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Photons And The Electromagnetic Field


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#1 Flummoxed

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Posted 11 May 2019 - 08:41 AM

After a mind numbing discussion with some bored retired professionals, on another forum. I found these two informative links which discuss Photons and the electromagnetic field via various different theories and view points.

 

https://van.physics....omagnetic-force

https://van.physics....ting.php?id=414

 

 


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#2 fahrquad

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Posted 11 May 2019 - 09:11 AM

What kind of professionals?  Even prostitution is considered a profession.  :Crunk:



#3 exchemist

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Posted 11 May 2019 - 09:15 AM

After a mind numbing discussion with some bored retired professionals, on another forum. I found these two informative links which discuss Photons and the electromagnetic field via various different theories and view points.

 

https://van.physics....omagnetic-force

https://van.physics....ting.php?id=414

Since I see the first link makes a reference to "virtual" photons, allow me to add another link, explaining a bit what these are and what they are not.

 

(Spolier: they are not photons, basically.)  

 

https://profmattstra...-what-are-they/


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#4 Flummoxed

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Posted 11 May 2019 - 09:15 AM

What kind of professionals?  Even prostitution is considered a profession.  :Crunk:

 

They did not ask for any kind of payment. But I guess any form of payed work can be considered prostitution. 



#5 Flummoxed

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Posted 11 May 2019 - 09:43 AM

Since I see the first link makes a reference to "virtual" photons, allow me to add another link, explaining a bit what these are and what they are not.

 

(Spolier: they are not photons, basically.)  

 

https://profmattstra...-what-are-they/

 

I have read this link before, it puts meat on the bones of some of the points of view above. Prof Strasslers explanations are always informative. It is often a good starting point to include his name in any search. 

 

The common idea that a single photon only goes in a straight line, but radio waves which are commonly thought to be made up of photons can bend around the earths surface, seem incompatible, until you start to look very closely at what is being talked about. 

 

I was taught that radio WAVES were due to the polarization of space, and this was easily modelled with Maxwells equations, this WAVE today is thought to be due to virtual particles or virtual photons or both or real photons which as you point out above is highly unlikely. 

 

When one considers how a single photon must really move through the quantum foam of space, it must be interacting with virtual particles. Momentarily being absorbed and emitted. When zooming out it goes in a straight line, but when zoomed in, it might be getting a rough ride. 

 

It could be the properties of space at the quantum foam level restrict the speed of light. c2=1/uE If the permeability or permittivity of space was different in the early universe would the speed of light have been different. 


Edited by Flummoxed, 11 May 2019 - 09:44 AM.


#6 exchemist

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Posted 11 May 2019 - 10:01 AM

I have read this link before, it puts meat on the bones of some of the points of view above. Prof Strasslers explanations are always informative. It is often a good starting point to include his name in any search. 

 

The common idea that a single photon only goes in a straight line, but radio waves which are commonly thought to be made up of photons can bend around the earths surface, seem incompatible, until you start to look very closely at what is being talked about. 

 

I was taught that radio WAVES were due to the polarization of space, and this was easily modelled with Maxwells equations, this WAVE today is thought to be due to virtual particles or virtual photons or both or real photons which as you point out above is highly unlikely. 

 

When one considers how a single photon must really move through the quantum foam of space, it must be interacting with virtual particles. Momentarily being absorbed and emitted. When zooming out it goes in a straight line, but when zoomed in, it might be getting a rough ride. 

 

It could be the properties of space at the quantum foam level restrict the speed of light. c2=1/uE If the permeability or permittivity of space was different in the early universe would the speed of light have been different. 

Forget the idea that there is any difference between radio waves and visible light or gamma rays, where photons are concerned.

 

All are EM radiation and therefore all are quantised, their energy being detectable only in multiples of hν. In practical radio applications, this photon character does not result in any phenomena requiring a QM explanation, that's all. But the photons - real photons, not virtual ones - are still there.  

 

Virtual photons are invoked in modelling how the electric and magnetic interactions between QM entities are mediated in QFT.  Those are not real photons, just disturbances in the EM field that are modelled in a similar way, as Strassler explains. 

 

(It is by the way wrong to think of photons are travelling in straight lines. The double slit experiment shows the weakness of this idea.  But you know that, I think :) )



#7 Flummoxed

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Posted 11 May 2019 - 11:59 AM

Forget the idea that there is any difference between radio waves and visible light or gamma rays, where photons are concerned.

 

All are EM radiation and therefore all are quantised, their energy being detectable only in multiples of hν. In practical radio applications, this photon character does not result in any phenomena requiring a QM explanation, that's all. But the photons - real photons, not virtual ones - are still there.  

 

Virtual photons are invoked in modelling how the electric and magnetic interactions between QM entities are mediated in QFT.  Those are not real photons, just disturbances in the EM field that are modelled in a similar way, as Strassler explains. 

 

(It is by the way wrong to think of photons are travelling in straight lines. The double slit experiment shows the weakness of this idea.  But you know that, I think :) )

 

Yes I am aware of the double slit experiment, every one is.

 

Your reply seems a little confused, There are different ways of viewing photons I think the links I provided above clearly show this.

