The Chaplin Time Traveler: What Does Science Say?

Is time travel really possible? We revisit our chat with time travel expert, physicist Dr. Michio Kaku, for the science behind the theories.

Host of the Science Channel’s Sci Fi Science: Physics of the Impossible, Kaku schooled us in the possible reality of time travel back in March when Hot Tub Time Machine had us all focused on Hollywood’s junk science. Now we’re buzzing again, wondering if the image of a woman on a cell phone from a 1923 film starring Charlie Chaplin is proof of our ability to jump through time. While Hollywood’s version of time travel via hot tub or DeLorean may not be possible, Kaku admits that science doesn’t rule it out entirely. (Read the entire interview on Techland.)

On the possibility of time travel:

“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.”

On altering your own past:

“Then 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.”

On how to build a real time machine:

“In reality, what’s missing is something to stabilize the wormhole. Some scientists are skeptical because the wormhole may close on you because it’s unstable. To stabilize a wormhole, you have to have something called negative matter. Negative matter would cheat the gateway open and make sure it doesn’t close on you as you walk through the gateway. Now, we’ve never seen negative matter before, but if it does exist, if we can find negative matter, it would be the key element in a time machine.”

On our time travel time frame:

“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.”