Jack Rogers, of Bulls, asks :-

I read recently that the Large Hadron Collider could possibly have created a microscopic black hole. In theory that tiny black hole would simply swallow anything in proximity to rapidly becoming a large one, meaning the end of Earth. Is this so?

Alick Macpherson, a University of Canterbury physics graduate who is one of the operators of CERN's Large Hadron Collider, (LHC) responded.

This is another example of science fantasy gone wild. Man-made accelerators do not deliver the centre of momentum energy required to realise such an event.

Keep in mind that for billions of years cosmic rays have been impacting the earth with energies of over 10**20 electron-volts. The fact that the earth has not yet been destroyed by a black hole created from the impact of a high energy cosmic ray gives a strong indication that black holes are very hard to create. The argument is even stronger, when you take into account that the LHC beam energies are 100 million times weaker in energy than high energy cosmic rays. To put these energies into perspective, each proton in the LHC has an energy comparable to that of a mosquito in flight

In 1932, when Rutherford and his colleagues Cockcroft and Walton first used an accelerator to artificially induce a nuclear reaction, people immediately wrote in pleading with them to not split the atom because the world could fall apart. They too overlooked that the same reactions (e.g. an alpha particle emitted from radioactive nuclei and impacting a lithium 7 nucleus) had been occuring in nature for billions of years.

For the full discussion on potential disasters scenarios that the public could think may be created in the LHC, search press.web.cern.ch for safety-lhc which looks to allay these unnecessary fears.

Having said this, the biggest concern we have is the risk of mechanical failure or accidental beam loss due to equipment failure, because there is a huge amount of energy stored in the beam and even more stored in the 27km long cryogenic system. We saw what happened in 2008 when only a fraction of that energy is released in an uncontrolled way due to mechanical failure. (Search press.web.cern.ch for analysis-lhc-incident.)