| Topic: |
Science > Physics |
| User: |
"Robert" |
| Date: |
16 Oct 2005 04:23:53 PM |
| Object: |
Interpreting Quantum Mechanics |
I would like people who take physics seriously (no Usenet crackpots, please,
you know who you are) to comment on the following eight ways that it is
possible to interpret quantum mechanics. In both a famous article and book
("Quantum Reality" Nick Herbert discusses eight now well-know ways of
interpreting QM.
My question is this: Are there any new variants of these ideas that have
appeared in the last 20 years that physicists take seriously? Are there any
totally new ideas, i.e. interpretations of QM that don't fit into any of
these eight ideological boxes?
Are there any experiments which most physicists agree can, or at least in
principle could, show us which interpretations are more true?
Many people talk about decoherence as a solution to the question of how a
wave function collapses. Assuming that this idea is tenable (or possibly
certainly true) would this favor any of the following interpretations, be
neutral to all of them, or perhaps suggest yet a different interpretation of
QM?
I thank you in advance for your consideration and time. If you want to just
briefly mention a possibility and suggest a book to read on that topic, that
would be much appreciated as well!
Thanks,
Robert
----
Nick Herbert talks about "Quantum Reality":
Quantum Reality #1 The Copenhagen Interpretation, Part I - There is no deep
reality.... Everyday phenomena are themselves built not out of phenomena but
out of an utterly different kind of being. Far from being a crank or
minority position, "There is no deep reality" represents the prevailing
doctrine of establishment physics. Because this quantum reality was
developed at Niels Bohr's Copenhagen institute, it is called the "Copenhagen
interpretation." ...
Quantum Reality #2. The Copenhagen interpretation, Part II - Reality is
created by observation....The Copenhagen interpretation properly consists of
two distinct parts: I. There is no reality in the absence of observation; 2.
Observation creates reality . "You create your own reality," is the theme of
Fred Wolf's "Taking the Quantum Leap."
....John Wheeler's memorable maxim for separating what is real in the world
from what is not: "No elementary phenomenon is a real phenomenon until it is
an
observed phenomenon,"
Quantum Reality #3 - Reality is an undivided wholeness. The views of Walter
Heider exemplify a third unusual claim of quantum physicists: that in spite
of its obvious partitions and boundaries, the world in actuality is a
seamless and inseparable whole...
....Heitler accepts an observer-created reality but adds that the act of ob
servation also dissolves the boundary between observer and observed: "The
observer appears, as a necessary part of the whole structure, and in his
full capacity as a conscious being. The separation of the world into an
'objective outside reality' and 'us,' the self-conscious onlookers, can no
longer be maintained. Object and subject have become inseparable from each
other."
Physicist David Bohm of London's Birkbeck College has especially stressed
the necessary wholeness of the quantum world...
Quantum Reality #4 The many-worlds interpretation. Reality consists of a
steadily increasing number of parallel universes.... For any situation in
which several different outcomes are possible some physicists believe that
all outcomes actually occur. In order to accommodate different outcomes
without contradiction , entire new universes spring into being, identical in
every detail except for the single outcome that gave them birth.
....Invented in 1957 by Hugh Everett, a Princeton graduate student, the
many-worlds interpretation is a latecomer to the New Physics scene. Despite
its bizarre conclusion, that innumerable parallel universes each as real as
our own actually exist, Everett's many-worlds picture has gained
Considerable support among quantum theorists...
Quantum Reality #5: Quantum logic (The World obeys a non-human kind of
reasoning.) ...we must scrap our very mode of reasoning, in favor of a new
quantum logic.
For two thousand years, talk about logic (in the West) was cast in the
syllogistic mold devised by Aristotle. In the mid-nineteenth century, George
Boole, an Irish schoolteacher, reduced logical statements to simple
arithmetic by inventing an artificial symbolic language which laid bare the
logical bones of ordinary language.
