In some
science fiction
Science fiction (sometimes shortened to Sci-Fi or SF) is a genre of speculative fiction which typically deals with imaginative and futuristic concepts such as advanced science and technology, space exploration, time travel, parallel unive ...
stories, total conversion may mean higher or complete conversion of matter into energy, or vice versa in some proportion of
''E = mc2''.
Energy to matter conversion
Positron
The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. It has an electric charge of +1 '' e'', a spin of 1/2 (the same as the electron), and the same mass as an electron. When a positron collides ...
and
electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have no kn ...
production: For
photon
A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless, so they always ...
s at high-energy (
MeV
In physics, an electronvolt (symbol eV, also written electron-volt and electron volt) is the measure of an amount of kinetic energy gained by a single electron accelerating from rest through an electric potential difference of one volt in vacu ...
scale and higher), photon–photon collisions can efficiently convert the photon energy into matter in the form of a positron and an electron:
+ → +
Proton
A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...
and
antiproton
The antiproton, , (pronounced ''p-bar'') is the antiparticle of the proton. Antiprotons are stable, but they are typically short-lived, since any collision with a proton will cause both particles to be annihilated in a burst of energy.
The exis ...
production: Conventional matter consists of protons and electrons, with electrons having insignificant mass compared to protons. One conventional model for producing protons from energy is extremely high-energy cosmic ray protons colliding with nuclei in the interstellar medium, via the reaction: + A → + + + A. (A represents an atom, p a proton, and an antiproton.) A portion of the kinetic energy of the initial proton is used to create two additional nuclei: another proton plus an antiproton.
Matter to energy conversion
Conventional nuclear reactions such as
nuclear fission
Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radio ...
and
nuclear fusion
Nuclear fusion is a reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic particles ( neutrons or protons). The difference in mass between the reactants and products is manifest ...
convert relatively small amounts of matter only indirectly into useful energy, such as electricity or rocket thrust. For electricity production released nuclear energy in the form of heat is typically used to boil water to turn a turbine-generator.
Possibly matter is almost completely converted into energy in the cores of
neutron star
A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially metal-rich. Except for black holes and some hypothetical objects (e.g. white ...
s and
black holes
A black hole is a region of spacetime where gravity is so strong that nothing, including light or other electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts that a sufficiently compact mass can def ...
by a process of nuclei collapse resulting in: proton → positron + 938 MeV, resulting in a >450 MeV positron-electron jet. Trace nuclei swept up in such a beam would achieve an approximate energy of (nucleus mass/electron mass) × 450 MeV, for example an iron atom could achieve about 45 TeV. An up to 45 TeV atom impacting a proton in the interstellar medium should result in the p + A process described above.
Ion
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...
-electron or positron-electron plasma with magnetic confinement theoretically allows direct conversion of particle energy to electricity by the separation of the positive particles from the negative particles with magnetic deflection. Direct conversion of particle energy to thrust is theoretically simpler, merely requiring magnetically directing a neutral plasma beam. Present lab production of relativistic 5 MeV positron-electron beams mimic on a small scale the relativistic jets from compact stars, and allow small scale studies how different elements interact with 5 MeV positron-electron beams, how energy is transferred to particles, the shock effect of
gamma-ray bursts
In gamma-ray astronomy, gamma-ray bursts (GRBs) are immensely energetic explosions that have been observed in distant galaxies. They are the most energetic and luminous electromagnetic events since the Big Bang. Bursts can last from ten millise ...
, and possible direct thrust and electricity generation from neutral plasmas. Lab positron-electron plasmas could be useful for studying compact star jets and other phenomena. However thrust generation or magnetically separating neutral beams for electrical generation will probably only be useful if there is a practical continuous process for generating neutral plasma by nuclear reactions.
Lab production of 5MeV positron-electron beams
/ref>
References
Science fiction themes
Fictional technology
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