Radio waves propagate spherically, how comes the photon moves in a straight line

[paulca]

If you put two floating plungeres in a large pool of water and start bouncing one up and down.  The other one starts to bounce up and down.

No water "flowed".  Energy was transfered.  This is exactly what waves do.

It was the way particle duality was put to me that rachetted one more click of understanding.  The simple point was "Here" is a particle.  You can give it a point reference and say, "There is the particle".  The diagram was replaced by a wave.  Question: "Where is the wave?"....  oh.... ah.... I see.

Technically water did flow.  Volume under the curve does not magically appear.

[studiot]

If you put two floating plungeres in a large pool of water and start bouncing one up and down.  The other one starts to bounce up and down.

No water "flowed".  Energy was transfered.  This is exactly what waves do.

It was the way particle duality was put to me that rachetted one more click of understanding.  The simple point was "Here" is a particle.  You can give it a point reference and say, "There is the particle".  The diagram was replaced by a wave.  Question: "Where is the wave?"....  oh.... ah.... I see.

Technically water did flow.  Volume under the curve does not magically appear.

So go on, in what way is your analogy compared to the OP question ?

According to duality, photons and radio waves are the same thing.

Plungers and water waves are not.

[paulca]

If you put two floating plungeres in a large pool of water and start bouncing one up and down.  The other one starts to bounce up and down.

No water "flowed".  Energy was transfered.  This is exactly what waves do.

It was the way particle duality was put to me that rachetted one more click of understanding.  The simple point was "Here" is a particle.  You can give it a point reference and say, "There is the particle".  The diagram was replaced by a wave.  Question: "Where is the wave?"....  oh.... ah.... I see.

Technically water did flow.  Volume under the curve does not magically appear.

So go on, in what way is your analogy compared to the OP question ?

According to duality, photons and radio waves are the same thing.

Plungers and water waves are not.

Im just bouncing analogies onto analogies.  Most of the physics involved are analogies themselves and proudly so.  Approximations that facilitate modelling nature and producing useful outcomes.

Nobody believes there really is a little particle with a "e" T-Shirt on it.  Seriously.

[MrAl]

If you put two floating plungeres in a large pool of water and start bouncing one up and down.  The other one starts to bounce up and down.

No water "flowed".  Energy was transfered.  This is exactly what waves do.

It was the way particle duality was put to me that rachetted one more click of understanding.  The simple point was "Here" is a particle.  You can give it a point reference and say, "There is the particle".  The diagram was replaced by a wave.  Question: "Where is the wave?"....  oh.... ah.... I see.

Technically water did flow.  Volume under the curve does not magically appear.

So go on, in what way is your analogy compared to the OP question ?

According to duality, photons and radio waves are the same thing.

Plungers and water waves are not.

Hi,

I am guessing that Paulca was replying to my post just before that one, where I mentioned AC current where electrons may move back and forth but never go anywhere permanently.

[MrAl]

If you put two floating plungeres in a large pool of water and start bouncing one up and down.  The other one starts to bounce up and down.

No water "flowed".  Energy was transfered.  This is exactly what waves do.

It was the way particle duality was put to me that rachetted one more click of understanding.  The simple point was "Here" is a particle.  You can give it a point reference and say, "There is the particle".  The diagram was replaced by a wave.  Question: "Where is the wave?"....  oh.... ah.... I see.

Technically water did flow.  Volume under the curve does not magically appear.

So go on, in what way is your analogy compared to the OP question ?

According to duality, photons and radio waves are the same thing.

Plungers and water waves are not.

Im just bouncing analogies onto analogies.  Most of the physics involved are analogies themselves and proudly so.  Approximations that facilitate modelling nature and producing useful outcomes.

Nobody believes there really is a little particle with a "e" T-Shirt on it.  Seriously.

Hi,

That is the amazing thing about the quantum world.  There are no analogies for some quantum phenomena because we always try to boil it down to a classical explanation.  There's nothing we can do about it, we have to just "accept" that the quantum world works differently than in our usual world.

