The claimed dangers of the LHC particle collisions, which began in November 2009, include doomsday scenarios involving the production of stable micro black holes and the creation of hypothetical particles called strangelets.[3]

Although the Standard Model of particle physics predicts that LHC energies are far too low to create black holes, some extensions of the Standard Model posit the existence of extra spatial dimensions, in which it would be possible to create micro black holes at the LHC at a rate of the order of one per second.[59][60][61][62][63] According to the standard calculations these are harmless because they would quickly decay by Hawking radiation.[61] Hawking radiation is a thermal radiation predicted to be emitted by black holes due to quantum effects. Because Hawking radiation allows black holes to lose mass, black holes that lose more matter than they gain through other means are expected to dissipate, shrink, and ultimately vanish. Smaller micro black holes (MBHs), which could be produced at the LHC, are currently predicted by theory to be larger net emitters of radiation than larger black holes, and to shrink and dissipate instantly.[64] The LHC Safety Assessment Group (LSAG) indicates that "there is broad consensus among physicists on the reality of Hawking radiation, but so far no experiment has had the sensitivity required to find direct evidence for it."[5]
According to the LSAG, even if micro black holes were produced by the LHC and were stable, they would be unable to accrete matter in a manner dangerous for the Earth. They would also have been produced by cosmic rays and have stopped in neutron stars and white dwarfs, and the stability of these astronomical bodies means that they cannot be dangerous:[5][65]
“ Stable black holes could be either electrically charged or neutral. [...] If stable microscopic black holes had no electric charge, their interactions with the Earth would be very weak. Those produced by cosmic rays would pass harmlessly through the Earth into space, whereas those produced by the LHC could remain on Earth. However, there are much larger and denser astronomical bodies than the Earth in the Universe. Black holes produced in cosmic-ray collisions with bodies such as neutron stars and white dwarf stars would be brought to rest. The continued existence of such dense bodies, as well as the Earth, rules out the possibility of the LHC producing any dangerous black holes.[6]