Particles and antiparticles

• electromagnetic radiation exists as photons of energy - the energy of a photon depends on the frequency of the radiation, using formula e=hf. a photon is a massless discrete packet of electromagnetic energy.
• each particle has a matching antiparticle with the same mass and rest energy, but with opposite charge
• einsteins theory of relativity says that energy can turn into mass and mass can turn into energy. when energy is converted into mass, you get equal amounts of matter and antimatter. the rest energy of a particle is the 'energy equivalent' of the particles mass, measured in MeV.