If an alien came to visit us from some distant planet, would we try to come up with a formula for aliens?
Maybe, but we'd most likely just accept it as is.  That would be something new also that we would have to just accept.

What seems amazing to me is HOW different it can be.  It's almost incredible, unless you factor in the fact that we simply don't know everything about the universe, yet.  Then it's not as amazing because we know that new things will come up that we don't really understand the way we normally understand things.

Ok, so where did my Fosters go...

[studiot]

If you put two floating plungeres in a large pool of water and start bouncing one up and down.  The other one starts to bounce up and down.

No water "flowed".  Energy was transfered.  This is exactly what waves do.

It was the way particle duality was put to me that rachetted one more click of understanding.  The simple point was "Here" is a particle.  You can give it a point reference and say, "There is the particle".  The diagram was replaced by a wave.  Question: "Where is the wave?"....  oh.... ah.... I see.

Technically water did flow.  Volume under the curve does not magically appear.

So go on, in what way is your analogy compared to the OP question ?

According to duality, photons and radio waves are the same thing.

Plungers and water waves are not.

Im just bouncing analogies onto analogies.  Most of the physics involved are analogies themselves and proudly so.  Approximations that facilitate modelling nature and producing useful outcomes.

Nobody believes there really is a little particle with a "e" T-Shirt on it.  Seriously.

Hi,

That is the amazing thing about the quantum world.  There are no analogies for some quantum phenomena because we always try to boil it down to a classical explanation.  There's nothing we can do about it, we have to just "accept" that the quantum world works differently than in our usual world.

If an alien came to visit us from some distant planet, would we try to come up with a formula for aliens?
Maybe, but we'd most likely just accept it as is.  That would be something new also that we would have to just accept.

What seems amazing to me is HOW different it can be.  It's almost incredible, unless you factor in the fact that we simply don't know everything about the universe, yet.  Then it's not as amazing because we know that new things will come up that we don't really understand the way we normally understand things.

Ok, so where did my Fosters go...

With these sorts of replies, I don't see that people are serious about the subject.


I agree that the model of one phenomenon exhibits differences from the model of a different phenomenon.
Why would anyone expect it to be otherwise ?
But it is also true that there is often commonality between pairs of models that allow one to be used as analogs for the other  - in the right circumstances.

For instance both classical wave theory and QM have an uncertainty principle.
The classical version starts with Parseval's theorem and several  pages of maths later ends with the conclusion that   Δt Δω  ≥  1/2,
when considering non recurrent waveforms.

So here we can see some commonality between classical and quantum.

However in the classical model the wave variable, φ,  has a physical meaning in out material universe.

On the other hand the wave variable in quantum theory does not correspond to any physical variable, certainly not probability as some proclaim.
In fact in only takes a few lines of maths to prove that Ψ cannot represent probability which is positive definite, while Ψ has positive and negative parts.

Nevertheless quantum theory cannot do without classical underpinning since the forces and energies involved are classical quantities ( non relativistic or relativistic as appropriate).

Another difference often overlooked is that classical analysis looks for solutions to the wave or other equations since its variable, φ, represents some material world quantity.

Quantisation looks for the zeros of the solutions to the corresponding quantum equations to meet energy requirements.

[showman]

Nevertheless quantum theory cannot do without classical underpinning since the forces and energies involved are classical quantities ( non relativistic or relativistic as appropriate).

Quantisation looks for the zeros of the solutions to the corresponding quantum equations to meet energy requirements.

A QM system, a particle for example, does not need to have a definite energy, same way it does not have to have definite position. How is that exactly classical? And what are the "energy requirements" in that case that have to be met?

[Marco]

According to duality, photons and radio waves are the same thing.

You can pretend a collective matter wave consists of bunch of fuzzy photons, those are the same thing ... but they are not the same as unquantised EM waves which I think of hearing radio waves.

It's a triality.

[radiolistener]

A QM system, a particle for example, does not need to have a definite energy, same way it does not have to have definite position. How is that exactly classical?

