Volume 22, Number 1 January 1993
ReviewsThe Manhattan Project: A Documentary Introduction to the Atomic Age
Michael B. Stoff, Jonathan F. Fanton, and R. Hal Williams, editors. Temple University Press, Philadelphia, 1991.
As superpower tensions decrease, the era of nuclear confrontation is ending. Nuclear weapons continue to abound, though, and it is impossible to imagine a world without them. The early days of the atomic era are vitally relevant history. The Manhattan Project gives us in one place many of the critical documents that bring this history to life.
Here is a photocopy of Einstein's famous letter to President Roosevelt and some of the correspondence that led to the Manhattan Project. In a 1943 telegram from FDR to "Former Naval Person" (FDR's name for Winston Churchill), he asks Churchill to get Britain involved with the "Tube Alloy" project. On 26 October 1943 FDR reports that he has personally intervened to stop an effort at unionizing the RadLab at UC.
The debates on targeting are powerful. On 12 April 1945 FDR died. Harry Truman soon learned of the Manhattan Project. We can read minutes of targeting meetings and see the kinds of considerations that entered the discussions. The Franck Report (11 June 1945) recommends against using the bomb against people and shows clear awareness of the importance of nuclear weapons for long-range national policy. These recommendations from scientists stand in stark contrast with those of political and military figures, who were conclusively influenced by casualty data from the war in the Pacific and from the Normandy invasion.
It is fascinating to read these formerly classified documents and to try to imagine being there, as mortals struggled with superhuman issues. It is humanizing to find typos in a memo signed by FDR. Does this sort of thing still happen in our world of spell-checkers? [Editor's note: Yes!] The awkwardness of language somehow helps to capture the mood when Secretary of War Henry Stimson wrote a memorandum to President Truman on 11 September 1945: "I think it [the bomb] really caps the climax of the race between man's growing technical power for destructiveness and his psychological power of self-control and group control--his moral power."
The Manhattan Project is a superb complement to Richard Rhodes' The Making of the Atomic Bomb (Simon and Schuster, 1986). The Manhattan Project gives us the documents themselves. They add a lot!
The Los Alamos Primer
"The Los Alamos Primer and the Frisch-Peierls memorandum of early 1940 [reprinted in this volume] carry a greater freight of historic import than perhaps any document in the history of technology." So writes Richard Rhodes in his introduction to this definitive, extensively annotated reprint of the five bomb-physics lectures given in April 1943 by Robert Serber for new arrivals at Los Alamos.
The Primer opens bluntly: "The object of the project is to produce a practical military weapon in the form of a bomb in which the energy is released by a fast neutron chain in one or more of the materials known to show nuclear fission." The "Primer" has long been an underground classic. Though declassified in 1965, it has not been widely available. This edition is an essential part of the library of anyone interested in Manhattan Project history. It is far more than a reprint. The original was typed; the new edition is typeset, with extensive comments by Serber interspersed.
Oppenheimer made it clear at the outset that within the closed Los Alamos community communications would be open. Serber's goal was to get the new arrivals up to speed fast. With time at a premium, the lectures had to be brief. Edward Condon took notes, which were discussed with Serber and made rapidly available to the community. Serber's "back of the envelope" calculations remain invaluable for teaching bomb and bomb effect physics. What better way to explain why Fat Man and Little Boy looked so different than with the original lectures on gun-type and implosion-type critical mass assembly.
Some of Serber's comments, such as his explanation of exponential notation, are educational and designed to help the naive reader. Others are comparisons of Primer numbers with current values. An example is the number of neutrons produced per fission andthe fission cross sections for U-235 and Pu-239. Both were way off, but compensating errors caused the quantities of interest, which involved product terms, to be quite accurate. Some of the notation is unique. An equation on the first page reads:
"1 kg of 25 = 20,000 tons of TNT"
Serber explains that U-235 was known as "25," U-238 was "28," and Pu-239 was "49." The 4 comes from the atomic number 94 and the 9 from 239. The word "plutonium" was unknown at LosAlamos in those days.
The primer uses the verb form "to fish." Serber explains that "'to fish' didn't stick. Today we say 'to fission,' but we kept -- the pronunciation: it's 'fishin'', not 'fizj-un.'" [He doesn't explain why nuclear engineers so often say"nuc-ular"].
Serber's comments include lots of anecdotes about life in those glory days, including new ones about the many personalities who so influenced physics from then to now.
The Frisch-Peierls memorandum was the document that showed the British that a fission bomb might work. Soon after it reached Henry Tizard in March 1940, the British government told Franklin Roosevelt of the importance of the concept, which "catalyzed the decision" of FDR to fund the Manhattan Project.
"The Los Alamos Primer" is under 100 pages and a more exciting read than Sherlock Holmes!