It takes a brave man to reject a scientific paper by Albert Einstein. But that's what the physicist Howard Percy Robertson did in 1936, as editor of the journal Physical Review. Einstein was so enraged that he never published there again.

If Einstein were alive today, he might thank Robertson, who saved the great scientist from retracting the most far-reaching prediction of his theory of relativity — the existence of gravitational waves. The first direct detection of Einstein's waves was announced last week to much fanfare and celebration. Scientists say the waves emanated from the powerful collision of two black holes.

The finding was hailed as a vindication, though Einstein was one of the biggest doubters of his own idea. He flip-flopped several times over the years, said physicist Daniel Kennefick, co-author of "An Einstein Encyclopedia." The tale ended well, thanks to Einstein's wisdom in knowing when to be sure, when to have doubts, when to ignore his doubters and when to listen to them and regroup.