Is there some reverse of annihilation?

[Stanley514]

When heavy nuclei split up we get energy,when light nuclei join together we get energy.
When elemental particles split up in annihilation we get energy (photons).
What if we join certain photons together?Could we obtain energy in this way and make analog of
nuclear fusion?

 

[fluidistic]

When heavy nuclei split up we get energy,when light nuclei join together we get energy.
When elemental particles split up in annihilation we get energy (photons).
What if we join certain photons together?Could we obtain energy in this way and make analog of
nuclear fusion?

Yes. See http://en.wikipedia.org/wiki/Matter_creation.

 

[Pythagorean]

See 'pair production'.

a large enough electric field applied to a vacuum will create positron-electron pairs.

 

[Stanley514]

I also mean something that could generate net energy similar to fusion and be used by humans.

 

[Bob S]

When heavy nuclei split up we get energy,when light nuclei join together we get energy.
When elemental particles split up in annihilation we get energy (photons).
What if we join certain photons together?Could we obtain energy in this way and make analog of nuclear fusion?

When heavy nuclei split up, the resulting masses are less, and the mass difference is converted to energy (photons, heat). The remaining mass is the minimum mass subject to constraints (e.g., baryon number).

In fusion reactions, the resulting masses are less, and the mass difference is converted to energy (photons, heat). The remaining mass is the minimum mass subject to constraints.

When two photons produce particles (e.g., baryon anti-baryon pair) the anti-baryon quickly annihilates with a baryon (not the same one), and the baryon count remains zero, with no net energy released.

[added] Beta decay will often occur immediately after these processes, and (anti)-neutrinos will then carry off some un-recoverable energy.

Bob S

 

[Stanley514]

Beta decay will often occur immediately after these processes, and (anti)-neutrinos will then carry off some un-recoverable energy.

Could you give some link to more detailed info in this subject?
Beta decay from where is happening?Does it mean that energy conservation law is violated?

There is also such technique as frequency doubling when one two photons combine to form one with greater energy.
Do such combinations or maybe spliting generate some net energy?Or they always loose it?

 

[Bob S]

Although beta decay is not directly part of nuclear fission, the beta-day lifetimes are sometimes so short that the additional beta-decay energy released can be counted as part of the total energy release in the total fission fragmentation process. There are many neutron-rich fission products with half-lives in the millisecond range.

When I referred to (anti) neutrinos carrying away "un-recoverable" energy, I did not mean that the energy is lost. The neutrinos end up in some other galaxy in a few thousand light-years, and release their energy there, but the energy is never really "lost". Energy is always conserved in some form, of which the lowest forms (when there are no constraints) are photons or phonons; gammas, X-rays. UV, light, IR, etc. With one exception (that I can think of), neutrinos are always released in a continuous spectrum up to a fixed-energy end point (Curie point), and never in a discrete energy line, like the 661-KeV Cs-137 gamma ray line for example.

When two equal-energy photons collide and create a matter-antimatter pair, the energy of the two photons adds to produce E_CM, or total energy in the center of mass. But the two photons do not literally couple to produce a single photon of twice the energy (e.g., "frequency doubling", like in lasers). Look up two-photon physics.

http://en.wikipedia.org/wiki/Two-photon_physics

Bob S

 

[Stanley514]

Is it possible to stimulate beta decay of isotopes with very strong electrical fields?
There is lot of isotopes in Earth crust,for example zinc-70 or Ptassium-40 which have very long beta decay half life.If we could stimulate very short half-life in them we could create clean neutroneless energetics.
http://prc.aps.org/abstract/PRC/v29/i5/p1825_1