Or, why time travel can’t ever happen!
I often have the same argument with people, usually when a new film or TV show featuring time hopping adventurers appears. Don’t get me wrong, I love Back to the Future and Terminator as much as anyone else. There’s nothing wrong with imagining time travel, heck I’d love to try and wrap my brain around writing a dimension bending, convoluted time travel story myself. I bet it involves a lot of post-it notes and white board timeline diagrams.
Back to reality though. Let’s assume time travel is possible. As far as I’m aware, there are theories on time and space that mean, if we were to approach the speed of light, then return to our point of origin, time would have progressed much faster than for us travelling at speed. In short, for us a day would pass, but for those left behind possibly years could go by. So far, so good.
Going backwards in time is a bit more difficult. The past has gone. It has happened and is done. Going forward just means getting to the inevitable quicker. Going back means that the past and everything that ever existed in it must still exist somewhere. I believe alternate dimensions is a considered possibility.
But let’s stick to time travel in this dimension, Back to the Future style, where you get in your time machine and simply travel to the time and date of your choice. The first problem of time travel is germs. Simply put, if you don’t get out of your time machine wearing a totally disinfected hazmat suit then you’re going to have problems. You might not get sick, but everyone you come into contact with will have no immunity whatsoever to all the highly evolved bacteria you’ll be carrying. You could literally cause a black plague size event.
Getting into time travel paradoxes about killing your own grandfather before your father is born will just melt your brain. Surely, the past has already happened so any time travellers that go back will already have made their effects on time? Unless it really is like back to the future where you can go back and change things so the future pans out differently. In this scenario maybe many people in the future will inevitably go back and change all the worst bits of history. If they do though, everything we do now is ultimately pointless as it’ll all change. The chance of any one sperm hitting its goal is incredibly low so the chance of the same one hitting the mark in a slightly altered world are astronomically impossible.
So, being that both world wars still stand and definitely happened are we to assume that we are still on the first run through? That no one in the future has been back and changed events to create the best possible history? What if it isn’t? What if this reality is the best possible? What if generations of time travellers in a distant future have spent centuries changing time over and over and this is the best they could manage? It leaves some big questions, my first being who or what was worse than Hitler?
Professor Stephen Hawking, I believe, answered the time travel debate once and for all. Not with fancy physics equations or a theory on temporal dimensions in space. He simply hosted a party for time travellers. The beauty of it being that he didn’t invite anyone until the next day. Obviously, no one showed up to that party. It’s conclusive evidence for me as anyone who could build a time machine would undoubtedly hold Professor Hawking in high esteem. At the end of the day, who could resist an opportunity to party with him?