 |
|
|
|
|
|
| |
| |
|
|
|
|
| |
| |
|
|
scott wrote:
>>> If a cat's status is not decided until someone looks inside
>>
>> Since that isn't true, it's a meaningless question to ask.
>
> I thought the whole point of that experiment was that according to QM
> the cat was both alive and dead until you actually tried to look?
That's correct. But it's clearly not true, because the *cat* is observing
the situation, right? Of course the cat's status is decided by the cat
before anyone looks in the box, and thus there must be something wrong with
the concept that states remain in superposition until "observed." The point
was to ask "how observed does it need to be?"
I.e., the whole point of the experiment is to show how absurd it was to
think the QM "collapsed because it's observed" promoters were right.
--
Darren New, San Diego CA, USA (PST)
Human nature dictates that toothpaste tubes spend
much longer being almost empty than almost full.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Darren New wrote:
> scott wrote:
>>>> If a cat's status is not decided until someone looks inside
>>>
>>> Since that isn't true, it's a meaningless question to ask.
>>
>> I thought the whole point of that experiment was that according to QM
>> the cat was both alive and dead until you actually tried to look?
>
> That's correct. But it's clearly not true, because the *cat* is
> observing the situation, right? Of course the cat's status is decided by
> the cat before anyone looks in the box,
Who on Earth would let a cat decide anything? One whiff of catnip and it
would say whatever you wanted. ;)
>
> I.e., the whole point of the experiment is to show how absurd it was to
> think the QM "collapsed because it's observed" promoters were right.
>
That’s what I thought too.
--
Best Regards,
Stephen
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
scott <sco### [at] scott com> wrote:
> I thought the whole point of that experiment was that according to QM the
> cat was both alive and dead until you actually tried to look?
Not according to QM. According to the Copenhagen interpretation of it.
--
- Warp
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Darren New <dne### [at] sanrrcom> wrote:
> I.e., the whole point of the experiment is to show how absurd it was to
> think the QM "collapsed because it's observed" promoters were right.
That might have been the point of the experiment, but did it cause the
Copenhagen interpretation to be ditched, or is it still a "we don't know
for sure"?
--
- Warp
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> I.e., the whole point of the experiment is to show how absurd it was to
>> think the QM "collapsed because it's observed" promoters were right.
>
> That might have been the point of the experiment, but did it cause the
> Copenhagen interpretation to be ditched, or is it still a "we don't know
> for sure"?
As far as I know, they're still trying to figure out *why* the math works
like it does. Neeum posted this, which (after the Bell Inequality stuff at
the start indicating a need to consider this in the first place) discusses
the different possible view on the "why" of it all...
http://www.karlin.mff.cuni.cz/~motl/entan-interpret.pdf
Overall, I think some people are saying "if you're careful with the math,
it's obvious why it 'collapses'" but others obviously aren't so sure. Half
the people looking at the copenhagen interpretation think the wave is real
and half think it's just a way of looking at it mathematically, even so.
--
Darren New, San Diego CA, USA (PST)
Human nature dictates that toothpaste tubes spend
much longer being almost empty than almost full.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Warp wrote:
> scott <sco### [at] scottcom> wrote:
>> I thought the whole point of that experiment was that according to QM
the
>> cat was both alive and dead until you actually tried to look?
>
> Not according to QM. According to the Copenhagen interpretation of it
.
More technically, according to the math of the Schrödinger equation,
which
has no allowance for any non-QM events inside it. I.e., the math of QM
doesn't anywhere say "and at this point, you get quantum collapse." It's
trying to figure out why you *do* get quantum collapse that's the problem
.
--
Darren New, San Diego CA, USA (PST)
Human nature dictates that toothpaste tubes spend
much longer being almost empty than almost full.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On Mon, 07 Dec 2009 08:27:20 -0800, Darren New wrote:
> But it's clearly not true, because the *cat* is observing the situation,
> right?
Only if the cat's alive.... ;-)
Jim
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Stephen wrote:
>> I.e., the whole point of the experiment is to show how absurd it was
>> to think the QM "collapsed because it's observed" promoters were right.
