This episode was first broadcast in July 2013.This year, Nature celebrates its 150th birthday. To mark this anniversary we’re rebroadcasting episodes from our PastCast series, highlighting key moments in the history of science.During the Second World War, scientists worked on secret projects such as the development of radar. Their efforts were hinted at in the pages of Nature but the details, of course, couldn't be published. In this episode, historian Jon Agar explains how war work gave physicists a new outlook and led to new branches of science. We also hear from the late John Westcott, whose wartime job was to design radar systems.From the archiveNature Volume 150 Issue 3794, 18 July 1942Sound effects courtesy of daveincamas, piet.candeel@pandora.be, guitarguy1985 and acclivity at freesound.org For information regarding your data privacy, visit acast.com/privacy