I think the problem here is that a QM "particle" is treated as if it were the same kind of object as a classical "particle", simply because we use the same word "particle" for both. But they are fundamentally different things.

The same word can mean different things depending on the context, but using the same word does not imply that the two concepts are physically equivalent or that the properties of a classical particle can simply be applied to a QM particle and vice versa.

[showman]

To be honest, I don't exactly know what studiot meant, but by singling out forces and energies specifically, my best guess was that what was meant was that those are somehow deterministic/classical even in QM, whereas something like positions and momenta might be not. And I wanted to point out that the same indeterminacy, depending on particular state, applies to energies and forces as well, particles or not.

[studiot]

According to duality, photons and radio waves are the same thing.

You can pretend a collective matter wave consists of bunch of fuzzy photons, those are the same thing ... but they are not the same as unquantised EM waves which I think of hearing radio waves.

It's a triality.

I'm not pretending anything.

But it would be helpful to your understanding if you didn't take my remark out of context but with reference to the post it was answering

If you put two floating plungeres in a large pool of water and start bouncing one up and down.  The other one starts to bounce up and down.

No water "flowed".  Energy was transfered.  This is exactly what waves do.

It was the way particle duality was put to me that rachetted one more click of understanding.  The simple point was "Here" is a particle.  You can give it a point reference and say, "There is the particle".  The diagram was replaced by a wave.  Question: "Where is the wave?"....  oh.... ah.... I see.

Technically water did flow.  Volume under the curve does not magically appear.

Perhaps I did not state my answer very well so I will rephrase it more fully.

Neither plunger are part of the water wave, which is a mechanical wave.
The wave is formed in the medium, which is comprised solely of water.
The wave motion may be considered either as an exercise in continuum mechanics or as an exercise in fluid mechanics 'fluid elements aka particles' .
Both analyses lead to the same (classical) results.
All the variables in both analyses are real physical mechanical variables.  Mass, momentum, gravity as a restoring force, the energy of a harmonic oscillator, the period or frequency of the oscillator and the wave and so on.
Quantum mechanics does not arise for this type of wave system, although it obeys resonance curves and requirements.

I have never claimed that any sort of (quantum) matter wave consists of a bunch of fuzzy photons.
or that EM waves, including radio waves, are any sort of 'matter waves'.

EM waves are quite different in that there is no pre-existing medium and that the medium has no mass.
Consequently when considered as particulate (photons) they cannot be 'matter waves'.
Indeed photons lack the controlling quantum numbers (principal, azimuthal and magnetic) for matter waves.
The do however possess spin quantum numbers, which produce quantum effects of no interest (as far as I am aware ) in radio waves.

[showman]

Leaving water aside, photons and radio waves are still not the same thing. There is no duality that claims that.

For those who are really interested, I recommend first this, as it's quite short https://www.classe.cornell.edu/spr/2000-02/msg0022377.html
And then perhaps something like Introduction to Quantum Optics by Grynberg, Aspect and Fabre, especially chapters 4 and 5. You can even ignore the mathematics if you don't care, as there is a lot of explaining text.
Once everyone knows about number, coherent, squeezed, one-photon multimode, and other possible states of the quantized EM field, this topic might eventually conclude.

[MrAl]

If you put two floating plungeres in a large pool of water and start bouncing one up and down.  The other one starts to bounce up and down.

No water "flowed".  Energy was transfered.  This is exactly what waves do.

It was the way particle duality was put to me that rachetted one more click of understanding.  The simple point was "Here" is a particle.  You can give it a point reference and say, "There is the particle".  The diagram was replaced by a wave.  Question: "Where is the wave?"....  oh.... ah.... I see.

Technically water did flow.  Volume under the curve does not magically appear.

So go on, in what way is your analogy compared to the OP question ?

According to duality, photons and radio waves are the same thing.

Plungers and water waves are not.

Im just bouncing analogies onto analogies.  Most of the physics involved are analogies themselves and proudly so.  Approximations that facilitate modelling nature and producing useful outcomes.