>>
>
> That’s what I thought too.
>
Of course, the only flaw in the argument is that a cat isn't a particle,
so what effects *one* particle, doesn't effect something made of a *lot*
of them. This is the absurdity involved. Its like asking why relativity
doesn't work in black holes. Because its a bloody black hole, which has
different rules. In effect, QM is what goes on in single instances,
normal reality is an emergent property of what happens when QM can't
(or, if you prefer, the constraints put on the system reduce the
probability of a different result to near zero). Sort of like those
strange attractor images. Without the attractor, you don't get an image,
add one in, and the system gains constraints it didn't have before. Same
with particle interactions. Right?
--
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();
}
<A HREF='http://www.daz3d.com/index.php?refid=16130551'>Get 3D Models,
3D Content, and 3D Software at DAZ3D!</A>
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Patrick Elliott wrote:
> Of course, the only flaw in the argument is that a cat isn't a particle,
> so what effects *one* particle, doesn't effect something made of a *lot*
> of them.
Why not? Indeed, that *is* the flaw in the argument, but the question is
"why not?"
> This is the absurdity involved. Its like asking why relativity
> doesn't work in black holes. Because its a bloody black hole, which has
> different rules.
Relativity works just fine in black holes. That's why we know about them.
> In effect, QM is what goes on in single instances,
Single instances of what?
> normal reality is an emergent property of what happens when QM can't
> (or, if you prefer, the constraints put on the system reduce the
> probability of a different result to near zero).
Like what, in the case of the cat, specifically? A different result from
being alive or dead?
> Same with particle interactions. Right?
You tell me. You seem to have it all figured out so trivially.
--
Darren New, San Diego CA, USA (PST)
Human nature dictates that toothpaste tubes spend
much longer being almost empty than almost full.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Darren New wrote:
> Warp wrote:
>> Schrodinger's cat is a thought experiment, not an analogy.
>
> It's not even that hard to set up. :-)
I beg to differ -- AFAIK it's unbelievably difficult to put a box the
size of a cat into complete quantum isolation with the rest of a room.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
scott wrote:
>>> If a cat's status is not decided until someone looks inside
>>
>> Since that isn't true, it's a meaningless question to ask.
>
> I thought the whole point of that experiment was that according to QM
> the cat was both alive and dead until you actually tried to look? Maybe
> something changed since I read about it?
To be clear, strictly speaking this is not "according to QM" but rather
according to the Copenhagen Interpretation of QM (which is currently the
most popular interpretation of the mathematics).
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Kevin Wampler wrote:
> scott wrote:
>>>> If a cat's status is not decided until someone looks inside
>>>
>>> Since that isn't true, it's a meaningless question to ask.
>>
>> I thought the whole point of that experiment was that according to QM
>> the cat was both alive and dead until you actually tried to look?
>> Maybe something changed since I read about it?
>
>
> To be clear, strictly speaking this is not "according to QM" but rather
> according to the Copenhagen Interpretation of QM (which is currently th
e
> most popular interpretation of the mathematics).
I thought it was "according to the Schrödinger's wave equations"?
--
Darren New, San Diego CA, USA (PST)
Human nature dictates that toothpaste tubes spend
much longer being almost empty than almost full.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Darren New wrote:
>>> I thought the whole point of that experiment was that according to QM
>>> the cat was both alive and dead until you actually tried to look?
>>> Maybe something changed since I read about it?
>>
>>
>> To be clear, strictly speaking this is not "according to QM" but
>> rather according to the Copenhagen Interpretation of QM (which is
>> currently the most popular interpretation of the mathematics).
>
> I thought it was "according to the Schrödinger's wave equations"?
I should have checked to see that Warp had already written the same
thing I had, oh well.
At any rate, the relevant part of the wave equations here is really the
fact that they describe the probabilities of the outcomes of
measurements. In terms of "what's actually going on" any explanation
which can reproduce these probabilities is on equal footing WRT the
equations, and stating that the cat in superposition before measurement
and "collapses" when we open the box is only one such possible explanation.
