On 12/02/09 22:15, Darren New wrote:
> I'm just stating my understanding of the general consensus. I freely

	The only real consensus is on the mathematical formalism. It wouldn't 
surprise me if most physicists I've interacted would either say "acts 
like both a particle or a wave, so it's both" or simply say "it's 
neither, and don't waste time thinking about it".

	Take the two Nobel laureates here:

"The 29 December 2005 edition of the International Herald Tribune 
printed an article, "New tests of Einstein's 'spooky' reality", which 
referred to Leggett's Autumn 2005 debate at a conference in Berkeley, 
California, with fellow Nobel laureate Norman Ramsey of Harvard 
University.[5] Both debated the worth of attempts to change quantum 
theory. Leggett thought attempts were justified, Ramsey opposed. Leggett 
believes quantum mechanics may be incomplete because of the quantum 
measurement problem."

	(From Leggett's Wikipedia page). His stance is interesting, as there 
was another well known physicist (not a Nobel Laureate, but a member of 
the NAS nevertheless) who argued that the derivation of the Bell's 
Inequalities used arguments/theorems from statistics which, while 
correct, were more limited in scope than most physicists think, and he 
believed it wasn't sufficient enough to completely counter the notion of 
hidden variables.

	The "interesting" thing was that Leggett, who himself has issues with 
the whole quantum measurement problem, thought this third guy was a 
quack (on this topic, not as a physicist as a whole).

	Physicists _do_ disagree. They probably only agree that it's 
irrelevant.<G>

> admit that maybe they're wrong, but when the guy who got the nobel prize
> for explaining to other theoretical pysicists how it works says "It's
> never ever a wave", I'm gonna go with his explanation. :-)

	Well, sure. And I don't doubt that many physicists including Nobel 
Laureates disagree. And they're free to, because it is now in the realm 
of philosophy. The theory won't change either way. I don't think any one 
so far has come up with a "Well if we could show that it's REALLY a 
wave/particle (whatever that means), then we'd have this phenomenon that 
QM doesn't already predict".

	I guess I mean to say that I doubt you can scientifically demonstrate 
(i.e. with repeatable experiments) that it is truly a particle or truly 
a wave or truly both. And if you did, I bet that you merely defined 
particle/wave/both to be whatever the outcome of the experiment is.

>> We had an illusion that we understood that better merely because we
>> were used to it in our daily lives. But that's just an illusion.
>
> True. It's like asking *why* there are three dimensions, or *why* you
> subtract the square of time instead of adding it in GR.

	Precisely.

>> In general, are you sure polarization cannot be described just by
>> waves? If you have waves in 3-D materials? FYI, the standard model for
>> sound waves in solids (i.e. phonons) assumes they have a polarization.
>
> I think the effect of polarization of quanta does stuff that
> polarization based entirely on the directions of waves can't do, like
> lasing and fermion exclusion.

	Except that there's nothing fundamental in physics that doesn't allow 
lasing with phonons instead of photons. God simply didn't give us solids 
with the proper material properties that would allow it easily, and no 
one has figured out a way to engineer such solids. See

http://en.wikipedia.org/wiki/Sound_Amplification_by_Stimulated_Emission_of_Radiation

	The theory of phonons is almost identical to that of photons. Discrete, 
energy packets of energy h*f, that can be absorbed/emitted by particles 
like electrons. The math is quite similar. It's just that photons are 
fundamental particles, and phonons, well, don't seem to be. They're just 
atomic/ionic vibrations in a crystal lattice, and some kinds of phonons 
are responsible for sound in solids.

	Don't know what you mean by fermion exclusion. Maybe it was in another 
message. You mean as in the Pauli exclusion? If so, I was referring to 
photons and making the analogy, where Pauli exclusion doesn't apply.

PS - Apparently some people did claim to produce a phonon laser a few 
months ago. I should try to see if I can make any sense of their paper...

http://today.caltech.edu/today/story-display-blurb?story_id=38363

-- 
Americans are getting stronger. Twenty years ago, it took two people to 
carry ten dollars' worth of groceries. Today, a five-year-old can do it.

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Patrick Elliott wrote:
> Either *any* interacting causes 
> a state change, in which case the cat *must* be in a known state 
> already, or nothing is, including the poor deluded fool worrying about 
> whether or not he killed the neighbors cat in the experiment, 

Except that's exactly the point. The math says it's the latter case. And the 
cat experiment is to point out how absurd that conclusion is. Hence, the 
math must be mistaken.

-- 
Darren New, San Diego CA, USA (PST)
   Human nature dictates that toothpaste tubes spend
   much longer being almost empty than almost full.

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Darren New <dne### [at] sanrrcom> wrote:
> As I said, the probability of finding a particle in a particular place is 
> based on multiplying complex numbers.

