Patrick Elliott wrote:
> Ok. Already gave and answer to why this is odd, but.. Just to let you 
> clarify - How do you "measure" or "observe" what a particle as even 
> done, without colliding it with something?

You don't. But you can make a measurement after it has done something, and 
change what it "has done" already.

> definition, anything you can/do do, which looks at a particle, involves 
> *other particles*, 

Right. But it might involve *other* particles *after* the measurement of 
interest has been completed.

> Again, we can't measure/observe a particle, without interacting with it, 

Sure you can.  Look up Bell's Inequality, or Quantum Erasers.

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

> so claiming that "changing" it by observation differs from changing it 
> by hitting it with another particle is just... not making any sense at all.

That's what makes the copenhagen interpretation problematic, yes.


-- 
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   Human nature dictates that toothpaste tubes spend
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Darren New <dne### [at] sanrrcom> wrote:
> I think it's Occam's Razor here. Why postulate a quantum being a wave if (1) 
> no observation is capable of ever seeing it as a wave

  I suppose that means that all phenomena caused by electromagnetic waves
(which light is) has to be explained by non-wave means, such as for example
electromagnetic radiation having a frequency and amplitude, as well as
exhibiting wave-like behavior such as polarization (how can you polarize
a particle given that polarization is by definition a property of waves
that describes the orientation of their oscillations?) and the effect
electromagnetic waves have on electric conductors (which is what radio and
TV broadcasts, among many other things. are based on).

  The effect on eletric conductors is interesting: Electromagnetic waves
cause electrons to move at the same frequency than the frequency of the
incoming radiation, which clearly demonstrates that it does have a
frequency. The amount of movement is proportional to the amplitude of
the incoming radiation, which demonstrates that it does have an amplitude.
The amount of movement is also proportional to the direction of oscillation
of the incoming radiation (something which is also demonstrated by
polarization).

  The double-slit experiment also demonstrates wave-like quality.

  If it looks like a wave, feels like a wave, smells like a wave, what is it?
Not a wave, it seems. It just fakes being one quite well.

-- 
                                                          - Warp

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Patrick Elliott <sel### [at] npgcablecom> wrote:
> It was never intended to be used to imply that the 
> state in such a box could/does exist in the real world.

  AFAIK there's a big difference between an analogy and a thought experiment.

  An analogy is describing in layman terms something complicated. The analogy
is not to be taken literally, but just as a way to visualize the concept
being explained.

  A thought experiment, however, is something which should happen (even if
it's physically unfeasible to put into practice). It's not an analogy, but
an actual phenomenon which should happen if the theory is true and the proper
conditions could be set up.

  Schrodinger's cat is a thought experiment, not an analogy.

> And, if you think about it, it can't be otherwise. If you observe a 
> particle with a detector, the detector "causes" the state change.

  But in the thought experiment the detector already measured the radioactive
particle and caused (or not) the hammer to break the flask. The cat itself
also observes what happens (quite literally). Yet the thought experiment
still maintains that (given that the inside of the box is completely isolated
from the outside), the cat is in two superposed states. Not as an analogy or
figure of speech, but literally.

  If the solution were that simple, it wouldn't be a thought experiment
(with multiple possible explanations) at all.

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                                                          - Warp

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Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> I think it's Occam's Razor here. Why postulate a quantum being a wave if (1) 
>> no observation is capable of ever seeing it as a wave
> 
>   I suppose that means that all phenomena caused by electromagnetic waves
> (which light is)

I think it's not considered to be an electromagnetic wave any more.

> has to be explained by non-wave means, such as for example
> electromagnetic radiation having a frequency and amplitude, 

Yep. Explained.

> as well as
> exhibiting wave-like behavior such as polarization (how can you polarize
> a particle given that polarization is by definition a property of waves
> that describes the orientation of their oscillations?)

Not in QM. I don't know too much about polarization, but it's not purely 
based on "wave" stuff.

> and the effect
> electromagnetic waves have on electric conductors (which is what radio and
> TV broadcasts, among many other things. are based on).

Sure. Particles of light hitting the metal of the antenna and knocking 
electrons around causes radio reception, for example.

>   The effect on eletric conductors is interesting: Electromagnetic waves
> cause electrons to move at the same frequency than the frequency of the
> incoming radiation, which clearly demonstrates that it does have a
> frequency. 

