Does a photon carry a magnetic field?

[Kalrag]

Started doing some research into photons latley. I was wondering if photons actually carried a magnetic field.

 

[WannabeNewton]

Magnetic fields are created by moving charges. A photon in the classical sense is just a quanta of light which is propagated out as electromagnetic waves when one has an oscillating charge.

 

[Dale]

I was wondering if photons actually carried a magnetic field.

Yes. Photons are quantized excitations of the electromagnetic field.

 

[Polyrhythmic]

Started doing some research into photons latley. I was wondering if photons actually carried a magnetic field.

To clarify what the posters before me mean:

It depends on what you mean by "carry".

The photon itself doesn't produce a magnetic field, so in this sense it doesn't carry one.
The magnetic field however can be quantized, and its quantum would be the photon.

 

[Kalrag]

So in any way can photons create a magnetic field?

 

[Dale]

The magnetic field is photons.

 

[Kalrag]

The magnetic field is photons.

If that statement is true than how is a magnetic field made up of photons?

(Im still learning as an begginer)

 

[alphali]

the photon (light)is an electromagnetic wave

 

[LostConjugate]

So in any way can photons create a magnetic field?

No.

An accelerating electric charge generates a magnetic field. An accelerating electric charge also creates a wave in the electrostatic field. So when you find a wave in the electrostatic field you will also find a magnetic field.

The quanta (smallest measurable change) of the electrostatic field is a photon. So where you find a photon you find a magnetic field, the source is not the photon, it is the accelerating charge.

 

[Dale]

The magnetic force is mediated by a field. That field can be quantized. One quantum is called a photon.

Your question is like asking "how is water made up of H2O?". H2O is the name of the smallest piece of water, a photon is the name of the smallest piece of an electromagnetic field.

 

[cragar]

The photon has an oscillating E and B field.

 

[Polyrhythmic]

The photon has an oscillating E and B field.

Not really. The oscillating electromagnetic field is made of photons, but photons themselves are not the sources of any such fields.

 

[cragar]

Not really. The oscillating electromagnetic field is made of photons, but photons themselves are not the sources of any such fields.

I am talking about classical E&M, The EM wave has an E and B component. I am not saying photons are the sources of the fields, charges are the sources. Let's say we have a changing E field the induces a changing B fields and the cycle continues . Light is a self sustaining Em field.

 

[Naty1]

Dalespam nailed several different views...

If you need more, check Wikipedia, PHOTON...

 

[Polyrhythmic]

Im talking about classical E&M, The EM wave has an E and B component. I am not saying photons are the sources of the fields, charges are the sources. Let's say we have a changing E field the induces a changing B fields and the cycle continues . Light is a self sustaining Em field.

But classically, there is no photon.

 

[sophiecentaur]

But classically, there is no photon.

The problem is that people love the idea that the original 'corpuscular' theory of light was 'replaced' by a wave theory and then photons were re-introduced back into the theory to explain the quantum nature of things. SO . . . photons had to be, by popular demand, Corpuscles, again. People crave the 'little bullet' model for photons. We are fighting a losing battle here, I fear.

 

[Polyrhythmic]

The problem is that people love the idea that the original 'corpuscular' theory of light was 'replaced' by a wave theory and then photons were re-introduced back into the theory to explain the quantum nature of things. SO . . . photons had to be, by popular demand, Corpuscles, again. People crave the 'little bullet' model for photons. We are fighting a losing battle here, I fear.

I see. But in any case, I think we should stick to what the theory tells us. Classically, light is described by Maxwell's equations, which describe light as waves.

 

[sophiecentaur]

Absolutely. Hear hear.
But try to tell that to more than half the contributors to these pages who use the word Photon as it they knew exactly what it means.

 

[Polyrhythmic]

Absolutely. Hear hear.
But try to tell that to more than half the contributors to these pages who use the word Photon as it they knew exactly what it means.

