Donald T Palmgren (lonewolf@utkux.utcc.utk.edu)
Mon, 13 Jul 1998 20:44:26 +0100
On Fri, 10 Jul 1998, Jonathan B. Marder wrote:
>
> In return I will correct something Donny wrote:-
> >Now one trait of photons (light particals) is that they pair-up into
> twins: +
> >and - based on their "spin." If you alter the "spin" of one photon,
> then
> >it's twin will change as well, in order to stay paired.
> Photons don't have spin. Only charged particles (most commonly electrons
> and protons) have spin, which determines how they interact with magnetic
> fields.
I found this as a reference to the experament I'm refering to:
"Spooky corelations between
seperate photons were demonstrated in an experiment at the Royal Signals
and Raddar Establishment in England. In this simplified depiction, a
down-converter sends pairs of photons in opposite directions. Each
photon passes through a seperate two-slit apparatus and is directed by
mirrors to a detector. Because the detector cannot distinguish which
slit the photon passes through, each photon goes both ways, generating
an interference pattern in the coincidence counter. Yet each photons
direction, or momentum, is also correlated with its partners. A
measurement showing a photon going through the upper left slit would
instantaneously force its distant partner to go through the lower slit
on the right."(ScientificAmerican992p.100)
It's the mention of the "down-converter" that's puzzling, because,
in physics, "up" and "down" are used to denote spin -- A partical may have
an up spin = 1/2 and a down spin = -1/2, for example. But anyway, I'm not
a physicist and don't claim to relly understand the details here. Mainly
it's that "instantaineously" that's important here. Either, as I said, the
photons are communicating w/ each other faster than light or the universe
is some kind of unified whole, so that photons in seperate places are
still, somehow, connected.
Since this isn't QM discussion (and most of us, including me,
wouldn't be qualified for such a thing) I'm willing to leave it at thet,
but if you're still interested in hearing all the goory details,
Johnathan, a friend of mine -- who does happen to be a profesional
physicist in Switzerland -- is looking into this experiment in more
detail, and you can e-mail me directly and I can forward you more info or
sources or something. This just isn't my area of expertiese.
TTFN
Donny
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