The history of thermonuclear research traces its roots back to the year 1941. in a lecture delivered in May 1941, Tokutaro Hagiwara, a physicist at the University of Kyoto, postulated that a thermonuclear fusion reaction between hydrogen atoms could be triggered by the explosive fission chain reaction of uranium‐235. in September 1941, Enrico Fermi at Columbia University proposed a similar idea to Edward Teller. Discussions between Fermi and Teller ultimately suggested the feasibility of using an atomic explosion to initiate thermonuclear reactions in a deuterium medium. the conversations with Fermi sparked in Teller a decade‐long messianic obsession with the notion of building a thermonuclear superbomb.

H. F. York, The Advisors: Oppenheimer, Teller, and the Superbomb, W. H. Freeman, San Francisco (1976), p. 77.
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