....a few creative logicians amused themselves by constructing "crazy logics"
using rules other than Boole's, These deviant designs for AND/OR/NOT,
although mathematically consistent, were considered mere curiosities since
they seemed to fit no human pattern of discourse. However, according to some
New Physicists, one of these crazy logics may be just what we need to make
sense out of quantum events. Listen to quantum theorist David Finkelstein
calling for mutiny against the rules of Boole: "Einstein threw out the
classical concept of time; Bohr throws out the classical concept of truth .
.. . Our classical ideas of logic are simply wrong in a basic practical way.
The next step is to learn to think in the right way, to learn to think
quantum-logically."
Quantum Reality #6. Neorealism (The world is made of ordinary objects.) An
ordinary object is an entity which possesses attributes of its own whether
observed or not... The clarity and ubiquity of ordinary reality has seduced
a few physicists - I call them neorealists - into imagining that this
familiar kind of reality can be extended into the atomic realm and beyond.
Neorealists...accuse the orthodox majority of wallowing in empty formalism
and obscuring the world's simplicity with needless mystification. Instead
they preach return to a pure and more primitive faith. Chief among
neorealist rebels was Einstein, whose passion for realism pitted him
squarely against the quantum Orthodoxy...
Quantum Reality #7 Consciousness creates reality... a small faction asserts
that only an apparatus endowed with consciousness (even as you and I) is
privileged to create reality. The one observer that counts is a conscious
observer.
....Eugene Wigner...comments on this ironic turn of events: "It is not
possible to formulate the laws of quantum mechanics in a fully consistent
way with out reference to the consciousness . . . It will remain remarkable
in whatever way our future concepts may develop, that the very study of the
external world led to the conclusion that the content of the consciousness
is an ultimate reality."
Quantum Reality #8. The duplex world of Werner Heisenberg (The world is
twofold, consisting of potentials and actualities.) Most physicists believe
in the Copenhagen interpretation, which states that there is no deep
reality- QR # 1) and observation creates reality QR # 2). What these two
realities have in common is the assertion that only phenomena are real; the
world beneath phenomena is not.
One question which this position immediately brings to mind is this: "if
observation creates reality, what does it create this reality out of? Are
phenomena created out of sheet nothingness or out of some more substantial
stuff?" Since the nature of unmeasured reality is unobservable by
definition, many physicists dismiss such questions as meaningless on
pragmatic grounds.
According to Heisenberg, there is no deep reality - nothing down there
that's real in the same sense as the phenomenal facts are real.... "But the
atoms and the elementary particles themselves are not as real; they form a
world of potentialities or possibilities rather than one of things or facts
.. . .
....Heisenberg's two worlds are bridged by a special interaction which
physicists call a "measurement." During the magic measurement act, one
quantum possibility is singled out, abandons its shadowy sisters, and
surfaces in our ordinary world as an actual event. Everything that happens
in our World arises out of possibilities prepared for in that other-the
world of quantum potentia. In turn, our world sets limits on how far crowds
of Potentia can roam. Because certain facts are actual, not everything is
possible in the quantum world. There is no deep reality, no deep
reality-as-we-know-it....
[...cutting towards the end of Nick Herbert's article...]
Since these quantum realities differ SO radically, one might expect them to
have radically different experimental consequences. An astonishing feature
of these eight quantum realities, however, is that they are experimentally
indistinguishable. For all presently conceivable experiments, each of these
realities predicts exactly the same observable phenomena.
....Likewise modern physicists do not know how to determine experimentally
what kind of world they actually live in. However, since "reality has
consequences" we might hope that future experiments, not bound by our
current concepts of measurability, will conclusively establish one or more
of these bizarre pictures as top-dog reality. At present, however, each of
these quantum realities must be regarded as a viable candidate for "the way
the world really is." They may, however, all be wrong.
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| User: "The Unstable Concoction of Fascinet" |
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| Title: Re: Interpreting Quantum Mechanics |
17 Oct 2005 02:03:52 PM |
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A question that I've currently been interested in (and have no answer
for), and I don't know the extent to which it's been investigated (as
it were), is the interpretations of quantum mechanics and second
quantization.
