<< As Einstein said, "theory
tells us what we can observe." >>
A true Einstein joke. The famous test of general relativity theory was in, I think, 1919, when people went to see whether the predicted "bend" in light from the sun via Mercury could be observed in a set of fortutious circumstances. It was observed, and Einstein was vindicated. Some reporter asked him, weren't you worried that it might not turn out as you expected? Oh no, said Einstein. Then I should be sorry for the dear Lord. The theory is correct.
--jks