Cosmic rays actually do cause
bit rot. A study in the
80s by
IBM placed
RAM testers in
Boulder,
Colorado,
Leadville,
New York City, and
underground in
Kansas City. Boulder had 5 times more
errors than New York, and Leadville had ten times as many as New York. The
elevation of the towns has a lot to do with it, since Leadville doesn't have as much
atmosphere to absorb
sub-atomic particles at 10,152ft. Boulder is at about 5,000ft. New York is at
sea level. However, the shape of the
earth's
magnetic field has a lot to do with it, too.
la Paz has a similar
altitude to Leadville's, but is at a different
latitude.
The sub-atomic particles that make up cosmic rays knock electrons out of orbit, generating just enough voltage to send a gate into the wrong digital state.
The effects get worse with smaller components. Makers of modern microprocessors have to be very careful about terrestrial radiation, as well. If
their chip fab becomes radioactive, it will not turn out working chips.
All this stuff can be found in an IBM research journal somewhere. Specifically, the IBM Journal of Research and Development, Volume 40, Number 1.
So keep your smoke detector away from your chips!