In a story from a few years back, Tim Harford outlines how a British Air Ministry prize for developing a “death ray” to use against enemy aircraft eventually helped kick off the discovery of radar:
The Chain Home radar tower in Great Baddow Chelmsford.
Photo by Stuart166axe via Wikimedia Commons.
… sometimes inventions need other inventions to unlock their full potential.
For the aviation industry, that story starts with the invention of the death ray, or at least an attempt to design a death ray, back in 1935.
Officials in the British Air Ministry were worried about falling behind Nazi Germany in the technological arms race.
The death ray idea intrigued them: they had been offering a £1,000 prize for anyone who could zap a sheep at a hundred paces. So far, nobody had claimed it.
But should they fund more active research? Was a death ray even possible?
Unofficially, they sounded out Robert Watson Watt, of the Radio Research Station.
And he posed an abstract maths question to his colleague Skip Wilkins.
“Suppose, just suppose,” said Watson Watt to Wilkins, “that you had eight pints of water, 1km [3,000ft] above the ground.
“And suppose that water was at 98F [37C], and you wanted to heat it to 105F.
“How much radio frequency power would you require, from a distance of 5km?”
Skip Wilkins was no fool.
He knew that eight pints was the amount of blood in an adult human, 98F was normal body temperature and 105F was warm enough to kill you, or at least make you pass out, which — if you’re behind the controls of an aeroplane — amounts to much the same thing.
So Wilkins and Watson Watt understood each other, and they quickly agreed the death ray was hopeless: it would take too much power.
But they also saw an opportunity.
Clearly, the ministry had some cash to spend on research. Perhaps Watson Watt and Wilkins could propose some alternative way for them to spend it?
Wilkins pondered. It might be possible, he suggested, to transmit radio waves and detect — from the echoes — the location of oncoming aircraft long before they could be seen.
Watson Watt dashed off a memo to the Air Ministry’s newly formed Committee for the Scientific Survey of Air Defence. Would they be interested in pursuing such an idea? They would indeed.
What Skip Wilkins was describing became known as radar.
