At the speed of light, from who's perspective does time slow down?

it is impossible to travel at the speed of light, but if you did, time would not p at all. at .999 the speed of light, a journey to the andromeda galaxy would take, outside your time-dilation bubble, about a million years. inside the time dilation bubble (your ship) you would only experience about 12 years. so technically since when your trip is over with you are only 12 years older than when the trip began, and the rest of the universe is a million years older, you could consider it "traveling forward in time".