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.
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.
The laws of physics actually accommodate the notion of time travel, through portals known as wormholes.
“The truth is wormholes are all around us, only they’re too small to see. They occur in nooks and crannies in space and time,” Hawking writes. “Nothing is flat or solid. If you look closely enough at anything you’ll find holes and wrinkles in it. It’s a basic physical principle, and it even applies to time. Even something as smooth as a pool ball has tiny crevices, wrinkles and voids.
“Down at the smallest of scales, smaller even than molecules, smaller than atoms, we get to a place called the quantum foam. This is where wormholes exist. Tiny tunnels or shortcuts through space and time constantly form, disappear, and reform within this quantum world. And they actually link two separate places and two different times.”
The tunnels, unfortunately, are far too small for people to pass through — just a billion-trillion-trillionths of a centimeter — but physicists believe it may be possible to catch a wormhole and make it big enough for people, or spaceships, to enter, Hawking writes.
“Theoretically, a time tunnel or wormhole could do even more than take us to other planets. If both ends were in the same place, and separated by time instead of distance, a ship could fly in and come out still near Earth, but in the distant past. Maybe dinosaurs would witness the ship coming in for a landing,” Hawking writes.