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The Learning Kingdom's Cool Fact of the Day for March 29, 1999
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What are the fastest matter particles in the universe?
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The fastest known matter particles are ultra-high energy cosmic rays.
These are mostly atomic nuclei of various elements, which come zipping
down into the Earth's atmosphere at nearly the speed of light.
Cosmic ray energies are measured in electron volts. One electron volt
is the amount of energy that an electron gains when it moves across an
electric field of one volt. The fastest cosmic rays can carry more
than 100,000,000,000,000,000,000 (one hundred quintillion) electron
volts of energy.
How much energy is that? Pick up a rock about the size of your fist,
and throw it as hard as you can. This gives the rock roughly the same
energy as a single cosmic ray particle
When such a super-particle crashes into the atmosphere, it explodes
into an "air shower" of thousands of less energetic particles. The
air shower can be detected from the ground by the faint light it
emits.
Introduction to cosmic rays:
http://helios.gsfc.nasa.gov/cosmic.html
More about ultra-high energy cosmic rays:
http://www.sciam.com/0197issue/0197swordy.html
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