# Quantum fluctuation

According to the quantum fluctuation concept, a particle and its corresponding antiparticle appear out of nothing only to annihilate and emit some energy in the form of electromagnetic waves.

Does this only happen in vacuum? From where do the particles get the energy to come into being in the first place? Does this effect involve only electrons and quarks (and thus positrons and antiquarks) or protons and neutrons too?

• This might help. Note also that you'll never find free quarks. – Kyle Kanos Dec 16 '14 at 21:51
• Real particles do not appear out of nowhere. They only appear if there is enough energy available to create a real particle-antiparticle pair, and even then it usually requires a mediating field from a charged massive particle to make that process likely. Spontaneous $\gamma\gamma \to x\bar{x}$ has an exceedingly small cross section for currently available photon energies and fluxes. In short, the meaning of fluctuations in quantum field theory is usually very poorly explained to and understood by non-physicists. – CuriousOne Dec 17 '14 at 2:33
• @KyleKanos: Why there are no free quarks? They are not virtual particles, are they? Then, what's the reason? You recommended a site, but I don't see there a motivation, I see sending to further and further sites. – Sofia Dec 18 '14 at 20:32
• @Sofia: I think JohnRennie's answer is fine enough for explaining it, but perhaps the Wikipedia page on Color confinement might prove better? – Kyle Kanos Dec 18 '14 at 20:37
• also this answer may help in understanding physics.stackexchange.com/questions/209327/… – anna v Sep 29 '15 at 18:30