What would happen (theorhetically) if you could travel faster than light

[Mick UK]

If humans could travel say 10x faster than the speed of light, and set off from earth for say one year in a straight line, and then looked back at the light from the Earth, i pressume you would be looking back in time by 9 years, so my question is, if you then traveled back to Earth at 10x the speed of light for one year, you would arrive 8 years ahead of the light from earth, so would you have gone back in time??

[nicelookie]

Ignoring the relativistic effect, I think you will be back to the same time.

However, you will be able to see the Earth 8 years ago at the location where you stand after travelling 1 year with 10x speed of light.

Let's do again the calculation, first part is correct, you can see the light that emit from Earth 9 years ago. But, if you travel back at 10x speed of light, you are actually fast forwarding, that is, at t=0, you see 9 years ago, then 8 years, 7 years.....But, since you are travelling 2 years, the "frame" that you are from has been 2 light years away from Earth, and you are now in the frame of 2 years later. And this 2 years is the year that you travel, hence it's the same.

Hope my English is understandable.

[ollypenrice]

The question is unanswerable, I think., If we could do the impossible, what would it be like? It would not be impossible so we couldn't have done it...

Olly