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.

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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

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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.

-- 
                                                          - Warp

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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

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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.

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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.

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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

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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();
}

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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.

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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.

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