Relativity explained

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Albert Einstein (1879–1955) is of course most famous for the massive contribution he made to physics with his theory of general relativity. He was a huge celebrity in his lifetime, and so had to spend a great deal of time trying to explain it to people.

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The story goes that at a party in America, a woman asked him to explain it in simple terms that she could understand. He told her this story:

A blind man and his friend are walking down a dusty road in hot weather.

“Oh, for a nice drink of milk,” said his friend.

“Drink I know,” said the blind man, “but what is this milk you speak of?”

“A white liquid”

“Liquid I know, but what is white?”

“White is the colour of a swan’s feathers.”

“Feathers I know, but what is a swan?”

“A bird with a crooked neck.”

“Neck I know, but what is crooked?”

His friend took hold of the blind man’s arm and stretched it out. “That is straight,” he said, then, bending the arm at the elbow said, “and this is crooked.”

“Ah!” said the blind man, “now I understand what milk is.”

The story

In his lifetime, Einstein was more than just a great physicist, he was also a major celebrity, feted everywhere in the way that movie or music stars are nowadays. Everyone in the western world knew he was a genius, but of course few understood relativity. This social, as well as academic, status would have a profound influence on world history when, after several scientists failed to persuade Washington of the danger of Germany developing an atomic bomb, Einstein (along with Leo Szilárd) wrote a letter to President Roosevelt. The government finally took notice; Einstein’s letter would lead directly to America’s decision to develop the bomb.

Because Einstein was such a public figure, there’s a huge fund of stories about his wit. The story above is pretty well known. (I was reminded of it when re-reading The Long Weekend by Robert Graves and Alan Hodge, a social history of Britain between the wars. If you’re interested in this period and have never read it, try to get hold of a copy. It’s a wonderful chatty, thoughtful and amusing read.)

There’s also a huge fund of stories about people’s inability to understand relativity. Dr Chaim Weizmann (1874–1952), himself a chemist and later Israel’s first president, once travelled with Einstein. “Throughout the voyage,” Weizmann told an interviewer when their ship docked in New York, “the learned professor kept talking to me about his theories of relativity.”

“And what was your opinion about them?”

“It seems to me,” said Weizmann, “that Professor Einstein understands them very well …”

If you’d like to understand Einstein’s theory of relativity try www.wimp.com/relativitytheory/

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