WhatGravitas
Explorer
Not quite.
Dark matter is some sort of matter out there that's dark, i.e. we cannot see it. We cannot detect it... but we know it's out there, because we can see how there is some mass out there exerting gravity. It's a fancy word for "some unknown stuff out there".
Exotic matter, however, matter that doesn't behave normal baryonic matter, i.e. it is exotic. It has strange properties like negative mass, don't interact with normal matter... it's a fancy catch-all for "weird speculative stuff" (stuff as in matter, i.e. things you can touch).
Now, dark matter may consist of exotic matter, but we simply don't know beyond "there's something out there" - perhaps dark matter isn't exotic matter but something completely different.
On the black holes in the LHC: If they're really resulting from the experiment (what I doubt) - They're tiny. Really tiny. Like a Planck length (~10^-35 m - atoms are around ~10^-10 m). And they only weigh as much as a atom, i.e. have neglegible gravity. I'm more afraid of getting under a car, winning in the lottery and seeing a nuclear war - in one day! - than these micro-buggers.
Trust me, I study physics! (yeah, I'm a undergrad, so perhaps you shouldn't trust me)
Cheers, LT.
