If you've spent any time watching science fiction shows, you've probably heard of tachyon rays, a tachyon matrix, or just free-floating tachyons. Tachyons are particles that travel faster than light. And one professor finally came up with a use for them. Sort of.

Gregory Benford is many things: a professor of physics, a Nebula-Award-winning science fiction author, and the inventor - at least in theory - of the tachyonic antitelephone. The phone makes use of tachyons, tiny particles that move so fast that they go faster-than-light. How anyone will manage to round them up, let alone work them into a telephone is anyone's guess, but once it's here, the tachyonic antitelephone will be a very useful invention.

If you've ever forgotten to call someone, you know the pain of finally, belatedly, picking up the phone. A tachyonic antitelephone would allow you to phone someone back in time. Because tachyons go faster than the speed of light, they would travel back in time to before you ever made your phone call. It's tough to say if the tachyons would be programmable - whether they would always call forty-five minutes ago or whether they could be set for any time - but Benford thought of one conversation that would take place across the span of two hours. Or not.

Let us say that one person, Tasha, agrees to call the second person, Data, if she has not heard from him by twelve. She makes the call at twelve, and Data receives it. Data, wanting to correct his error, picks up the tachyonic antitelephone and calls back to eleven o'clock. Tasha receives the call, and has now heard from him by twelve, and so doesn't call him. This means he doesn't call her by twelve except he already has, unless he hasn't which means she's called him, which means he has called her. (That call would still be the thing that made the most sense about their relationship, though.) The point, Benford concluded, is that the conversation only takes place if it has never taken place.

My problem with the tachyonic antitelephone is more complicated. That telephone would mean that there would also be a tachyonic antiinternet, which means movie theaters will be pre-sold-out, and I could only order movie tickets before anyone knows there will be a movie scheduled, or even a movie at all. Eventually, I'll have to just guess which movies will be coming out, which means that right this minute I need to order A Good Day to Twi Hard, the Twilight-Die Hard crossover to be made in 2017. Don't pretend you wouldn't see it.

[Via The Universal Book of Mathematics, University of Oregon.]