I recall when I was an undergraduate, all the professors were calling
QM a math class, and I've seen no reason to change my opinion of junior
level QM classes since then. Even if it's not strictly mathematics,
quite a lot is. Other branches of mathematics are applicable to
different phenomena and they have different interpretation when they
do. The closest to this case (mathematically) would be probability
theory, which has different interpretations in data analysis and
information theory.
Is there any reason to think, then, that photons and magnons, although
both quantum mechanical, should hold the same interpretation in the
sense of the eight interpretations given above?
-F
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| User: "Tice with a J" |
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| Title: Re: Interpreting Quantum Mechanics |
16 Oct 2005 11:36:36 PM |
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Found one! Behold:
<a
href="http://mist.npl.washington.edu/npl/int_rep/tiqm/TI_toc.html">The
Transactional Interpretation!</a>
See also <a href="http://www.mtnmath.com/faq/meas-qm-8.html">here</a>.
No one's called Cramer a crank, so it's probably a legitimate
interpretation.
As for these theories making physical predictions, ponder this:
Einstein and others postulated that there was some sort of "hidden
variable" governing the behavior of particles that regular quantum
mechanics discover. This is the "realist" position: the particle is
somewhere, we just can't see it. However, a little thought experiment
showed that this could not be the case. Their interpretation had
physical consequences, and the consequences never showed up. I believe
that eventually we'll find a way to determine which of these myriad
interpretations is correct.
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| User: "Harry" |
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| Title: Re: Interpreting Quantum Mechanics |
17 Oct 2005 09:26:37 AM |
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"Tice with a J" <lodo.bear@gmail.com> wrote in message
news:1129523796.174978.248390@g44g2000cwa.googlegroups.com...
Found one! Behold:
<a
href="http://mist.npl.washington.edu/npl/int_rep/tiqm/TI_toc.html">The
Transactional Interpretation!</a>
See also <a href="http://www.mtnmath.com/faq/meas-qm-8.html">here</a>.
No one's called Cramer a crank, so it's probably a legitimate
interpretation.
As for these theories making physical predictions, ponder this:
Einstein and others postulated that there was some sort of "hidden
variable" governing the behavior of particles that regular quantum
mechanics discover. This is the "realist" position: the particle is
somewhere, we just can't see it. However, a little thought experiment
showed that this could not be the case. Their interpretation had
physical consequences, and the consequences never showed up. I believe
that eventually we'll find a way to determine which of these myriad
interpretations is correct.
What "little thought experiment"? If you mean Bell's, it's much less
clear-cut then you suggest, and meant to be done in reality. According to
Gisin, to date no single experiment has been done that is free of known
loopholes.
Harald
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| User: "Greysky" |
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| Title: Re: Interpreting Quantum Mechanics |
17 Oct 2005 02:41:33 AM |
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"Tice with a J" <lodo.bear@gmail.com> wrote in message
news:1129523796.174978.248390@g44g2000cwa.googlegroups.com...
Found one! Behold:
<a
href="http://mist.npl.washington.edu/npl/int_rep/tiqm/TI_toc.html">The
Transactional Interpretation!</a>
See also <a href="http://www.mtnmath.com/faq/meas-qm-8.html">here</a>.
No one's called Cramer a crank, so it's probably a legitimate
interpretation.
As for these theories making physical predictions, ponder this:
Einstein and others postulated that there was some sort of "hidden
variable" governing the behavior of particles that regular quantum
mechanics discover. This is the "realist" position: the particle is
somewhere, we just can't see it. However, a little thought experiment
showed that this could not be the case. Their interpretation had
physical consequences, and the consequences never showed up. I believe
that eventually we'll find a way to determine which of these myriad
interpretations is correct.
There are many interpretations of quantum mechanics - mostly it depends on
the individuals comfort level. Hidden variables can cause many an argument
and has down through the years. If you don't like dealing with hidden
variables, you may want to check out Robert B Griffiths Consistent
interpretation to QM. It is a bit limited in its approach to real world
problems but in Griffiths simplified view the non local phenomena implied by
the n-slit experiment can be made to 'go away'. You may want to check out
Griffiths book 'Consistent Quantum Theory' - ISBN 0-521-53929-3, by
Cambridge University Press. Now, I happen not to agree with his view. I
consider it too restrictive, but it is a nice read.
