January 25, 2016
If a particle meets an anti-particle, they cancel out each other and vanish without a trace, a process called mutual annihilation. In the course of the annihilation, higher energy photons, called gamma rays, are released with energy exactly equivalent to the mass before the annihilation. In 1949, Richard Feynman (1918-1988), in his diagram of particle-antiparticle annihilation, shows that when an electron meets an anti-electron (positron), two photons are created out of nowhere at the point of contact; these two photons depart in opposite directions at the speed of light. Photons are said to be mass-less and does not have electric charge. The proton, the electron, the photon, and the neutrino are considered stable particles, in the sense that they live forever, but can be annihilated when they are involved in a collision. The neutron can fall into pieces spontaneously in a process of disintegration called “beta decay.” The process transforms the neutron into a proton, accompanied by the creation of an electron and a new mass-less particle called neutrino.
All the other particles (at least those discovered until the mid-1970s, except for the proton, electron, photon, and neutrino) are considered unstable, since they undergo a process of decay almost immediately after they are created. These unstable particles disappear after a few “particle second” and although they are invisible, they leave their tracks in the bubble chamber. In the collision process, only those stable particles remain. Clearly, at the moment of collision, an annihilation-creation process immediately commences, where the colliding particles themselves annihilate each other and vanished into nothingness and the highly focused energy emitted from these two colliding particles literally create new particles whose existence and properties can be detected through the tracks they leave behind at the collision point.
For example, using huge particle accelerators, in a collision between a proton and an antiproton, it can be seen that while the initial colliding particles are completely annihilated, the collision process also gives way to the creation of new particles, called pions. Incredible as it may seem, the collision tracks can be photographed (the photographs are reproduced in Capra, 1975:187, 217-225). In another particle collision between a pion and a proton, photographs show 16 particles created. It is also found out that newly created particles undergo further collisions or decay, thus, the continuing process of annihilation and creation. This event is likened to the Big Bang, a cataclysmic explosion that marks the creation of the Cosmos.