physicists ask photons where they've been
"Lee Corbin" <[email protected]> Sat, 30 Nov 2013 07:23:37 -0800
| Newsgroups | gmane.science.physics.fabric-of-reality |
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Hi everyone,
and especial hello to any old friends who remember me from 7-8 years back or
so.
Wanting to get back in the swing of things, find out what's the buzz (tell
me what's happening), and also pose some questions, let me start by asking
if anyone's read about the evidently new experiment described in
http://physicsworld.com/cws/article/news/2013/nov/26/physicists-ask-photons-where-have-you-been
Ultimately, I would like to understand the experiment better (I'll say below
what I already know), and see if the result can be straightforwardly
explained in the MWI view.
Thanks very much,
Lee Corbin
P.S. What I've understood and perhaps added to about the above experiment:
I’ve made some progress trying to understand this experiment,
but require more, though, to understand it in anything like a
satisfactory sense (e.g. using MWI).
If you care to read it, two important points about the experiment are
insufficiently stressed in the article. One is that the “external”
mirrors
that accomplish the external interference are set up as carefully as
possible to *create* interference. That is, the path lengths of the
photons—insofar as they are affected by the two mirrors E and F—are
designed to promote complete interference. So if left just to them,
e.g.
augmented by a completely stable single mirror at B, then perfect
interference would be attained.
Such perfect interference would mean that half the time the photons
would take the left/bottom route (through mirror C) and the other half
the time they would take the path through E, B, and F. The whole point
of the interior interference is to complicate the aforesaid, long known
perfect or near-perfect interference.
The other point that is not sufficiently stressed is that the internal
mirrors A and B are set as nearly as possible to *destroy*
interference.
Consider the extremely small instant in time when all the mirrors are
in their exact intermediate positions (midway between extreme positions
as they vibrate). In this case, no interference at all is possible, and
the half of photons that take the extreme left and bottom path through
C are themselves split into two groups, those that make it out of the
apparatus to the recorder at D and those that leave through the very
bottom path downward. Likewise in this case, the other half that don’t
go through C can never interfere with those taking the path just
described, and so themselves are also split into two groups, those
exiting on the right and those exiting at the bottom.
In this last case—where the mirrors are at the exact midpoints of their
vibrations—all photons are accounted for, and a total of half exit the
apparatus at the bottom right and half go down and out the bottom.
I may have some more to say (conjectures) but better leave it like
this for now. The above just clarifies what’s in the article.
(Corrections & criticism craved, as is the Popperian standard.)
<eom>
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<p>Hi everyone,<br>
<br>
and especial hello to any old friends who remember me from 7-8 years back o=
r <br>
so.<br>
<br>
Wanting to get back in the swing of things, find out what's the buzz (t=
ell <br>
me what's happening), and also pose some questions, let me start by ask=
ing <br>
if anyone's read about the evidently new experiment described in<br>
<br>
http://physicsworld.com/cws/article/news/2013/nov/26/physicists-ask-photons=
-where-have-you-been<br>
<br>
Ultimately, I would like to understand the experiment better (I'll say =
below <br>
what I already know), and see if the result can be straightforwardly <br>
explained in the MWI view.<br>
<br>
Thanks very much,<br>
Lee Corbin<br>
<br>
P.S. What I've understood and perhaps added to about the above experime=
nt:<br>
<br>
I=E2=80=99ve made some progress trying to understand this experiment,<br>
but require more, though, to understand it in anything like a<br>
satisfactory sense (e.g. using MWI).<br>
<br>
If you care to read it, two important points about the experiment are<br>
insufficiently stressed in the article. One is that the =E2=80=9Cextern=
al=E2=80=9D <br>
mirrors<br>
that accomplish the external interference are set up as carefully as<br=
>
possible to *create* interference. That is, the path lengths of the<br=
>
photons=E2=80=94insofar as they are affected by the two mirrors E and F=
=E2=80=94are<br>
designed to promote complete interference. So if left just to them, <b=
r>
e.g.<br>
augmented by a completely stable single mirror at B, then perfect<br>
interference would be attained.<br>
<br>
Such perfect interference would mean that half the time the photons<br>
would take the left/bottom route (through mirror C) and the other half<=
br>
the time they would take the path through E, B, and F. The whole point=
<br>
of the interior interference is to complicate the aforesaid, long known=
<br>
perfect or near-perfect interference.<br>
<br>
The other point that is not sufficiently stressed is that the internal<br>
mirrors A and B are set as nearly as possible to *destroy*<br>
interference.<br>
<br>
Consider the extremely small instant in time when all the mirrors are<br>
in their exact intermediate positions (midway between extreme positions=
<br>
as they vibrate). In this case, no interference at all is possible, and=
<br>
the half of photons that take the extreme left and bottom path through<=
br>
C are themselves split into two groups, those that make it out of the<b=
r>
apparatus to the recorder at D and those that leave through the very<br=
>
bottom path downward. Likewise in this case, the other half that don=E2=
=80=99t<br>
go through C can never interfere with those taking the path just<br>
described, and so themselves are also split into two groups, those<br>
exiting on the right and those exiting at the bottom.<br>
<br>
In this last case=E2=80=94where the mirrors are at the exact midpoints of t=
heir<br>
vibrations=E2=80=94all photons are accounted for, and a total of half e=
xit the<br>
apparatus at the bottom right and half go down and out the bottom.<br>
<br>
I may have some more to say (conjectures) but better leave it like<br>
this for now. The above just clarifies what=E2=80=99s in the article.<b=
r>
(Corrections & criticism craved, as is the Popperian standard.)<br>
<eom><br>
<br>
</p>
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