Richard H repliedThe likelihood of it creating a lasting black hole is very small - even if a black hole is created it may disappear again in an instant. By the physics we know at the moment, the energy available in the accelerator is 3 orders of magnitude smaller than that required to create a black hole. It is only under unproven theoretical physics that the holes appear. By the same theories, we should already be seeing black holes in the atmosphere. Although the energies involved in the LHC are large, they are as nothing to the high energy particles that pass through the atmosphere each day. These are far more likely to create a black hole, and the planet has survived 4.6 billion years already.
A lot of the stories have been spun out of all proportion by the media, implying that the world will definitely end whenever the accelerator is turned on. Humanity is far more likely to be wiped out by many other causes than a black hole under Switzerland.

thepissedpirate repliedNo serious physicist is even slightly concerned about what's going to happen.

The things that some whack-jobs are concerned about (microscopic black holes, strange matter), if they were going to be problems would have caused problems already.

Stable microscopic black holes, if they were going to be created, would have already been created in cosmic particle collisions that occur naturally.

If strange matter was going to turn everything else into strange matter then it would have happened in the RHIC.

Basically, the people who know more about this stuff than anybody else in the world have already thought about it in great detail, and they're so unconcerned that they're going to be there when the first collisions occur.