>>1
Umm, no? I assume you're talking about the LHC. Given that collisions with energies considerably in excess of what it can generate happen on the moon etc daily, if it was going to be a problem we would have been wiped out a long time ago.
If you want something to worry about death from space try gamma ray bursters, uncharted comets / asteroids, nearby stars going supernova ...
>>2
Some of the really nerdy hard SF found in early compilations / pulp magazines is about as impenetrable. Basically : we think there might be a particle of gravity (graviton), but it doesn't really fit standard models and is almost impossible to detect. There are another 2 theories to explain it, loop quantum gravity and string theory, but both have so far proved impossible to test.