The space-time continuim and traveling at the speed of light...?

Question

So if I find a way to somehow travel faster than light I can supposedly go back in time, right? But If I were to go back in time, I would either travel backwards to the point where I went to the speed of light, then go faster than light, then go back in time to the point where I went faster than light and I would be stuck in an endless cycle of speeding up and going back in time to speed up again? Or would I travel to the point of the speed of light, (And according to science, time stops when you reach the speed of light) and time would pause, and I would be stuck there for all eternity? And If I was stuck like that, and someone were to pass by the area where I achieved light speed, what would they see? Would they see me continuing at the speed of light, or would I simply vanish?

Answer 1

Yes, according to special relativity, time would stop (as viewed by an outside observer) if you were somehow able to go the speed of light. That doesn't mean time would run backwards if you could go faster than light.

You could never go the speed of light anyway. As you approach that speed your mass becomes infinite, which would mean that you'd need an infinite amount of energy to keep accelerating. Only massless particles like photons (light) can travel at the speed of light.

Answer 2

Hello fun -

Sorry, you cannot have it both ways. You are attempting to draw some logical results from a premise that doesn't make sense to begin with. First, you cannot reach the speed of light, as far as we know. So any conclusion drawn from that premise is sort of interesting, but also moot. If you were to approach the speed of light (like 99.5%), then time would slow down for you relative to others that are not traveling with you. You would not notice any difference; everything would appear the same in your frame of reference. However, you would return to your world long after your friends had perished from old age. In a sense, this represents travel into the future, not time running backward. Once you reached this future condition - essentially by aging slower than your acquaintances - you could not return. There is no way to travel back in time that we are aware of. Time travel in this sense is only based on the different times measured by different people traveling at different speeds. This understanding by Einstein is now over-100 year old knowledge that has been demonstrated repeatedly. It has nothing to do with the classic time travel envisioned by H.G. Wells et al. In fact, Einstein had no interest in the subject of time travel, since he could not understand it as anything other than science fiction - which he did not particularly appreciate.

Answer 3

Time doesn't stop when you reach the speed of light, according to current science. Particle theorists believe that there are particles called tachyons which move faster than the speed of light. They believe this because information can travel faster than the speed of light-- when a particle miles away from another particle was sent on a spin, another particle miles away was observed to start spinning at the exact same time as the other particle in the opposite direction. This has been observed over vast, vast distances.

Things can definitely move faster than the speed of light. We're just not sure what those things are.

As far as people seeing you at light speed, it has been suggested that if you were moving at a speed that great, others would view you as moving profoundly slowly and you would view them as moving profoundly slowly. Likewise, anything also moving at the speed of light would percieve you as moving at a normal speed-- not slowed down like those moving slower. (I believe this has something to do with atomic coherence, but I don't want to get any nearer to Schrodinger's cat.)

I really can't even begin to touch the bits about the space-time continuum without getting a little tl;dr, so I'll leave it at saying that travelling faster than light doesn't mean travelling through the quantum dimension of 'time,' and that watching something move at the speed of light, if we could even comprehend it, would be a little like an optical version of the VEEEEEHN of passing NASCAR racecars.

(Of course, as mentioned above, this is all theoretical as a person isn't made out of the right kind of stuff to travel at super-light speeds.)