and
From what I can tell it's a bit like the LFS collision physics. The thingamies are going to hit each other really fast and they believe this will create matter. What they dont know is exactly what type of matter will be created.
Somewhere else it was asked recently why dead stars become iron, and that's because iron is the most stable element at a sub-atomic level. Why dead stars need to be stable is quite complicated, but basically they're not down with the whole emo thing in their after life.
When the big discy thing under Geneva impacts its first proton thingamigigs what they hope will happen is that the vibrational frequency of the strings they believe build these proton thingamies will change, so that instead of creating light energy they are instead creating something else. This could be anything from matter, to anti-matter, to nuclear energy (no dont worry, not the Hiroshima kind, although honestly who'd miss Geneva anyway?) or a combination of all of these.
The plan is to do this under a number of really big sensor type things that can measure all sorts of interesting data. They think that they will re-enact the big bang at a miniscule level.
One of the problems with doing this is we dont know what matter will be created, and there is no reason to assume that the Quark thingamies will be the same as those in our current universe. It could be a 'strange' Quark thingamy that's more stable than our own, in which case anything that comes into contact with it - much like a dying sun becomes iron - will turn into stranglet matter.
This rather unappealling and slow death doomsday scenario is of course hypothesis bred from paranoia, but is not without foundation - I mean, the whole string theory at the moment is a science relying on faith in the first place. The mathematical models it is based on (there are 5 different ones under M-Theory, i'm not sure why they need more than one, I figure scientists are just gready) so if we can believe in the string theory, we can believe it's going to screw us over too - much like God's do.
Infact string theory can arguably explain God too, if a piece of string is halved in width it doubles in length (ok it gets week here as string is a singular dimension, but it is basically how string theory works), at a width of 0 length would therefor become infinite, and thus you achieve omnipresence. However you cannot reach 0 mathematically without subtracting (which doesnt work in the mathematical model) and therefore 0 cannot exist, God therefore is nothing and nothing does not exist. Assuming God is answering to a piece of string anyway, but at least we know now that the flying spaghetti monster didnt make him.
Oh hey do I win that prize now?