Nobody believes there really is a little particle with a "e" T-Shirt on it.  Seriously.

Hi,

That is the amazing thing about the quantum world.  There are no analogies for some quantum phenomena because we always try to boil it down to a classical explanation.  There's nothing we can do about it, we have to just "accept" that the quantum world works differently than in our usual world.

If an alien came to visit us from some distant planet, would we try to come up with a formula for aliens?
Maybe, but we'd most likely just accept it as is.  That would be something new also that we would have to just accept.

What seems amazing to me is HOW different it can be.  It's almost incredible, unless you factor in the fact that we simply don't know everything about the universe, yet.  Then it's not as amazing because we know that new things will come up that we don't really understand the way we normally understand things.

Ok, so where did my Fosters go...

With these sorts of replies, I don't see that people are serious about the subject.


I agree that the model of one phenomenon exhibits differences from the model of a different phenomenon.
Why would anyone expect it to be otherwise ?
But it is also true that there is often commonality between pairs of models that allow one to be used as analogs for the other  - in the right circumstances.

For instance both classical wave theory and QM have an uncertainty principle.
The classical version starts with Parseval's theorem and several  pages of maths later ends with the conclusion that   Δt Δω  ≥  1/2,
when considering non recurrent waveforms.

So here we can see some commonality between classical and quantum.

However in the classical model the wave variable, φ,  has a physical meaning in out material universe.

On the other hand the wave variable in quantum theory does not correspond to any physical variable, certainly not probability as some proclaim.
In fact in only takes a few lines of maths to prove that Ψ cannot represent probability which is positive definite, while Ψ has positive and negative parts.

Nevertheless quantum theory cannot do without classical underpinning since the forces and energies involved are classical quantities ( non relativistic or relativistic as appropriate).

Another difference often overlooked is that classical analysis looks for solutions to the wave or other equations since its variable, φ, represents some material world quantity.

Quantisation looks for the zeros of the solutions to the corresponding quantum equations to meet energy requirements.

Hello again,

Well I am not sure what you are trying to say here.  First it sounds like some sort of mocking, which for one is untrue as told by the number of replies, but you don't need to mock anybody out you just need to state your case.

Anyway, it sounds like you are taking an apple and a pear and saying that they both grow on trees.  Yes they both have that in common, but it's a very vague commonality.  Now if you said (and if it was true) that pears have the same seeds as apples, THAT would be a very interesting commonality which would take some explaining.  By "same" I mean exactly the same, no difference whatsoever.

START_QUOTE
On the other hand the wave variable in quantum theory does not correspond to any physical variable, certainly not probability as some proclaim.
END_QUOTE

Where are you getting this information from?  What are you considering the "wave variable" to be?
The wavefunction is a probability function.  Check out "probability amplitudes" of the wavefunction.  Check out the square of that also.
Also check out the Born rule.

[MrAl]

Leaving water aside, photons and radio waves are still not the same thing. There is no duality that claims that.

For those who are really interested, I recommend first this, as it's quite short https://www.classe.cornell.edu/spr/2000-02/msg0022377.html
And then perhaps something like Introduction to Quantum Optics by Grynberg, Aspect and Fabre, especially chapters 4 and 5. You can even ignore the mathematics if you don't care, as there is a lot of explaining text.
Once everyone knows about number, coherent, squeezed, one-photon multimode, and other possible states of the quantized EM field, this topic might eventually conclude.

Is there a reason you seem to want this topic to conclude?
When people talk, they often talk back and forth a lot in order to understand each other and bring out related information.  It's normal.

[studiot]

Leaving water aside, photons and radio waves are still not the same thing. There is no duality that claims that.

For those who are really interested, I recommend first this, as it's quite short https://www.classe.cornell.edu/spr/2000-02/msg0022377.html
And then perhaps something like Introduction to Quantum Optics by Grynberg, Aspect and Fabre, especially chapters 4 and 5. You can even ignore the mathematics if you don't care, as there is a lot of explaining text.
Once everyone knows about number, coherent, squeezed, one-photon multimode, and other possible states of the quantized EM field, this topic might eventually conclude.

