According to Stephen Hawking, building a time machine isn't hard: "All you need is a wormhole, the Large Hadron Collider or a rocket that goes really, really fast." Just grab one of those and hop right through the fourth dimension.
In an article for the Daily Mail, Hawking discusses time travel and theoretical possibilities. It's a long read that'll make your head spin, but it's certain to leave you awed and perhaps a bit hopeful. [Daily Mail via MSNBC]