Virtual Particles: Questions & Answers

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Discussion Overview

The discussion revolves around virtual particles, exploring their nature, potential effects, and implications in various contexts such as gravitational forces and dark matter. Participants pose questions and share insights related to theoretical aspects, experimental observations, and conceptual clarifications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants inquire about the types of particles that form virtual particle pairs in a vacuum and whether these particles can exert gravitational forces during their brief existence.
  • One participant explains that virtual particles arise from the combination of special relativity and quantum mechanics, suggesting they help transmit forces but are momentary and thus undetectable in terms of gravitational effects.
  • A question is raised regarding the concept of negative energy associated with virtual particle pairs, particularly in relation to an experiment involving two plates in a vacuum.
  • Another participant argues that the collective gravitational effects of numerous virtual particles could be significant, questioning the assertion that their effects are negligible.
  • Several participants express interest in the potential connection between virtual particles and dark matter, with some stating that while virtual particles cannot account for dark matter, others propose that they might be a candidate.
  • Requests for resources on the density of virtual particle creation are made, with references to specific literature provided by participants.
  • One participant elaborates on the implications of virtual particles on the energy loss of photons traveling through space, linking this to redshift and cosmic expansion.

Areas of Agreement / Disagreement

Participants generally express differing views on the gravitational effects of virtual particles and their potential role in dark matter, indicating that multiple competing perspectives exist without a clear consensus.

Contextual Notes

There are unresolved questions regarding the definitions and implications of virtual particles, particularly concerning their gravitational effects and their relationship to dark matter. Some claims rely on specific theoretical frameworks that may not be universally accepted.

Who May Find This Useful

This discussion may be of interest to those studying quantum field theory, gravitational physics, and cosmology, as well as individuals curious about the theoretical implications of virtual particles in modern physics.

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I've got a few questions about virtual particles here. If in a vacuum, the virtual particle come in a particle, anti-particle pair. What are these particles usually? Also, is it possible that these virtual particles exert a gravitational force on an object during its short existence?? And finally, can virtual particles be used to account for the dark matter in our universe?
 
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It is a result of combining special relativity with quantum mechanics that all particles have an identical one with certain properties (that are negative of the original) called anti-particles. The electron's antiparticle is the positron, photon's antiparticle is another photon and so on.

In the presence of a field (there is a field everywhere) there is a probability that particle- anti-particle pairs will come into existence. These particles help to transmit "the force" of the field. These particles also will have gravitational effects, but their existence is so momentary that no discernible effects of them can ever be measured. That's why they are called virtual particles.

They cannot account for dark matter, since their existence cannot be verified, but other effects of their existence can be verified. That's why we know they do exist.
 
Is negative energy created when a virtual particle pair is created? I ask this because I remember an experiment where two plates separated in a vacuum are pushed together by the "negative" energy between them due to the differential in virtual particles. Is this negative energy there because it counteracts the positive energy of the virtual particles?
 
But won't the gravitational effects virtual particles in a vacuum be apparent since we're not just talking about the gravitational effect of one virtual particle alone. If there are a hell lot of virtual particles popping in and out at the same time, won't there be a noticeable gravitational effect?

And also, if the existence of virtual particles are verified, can they be used to account for dark matter?
 
Is there anywhere I can find out about the 'density' of virtual particle creation?
 
https://www.physicsforums.com/journal.php?s=&action=view&journalid=13790&perpage=10&page=2

Scroll down to the 'what are virtual particles' entry

marlon
 
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Ah! so as light travels through the 'vacuum' of space it will be impinge upon these virtual particles and loose energy to them. Any two photons will loose almost exactly the same amount of energy over large distances. This will appear as red shift. As the photons wavelengths grow the volume of space they occupy will grow and so they will loose energy at an increases rate - giving the impression of
1) the expansion of space
2) the acceleration of the expansion of space
3) given that shorter wavelengths are less affected, brighter than expected gamma ray bursts!
4) I'm not sure how the virtual particle recombination is affected but it could lead to a constant backgound radiation.

Now wheres my calculator...
 
masudr said:
It is a result of combining special relativity with quantum mechanics that all particles have an identical one with certain properties (that are negative of the original) called anti-particles. The electron's antiparticle is the positron, photon's antiparticle is another photon and so on.

In the presence of a field (there is a field everywhere) there is a probability that particle- anti-particle pairs will come into existence. These particles help to transmit "the force" of the field. These particles also will have gravitational effects, but their existence is so momentary that no discernible effects of them can ever be measured. That's why they are called virtual particles.

They cannot account for dark matter, since their existence cannot be verified, but other effects of their existence can be verified. That's why we know they do exist.

What is written here really is not the best of impressions of what virtual particles really are and how they arise in QFT. Besides, the fact that virtual particles can be a candidate for dark matter is indeed proposed by some scientists and denied by others. Rather then repeating myself ad nauseum, i refer to my journal for info on both virtual particles and the articles on virtual particles and their 'connection' to dark matter and dark energy

marlon
 
Tom Potts said:
Is there anywhere I can find out about the 'density' of virtual particle creation?

Sure, just look for the non-commutation of the number operator with the Hamiltonian in non-free field theories. Besides, just attempt to calculate the energydensity that arises when the vacuum is distrubed...I refer to Zee's book QFT in a Nutshell for an introductory (yet very complete) summary

marlon
 

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