Einstein did not believe, then or later, that these results actually corresponded to anything real. In 1939, for example, he produced a paper that provided, he said, “a clear understanding as to why these ‘Schwarzschild singularities’ do not exist in physical reality.” A few months later, however, J. Robert Oppenheimer and his student Hartland Snyder argued the opposite, predicting that stars could undergo a gravitational collapse.2
