Taming time travel

New work solves paradoxes by making the impossible impossible

Novelists and screenwriters know that time travel can be accomplished in all sorts of ways: a supercharged DeLorean, Hermione’s small watch and, most recently, a spacetime-bending hot tub have allowed fictional heroes to jump between past and future.

Clockwise from top right: NATAQ/ISTOCKPHOTO; RADEKK/ISTOCKPHOTO;JNSOO1/FLICKR

Physicists have proposed several ways of getting around the grandfather paradox (shown).