Time travel is not possible

If it is, we will have been visited by time travelers.

Feel free to disagree and/or flame!

interesting but it is not exactly "time travel"
there is man made time and natural time.
so you could not type in 1989 and go to the year 1989
because the earth runs off of natural time.
and as for the speed of light... you would have to have some sort of machine to cancel out the g's of force pushing against you. but it might be possible. but it would be erratic, unreliable, and expensive.