When looking for a good definition of a paradox in the internet I found this
(logic) a statement that contradicts itself; e.g. I always lie is a paradox because if it is true it must be false
Now I think that sums up what a paradox is quite nicely. Something that cannot logically happen.
It’s the old chicken and the egg thing. Nether can have come first, as the chicken needed to come from the egg, but the egg needed to have been laid by a chicken. Evolution beat the fun out of that though.
Let me give you an example. You cannot go back in time and kill your grandfather before your parent is born. Why is that a paradox? Well as you do, you would only have one parent, and everyone knows that you need two people, both male and female to make a child.
This messes with your head slightly as you would only have one parent, therefore you would never be born, therefore you could not go back to kill your grandfather to stop you being born. Make sense?
Now that’s the general theory of it. But as we can’t time travel, so nobody has actually ever managed to prove or disprove such a theory. What if however, the universe in all its oddness was able to sustain paradoxical events? What if you were able to kill your own grandfather, but in the process you rewrote your own history.
Okay, I am maybe bordering on the realm of science fiction here, but for the purpose of this post let’s assume that paradoxes are sustainable and that we have mastered the ability to time travel.
So if you did go back in time and kill one of the relatives you are a direct descendant of, (not that you would want to) what would happen? The second you killed them would you change there and then? Assuming you wouldn’t fade away, or instantly disappear. Then again is there the possibility you couldn’t kill them?
Time travel being possible, we would probably be jumping through wormholes, and who’s to say we wouldn’t change time, but instead enter a whole new, almost identical reality? Would you really be killing your relative?
Could you change yourself? Like in Doctor Who, actually re-wright your own timestream? You were still born, but just to slightly different parents, with the DNA combination just perfect to make you, or something almost the same as you.
Then again what if (again like in Doctor Who) you had a paradox machine like the TARDIS? If you were able to sustain the paradox (only for a short amount of time before the universe imploded) what would actually happen? Well in theory everything would carry on as normal.
A TARDIS converted into a paradox machine
How about a planet, is it possible to destroy your entire planet before your birth? Who knows, as that is all highly theoretical 
Then again, maybe you can only cause a paradoxical event if you mess with your own timestream. So long as you don’t go disrupting your own history, the universe doesn’t mind what you do…
Another great example of a paradox would be teleportation over long distances. Why? Well if you are going to travel several million lightyears away, in less than a single second, then you would get there before you started, relative to your own timestream, if that makes any sense…
Place 1 – ZAP!!! You travel faster than light (and theoretically time itself) so by the time you are there, the light from the new place you have reached won’t reach the old place until thousands of years later, why? As you traveled faster than the speed of light.
Therefore at some point in the future you would be able to see yourself teleporting to the spot millions of lightyears away, hence at some time there is no you at all, whilst at others there is more than one you. But is that really you? If your atoms are being dissembled at one place and then you are being re-assembled at another, possibly out of new atoms, even though genetically identical, is it still you?
That’s another post though, I have a great example of that, it involves a boat and a future article
Hopefully you have learnt a bit, and hopefully you will have some questions and comments throw at me!
