bacondota t1_j1jh59e wrote on December 24, 2022 at 9:19 PM

Reply to comment by mayonnace in Are people in the international space station experiencing time faster than us? by [deleted]

Speed of light is the speed of causality. And you are trying to separate Time from Space. It is not 'time' that is related to gravity, it is the 'SpaceTime fabric'. It is one thing

mayonnace t1_j1jo8ei wrote on December 24, 2022 at 10:12 PM

Does stretchedness of space also change depending on matter/energy/particles stuff, like time does? If so, then in which direction? If we have more particles accumulated in a point space-time, time seems to be streching up, how about space? Does it shrink? Bend? Enlarge? Do distances change? Or is it just that it takes more particles per volume unit, like its volume getting stretched up?

I guess I'm still thinking them separately, but if I can get the space perspective as I did with the time, perhaps I could try to blend them together easier.

t3hmau5 t1_j1ju2ts wrote on December 24, 2022 at 10:59 PM

Gravity is the result of matter warping spacetime.

Imagine setting a really heavy bowling ball on a trampoline. It will sink, stretching and curving the fabric of the trampoline that otherwise was flat, uncurved. If you were to roll a smaller ball straight past (but not at) the well created by the bowling ball, it will circle the well, gradually spiraling inwards as it loses energy. Analagous to one body orbiting another.

Matter does pretty much the same thing to spacetime, but its in all directions (since spacetime isn't a flat plane like the trampline). Non-euclidean geometry is the geometry of curved surfaces (put simply) and can shed insight on some of your more specific questions.

Edit: watch this Video

mayonnace t1_j1k32u1 wrote on December 25, 2022 at 12:13 AM

That's a fun video. Thanks!

I've seen the fabric metaphor before, but I'm still having difficulty on not separating time and space from each other. I think now I'm very close to understanding though.

I'm starting to think that space is not really a volume, and it's more of a relative thing. Like if right now we could get rid of the half of the matter in space, like draw a line and cut it into two pieces like a pie, and simple erase one side, then the new center of the space would be the center of mass of the remaining half. Or let's say, if there was only one particle in the whole universe, then there would be no space since it couldn't move relative to anything. It couldn't have speed. So, space is not actually an empty volume, if there aren't more particles that can move relative to each other. What do you think? It's not correct, right? Is it?