Black holes are known as the omnivorous destroyers of stars. In reality
black holes not only take but give. Near their event horizons, where
space is so drastically warped, black holes spawn particle-antiparticle
pairs out of sheer vacuum. In some cases one of the pair escapes beyond
the horizon while its counterpart is pulled back into the hole. Thus
black holes can shed energy in the form of this "Hawking radiation."
Physicists hope to bring this whole process down to earth by manufacturing
tiny black holes amid the stupendous smashups of protons at the Large
Hadron Collider (LHC) being built at CERN. Until recently theorists
thought gravity was so weak compared to the other forces that it, and
gravitationally bound objects like black holes, could be studied on
an equal footing with the other forces like the strong nuclear force
only at energies of 1019 GeV.
In the past few years, though, some models featuring extra spatial
dimensions hint that the unification of the forces, including gravity,
might set in at much more modest energies, even in the TeV realm of
the LHC. Thus one can contemplate forming a TeV-mass black hole even
as one can imagine creating new particles in that mass range.
But what would a black hole look like? Savas Dimopoulos of Stanford
(650-723-4231) and Greg Landsberg of Brown University (firstname.lastname@example.org,
401-863-1464) have drawn a picture in which proton-proton collisions
could create black holes with a cross section (likelihood of creation)
only about a factor of ten less than for producing top quarks and at
a rate of up to one per second (see figure).
A black hole produced in this way would quickly decay, not in the usual
particle way but in a furious burst of Hawking radiation. A particularly
striking signature of the black hole would involve an electron, muon,
and photon in the final state of debris particles. Properties of Hawking
radiation could tell physicists about the shape of extra spatial dimensions.
A possibility of recreating the early moments of the universe in the
lab would further unite particle physics and cosmology (Dimopoulous
and Landsberg, Physical Review Letters, 15 October 2001.)