(1) Positively charged beta particles, the antiparticle of electrons, are called positrons.(2) Note that subatomic particles sometimes have antiparticles , with opposite charge and spin, that are the same ones going backwards in time.(3) At about one second into the life of the universe, the majority of existing particles and antiparticles had been destroyed to produce photons of electromagnetic radiation.(4) Some neutral particles such as photons are their own antiparticles, while others like neutrons have antiparticles with opposite magnetic moments.(5) One can imagine atoms that are made of antiparticles : antiprotons, antineutrons, and positrons.
