We're here today to talk about time travel.

A perennial, dare I say timeless, topic of science fiction, but is it possible?

Is there any chance at all that it could actually happen?

No, no, no, no, no, no, no, well, okay, kind of, not really, I'm Lee Billings.

I'm Clara Moskowitz, and this is Cosmos Quickly, the bi-weekly space podcast from

Scientific American.

We're going to have a little friendly debate.

Really, Clara? I came for a throwdown.

Well, a wrangle, a parlay, a confab.

Lee, what do you have against time travel?

So I love the idea of time travel, and in fact, I do it all the time.

Like most everyone else, I'm traveling into the future at one second per second.

Unless of a fan, though, of more speculative time travel, which is good fodder for goofy

sci-fi stories, but in the real world, it's an implausible distraction.

But really, we can stay within plausible physics and still see how more extreme versions

of time travel are possible. See, Einstein's special theory of relativity

shows that the rate time flows at depends on how fast you're moving.

Einstein strikes again. What a rascal.

If you're traveling in a starship at close to the speed of light,

you'll still experience the familiar one second per second taking of a clock.

But an observer back on Earth would see your clock moving

lazily slow.

...