domingo, 13 de noviembre de 2011

Physics - The Possibility of CERN's LHC Black Holes Revisited


MIT's Technology Review reports that "It's been 10 years now since physicists first raised the possibility that particle accelerators on Earth could produce microscopic black holes. This phenomenon initially seemed hugely exciting since it hinted at a way scientists could test their ideas about quantum gravity, the theory that reconciles quantum mechanics with general relativity."

What the LHC scientists discovered, howver,  is that the energy required to create the nano black holes vastly exceeds what is possible even in the world's most powerful accelerators and even exceeds that found in the most powerful cosmic ray ever recorded.

But it appears that there various loopholes that will allow micro-black holes to form at lower energies, the most popular among the scientific community is the possibility that the universe has extra dimensions on microscopic scales that significantly weaken gravity at this level allowing microscopic black holes to form more easily.

Yet even the planet's most powerful accelerator, CERN's Large Hadron Collider, has so far failed to produce black holes with masses up to 4.5 TeV. That means any extra dimensions must be smaller than 10^-12 metres in size.

Marcus Bleicher at the Frankfurt Institute for Advanced Studies in Germany and his colleagues have tackled some of the unresolved problems concerning possible black hole production and detection at the LHC.

Their assumption is that after microscopic black holes form, they would go through four phases:

"First there is the balding phase in which the newly formed back hole evolves from a highly asymmetric object to a more symmetric one, shedding its asymmetry through gravitational radiation.

"In the second phase, called the spin-down phase, the black hole loses mass and angular momentum by emitting Hawking radiation. The third, the Schwarzschild phase, the black hole becomes spherical and the rate of mass loss slows down. And in the final Planck phase, the black hole winks out of existence.

"Of these phases, only the Schwarzschild phase in is understood in any detail mainly because of the symmetry involved. The other phases are poorly understood, particularly the Planck phase which can only be described in terms of quantum gravity, which is itself an untested idea."

The Chandra X-Ray Telescope image at top of page shows a black hole, a disk of hot gas surrounding it and a large doughnut (or torus) of cooler gas and dust enshrouding the system.

Source: The Daily Galaxy - MIT Technology Review and Ref: Micro Black Holes In The Laboratory

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