I remember hearing a physicist on NPR saying that some people theorize that gravity was leaking into our universe from another dimension. I Googled it before writing this and found one link saying that some think the universal expansion is accelerating because gravity is leaking out of our universe into another dimension.
Modern science reportage has failed you, I'm afraid. Back in like 2005, George Dvali and others suggested "leaking into other dimensions*" as a possible reason for a weakening of gravity over very large distances, that could explain expansion.
Experiment since then stands against this notion. LIGO (the Laser Interferometer Gravitational-Wave Observatory) allows us to measure gravitational waves, so we can see if there's a loss over distance. There does not seem to be.
The very next link said there is no evidence for other dimensions. So who knows?
Folks have looked for various bits of evidence suggesting extra dimensions, and so far no evidence for them has been found.
And are Einstein's discoveries law or theory at this point?
Oh, goodness, how the education system has failed us.
In colloquial use, "theory" indicates a proposition that is highly questionable, not well tested.
In the world of hard sciences, "theory" does not have that connotation. Einstein's theories of Special and General Relativity are extremely well tested, and have passed every test so far put to them. "Law" is not a technical term in science - there is no well-defined place where we say, "this is physical law". "Law," instead, is descriptive. A physical law is a proposition that has held up to a lot of testing.
*This does not mean what a D&D player, science fiction author, or comic book reader would think it means.