What do we really know... about the LHC

''In a spectacular (and intentional) understatement, the physicists who first tried to put numbers on such risks - then in the context of the Relativistic Heavy Ion Collider at Brookhaven, New York, a predecessor to the LHC - referred to potentially "profound implications for health and safety". Invoking quantum chromodynamics, what we know about the gravitational conditions for creating black holes, and our knowledge of near-Earth high-energy collisions due to cosmic rays, they put the chances of a "dangerous event" at around 10-9 per year.
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In other words, conclusions about extraordinarily small probabilities require equally extraordinary care. Any estimate of the likelihood of an event occurring should take into account the chance that the analysis on which that probability has been assigned is flawed or based on error. This is the principle of epistemological uncertainty - that we can't know anything with total certainty - in action.'' [source]