[General] On photon momentum

Chip Akins chipakins at gmail.com
Mon Jan 30 07:17:00 PST 2017


Hi Dr Grahame Blackwell

 

Some additional thoughts…

 

According to Maxwell’s equations, the energy density of electric and magnetic fields e and b is (e2 + b2)/(8p) and the momentum density is (e x b)/(4pc). Thus in the case of radiation (when e and b are equal and orthogonal) the energy density is E = e2/(4p) and the momentum density is p = e2/(4pc), so we have the relation p = E/c.  Therefore we can show that light pulses of total energy E confined in a particle, contribute E/c2 to the inertial mass of the particle.

 

Chip

 

From: General [mailto:general-bounces+chipakins=gmail.com at lists.natureoflightandparticles.org] On Behalf Of Dr Grahame Blackwell
Sent: Monday, January 30, 2017 6:15 AM
To: Nature of Light and Particles - General Discussion <general at lists.natureoflightandparticles.org>
Subject: Re: [General] On photon momentum

 

Dear Chandra, Chip, John D, everyone,

 

I really appreciate all your responses, truly I do.

BUT - NOBODY appears to have answered, or even addressed, my question.

(With the exception of Chandra, Vladimir and John D, who actually question the fundamental premise - as I do.)

 

My question was a request for a 'text-book' style DEFINITION OF MOMENTUM APPLICABLE TO PHOTONS (not just how it's contained, how it propagates, whatever).

 

Without having a clear definition of what momentum IS (in a form applicable to photons), IMO it's utterly meaningless to try and explain/discuss/dispute how it propagates or anything else about it.  I don't see such a definition in ANY of the flood of emails following my question.

 

If the answer is that no such text-book definition exists, then we have to question whether momentum itself exists as an intrinsic property of momentum.  In this I'm at one with Chandra that momentum is rather a characteristic that emerges in reactions involving photons or massive particles - nothing more or less.  I'm also with John D that momentum is well characterised by the motion of a wave, and that energy & momentum aren't two different things - momentum is an emergent consequence of energy.

 

[So, Chandra, contrary to your first response, I actually DO like your opinion!  It's the only one that makes sense to me.]

 

I'd further agree 100% with Chandra and Vladimir that 'energy flow' through the ether is rather simply a self-propagating excitation of that ether (Chandra's CTF, Vladimir's node array) - like plucking a (3-dimensional) guitar string and seeing the vibration travel along the string: the vibration, the photon, the material particle, is NOT a physical 'thing' in its own right, it's simply a state-of-being of the ether, one that is self-sustaining (as a point of detail, in my early book I liken a material particle to a whirlpool in a stream - it's not the water, it's the self-sustaining pattern IN the water).

 

So unless we have a clear definition of momentum applicable to photons, I see absolutely no point in trying to explain how it happens - how can you discuss how something happens when you can't even define what it is?!

 

Again: any offers?

 

Best regards to all,

Grahame

----- Original Message ----- 

From: Roychoudhuri, Chandra <mailto:chandra.roychoudhuri at uconn.edu>  

To: Nature of Light and Particles - General Discussion <mailto:general at lists.natureoflightandparticles.org>  

Sent: Sunday, January 29, 2017 2:23 AM

Subject: Re: [General] On photon momentum

 

Hi Chip: Again, my current state of thinking is that even material particles, and hence electrons, do not possess the intrinsic property, we call MOMENTUM. This is unlike the ENERGY contained in its state of excitation (which is the cause of its existence). When v = 0, the momentum, mv, is zero. In Milikan’s oil drop experiment, he made the electron-holding oil drop stationary; so the whole drop, with the electron, had zero velocity; and hence zero momentum. Thus momentum is not an intrinsic property, even for material particles. The momentum-property becomes emergent and measurable only when one kinetic entity transfers part of its kinetic energy to increase the kinetic velocity of another particle.

 

Chandra.

