Time travel also makes no sense because even if it could be accomplished it would have to be accompanied by space travel to be of any practical value. All bodies in the universe --- including yours and mine --- are in perpetual motion, even though we are not commonly aware of the motion. Earth is not where it was five minutes ago, neither in terms of its revolution around the sun nor in terms of the sun's revolution --- carrying with it all objects our solar system --- around the galaxy nor in terms of the Milky Way galaxy's travel through space. So if you went back five minutes in time from any point on Earth you sould simply end up in space unless all those spatial coordinates could also be accounted for. I always thought that just Marty McFly and his DeLorean went back to 1955. The reality is that Doc Brown would have had to arrange things so that the entire universe went back in time. That would require more gigawatts of power than even the good doctor could muster.