This is more of a statement than a question but I am bothered by the fact that to explain certain things, virtual particles are required. By definition these don't exist, yet they are used to explain things that do exist - a possible conundrum or maybe circular reasoning? Is anyone else bothered by this? We are dealing in the smallest of scales, but as computing power and optics and all other technologies increase, maybe we will be able to come up with some concrete answers.
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1$\begingroup$ One also uses pseudo forces to explain things in in classical mechanics. Does that bother you too? Or is this about selective botherism? $\endgroup$– OбжорoвCommented Feb 12, 2021 at 13:34
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4$\begingroup$ It is neither a crutch nor handwaving. It seems you have misunderstood what virtual particles are, but that is likely a relic of the unfortunate terminology that is "virtual particles". They are, as you say, not real, and are only really as a calculational device in perturbative calculations. Do not be misled by the terminology, they only arise out of the methodology that we use to calculate amplitudes, and so there is no conundrum of any sort. $\endgroup$– Nihar KarveCommented Feb 12, 2021 at 14:13
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1$\begingroup$ You use complex numbers in electromagnetism all the time to describe very real fields; that should not bother you, either. Mathematical techniques to solve equations describing reality, which "virtual particles" are ( codeword for suitable propagators in perturbative QFT), should make you comfortable and curious to learn more form a text, not "just saying" posts. $\endgroup$– Cosmas ZachosCommented Feb 12, 2021 at 14:39
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1$\begingroup$ Possible duplicate of physics.stackexchange.com/q/147096 and physics.stackexchange.com/q/109229 $\endgroup$– Nihar KarveCommented Feb 12, 2021 at 15:01
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2$\begingroup$ "it is true that there has been no real developments in this field in over 40 years (see Lost In Math) so something is seriously wrong (meaning misunderstood)." Seriously? $\endgroup$– OбжорoвCommented Feb 12, 2021 at 17:53
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2 Answers
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Virtual particles are better regarded as a convenient way of representing terms in the infinite sums of quantum field theory than as particles. Feynman introduced his diagrams to organise the calculations but did not claim the virtual particles were "real" in any useful sense.
They are not ontological explanations for things, but often used in popular explanations since the full answer requires a lot of math most listeners are not ready for/interested in.
answered Feb 12, 2021 at 14:51
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Look at it this way:
It is the present day mathematical model of nature in the microcosm.
Particles are quantum mechanical entities on which quantum numbers are absolutely attached , and a four vector $(E,p_x,p_y,p_z)$. If that four vector's length is fixed, it is called the invariant mass of the particle. If the length is variable within a mathematical integration, the entity is called virtual.
If, or when, we have a complete quantum mechanical theory for the universe, it would mean that one wavefunction should describe everything, and then all particle entities would be virtual, and what we call now real would need a measure, like the heisenberg uncertainty, to decide how much off mass shell the observed particles, say the electrons, could be in order to be treated as what at present we call real.
