Radar

Radar_antenna

1935

It’s funny to think that the radar, one of today’s most useful inventions, was born out of a British-funded ‘death ray’ project during the runup to WWII. But that is exactly what the British government asked Scottish scientist Robert Watson-Watt to build: a machine to ‘destroy personnel’. Watson-Watt realised the death ray was impossible to build, but did suggest that radio waves could be used to monitor distant objects.