Curvy space in and around massive objects [closed]

Question

If space curves around massive objects, what happens to the space within the massive objects?

Answer 1

Space doesn't curve around a massive body the way a dirt road curves around a lake. It doesn't avoid it.

When you heat a metal ruler it's gets bigger. So you might think your objects got smaller. But if all your rulers had always been that big you wouldn't notice.

But if your rulers got bigger or smaller the farther you got from a massive body, then the surface area of a shell $4\pi R^2$ (as measured by rulers on the surface) might not compare to the volume $4\pi R^3/3$ you expect to be inside the spherical shell (as measured by rulers positioned throughout the space inside).

Now we can correct for metal rulers getting bigger or smaller (by using lasers, or rulers made of different metals that expand differently so you can correct for it). However, if there is something about space itself that affects how measurements with rulers turn out, then we can't correct for it, and that just means the measurements happen similarly as if space was curved.

Now clocks can tick in a way where the number of ticks you gets depends on your path, just like the ruler readings depended on where they were. So it's not just space that is curved but spacetime.

But there is no evidence of anything other than spacetime and a metric field (that tells rulers and clocks what to do).

Answer 2

The curving itself indicates something is residing. Means for a massive body to reside in space, the space has to be curved, it can not accommodate a massive body (or equivalent energy) without curving. Therefore, as the massive body moves, the curving moves with it. Space does not curve just around the body, it curves even inside it. The curving is not necessarily geometrical. However, the math works just fine considering curving as geometrical.

So, the massive body resides in space, and also curves it.