Independent virtual particle after mind experiment annihilation

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Discussion Overview

The discussion revolves around a thought experiment concerning virtual photons and their role in mediating the electromagnetic force, particularly in scenarios involving the annihilation of electrons. Participants explore the implications of virtual particles in the context of speed limits imposed by relativity and the nature of electromagnetic interactions.

Discussion Character

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

Main Points Raised

  • One participant questions whether a virtual photon can still exist if one of the electrons it mediates between is annihilated before the photon is emitted.
  • Another participant clarifies that virtual photons are mathematical constructs not bound by the same physical constraints as real photons, which travel at the speed of light.
  • A participant expresses confusion about the communication of the electromagnetic force, questioning why it is limited to the speed of light if virtual photons are not constrained in speed or energy.
  • It is noted that the nature of electromagnetic interactions differs between static fields, which involve virtual photons, and dynamic fields, which involve real photons emitted by accelerating charges.
  • One participant asserts that the thought experiment violates conservation laws, stating that an electron cannot simply "pop" out of existence.
  • A later reply affirms that the initial questions posed are valid and not silly, emphasizing the importance of adhering to physical laws in thought experiments.

Areas of Agreement / Disagreement

Participants exhibit a mix of agreement and disagreement, particularly regarding the nature of virtual versus real photons and the implications of conservation laws in hypothetical scenarios. The discussion remains unresolved on several points, particularly the interpretation of virtual photons in the context of electromagnetic force communication.

Contextual Notes

Participants express uncertainty about the implications of their thought experiments and the definitions of virtual and real photons. There is a recognition of the limitations imposed by conservation laws, but these are not fully explored or resolved within the discussion.

NoelyG
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Independent virtual particle after "mind experiment" annihilation

Hello good people,

Probably a bit of a silly question, but I have been entertaining a bit of a thought experiment about the following. Consider the following:

1. A virtual photon is exchanged between two electrons to mediate the electro-magnetic force.
2. The photon can only travel at the speed of light, so during its travel time, one electron is completely annihilated
3. Does the virtual photon still exist, or wouldn't it have been emitted in the first place?

Probably a silly question, but if any of you could shed some light on this it would be greatly appreciated. Thanks!
 
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You are confusing a real photon with a virtual photon. Virtual photons are mathematical artifacts which are not limited to any speed or energy, we refer to this as being off mass shell. If a real photon is emitted it exists until it is re-absorbed.
 


Thanks for the reply cosmik,

I guess what I was curious about was the following:

1. The electro-magnetic force can not be "communicated" faster than the speed of light
2. We have two electrons separated by a distance x
3. If one electron "pops" out of existence at time t, will the other electron still feel a repulsive force for x/c?

You say that virtual photons, which, mathematically at least, communicate the electro-magnetic force but are not limited in speed or energy - however, if this is the case, why is it that the electro-magnetic force is only communicated at the speed of light?

Sorry if these are silly questions, I am no doubt missing something fundamental. Thanks for your assistance.

EDIT: Am I correct in saying that the electro-magnetic force is communicated via virtual photons (i.e. unobservable) rather than real photons (observable)?
 
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You have to be careful when you talk about EM. The case where the field is static is different from the case when EM waves are emitted. The energy in a static field is carried by virtual photons. The energy in EM waves are carried by real photons. In the static case there is nothing to propagate the field is just there as it has always been, that's why it is called static. When a charge is accelerated it will emit EM waves which are comprised of real photons which propagate at c.

Your thought experiment violates the rules, an electron cannot pop out of existence, that would violate conservation of energy and charge, if you break the rules predictions cannot be made.
 


Thanks for taking the time to educate me cosmik, makes sense now
 


The said statements are not silly, If we thought without violating any of the physics laws for example the bulb of 60 watt will realize one photon in priscribed time.
 

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