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If virtual particles cancel out after being created from spacetime flunctuations because they come in matter-antimatter pairs, how do virtual photons cancel out, due to a photon being its own antiparticle?

Abdul Moiz Qureshi
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    Virtual particles are more of a calculational tool than a particle that actually exists and can be observed. This is why they don't have to conform to some of the rules that real, observable particles do. – probably_someone Nov 19 '18 at 12:09
  • virtual photons can be interpreted as external legs that die off if they don't encounter an asymptotic on-shell particle to merge with, when there is an encounter their energy exchange is consistent with the asymptotic behavior of the on-shell components – lurscher Nov 19 '18 at 12:13
  • Also Energy conservation of Virtual Particles - Quantum Fluctuation? – John Rennie Nov 19 '18 at 12:16
  • Also Why do many people say that virtual particles do not conserve energy? – John Rennie Nov 19 '18 at 12:17
  • @John Rennie, two things differentiate my question from those three. First, the question is specifically about photons. Second, photons do not have antiparticles, so they cannot annihilate.-------- as an aside, do you know why I've lost a single reputation point despite not downvoting any answer? – Abdul Moiz Qureshi Nov 19 '18 at 12:48
  • Hi Abdul. If you look at your rep history you'll see you have received three downvotes (not from me!) and one upvote on this question. So that's -6 on downvotes and +5 on upvotes giving a net change of -1. – John Rennie Nov 19 '18 at 12:54
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    Re the proposed duplicates: the point made in all three questions is that virtual particles are not physically real - they are a computational device and they do not actually exist. Let me emphasise this: virtual particles do not exist. So the question of how they appear and disappear is meaningless since they don't appear and disappear. – John Rennie Nov 19 '18 at 12:56
  • Is there any other example in physics of a computational device in equations that does not actually exist? Also, exactly what purpose do virtual particles have (in layman's terms). – Abdul Moiz Qureshi Nov 19 '18 at 14:02
  • I feel like it would be more accurate to say that virtual particles are not 'particles' than that they 'do not exist'. You should really not think of 'virtual particles' as tiny balls happily flying around in free space like real particles do. In that sense the terminology is very confusing and could easily lead to unwarranted speculation, especially among popular science writers. Rather, 'virtual particles' are the quantum equivalents of the classical EM field around any charged object: they are the things that mediate interactions between charged particles. – Stijn B. Nov 19 '18 at 15:45
  • Since you believe that they exist, how do they cancel out when they can't annihilate? – Abdul Moiz Qureshi Nov 19 '18 at 16:31
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    @AbdulMoizQureshi There's at least one other example of a computational device in physics that doesn't actually exist: the ideal "wires" that are drawn in circuit diagrams. They do not correspond to any actual physical object; rather, they are there to demonstrate the way in which the other (real) components are connected together. This is why they can have properties that would be strange for any real object to have (for example, having no voltage drop across them, and no resistance, but also carrying finite current). – probably_someone Nov 19 '18 at 21:00
  • Also, for the record, I think John Rennie and Stijn B. are reasoning based on different definitions of the word "exist," so you shouldn't try to apply half of John Rennie's argument to Stijn B.'s reasoning. – probably_someone Nov 19 '18 at 21:04
  • @probably_someone, I wasn't applying any of John Rennie's argument. I was asking probably_someone to answer according to the premise set by the original question. If virtual photons exist, and conservation of energy is preserved because the virtual particles come in matter-antimatter pairs, then how can photons annihilate since they don't have any antiparticles. – Abdul Moiz Qureshi Nov 20 '18 at 06:00

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