Electromagnetic inertial reaction force?

[jcap]

I accelerate charged particle $A$ causing virtual photons to travel to distant charged particle $B$ which feels an electromagnetic force proportional to $A$'s acceleration (for a classical field description of this effect see https://www.feynmanlectures.caltech.edu/I_28.html Eqn 28.6).

Virtual photons conserve momentum and energy between the two charged particles.

Is there an inertia-like reaction force back at particle $A$?

 

[tech99]

My understanding is that when we accelerate a charge it feels a force trying to stop it moving.This is caused because its static field lines are bent back and so apply a retarding force. The work done in accelerating the charge is partly lost as radiated energy and partly stored as inertia. Particle B feels a force due to the electric field of the radiated wave.

 

[PeroK]

I accelerate charged particle $A$ causing virtual photons to travel to distant charged particle $B$ which feels an electromagnetic force proportional to $A$'s acceleration (for a classical field description of this effect see https://www.feynmanlectures.caltech.edu/I_28.html Eqn 28.6).

Virtual photons conserve momentum and energy between the two charged particles.

Is there an inertia-like reaction force back at particle $A$?

There is no photon in classical physics, let alone virtual photons. Your post is, therefore, confusing different theories of light.

 

[jcap]

There is no photon in classical physics, let alone virtual photons. Your post is, therefore, confusing different theories of light.

But I am describing a physical situation that should be describable by both classical and quantum theories of electromagnetism.

 

[PeroK]

But I am describing a physical situation that should be describable by both classical and quantum theories of electromagnetism.

Not by mixing and matching concepts from both theories. There are no forces in QED (in the sense of Newton's laws and Coulomb's law).

 

[jcap]

My understanding is that when we accelerate a charge it feels a force trying to stop it moving.This is caused because its static field lines are bent back and so apply a retarding force. The work done in accelerating the charge is partly lost as radiated energy and partly stored as inertia. Particle B feels a force due to the electric field of the radiated wave.

In the situation I described above quantum electrodynamics would imply an exchange of energy and momentum between particle $A$ and particle $B$. I would have thought this would translate into a reaction force back at particle $A$.

 

[jcap]

Not by mixing and matching concepts from both theories. There are no forces in QED.

Yes but classical forces imply changes in momentum which is a concept described in QED.

The virtual photons in QED conserve momentum so there should be a classical reaction force back at particle $A$.

 

[PeroK]

Yes but classical forces imply changes in momentum which is a concept described in QED.

The virtual photons in QED conserve momentum so there should be a classical reaction force back at particle $A$.

Do you mean:

For every virtual photon, there is an equal and opposite virtual photon?

 

[jcap]

Do you mean:

For every virtual photon, there is an equal and opposite virtual photon?

When a virtual photon adds a certain amount of energy and momentum to particle $B$ then that same amount of energy and momentum must have been lost from particle $A$.

 

[PeroK]

When a virtual photon adds a certain amount of energy and momentum to particle $B$ then that same amount of energy and momentum must have been lost from particle $A$.

In other words, QED is just Newton's laws with virtual photons as mediators!

 

[vanhees71]

No! QED is the quantum version of the relativistic theory of interacting electrically charged particles and the electromagnetic field. Instead of saying "virtual photons" just say "electromagnetic interaction" and you avoid all these misunderstandings propagated (faster than light ;-)) by popular-science books.

 

[weirdoguy]

Yes but classical forces imply changes in momentum which is a concept described in QED.

Yes, but not the way you try to do it. I see no point in using QED concepts unless you thoroughly know and understand them. Virtual particles are widely misunderstood by general audience (and even some physicsts). These insights are a good start:

https://www.physicsforums.com/insights/misconceptions-virtual-particles/
https://www.physicsforums.com/insights/physics-virtual-particles/

 

[Dale]

Not by mixing and matching concepts from both theories. There are no forces in QED (in the sense of Newton's laws and Coulomb's law).

I 100% agree here. @jcap please pick one theory and stick to it. If you want to learn about the other theory then do that in a separate thread.

This is the classical physics forum so discussions about quantum mechanics is off topic anyway. This thread is closed, but you are welcome to start more focused threads on the same topic.