| Topic: |
Science > Physics |
| User: |
"Fred" |
| Date: |
07 Apr 2006 08:38:34 AM |
| Object: |
Collapse of Bohmian Wave Function |
I'm studying this:
http://plato.stanford.edu/entries/qm-bohm/
Some questions.
In convensional quantum mechanics. Putting a detector in one of
the slits can collapse the wave function. In Bohmian Mechanics.
They explained that there is no collapse. It's just that the double
slit is no longer isolated system by the introduction of the detector
which alters the wave characteristic. But does this really makes
sense. How come the wave characteristic is so altered as to cause
the entire disappearance of the interference by simply
introducing the detector. Convensional quantum mechanics
explained it that the which way path is known and the wave
function collapsed. But in Bohmians. How can extending the
system (by the introduction of the detector) results in such
drastic changes? Note Bohmians don't even believe in
decoherence because their wave function never collapse.
It's just being overrided by the larger value of the measuring
device. But what if the measuring device is a mere detector
in one of the slits. How can it affect the guiding equation
so drastically as to cancel the entire interference (Bohmian
wise)?
Also if you have encountered a Bohmian version of Quantum
field theory, let me know. The Relativity LET has the IIja equivalent
of GLET. Has there a QFT version of Bohmians attempted by
these theoretical explorers? Also how do you make the Bohmian
guiding wave obey Lorentz Invariance. Is this an almost
impossibility? Even in convensional QM. How do you make
the nonlocality characteristic obey Lorentz Invariance?
Thanks.
Fred
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| User: "" |
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| Title: Re: Collapse of Bohmian Wave Function |
07 Apr 2006 09:57:09 AM |
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Fred wrote:
I'm studying this:
http://plato.stanford.edu/entries/qm-bohm/
Some questions.
In convensional quantum mechanics. Putting a detector in one of
the slits can collapse the wave function. In Bohmian Mechanics.
They explained that there is no collapse. It's just that the double
slit is no longer isolated system by the introduction of the detector
which alters the wave characteristic.
But that's not what happens, that's what happens
in The Aspect Experiments.
There is enough evidence from double slits now
to conclude that an interence never even forms to start with
in over 99.99999% of double slit experiments.
But does this really makes
sense. How come the wave characteristic is so altered as to cause
the entire disappearance of the interference by simply
introducing the detector. Convensional quantum mechanics
explained it that the which way path is known and the wave
function collapsed. But in Bohmians. How can extending the
system (by the introduction of the detector) results in such
drastic changes? Note Bohmians don't even believe in
decoherence because their wave function never collapse.
It's just being overrided by the larger value of the measuring
device. But what if the measuring device is a mere detector
in one of the slits. How can it affect the guiding equation
so drastically as to cancel the entire interference (Bohmian
wise)?
Also if you have encountered a Bohmian version of Quantum
field theory, let me know. The Relativity LET has the IIja equivalent
of GLET. Has there a QFT version of Bohmians attempted by
these theoretical explorers? Also how do you make the Bohmian
guiding wave obey Lorentz Invariance. Is this an almost
impossibility? Even in convensional QM. How do you make
the nonlocality characteristic obey Lorentz Invariance?
Thanks.
Fred
.
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| User: "Edward Green" |
|
| Title: Re: Collapse of Bohmian Wave Function |
07 Apr 2006 11:59:28 AM |
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Fred wrote:
I'm studying this:
http://plato.stanford.edu/entries/qm-bohm/
Some questions.
In convensional quantum mechanics. Putting a detector in one of
the slits can collapse the wave function. In Bohmian Mechanics.
They explained that there is no collapse. It's just that the double
slit is no longer isolated system by the introduction of the detector
which alters the wave characteristic. But does this really makes
sense. How come the wave characteristic is so altered as to cause
the entire disappearance of the interference by simply
introducing the detector.
Well, it's not, in general. You put a detector in which is only
partially efficient, which doesn't completely block the slit, you need
not completely destroy the interference pattern.
Convensional quantum mechanics
explained it that the which way path is known and the wave
function collapsed.
"Conventional quantum mechanics" doesn't attempt to explain much. It
does note that for a large and apparently exhaustive class of
experiments that a wave function or functional equivalent thereof
formulated according to a rule set predicts the probabilities of
various experimental outcomes. It also notes that, in applying this
rule set, the further predictive power of the original wavefunction is
usually extinguished by the outcome of said experiments, also known as
"observations", requiring us to start a fresh wave function to predict
further observational probabilities.
But in Bohmians. How can extending the
system (by the introduction of the detector) results in such
drastic changes? Note Bohmians don't even believe in
decoherence because their wave function never collapse.
It's just being overrided by the larger value of the measuring
device. But what if the measuring device is a mere detector
in one of the slits. How can it affect the guiding equation
so drastically as to cancel the entire interference (Bohmian
wise)?
There is certainly some sound insight in what you attribute to
"Bohmians". I would express it by saying that there is presumably one
continguous universe and that what we label "observations" is
presumably somewhat arbitrary, so why should we expect a theory which
honors our arbitrary label by changing form drastically for the
description of these events?
For your so called conventional quantum mechanics, there really is no
problem: the bare bones "interpretation" is what I described above.
You are free to try to embed the observation that said rule set has
said predictive power into whatever larger framework you wish, so long
as it preserves the observed limiting behavior. And this is just what
I think Bohm, as well as the so-called "many-worlds" interpretation
have done. Another approach to embedding the observed success in a
larger theory is to guess that there really _is_ something special
about "observations", for which two candidate specialities are the
participation of a conscious mind, and irreversible physical changes
(in the sense of thermodynamics).
A curious person certainly will attempt to understand how the observed
(no connection with special sense of "observation") success of, what in
this context, in often refered to as the formalism of quantum mechanics
may be embedded in a larger theory. Borderline personality disorders
seen in this context are "don't think about it", and, having identified
one possible larger embedding, a rush to embrace this possibility and
defend it, to believe in it, as you put it.
Your use of sentence fragments seems distracting.
zzbunker@netscape.net wrote:
There is enough evidence from double slits now
to conclude that an interence never even forms to start with
in over 99.99999% of double slit experiments.
Suppose I shine a coherent light source through two slits. I observe
an interference pattern. I recheck my observation every second. Since
you assert so many nines, I don't have to keep this up very long to
skew your statistics!
Now what are you talking about?
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