Greysky
www.allocations.cc
Learn how to build a FTL radio.
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| User: "Tice with a J" |
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| Title: Re: Interpreting Quantum Mechanics |
16 Oct 2005 11:38:14 PM |
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Darn. I thought hyperlinks worked here. My apologies for the clutter.
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| User: "John Bailey" |
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| Title: Re: Interpreting Quantum Mechanics |
18 Oct 2005 04:37:54 PM |
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On Sun, 16 Oct 2005 21:23:53 GMT, "Robert" <rkscience100@yahoo.com>
wrote:
I would like people who take physics seriously (no Usenet crackpots, please,
you know who you are) to comment on the following eight ways that it is
possible to interpret quantum mechanics. In both a famous article and book
("Quantum Reality" Nick Herbert discusses eight now well-know ways of
interpreting QM.
My question is this: Are there any new variants of these ideas that have
appeared in the last 20 years that physicists take seriously? Are there any
totally new ideas, i.e. interpretations of QM that don't fit into any of
these eight ideological boxes?
...Likewise modern physicists do not know how to determine experimentally
what kind of world they actually live in. However, since "reality has
consequences" we might hope that future experiments, not bound by our
current concepts of measurability, will conclusively establish one or more
of these bizarre pictures as top-dog reality. At present, however, each of
these quantum realities must be regarded as a viable candidate for "the way
the world really is." They may, however, all be wrong.
I went looking for a match between Nick Herberts classification, and
those of my collection of reprints. After seeing how hopeless that
was ((after the first four) Herbert must have a different paradigm for
interpretations than those of the authors I collect) I strongly
recommend this light hearted plea by Chris Fuchs. It not only presents
a perspective in support of Quantum Information interpretation, it
provides critical factors to be examined in other interpretations.
Quantum Foundations in the Light of Quantum Information
Author: Christopher A. Fuchs, Bell Labs
http://xyz.lanl.gov/abs/quant-ph/0106166
(quoting the abstract--from the paper not lanl]s abstract)
In this paper, I try to cause some good-natured trouble. The issue at
stake is when will we ever stop burdening the taxpayer with
conferences and workshops devoted explicitly or implicitly to the
quantum foundations? The suspicion is expressed that no end will be in
sight until a means is found to reduce quantum theory to two or
three statements of crisp physical (rather than abstract, axiomatic)
signi cance. In this regard, no tool appears to be better calibrated
for a direct assault than quantum information theory.
Far from being a strained application of the latest fad to a
deepseated problem, this method holds promise precisely because a
large part (but not all) of the structure of quantum theory has always
concerned information. It is just that the physics community has
somehow forgotten this.
One is left with the feeling an almost salty feeling that perhaps this
is the whole point to quantum mechanics. That is: Perhaps the missing
ingredient for narrowing the structure of Bayesian probability down to
the structure of quantum mechanics has been in front of us all along.
It finds no better expression than in the taking account of the
limitations the physical world poses to our ability to come to
agreement.
Now quoting myself:
The uncertaintly principle is just short hand for one aspect of the
weird behavior of matter at very small dimensions. It's more a rule
of thumb than a physical principle. The truth is that the behavior of
particles for which the uncertainty principle applies are so different
from billiard balls that adding the band-aid of the uncertaintly
principle only gives a rough idea about what they do.
Quantum physics seems weird to us because most of our experience is
with objects which are large enough to convey information in excess of
the questions we are likely to ask them. If objects are extremely
small and have only a few qubits of information, when we ask the
object for information by performing an experiment, it gives ambiguous
answers because the information needed to answer unambiguously is
inherently lacking. This seems weird to us because we lack experience
with such information limited objects.
The way objects that are extremely small and hence limited in their
information response construct their ambiguous answers is quantified
by the theory of quantum mechanics which prescribes the probability
distribution of the values of the answers the objects yield when
tested for the answers they inherently cannot completely give.
