The prediction of black holes.
¥The black holes predicted by Schwarzschild were so
heavy that event light could not escape (this is why they are called black
holes).
¥Einstein did not accept this prediction. He and Arthur Eddington, a British
astro-physicist, stated that "they did not like the smell of black
holes".
¥The controversy did not get a lot of attention since
Einstein and Eddington were considered the experts on general relativity.