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Re: [ontolog-forum] Model or Reality

To: ontolog-forum@xxxxxxxxxxxxxxxx
From: Randall R Schulz <rschulz@xxxxxxxxx>
Date: Sun, 12 Aug 2007 13:34:16 -0700
Message-id: <200708121334.16822.rschulz@xxxxxxxxx>
On Sunday 12 August 2007 12:48, Pat Hayes wrote:
> > ...
> >
> >Anyway, there are some so-called "interpretations" of quantum theory
> >that suggest a limited form of backward-in-time influence. I'm
> > thinking of John Cramer's "Transactional Interpretation of Quantum
> > Mechanics"
> +1 ! My absolute favorite explanation of QM. Way
> more convincing (and intuitive) than the
> Copenhagen interpretation, with all its
> mysterious overlapping states and half-dead cats
> and collapsing wave functions and so on. See
> http://www.npl.washington.edu/npl/int_rep/tiqm/TI_toc.html
> for a pretty readable account.    (01)

If only they were half-dead. But completely dead and fully alive at the 
same time?    (02)

> ...
> >
> >Personally, I find it delightfully mind-boggling. ...
> But the delicious thing is the observation that
> (following special relativity), these are in fact
> contemporary over long enough distances. Put
> another way: from the photon's point of view, it
> takes no time at all to go any distance. So going
> backwards or forwards in time at the speed of
> light isn't really much of a big deal. At the
> speed of light, there is no time in the ordinary
> sense.    (03)

I like to think of it, metaphorically, of course, as the 
photon "kissing" both the emitter and absorber simultaneously. Cute, 
eh?    (04)

One simple, everyday way to think about this is that photons are 
not "cast off" by emitters, they are _exchanged_ by mutual "agreement" 
of the emitter and absorber.    (05)

It suggests an interesting gedanken experiments. For example, what would 
happen if a single hydrogen atom in a non-ground state were situated at 
the center of a perfectly reflecting sphere? Would it ever emit a 
photon? The only destination for that photon would be the same atom. If 
photon were cast off, then a photon would be emitted, reflected by the 
inside of the spherical surface and impinge again on the atom that 
emitted it. It would either be absorbed or continue to be reflected 
inside the sphere until it eventually were absorbed, leaving the 
hydrogen atom again in an excited state.    (06)

On the other hand, the transactional interpretation would suggest that 
the excited hydrogen atom would remain in its excited state, since it 
cannot participate in the transaction that allows it to absorb the 
photon it would emit.    (07)

Unfortunately, for a number of reasons, I cannot think of a way to carry 
out such an experiment.    (08)

The next thing to do is dispense with all this "many worlds" nonsense 
that some justify based on the single-photon, multiple-slit 
experiments. It boggles my mind (in an entirely unpleasing way) that 
the proponents of this notion completely overlook the fact that photons 
are bosons and don't interfere with each other, let alone themselves, 
in this manner. When you apply the transactional interpretation to the 
observation that in a two-slit experiment where only a single photon 
ever traverses the apparatus at a time and yet an interference pattern 
emerges in the distribution of the photon absorption locations, you 
immediately see that it's the wave function of the emitter that 
produces the interference pattern (since it is defined throughout the 
light cone of the emission event), not the photons traversing the 
path(s) between the emitter and the absorber (detector).    (09)

Another way to think about this is that photons cannot "cancel" each 
other out, since their energy must be absorbed (or they keep 
propagating). How could two (or two ... what? copies? ... of the same 
photon) interfere with each other and have their energy disappear? Of 
all the "laws" of physics that have had to be reconsidered, the 
conservation laws stand strong.    (010)

> Which is one reason I love the Cramer picture.    (011)

I love it because I still think it offers a way to signal backward in 
time. I've even devised an experiment, which I think could be carried 
out in any decent laser optics lab, that would illustrate (or not) the 
phenomenon I have in mind.    (012)

> Pat    (013)

Randall Schulz    (014)

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