"The laws of electricity and magnetism that underlie the existence of bulk matter don't care which bits... carry negative charge, and which... are positive. If we swapped all positives to negative, and all negatives to positive... resulting forces would be the same and the structures they built would... be unchanged. ...[T]o all outward appearances, nothing would appear different. Such a swapping of charges would turn what we know as matter into... antimatter. An anti-atom of would consist of a negative encircled by a positively charged . Paul Dirac... first predicted that such a mirror image of matter should exist."