Granted, it's worth noting (as you're aware) that the nature of QM puts
some pretty severe restrictions on what sorts of explanations can match
the observed measurements, but it's not as if the Copenhagen
Interpretation is the only possibility:
http://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Kevin Wampler wrote:
> At any rate, the relevant part of the wave equations here is really the
> fact that they describe the probabilities of the outcomes of
> measurements.
Right. And the question is "what's a measurement" in this case. That's the
outstanding question. Since measuring a superimposed state can give you an
answer different from any possible "outcome" per se, figuring out when a
"measurement" has occurred is the problem.
> and stating that the cat in superposition before measurement
> and "collapses" when we open the box is only one such possible explanation.
For us, maybe. Not for the cat.
--
Darren New, San Diego CA, USA (PST)
Human nature dictates that toothpaste tubes spend
much longer being almost empty than almost full.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Warp wrote:
> 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.
In general I agree with Neeum that it's not meaningful to discuss
weather it's a "wave" without defining what you even mean by a wave, but
I still thought I'd point out one way in which the "waves" in QM behave
differently from classical waves.
This was mentioned by Feynman in the short video linked by Darren, and
it's that in multiple particle systems the wave function doesn't just
describe the probability of finding a single particle at a given
position, but rather the probability of finding the entire system of
particles in a given configuration. This is distinct from the way that
classical waves behave, and is the source of effects of "non locality"
in quantum systems which would not arise from a system with classical waves.
If you want to still call this a wave (perhaps a wave in the
configuration space of the system?) then that's clearly fine, but it's
worth keeping in mind that it's a different sort of wave than one
generally means in classical systems.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Darren New wrote:
> Kevin Wampler wrote:
>> At any rate, the relevant part of the wave equations here is really
>> the fact that they describe the probabilities of the outcomes of
>> measurements.
>
> Right. And the question is "what's a measurement" in this case. That's
> the outstanding question. Since measuring a superimposed state can give
> you an answer different from any possible "outcome" per se, figuring out
> when a "measurement" has occurred is the problem.
Exactly why I phrased my sentence the way I did. The Schrödinger
equations don't directly say anything about what state the cat's in, or
even if it's in a deterministic state or not -- it's how you treat the
process of measurement that does, and that's a philosophical questions
rather than a scientific one at this point (and thus not part of QM
proper but of its interpretation).
More specifically, AFAIK there are some interpretations of QM which give
the cat a deterministic state, and others which don't (and I assume
others which regard the question as meaningless). All are in agreement
with he Schrödinger wave equation, so it's not the equation that's the
issue here.
>> and stating that the cat in superposition before measurement and
>> "collapses" when we open the box is only one such possible explanation.
>
> For us, maybe. Not for the cat.
Indeed, but I don't understand what this has to do with the Schrödinger
equations, since it seems (as I mentioned) to be only a problem with the
Copenhagen interpretation. Perhaps I'm missing what point you're making?
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Kevin Wampler wrote:
> If you want to still call this a wave (perhaps a wave in the
> configuration space of the system?) then that's clearly fine, but it's
> worth keeping in mind that it's a different sort of wave than one
> generally means in classical systems.
I think that's really the problem. When I say "it's not a wave", I'm saying
you don't get any of the same measurements from one particle that you'd get
from a wave. There's some wave-like stuff going on, but not in a way that
you'd normally say the photon *is* a wave.
For more fun confusion, what does multi-world say about stuff?
http://en.wikipedia.org/wiki/Quantum_suicide_and_immortality
--
Darren New, San Diego CA, USA (PST)
Human nature dictates that toothpaste tubes spend
much longer being almost empty than almost full.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Kevin Wampler wrote:
> All are in agreement
> with he Schrödinger wave equation, so it's not the equation that's
the
> issue here.
OK. I'm now more educated, I think.
> Indeed, but I don't understand what this has to do with the Schröd
inger
> equations, since it seems (as I mentioned) to be only a problem with th
e
> Copenhagen interpretation. Perhaps I'm missing what point you're makin
g?
