[General] On photon momentum

Dr Grahame Blackwell grahame at starweave.com
Sat Jan 28 16:11:58 PST 2017


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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.natureoflightandparticles.org/pipermail/general-natureoflightandparticles.org/attachments/20170129/0350589a/attachment.htm>


More information about the General mailing list