Mirror matter: Meaning (information, definition, explanation, facts)

In physics, mirror matter is a hypothetical form of dark matter.

The concept of mirror matter was first introduced by Lee and Yang in 1956, when it was discovered that Nature seems to violates P-symmetry. It is postulated that every particle has a mirror partner. Mirror particles interact amongst themselves in the same way as ordinary particles, with the exception that P-symmetry is broken in exactly the opposite way.