Time travel has long been a favorite idea in science fiction. Stories about changing the past or visiting the future have ...

A ring in space, at least on paper, can do something a black hole cannot. It can connect distant regions without forcing anything through crushing gravity or a singularity.

While most time travel movies ignore quantum physics, Christopher Nolan's Intersteller, Avengers: Endgame, Planet of the Apes ...

This month marks 40 years since Michael J. Fox, as Marty McFly, jumped into a souped-up DeLorean and went back in time, putting his very future existence at risk. (SOUNDBITE OF FILM, "BACK TO THE ...