Concerns have been voiced that the CERN
LHC experiment will consume and destroy Earth.
What is the LHC experiment? It stands for Large Hadron Collider. The experiment will accelerate matter in a big ring and make it collide at very high speeds. The resulting collisions can create exotic matter, for example tiny black holes which it has been said will dissipate before they grow, or maybe strangelets - matter unknown to our universe at this time - which will feast on reality like viruses or prions. All this might happen in the course of an experiment designed to recreate conditions at the big bang.
The speed at which such a catastrophe might take place raises the question whether we would even have time to notice it. Also, the collision results are subject to randomness. If we side with the many worlds interpretation of quantum mechanics, this means that in some possible universe we will survive and there will be no world-destroying bang at CERN.
Thinking like this means to apply the Anthropic Principle, which in its weak and most abstract wording states - in my own words - that "A series of observations in a universe must allow the observer to coexist with it for the duration of the observation". While the observer might be just a tiny particle, in the case of CERN it is the entire humanity - to reword the principle to this case, we cannot observe a big disastrous bang at CERN because we cannot survive it long enough.
This way, the Anthropic Principle introduces an Anthropic Bias into observations at CERN - it will appear to the scientists that certain collision results that are possible in theory will never be observed. And people warning of catastrophies will be disappointed as well, since they can not reap the rewards of being right.