You may have heard about the possibility that the Large Hadron Collider is being sabotaged from the future.
That may sound preposterous, but it really is quite reasonable, once you think about it a little.
Let's start with the obvious:
Suppose you travel back in time and kill your grandfather. Then you wouldn't exist. And you couldn't travel back in time. And that's a paradox.
Then there is the anti-paradox:
Suppose you can't travel back in time. Because you didn't save him, your grandfather died. Ergo you don't exist.
That's not a paradox, but suppose time travel is possible: that means you can go back in time, save your grandfather, and thus make your own existence possible, ergo allowing you to save him.
As soon as you allow for time traveling to be possible, the solution for paradoxes is obvious: you can´t change change the past because the future won't let you. The future "faction" that tries to preserve the past will always win, because the past is fixed.
So, if you travel back in time and try to kill your grandfather by shooting him in the head, another person from the future will appear behind you and disarm you. Or appear behind you and kill you as soon as you had the idea to travel in time in the first place.
Or your kid will drop a coke bottle on your time machine just before you used it to kill his great-gramps.
The exact mechanism used to prevent you from becoming a paradox is unknown to you because you need to go further "forward" to know it.
Now, back to the LHC: if in the future there is knowledge about time travel, and there is knowledge about how the LHC may destroy the world_ then maybe some time tourist decided to see how humanity dressed in the pre-ice-age era, comes to 2009 and while eating a sandwich, somehow spooks a bird which then drops a piece of bread in the machinery.
Which of course, brings me to the best time-travel show on TV: "Mickey Mouse Clubhouse".
If you don't have an under-4 kid, grandson or nephew, you probably don't know it, but let me give you a summary of each darn episode.
Something "bad" happens (Goofy has a cold)
A solution is proposed (Give Goofy some Minniestrone soup)
A flying ideogram of a mouse called Toodles shows a collection of tools:
Giant candy cane
Something else "bad" happens (Pete wants the soup)
The tools are exactly what's needed to solve the problems presented to accomplish the proposed solution (You can use the seesaw to move giant rocks blocking your path).
This is obviously a case of the future preventing something from happening. How else would Toodles know what tools to choose before they are needed? There was no way to guess that a giant rock would block the ravine through which Mickey and Minnie would try to escape from Pete! 
So, whenever you need to think about paradox prevention, remember Mickey and his friends and just call Toodles.