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Asaf Pe'er

Asaf Pe'er

## What is anti-matter? |

Antiparticles were first predicted in 1928, by the British physicist Paul Dirac. Dirac was one of the pioneers of quantum field theory- the theory that combines quantum mechanics with Einstein's special theory of relativity. Dirac was looking for an equation that would describe the properties of an electron, moving at relativistic speed. He managed to write such an equation, which won him the Nobel Prize in 1933. When looking at this equation, he found something strange. Just as the equation x

Anti-particles have all the properties of particles: elementary anti-particles can form anti-atoms, anti-molecules, and as far as we know, there could be entire galaxies and universes made of anti-matter.

However, when an anti-particle collides with a particle, they both annihilate - giving rise to variable proportions of intense photons (gamma rays), neutrinos, and less massive particle-antiparticle pairs. The total consequence of annihilation is a release of energy available for work, proportional to the total matter and antimatter mass, in accord with the mass-energy equivalence equation, E = mc

Thus, in fact, one of the greatest mysteries of modern physics today, is why the universe that we see is filled with particles, rather than equal amount of particles and anti-particles? The process by which this inequality between particles and antiparticles developed, which much have occurred very close to the big-bang is called baryogenesis.

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