Interpretation of quantum physics as the behavior of information
limited objects is relatively new. Many papers on the subject can be
found under the general subject of Information Physics. To my
knowledge, none attempt to explain their conclusions in terms suitable
for the non-specialist. The above remarks represent my own spin (no
pun intended) on the subject. I would welcome other efforts to express
these ideas in useful, non-specialist language.
The following are intended as references which may be used to defend
the underlying physics as explained above from carping, nit-picking
and general flame mongering.
references:
http://xyz.lanl.gov/abs/quant-ph/0006033
The information interpretation of quantum mechanics by Svozil
http://xyz.lanl.gov/abs/quant-ph/0106125
Covariance and Fisher information in Quantum Mechanics by Petz
http://www.arc.unm.edu/Conferences/Roy_Frieden_Abstract.html
Information Measures - Does it pay to be ignorant? B. Roy Frieden
http://www.santafe.edu/~shalizi/reviews/physics-from-fisher-info/
Physics from Fisher Information A Unification by B. Roy Frieden
http://xyz.lanl.gov/abs/gr-qc/0109068
Entropic Dynamics by Caticha
http://xyz.lanl.gov/abs/quant-ph/0106133
Quantum probabilities as Bayesian probabilities by Caves, Fuchs, and
Schack
http://xyz.lanl.gov/abs/quant-ph/0011036
Quantum Information Theory by Nielson
http://xyz.lanl.gov/abs/quant-ph/0005021
Entanglement, thermalisation and stationarity: The computational
foundations of quantum mechanics by Guruprasad
http://www.cs.umain.edu/~chaitin/cmu.html
John Bailey
http://home.rochester.rr.com/jbxroads/mailto.html
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| User: "Ben Rudiak-Gould" |
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| Title: Re: Interpreting Quantum Mechanics |
19 Oct 2005 07:17:35 PM |
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John Bailey wrote:
Quantum Foundations in the Light of Quantum Information
Author: Christopher A. Fuchs, Bell Labs
http://xyz.lanl.gov/abs/quant-ph/0106166
Um.
There's some decent material in this paper, but I'd be embarrassed to
recommend it to anyone given how childish and ignorant it is in its
discussion of other interpretations.
Once the author has gotten the name-calling out of his system
("Everettistas"?), and has compared himself (albeit obliquely) to Einstein,
and has all but called his opponents "hidebound reactionaries" and
"self-appointed defenders of the orthodoxy", he finally gets around to
presenting his contribution, which turns out to be a pretty good defense of
the Bayesian interpretation of the wave function, i.e. the idea that the
wave function represents some agent's state of knowledge and not any
property of the system under study. He points out, for example, the
similarity of the "collapse" rule to a Bayesian update. The problem is that
he seems to think that this is a new idea, and that it will be unfamiliar to
his readers. It's actually the oldest idea around; it's the position that
Bohr took, and I would call it the "Copenhagen interpretation", except that
I think that term should be retired because it's used for too many different
things.
One thing crackpots tend to do a lot is say "the experts are fools for
failing to recognize X", where either X is not true, or the experts explored
it and moved to other things long ago. Another thing crackpots tend to do is
project their religious belief in their own theory onto others, and you'll
find that here too. I have my own biases, but I do understand the Bayesian
interpretation and think it's interesting; I also understand various other
interpretations and think that they're interesting in their own way. I don't
think Fuchs understands any other view of quantum mechanics than the one he
presents here. His criticisms of the other interpretations amount only to
saying that they don't make sense from the perspective of the Bayesian
interpretation, which is not especially insightful.
Overall this is a terrible paper, but if the opening rant were deleted and
the abstract rewritten, it could be a pretty good paper.
-- Ben
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| User: "John Bailey" |
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| Title: Re: Interpreting Quantum Mechanics |
20 Oct 2005 09:43:28 AM |
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On Thu, 20 Oct 2005 01:17:35 +0100, Ben Rudiak-Gould
<br276deleteme@cam.ac.uk> wrote:
John Bailey wrote:
Quantum Foundations in the Light of Quantum Information
Author: Christopher A. Fuchs, Bell Labs
http://xyz.lanl.gov/abs/quant-ph/0106166
Um.
