A negative measurement of duration has added a new level of strangeness. In the car analogy, Tony Soprano is spending less ...

that time travel is possible but that time travelers would be restricted in what they did, to stop them creating a paradox. In this model, time travelers have the freedom to do whatever they want ...

This is a paradox, an inconsistency that often leads people to think that time travel cannot occur in our universe. [L]ogically it's hard to accept because that would affect our freedom to make ...

Hear Sagan via RealAudio Sagan: The grandfather paradox is a very simple, science-fiction-based apparent inconsistency at the very heart of the idea of time travel into the past. It's very simply ...

New data from the Atacama Cosmology Telescope has allowed astronomers to travel back in time to the dawn of the universe.

Einstein’s general relativity predicts the existence of closed timelike curves—space-time loops allowing theoretical travel back to past events. In a rotating universe, space-time could warp ...

Anderson's time-travel mystery, 'The Expert of Subtle Revisions,' explores the way history is affected by how it is told and who does the telling.