Only that the quantum equations don't *seem* to apply to the macroscopic
world, for reasons unknown?
--
Darren New, San Diego CA, USA (PST)
Human nature dictates that toothpaste tubes spend
much longer being almost empty than almost full.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Darren New wrote:
> Kevin Wampler wrote:
>> All are in agreement with he Schrödinger wave equation, so it's not
>> the equation that's the issue here.
>
> OK. I'm now more educated, I think.
It's a point which is often neglected. Just to be clear though, the
issue is more subtle than I'm making it sound and AFAIK most
interpretations which give a deterministic state to the cat have run
into problems (for instance when incorporating them into special
relativity). Also such interpretations are necessarily non-local.
>> Perhaps I'm missing what point you're making?
>
> Only that the quantum equations don't *seem* to apply to the macroscopic
> world, for reasons unknown?
Yeah, IANAP (I am not a physicist) but as far as I'm aware this is
correct. Although I think there's some interpretations which describe
why this is the case perfectly well, they just might come with other
philosophical implications that are undesirable (for instance I'd put
the many-worlds interpretation into this class).
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Kevin Wampler wrote:
> Also such interpretations are necessarily non-local.
I read recently that someone did a Bell's Inequality type of experiment with
more than 20 angles measured in 3D and from that somehow deduced locality.
Interesting.
> Yeah, IANAP (I am not a physicist) but as far as I'm aware this is
> correct. Although I think there's some interpretations which describe
> why this is the case perfectly well, they just might come with other
> philosophical implications that are undesirable (for instance I'd put
> the many-worlds interpretation into this class).
Yah. I suspect it's much more mundane, like the "decoherence" section of the
paper Neeum posted.
--
Darren New, San Diego CA, USA (PST)
Human nature dictates that toothpaste tubes spend
much longer being almost empty than almost full.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Darren New wrote:
> Kevin Wampler wrote:
>> Also such interpretations are necessarily non-local.
>
> I read recently that someone did a Bell's Inequality type of experiment
> with more than 20 angles measured in 3D and from that somehow deduced
> locality. Interesting.
Do you have a reference to this? I'd be interested to see the details
of what exactly they mean by that.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Kevin Wampler wrote:
> Do you have a reference to this? I'd be interested to see the details
> of what exactly they mean by that.
I'm afraid that was before I started bookmarking everything that caught my
interest. :-) It was in something like Discover magazine, so there wasn't
much detail beyond what I already said in the article itself, but there
might have been links to the actual publication on the page.
--
Darren New, San Diego CA, USA (PST)
Human nature dictates that toothpaste tubes spend
much longer being almost empty than almost full.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Invisible wrote:
> http://en.wikipedia.org/wiki/File:Perseid_Meteor.jpg
>
> Here in the name of God does the night sky actually look like this?!
Anywhere far away from any major population center. In addition to
being able to see many more stars, I've found that you can also spot
about 10-30 shooting stars per hour in areas like that. It's quite
beautiful, and unfortunate that many people have always lived where you
simply can't see that sort of thing.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Darren New wrote:
> Patrick Elliott wrote:
>> Of course, the only flaw in the argument is that a cat isn't a
>> particle, so what effects *one* particle, doesn't effect something
>> made of a *lot* of them.
>
> Why not? Indeed, that *is* the flaw in the argument, but the question
> is "why not?"
>
>> This is the absurdity involved. Its like asking why relativity doesn't
>> work in black holes. Because its a bloody black hole, which has
>> different rules.
>
> Relativity works just fine in black holes. That's why we know about them.
>
>> In effect, QM is what goes on in single instances,
>
> Single instances of what?
>
>> normal reality is an emergent property of what happens when QM can't
>> (or, if you prefer, the constraints put on the system reduce the
>> probability of a different result to near zero).
>
> Like what, in the case of the cat, specifically? A different result
> from being alive or dead?
>
>> Same with particle interactions. Right?