Your comment about not bothering with the water analogy (which was not mine) leads me to wonder if you know the difference between a simple harmonic oscillator (which was also mentioned in your reference) and a wave.

I read the reference from Dr Kinsler and it seems to me that he was saying more or less what I was saying, though he also addressed EM topics not relevant to radio waves.

Here is an interesting thought experiment where I ask you to predict the outcome by whatever means you choose.
Then I will post the results of a similar actual experiment by Mike Morris, University of Rochester.
This experiment actually demonstrates the answer to the OP question very convincingly.

So imagine you have a photon source that can produce from one single photon to many many photons at the turn of a calibrated dial.
Also you have a detector capable of detecting from one single photon to many many nearly coincident ones.

So you aim the source, set to single photon mode, at the detector and confirm that your detector reliably detects the transmitted photon.
Now move the detector slightly off beam and then further off beam, recording what you see.

Now please predict what happens ?

[studiot]

If you put two floating plungeres in a large pool of water and start bouncing one up and down.  The other one starts to bounce up and down.

No water "flowed".  Energy was transfered.  This is exactly what waves do.

It was the way particle duality was put to me that rachetted one more click of understanding.  The simple point was "Here" is a particle.  You can give it a point reference and say, "There is the particle".  The diagram was replaced by a wave.  Question: "Where is the wave?"....  oh.... ah.... I see.

Technically water did flow.  Volume under the curve does not magically appear.

So go on, in what way is your analogy compared to the OP question ?

According to duality, photons and radio waves are the same thing.

Plungers and water waves are not.

Im just bouncing analogies onto analogies.  Most of the physics involved are analogies themselves and proudly so.  Approximations that facilitate modelling nature and producing useful outcomes.

Nobody believes there really is a little particle with a "e" T-Shirt on it.  Seriously.

Hi,

That is the amazing thing about the quantum world.  There are no analogies for some quantum phenomena because we always try to boil it down to a classical explanation.  There's nothing we can do about it, we have to just "accept" that the quantum world works differently than in our usual world.

If an alien came to visit us from some distant planet, would we try to come up with a formula for aliens?
Maybe, but we'd most likely just accept it as is.  That would be something new also that we would have to just accept.

What seems amazing to me is HOW different it can be.  It's almost incredible, unless you factor in the fact that we simply don't know everything about the universe, yet.  Then it's not as amazing because we know that new things will come up that we don't really understand the way we normally understand things.

Ok, so where did my Fosters go...

With these sorts of replies, I don't see that people are serious about the subject.


I agree that the model of one phenomenon exhibits differences from the model of a different phenomenon.
Why would anyone expect it to be otherwise ?
But it is also true that there is often commonality between pairs of models that allow one to be used as analogs for the other  - in the right circumstances.

For instance both classical wave theory and QM have an uncertainty principle.
The classical version starts with Parseval's theorem and several  pages of maths later ends with the conclusion that   Δt Δω  ≥  1/2,
when considering non recurrent waveforms.

So here we can see some commonality between classical and quantum.

However in the classical model the wave variable, φ,  has a physical meaning in out material universe.

On the other hand the wave variable in quantum theory does not correspond to any physical variable, certainly not probability as some proclaim.
In fact in only takes a few lines of maths to prove that Ψ cannot represent probability which is positive definite, while Ψ has positive and negative parts.

Nevertheless quantum theory cannot do without classical underpinning since the forces and energies involved are classical quantities ( non relativistic or relativistic as appropriate).

Another difference often overlooked is that classical analysis looks for solutions to the wave or other equations since its variable, φ, represents some material world quantity.

Quantisation looks for the zeros of the solutions to the corresponding quantum equations to meet energy requirements.

