so in general relativity if i take my self as a reference point, when i move forward does the whole universe go backward?
like is the reference point stationary ?
if so then is the force my leg exert enough to move the universe backward?
so in general relativity if i take my self as a reference point, when i move forward does the whole universe go backward?
like is the reference point stationary ?
if so then is the force my leg exert enough to move the universe backward?
Comments
that is the whole point of a reference point.
Lets pick an easier example. and some variation of this shows up in college physics classes.
your friend is standing on a moving train car. You are watching your with a camera and TV setup.
If the reference frame is locked to your friend, when your friend walks around, they stay in the center of the TV screen and everything else moves around. This would look like someone walking around with their hand out while facetiming you.
If the reference frame is locked to the train car, when your friend gets up and walks around, they will eventually walk out of view of the camera. Like if someone had walked offstage in a TV show.
Essentially, yes. The point of relativity is that any point can be named as the “stationary” point with equal validity, and so it’s arbitrary to pick any particular point.
That said, the math is a lot easier if you pick your reference points with care. No more valid, just easier. You can do the math that says your foot pushed the whole universe backwards when you took a step, but that’s a lot of very complicated math that you don’t have time to do.
It’s much easier to just say that the ground is the reference point here, and your foot pushed your body forward, and the rest of the universe isn’t really involved in this problem.