(This be the first Talk Like a Pirate Day I remembered it on time to talk like a pirate! Arrr! Of course, it be very hard to talk or type in that vernacular for very long [it don't come natural, see], so I be droppin' it right quick.)
If you need reassurance: The answer to the Large Hadron Collider question that may be on your mind.
Lots of people have been concerned about the possibility of very bad things happening; they've named baby black holes, exotic matter unimagined, and the creation of dangerous amounts of antimatter as potential risks. Of course, according to the modern model of physics, these things will all fizzle out before they cause serious problems, so these are probably unfounded fears.
Of course, it's also possible that this will cause something even more unforseen to happen.
The Collider is a device that has been built in humanity's quest for knowledge. A little knowledge is a dangerous thing; a lot of knowledge is in some ways less dangerous, but in others far more so. It's possible, though, that it can answer questions we don't want answered.
Some examples of answers we don't want:
The answer to Life, the Universe, and Everything: 42.
(This really is the worst possible answer, simply because of the confusion factor.)
The existence of God: Yes, now...
Whether the Universe is even more terrible than we envision it to be: Yes.
The winner of the upcoming US presidential election: The candidate you didn't want.
I could come up with more, I'm sure, but that's enough for now. Signing off.