<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=utf-8"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman",serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p
{mso-style-priority:99;
mso-margin-top-alt:auto;
margin-right:0in;
mso-margin-bottom-alt:auto;
margin-left:0in;
font-size:12.0pt;
font-family:"Times New Roman",serif;}
p.MsoAcetate, li.MsoAcetate, div.MsoAcetate
{mso-style-priority:99;
mso-style-link:"Balloon Text Char";
margin:0in;
margin-bottom:.0001pt;
font-size:8.0pt;
font-family:"Tahoma",sans-serif;}
p.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph
{mso-style-priority:34;
margin-top:0in;
margin-right:0in;
margin-bottom:0in;
margin-left:.5in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman",serif;}
span.BalloonTextChar
{mso-style-name:"Balloon Text Char";
mso-style-priority:99;
mso-style-link:"Balloon Text";
font-family:"Tahoma",sans-serif;}
p.msonormal0, li.msonormal0, div.msonormal0
{mso-style-name:msonormal;
mso-style-priority:99;
mso-margin-top-alt:auto;
margin-right:0in;
mso-margin-bottom-alt:auto;
margin-left:0in;
font-size:12.0pt;
font-family:"Times New Roman",serif;}
span.EmailStyle22
{mso-style-type:personal;
font-family:"Times New Roman",serif;
color:#1F497D;}
span.EmailStyle23
{mso-style-type:personal;
font-family:"Times New Roman",serif;
color:#20188C;
font-weight:normal;
font-style:normal;
text-decoration:none none;}
span.EmailStyle24
{mso-style-type:personal;
font-family:"Times New Roman",serif;
color:#993366;}
span.EmailStyle25
{mso-style-type:personal;
font-family:"Times New Roman",serif;
color:#20188C;
font-weight:normal;
font-style:normal;
text-decoration:none none;}
span.EmailStyle26
{mso-style-type:personal;
font-family:"Times New Roman",serif;
color:#003300;}
span.EmailStyle27
{mso-style-type:personal;
color:black;}
span.EmailStyle28
{mso-style-type:personal;
color:black;}
span.EmailStyle29
{mso-style-type:personal;
font-family:"Times New Roman",serif;
color:olive;}
span.EmailStyle30
{mso-style-type:personal;
color:black;}
span.EmailStyle31
{mso-style-type:personal;
font-family:"Calibri",sans-serif;
color:windowtext;}
span.EmailStyle32
{mso-style-type:personal;
font-family:"Calibri",sans-serif;
color:#1F497D;}
span.EmailStyle33
{mso-style-type:personal;
font-family:"Calibri",sans-serif;
color:#1F497D;}
span.EmailStyle34
{mso-style-type:personal;
color:black;}
span.EmailStyle35
{mso-style-type:personal;
font-family:"Times New Roman",serif;
color:teal;}
span.EmailStyle36
{mso-style-type:personal;
color:black;}
span.EmailStyle38
{mso-style-type:personal-reply;
color:black;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='color:black'>Hi Dr. Grahame Blackwell<o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'>I too am finding little use in this discussion. <o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'>For me the evidence that a photon carries momentum is quite compelling.<o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'>Not only the evidence from the reaction of matter to light, but also the clear and definable results we can get for the mass of a particle if propagating energy carries momentum. And if we conclude that propagating energy in a particle has momentum, then it is likely that any propagating energy also has momentum.<o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'>I get the feeling you don’t like the concept of momentum in light. While it may be interesting to suggest that momentum doesn’t happen until the light hits a massive particle, the results of that assumption are at odds with the creation of mass from energy.<o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'>I have no problem with you holding the opinion that light does not carry momentum. I just can’t accept that premise myself without a host of strong arguments which illustrate how the pieces can fit if propagating energy has no momentum. Those arguments would of course need to be simpler and more robust than the alternative.<o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'>So unless you have such a complete explanation I am finished with this momentum debate.<o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'>Chip<o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> General [mailto:general-bounces+chipakins=gmail.com@lists.natureoflightandparticles.org] <b>On Behalf Of </b>Dr Grahame Blackwell<br><b>Sent:</b> Monday, January 30, 2017 9:45 AM<br><b>To:</b> Nature of Light and Particles - General Discussion <general@lists.natureoflightandparticles.org><br><b>Subject:</b> Re: [General] On photon momentum<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>Thanks Chip,</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>But you <strong><span style='font-family:"Arial",sans-serif'>still</span></strong> haven't answered my question!</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>Understanding momentum isn't a problem - the issue is getting a clear unequivocal definition that relates to photons - <strong><span style='font-family:"Arial",sans-serif'>without</span></strong> it being a circular definition.</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>I'm equally well able to look up a textbook as anyone else; as I said before, such definitions refer to massive objects - which light isn't. So your first sentence doesn't move the issue one step forward (I am of course extremely well conversant with the concept of impulse, which is reciprocally defined in terms of momentum - this doesn't actually add anything).</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><div><p class=MsoNormal><strong><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>Note that I'm not asking this question because I'm naive scientifically - on the contrary, I'm asking it because I believe that the scientific community as a whole is using a concept that they don't actually understand and are glossing over the fact that they don't understand it by trotting out the same old equations without clearly defining the terms in those equations. In this I'm attempting to prod physics into moving forward rather than going round & round in the same old circles.</span></strong><o:p></o:p></p></div></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>Yes of course p=Ft is a more appropriate expression (not term) for momentum of a photon - so now can you identify what F and t are, quantatively, for a photon? I.e. can you define the force applied by a photon and the duration for which that force is applied - without simply referring back to momentum or impulse, thus making it a circular definition? [Personally I think it should be more generally expressed in terms of integral(p dt) , since I know of no evidence that the 'force' applied to a particle by a photon is constant - indeed it's unlikely to be, if the particle is accelerating over that duration.] I don't know of <strong><span style='font-family:"Arial",sans-serif'>any</span></strong> source for such information, indeed I question whether that information has ever been experimentally verified (or even whether it could).