Black holes were born

In 1939 Albert Einstein wrote a technical article that argued against the possibility that a star can be contracted to a single point: particles making up the star would end up rotating at velocities that were too high. In the same year, Robert Oppenheimer, together with his student Hartland Snyder, drew an apparently exactly opposite conclusion: that when a sufficiently heavy star runs out of nuclear fuel, it will collapse into an infinitely dense point, closed off from the rest of the universe. Both Oppenheimer and Einstein would soon be preoccupied by choices of an altogether different nature; and, again, set out on a different course.