And I welcome you all to our end.
No, seriously, I don't think it's likely something bad will happen, but I find it possible. And given the consequences (the whole world cracking and falling to its core now turned into a black hole) I think that's unacceptable.
I find it terrifying the speech that I've seen on this subject.
Some high profile scientists said "according to the standard model, you would need more than five dimensions for a black hole to develop, and even if it developed, it wouldn't last for long". Uh... IT IS THE FRACKING STANDARD MODEL YOU ARE TRYING TO REFINE!!! That line of reasoning, analyzing things with your current knowledge at hand applies to every possible situation int he universe BUT THIS ONE. Your "best guess" here is not good enough when it would be feasible that your model is wrong and the whole thing ends up with me being smashed with you in a single point.
One scientist said "the chances of that happening are one in fifty million". What? Even if you apply no margin of safety, that's like shooting in the back of the head 120 people (considering that equivalent to one in 50.000.000 of killing six billion, it can be argued that the later is actually much worse even mathematically). And then they claim they have reasonable safety margins, and I can beleive that, but those are safety margins in their NUMBERS, not in their MODELS. A simple, tiny change in the standard model might make black holes not only likely, but inevitable. And you don't know that, as you haven't researched all possible models, and you couldn't.
I've also heard scientists saying "similar collisions must happen in other parts of the universe, and we don't see that happening". Huh. How would you be able to "see" a tiny black hole? How do you know the missing mass in the universe is not formed by large amounts of small black holes created when such a high energy event occurred and ate whatever was around it?
I'm not a fanatic. You can do that sort of bet when you are playing with models that are extremely well established. But when you are breaking new ground trying to validate your current knowledge, you can't make experiments that might destroy the whole planet if your model was wrong. I would even accept it if we couldn't even figure out what could go wrong, but when the stakes are so high, relying on the probability of the event occurring is plain wrong. It is whe most wrong than anyone has ever been in history. Even if in the end, their models turn out right and nothing happens (until they say "hey, nothing happened the last time, let's build a bigger one, with a chance of one in six!).