From antimatter to mirror matter

The idea of a 'mirror world' was first suggested in 1956 by Chinese-American physicists Chen Ning Yang and Tsung Dao Lee. First, a tiny dose of particle physics, before you can enter their 'mirror world'. The universe is held together by four types of fundamental forces - gravity, electromagnetism, the strong force, and the weak force - which are transmitted or 'mediated' by the exchange of elementary particles. The gravitational force, or gravity, is the long-range force responsible for the...