[3] Some hypotheses involving additional space dimensions predict that micro black holes could be formed at energies as low as the TeV range, which are available in particle accelerators such as the Large Hadron Collider.
[citation needed] Beside the theoretical arguments, cosmic rays hitting the Earth do not produce any damage, although they reach energies in the range of hundreds of TeV.
Examples of such extensions include large extra dimensions, special cases of the Randall–Sundrum model, and string theory configurations like the GKP solutions.
In such scenarios, black hole production could possibly be an important and observable effect at the Large Hadron Collider (LHC).
The rules of general relativity would be broken, as is consistent with theories of how matter, space, and time break down around the event horizon of a black hole.
It was hypothesized by Zel'dovich and Novikov first and independently by Hawking that, shortly after the Big Bang, the Universe was dense enough for any given region of space to fit within its own Schwarzschild radius.
[1] Under optimal conditions, the Fermi Gamma-ray Space Telescope satellite, launched in June 2008, might detect experimental evidence for evaporation of nearby black holes by observing gamma ray bursts.
It has, however, been suggested that a small black hole of sufficient mass passing through the Earth would produce a detectable acoustic or seismic signal.
[21] In familiar three-dimensional gravity, the minimum energy of a microscopic black hole is 1016 TeV (equivalent to 1.6 GJ or 444 kWh), which would have to be condensed into a region on the order of the Planck length.
It was argued in 2001 that, in these circumstances, black hole production could be an important and observable effect at the LHC[4][5][6][7][22] or future higher-energy colliders.
[4][5] A paper by Choptuik and Pretorius, published in 2010 in Physical Review Letters, presented a computer-generated proof that micro black holes must form from two colliding particles with sufficient energy, which might be allowable at the energies of the LHC if additional dimensions are present other than the customary four (three spatial, one temporal).
[23][24] Hawking's calculation[2] and more general quantum mechanical arguments predict that micro black holes evaporate almost instantaneously.
Additional safety arguments beyond those based on Hawking radiation were given in the paper,[25][26] which showed that in hypothetical scenarios with stable micro black holes massive enough to destroy Earth, such black holes would have been produced by cosmic rays and would have likely already destroyed astronomical objects such as planets, stars, or stellar remnants such as neutron stars and white dwarfs.
[citation needed] Virtual micro black holes were proposed by Stephen Hawking in 1995[27] and by Fabio Scardigli in 1999 as part of a Grand Unified Theory as a quantum gravity candidate.