The change in quantum-amplitude has a frequency, because you're changing it 
in a regular pattern at the transmitter.

> The amount of movement is proportional to the amplitude of
> the incoming radiation, 

It's proportional to the number of photons arriving. If by "amplitude" you 
mean "strength", then yes. If by "amplitude" you mean what people who talk 
about QED mean, then no.

 > which demonstrates that it does have an amplitude.
> The amount of movement is also proportional to the direction of oscillation
> of the incoming radiation (something which is also demonstrated by
> polarization).
> 
>   The double-slit experiment also demonstrates wave-like quality.
> 
>   If it looks like a wave, feels like a wave, smells like a wave, what is it?
> Not a wave, it seems. It just fakes being one quite well.

As I said, the probability of finding a particle in a particular place is 
based on multiplying complex numbers. But since you never actually find a 
wave, but only interference patterns (so to speak), it's probably not a 
wave.  The "wave" properties don't explain *all* the different kinds of 
interference, but only the kinds that interfere like waves do. There's also 
interference patterns that are the opposite of what you'd get with waves 
(lasing vs exclusion principle) that is *also* explained by the theory in 
which everything is a particle.

You really should watch the lectures (or read the book) I pointed you to. 
They do a very nice job of explaining it. Both the video and the book are 
Feynman, who got a nobel prize for figuring out how to explain to other 
quantum physicists how to figure out wtf is going on with quantum mechanics, 
so it's really quite interesting.

-- 
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   Human nature dictates that toothpaste tubes spend
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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."

-- 
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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On 12/02/09 19:06, Darren New wrote:
>> I suppose that means that all phenomena caused by electromagnetic waves
>> (which light is)
>
> I think it's not considered to be an electromagnetic wave any more.

	Throughout this thread (which I admit I did not read all of), you've 
stated stuff a bit too definitively for my taste, as if all the top 
physicists agree on this.

	I can only abuse David Mermin's quote: "Shut up and calculate!"

	I'm guessing that the actual mathematical formalism that we have for QM 
addresses all that is _needed_, in that it always works, and we know of 
no phenomenon (except perhaps gravity) that our mathematical formalism 
fails at. Given that, having an argument about whether it's a wave or a 
particle is philosophy of the pointless kind. The theory will remain 
unchanged.

	I'm truly baffled as to why y'all are arguing so much about this.

	*Knowing* that it's a particle or a wave is not (as far as anyone 
knows) going to change physics, or its rules, or even give better 
results, or allow you to do better calculations. I'm not even sure if 
any of you has bothered to *define* what a particle is or what a wave 
is. Without doing so, the argument becomes even more amusing - 
especially considering that what an electron/photon is may truly not fit 
either one.

	Which is likely the view I favor: Notions of particles and waves for 
things like photons and electrons are somewhat meaningless Heck, a wave 
was "meaningless" for light even before QM was known - what is it waving 
in? I'm sure some of your (Darren's) arguments against viewing it as a 
wave were as applicable in the 1800's, before QM came around.

	Particles/waves, to me, are macroscopic phenomena. Photons and 
electrons are described accurately by the mathematical rules in QM. 
That's all there is. There's really nothing more to know about it. We 
know as much as there is to know about QM as we did classical mechanics. 
Ultimately, the latter was also properly described by a mathematical 
formalism. 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.

	(OK, I may be exaggerating a tiny bit in the last paragraph, but the 
main point is that just because it seems "weird" doesn't mean it's any 
weirder than classical mechanics).

>> as well as
>> exhibiting wave-like behavior such as polarization (how can you polarize
>> a particle given that polarization is by definition a property of waves
>> that describes the orientation of their oscillations?)
>
> Not in QM. I don't know too much about polarization, but it's not purely
> based on "wave" stuff.

	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.

> You really should watch the lectures (or read the book) I pointed you
> to. They do a very nice job of explaining it. Both the video and the
> book are Feynman, who got a nobel prize for figuring out how to explain
> to other quantum physicists how to figure out wtf is going on with
> quantum mechanics, so it's really quite interesting.

	I haven't read the book, but my physics professor said that it's THE 
book to read (QED) if you want to get an understanding of light/EM 
phenomenon.

