Actually, this is about Joe's remarks on general relativity. Joe Bauman wrote:
But some great discoveries in science were made theoretically before there was evidence for the theory. The most obvious case is Einstein's general relativity, which was proved after it was published. The first proof was through observing the deflection of starlight during a total eclipse in 1919 -- I think that was 13 years after general relativity was published. If we didn't have a moon, we could not have checked the theory at that time.
This ignores the deviation in the Newtonian prediction for the precession for the perihelion of Mercury. This deviation had astronomers searching for a long for an "undetected planet" Vulcan, much like deviations in the orbit of Uranus led to predictions of the orbit for Neptune, and putative deviations in Neptune's orbit led to the finding of Pluto. Did not the Mercury orbital evidence provide confirmation before the eclipse? Was it not included in the original general relativity publication? On the other hand, gravitational waves still await discovery (if indeed they exist as predicted by Einstein). Interestingly enough, a few years after I had studied general relativity in college, I recall reading an article (in Science News, perhaps) that stated that the rotation rate of the Sun differed from Einstein's understanding, and that the new data worsened the fit of GR's prediction to the observe precession rate. I thought in the subsequent (lo, many) years I've never heard another peep on this subject, though I've been on the lookup for a followup. Jim