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National Museum of Nuclear Science & History

Secrecy in the Manhattan Project

Grade Level:
Billboard at Oak Ridge


Students will read primary documents and debate on the value of secrecy versus the importance of open collaboration for the Manhattan Project.



  • Historic images emphasizing the need for secrecy
  • The article "Holes in the Security Fence" from The Manhattan Project anthology by Cynthia Kelly (pp. 264-265)
  • Excerpts from J. Robert Oppenheimer's November 1945 speech related to international collaboration and openness
  • Niels Bohr's 1950 open letter to the United Nations



The clash between the scientists and the military was primarily over the scientists' need for open collaboration versus the military's insistence on secrecy. This tension was felt most acutely in three contexts:

  1. While establishing laboratory and security procedures
  2. Whether scientists could petition the president to consider whether to drop the atomic bomb on Japan
  3. Whether atomic secrets should be shared after the war, as many scientists urged

Oppenheimer insisted on the need for collaboration between scientists to solve the complex scientific, engineering and technical issues of developing an atomic bomb. General Leslie Groves was adamant that the project had to protect the knowledge of the atomic bomb from falling into the wrong hands.



  • Divide the class into two groups, one representing the interests of the military and the other the scientists. Each side comes up with recommendations for the right balance of ensuring security and allowing for scientific collaboration from their point of view. Then the two sides must negotiate a common set of standards and procedures.
  • Compare these recommendations with the actual practices at Los Alamos. Which ones are more restrictive? Which ones might have been more effective in preventing espionage? What are some of the trade-offs between the need for controlling top-secret information and creating conditions for scientific innovation and productivity?