Hello again,

Well I am not sure what you are trying to say here.  First it sounds like some sort of mocking, which for one is untrue as told by the number of replies, but you don't need to mock anybody out you just need to state your case.

Anyway, it sounds like you are taking an apple and a pear and saying that they both grow on trees.  Yes they both have that in common, but it's a very vague commonality.  Now if you said (and if it was true) that pears have the same seeds as apples, THAT would be a very interesting commonality which would take some explaining.  By "same" I mean exactly the same, no difference whatsoever.

START_QUOTE
On the other hand the wave variable in quantum theory does not correspond to any physical variable, certainly not probability as some proclaim.
END_QUOTE

Where are you getting this information from?  What are you considering the "wave variable" to be?
The wavefunction is a probability function.  Check out "probability amplitudes" of the wavefunction.  Check out the square of that also.
Also check out the Born rule.

Actually I wasn't mocking anyone.

I was, however, feeling a trifle aggrieved that whilst I carefully considered and responded to points put by others,
Some others seem to be cherry picking my words out of context in order to simply tell me I am wrong, without any explanation or backup.

You for instance did this with your line about probability in the post I just quoted, in response to my claim, which included reasoning.

I seriously ask you to look at my Rochester experiment in the preceding  post and add your prediction.

[showman]

I read the reference from Dr Kinsler and it seems to me that he was saying more or less what I was saying, though he also addressed EM topics not relevant to radio waves.

He's talking about exactly what photons are and you said "According to duality, photons and radio waves are the same thing.", therefore according to duality, he's talking about radio waves.

So imagine you have a photon source that can produce from one single photon to many many photons at the turn of a calibrated dial.
Also you have a detector capable of detecting from one single photon to many many nearly coincident ones.

So you aim the source, set to single photon mode, at the detector and confirm that your detector reliably detects the transmitted photon.
Now move the detector slightly off beam and then further off beam, recording what you see.

Now please predict what happens ?

Ok you said you read that link, but seemed to miss the whole point. If you say "single photon" you need to specify your boundary conditions, i.e. what are the modes that you quantized. Also, is it a true single photon source or something like attenuated laser, which does not produce single photon states and can be handled semiclassically. If it is a true single photon source, does it produce single mode states or multi-mode states or perhaps something completely different. Depending on the answers, the result can be a lot of things.

[David Hess]

FINALLY: A Proof that Particles Take All Paths At Once? [Sabine]

https://youtu.be/A2ImadKWaHA?si=4ffcu1X6BcnuooXB

TLDW: 9/10 on Bullshit Meter

[studiot]

He's talking about exactly what photons are and you said "According to duality, photons and radio waves are the same thing.", therefore according to duality, he's talking about radio waves.

Yes, I'm glad you agree that radio waves are part of the EM spectrum, though many of us use the word 'light' and EM spectrum interchangeably.

As I read it , Kinsler was talking about several things and never actually stated words to the effect "A photon is ... ".
What he actually said was

I promise not to come up with my own patented theory of
> light,

Further the article was entitled "Re Photon Lengths"

And yes he discussed boundary conditions, something I am keen on, that so often get overlooked.

Ok you said you read that link, but seemed to miss the whole point. If you say "single photon" you need to specify your boundary conditions, i.e. what are the modes that you quantized. Also, is it a true single photon source or something like attenuated laser, which does not produce single photon states and can be handled semiclassically. If it is a true single photon source, does it produce single mode states or multi-mode states or perhaps something completely different. Depending on the answers, the result can be a lot of things.

This seems to me to be classic evasion tactics.

You have been told that the experiment provides a photon source and a suitable detector for whatever photons are emitted, which is demonstrated to detect those photons at the start of the experiment.

Very simple.

Since you wish to quibble let us ask what do you see if you release 10^2 photons, 10^6  photons etc ?

The full experiment did exactly that.

I just simplified it.

Oh and I offer a simplified definition of a photon.  The shortest (in time) possible pulse of light.

[showman]

Yes, I'm glad you agree that radio waves are part of the EM spectrum, though many of us use the word 'light' and EM spectrum interchangeably.

