Michalson and Morley proved that there were no interference patterns for beams going with each other, against each other or at 90 degrees to each other.
Earth orbit was chosen for the experiment because it was pretty darn handy, and everything else wasn't.
Once again, I'm just a cook, exploring the mysteries of physics.
/johnny
Basically it has to do with the conception that everything in the universe is in motion, ergo there is no ‘absolute reference frame’. That is to say, anytime we make a measurement of something the value we get is with respect to the contextual frame of reference we’re measuring from—i.e., we ourselves are also moving at some given rate of speed ourselves.
A straightforward example of this would be to think about what the speed of a car driving 55mph looks like from different reference frames. If you’re traveling alongside them at 60mph, then from your perspective they’re traveling -5mph relative to you. But from the perspective of a stationary (~relatively speaking!) person at the side of the road, that car is driving 55mph.
There are some caveats for the speed of light, however—see here for more: http://en.wikipedia.org/wiki/Special_relativity#Lack_of_an_absolute_reference_frame
Basically it has to do with the conception that everything in the universe is in motion, ergo there is no ‘absolute reference frame’. That is to say, anytime we make a measurement of something the value we get is with respect to the contextual frame of reference we’re measuring from—i.e., we’re also moving at some given rate of speed ourselves.
A straightforward example of this would be to think about what the speed of a car driving 55mph looks like from different reference frames. If you’re traveling alongside them at 60mph, then from your perspective they’re traveling -5mph relative to you. But from the perspective of a stationary (~relatively speaking!) person at the side of the road, that car is driving 55mph.
There are some caveats for the speed of light, however—see here for more: http://en.wikipedia.org/wiki/Special_relativity#Lack_of_an_absolute_reference_frame