Tachyon
This is a purely hypothetical particle. It was first theorized in a 1967 paper, but its existence has never been proven. According to the theory, it always travels faster than light.
The word comes from the Greek “tachy” which means “swift.” It’s the same root from which we get “tachycardia,” which is a fast heartbeat.
Why I Looked It Up
I just keep seeing the word in science fiction settings. It has a futuristic sound to it, so it gets inserted in all sorts of books, movies, and shows.
I looked it up to find out if it was a real thing, or just a science fiction invention.
Sure enough, the Wikipedia page has an entire page for Tachyons in Fiction.
In general, tachyons are a standby mechanism upon which many science fiction authors rely to establish faster-than-light communication, with or without reference to causality issues, as well as a means to achieve faster-than-light travel. Science writer Sidney Perkowitz commented “that the very word “tachyon,” because of its unusual Greek-origin spelling and engagingly catchy hard “ch” sound, lends a certain “science-ness” or “science coolness to fiction.” Starting in the 1970s, tachyons were used in science-fiction to present a seemingly-plausible explanation for time travel and communication through time.