Einstein and time travel

[Razi Abid]

Hello friends,
Einstein proved that if an object travels in a vacuum nearly at the speed of light, the result will be that the object will be transfered in to future. One of my proffesors said that if a rocket travels round the earth in space, with the speed of light for 1 year, then already a decade would have been passed on Earth. Is this TRUE, please justify.
with regards,
Razi

[HallsofIvy]

Neither of those statemenst is true in the way "time travel" is normally understood.
The first is true in the sense that we are all "travelling" into the future (at the rate of one second per second!) all the time and that can be "accelerated". If you travels with a speed, relative to the earth, of approximately 99.5% the speed of light then you experience time changing at only one hour for 10 hours on the earth. After one year of travel, 10 years would have passed on earth. That is not exactly what I would call "time travel" or being "transferred into the future".

That is straight line motion. It is not at all clear (to me!) what would happen if you spent a year traveling in a circle at 99.5% the speed of light. Surely you professor did not actually say "at the speed of light"- that is impossible.

[Razi Abid]

sorry, i remember that my proffesor said that if we travel nearly the speed of light. I just forgot to write the nearly in between.