Particle Accelerators

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Getting hit by a pitcher's best fastball would hurt. So would getting hit by the most powerful cosmic rays -- particles that zip through the universe at nearly the speed of light. Though they're smaller than an atom, the particles carry as big a punch as a fastball. And the "pitchers" for such particles may be supermassive black holes.

A black hole is an ultradense object with such powerful gravity that not even light can escape from it. Supermassive black holes are millions or billions of times heavier than the Sun, and inhabit the cores of most galaxies, including the Milky Way.

These black holes pull in gas from the space around them. The matter gets so hot that its atoms are ripped apart, leaving a "soup" of charged particles. Magnetic fields can shoot some of these particles into space at near lightspeed.

A recent study found that the black hole at the center of the Milky Way may shoot particles all over the place. When they ram into other particles around the black hole, they emit gamma rays -- perhaps accounting for a gamma-ray "glow" in the center of the galaxy.

Another study found that black holes that are more massive than the Milky Way's can boost particles to even higher energy levels, producing the most powerful cosmic rays. They can race across billions of light-years before they hit -- with the impact of a speeding fastball.

We'll have more about black holes tomorrow.

Script by Damond Benningfield, Copyright 2007

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