I understand what gravity is-it's a force that pulls together matter. But every website I've looked at, trying to find what MAKES gravity, just tells me what gravity is or has useless facts about gravity that doesn't answer my question. And no, there's not any particular reason why I want to know what makes gravity, but my dad didn't know (and no matter what he says, I'm pretty sure he knows everything about science. Everything important, anyways.) and I was just kinda curious. Atoms, too. What makes atoms and gravity?
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This is one of those "chameleon questions" -- looked at from one angle, it seems utterly stupid. Looked at from another, it is central and critical to the development of theoretical physics, and the cleverest, most probing, heart-of-the-matter question that could be asked.
The great Sir Isaac Newton, creator of modern physics, and discoverer of the first physical field theory -- that of universal gravitation -- refused to speculate on what gravitation "actually" is: "hypotheses non fingo."
Fast forward to Albert Einstein, who refined the basis of physics (Special Relativity -- SR, in 1905), and then realized that universal gravitation would need a theoretical overhaul, because now it violated the SR prohibition against instantaneous action at a distance. This led him to develop General Relativity -- GR, in 1915 -- in which mass-energy causes spacetime to curve, which in turn tells matter how to move. This in itself still doesn't tell us anything about what gravity "actually" is, except that it all boils down to geometry. The geometry of spacetime. The idea, once his approach to gravitation was taken, becomes: anything that the geometry of spacetime, and the various vector and tensor and spinor objects of that geometry can be responsible for, within the rules that govern them, will be a possible physical phenomenon. From this point of view, gravitation is the intrinsic curvature, in the form of the Einstein curvature tensor, G[µν], of spacetime, caused by the mass-energy-stress tensor, T[µν], according to Einstein's field equation:
The great Sir Isaac Newton, creator of modern physics, and discoverer of the first physical field theory -- that of universal gravitation -- refused to speculate on what gravitation "actually" is: "hypotheses non fingo."
Fast forward to Albert Einstein, who refined the basis of physics (Special Relativity -- SR, in 1905), and then realized that universal gravitation would need a theoretical overhaul, because now it violated the SR prohibition against instantaneous action at a distance. This led him to develop General Relativity -- GR, in 1915 -- in which mass-energy causes spacetime to curve, which in turn tells matter how to move. This in itself still doesn't tell us anything about what gravity "actually" is, except that it all boils down to geometry. The geometry of spacetime. The idea, once his approach to gravitation was taken, becomes: anything that the geometry of spacetime, and the various vector and tensor and spinor objects of that geometry can be responsible for, within the rules that govern them, will be a possible physical phenomenon. From this point of view, gravitation is the intrinsic curvature, in the form of the Einstein curvature tensor, G[µν], of spacetime, caused by the mass-energy-stress tensor, T[µν], according to Einstein's field equation:
keywords: gravity,What,creates,What creates gravity