On his book of the elegant universe when he was explaining the warping of spacetime he use an analogy of a toy called tornado. Basically a spinning machine like a merry go round.(adsbygoogle = window.adsbygoogle || []).push({});

Anyway he said, let's give one ruler to the slim who is at the wall of the tornado,to measure the circumference, and other ruler to the jim who is at the center of the tornado, to measure the radius, and we observe the situation from above. Then he says slim will measure the circumference shorter than normal due to the fact that he puts the ruler along the direction of the movement and basic lorentz contraction effect kicks in. He says he had to put the ruler more, to measure the circumference and he will measure a longer circumference than we see from above. On the other side jim will measure the radius exactly the same value as we see from above. Because he puts the ruler vertical to the moving direction. So from these two measurement greene conclude that such measurement can not happen in a flat space surface, the space must be warped.

So my questions are:

1. First of all can we derive, at least roughly, that acceleration warps space from special relativity? We just use lorentz contraction and conclude the warping of space due to accelaration in the analogy.

2. How come Slim's ruler contracts but the circumference doesn't?

3. Jim is also moving relative to the outside observer, so isn't there any contraction effect occurs for him as well?

Thank you...

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# B Brian Greenes' Tornado Analogy

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