sci.physics.particle

BradGuth wrote:
> On Mar 16, 9:14 am, Tom Roberts wrote:
>> [about Shapiro time delay]
>
> But photons clearly represent mass,

One must be very careful when attempting to say something like this, and
the photon itself clearly has zero mass -- that is part of the
definition of "photon". I have no idea what you mean by "represent" here.


> thus the solar atmosphere of
> photons does offer mass for other passing photons to interact with.

When we say "solar atmosphere" we don't mean photons at all. We mean the
usual sort of things that make up an atmosphere: gases and particulates
floating in the gases. The total mass of the solar atmosphere is utterly
negligible compared to the mass of the sun (just as it is for earth).

I mentioned the solar atmosphere because some people think the Shapiro
time delay is due to it (such an atmosphere has an altitude-varying
index of refraction, which _could_ behave like the Shapiro time delay).
It's just that actual measurements of the solar atmosphere and its
properties completely refute that claim.


Tom Roberts