Answering gravity with gravity?

[Hogbobson]

Hello, MMO-champion!

I have a feeling this is not the best place to ask such questions, but I believe in you! So let's have a go.

Einstein's general theory of relativity states that matter curves space and that this is in fact what is causing gravity, since things fall into this curvature.
To put it in perspective: Take an elastic piece of textile material, and put a ball on it: the material curves down, and any other ball placed close to this curve will roll into this.

So here's my question: What causes the curvature of space? I know matter is responsible for the curvature, but what causes is it in the first place? What makes the ball placed on the piece of textile make the curve? It certainly can't be more gravity, since this is what causes gravity. Like Newton said that gravity acts at a distance just ... because! I feel that matter causes the curvature of space just ... because! Does anybody have an answer? Or is this still outside our understanding of the world?

[Auloria]

The idea is that "gravity" isn't the Newtonian force but a result of the curvature. The ball on the sheet is a bad analogy because you know that in the real world gravity is pulling the ball down. However, the curvature is only due to the mass, but it just happens to look the same mathematically as the ball on the sheet.

I'll see if I can find a better picture on the webz.

[s_bushido]

I'm pretty sure scientists don't have all the answers about gravity, which is why they're working on unification.

edit: Your question is confusing. What causes the curvature of space? Gravity.

[StayTuned]

"What is gravity?" is like the biggest question in science so far, besides "what is the beginning of everything?"

There are theories, some are accepted, some more than others, some are ridiculously stupid.


Anway, MMO is actually a good place to come and ask about everything thats scientific. We have some really smart people here.

[Badpaladin]

According to Einstein, and greatly simplified, it's mass that causes the curvature we sometimes call gravity. I actually prefer thinking of putting a ball in a glass of water - the water has to flex around the ball to make it "fit", thus the ball changes the curvature of any linear path through the water from one end of the glass to another.

[Laize]

Hello, MMO-champion!

I have a feeling this is not the best place to ask such questions, but I believe in you! So let's have a go.

Einstein's general theory of relativity states that matter curves space and that this is in fact what is causing gravity, since things fall into this curvature.
To put it in perspective: Take an elastic piece of textile material, and put a ball on it: the material curves down, and any other ball placed close to this curve will roll into this.

So here's my question: What causes the curvature of space? I know matter is responsible for the curvature, but what causes is it in the first place? What makes the ball placed on the piece of textile make the curve? It certainly can't be more gravity, since this is what causes gravity. Like Newton said that gravity acts at a distance just ... because! I feel that matter causes the curvature of space just ... because! Does anybody have an answer? Or is this still outside our understanding of the world?

The curvature of spacetime is just what happens in the presence of mass.

Sort of like how my stomach gets queasy when I smell brussels sprouts.

[Deleted]

Not like I have anything better to comment.

[Netherspark]

As I understand it that analogy you put forth about the heavy ball and piece of textile is pretty much how it really works, just in 3 or more dimensions. Just as the ball 'warps' and distorts the cloth, so do planets, stars and all things warp and distort space.

The reason why is similar to displacement. Space is an object; if you put something inside it pushes everything else away to make room for it. But instead of pushing matter/mass away it pushes and warps the fabric of space-time.

[semaphore]

So here's my question: What causes the curvature of space? I know matter is responsible for the curvature, but what causes is it in the first place?

Why does the angles within a triangle nearly always add up to 180 degrees?

Like Newton said that gravity acts at a distance just ... because! I feel that matter causes the curvature of space just ... because! Does anybody have an answer? Or is this still outside our understanding of the world?

Yes, it's basically just because it does. As John Wheeler puts it: "matter tells Spacetime how to curve, and Spacetime tells matter how to move".

In other words, "matter tells matter how to move".
Expanding Space: the Root of all Evil?, Matthew J. Francis, Luke A. Barnes, J. Berian James, Geraint F. Lewis, Publications of the Astronomical Society of Australia 24(2) 95–102

[Prokne]

Matter causes gravity, the curvature of space is the field of gravity that is created. The steeper the curve, the stronger the gravity.

[Wikiy]

Things like electromagnetism (light, electricity, radiation, heat, etc.) have already been explained (as in, why and how they occur, not how they act on macroscopic levels, there are different theories for that) at the "nano"scopic level by quantum mechanics, as well as the weak and strong nuclear forces. The only force of the universe that remains to be explained by quantum mechanics is gravity. General relativity is just the theory and mechanism that explains how gravity acts.

So yeah, the point is, there's no sensible answer we here could ever give. It's one of the biggest problems (or mysteries, probably more appropriate) of science that's at the moment trying to be solved by theoretical physicists. It's what the "theory of everything" and the string theory that we hear about all the time try to explain.

[v2prwsmb45yhuq3wj23vpjk]

I think what he's saying is that the explanation given with the ball and curved spacetime doesn't really explain gravity, it just explains that space curves near massive objects. A curvature with things falling towards the center is a concept that is familiar because gravity pulls things down relative to Earth, and explaining that gravity works through curving space doesn't really explain it at all because it uses gravity in its explanation. Even the ball in water thing doesn't explain how gravity works. Both of those things just explain part of how gravity acts.

I just chalk it up to how things aren't explained very well in school. Like, I was taught that inertial planes are directly additive, but apparently they aren't.

[Wikiy]

I think what he's saying is that the explanation given with the ball and curved spacetime doesn't really explain gravity, it just explains that space curves near massive objects. A curvature with things falling towards the center is a concept that is familiar because gravity pulls things down relative to Earth, and explaining that gravity works through curving space doesn't really explain it at all because it uses gravity in its explanation. Even the ball in water thing doesn't explain how gravity works. Both of those things just explain part of how gravity acts.

Well, as I've said, we're stuck with the "how it looks like and what happens" at the moment. We need to wait a bit until the "how exactly does it happen" and "why does it happen".