 

From: General [mailto:general-bounces+chandra.roychoudhuri=uconn.edu at lists.natureoflightandparticles.org] On Behalf Of Chip Akins
Sent: Saturday, January 28, 2017 8:54 PM
To: 'Nature of Light and Particles - General Discussion'
Subject: Re: [General] On photon momentum

 

Hi Chandra

 

I like your thoughts on this subject.  

 

But one issue is giving me pause.  That is simply the need to have momentum circulating in the electron in order for it to possess inertial mass. And therefore, if momentum is created by the energy within the electron as it propagates (circulates) then it seems likely that momentum is also generated by the wave in space propagating linearly. Of course this may not be the case. But it seems the Occam’s preference given the situation. 

 

But it could be that momentum is only created by the motion of energy when confined such as in the electron, and that momentum is imparted to that structure simply because energy is added when it reacts with EM radiation. I have not preferred this solution because it seems more complex, and less likely, if the laws of physics are uniform for propagating energy.

 

Chip

 

From: General [mailto:general-bounces+chipakins=gmail.com at lists.natureoflightandparticles.org] On Behalf Of Roychoudhuri, Chandra
Sent: Saturday, January 28, 2017 7:08 PM
To: Nature of Light and Particles - General Discussion <general at lists..natureoflightandparticles.org <mailto:general at lists.natureoflightandparticles.org> >
Subject: Re: [General] On photon momentum

 

Dear Grahame: 

You would not like my opinion! And, I may change my opinion as I grow up learning from others!

 

As of now, my personal views are very very different from the mainstream assertions about, “indivisible photon”, its “momentum”, “spin” etc.

To me, they are not intrinsic property of EM waves.

They appear as measurable properties of detecting materials as they interact (respond) to the incident EM wave packets and undergo various physical changes while absorbing energy out of the propagating EM.

 

For example, at the instant of emission, we certainly have a discrete quantity of energy (hv) that is released as a result of some quantum transition. That released energy “plucks” the Complex Tension Field (CTF) [or, the plenum , the ether, etc.]. The result of that “plucking” is the emergence of an EM wave packet with the frequency “v”; which then propagates away perpetually as an excitation of the CTF as long as far as the CTF exists. 

 

“Filtered” polarized light, interaction with anisotropic material medium will show preferential directional movement implying “angular momentum transfer”, which we have learned to explain as “photon” having “Angular Momentum”.

 

Chandra.

 

From: General [mailto:general-bounces+chandra.roychoudhuri=uconn.edu at lists.natureoflightandparticles.org] On Behalf Of Dr Grahame Blackwell
Sent: Saturday, January 28, 2017 7:12 PM
To: Nature of Light and Particles - General Discussion <general at lists..natureoflightandparticles.org <mailto:general at lists.natureoflightandparticles.org> >
Subject: [General] On photon momentum

 

Dear All,

[Notably Chandra & Chip],

 

I'm having a bit of a problem over this question of: 'How does a photon carry momentum'? (or similar words.)

It seems to me that in order to even beginning to address this question, one needs a clear definition of 'momentum' that's applicable to the momentum carried by a photon.

I may be looking in the wrong places (if so please advise), but the only definitions of momentum that I can find either refer to 'mass' or refer to some other phenomenon which in turn refers to momentum - i.e. circular references.

If I'm going to figure, or be persuaded, how a photon carries momentum I first need to know what momentum IS in respect of a photon (yes, I know it's E/c, that's a measure it's not a definition).

Of course I'm aware of the paper "Light is heavy", but I don't feel it's appropriate just to extract from that some sort of mass-equivalence of a photon.  If we do, we get the result that 'm'=E/c^2, so 'm'c = E/c - gives the right result, but appears to be some sort of convoluted self-confirmation (i.e. a circular argument dressed up in fancy clothes).  It certainly doesn't DEFINE a photon's momentum, just evaluates it.

 

Does anyone have a convincing definition of momentum that's applicable to a photon?  One that can be used as a firm basis for theorising?

(I'd be glad if colleagues didn't use this as an excuse to yet again present their own personal theory/model - I'm looking for a definition that would be agreed by all, or at least most, physicists.)

 

Thanks in anticipation,

Grahame

  _____  

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