The process where a particle and its antiparticle collide and convert their mass into energy.Annihilation is the process where a particle and its corresponding antiparticle collide and convert their entire rest mass into energy, typically in the form of photons or other particles. This is the most efficient energy conversion known, releasing energy according to Einstein's equation E=mc². Annihilation is a key process in particle physics, astrophysics, and cosmology, explaining phenomena from cosmic gamma-ray bursts to the matter-antimatter asymmetry in the universe.
The concept of antiparticles was predicted by Paul Dirac in 1928, and the positron was discovered by Carl Anderson in 1932. The term 'annihilation' was coined shortly after, and the process has been studied extensively in particle accelerators and cosmic ray observations.
When a particle meets its antiparticle, they annihilate, producing a burst of energy. For example, an electron and a positron can annihilate to produce two gamma-ray photons. The energy and momentum of the initial particles are conserved, so the resulting photons carry away the total energy. In some cases, annihilation can also produce heavier particles, like quarks, if the energy is sufficient.
Annihilation is used in positron emission tomography (PET) scans, where positrons annihilate with electrons in the body, producing gamma rays that are detected to create medical images.
The annihilation of matter and antimatter in the early universe is thought to have left a tiny excess of matter, which is why the universe is made of matter today rather than being empty.
No articles yet