sci.physics.particle

On Feb 26, 2:18=A0am, va...@cox.net wrote:
> On Feb 25, 10:03=A0pm, pmb wrote:
>
>
>
>
>
> > On Feb 25, 2:24=A0pm, "Paul B. Andersen"
>
> > wrote:
> > > Juan R. Gonz=E1lez-=C1lvarez skrev:
>
> > > > Tom Roberts wrote on Mon, 25 Feb 2008 15:47:04 +0000:
>
> > > >> The best model we have for the propagation of light near a massive
>
> > > > no.
>
> > > >> object like the sun is GR, in which the curvature of spacetime is t=
he
> > > >> important aspect in determining the path light follows. And it agre=
es
> > > >> with measurements to part-per-million accuracy over an enormous ran=
ge.
>
> > > > Theories without spacetime curvature also agree with that.
>
> > > Could you name one of those theories, please?
>
> > Personally I know of no such theories. However spacetime curvature is
> > not neccesary for light deflection in a gravitational field. So long
> > is there is a gravitational field present, i.e. non-vanishing
> > connection coefficients, then a particle can be deflected. A uniform g-
> > field is a perfect example. The spacetime curvature associated with a
> > uniform gravitational field is zero and yet a beam of light will be
> > deflected. Geometrically speaking the deflection is described as the
> > observer corresponding to a frame of reference for which a geodesic
> > represents a non-straight line in space, i.e. one changes from
> > Minkowski coordinates to "curvilinear" coordinates. Spacetime
> > curvature is only neccesary when geodesic deviation is expected.
>
> >Pete- Hide quoted text -
>
> > - Show quoted text -
>
> HiPete
>
> I remember Kip Thorne commenting, in his non-mathematical book on the
> history of gravitational physics, that he occasionally liked to use
> teleparallel gravity to evaluate gravitational wave phenomena.
> Teleparallelism is a GR equivalent.
>
> http://en.wikipedia.org/wiki/Teleparallelism
>
> Bruce- Hide quoted text -
>
> - Show quoted text -

Hi Bruce

Thanks. I've heard of that but have not had the time to learn about
it. Other subjects have taken a higher priority lately. Thanks for
reminding me of it. Do you know much about this subject? How is
Schitz's "Gravity from the ground up?" going? Have you finished
reading it? If so how did you like it?

Best wishes

Pete