There's some decent material in this paper, but I'd be embarrassed to
recommend it to anyone given how childish and ignorant it is in its
discussion of other interpretations.
Everything is relative.
You said in your earlier post you hadn't read Nick Herbert's book.
Compared to Herbert, Fuchs is a paragon. Possibly, his paper should
be read in the context it was probably given--aimed at cynical, jaded
professionals, deliberately provocative and intended to evoke some
humor.
Your critique was quite helpful in my own search for a useful
interpretation.
How do you feel about:
Copenhagen Computation: How I Learned to Stop Worrying and Love Bohr
by David Mermin http://xyz.lanl.gov/abs/quant-ph/0305088?
(Others should be warned, the humor is almost exclusively in the
title.)
Or for that matter, what's your critique of Deutsch?
John Bailey
http://home.rochester.rr.com/jbxroads/mailto.html
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| User: "Ben Rudiak-Gould" |
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| Title: Re: Interpreting Quantum Mechanics |
17 Oct 2005 04:01:19 PM |
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Robert wrote:
I would like people who take physics seriously (no Usenet crackpots, please,
you know who you are) to comment on the following eight ways that it is
possible to interpret quantum mechanics. In both a famous article and book
("Quantum Reality" Nick Herbert discusses eight now well-know ways of
interpreting QM.
I haven't read this book, but I warn you that it's probably highly
inaccurate. Accurate and informative physics books rarely become popular.
The popular books are the ones that read like science fiction, and for the
most part are.
Are there any
totally new ideas, i.e. interpretations of QM that don't fit into any of
these eight ideological boxes?
If Herbert actually implies that these "eight ideological boxes" represent
an accurate classification of QM interpretations, then that's a good example
of the inaccuracy I predicted above. It's not a sensible classification at all.
I would divide interpretations into three somewhat fuzzy categories. In the
first category are mathematically rigorous reformulations that give some
insight into the structure of quantum mechanics and suggest possible reasons
why quantum mechanics might "have to be true". Some examples in this
category are many worlds, quantum logic, and Bohm's pilot wave. In the
second category are interpretations that want to be in the first category
but aren't there yet, like Penrose's ideas. In the third category are la-la
land ideas like "observer-created reality" that have no physically or
mathematically meaningful content at all.
Are there any experiments which most physicists agree can, or at least in
principle could, show us which interpretations are more true?
Some of the interpretations clarify the question of what exactly constitutes
a measurement, and to the extent that they clarify it in different ways, it
might be possible to test them against each other. I'm not too hopeful, though.
Many people talk about decoherence as a solution to the question of how a
wave function collapses. Assuming that this idea is tenable (or possibly
certainly true) would this favor any of the following interpretations, be
neutral to all of them, or perhaps suggest yet a different interpretation of
QM?
Decoherence is broadly accepted as mathematically correct and physically
real, so the fact that all the of usual interpretations have survived means
that at least their adherents don't think that decoherence has changed anything.
Nick Herbert talks about "Quantum Reality":
Quantum Reality #1 The Copenhagen Interpretation [...]
As described here, meaningless. But I don't think this is the Copenhagen
interpretation. In fact, I don't think there is a Copenhagen interpretation,
as such. These days the people who say that they subscribe to the Copenhagen
interpretation are the people who aren't interested in the whole debate.
Quantum Reality #3 - Reality is an undivided wholeness.
Meaningless.
Physicist David Bohm of London's Birkbeck College has especially stressed
the necessary wholeness of the quantum world...
Indeed he did, but fortunately his pilot wave ideas had enough mathematical
content to qualify as a meaningful interpretation. In the context of his
mathematical results, I can sort of understand what he meant by "wholeness",
even if I don't agree. The same is true of Bohr and Wheeler and so on. Their
comments make some sense in the appropriate context; otherwise, they're
meaningless.
Quantum Reality #4 The many-worlds interpretation. [...] In order to
accommodate different outcomes
without contradiction , entire new universes spring into being, identical in
every detail except for the single outcome that gave them birth.
Not an accurate description. The point of many worlds is that there's a
mechanism that leads to the worlds, and the mechanism is present in standard
quantum mechanics -- you don't have to add it.
