Allow to start by saying that I have no real grasp of M-theory, Supersymmetry or physics (quantum or otherwise) and I am still struggling to understand the theory of relativity. I should be the last person writing about this, not only because I'd make a fool out of myself but also because I would be giving enough misinformation to sink a merchant fleet.
Now that I got out of the way, I must admit that
there is one question that has always puzzled me. There is no law that
restricts time travel backwards.
Allow me to elaborate. Time travel
is easy, if you go forward. In fact, Russian cosmonauts and their
western counterparts, the astronauts, have been leaping forward into the
future for over 50 years.
Anyone who goes to space, orbits the
earth at great speed then comes back to earth would have travels a tiny,
tiny bit into the future. The faster you go, the slower time passes.
problem is going backwards. No one have been able to figure out a
practical way of going back in time. But is it impossible? No, just
really fucking hard. Like having to harness the power of a supernova. A
proper supernova outshines the entire galaxy it resides. In terms of
energy, that's a lot of Energizer bunnies.
At the end of the day,
we're talking about something which is still possible, so surely in the
future someone will figure out how to build a flux capacitor and stick
it in a DeLorean and make some kid's parents meet at the 'Enchantment
Under the Sea', right?
Right. So, where are the time travellers? Where's Marty Mcfly? Where's Kyle Reese? Where the fuck is Bill and Tedd?!
See the problem?
Well, there are a few possibilities.
One- We are either destroyed or we destroy our selves before that happens.
Two- We are wrong and it's just plain impossible to do.
Three- All time travellers have incredible disguises that stop us 21st century people from detecting them.
I don't like any of those answers. But what about this? How about that once you go to the past you can never go back?
think of time as a straight line. As we move through time, every
action, every decision we make branches out into an alternative.
have a hot dog. Do I want boring Tomato sauce or do I want mayo,
mustard, sauerkraut and avocado? Each one of those decisions will
trigger a new branch in the timeline.
So say that you travel back in time. You could end up in any of the alternative timelines!
You could arrive to a place where the internet was never invented or where modern humans never evolved.
let's just say you went back to the same timeline you came from. The
very fact that you've arrived in the past would trigger an alternative
timeline. We would be none the wiser that you went to the past. And if
you managed to come back to your original timeline, no matter what you
did everything would still be the same, because whatever you did, it
triggered diverging timelines.
That's why we don't see time
travellers. Because they're all hanging around in different timelines to
ours, and those are infinite.
Mind you, that is not to say that we'll never get one, it's just that it's likely to make it that much rarer.