In the new sci-fi hit 'Looper,' starring Bruce Willis, Joseph Gordon-Levitt and Emily Blunt, the mob uses “Loopers” and time travel to kill targets in the 30-year past. But how much of the film is based on actual hard science?

As shown in the film, criminals are sent from 2074, where killing proves to be tougher as new tracking technology makes it impossible to hide bodies, back to 2044 where a Looper awaits with a loaded gun. However, in order to protect the mob’s illegal time travel system, periodically they send back the Looper himself, thereby forcing the Looper to kill his future self and "close the loop." In the movie, a Looper named Joe (Gordon-Levitt) recognizes his future self (Willis) and hesitates, resulting in the escape of future Joe.

But is this kind of time travel in line with what we currently know about the laws of time? In a nutshell, Einstein's Theory of Relativity states that time is not an absolute quantity, but must be considered together and in relation to space. So space and time can dilate, depending on other dimensions such as speed and mass.

Theoretical physicist and cosmologist Paul Davies, (author of 'How to Build a Time Machine') says,

The short answer is that time travel into the future is not only possible, it's been done, and we've known about it for over a century. The reason that the public doesn’t seem to know about it is because the amount of time travel involved is so pitifully small that it doesn't make for a 'Doctor Who' style adventure."

Tardis is the only way to time travel

He uses the example of traveling on a train. Time passes slower the closer you approach the speed of light. Therefore, the hands of a clock in a speeding train rotate slower than those in a stationary clock and the two clocks would be out of sync when the train pulled into the station. By about a billionth of a second. Did the train time travel?

If however, this train could reach speeds of 99.999% light speed, then a year would pass onboard for every 223 years back at the station. This is called time dilation. Essentially, if you are sent out in a rocket, traveling close to the speed of light, the short amount of time that passes on that rocket would allow to you arrive back on Earth many years into the future.

Unfortunately, Davies says that,  "Going back into the past is a whole different kettle of fish." Meanwhile, Edward Farhi, the Director at the Center for Theoretical Physics at MIT agrees saying that, “most physicists think you can go forward, but coming back is much more problematic. If you could go back in time, you could prevent your parents from getting together and making you.”

Or your mom tries to seduce you in the past.

Farhi actually calculated that the amount of mass that would have to be destroyed to make a time machine work would essentially break apart half the universe.

So, while 'Looper's' storyline is looking doubtful, we'll still see time travel movies and shows being produced in their masses. Rian Johnson, the director of 'Looper,' says that, "Time travel movies appeal to us because the characters cheat time. We know that we only have a finite amount of time on this earth, and being able to elongate that is quite a fantasy." Fantasy or not, we're all relieved to hear that death by club in the Stone Age is out of the question.