The Lightspeed Problem

One of the principle arguments brought forward by those who claim that is it vitually impossible for E.T.s to visit earth, is the distances involved and the time needed to travel even to the closest stars.

The energy requirements and techical barriers are often brought up, but these are just engneering problems, the fact that they are currently impossible for us is really irrelevant.

But the lightspeed barrier is a fundamental limit. No amount of engineering or technology is going to get around it. It is true that our knowledge of physics is not complete, but new theories extend the old ones, they don’t contradict them.

The big problem is that faster than light travel means travelling back in time, which causes logical paradoxes. You can get around it by introducing multiverses and alternate timelines. But woud you really want to travel faster than light if everytime you did it you ended up in a paralell universe that you could presumably never get back from?

This has always been a sticking point for me. But I have recently become aware of two possible solutions to the problem.

For a person travelling close to lightspeed, time slows down. So for the person travelling, it is possible to travel a thousands light years in only a day. The problem is, that for everyone else, a thousand years will have past. This means that you could travel a thousand light years in one day, return home the next day, but you would come back to a planet where 2 thousand years had passed. This is obviously a problem. However: it is reasonable to suppose that a space fairing civiization would no longer be planet bound. If you go off at lightspeed in one direction, and some on else goes off at lightspeed in another direction, then you can meet back up and the same amount of time will have passed for both of you. This also has the consequence that aliens visitng the earth today could be the same ones who have visited the earth thousands of years ago, since it could be only a few months have passed for them. Apparently, the time-travel paradox only applies in special relativity, ie. flat-spacetime. In curved space-time it is possible to travel faster than light without violating causality. This is something that I was completely un aware of. Unfortunately, I don’t have time to look into the details and how that would work. However, it means that warp-drives could in principle be possible. The remaining barrier is that they require negative energy. Negative energy does exist in a certain sense. In hawking radiation, a particle with negative energy falls into the black hole, which causes the black hole to evaporate. As far as we know, negative energy doesn’t exist, but it does not contradict and of the known laws of physics. So it is possible that we could discover new physics that would allow for warp-drives.