Portal Reloaded, the phenomenal time travel fan game based on Portal 2, now has a co-op mode that enhances the Valve puzzle game even further.

Time travel is deterministic and locally free, a paper says —resolving an age-old paradox. This follows research observing ...

But the researchers said scientists are still far from being able to teleport a living being through a time-travel portal. “Experimentally, for me, I will tell you that it’s very, very far away.

Physics Bizarre portal-like ‘ring wormholes’ could let you time travel. A ring wormhole is one that you could simply step through, like a portal through space – but new, more detailed models ...

They're on sale until March 6, so you've got loads of time. Paying almost nothing for Portal 2 makes Valve's excellent puzzler quite the deal, ... and a third green, time-travel portal as well.

The NBC sci-fi series La Brea has blown its mystery box wide open in Season 2, revealing more of what caused that mysterious time travel sink hole and just how deep (sorry) the conspiracy might reach.