Is time travelling possible?

We are all time travelers
 

"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," says Davies. "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."

A phenomenon called time dilation is the key here. Time passes more slowly the closer you approach the speed of light -- an unbreakable cosmic speed limit. As such, the hands of a clock in a speeding train would move more slowly than those in a stationary clock. The difference would not be humanly noticeable, but when the train pulled back into the station, the two clocks would be off by billionths of a second. If such a train could attain 99.999 percent light speed, only 1 year would pass onboard for every 223 years back at the train station.

But speed isn't the only factor that affects time. On a much smaller scale, mass also influences time. Time slows down the closer you are to the center of a massive object. "Time runs a little bit faster in space than it does down on Earth," Davies says. "It runs a little faster on the roof than it does in the basement, and that's a measurable effect." A clock aboard an orbiting satellite experiences time dilation due to both the speed of its orbit and its greater distance from the center of Earth's gravity. "Both gravity and speed can give you a means of jumping ahead," Davies says. "So in principle, if you had enough money, you could get to the year 3000 in as short a time as you like one year, one month, whatever it takes. It is only a question of money and engineering."