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Q & A: does the Earth stand still?

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Most recent answer: 03/01/2016
Q:
BH If the real way we've proved that the speed of light is constant, was with the experiments like Michelson-Morley Experiment, why can't we come to the conclusion that the earth is really standing still?. I know it sounds silly, but seriously, leaving emotions aside, can't it be that the earth is standing still, while the whole universe is spinning around it? Of course, we have the Pendulum Experiment that suggests that the earth is moving, but could some other factors be effecting the Pendulum? Maybe like Suns or moons gravity?Thanks so much for the answer, in advance.
- Aron (age 35)
Rochester
A:

Nice question. As Einstein and Infeld pointed out, General Relativity does let you construct a coordinate system in which the Earth is stationary. Then to get the Foucault pendulum result, and innumerable other effects, you need a to add a weird twisty gravitational field. The problem is that that field wouldn't come from  the Sun or anything else. It has no source. It would just be an ugly complication to the description of spacetime. SO for most purposes we avoid picking frames like that one.

Mike W.


(published on 03/01/2016)

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