There are things that we, as humans, find difficult to comprehend. We live only finite lives, and our little life is rounded with a sleep. As a result, it is extremely difficult for us to comprehend the full extent and meaning of infinity… The first question we come out with is, “But what came before the beginning?” We have no experience or understanding of things that don’t have to start somewhere and struggle to come to terms with it (without the use of illegal narcotics or possibly decades of isolated meditation).
Time travel is another one of those concepts. As beings perceiving just the three standard spatial dimensions plus one rather linear one of time, we can’t wrap our heads around the paradoxes that time-travel invariably creates. The grandfather paradox is ubiquitous – If I go back in time and kill my grandfather, how did I go back in time at all?
The reason the grandfather paradox arose as the standard description for time paradoxes is once again due to limited human understanding. As a whole, people like to feel that their actions mean something. Without this, what would be the point of living at all? We like the idea of choice and free will, and that if we choose to, we can change things.
And that is why I would posit that the secret of time-travel is that there currently is no secret of time travel. All time exists, and all time is predestined, and all of the decisions that have brought us thus far happened because the alternative choices happened somewhere else. The secret is that out of all of the infinite universes and infinite time-streams and infinite possibilities, including the one where Jesus is Batman, we happen to live on a boring one.
Right now, no-one on this planet has any kind of proof that someone is bouncing about in the space-time continuum and popping up to say hi. Perhaps our reality just hasn’t got there yet. Perhaps you could argue that top-secret special spies with no identity and no social security numbers are time-travelers on super-important missions to kill future threats. But the simple fact is that right now, our reality has nothing in the public domain to prove it. If it did exist, sure it would stay top-secret for a while, but eventually they would slip up and be seen in public, or misclick the controls and turn up in Parliament instead of somewhere more subtle. Human error will always be a factor.
So my assumption is that we live in a dull reality so far. No time-travel, no aliens, no Godzilla. Maybe that’s a blessing. Although at least one of the infinite universes will have discovered time-travel by now, our stream hasn’t crossed with it yet. Maybe it never will.