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Relativity Works!

Relativity Works!

By Anne Pawsey

It just goes to show that perseverance pays off. Over 90 years since Einstein published his theory of general relativity and 50 since an experiment was proposed to test two of its effects, direct evidence has been found to confirm that the effects do indeed exist.

Scientists have known gravity exists for ages but they were a bit hazy on exactly why it’s there; general relativity is the current favourite solution.

General relativity predicts that large masses (like the earth) distort the fabric of space time, a bit like a ball dropped on a trampoline. It’s this distortion that is responsible for gravity.

A marble placed on the trampoline rolls towards the large ball just as masses are attracted by gravity. This works fine with trampolines where you can see the curve but it’s a little harder to see with the earth. Instead of a marble on a sheet they used a gyroscope (a complicated spinning top) in a satellite orbiting the earth to observe the effect and they are confident that they have found it. The idea is simple, place the gyroscope in a satellite, line it up with a star and then see how much it changes direction over the course of a year. So all you need is a star, a telescope, and a spinning top - simple right?

That must be what
Stanford Professors Leonard Schiff, William Fairbank and Robert Cannon thought back in 1959. Unfortunately it was a bit more complicated than that. After four decades and the combined efforts of 94 post-grads, hundreds of undergrads and a large team of researchers, the project has finally produced some results which confirm one of the two predictions.

The second prediction - the earth dragging space-time with it as it orbits the sun - is very difficult to see. We’ll have to wait another eight months for those results.

So what made it so difficult? The problems were numerous; for a start, most of the components had to be invented by the team. You can’t buy a gyroscope at B&Q and once they’d made one that worked it had to be kept very, very cold (-270C) so they had to design something to put it in. Then they needed to be able to see how fast it was going without slowing it down. And these were just the obvious problems.

It’s a miracle it ever got off the ground let alone produced any results.

Learn more about the wonders of science at Anne's page.

If you liked this, you might also enjoy:
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- Spoof - How many scientists does it take to change a light bulb?

- Straight - Roger Highfield on writing Einstein's biog, and other stuff

- Strange - An altogether different theory

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23 May 2010
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