Theoretically, if a man left today, flying away from Earth at twice the speed of light for one year, then returned to earth at the same speed, would the day he got back be the same day he originally left?

Gnomon

Theoretically, the man can't travel faster than light, so it is impossible to say what would happen. Dec 05 03, 5:24 PM

Senior Moments

His speed is irrelevant as the question states that the man travels for one year in each direction. His speed only determines how far he travels each way. He would return two years later than the day he left. Dec 05 03, 5:29 PM

Hamlet.

Time dilation plays a major role in Einstein's Theory of Relativity, which states that if someone were able to travel faster than the speed of light, time would stop. Since no one can travel at that speed, the rule has been explained in time dilation: the faster one travels, the slower time moves. This means if someone is traveling quickly through space, time compensates for that motion - for, according to the Special Theory of Relativity, the laws of physics are the same no matter what a person's speed... Dec 05 03, 5:59 PM

gmackematix

I presume, SM, that the time of two years measured is relative to the traveller and would not necessarily be the same as time measured on Earth. Time dilates (i.e. appears to slow down) relative to the observer as speeds of an object become near that of light. I'm sure I have heard of such things as tachyons, problem particles that seem to travel faster than light so the question would presumably apply to those. I'm not sure if any experiments have confirmed how time passes relative to an object exceeding the speed of light so I can't give any definite answer to this question. Dec 05 03, 10:39 PM