Are Wormholes Tunnels for Time Travel?

Stefan Lovgren
for National Geographic News

September 16, 2005

As any self-respecting science fiction fan knows, wormholes—theoretical shortcuts through space and time—make for excellent time travel portals.

The latest movie to transport people into the past is this summer's A Sound of Thunder, based on the classic 1952 Ray Bradbury novella. In it, a group of hunters build a time machine, which looks like a wormhole of sorts, to travel back to the dinosaur era. There, things go awry when one hunter kills a butterfly, which completely changes the course of history.

The movie was widely panned by critics and seems to have quickly slipped out of theaters. But the questions it raises—the mystery of time and the possibilities of traveling through it—remain among the thorniest in physics, keeping a growing number of scientists occupied.

It's not like scientists are looking for a way to actually travel through time. But some believe that theorizing about how it could be done—maybe by using a wormhole in space—will help them understand and perhaps even revise the laws of physics.

"Traversable wormholes are extremely useful as gedanken experiments"—the term describes experiments that can be reasoned theoretically but are impractical to carry out—"to probe the limitations of general relativity," said Francisco Lobo, an astrophysicist at the University of Lisbon in Portugal.

http://news.nationalgeographic.com/news/2005/09/0916_050916_timetravel.html