As I read it , Kinsler was talking about several things and never actually stated words to the effect "A photon is ... ".
What he actually said was

I promise not to come up with my own patented theory of
> light,

The title is literally "What is a Photon?" and the second sentence starts with "We define photons like this:", so why are you lying? And what follows is really the agreed upon definition of photons, that's why he says he does not come up with anything on his own, just recites the known theory. And basically the same explanation, but in much more detail, is given in the book I referred to.

This seems to me to be classic evasion tactics.

Oh and I offer a simplified definition of a photon.  The shortest (in time) possible pulse of light.

A shortest possible pulse of light is not a photon and it is not evasion if you don't provide any details that are actually important.

Ok I can then come up with my own. Since you mentioned "beam", I guess it might be a laser. Laser, whether it is attenuated below single photon level or not, is essentially a classical light source for which you don't need quantization of the EM field i.e. photons at all. Also I don't see the point of moving a detector. I can put a camera there so I'll detect everything. Next, assuming gaussian beam, and long enough time to integrate the single detections, you will just get an image of the gaussian beam profile. If you increase the intensity, you get the same image in a shorter time. Or equivalently a brighter image in the same time, but it's still gaussian.

Again, it says nothing about photons, especially single photons as such, because attenuated coherent state is still coherent, i.e. quasi-classical. I quote from the Grynberg book:

Note that the above result remains true even if the expected number of photons N is
well below unity. Now it can be shown that a light pulse that has been highly attenuated
by passing through an absorbent material gives precisely a multimode quasi-classical state,
where N can assume a value much less than unity. Such a state is radically different from
a one-photon state, since the inequalities (5B.45) or (5B.55) are not violated. It has been
checked that the inequality (5B.55) remains true even for an expected number of photons
per pulse equal to N = 10−2 .2 It is therefore incorrect to claim that a highly attenuated
beam is made up of single photons.

The properties of a quasi-classical wave packet can thus be interpreted using a classical
model of the electromagnetic field.

[studiot]

Yes, I'm glad you agree that radio waves are part of the EM spectrum, though many of us use the word 'light' and EM spectrum interchangeably.

As I read it , Kinsler was talking about several things and never actually stated words to the effect "A photon is ... ".
What he actually said was

I promise not to come up with my own patented theory of
> light,

The title is literally "What is a Photon?" and the second sentence starts with "We define photons like this:", so why are you lying? And what follows is really the agreed upon definition of photons, that's why he says he does not come up with anything on his own, just recites the known theory. And basically the same explanation, but in much more detail, is given in the book I referred to.

This seems to me to be classic evasion tactics.

Oh and I offer a simplified definition of a photon.  The shortest (in time) possible pulse of light.

A shortest possible pulse of light is not a photon and it is not evasion if you don't provide any details that are actually important.

Ok I can then come up with my own. Since you mentioned "beam", I guess it might be a laser. Laser, whether it is attenuated below single photon level or not, is essentially a classical light source for which you don't need quantization of the EM field i.e. photons at all. Also I don't see the point of moving a detector. I can put a camera there so I'll detect everything. Next, assuming gaussian beam, and long enough time to integrate the single detections, you will just get an image of the gaussian beam profile. If you increase the intensity, you get the same image in a shorter time. Or equivalently a brighter image in the same time, but it's still gaussian.

Again, it says nothing about photons, especially single photons as such, because attenuated coherent state is still coherent, i.e. quasi-classical. I quote from the Grynberg book:

Note that the above result remains true even if the expected number of photons N is
well below unity. Now it can be shown that a light pulse that has been highly attenuated
by passing through an absorbent material gives precisely a multimode quasi-classical state,
where N can assume a value much less than unity. Such a state is radically different from
a one-photon state, since the inequalities (5B.45) or (5B.55) are not violated. It has been
checked that the inequality (5B.55) remains true even for an expected number of photons
per pulse equal to N = 10−2 .2 It is therefore incorrect to claim that a highly attenuated
beam is made up of single photons.

