Annihilation
Annihilation occurs when a particle collides with an antiparticle. It transforms mass into energy of some form. The energy is carried by force carriers, particles that can decay into other particles. It means that, contrary to a popular belief, the annihilation produces more than just photons. What is produced depends on the particles and antiparticles involved.
When an electron annihilates a positron (anti-electron) the process yields pure energy in a form of gamma rays, see Electron-positron annihilation. When a proton annihilates an antiproton they produce gamma rays and a swarm of secondary particles, like pairs of top-anti-top quarks. The secondary particles will eventually decay into neutrinos and low-energy gamma rays. Knowing that neutrinos could hold some mass, it could mean that the annihilation doesn't transform all the mass into energy.
Annihilation is the most powerful reaction in the universe, and is one of the few ways matter can be converted into energy. Scientist think that annihilation was the reason there is empty space in the universe. The theorized that all the space in the universe was filled with matter and anti-matter, until they annihilated each other, creating energy and creating a vacuum in the space they had once filled.
For other meanings see: laws of logic, annihilation operator.
