graphics about black holes or planets’ influence on gravity, etc., always show these bodies “sitting” on a flat surface and then bending that surface below them. is this a literal representation – ie is there a definitive “down” direction that always dips under the objects’ mass? or does it happen in multiple directions somehow? (or am i misunderstanding something fundamental about this curving?)
In: Physics
There’s a hilarious XKCD comic on this exact issue. In short the “sunken rubber sheet” isn’t even necessarily GR, even plain Newtonian gravity can use this representation. The downward displacement represents a lower potential energy associated with the 2d position. The third, vertical, dimension doesn’t represent position of any kind.
https://xkcd.com/895/
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