90th Anniversary Issue: 1940s
The Atomic Age, elementary finds and other highlights, 1940–49
By Science News
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Mushroom clouds usher in atomic age
Less than three years separated the first self-sustaining nuclear chain reaction on December 2, 1942, and the production and use of the first nuclear bombs against Hiroshima and Nagasaki (above). In 1946, weapons tests at Bikini Atoll — some witnessed by embedded Science News Letter reporters (7/13/46, p. 22; 8/3/46, p. 67; 8/10/46, p. 84) — brought home the field-acquired details of long-lasting mutation risks. At the end of the decade President Truman announced, “We have evidence that within recent weeks an atomic explosion occurred in the U.S.S.R.,” launching what would come to be known as the nuclear arms race. The president offered no details, but Science News Letter explained how such surreptitious weapons tests could have been identified and authenticated (10/1/49, p. 211). — Janet Raloff