Re: [Phys-L] foundations of physics: Galilean relativity

[Jeffrey Schnick <JSchnick@Anselm.Edu>]

Thanks for the clarification, Moses.  I clearly did not understand you correctly.  Furthermore, you were right and I was wrong.  My intuition told me that the kick a little planet would give a photon would be so small that even after a couple of years the deflection would be a fraction of a meter.  Just a little reflection shows that to be wrong and the calculation shows that for a planet with the properties of Mercury, the photon drops about .8 planet diameters in 2 years.  Thanks for making me think about it.

> -----Original Message-----
> From: Phys-l [mailto:phys-l-bounces@www.phys-l.org] On Behalf Of Moses
> Fayngold
> Sent: Wednesday, October 07, 2015 10:15 AM
> To: Phys-L@Phys-L.org
> Subject: Re: [Phys-L] foundations of physics: Galilean relativity
>
>
>
>
>      On Monday, October 5, 2015 1:46 PM, Jeffrey Schnick
> <JSchnick@Anselm.Edu> wrote:
>
> > ...If I understand them correctly, John and Moses both think that the
> acceleration of the photon is the same as that >which a particle at the original
> position of the photon would experience meaning that as the photon gets
> farther >and farther from the planet, the photon's acceleration remains
> constant at its original value in its original direction.  >That makes no sense to
> me.
>
>   To me, too. I've never said that  "...as the photon gets farther and farther
> from the planet, the photon's acceleration remains constant at its original
> value in its original direction". Nor did I mean it. We all must be very careful
> about numerous conditions and assumptions (especially unspoken ones!)
> accompanying our argument. I do think that acceleration of the photon in the
> gravity field is the same as that of any other particle at the same time and
> location. Therefore I think that acceleration of the photon pair right after the
> e-p annihilation is exactly the same as that of the initial pair, provided that
> the separation between its members had been negligible.  Only under the
> latter condition can we equate individual accelerations to that of the CM. This
> is what I meant (but had not explicitly formulated) in my previous argument.
> This statement about the discussed event at specified location in spacetime
> remains true and is experimentally manifest as deviations of the born
> photons' trajectories from their initially horizontal and strictly opposite
> directions. My second point was that already this initial deviation creates the
> corresponding transverse components of velocity (turns the photons'
> directions through a small angle), and as a result, their CM in 2Y will definitely
> be sufficiently far displaced from its initial position, even without any
> subsequent acceleration (which will indeed be increasingly
> negligent).     Unfortunately, I cannot say exactly how far does it make
> "sufficiently far". It critically depends on numerous conditions, including the
> size of the planet. But on conceptual level, I think the following example
> must be true: Suppose it would take 1s for the initial e-p pair to fall onto the
> surface of the planet if there were no annihilation. Annihilation with
> horizontal momenta of the produced photons would save the system from
> hitting the surface (or from crossing the Schwarzschild sphere in case of a
> black hole). But I think that 2Y after the event the CM of the photon pair
> must be far on the opposite side of the planet, even though the pair's CM
> would surely have no noticeable acceleration. But it would still have the initial
> transverse velocity acquired during the first 1s of the process.   Moses
> Fayngold,NJIT       _____________________________________________
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