Is gravity matter? Is gravity energy?

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If it's neither, what is it?

This.
[youtube]http://www.youtube.com/watch?v=yhG_ArxmwRM&list=UUZYTClx2T1of7BRZ86-8fow&index=9&feature=plcp[/youtube]

Oh, so it's a force. It's not matter or energy, but a force.

*Nods* It's a force, one of the fundamental forces.

Mass warps the curvature of space and time - this causes the effect known as gravity. It is not an energy, but a curvature of space-time. This is called the geodetic effect or geodetic warping.

It is a force because it effects the behaviour of mass and even massless particles such as photons. But there is no energy involved, since it does so not by exerting any energy, but changing the geometry of space-time.

The weight of nothingness crushing down on what is?

Its interesting that forces, electric etc keep stuff apart, what if nothingness is pushing it together?

What if fusion is like the merger of two bubbles and electric or strong force is like the surface tension attempting to prevent the collapse?

Actually, warped space-time does contain energy. There is a quantity in general relativity called the "stress-energy tensor" that is directly affected by gravitational curvature.

That's one of the weird things about gravity: a gravitational field is produced by energy (mass = energy), and the energy of that field itself also gravitates. In situations where that runs away you end up with a singularity/black hole.

Gravitation is curvature of the space-time manifold. It is not a force.

ruveyn

It was my understanding that no one really knows what gravity really, truly is.

That is, we have a pretty good picture of what gravity is from a special relativity standpoint, and we have a pretty good picture from a quantum mechanical standpoint, but we can't get the two models to agree on much of anything. And this is somehow the reason we have string theories, which are unprovable.

Of course my understanding of physics ends somewhere just past the speed of light being constant in all frames, space and time being the same thing, mass and energy being the same thing, and that those conclusions all somehow derive from each other.

And don't get me started on Dark Matter. So, really big astronomical objects seem to have more mass than they have. OK, back it up a second. Clearly they're not just counting up stars to come up with how much mass these giant bodies appear to have, right? Clearly there is a good reason they didn't just say, "well, obviously our metrics for counting baryonic matter are off, and since it's so far away there's probably more baryonic matter there than we can accurately account for", rather than invent a whole new type of matter to explain it, right? I mean, there's like zero chance that someone's going to go, "Oh, duh, there was this bunch of asteroids over here that we forgot to count! Well what do you expect, it's so damn dark in space!" RIGHT? So there has to be a simple explanation as to why we are so confident of this. How are we so sure that really big astronomical objects have more mass than can be accounted for with baryonic matter, short of flying in there and counting all the baryons?

One hypothesis is that elementary particles called "gravitons" are responsible for the gravity interaction

Could empty space just not be empty, but be what is responsible for gravity? Could this explain momentum? Could dark matter be everywhere evenly distributed but weak in interaction. This would explain why they can not detect a graviton. It is a system of weak interactions some how less pressure exists in the space between two masses and not that mass attracts at all?

Well..It does seem to me that "dark energy" is being invoked to explain something that Einstein may have already explained a long time ago.

Dark energy is invoked to explain why the shrapnel(ie galaxies) from the cosmic handgrenade (the whole universe) that went off when the Big Bang happened is not only not slowing down but is speeding up.

Why is matter moving faster?

Its seems to me that that would be logical outcome of relativeity wihout any exotic dark energy.

If all of the matter in the universe were placed together around one point (the condition that supposedly existed at the time of the big bang) it would all turn into one big massive black hole because of the infinitite warping of space.

But when the big bang happened the energy of the explosion was great enough to overcome the gravitiation exterted by all of that matter (to put it newtonian terms), or to overcome the warping of space (to put it in einsteinian terms). And the shrapnel (ie galaxies) were able to hurl outwardly away from the ground zero of the big bang at great speed.

And that hurtling continues to this day.

So all of the matter in the Universe continuse to become less and less concentrated . Thus the agregate warping of space by matter continues to get less and less. So space flattens out and expands -taking the matter with it.



So - there is no energy (dark or otherwise) is being expended to speed up the galaxies. They are just moving with their same original momentum from the big bang. Its this unwarping of space thats causing increased distances (and thus doppler shifts) which give the appearance that galaxies are pushing a gas pedal..

Its just the logical result of space ittself expanding as the already spreading mass of matter irons out the original big warp in space.