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Paper Black Holes

September 1, 2014

A scientific paper that was published 75 years ago doesn’t sound like much to get excited about. It was called “On Continued Gravitational Contraction.” Yet its conclusions were remarkable. It said that when a heavy star uses up the nuclear fuel in its core, gravity would squeeze it to an infinitely small point. To put it in more modern terms, the star would form a black hole.

The paper was written by J. Robert Oppenheimer, a physicist at the University of California, and a graduate student, Hartland Snyder.

At the time, scientists were just beginning to understand the process that powers stars, known as nuclear fusion. This process releases a lot of energy, which produces an outward pressure that prevents a star’s core from collapsing.

When fusion stops, though, there’s no more pressure to hold the core up, so gravity squashes it. Earlier studies had found that the cores of stars up to a few times the mass of the Sun would form ultra-dense “corpses” known as white dwarfs.

Oppenheimer and Snyder looked at what would happen to the heaviest stars of all. They found that once fusion shut down, gravity would cause the star to collapse to an infinitely dense point, and the star would vanish from sight.

The researchers couldn’t follow up on their work, though, because World War II intervened. Oppenheimer joined the war effort, and led the project that developed the first atomic bombs.

More about astronomy and World War II tomorrow.


Script by Damond Benningfield, Copyright 2014

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