-- 
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Neeum Zawan wrote:
>     Throughout this thread (which I admit I did not read all of), you've 
> stated stuff a bit too definitively for my taste, as if all the top 
> physicists agree on this.

I'm just stating my understanding of the general consensus. I freely 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. :-)

>     I'm guessing that the actual mathematical formalism that we have for 
> QM addresses all that is _needed_, in that it always works, and we know 
> of no phenomenon (except perhaps gravity) that our mathematical 
> formalism fails at. 

The other quantum stuff is similar but not identcail formulas, yes.

> Given that, having an argument about whether it's a 
> wave or a particle is philosophy of the pointless kind. The theory will 
> remain unchanged.

Yep.

> any of you has bothered to *define* what a particle is or what a wave 
> is. 

Well, I tried to indirectly describe things a wave would do that a particle 
doesn't, but yeah.

> 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.

>     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.

>     I haven't read the book, but my physics professor said that it's THE 
> book to read (QED) if you want to get an understanding of light/EM 
> phenomenon.

Yep. It's awesome, explained by the guy who invented the way to calculate 
the stuff *based* on the explanation. The link to the videos is Feynman 
presenting the lectures that got edited into the book, which is also 
fascinating.

-- 
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 wrote:
> 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."
> 

One tends to suspect that, as a thought experiment, it runs into the 
same problem as Zeno's Paradox. Which is to say, there is some specific 
minimum interaction/time frame/minimal distance, or what ever, in which 
something either does *or* doesn't happen, and you can't have it be both 
at the same time. In Zeno's case, there is literally a very small, but 
provable, distance that you *must* move, if you move at all, and 
crossing that line eliminates the paradox (in this case, probably 
something like the closest you can get to another particle, without it 
nudging the other particle, or something to that effect). They have 
already proven, using QM experiments, that they *is* such a limit with 
time, and that *before* that point you can nudge a particle back into 
what ever state it had prior to measurement, but, anything after that 
you are stuck with what ever the prior interaction gave you. The 
previous assumption was that such events where instantaneous, and no 
such micro-time event was possible.

Thus, the thought experiment is flawed, unless, as I said, you assume 
that the entire box, everything in it, and thus what it does, is all 
*one* object. A classic case of, "Of course a tree makes a sound if it 
falls in an empty forest with no one to see it." The flaw is the 
assumption that *someone* has to look into the box. I am not sure how to 
put it.. Basically, its like astrology. Imagining that just because a 
lot of big stuff is wandering around the universe, the small stuff 
**must** be so drastically influenced by it that a cat can actually *be* 
in such an indeterminate state. Not so. 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, in which 
case we might as well start talking to priest and gurus about 
transcendentalism, and give up on physics.

Yeah, there are some goofy theories that sort of allow for it, but most 
of them are notable in that they have to do things like throwing out 
time, without having any damn math, never mind real theory, about how to 
replace it with something that still *acts* like time from our view. Its 
one thing to propose a thought experiment, its another to invent an 
entire branch of, "this will fill in all the holes, I promise", 
'science', which consists of no concrete data, experiments, theories, or 
plausible mechanisms, and amounts to nothing *but* a long list of 
thought experiments.

People tried that once before. It was called Alchemy, and, within its 
own, flawed and incorrect, framework, everything known at the time 
"worked" by its rules, including the math involved. It would be nice of 
we at least tried to stick with dealing with the universe we can 
observe, instead of wandering off into 50,000 of them we can't, trying 
to find some weird sort of universe that would **look like** ours, if 
stuck inside it. Not even string theory gets that odd, most of the time, 
and it, so far, is about as useful at explaining anything as staring at 
a something like the "accidental isosuface" thread is *actually* an 
accurate method of predicting planet formation.

It might lead some place, maybe. At the moment, even some of the people 
that wanted it to lead some place are looking at those studying the math 
and thinking, "Ok, so... when are we going to get a theory, never mind 
actual useful data, out of this 'science'?" lol

-- 
void main () {
   If Schrödingers_cat is alive or version > 98 {
     if version = "Vista" {
       call slow_by_half();
       call DRM_everything();
     }
     call functional_code();
   }
   else
     call crash_windows();
}

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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

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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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