Another solution to Fermi's Paradox
Here's another solution to Fermi's Paradox: There are no interstellar capable civilizations in the universe because the Laws of Physics contains a booby trap. Eventually every technological civilization in the universe builds a particle accellerator beyond a certain limit, creats a black hole by accident and then the whole planet goes "poof!".
Gary
p.s. Not likely because cosmic rays hitting the upper atmosphere will always create more energetic phenomena than possible from an aritificial particle accelerator.