Emma Unson Rotor took leave from her job as a math teacher in the Philippines to study physics at Johns Hopkins University in 1941. Her plans were disrupted when the Imperial Japanese Army invaded and occupied the Philippines. Unable to access her Philippine government scholarship to attend Johns Hopkins, she joined the Ordnance Development Division at the National Bureau of Standards. It was here that she did groundbreaking research on the proximity fuze, the “world’s first ‘smart’ weapon,” in the words of physicist Frank Belknap Baldwin, who also helped develop the technology.

This Best Of episode, which first aired in December 2923, is also available in a Spanish adaptation, narrated by Laura Gómez.