A theoretical type of subatomic particle that is supposed to move faster than light. For ordinary particles, the speed of light (a constant denoted as c) is the upper limit; for tachyons, c is the lower limit. According to relativity theory, such particles move backward in time; that is, their path and energy are determined by causal conditions in the future.

(FTL limerick: A young lady named Bright)

A company offering satellite based internet access via Service Partners to North American and European locations via small oval dishes. Future plans for more global coverage.

All traffic is back-hauled to the a large dish in San Diego and sent to the backbone via the San Diego Supercomputer Center network.

http://www.tachyon.net/

Gerald Feinberg postulated in 1967 that particles could move faster than light if their rest mass had an imaginary value. This would allow the mass-energy value of the particle to be a real value like everything else in the universe. He named these particles tachyons from the greek word for "swift".

Back in the real world, the only possible evidence of actual tachyons is the electron neutrino.

Source: Alternate View Column AV-61 in the October-1993 issue of Analog Science Fiction & Fact Magazine, written by John G. Cramer. See http://www.npl.washington.edu/AV/altvw61.html

The father of your humble narrator works in space science at the Applied Physics Laboratory of Johns Hopkins University. He likes to tell a story about a theoretical discussion he had with one of his coworkers some years back, about tachyons. Apparently the conversation ended when his friend sent him a message on the Lab's then-brand-new email system, something like this:

John,

Sorry to hear about that tachyon fiasco; hope it doesn't ruin your career. I told you it wouldn't pan out.

Steve

The message was post-dated by about three years. Geek humor at its finest.