</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><strong><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>Again</span></strong><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'> (for the last time - I'm beginning to lose the will to live on this one!): can you, or anyone, provide a clear-cut definition for momentum that can be directly applied to a photon (rather than implicitly applied to a photon by association with impulse - which itself is implied by the transfer of momentum - which is ... ad infinitum). If such a definition is not possible, then I (again) question the very concept as an intrinsic property of a photon. If you need more than three lines for your definition then it's unlikely to be a definition and more likely to be a mathematical rationale.</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><strong><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>As Richard Feynman famously said: "If you can't explain a concept in terms that a layman [or woman] can understand, then maybe you need to think very carefully about whether you truly understand it yourself." </span></strong><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>I'm not a lay-person, scientifically speaking - so if there <strong><span style='font-family:"Arial",sans-serif'>is</span></strong> a comprehensible definition, then I think I should hopefully be able to understand it.</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>In hope (but steadily fading...),</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>Grahame</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal>----- Original Message ----- <o:p></o:p></p></div><blockquote style='border:none;border-left:solid navy 1.5pt;padding:0in 0in 0in 4.0pt;margin-left:3.75pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt'><div><p class=MsoNormal style='background:#E4E4E4'><b><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>From:</span></b><span style='font-size:10.0pt;font-family:"Arial",sans-serif'> <a href="mailto:chipakins@gmail.com" title="chipakins@gmail.com">Chip Akins</a> <o:p></o:p></span></p></div><div><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>To:</span></b><span style='font-size:10.0pt;font-family:"Arial",sans-serif'> <a href="mailto:general@lists.natureoflightandparticles.org" title="general@lists.natureoflightandparticles.org">'Nature of Light and Particles - General Discussion'</a> <o:p></o:p></span></p></div><div><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>Sent:</span></b><span style='font-size:10.0pt;font-family:"Arial",sans-serif'> Monday, January 30, 2017 1:38 PM<o:p></o:p></span></p></div><div><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>Subject:</span></b><span style='font-size:10.0pt;font-family:"Arial",sans-serif'> Re: [General] On photon momentum<o:p></o:p></span></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal><span style='color:black'>Dr Grahame Blackwell<o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'>Textbook definition.<o:p></o:p></span></p><p class=MsoNormal><span style='color:black'>[Conventional momentum is the product of mass and velocity of a massive object p=mv. Dimensionally momentum is equivalent to Impulse, which is defined force through time. So p=mv and p=Ft]. <o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'>For a massless wave in space p=Ft is the more appropriate term. <o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'>Nothing strange or ill-defined about momentum. It is real, and easy to understand. <o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'>Photons do not have mass in the conventional sense, but they do display the property of momentum (impulse) when they interact with matter. <o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'>Why try to understand the momentum of a photon? Simple. If waves propagating through space have momentum, and they also have momentum when confined to form fermions, then we have the reason why E=mc^2, and we have the reason for inertial mass.<o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'>My reasoning for exploring this…<o:p></o:p></span></p><p class=MsoNormal><span style='color:black'>If we don’t have a clear definition of an item which seems to be responsible for properties we observe, then we should explore the possibilities, rather than just forming opinions without further inquiry. <o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:black'>Chip<o:p></o:p></span></p><p class=MsoNormal><span style='color:black'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> General [<a href="mailto:general-bounces+chipakins=gmail.com@lists.natureoflightandparticles.org">mailto:general-bounces+chipakins=gmail.com@lists.natureoflightandparticles.org</a>] <b>On Behalf Of </b>Dr Grahame Blackwell<br><b>Sent:</b> Monday, January 30, 2017 6:15 AM<br><b>To:</b> Nature of Light and Particles - General Discussion <<a href="mailto:general@lists.natureoflightandparticles.org">general@lists.natureoflightandparticles.org</a>><br><b>Subject:</b> Re: [General] On photon momentum<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>Dear Chandra, Chip, John D, everyone,</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>I really appreciate all your responses, truly I do.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>BUT - <strong><span style='font-family:"Arial",sans-serif'>NOBODY appears to have answered, or even addressed, my question.</span></strong></span><o:p></o:p></p></div><div><p class=MsoNormal><strong><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>(With the exception of Chandra, Vladimir and John D, who actually question the fundamental premise - as I do.)</span></strong><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><strong><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>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).</span></strong><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><strong><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>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.</span></strong><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><strong><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>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.</span></strong><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'> 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 <strong><span style='font-family:"Arial",sans-serif'>consequence</span></strong> of energy.</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>[So, Chandra, contrary to your first response, I actually DO like your opinion! It's the only one that makes sense to me.]</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>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).</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><strong><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>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?!</span></strong><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><strong><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>Again: any offers?</span></strong><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>Best regards to all,</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:navy'>Grahame</span><o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p></div></blockquote></div></body></html>