I've looked everywhere I can think, this side of paywalls, and everyone provides Feynman diagrams or $E=mc^2$ to describe or calculate annihilation. It occurred to me that virtual particles come into existence and annihilate each other all the time.

I'm trying to understand this disconnect. Does virtual particle creation cause "anti-energy" that counters the energy released during annihilation?

Has anyone actually measured the energy output of a proton/antiproton collision? I couldn't find a record of any such experiment. It's all theoretical calculations. All of my search results are cluttered by "gravity works on antimatter!" announcements.

  • $\begingroup$ I'm far from an expert on this topic but I'm not sure how literally the creation/annihilation of matter/antimatter particles as quantum fluctuations are commonly described should be taken. $\endgroup$
    – jng224
    Commented May 5 at 18:16
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    $\begingroup$ Virtual particles are a mathematical fiction; they aren't real particles. From physics.stackexchange.com/a/185139/123208 "virtual particles exist only in the mathematics of the model used to describe the measurements of real particles". Also see physics.stackexchange.com/q/147096/123208 & physics.stackexchange.com/a/275099/123208 & links therein. $\endgroup$
    – PM 2Ring
    Commented May 5 at 18:32
  • $\begingroup$ Proton / antiproton collision is a messy process, with a variety of possible outcomes, and the complexity increases as the collision energy increases. I have some info on that (and a few other annihilation reactions) here: physics.stackexchange.com/a/451337/123208 $\endgroup$
    – PM 2Ring
    Commented May 5 at 18:57
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    $\begingroup$ Since the purpose of LEP was to collide electrons and positrons, I would assume that they made trillions of measurements of what the annihilation of these particles produced. $\endgroup$
    – Ghoster
    Commented May 5 at 22:10
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    $\begingroup$ @RobertRapplean Virtual particles are a convenient calculation tool. But they don't have much to do with the Casimir effect. physics.stackexchange.com/a/349743/123208 They can be used to explain Hawking radiation, but that's just a heuristic picture, and Hawking himself advised against taking it too seriously. physics.stackexchange.com/a/761625/123208 $\endgroup$
    – PM 2Ring
    Commented May 6 at 3:04

1 Answer 1


I'm not sure if this answers your question, but Positron Emission Tomography (PET) is a standard type of medical imaging and uses a matter-antimatter annihilation process - namely electrons and positrons annihilate producing gamma rays. Some details below: (Referencing Wikipedia)

"The most significant fraction of electron–positron annihilations results in two 511 keV gamma photons being emitted at almost 180 degrees to each other."

(Source: https://en.wikipedia.org/wiki/Positron_emission_tomography)


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