Magnetic monopolies in matter.

Physicists have expended a great deal of effort searching for magnetic monopoles--fundamental particles that have only one magnetic pole. So-called grand unified theories, which mathematically tie together the electromagnetic, weak, and strong forces of nature, predict that magnetic monopoles--if they exist-- would be extremely heavy and move much more slowly than other subatomic particles.

So far, searches for magnetic monopoles have largely focused on their detection among cosmic rays (SN: 10/5/91, p.219), and these efforts have turned up nothing. But a few monopoles, originally created in the early moments of the Big Bang, may have survived and become trapped in matter, particularly the material at the cores of stars.

Now, Hunmoo Jeon and Michael J. Longo of the University of Michigan in Ann Arbor report in the Aug. 21 Physical Review Letters that they have found no evidence of the presence of magnetic monopoles in recycled star matter that's ended up here on Earth. Using a sensitive monopole detector, the researchers examined more than 331 kilograms of material, including iron ores, ferromanganese nodules, and 112 kg of meteorites, before coming to their conclusion.