[ExI] Relativity in Linearly Moving and Rotating Frames

[Damien Broderick]

At 09:50 PM 9/28/2008 -0700, Lee wrote:

>>once you grasp that the Earth is rotating once a day, how obvious 
>>is it which body is orbiting the other?
>
>One is supposed to be able to shut oneself up in a laboratory
>and confirm whether or not one is in an accelerated frame.
>(Foucault  pendulum

Yes, but I don't happen to have one about my person. Nobody does. We 
"know" naively that the sun spins around the earth because we *see* 
the bloody thing moving while *we're* plainly not moving. Which has 
nothing at all to do with which one orbits the other, but gave almost 
all humans the overwhelming impression that it does. Now, when we 
break free of that motionless flat earth illusion, but before we set 
up huge slow pendulums, I'm not sure it's all that obvious that the 
earth orbits the sun. I mean, the planets cavort back and forth, so 
they're special cases, break out the epicycles, Jim, but both sun and 
moon plod along in much the same way, yet we're meant to intuit that 
one orbits earth and the other doesn't. (Well, one's bright all the 
time and the other waxes and wanes, which is a clue--but what if we 
orbited Jupiter instead? Gets tricky, neh?) I suspect most of us 
non-scientists "know" the true answer only because we've been told 
repeatedly since childhood.

Damien Broderick