Crazy Eddie wrote:
There ARE several holes in GR. A dizzying number of them, in fact. I'm not speaking hypothetically here, I've been told by astrophysicists specifically that drawing any attention to the problems of General Relativity is an implicitly bad career move in some labs and especially in universities.
General Relativity, like Special Relativity, is extremely well-tested and understood. Eddington's experiments, modern GPS satellites... they've all confirmed GR's predictions and we've seen plenty of evidence from astronomical observations too.
Quantum gravity is another matter, where there are plenty of holes and ideas, but cosmological GR is generally pretty much regarded as a success.