“Then the Time Traveller put forth his finger towards the lever. ‘No,’ he said suddenly. ‘Lend me your hand.’ And turning to the Psychologist, he took that individual’s hand in his own and told him to put out his forefinger. So that it was the Psychologist himself who sent forth the model Time Machine on its interminable voyage. We all saw the lever turn. I am absolutely certain there was no trickery. There was a breath of wind, and the lamp flame jumped. One of the candles on the mantel was blown out, and the little machine suddenly swung round, became indistinct, was seen as a ghost for a second perhaps, as an eddy of faintly glittering brass and ivory; and it was gone – vanished! Save for the lamp the table was bare.” -H.G. Wells’ The Time Machine
H.G.Wells was responsible for our first iconic “time machine” – he even coined the phrase – basically a high-tech chair rigged with a dial and a level. Though time travel had been talked about before, Wells’ book certainly romanticized the idea. Since, we’ve seen it again and again: Time jumpers altering their pasts, spinning off into the future, even shredding to Chuck Berry at the high school hop. The novelty of time travel has morphed into a frequent sci-fi trope, and is a regular on prime-time TV and in best-selling romance novels.
When Hot Tub Time Machine hit theaters Friday, it came packed with plenty of goof, but gave us little explanation of the time traveling tub. Picture this: Just your average group of guys, vacationing together, getting all silly-faced in a hot tub until somebody spills a Russian energy drink named after the largest nuclear accident of all time and well, things just start to get weird. (Read Steve’s review here: Hot Tub Guilt Complex: Was I the Only One Who Got Bored?)
Thing is, there’s never been much of a consensus as far as time travel is concerned, except that it involves a boat load of physics we don’t quite understand (yet). There isn’t much concrete direction in Hollywood as far as the how-to of time travel is concerned, so we asked physicist Dr. Michio Kaku, host of the Science Channel’s Sci Fi Science: Physics of the Impossible, for some solid direction.
Allie Townsend: So first off, is any of this possible?
Michio Kaku: Well, there is a loophole in Einstein’s equation that even Einstein realized was there. In Einstein’s equation, time is a river. It speeds up, meanders, and slows down. The new wrinkle, is that it can have whirlpools and fork into two rivers. So, if the river of time can be bent into a pretzel, create whirlpools and fork into two rivers, then time travel cannot be ruled out.
(More on Techland: Albert Einstein’s Theory of Relativity On Display For First Time)
Now, what would allow you to bend time into a pretzel? The answer to that is energy. In Back to the Future, it was the DeLorean. In Hot Tub, it’s the energy of hot water. In Time Traveler’s Wife, it was an epileptic fit. In the latest Star Trek movie, it was a black hole. The closest of these mechanisms probably would be the black hole. It takes an enormous amount of energy to bend time into a pretzel.
Now there is another way to do this, and that is to create a hole in time. These are called wormholes. A wormhole is a short cut through the fabric of space and time. If you take a sheet of paper and fold it in half and stick a pencil through the sheets of paper, the pencil has created a worm hole connecting two time periods. The way to visualize this to think of Alice’s looking glass. The looking glass of Alice is the wormhole. It connects you and the past with the other side of the looking glass. The energy necessary to create a wormhole or to wrap time into nuts is incredible. It’s not for us. It’s maybe for our descendants who have mastered the energy of this technology. So if one day, somebody knocks on your door and claims to be your great great great great granddaughter, don’t slam the door.
AT: What kind of a machine would you need? Hopefully the only options aren’t space ship or looking glass.
MK: You would need a machine that can harness fabulous amounts of energy to open a gateway, a portal, between the present and the past. Then the other big question raised in movies like Back to the Future, is what happens if you meet your teenage mother before you’re born and she falls in love with you. Well, you’re in deep doo-doo if that happens.
How do you resolve the paradox? The answer is quite simple. If the river of time forks and you get into the hot tub, you’re basically meeting someone else’s teenage mother who looks like your teenage mother, but it’s not really your own. You’ve opened up a parallel quantum reality and so even though that person looks like your mother, or your friend’s mother, it’s not. That’s how scientists can resolve all time travel paradoxes. If the river of time forks into two rivers, and your time machine allowed you to jump stream, from one stream to the next, but your stream is fixed, you cannot change your own past. You’re changing somebody else’s past.