<html><head></head><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yui_3_16_0_ym19_1_1485662868797_2946"><span id="yui_3_16_0_ym19_1_1485662868797_3029">I do. And it explains diffraction.</span></div><div id="yui_3_16_0_ym19_1_1485662868797_2946"><span id="yui_3_16_0_ym19_1_1485662868797_3030">Hodge</span></div> <div class="qtdSeparateBR"><br><br></div><div class="yahoo_quoted" style="display: block;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div dir="ltr"><font size="2" face="Arial"> On Saturday, January 28, 2017 7:12 PM, Dr Grahame Blackwell <grahame@starweave.com> wrote:<br></font></div> <br><br> <div class="y_msg_container"><div id="yiv6089736424">
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<div><font color="#000080" size="2" face="Arial">Dear All,</font></div>
<div><font color="#000080" size="2" face="Arial">[Notably Chandra &
Chip],</font></div>
<div><font color="#000080" size="2" face="Arial"></font> </div>
<div><font color="#000080" size="2" face="Arial">I'm having a bit of a problem over
this question of: 'How does a photon carry momentum'? (or similar
words.)</font></div>
<div><font color="#000080" size="2" face="Arial">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.</font></div>
<div><font color="#000080" size="2" face="Arial">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.</font></div>
<div><font color="#000080" size="2" face="Arial">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).</font></div>
<div><font color="#000080" size="2" face="Arial">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.</font></div>
<div><font color="#000080" size="2" face="Arial"></font> </div>
<div><font color="#000080" size="2" face="Arial">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?</font></div>
<div><font color="#000080" size="2" face="Arial">(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.)</font></div>
<div><font color="#000080" size="2" face="Arial"></font> </div>
<div><font color="#000080" size="2" face="Arial">Thanks in anticipation,</font></div>
<div><font color="#000080" size="2" face="Arial">Grahame</font></div></div></div><br>_______________________________________________<br>If you no longer wish to receive communication from the Nature of Light and Particles General Discussion List at <a ymailto="mailto:jchodge@frontier.com" href="mailto:jchodge@frontier.com">jchodge@frontier.com</a><br><a href="<a href="http://lists.natureoflightandparticles.org/options.cgi/general-natureoflightandparticles.org/jchodge%40frontier.com?unsub=1&unsubconfirm=1" target="_blank">http://lists.natureoflightandparticles.org/options.cgi/general-natureoflightandparticles.org/jchodge%40frontier.com?unsub=1&unsubconfirm=1</a>"><br>Click here to unsubscribe<br></a><br><br><br></div> </div> </div> </div></div></body></html>