H.G. Wells coined the term "time machine" all the way back in 1895, just a decade before Einstein published his groundbreaking paper on special relativity that would begin show how time travel is possible. The fascination with using technology to look into the past or the future hasn't faded in the last century. And as the thought experiment endures, you have to wonder: When will we finally do it—and why?

Kip Thorne, consulting scientist on Interstellar, says it doesn't really matter, as long as we try.

"First, let me say that [time travel] already is happening," Thorne said in a recent interview, when I asked him about how we might travel forward in time. "The Global Positioning System (GPS) I use to navigate my smartphone has to deal with that. Time is flowing more slowly for us than it is for something on the satellite."

That might sound obvious if you've got a passing familiarity with the basics of time. Based on the theory of relativity, time runs more quickly or more slowly for different objects thanks to the effect of time dilation. Based on Einstein's theories of relativity, we know that the passing of time varies for different objects depending on the gravitational pull and the speed the objects are moving. That's why a GPS system must make slight adjustments to its clock based on the fact that time flows more quickly for satellites zooming around the Earth in orbit. You can read a full explanation of how that works here and here.

But that's the time travel lite. What about the real sci-fi stuff?

To read more and view the video, click here.