The properties of a quasi-classical wave packet can thus be interpreted using a classical
model of the electromagnetic field.

Why am I lying ?

Wow

What an accusation when this is what i see when clicking on the link supplied by you.




There is the title, writ very large and very bold in Headline or Title format.


Re: Photon lengths.


Further down in the middle of some text it does indeed ask the question what is a photon, but that is part of a discussion or presentation, not the title of it.

You owe me an apology.

[radiolistener]

Quantum mechanics does not arise for this type of wave system, although it obeys resonance curves and requirements.

That is not correct. QM still applies to a water-wave system, quantum effects are simply utterly negligible at the macroscopic scale, so classical fluid mechanics is an extremely good approximation. The same applies to electromagnetic waves - a macroscopic EM wave can be described extremely well by classical Maxwell equations, while the underlying field also has a quantum description.

So the important distinction is not that water waves are "classical" while EM waves are "quantum", but that in the regimes we normally observe them, the relevant quantum effects are negligible for water waves and often negligible for ordinary macroscopic EM waves.

EM waves are quite different in that there is no pre-existing medium and that the medium has no mass.

The statement that the EM "medium" has no mass is a conceptual error.

An individual photon has zero invariant mass, but a system of several photons can have nonzero invariant mass depending on its total energy and momentum.

[Marco]

I'm not pretending anything.

I was talking more in general, maybe I should have used "one" instead.

Talking about radiowaves like I and I suspect most of us here think about them (classical solutions to Maxwell equations) as part of the wave/particle duality is a bit too archaic. The modern duality is inside QM entirely, so adding the fully classical view makes it more like a triality.

[showman]

There is the title, writ very large and very bold in Headline or Title format.

Re: Photon lengths.

Have you ever seen a mailing list archive?
This page is within a mailing list thread that someone else started with a name of "Photon lengths", same way RoGeorge started this forum thread with title "Radio waves propagate spherically, how comes the photon moves in a straight line". That does not mean every post here is about that specific sentence.

In order to understand "photon length", you need to first understand what a photon even is. So Dr. Kinsler replies in that thread and adds to it his work in progress text the title of which is "What is a Photon?" in which he explains exactly, albeit with very little mathematics, what a photon is. Again, the explanation matches what is in Grynberg's quantum optics textbook which also adds the mathematical framework, but the qualitative content is the same.

You on the other hand keep claiming that he does not really tell what a photon is or that he just "asks what it is", which again implies he does not tell it or does not even know or is being philosophical.
Therefore yes, you are lying about what Kinsler actually said. Not even that, since you keep repeating it, it even starts to turn into gaslighting. Not going to apologize for that. In fact the one who should apologize is you, and not to me, but to Dr Kinsler.

[paulca]

Water waves.  Or any wave.  The point the metaphor I recall was making when it asked the question, "Where is the wave?" was that it's a non-nonsensical question for a wave.  A wave does not have a set of coordinates.  You can characterise the wave sure, but not actually answer "Where is the wave?", because the wave just is. A travelling continuum.  It can be inspected at a "point" and you can define that "point" however you wish, but when you do that, you are now reasoning a point, not a wave.

The more you constrain the wave towards being a point, the more it behaves like a point in our measurements.  It still doesn't tell you what the full wave continuum is doing or where it is though.

Hissenberg uncertainty principle and others all seem to circle around the same dualities of measurement.  Once you "fix" a few key variables to get an answer, the answer is somehow changed because of the question you asked.  Release those variables and it goes back to "ill-defined" or "undefinable".  Constrain it with different variables, you get a different answer.  Constrain it with the same variables and do multiple tests and often get different answers.  Yet with strong mathematical accuracy QM makes predictions of what will happen in X number of cases when you constrain some variables.  That has enough scientific and industrial applications most people stopped asking "Why?" and just roll with the numbers.

If that layman metaphor holds.  A photon is what you get if you constrain the EM wave into a point by asking "Where is it?"