I've read many books and seen a few movies in which people travel (usually) back in time. Yesterday I finished another book "Timeline" by Michael Crichton. I wish I hadn't read it. The reason is that it's impossible to go back (or forward) in time. The past is finished and can't be reconstructed, while the future has not yet happened. Yet science fiction writers talk about multiverses (parallel universes) where time has stood still. 

In Crichton's book, machines have been constructed that go into the parallel universe and take people back in time. Four people go back to the fourteenth century to rescue a professor who is already there. One of the four remains back in the fourteenth century, marries a duchess,  takes her to England and dies there. This is simply incredible. It also means rewriting history, as it would never have happened if he hadn't gone back from the twentieth to the fourteenth century. 

I've heard that the recently acclaimed movie "Everything, everywhere, all at once" also deals with time travel. It must be a very good film, having won the Oscar 2023 award for best film. But I still don't believe that time travel is possible.