Quantum Reality #5: Quantum logic (The World obeys a non-human kind of
reasoning.)
There's nothing non-human about quantum logic. It's just non-classical,
which simply means that it is not classical logic, classical logic being a
certain kind of logic that happens to be particularly well studied.
Quantum Reality #6. Neorealism (The world is made of ordinary objects.)
Meaningless.
Chief among neorealist rebels was Einstein, whose passion for
realism pitted him squarely against the quantum Orthodoxy...
Not true. Einstein's debate with Bohr was not about interpretations of QM;
it was about the logical consistency of the theory. Einstein lost the debate
because he was wrong: QM is logically consistent. If it had been a matter of
interpretation, the debate would never have been settled.
Einstein was indeed bothered by the fact that QM didn't make sense. /Every/
physicist is bothered by this. They all want to understand what QM is really
about.
Quantum Reality #7 Consciousness creates reality...
Meaningless.
...Eugene Wigner...comments on this ironic turn of events: "It is not
possible to formulate the laws of quantum mechanics in a fully consistent
way with out reference to the consciousness . . .
This is true only inasmuch as no physical theory can be formulated in a
consistent way without reference to our senses, hence to consciousness. It's
not any more true of quantum mechanics.
Quantum Reality #8. The duplex world of Werner Heisenberg (The world is
twofold, consisting of potentials and actualities.)
Meaningless.
-- Ben
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| User: "Sam Wormley" |
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| Title: Re: Interpreting Quantum Mechanics |
17 Oct 2005 12:34:37 AM |
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See: http://en.wikipedia.org/wiki/Interpretations_of_Quantum_Mechanics
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| User: "Gregory L. Hansen" |
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| Title: Re: Interpreting Quantum Mechanics |
17 Oct 2005 01:09:47 PM |
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You missed the transactional interpretation, which I sort of like. The
probability density is found by multiplying the wavefunction with its
complex conjugate, <psi|psi>. The time evolution operator is given by the
exponential of the Hamiltonian,
|psi(t)> = exp(-iHt/hbar) |psi(0)>
The complex conjugate has i -> -i and -i -> i,
<psi(t)| = <psi(0)| exp(iHt/hbar)
= <psi(0)| exp(-iH(-t)/hbar)
What's-his-name interpreted the complex conjugate as a wave going
backwards in time. Interactions going both forward and backward in time
negotiate a specific result. But they do so, e.g. through an entire
crystal before a particular trajectory is determined, so the long-range
order of a crystal determines the likelihood of particular trajectories
and we still get a diffraction pattern.
Many-worlds started to make more sense to me when I realized that the
"legs" of a Feynman diagram are arbitrary stopping points where particle
trajectories are classical enough for most purposes. Strictly speaking,
an interaction, a sensor, and an observer should be connected into one big
Feynman diagram. The measurement problem disappears when we stop
pretending that humans are classical entities that don't obey the laws of
quantum mechanics.
Mostly I just follow the "Shut up and calculate!" interpretation. I'm
usually more interested in what's going to happen than what it all means.
I suspect that those who are able to shut up calculate tend to do so,
while those that can't do so worry more about what it all means.
--
"The result of this experiment was inconclusive, so we had to use
statistics." (Overheard at international physics conference)
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| User: "Ben Rudiak-Gould" |
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| Title: Re: Interpreting Quantum Mechanics |
17 Oct 2005 04:04:11 PM |
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Gregory L. Hansen wrote:
What's-his-name interpreted the complex conjugate as a wave going
backwards in time. Interactions going both forward and backward in time
negotiate a specific result. But they do so, e.g. through an entire
crystal before a particular trajectory is determined, so the long-range
order of a crystal determines the likelihood of particular trajectories
and we still get a diffraction pattern.
I'm still trying to understand the transactional interpretation. All the
explanations I've read have been along the lines of what you wrote above,
and what you wrote above doesn't make sense to me. The problem is that there
seems to be an implicit second dimension of time -- I can't see any other
way to interpret the phrase "going backward in time", or the discussions of
what happens "before" and "after" a transaction completes. If the
interpretation /explicitly/ included a second dimension of time, that would
be fine. But when it's only implied, I get suspicious that what's-his-name
didn't notice it was there, and that the whole transaction idea isn't
actually mathematically well-defined.
