Now, to be fair, possible doesn't mean easy, but still. The energy requirements are so far beyond what our civilization can produce that they're hard to imagine, but the point is that the laws of physics don't explicitly prevent it from happening. According to astrophysicist Ethan Siegal, what you need is a pair of entangled wormholes and a way to accelerate one end to the speed of light. Then someone in the future could pass through the wormhole and arrive in the past. The only issue is that it's a one-way trip, at least through the wormhole.
As far as returning to the present, that actually is so easy (relative to going through everything that you would have to do to create and accelerate time-entangled wormholes, of course) it doesn't even get a mention in the article. We already know how to do that, and it's a mainstay of every introduction to relativity theory. You just go really, really fast. That's how the "twins paradox" works. The fast-moving twin who doesn't age isn't rendered ageless, he or she experiences dilated time - in effect, the same thing as jumping forward in time.
So if you jump into the past via a wormhole, it's entirely possible for you to get back. Just fly through space at very close to the speed of light and make a really big loop that starts and ends at the earth. When you finish your journey, hardly any time will have passed for you but many years will have passed on earth and you will have traveled in time in the other direction.
Time travel has been the holy grail of science for centuries but it could finally be within our grasp. There is just one problem, we might not be able to return to the present from the past.
Astrophysicist Ethan Siegel has outlined in his blog Starts With a Bang how the theoretical rules of physics might allow a way to use wormholes to travel back in time. A wormhole which is still at one end and as fast as the speed of light at the other could provide the basis for humans to step back into another era. This will not be easy, and considering how many people get confused when the clocks go forward or back the chances of successfully pulling off the creation of time travelling wormholes could be tough.
Siegal said: ‘If, 40 years ago, someone had created such a pair of entangled wormholes and sent them off on this journey, it would be possible to step into one of them today, in 2017, and wind up back in time at the mouth of the other one back in 1978. ‘The only issue is that you yourself couldn’t also have been at that location back in 1978; you needed to be with the other end of the wormhole, or traveling through space to try and catch up with.’
As far as returning to the present, that actually is so easy (relative to going through everything that you would have to do to create and accelerate time-entangled wormholes, of course) it doesn't even get a mention in the article. We already know how to do that, and it's a mainstay of every introduction to relativity theory. You just go really, really fast. That's how the "twins paradox" works. The fast-moving twin who doesn't age isn't rendered ageless, he or she experiences dilated time - in effect, the same thing as jumping forward in time.
So if you jump into the past via a wormhole, it's entirely possible for you to get back. Just fly through space at very close to the speed of light and make a really big loop that starts and ends at the earth. When you finish your journey, hardly any time will have passed for you but many years will have passed on earth and you will have traveled in time in the other direction.







