Questions tagged [virtual-particles]
Use for computational-device notional particles which are not observable in the lab, such as "off-the-mass-shell" particles, "spurions", renormalons, merons. Do *not* use for unobserved hypothetical particles such as the graviton, or Goldstone bosons which could have been observable, but got rearranged into other particles through QFT mechanisms.
547 questions
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How does the virtual photon get its mass?
I recently read that a virtual photon has mass, unlike a real photon. "As a consequence, a real photon is massless and thus has only two polarization states, whereas a virtual one, being ...
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1 answer
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Do Black Holes lead to Oscillating Universe? [closed]
I recently read about the Hawking Radiation. As of what I comprehended is: It is the escape of one of the pair of entangled particles created just at the event horizon from "empty" space. ...
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Question on Quanutm Physics regarding the wave model and paths taken [duplicate]
I was wondering if I am understanding Quantum probabilities are particles correct, so hypothetically if we have a photon and dont know what path it is taking then it will act as a wave, right, and as ...
1 vote
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Why Lamb Shift only applies to bound states? [closed]
If the Lamb Shift of Hydrogen atom is a consequence of the interaction of the bound electron and vacuum energy, why is the same effect not possible with a free electron which also interacts with ...
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Mechanoluminescence of Sound Waves in Air
Basically can we determine a reasonable range of frequencies of photons that serve as the primary carrier of energy in air (so something like STP)? There are some things we know (and questions that ...
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2 answers
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Why "virtual photons" have no defined propagation speed? [closed]
All of our physics QED and QFT in order to comply with conservation laws and the speed of causality c, are based on a so called mathematical constract, fitting parameter, the "virtual photon&...
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How do we account for unstable real particles using Feynman diagrams ($W$, $Z$ boson)?
I have recently been concerned with the production and detection of $W^{\pm}$ and $Z^0$ bosons. As it is well known, the literature is often unclear about virtual/real particles, so let me premise ...
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1 vote
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Polarization states of virtual photon?
I was working through a problem on BhaBha scattering (at tree level), and I am confused about the polarization of the virtual photon. As it is virtual it means that it cannot lie on its mass shell, I ...
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Why do high-energy photons not slow down from virtual interactions?
So my layman's understanding is that a photon with more than around ~1 MeV of energy has a possibility of "acting like" an electron-positron pair in its interactions with other particles. I ...
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2 votes
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Does vacuum energy exist inside non-vacuums? (solids?)
I'm making a follow up version of this question because I agree with the author that [as of] 24 Feb 2022 [...] still not clear on the answer Does "vacuum" energy exist in regions of ...
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Are virtual photons implicated in charge-based attractions and repulsions at all scales or only for fundamental particles?
An answer to this question contains the following thought experiment: "Imagine two people sitting in cars on a frictionless surface throwing snowballs at each other. Every time person A tosses a ...
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1 vote
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Can an infinite universe pop into existence?
I’m thinking about virtual particles and something like a boltzman brain (but an entire infinite universe) popping into existence. Is this even possible? I’ve heard it said somewhere (I think it was ...
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In QFT, what happens when we only integrate over paths inside light cone? [closed]
In the path integral picture of QFT, we have to integrate over all paths connecting two states. What happens when we only integrate over paths that don't violate causality? Since the paths that are ...
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Why can't you have a particle at rest or with no energy?
I've only done an introduction into quantum mechanics but I've seen several videos (This seemed the most credible and confused me the most https://www.youtube.com/watch?v=IRcmqZkGOK4) describing the ...
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1 answer
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Sometimes virtual particles are made out of nowhere but, does the reverse also happen? That a particle disappears and reappears?
According to quantum mechanics, the vacuum is not empty, but teeming with virtual particles that constantly wink in and out of existence. One strange consequence of this sea of activity is the Casimir ...
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