Mini Black Hole

Mini Black Hole 

by : Aria Ratmandanu 

       Normally, we expect quantum effects from gravity to occur at the Planck energy, which is a quadrillion times more powerful than our most powerful particle accelerator, making direct tests of string theory impossible. But if there really is a parallel universe that exists less than a millimeter from ours, then the energy at which unification and quantum effects occur may be quite low, within reach of the next generation of particle accelerators, such as the Large Hadron Collider (LHC). This, in turn, has sparked an avalanche of interest in black hole physics, the most exciting being the “mini–black hole.” Mini–black holes, which act as if they are subatomic particles, are a “laboratory” in which one can test some of the predictions of string theory. Physicists are excited about the possibility of creating them with the LHC. (Mini–black holes are so small, comparable to an electron in size, that there is no threat that they will swallow up Earth. Cosmic rays routinely hit Earth with energies exceeding these mini–black holes, with no ill effect on the planet.)

          As revolutionary as it may seem, a black hole masquerading as a subatomic particle is actually an old idea, first introduced by Einstein in 1935. In Einstein’s view, there must be a unified field theory in which matter, made of subatomic particles, could be viewed as some sort of distortion in the fabric of space-time. To him, subatomic particles like the electron were actually “kinks” or wormholes in curved space that, from a distance, looked like a particle. Einstein, with Nathan Rosen, toyed with the idea that an electron may actually be a mini–black hole in disguise. In his way, he tried to incorporate matter into this unified field theory, which would reduce subatomic particles to pure geometry.

        Mini–black holes were introduced again by Stephen Hawking, who proved that black holes must evaporate and emit a faint glow of energy. Over many eons, a black hole would emit so much energy that it would gradually shrink, eventually becoming the size of a subatomic particle.

        String theory is now reintroducing the concept of mini–black holes. Recall that black holes form when a large amount of matter is compressed to within its Schwarzschild radius. Because mass and energy can be converted into each other, black holes can also be created by compressing energy. There is considerable interest in whether the LHC may be able to produce mini–black holes among the debris created by smashing two protons together at 14 trillion electron volts of energy. These black holes would be very tiny, weighing perhaps only a thousand times the mass of an electron, and last for only 10-23 seconds. But they would be clearly visible among the tracks of subatomic particles created by the LHC.

      Physicists also hope that cosmic rays from outer space may contain mini–black holes. The Pierre Auger Cosmic Ray Observatory in Argentina is so sensitive that it can detect some of the largest bursts of cosmic rays ever recorded by science. The hope is that mini–black holes may be found naturally among cosmic rays, which would create a characteristic shower of radiation when they hit Earth’s upper atmosphere. One calculation shows that the Auger Cosmic Ray de- tector might be able to see up to ten cosmic ray showers per year trig- gered by a mini–black hole.

        The detection of a mini–black hole either at the LHC in Switzerland or the Auger Cosmic Ray detector in Argentina, perhaps within this decade, would provide perhaps good evidence for the ex- istence of parallel universes. Although it would not conclusively prove the correctness of string theory, it would convince the entire physics community that string theory is consistent with all experimental results and is in the right direction.