Editing 1940 in science (section)

==Physics==
* January 5 – [[FM radio]] demonstrated to the [[Federal Communications Commission|FCC]] for the first time.
* March – [[Frisch–Peierls memorandum]]: [[Otto Frisch]] and [[Rudolf Peierls]], at this time working at the [[University of Birmingham]] in England, calculate that an [[atomic bomb]] could be produced using very much less enriched [[uranium]] than has previously been supposed, making it a practical proposition.<ref>{{cite book|last=Gowing|first=Margaret|authorlink=Margaret Gowing|title=Britain and Atomic Energy, 1935–1945|year=1964|location=London|publisher=Macmillan Publishing|oclc=3195209|pages=40–43}}</ref>
* April 10 –  [[MAUD Committee]] first convened in Britain to consider the feasibility of an atomic bomb.
* [[Cavity magnetron]] invented by [[John Randall (physicist)|John Randall]] and [[Harry Boot]].
* [[Spontaneous fission]] first observed by [[Georgy Flyorov]] and [[Konstantin Petrzhak]].