From phone boxes and flux capacitors to black holes and hot tubs, sci-fi has created plenty of ways to explore the fourth ...

Add Yahoo as a preferred source to see more of our stories on Google. Solutions to Einstein's famous equations back in the 20th century describe 'wormholes,' or tunnels through space-time. Mark ...

Gravity has become an unlikely viral villain, blamed for an imagined global blackout in which the planet briefly lets go of everything that is not nailed down. At the same time, some of the most ...