Unfortunately that is also the problem with so many other subjects...

 

[davenn]

I see. But in any case, I think we should stick to what the theory tells us. Classically, light is described by Maxwell's equations, which describe light as waves.

heresy, heresy I cry

so you don't agree with any of the Richard Feynman teachings and explanations ?

Dave

 

[Dale]

I think you missed the key word "classically". I.e. not quantum mechanically. There are no photons in classical EM, by definition.

 

[Goldstone1]

To clarify what the posters before me mean:

It depends on what you mean by "carry".

The photon itself doesn't produce a magnetic field, so in this sense it doesn't carry one.
The magnetic field however can be quantized, and its quantum would be the photon.

No the magnetic quantization is not a photon, it's a monopole. A photon is a distortion in the electromagnetic field.

 

[Goldstone1]

I see. But in any case, I think we should stick to what the theory tells us. Classically, light is described by Maxwell's equations, which describe light as waves.

And yet why deny they are particles as well?

 

[Polyrhythmic]

No the magnetic quantization is not a photon, it's a monopole. A photon is a distortion in the electromagnetic field.

As the magnetic field is part of an electromagnetic field, the photon quantizes it as well.
The monopole is certainly not the quantum of the magnetic field, if anything, you could call it a hypothetical magnetic charge.
A photon is the quantum of the electromagnetic field.

 

[Polyrhythmic]

And yet why deny they are particles as well?

What do you mean by deny? The solutions to the Maxwell equations are waves, they have nothing to do with particles.

 

[Goldstone1]

What do you mean by deny? The solutions to the Maxwell equations are waves, they have nothing to do with particles.

I thought you were advocating that particles did not exist in Nature and that Maxwells Equations where absolute.

 

[Goldstone1]

As the magnetic field is part of an electromagnetic field, the photon quantizes it as well.
The monopole is certainly not the quantum of the magnetic field, if anything, you could call it a hypothetical magnetic charge.
A photon is the quantum of the electromagnetic field.

Well, we both know it is argued from both sides.

You are right, as well as am I in saying it is possible the magnetic quantization is the magnetic monopole. I wasn't trying to insinuate that the photon is not a quantization itself... sorry.

 

[sophiecentaur]

heresy, heresy I cry

so you don't agree with any of the Richard Feynman teachings and explanations ?

Dave

Before you bring Feynman into a discussion I think you should make sure that you understand just what he did say and didn't say. The 'squiggle' on a Feynman diagram in no way tells us that a particle goes from place to place, for example - can you find any evidence of his actually saying that it does?

There are a million miles between the separate ideas of quanta and particles.

 

[Polyrhythmic]

I thought you were advocating that particles did not exist in Nature and that Maxwells Equations where absolute.

I didn't, I just said that Maxwell's equations were the classical description of light.

 

[Polyrhythmic]

Well, we both know it is argued from both sides.

You are right, as well as am I in saying it is possible the magnetic quantization is the magnetic monopole. I wasn't trying to insinuate that the photon is not a quantization itself... sorry.

The magnetic monopole would play the same role as the electric charge, it would be a source for the magnetic field, not a quantization.

 

[Goldstone1]

The magnetic monopole would play the same role as the electric charge, it would be a source for the magnetic field, not a quantization.

Why would it not be a quantization of the magnetic field, if it is itself, a particle?

 

[Polyrhythmic]

Why would it not be a quantization of the magnetic field, if it is itself, a particle?

For the same reason the electron is no quantization of the electric field. I think you're mistaken on what we mean by "quantization of the field". If we look at a traveling electromagnetic wave, quantum mechanically, energy is transferred in discrete packages. Those packages are what we call photons, quanta of the field. The charge would be merely the source.

 

[Born2bwire]

Why would it not be a quantization of the magnetic field, if it is itself, a particle?