>
> You tell me. You seem to have it all figured out so trivially.
>
No, what I am getting at is the math works in some specific cases, but
most of the time your particles are "not" in a state where that case
applies. That is what I mean about constraints. The cat, as a
collection, has constraints that an individual particle, in the test
cases, doesn't. After all, we don't throw cats are targets to measure
their QM, we generate single particles. And, no, that isn't bloody
trivial, any more than saying, "adding a strange attractor", tell you
what the result will actually look like. It just tells you it won't be
what you would have had *without it*. If I said A + B = QM, that would
be a "trivial" solution. 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();
}
<A HREF='http://www.daz3d.com/index.php?refid=16130551'>Get 3D Models,
3D Content, and 3D Software at DAZ3D!</A>
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Patrick Elliott wrote:
> No, what I am getting at is the math works in some specific cases, but
> most of the time your particles are "not" in a state where that case
> applies.
Why not? If the particle gets in that state, how does it get out of that
state? You can't just say "interaction" without giving specifics, since
"interaction with other particles" is exactly what QM defines. If it was
obvious that mere interactions with other particles resolved the problem,
the guy who invented the Schrödinger equations wouldn't have come up
with
the thought experiment in the first place.
What situations do particles get into where the QM equations don't apply?
Because every test seems to indicate we know the right *equations* to a
tremendous number of decimal places. You can't just say "it doesn't appl
y
sometimes" without saying the circumstances under which it doesn't.
> That is what I mean about constraints. The cat, as a
> collection, has constraints that an individual particle, in the test
> cases, doesn't.
That's the "decoherence" argument, if I understand you right. It's one of
many possible answers, but it's not obviously accepted by everyone involv
ed.
What constraint applies to many particles that doesn't apply to one,
according the the Schrödinger equations?
> After all, we don't throw cats are targets to measure
> their QM, we generate single particles.
Sure. But we look at distant stars to see the QM manifest in outer space.
We
generate Bose-einstein condensates bigger than a cat.
> It just tells you it won't be
> what you would have had *without it*.
Sorry. Pronoun overflow. What tells me what what wont be without what?
--
Darren New, San Diego CA, USA (PST)
Human nature dictates that toothpaste tubes spend
much longer being almost empty than almost full.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Darren New wrote:
>> It just tells you it won't be what you would have had *without it*.
>
> Sorry. Pronoun overflow. What tells me what what wont be without what?
>
What the result will be, without an attractor. As I said, I don't have a
math equation to explain it, but there obviously needs to be one, since,
under normal circumstances, as you say, you don't get non-decoherent
effects.
--
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();
}
<A HREF='http://www.daz3d.com/index.php?refid=16130551'>Get 3D Models,
3D Content, and 3D Software at DAZ3D!</A>
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Patrick Elliott wrote:
> What the result will be, without an attractor.
OK, I'm afraid you're not making any sense to me, so ... nevermind.
You're either completely missing my point, or you're talking about something
entirely different than what I am.
--
Darren New, San Diego CA, USA (PST)
Human nature dictates that toothpaste tubes spend
much longer being almost empty than almost full.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Darren New wrote:
> Patrick Elliott wrote:
>> What the result will be, without an attractor.
>
> OK, I'm afraid you're not making any sense to me, so ... nevermind.
>
> You're either completely missing my point, or you're talking about
> something entirely different than what I am.
>
I am saying that, in general principle, large masses of particles act
"similar" to what a strange attractor does for the images some people
have been making in povray.images. It changes the behavior of the
system. Until you plot the result, you don't necessarily have a
prediction of what that will be, but it "not" what you end up with if
you had one single particle. Mind, in reality, we have fairly clear
ideas what happens if you place x number of protons/neutrons and
electrons together, in a stable configuration, you end up with an
element or isotope.
None of which describes why, or how, trivially or otherwise, which is
the crux of your accusation.
--
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();
}
<A HREF='http://www.daz3d.com/index.php?refid=16130551'>Get 3D Models,
3D Content, and 3D Software at DAZ3D!</A>
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
