text: if i left the earth and travelled at the speed of light for 3 yrs how much time would have gone by on earth?   as your speed increases, the speed of time around you approaches infinity, if that makes any sense. so if you were traveling at 99% the speed of light, you might see many years pass by during the three years you are travelling. if you are actually at the speed of light though, time around you moves infinitely fast, according to the formula anyway. not sure what that would really be like.