-- Ben
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| User: "FrediFizzx" |
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| Title: Re: Interpreting Quantum Mechanics |
17 Oct 2005 04:59:08 PM |
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"Ben Rudiak-Gould" <br276deleteme@cam.ac.uk> wrote in message
news:dj13kc$db9$1@gemini.csx.cam.ac.uk...
| Gregory L. Hansen wrote:
| > What's-his-name interpreted the complex conjugate as a wave going
| > backwards in time. Interactions going both forward and backward in
time
| > negotiate a specific result. But they do so, e.g. through an entire
| > crystal before a particular trajectory is determined, so the
long-range
| > order of a crystal determines the likelihood of particular
trajectories
| > and we still get a diffraction pattern.
|
| I'm still trying to understand the transactional interpretation. All
the
| explanations I've read have been along the lines of what you wrote
above,
| and what you wrote above doesn't make sense to me. The problem is that
there
| seems to be an implicit second dimension of time -- I can't see any
other
| way to interpret the phrase "going backward in time", or the
discussions of
| what happens "before" and "after" a transaction completes. If the
| interpretation /explicitly/ included a second dimension of time, that
would
| be fine. But when it's only implied, I get suspicious that
what's-his-name
| didn't notice it was there, and that the whole transaction idea isn't
| actually mathematically well-defined.
Hmm... See Jay Yablon's preview article about the Dirac gamma^5 for a
possible clue about a "second dimension of time".
"Five Dimensional Spacetime with Axial Time, and the Geometric Origin of
Mass" at
http://home.nycap.rr.com/jry/FermionMass.htm
I kind of like the transactional interpretation coupled with a reduction
of "Many Worlds" to just two "worlds". Our "world" and what is
"outside" of ours. IOW, a dual spacetime concept with "our" Universe's
"now" being an event horizon between. However for me, relativistic
effects are a big clue as to why quantum theory is the way it is for
part of the interpretation.
FrediFizzx
http://www.vacuum-physics.com/QVC/quantum_vacuum_charge.pdf
or postscript
http://www.vacuum-physics.com/QVC/quantum_vacuum_charge.ps
http://www.vacuum-physics.com
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| User: "Gregory L. Hansen" |
|
| Title: Re: Interpreting Quantum Mechanics |
17 Oct 2005 09:22:08 PM |
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|
In article <dj13kc$db9$1@gemini.csx.cam.ac.uk>,
Ben Rudiak-Gould <br276deleteme@cam.ac.uk> wrote:
Gregory L. Hansen wrote:
What's-his-name interpreted the complex conjugate as a wave going
backwards in time. Interactions going both forward and backward in time
negotiate a specific result. But they do so, e.g. through an entire
crystal before a particular trajectory is determined, so the long-range
order of a crystal determines the likelihood of particular trajectories
and we still get a diffraction pattern.
I'm still trying to understand the transactional interpretation. All the
explanations I've read have been along the lines of what you wrote above,
and what you wrote above doesn't make sense to me. The problem is that there
seems to be an implicit second dimension of time -- I can't see any other
way to interpret the phrase "going backward in time", or the discussions of
what happens "before" and "after" a transaction completes. If the
interpretation /explicitly/ included a second dimension of time, that would
be fine. But when it's only implied, I get suspicious that what's-his-name
didn't notice it was there, and that the whole transaction idea isn't
actually mathematically well-defined.
-- Ben
I have to admit that I don't understand the transaction interpretation
except as the cartoonish explanation I gave above. And your problem is
reasonable. But then, who's to say there isn't a second time dimension?
I'm not the first person that wondered what we could do with a metric that
looks like
ds^2 = dx^2 + dy^2 + dz^2 - c^2 dt1^2 - c^2 dt2^2
--
"Awareness means not just a vague, comfortable, fuzzy feeling. It means
explicit knowledge of current conditions." -- NBSR Radiation Safety
Training
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