🚀 go-pugleaf

In article <12950067@hpspdla.spd.HP.COM>, ric@hpspdla.spd.HP.COM (Ric Peregrino) writes...
> 
>Thanks for the responses,
> 
>Regarding electron positron annihilation John Baez writes:
> 
>>Sorry, photons only have 2 spin states, 1 and -1.
>>That's because they are massless.
> 
>Don't be sorry John. I thank you and ask:
> 
>How does masslessness lead to no spin 0 photons? If this is too deep,
>then a reference would suffice.

That's a different question than the one John answered.  Photons have 
spin 1 - this has nothing to do with mass.  Photons may also be put into
a state in which the expectation of the spin along a chosen axis is zero.
This is also independent of mass.

But a single photon has only two spin polarizations.  This affects
how it behaves in important ways - and *is* the result of the photon's
masslessness.

-Scott
--------------------
Scott I. Chase			"The question seems to be of such a character
SICHASE@CSA2.LBL.GOV		that if I should come to life after my death
				and some mathematician were to tell me that it
				had been definitely settled, I think I would
				immediately drop dead again."      - Vandiver