Micro black holes (continued)

This paper isn't new, and it may or may not have not great relevance to the issue of safety of micro black holes at the LHC. (Unfortunately, I am not an expert on gamma radiation.) But the paper is interesting for two reasons:

1. It suggests that if the LHC can produce micro black holes, then atmospheric collisions from cosmic rays may produce about 100 micro black holes a year for the entire surface of the earth. (Astute readers will recall, though, that these are different from accelerator created ones because they would have high velocity from the way they are made.)

2. It also says that even micro black holes (or, if I am reading it right, their remnants) could create high energy radiation. As this is hard to summarise, I'll just copy it here:

A charged particle being accelerated by a black hole can produce g -rays with energies in the multi-TeV range before the particle passes beyond the horizon radius provided that the curvature gradient of the space around the black hole is large enough. Such curvature gradients occur in quantum black holes, black holes whose masses are of the order the Planck mass. A calculation taking into account special relativity (but not general relativity) shows us that to produce g -ray energies in the 10 TeV range a single electronic charge would have to be accelerated by a black hole with a mass equal to five times that of the Planck mass.

The microscopic black holes needed to produce ultrahigh g -rays may be the remnants of primordial black holes. Such black holes can be produced by
• Inflationary horizon-scale fluctuations
• Density fluctuations at phase transitions and bubble formation and collapse
• Baryon isocurvature fluctuations on small scales.

Large-mass primordial black holes (M > 1015 gm) decaying via Hawking radiation [5] as described by the canonical ensemble in 4 space-time dimensions, (dM/dt)∼ −M−2, would have decayed to a Planck-size mass in the present epoch.Microscopic black holes produced in this manner could be stable if quantum gravity effects terminate the decay process.

Copious microscopic black hole production can also occur if large extra dimensions exist. In this scenario black hole production can occur as the result of the collision of particles with total center of mass energy above the effective Planck scale, which can be as low as the electroweak scale mew ∼ 1TeV. Black holes could thus be produced in collisions of high energy cosmic rays with the Earth’s atmosphere. As we show in the next Section, such black holes may live long enough to create ultrahigh g -rays even without taking quantum gravity effects into account.

Seems possibly relevant to me to the issue of the safety of the LHC at CERN, if its going to be creating thousands of little black holes and black hole remnants, many of which are going to hang around rather than zipping off into space.