Re: the energy

[Jack Uretsky <jlu@HEP.ANL.GOV>]

        But, Leigh, you are accepting an uphysical starting point:

On Fri, 29 Oct 2004, Leigh Palmer wrote:

> Sorry, folks. I'm still catching up.
>
> On 21-Oct-04, Michael Edmiston wrote:
>
> > Prior to Rick Tarara's response (below) I was about ready to ask if
> > we've been watching too many movies like "The Matrix."  I guess I'll
> > ask
> > that anyway.  And I also second John D's closing remark, that it
> > pointless to get too hung up on this.
> >
> > I would like to make a few more comments about the idea of
> > inter-conversion and the idea of flow.  I understand the points Jim and
> > Leigh have made.  I don't argue, yet I do argue.  The problem is what
> > choice of words do we want to use to describe some of the things we see
> > (or think we see).
> >
> > A photon is traveling in some region, and all of a sudden...  poof...
> > the photon is gone and in its place we see a positron and an electron.
> > We discover this is energy related because not any photon can do this.
> > The photon must have an energy of  at least 1.022 MeV which is the
> > E=mc^2 equivalent of the rest mass of the positron and the electron.

1.  Photons cannot be localized to "regions".
2.  The photon was not observable.  It is correct to say that at some time
(depending upon the detector) a vertex occurred that could be interpreted
as e+ e- production.  We can measure the momenta of the members of the
pair and, using energy-momentum conservation, deduce the energy of the
photon that produced them.  Here I have already substantially simplified
the detection process, but Michael's paragraph does not correspond to
physics.
                                        Regards,
                                                Jack

--
"Trust me.  I have a lot of experience at this."
                General Custer's unremembered message to his men,
                just before leading them into the Little Big Horn Valley