B Is Classical EM Field the Same as Photon Wave Function?

[rubi]

What absurd consequences?

This is not a thread about BM, so I don't want to start another discussion about BM here. There are lots of things that are absurd about BM, but for the sake of not opening pandoras box, let's just stick with the example of actions at a distance.

Which interpretation are you talking about here?

I'm not talking about a specific interpretation. Any local interpretation serves as a proof for the possibility of maintaining the principle of locality in QM. Here's a list of some interpretations and the local ones are marked: https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics#Comparison_of_interpretations

 

[bhobba]

gauge forces = strong, weak, electromagnetic field non gauge forces = gravity, higgs field...what are the other non gauge forces?

Gravity can be treated as a gauge force - it just usually isn't:
https://en.wikipedia.org/wiki/Gauge_theory_gravity

The answer to where gauge forces come from is deeply mathematical and comes from symmetry. For example if you try to find the combined theory of a spin 0 particle and a spin one particles (photons) then you find they obey a certain global symmetry. But we expect from SR for them to be local. If you demand them to be local - vola - you get the EM force.

The following book gives the detail:
https://www.amazon.com/dp/3319192000/?tag=pfamazon01-20

Thanks
Bill

 

[Blue Scallop]

Think of a wave in a rope. People can hold it and move it up and down. Waves travel along the rope - but the rope or the people (they are stationary - only their arms move up and down or stay still) do not move in the direction of the wave. The rope simply moves up and down and those ups and downs move along the rope so we say waves are traveling along it. But the points on the rope are simply moving up and down. The same with EM waves. The height of the rope corresponds to the value of the EM field at that point. That's all there is - values at a particular point. But those values, just like the height of the rope, can form waves that seem to move through space. It isn't really - its just the values change to give the impression it is.

Thanks
Bill

So before the first photons from a say Supernova reaches the earth... the photons EM field are already present on Earth but the height of the rope and the moving up and down occurs outside the solar system and the disturbance slowly occurs to each field region or portion and the disturbance moves at the speed of light?

 

[bhobba]

So before the first photons from a say Supernova reaches the earth... the photons EM field are already present on Earth but the height of the rope and the moving up and down occurs outside the solar system and the disturbance slowly occurs to each field region or portion and the disturbance moves at the speed of light?

Well you are mixing quantum and classical concepts, you can't do that. I was speaking classically. Quantum Mechanically the quantum EM field is everywhere. Photons are excitation's in the field. Like all things quantum we have zero idea what's going on until its observed, so speaking of a traveling photon is not a good idea.

Classically every point in space has a value of the EM field - you can even measure it with sensitive enough equipment. Now, just like the rope, if you have an EM wave and instruments along its 'path' we would see it change like the height of the robe to be like a moving wave. That's exactly what happens with a radio antenna. It sits there at some region where EM waves pass by. The EM field changes in the antenna and electrons are set in motion, you have a current and you can detect the waves. But all that's going on is the value of the EM field at the antenna changes. Nothing is moving except the electrons in the antenna due to the changing EM field where the antenna is.

Thanks
Bill

 

[Blue Scallop]

Well you are mixing quantum and classical concepts, you can't do that. I was speaking classically. Quantum Mechanically the quantum EM field is everywhere. Photons are excitation's in the field. Like all things quantum we have zero idea what's going on until its observed, so speaking of a traveling photon is not a good idea.

Thanks
Bill

Thanks for making it clear. When you mentioned "EM field".. I thought you were talking about the quantum EM field.. maybe one should say "classical EM field" vs "quantum EM 2nd quantized field" to avoid confusion... but I got your point. In the double slit experiements.. we shouldn't think of terms of traveling electrons but electron probability waves which can interfere with it. By the way, is there no chance the classical EM field is the probability wave of the photon where the probability wave becomes physical (become Bohmized)?

 

[bhobba]

By the way, is there no chance the classical EM field is the probability wave of the photon where the probability wave becomes physical (become Bohmized)?

Maybe:
http://cds.cern.ch/record/944002/files/0604169.pdf

But an expert in BM needs to comment. I am not one.

Thanks
Bill

 

[Demystifier]

By the way, is there no chance the classical EM field is the probability wave of the photon where the probability wave becomes physical (become Bohmized)?

No there isn't. Classical EM field depends on only one position. However, it contains many photons so "Bohmization" requires a wave function that depends on many positions.

 

[atyy]

No, the Bohmians I criticize want to make you believe that the violation of Bell's inequality implies that "reality is non-local" (or alternatively "quantum mechanics is non-local"). Neither statement is justified. And presumably, the motivation for making such false claims is to make the absurd consequences of BM appear inevitable. Relaxing the standards for arguments in physics in order to have less people reject ones theory is a terrible scientific practice and that's why I call these people dishonest.

Both statements are justified once you put in all the caveats, and the caveats are well known, so they should be taken automatically, rather than assuming that people disagree with you when they don't.

 

[atyy]

If Bell had used a better term instead of local/non-local, for example a term that was not already in use, then most of the discussions about Bell's theorem would not exist. What's wrong with terms like non-separable or non-factorizable?

It is a term that lacks physics. If you insist on sticking to mathematics, you lose powerful physical consequences of Bell's theorem, such as proving that the randomness of quantum mechanics cannot be overcome if faster than light signalling is not allowed.

 

[PeterDonis]

the field is defined all over space..

All over spacetime. Yes.

so before the sunlight photons even reach the earth.. those same photon fields are already on earth??

No. There is an event in spacetime where radiation is emitted from the Sun. There is another event in spacetime where that same radiation is received on Earth. Those two events are separated by a null (lightlike) interval in spacetime. The photon field has a value at each of those events, and those values are related--that relationship is what we refer to when we say the photons "propagate" from the Sun to the Earth.

 

[Swamp Thing]

[QUOTE

They say it takes 9 minutes for the sunlight to travel to earth. You are saying it only looks like the field is propagating, but it isn't because the field is defined all over space.. so before the sunlight photons even reach the earth.. those same photon fields are already on earth?? and only the field is changing values making it looks like the sun light is travelling?

Although the field is defined all over space (time), no one says it can't have zero amplitude for a very large region. (Here the amplitude is the complex probability amplitude that you square to get detection probability).

So if we do an experiment in the lab that involves generating a field with exactly one photon at the event (Alice's Source Emits, t=0) then the field is defined accordingly. If the geometry is right, we can predict that this field will evolve over time and we end up with a high probability amplitude for the event (Bob's detector fires, $t=t_{propagation}$)

and only the field is changing values making it looks like the sun light is travelling?

In the sense described above, yes.

 

[Blue Scallop]

No there isn't. Classical EM field depends on only one position. However, it contains many photons so "Bohmization" requires a wave function that depends on many positions.

Haven't you seen Bill message in #56 (just before you posted). He said maybe. What is wrong with contents in the paper he gave:

http://cds.cern.ch/record/944002/files/0604169.pdf

 

[Demystifier]

Haven't you seen Bill message in #56 (just before you posted). He said maybe. What is wrong with contents in the paper he gave:

http://cds.cern.ch/record/944002/files/0604169.pdf

Nothing is wrong with that paper. But classical EM field is not the same thing as photon wave function, even if they satisfy the same Maxwell equations. For more details see
https://arxiv.org/abs/1205.1992 Sec. 8.3.3.5.