Published online 2 October 2001 | Nature | doi:10.1038/news011004-8


CERN to spew black holes

Mini black holes could reveal hidden dimensions of space.

Line showing scale of CERN's 27 kilometer colliderLine showing scale of CERN's 27 kilometer collider© CERN

Physicists at may soon be manufacturing copious quantities of black holes. When the Large Hadron Collider (LHC) at CERN, the European particle physics laboratory near Geneva, is completed in 2005, it could produce a black hole every second.

These tiny, fleeting phenomena might just give researchers a long-sought glimpse of the hidden dimensions of space.

In the 27-kilometre-long circular tunnel that held its predecessor, the LHC will be the most powerful particle accelerator in the world. It will smash fundamental particles into one another at energies like those of the first trillionth of a second after the Big Bang, when the temperature of the Universe was about ten thousand trillion degrees Centigrade.

At such extreme energies, physicists hope that matter will begin to give up some of its deepest secrets, such as how it acquires mass and how gravity arises from quantum mechanics.

And these high-energy events will generate vast numbers of minuscule black holes, Savas Dimopoulos of Stanford University in California and Greg Landsberg at Brown University in Providence, Rhode Island now calculate1.

Black holes are the dark and massive pirates of interstellar space. They form when burnt-out stars collapse under their own gravity, squeezing immense mass into negligibly small space and creating huge gravitational fields that suck in everything that passes nearby -including light.

Because the LHC will cram vast amounts of energy into tiny volumes, this too should form black holes. These will be about a million times smaller than the nucleus of an atom and will survive for barely an instant.

The physicist Stephen Hawking predicted in the 1970s that black holes would evaporate by radiating away their energy. For astrophysical black holes this is a very slow process, but extremely small black holes should last about as long as a snowflake in hell.

The radiation from evaporating black holes in LHC experiments should signal their brief existence, say Dimopoulos and Landsberg. This would also confirm Hawking's prediction, which has never yet been put to the test. Even more intriguingly, this 'Hawking radiation' might hold clues about the fabric of space itself.

Most theories of the earliest instants of the Universe's life agree that space-time has more dimensions than the four (three of space, one of time) we normally experience. No one is sure quite how many extra dimensions are required - they are 'felt' only during very energetic processes, such as the formation of mini black holes.

The relationship between the temperature of a black hole, the intensity of its Hawking radiation and its mass depends on the number of extra dimensions. So by studying this radiation in the LHC, physicists may finally count the hidden dimensions of space. Physicists Steve Giddings and Scott Thomas in California have reached the same conclusions about CERN's impending ability to manufacture black holes2. 

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