Why Mass Causes Space To Bend

[balboa]

Please answer with simplicity and great detail

[jim360]

You can have simplicity or great detail, but not really both.

Actually, you might struggle to get either, because -- well, I at least don't know how to answer the question "Why?". I can talk in some detail about "how", as much or as little as you want. But "why" is a question to which Science often doesn't provide an answer beyond "because it just does".

That rambling aside, matter causes Space to bend because instead of Space being in some sense just an "absence of stuff", you can think of it as being a bit more like a supporting framework in which everything lives and moves. Then when matter moves around in that framework you can perhaps see that you would expect there to be some interactions between the two. I move here, but the framework has to bend around a bit to "let me through". In this picture, the larger or more massive you are then the more bending space has to do in order to support your size and weight.

I think that's probably the best basic answer I can come up with for now. Matter causes space to bend because you can think of space (actually, space and time together) as a thing in its own right. But it's a picture that suffers from a number of technical flaws, such as what the framework is made of, and a few others that are a lot more subtle but you would be able to see once you had studied the subject in greater detail.

The main point I'd stress is that General Relativity is about describing what shapes the bending takes, rather than describing what causes it in the first place. The origin of the theory lies essentially in the claim that "physics is Universal" and then trying to extend this into the case where there is gravity as well. Perhaps that's the answer to the question: "because if mass didn't cause space to bend then physics wouldn't be Universal". Also, of course, because this theory works in experiment.

[Zacs-Master]

Why?