I was watching a BBC documentary about time travel. They were explaining that it is OK to travel in the future. We do that every day. Time slows down when we travel fast. That means we can travel into the future. Here is how, you travel fast, your clock slows down. Then when you stop you come back to “present”, which is “future” to you, because your clock was slow for some time.
But there is a paradox about traveling in to the past. Here is how. Suppose I go back in the past and persuade my father not to marry my mother. Then I will never be born. But that’s a problem because I WAS born and caused this. The documentary was explaining how this paradox can be explained using “parallel universes”. This is bizarre. If you see the documentary you will realize how bizarre it sounds.
Then I travelled in the past for some 100-200 years. There was this crazy professor named Ratherford and he was telling us that the book that I was holding in my hand is almost entirely empty. There are some tiny particles named nucleus that accounts for most of the weight of the book and then there are electrons that circle the nucleus whose positions are chancy. I mean how much more bizarre can it get! Then came another crazy professor who was telling people that time travels slower when people travel fast. Of course I did not believe either of these two crazy professors.
You know what happened? Within 40-50 there were two million people dead because of these theories. Those two million corpses were real. Then I learned to take these people seriously, no matter how fantastic they sound.