 

A virtual photon does not have the same properties as a real photon. When describing an EM wave, electrically polarised virtual photons are assumed to exist. Real Photons have no electrical properties, they are electrically neutral and transfer only momentum, they are not influenced in any way by passing through an electric or magnetic field.

 

Amusing little experiment> Photons have a polarisation as can be seen with a simple experiment with two pairs of polarised sunglasses held at 90 degrees to each other. The polarisation of light can be changed by adding a third pair at 45 degrees between the others. With two sets of glasses all light is blocked, adding the third set light once again can pass albeit at a reduced intensity. 

 

A photon of light is a quanta of energy, with perhaps wave and particle properties, and polarisation depending on the experiment used to detect it. The experiment can arguably affect the results. For example > Multiple Wave particle superpositions do not explain the double slit experiment when the experiment is performed in multiple labs using just a single photon. When the results from all the labs are brought together the combined results show the same bands on the screen as would be seen in the double slit experiment when firing multiple photons, clearly no wave superposition took place in the single photon experiment.

 

In the double slit experiment no consideration is given to the fact that photons leaving an emitter might leave the emitter from slightly different parts of the emitter. No consideration is given to the atmosphere the photons travel through. A localized photon field travelling through space likely will interact with objects as it approaches them before it is absorbed. ie it might be safer not to view an individual Photon as a wave.  (Bohm, de Broglie pilot waves are an interesting alternative way at looking at photons in the double slit experiment) 

 

Real photons do not have the same properties as virtual photons. Magnetic field lines due to virtual photons for example bend in a way a real photon can not.

 

The term photon I think is used in many different ways. A real photon is regularly confused with virtual photons which can be ascribed a multitude of properties that a real photon has not.

 

One explanation for radio waves is that in the near field virtual particles interact producing real detectable photons, which travel as a radio wave, bending around the surface of the earth. Another explanation is that the electrical field around an antennae polarizes the space around it via virtual particles and it is this polarizing of space that ripples outwards as a radio wave, slowly weakening as it moves outwards. It has been claimed that individual photons in a radio wave have been detected.

If the radio wave consists of real photons they transfer inertia to the electrons in the receiver, if it is composed of a wave of electrically polarized virtual particles it transfers an emf to the receiver. I tend to view the second explanation as more plausible. 

 

I wonder why I am mentioning this :) A field meter measures volts / metre. When standing in a field from a active Tesla coil amalgam fillings hurt. Photons are emitted as electrons recombine with the ionized plasma. Not unlike CBR in the theoretical Big Bang.  



#8 OceanBreeze

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Posted 11 May 2019 - 12:14 PM

I don’t think radio waves bend around the earth’s surface, the way you are suggesting.

 

They do get refracted, according to Snell’s Law:

 

maxresdefault.jpg

 

 

From the above link:

Gradual changes in refractive index

Rather than a sudden boundary to two different media, radio waves will often be refracted by areas where the refractive index gradually changes.

This may happen as the radio waves propagate through the atmosphere where small changes in refractive index occur.

Typically it is found that the refractive index of the air is higher close to the earth’s surface, falling slightly with height.

In this case the radio waves are refracted towards the area of higher refractive index. This extends the range over which they can travel.

 


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#9 Flummoxed

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Posted 11 May 2019 - 12:24 PM

Yes, this does happen at higher frequencies. reflection from the ionosphere etc

 

But yea old long wave can bend around the surface of the earth, and around hills. This I understand is because the refractive index of the ground and sea is less more :unsure: than the air, so radio waves can bend in exactly the same as when light passes through water.



#10 exchemist

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Posted 11 May 2019 - 03:20 PM

Don't forget diffraction. With wavelengths of the order of hundreds or even thousands of of metres, a lot of obstructions have dimensions smaller than the wavelength and  are simply irrelevant to the wave propagation.



#11 Flummoxed

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Posted 12 May 2019 - 08:34 PM

Don't forget diffraction. With wavelengths of the order of hundreds or even thousands of of metres, a lot of obstructions have dimensions smaller than the wavelength and  are simply irrelevant to the wave propagation.

 

Maybe /I should have wrote bent to cover refraction diffraction :)

 

If you view radio waves as virtual photons (or maybe polarized virtual particle pairs), and not real photons, as would have been emitted in the big bang recombination stage. How would Cobe or Planck discriminate noise from random radio waves made of virtual photons over billions of years, and real photons from the Big Bang. ?



#12 exchemist

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Posted 13 May 2019 - 06:00 AM

Maybe /I should have wrote bent to cover refraction diffraction :)

 

If you view radio waves as virtual photons (or maybe polarized virtual particle pairs), and not real photons, as would have been emitted in the big bang recombination stage. How would Cobe or Planck discriminate noise from random radio waves made of virtual photons over billions of years, and real photons from the Big Bang. ?

Virtual photons are disturbances with only a transient existence, as Strassler makes reasonably clear, I think.

 

So you cannot view an enduring physical phenomenon like a radio wave in this way. You can't make anything out of virtual photons. 


Edited by exchemist, 13 May 2019 - 06:00 AM.