  Btw, I find it curious how you use the mathematical models as some kind
of evidence that photons are not waves. After all, Feynman himself stressed
that his formulation is merely a mathematical description, not an attempt to
describe a real process that we cannot meassure.

-- 
                                                          - Warp

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Darren New <dne### [at] sanrrcom> wrote:
> Warp wrote:
> >   Schrodinger's cat is a thought experiment, not an analogy.

> It's not even that hard to set up. :-)

> I think the point is that you have to question what an "observation" is. If 
> the particle gets emitted and runs into the detector when the power is 
> turned off, is it "observed"?  If the power is on but the detector isn't 
> connected to anything?  If it's connected to a speaker you can't hear? If 
> it's connected to poison but there's no cat in the box?  Etc?

> In other words, if it takes an "observer" to collapse the wave function, is 
> the cat enough of an "observer" to count? If so, how does the human get 
> involved? According to the math, the cat is still superimposed. But that 
> would imply the cat isn't sufficiently an observer to cause the collapse. 
> *Or* that the math doesn't match reality. And multi-worlds is an attempt to 
> say "no, the math really matches reality."

  AFAIK those are the things Erwin Schr?dinger questioned about the
Copenhagen interpretation with his now-famous thought experiment.

-- 
                                                          - Warp

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Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> As I said, the probability of finding a particle in a particular place is 
>> based on multiplying complex numbers.
> 
>   Btw, I find it curious how you use the mathematical models as some kind
> of evidence that photons are not waves.

I believe you misunderstand me. I'm saying we never observe a wave. We just 
observe math that's the same math as a wave. That isn't what makes it "not a 
wave", that's what makes people used to think (and some people still think) 
it was a wave. :-)

I.e., just the opposite. The mathematical model is *not* evidence it's a 
wave, any more than the interference patterns are.

-- 
Darren New, San Diego CA, USA (PST)
   Human nature dictates that toothpaste tubes spend
   much longer being almost empty than almost full.

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Warp wrote:
>   AFAIK those are the things Erwin Schr?dinger questioned about the
> Copenhagen interpretation with his now-famous thought experiment.

Yes. I'm agreeing with you, and hopefully adding some more to the discussion.

-- 
Darren New, San Diego CA, USA (PST)
   Human nature dictates that toothpaste tubes spend
   much longer being almost empty than almost full.

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Darren New <dne### [at] sanrrcom> wrote:
> I.e., just the opposite. The mathematical model is *not* evidence it's a 
> wave, any more than the interference patterns are.

  I don't really know your definition of "evidence", but as I understand it,
the interference pattern *is* evidence for it to be wave. It's not *proof* of
it, but evidence is no proof anyways.

-- 
                                                          - Warp

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> Except that's exactly the point. The math says it's the latter case. And 
> the cat experiment is to point out how absurd that conclusion is. Hence, 
> the math must be mistaken.

What happens if you shut the double-slit experiment away in a box, with 
photon detector attached to each slit?  Will the interference pattern still 
be generated?

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scott wrote:
>> Except that's exactly the point. The math says it's the latter case. 
>> And the cat experiment is to point out how absurd that conclusion is. 
>> Hence, the math must be mistaken.
> 
> What happens if you shut the double-slit experiment away in a box, with 
> photon detector attached to each slit?  Will the interference pattern 
> still be generated?

No.  Worse, check out this:

http://en.wikipedia.org/wiki/Wheeler%27s_delayed_choice_experiment

Basically, the photon behaves differently even if you measure it *after* it 
has passed through the slits. Which is why it's pretty safe to assume it's 
not "going thru both slits" when you get the interference pattern.

http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser

This one changes whether the photon went thru one or both slits *after* it 
has already been detected. Hard to see how that's the behavior of a wave 
that passes through both slits.

-- 
Darren New, San Diego CA, USA (PST)
   Human nature dictates that toothpaste tubes spend
   much longer being almost empty than almost full.

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>> What happens if you shut the double-slit experiment away in a box, with 
>> photon detector attached to each slit?  Will the interference pattern 
>> still be generated?
>
> No.  Worse, check out this:
>
> http://en.wikipedia.org/wiki/Wheeler%27s_delayed_choice_experiment
>
> Basically, the photon behaves differently even if you measure it *after* 
> it has passed through the slits. Which is why it's pretty safe to assume 
> it's not "going thru both slits" when you get the interference pattern.

But put the whole thing inside a big closed box so nobody can observe the 
patterns (exactly like the cat in a box setup).  If a cat's status is not 
decided until someone looks inside (even though there is a particle detector 
and related mechanisms inside) then why should the interference pattern not 
be there if nobody is observing it?

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