In an article in the Daily Mail this week, British cosmologist Stephen Hawking outlined not one, but three, theoretically realistic ideas for traveling through time, one of which he says is even practical.

The Fourth Dimension

First, though, you have to get your head around the notion that time is a dimension, just like width, height and length.

Hawking uses the example of driving in your car: You go forward. That's one direction. You turn left or right, that's a second. You journey up a mountain road, that's a third. The fourth dimension is time.

"Time travel movies often feature a vast, energy-hungry machine. The machine creates a path through the fourth dimension, a tunnel through time. A time traveler, a brave, perhaps foolhardy individual, prepared for who knows what, steps into the time tunnel and emerges who knows when. The concept may be far-fetched, and the reality may be very different from this, but the idea itself is not so crazy," Hawking writes.

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