- #1
xcourrier
- 20
- 0
So, I feel like I have a pretty good grasp of Special Relativity, but GR is a whole different beast. I am really stuck on where the acceleration comes from for Gravity. For instance, it's easy for me to understand how an orbit can form from bent space (an analogy for the way I think of it is a car driving straight down the middle of a road, a sort of geodesic, in a circular race track). But if that object were to halt its orbit, it would then begin to fall or accelerate, and that part gets me. I feel like it has to do with the bending of time part, but its not very clear. For that matter, if we are accelerating through curved space time by standing on the surface of the earth, where does the space time we just accelerated through go?
I hear a lot of analogies, like the bowling ball and the trampoline (which happens to be all I get when I try to look anything up), but that always requires real life gravity pulling down on the demo to accelerate objects towards the center. I also hear the phrase "Space-time tells mass how to move, mass tells space-time how to bend," which doesn't seem inherently a relativistic idea, since you could easily replace "space-time" with "the force of gravity" and "bend" with "pull" and get "Gravity tells mass how to move, mass tells gravity which way to pull," which seems like a perfectly Newtonian view of the same thing.
I apologize if that was too many questions, it was really only meant to be one tackled a few different ways. If its easier to direct me to somewhere else, I would appreciate that as well. I learned Special Relativity from the World Science U site, but they don't have a section for GR yet. Thanks.
I hear a lot of analogies, like the bowling ball and the trampoline (which happens to be all I get when I try to look anything up), but that always requires real life gravity pulling down on the demo to accelerate objects towards the center. I also hear the phrase "Space-time tells mass how to move, mass tells space-time how to bend," which doesn't seem inherently a relativistic idea, since you could easily replace "space-time" with "the force of gravity" and "bend" with "pull" and get "Gravity tells mass how to move, mass tells gravity which way to pull," which seems like a perfectly Newtonian view of the same thing.
I apologize if that was too many questions, it was really only meant to be one tackled a few different ways. If its easier to direct me to somewhere else, I would appreciate that as well. I learned Special Relativity from the World Science U site, but they don't have a section for GR yet. Thanks.