sci.physics.particle

On 17 Mar, 01:04, BradGuth wrote:
> On Mar 16, 1:41 pm, The Speaking Clock
> wrote:
>
>
>
>
>
> > On 16 Mar, 20:30, BradGuth wrote:
>
> > > On Mar 16, 9:14 am, Tom Roberts wrote:
>
> > > > The Speaking Clock wrote:
> > > > > On 15 Mar, 08:57, Pentcho Valev wrote:
> > > > >> [... his usual nonsense]
>
> > > > > Would the speed of light be a non wiggly constant at the very edge=
of
> > > > > the universe - bending around it?
>
> > > > The speed of light is a constant, c, for any LOCAL measurement anywh=
ere
> > > > in the universe. I guess that includes "non wiggly". It also include=
s
> > > > essentially all measurements of light speed here on earth. At least =
that
> > > > is what GR predicts, and there are no observations that contradict i=
t.
>
> > > > =A0 =A0 =A0 =A0 [Ignore Valev when he brings up Pound-Rebka and simi=
lar
> > > > =A0 =A0 =A0 =A0 =A0experiments -- they do not measure speed.]
>
> > > > But if you want to see light "bending around the universe" then that=

> > > > would certainly require a non-local path, and there's no solid
> > > > prediction of the result (given the uncertainties in the physical
> > > > situation you have in mind).
>
> > > > It is rather difficult to perform a non-local measurement of the spe=
ed
> > > > of light, but it has been done by sending radar waves across the sol=
ar
> > > > system to reflect back from mars and venus. By measuring the round-t=
rip
> > > > delay repeatedly over several years, and fitting to the planetary
> > > > orbits, one can deduce the round-trip speed of light for these paths=
.
> > > > That speed varies, depending on how close to the sun the path passes=
;
> > > > look up "Shapiro time delay". The results are in excellent agreement=

> > > > with the predictions of GR.
>
> > > > =A0 =A0 =A0 =A0 Some people claim this is due to the solar atmospher=
e.
> > > > =A0 =A0 =A0 =A0 They are wrong: by doing this for multiple wavelengt=
hs the
> > > > =A0 =A0 =A0 =A0 effect of the solar atmosphere can be identified, an=
d is
> > > > =A0 =A0 =A0 =A0 found to be negligible. Of course it would be highly=

> > > > =A0 =A0 =A0 =A0 unlikely that such a different effect could mimic th=
e GR
> > > > =A0 =A0 =A0 =A0 dependence on path. Indeed, measurements using pulsa=
rs
> > > > =A0 =A0 =A0 =A0 agree with the GR predictions for paths that never g=
o
> > > > =A0 =A0 =A0 =A0 inside earth's orbit, and we know what the solar
> > > > =A0 =A0 =A0 =A0 atmosphere is out here.
>
> > > > Tom Roberts
>
> > > But photons clearly represent mass, thus the solar atmosphere of
> > > photons does offer mass for other passing photons to interact with.
> > > . -BradGuth- Hide quoted text -
>
> > > - Show quoted text -
>
> > My physics friend says - "what about the underlying noise of the
> > universe caused by the discrete nature of the photon/s in time, and
> > how does that contribute to the total 1/f energy of the universe?"
>
> > And then he changed the subject because light speed and it's constant
> > interacting with what he talked about is something to do with space
> > travel and I'm a buddhist. =A0lol. =A0Although - this is just my surmise=
;)
>
> Don't exclude anything unless you know for certain otherwise.
> . - Brad Guth- Hide quoted text -
>
> - Show quoted text -

*nodding like the churchill dog*

My physics friend also says that photons have a *theoretical* mass.
Whatever that means. To a buddhist - everything looks largely
theoretical. :)

Physists don't agree on anything - not the shape of the universe,
whether light has a constant, why it bends. Ask a simple question -
get a complex argument. Ah well - as long as people have fun. :)