Mr. Strickland: “I noticed your band is on the roster for the dance auditions after school today. Why even bother, McFly? You don’t have a chance. You’re too much like your old man. No McFly ever amounted to anything in the history of Hill Valley!”
Marty McFly: “Yeah, well, history is gonna change.” –Back To The Future
If you’ve ever wished you could go back in time and undo that mistake you made, to have a second chance to get it right the first time, you’re certainly not alone. Indeed, for as long as the concept of time has been around, humans have dreamed about this possibility, as some of our oldest myths and stories involve traveling back in time to fix our own past, or even the pasts of our ancestors.
But from a physics point of view, this is likely impossible. Time travel is inevitable — to the future — but going to the past? That seems like much more fiction than science. While it’s an entertaining fiction, Einstein’s relativity in the Universe we have seems to prohibit it.