#13 Flummoxed

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Posted 13 May 2019 - 11:17 AM

Virtual photons are disturbances with only a transient existence, as Strassler makes reasonably clear, I think.

 

So you cannot view an enduring physical phenomenon like a radio wave in this way. You can't make anything out of virtual photons. 

 

I can transmit a lot of forces using virtual photons under QED.

 

Yes I know virtual particles are transient in nature and transmit various forces, including I understand the electromagnetic force. Virtual photons can have more states than a real photon, and can interact with charged particles, to transmit forces. For example a stream of real photons quanta could not produce a magnetic field, it is created by virtual photons, interacting with a cloud of virtual particles. Virtual particles do exist as is claimed to be evidenced by the Casimir effect, and further evidenced by the dynamic Casimir effect. 

 

Hydrogen atoms give of real photons which carry away inertia, when the atom go to lower energy states. Those photons have specific energy levels and I would have thought allowing for red shift, should be detectable in the CBR. A Hydrogen atom does not give of a omnidirectional radio wave, it gives of discrete quanta ie photons or am I wrong again?  



#14 exchemist

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Posted 13 May 2019 - 03:25 PM

I can transmit a lot of forces using virtual photons under QED.

 

Yes I know virtual particles are transient in nature and transmit various forces, including I understand the electromagnetic force. Virtual photons can have more states than a real photon, and can interact with charged particles, to transmit forces. For example a stream of real photons quanta could not produce a magnetic field, it is created by virtual photons, interacting with a cloud of virtual particles. Virtual particles do exist as is claimed to be evidenced by the Casimir effect, and further evidenced by the dynamic Casimir effect. 

 

Hydrogen atoms give of real photons which carry away inertia, when the atom go to lower energy states. Those photons have specific energy levels and I would have thought allowing for red shift, should be detectable in the CBR. A Hydrogen atom does not give of a omnidirectional radio wave, it gives of discrete quanta ie photons or am I wrong again?  

Sure you can but these remain transient disturbances and are not particles with an independent existence. By contrast a photon, once formed, can continue forever, so long as it does not interact with something en route.

 

The  Casimir effect, by the way, is explained perfectly well by good old van der Waals forces, which we all learnt about in the 6th form at school. Here is an explanation from physics stack exchange:

 

"The Casimir effect and the Van der Waals force between two conducting plates are one and the same thing.

To see this, consider the boundary conditions postulated for the Casimir effect. The electric field has to be exactly zero at the plates. Because of this, it is said, the zero point energy of the vacuum is lower in between the plates than outside, which causes the interaction. But these references to the vacuum and virtual particles are mere heuristics. What does it mean for the electric field to be zero at the plates? The charges in the plate will have to redistribute and polarize the plate to generate a corresponding field.

But the interactions between fluctuating polarizations are precisely the dispersion forces that are responsible for the Van der Waals interaction.

Thus they are two explanation of the same phenomenon."


Edited by exchemist, 13 May 2019 - 03:25 PM.


#15 Flummoxed

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Posted 14 May 2019 - 02:48 AM

Sure you can but these remain transient disturbances and are not particles with an independent existence. By contrast a photon, once formed, can continue forever, so long as it does not interact with something en route.

 

The  Casimir effect, by the way, is explained perfectly well by good old van der Waals forces, which we all learnt about in the 6th form at school. Here is an explanation from physics stack exchange:

 

"The Casimir effect and the Van der Waals force between two conducting plates are one and the same thing.

To see this, consider the boundary conditions postulated for the Casimir effect. The electric field has to be exactly zero at the plates. Because of this, it is said, the zero point energy of the vacuum is lower in between the plates than outside, which causes the interaction. But these references to the vacuum and virtual particles are mere heuristics. What does it mean for the electric field to be zero at the plates? The charges in the plate will have to redistribute and polarize the plate to generate a corresponding field.

But the interactions between fluctuating polarizations are precisely the dispersion forces that are responsible for the Van der Waals interaction.

Thus they are two explanation of the same phenomenon."

 

Again yes, I think the confusion is the way in which photons are defined, real or virtual. A real photon has clearly defined properties whereas a virtual photon has it seems what ever property anyone wants to ascribe to it, to fulfil a purpose. Again magnetic field, can not be achieved with real photon exchanges. Likewise I don't think an electro magnetic field can be achieved by real photons transferring momentum from the near field of transmitter A to receiver B.

 

Relatively speaking :) Point of confusion a virtual photon travelling at c will not experience time, how virtual is that? 

 

Again Yes. You have previously mentioned Van der Waals forces, that is also why I also mentioned the dynamic Casimir effect, which can not be achieved with Van der Waals forces. The HUP and the whole of quantum field theory rests on virtual particles of various types, so whilst the Van de Waals force might be a equally plausible explanation, I assume you do not deny the HUP and Quantum field theory might be mostly correct :) 

 

Any way the point I was trying to get at, due to rhertz (its not my fault) is the CBR made up of real photons which would have been emitted from hydrogen atoms with (specific energy levels) in the big bang as they cooled down, or is it radio waves consisting of virtual particles from some other random source, exhibiting no discernable spike relating to Hydrogen atoms recombining and cooling in the early universe.