We all know that every substance is made up of particles. Those particles may be electron, proton and neutron in different terms. The small constituents that possess the mass and has a chare and the spin is the perfect definition for particles. There is antiparticles as well. Antiparticles are those which have the same mass as that of the particles but have opposite charge and the spin. In this way we can distinguish between particles and antiparticles but besides these there are many neutral or massless particles. Photon is the particle that has...