Monday, 30 January 2017
Not long after Schrodinger developed his famous equation in the 1920s, Paul Dirac made a more accurate version that included the recently discovered principles of relativity. Dirac’s version of Schrodinger’s equation predicted the existence of particles that were a mirror image of electrons, and that if one of these particles and an electron were to come into contact they would destroy each other.
At the time physicists thought this proved there was something wrong with Dirac’s equation, but in 1932 Carl Anderson discovered these ‘anti-electrons’ in experiments with ‘cosmic rays’- high energy photons that arrive at the earth from the Sun.
Since then, quantum theory has developed to suggest that every type of particle has a corresponding anti-particle, and physicists have managed to combine anti-electrons with anti-protons and anti-neutrons to form anti-atoms of anti-elements. It seems that the particles of anti-matter behave in exactly the same way as ordinary matter, except that matter and anti-matter annihilate each other.
When a particle and an anti-particle interact, they vanish, and their mass is converted into pure energy (in the form of very energetic photons). The exchange rate between mass and energy is huge- about a hundred thousand million million- so when even a tiny amount of mass is destroyed a huge amount of energy is released.
One of the many big mysteries in physics is why the universe seems to be made almost entirely of matter, with hardly any anti-matter.