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Comments by Sarfatti

From: paul@mtnmath.UUCP (Paul Budnik)
Subject: The collapse postulate collapses
Date: 15 Nov 92 00:31:22 GMT

"The standard approach to this problem treats the polarizer
angle and the photon detection as a single measurement of the state of the
photon. The state is detected at one site and the wave function is
collapsed in accord with that observation. This restricts the wave
function at the other site in a way that influences the probability
of a joint detection. This works only if the polarizers are not changing.
If the polarizers are not changing the experiment does not violate
locality."

Sarfatti's critique of Budnik's "The collpase postulate collapses."

Cute title - but the idea is wrong.

Budnik's remarks in quotes. writes:

#1. "If the polarizers are not changing the experiment does not violate
locality."

This is false. The standard quantum result cos^2(theta)/2 for joint
probability to measure both photons in their local "V" polarizations, for
example, violates Bell's inequality even when theta is "not changing".

#2. "In an experiment with changing polarizers, the critical element is the
delay between when the angle changes and when this affects the probability
of joint detections."

I think this is operationally meaningless. How would you measure the
"delay"?  Given two photons in the same pair created at event S - theta is
simply the orientation of one polarizer, when say photon a locally
interacts with it, minus the orientation of the other polarizer when the
twin photon b locally interacts with it. Thus, theta is a nonlocal
parameter defined jointly by two detection events A and B.  The spacetime
interval between A and B is irrelevant because information flows from A
back to S then forward to B - or the other way around (i.e. symmetry).
This was shown by Costa-de Beauregard and also recently again by a fellow
from the Technion in Fdn of Physics Letters.

Budnik then writes:

#3. "The distance between the polarizer and the detector is a critical
parameter."

On the contrary, it makes no difference whatsoever!

#4 "The delay must be as long as the time it takes light to travel from the
polarizer to the detector *at each local site*."

Given, for example, unequal distances L(a), L(b) of source from each
counter - one must compare A measurement at flight time L(a)/c with B
measurement L(b)/c - in global rest frame - all equipment relatively at
rest.  So the only significant "delay" is L(a)/c - L(b)/c.  To do anything
else is incorrect.

One could use special relativity if parts of experiment move relative to
each other near light speed etc. - but at this stage it is complicating the
issue needlessly.

#5 "If this were not true one could use this effect for superluminal
communication."

But there is "superluminal communication" , though not by the reason you
give which, I suspect, is operationally as meaningful as the pre-
Einsteinian "aether".

#5 "All you need to is locate the polarizers close to the
photon source and redirect the photons so that instead of moving apart
they travel to detectors that are closely spaced. You can then vary the
relative angle of the two polarizers and this will superluminally change
the probability of a joint detection."

I don't understand this?

I will not comment on the rest as I think it will be redundant.  The main
point is Mr. Budnik - can you spell out very simply, step by step how one
would try to measure a superluminal change in a nonlocal joint probability.
I do not know what you mean?

I think your poroblem is not a real problem once one undewrstands the key
idea which is, again, I repeat: Given two photons in the same pair created
at event S - theta is simply the orientation of one polarizer, when say
photon a locally interacts with it, minus the orientation of the other
polarizer when the twin photon b locally interacts with it. Thus, theta is
a nonlocal parameter defined jointly by two detection events A and B.  The
spacetime interval between A and B is irrelevant because information flows
from A back to S then forward to B - or the other way around (i.e.
symmetry).

paul@mtnmath.UUCP (Paul Budnik)