magnetic monopoles

Magnetic monopoles are hypothetical particles with single magnetic charge, either a north pole or a south pole. Some speculative theories suggest that, if they exist, magnetic monopoles could cause protons to decay. These theories also say that such monopoles would be too heavy to be produced at the LHC. Nevertheless, if the magnetic monopoles were light enough to appear at the LHC, Cosmic rays striking the Earth's atmosphere would already be making them, and the Earth would very effectively stop and trap them. The continued existence of the Earth and other astronomical bodies therefore rules out dangerous proton-eating magnetic monopoles light enough to be produced at the LHC.