Matter creation is process inverse to annihilation. It usually refers to pair creation, i.e., the conversion of photons into a fermion and antifermion pair, such as an electron and a positron. Since momentum conservation law prohibits the creation of a pair of fermions out of a single photon, pair creation involves at least two photons (or a single photon and one or more fermions). This, in turn, requires a high photon density to create a noticeable amount of matter. Annihilation occurs when a particle collides with an antiparticle. ... In physics, the photon (from Greek φοτος, meaning light) is a quantum of excitation of the quantised electromagnetic field and is one of the elementary particles studied by quantum electrodynamics (QED) which is the oldest part of the Standard Model of particle physics. ... Fermions, named after Enrico Fermi, are particles which form totally-antisymmetric composite quantum states. ... Fermions, named after Enrico Fermi, are particles which form totally-antisymmetric composite quantum states. ...
Energy conservation law provides a lower limit for the photon energy required for creation of a pair of fermions. It must not be less than the rest energy of the fermions created. For example, to create an electron-positron pair (2mc2 = 1.04 MeV), the total energy of the photons must be greater than or equal to 1.04 MeV, corresponding to soft gamma ray photons. As another example, the creation of a proton-antiproton pair requires more than 1.88 GeV (hard gamma ray photons). Thus, to precipitate matter, a photon gas must not only be very dense but also very hot. The rest energy of a particle is its energy when it is not moving relative to a given inertial reference frame. ... This article is about electromagnetic radiation. ...
Matter creation during the early development of the universe (see Big Bang) is believed to be the source of fermionic matter in the visible universe, which consists predominantly of electrons and protons. According to the Big Bang theory, the universe originated in an extremely dense and hot state (bottom). ...
According to the theory of relativity there is no distinction between matter and energy, because matter can be converted to energy (see annihilation), and vice versa (see mattercreation).
In chemistry, matter is often restricted to chemical substances, as elementary particles such as quarks and leptons are not known to participate in chemical reactions.
matter that is composed of the antiparticles of those that constitute normal matter.
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