Saturday, June 22, 2013

General Relativity

After reading what Conservapedia had to say about E=mc2, I got curious as to what they'd say about general relativity

The theory of relativity has been repeatedly contradicted by experiments [snip] 
It is unlikely tenure or a Ph.D would be awarded to any critic of the theory.
Well the second sentence is true, at least for physics departments.  But according to Wikipedia,
The predictions of general relativity have been confirmed in all observations and experiments to date. 
And if that's not enough for you, consider this: the GPS system has to apply a correction to it's atomic clocks.  These clocks run slower by 7 microseconds per day (because they're moving fast) and faster by 45 microseconds per day (because they're farther from the Earth's gravity).  So the   GPS clocks are tweaked to compensate - if they were on the ground, they'd run 38 microseconds per day slow. (45-7=38)

38 microseconds doesn't sound like much, but without the relativistic tweak, GPS positions would drift off by about 10 km per day.

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