAC decision was based on moral grounds and because there was no clear path to the H–bomb at that time. Once it became clear that H–bombs could be built, moral dissuasion disappeared. Teller was greatly disturbed by the GAC decision, which contributed to his over-reach to exclude credit from Stan Ulam.

Over the years it has been my pleasure to deal with Ken Ford when he was chair of the Forum on Physics and Society in 1981 and during 1987–93 when he directed the American Institute of Physics. I did not know of Ford’s 1950’s involvement with the H-bomb until I read his book. The Epilogue of his book spells out his personal response to weapons’ work over the decades. He knew that the factor of 1000 increase in yield was going to be a major problem for our planet, and concluded that he would no longer participate in these matters. In 1968, at a public meeting in Cloudcroft, New Mexico, Ford stated in a calm way that he would no longer work on nuclear weapons. The public statement was given, not to gather press attention, but to preclude a future change of his mind. I am glad that Ken Ford wrote Building the H Bomb, to tell us some of the history and physics of H-bomb weapons, to tell us revealing stories of himself and other participants, and to tell us of his moving personal journey along this difficult path.

Prof. David Hafemeister (emeritus)
Physics Department, Cal Poly University


1 Richard Rhodes, Dark Sun: The Making of the Hydrogen Bomb, Simon and Schuster, 1995.

2 K. Ford, “Building the H–Bomb: The Big Idea,” APS News, pg. 8, June 2015.

3 Hans Bethe, “Memorandum on the History of the Thermonuclear Program,” LANL, May 28, 1952 (declassified), and “Comments on the History of the H-Bomb,” Los Alamos Science, pg. 43–53, Fall 1982.

These contributions have not been peer-refereed. They represent solely the view(s) of the author(s) and not necessarily the view of APS.