But that is not quantization. If you allow for magnetic monopoles, just as we already allow for electric monopoles, then the magnetic field will still be continuous. The quantization of the field means that the energy is quantized. Since a monopole will produce a field of continuous magnitude, there is no quantization of the field.

EDIT: It appears I lost this one by a nose.

 

[Polyrhythmic]

But that is not quantization. If you allow for magnetic monopoles, just as we already allow for electric monopoles, then the magnetic field will still be continuous. The quantization of the field means that the energy is quantized. Since a monopole will produce a field of continuous magnitude, there is no quantization of the field.

EDIT: It appears I lost this one by a nose.

Hah, gotcha! But I still think that a variety of explanations is beneficial, as long as they are not contradictory!

 

[Goldstone1]

But that is not quantization. If you allow for magnetic monopoles, just as we already allow for electric monopoles, then the magnetic field will still be continuous. The quantization of the field means that the energy is quantized. Since a monopole will produce a field of continuous magnitude, there is no quantization of the field.

EDIT: It appears I lost this one by a nose.

It's ok, we all make mistakes. :P

 

[davenn]

Before you bring Feynman into a discussion I think you should make sure that you understand just what he did say and didn't say. The 'squiggle' on a Feynman diagram in no way tells us that a particle goes from place to place, for example - can you find any evidence of his actually saying that it does?

There are a million miles between the separate ideas of quanta and particles.

you go me watching his lecture again, I think the 3rd time now :)

He catagorically states "light is particles NOT waves". and shows how experiment demonstrated that using a PM tube. "waves can explain many things, but not light, light is particles"

http://vega.org.uk/video/programme/45"

specifically, if you don't want to sit through the whole lecture... 36mins in and 48mins in


just stirring you up with the... heresy heresy I cry comment ;) but since you asked for a reference from him, I gave it :)

I am NO physicist, just a basic understanding of some things. you could baffle me with maths in an instant. But I will put my trust, on this subject, in some one with a Nobel Prize ;)

cheers
Dave

 

[Born2bwire]

you go me watching his lecture again, I think the 3rd time now :)

He catagorically states "light is particles NOT waves". and shows how experiment demonstrated that using a PM tube. "waves can explain many things, but not light, light is particles"

http://vega.org.uk/video/programme/45"

specifically, if you don't want to sit through the whole lecture... 36mins in and 48mins in


just stirring you up with the... heresy heresy I cry comment ;) but since you asked for a reference from him, I gave it :)

I am NO physicist, just a basic understanding of some things. you could baffle me with maths in an instant. But I will put my trust, on this subject, in some one with a Nobel Prize ;)

cheers
Dave

But again, the qualifier in the quote that you contested was that classically, light is waves and this is unequivocal in my opinion. The particle behavior of light does not arise unless you go to quantum electrodynamics (although we can certainly see particle behavior using classical experiments but classical theory fails to account for it). But I would even caution against labelling it as a corpuscle as that carries a very classical definition. The quantum field theory particle is not truly corpuscular, it is an amalgamation of what we classically think of as a wave and a particle.

 

[sophiecentaur]

. . . . But I would even caution against labelling it as a corpuscle as that carries a very classical definition. The quantum field theory particle is not truly corpuscular, it is an amalgamation of what we classically think of as a wave and a particle.

Yes. The problem with trying to think in terms of particles in the conventional sense is that they have to have zero extent, for a start. I say that because, would not their 'size' relate, in some way to their wavelength? This would lead to the lowest energy photons (the 'biggest' ) being the size of a mountain or a house, if you extend the implied size of light photons so that seems a non-starter for a good model. So how would these infinitely small particles be expected to interact with the structures they encounter as they would mostly be encountering empty space (analogous to the results of Rutherford scattering)?
To explain how they actually could interact, you'd have to give them some field around them so why not stick with the EM wave to explain it all. The Quantisation aspect need only refer to the energy needed for an interaction to occur and needn't involve these little bullets - except as a useful shorthand, which I agree is useful.