On 9/16/2011 8:19, Warp wrote:
> Darren New<dne### [at] sanrrcom>  wrote:
>> On 9/14/2011 11:46, Alain wrote:
>>> Shroeder's cat is always both dead and alive untill someone does observe it.
>
>> I think most people miss the point of this question, which is to ask whether
>> the *cat* observes itself.
>
>    Isn't the interpretation such that the state of the particle/molecule/cat
> is relative, not absolute?

That's another question the cat raises, yes.

The idea was not "LOL, the cat can't be alive and dead at the same time so 
you're obviously wrong", which is how most people interpret it. The question 
is what causes the "collapse" if the right answer is "observation".

>    I think that the question presented by the original thought experiment is
> that, if quantum superposition is indeed the correct interpretation, whether
> such superpositions apply to macroscopic objects.

I don't think there's any question any more that they apply to macroscopic 
objects. At the time the question was raised, sure, maybe.

But at what point and for what reason wouldn't they apply?

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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Le 2011/09/16 11:27, Warp a écrit :
> Jim Holsenback<nom### [at] nomailcom>  wrote:
>> You guys are cracking me up here ... this thread started as a purely
>> tongue in cheek observation of nocturnal posting habits. I'm amazed at
>> the over analysis that's going on now. Have mercy ... some of you could
>> drain every ounce of fun out of a rousing game of trivial pursuit.
>
>    Nothing is funnier than overanalyzing things.
>

Entirely true! :)

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Darren New <dne### [at] sanrrcom> wrote:
> But at what point and for what reason wouldn't they apply?

  For the same reason that if you kick footballs towards a wall with
two slits on it (slightly wider than the football), you don't get a
diffraction pattern on a wall behind it where the balls hit.

-- 
                                                          - Warp

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On 16/09/2011 5:37 PM, Alain wrote:
> Le 2011/09/16 11:27, Warp a écrit :
>> Jim Holsenback<nom### [at] nomailcom> wrote:
>>> You guys are cracking me up here ... this thread started as a purely
>>> tongue in cheek observation of nocturnal posting habits. I'm amazed at
>>> the over analysis that's going on now. Have mercy ... some of you could
>>> drain every ounce of fun out of a rousing game of trivial pursuit.
>>
>> Nothing is funnier than overanalyzing things.
>>
>
> Entirely true! :)
>

Are you sure that it is entirely true?

-- 
Regards
     Stephen

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On 9/16/2011 9:49, Warp wrote:
> Darren New<dne### [at] sanrrcom>  wrote:
>> But at what point and for what reason wouldn't they apply?
>
>    For the same reason that if you kick footballs towards a wall with
> two slits on it (slightly wider than the football), you don't get a
> diffraction pattern on a wall behind it where the balls hit.

Yes you do. It's just that the diffraction pattern is very, very fine. 
Probably finer than you can actually measure. But theoretically it's there.

However, even if you were correct, that doesn't answer the question. The 
point of S's cat is to show that the answer is not "they don't apply because 
I observed the result."

You're aware of Bose-Einstein condensates, right? And you're aware they've 
actually been made out of elementary particles larger than the entire room 
they're centered in?  Size has little if anything to do with it.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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Le 2011/09/16 12:49, Stephen a écrit :
> On 16/09/2011 5:37 PM, Alain wrote:
>> Le 2011/09/16 11:27, Warp a écrit :
>>> Jim Holsenback<nom### [at] nomailcom> wrote:
>>>> You guys are cracking me up here ... this thread started as a purely
>>>> tongue in cheek observation of nocturnal posting habits. I'm amazed at
>>>> the over analysis that's going on now. Have mercy ... some of you could
>>>> drain every ounce of fun out of a rousing game of trivial pursuit.
>>>
>>> Nothing is funnier than overanalyzing things.
>>>
>>
>> Entirely true! :)
>>
>
> Are you sure that it is entirely true?
>

To be honest, it also depends on who you ask about that. But is's still fun.

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Darren New <dne### [at] sanrrcom> wrote:
> On 9/16/2011 9:49, Warp wrote:
> > Darren New<dne### [at] sanrrcom>  wrote:
> >> But at what point and for what reason wouldn't they apply?
> >
> >    For the same reason that if you kick footballs towards a wall with
> > two slits on it (slightly wider than the football), you don't get a
> > diffraction pattern on a wall behind it where the balls hit.

> Yes you do. It's just that the diffraction pattern is very, very fine. 
> Probably finer than you can actually measure. But theoretically it's there.

  The diffraction pattern isn't there even with elemental particles if you
measure which slit the particles go through.

  How do you set up a situation where it's not possible to tell which slit
the football went through? I don't think it's physically possible.

  You could perhaps try having the experiment in an absolute vacuum (something
which is already very hard), and in an environment with no electromagnetic
radiation of any kind, that could hit the ball and tell its trajectory
(maybe it would be theoretically possible, but I'm not sure it is in
practice). Also anything else that could hit the ball and hence possibly
tell its trajectory (eg. neutrinos and cosmic rays) would have to be
completely absent.

  In fact, thinking about it. would the ball and the walls themselves emit
photons that could tell the trajectory? Are they black body radiators?
I suppose that if that's the case, the ball and the walls would have to be
cooled to absolute zero to stop them from emitting any particles.

  So let's see, absolute vacuum, complete isolation from external
electromagnetic radiation and other particles (such as neutrinos and
cosmic rays), and the objects cooled to absolute zero to stop them from
emitting any particles.

  But is that enough? What about vacuum energy? Virtual particles that
pop up into existence spontaneously, hitting the ball? Could they be used
to measure its trajectory?

  Even if *all* of those things were somehow taken care of, would there
be an interference pattern?

  If yes, what explains the deviation in the trajectory of the ball?
One of the fundamental interactions (gravity, electromagnetism, strong
interaction, weak interaction)? How can they deviate the ball so much?

-- 
                                                          - Warp

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On 16/09/2011 6:16 PM, Alain wrote:
> Le 2011/09/16 12:49, Stephen a écrit :
>> On 16/09/2011 5:37 PM, Alain wrote:
>>> Le 2011/09/16 11:27, Warp a écrit :
>>>> Jim Holsenback<nom### [at] nomailcom> wrote:
>>>>> You guys are cracking me up here ... this thread started as a purely
>>>>> tongue in cheek observation of nocturnal posting habits. I'm amazed at
>>>>> the over analysis that's going on now. Have mercy ... some of you
>>>>> could
>>>>> drain every ounce of fun out of a rousing game of trivial pursuit.
>>>>
>>>> Nothing is funnier than overanalyzing things.
>>>>
>>>
>>> Entirely true! :)
>>>
>>
>> Are you sure that it is entirely true?
>>
>
> To be honest, it also depends on who you ask about that. But is's still
> fun.

Honesty is the best policy, I've been told. :-)

-- 
Regards
     Stephen

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Le 2011/09/16 13:33, Warp a écrit :
> Darren New<dne### [at] sanrrcom>  wrote:
>> On 9/16/2011 9:49, Warp wrote:
>>> Darren New<dne### [at] sanrrcom>   wrote:
>>>> But at what point and for what reason wouldn't they apply?
>>>
>>>     For the same reason that if you kick footballs towards a wall with
>>> two slits on it (slightly wider than the football), you don't get a
>>> diffraction pattern on a wall behind it where the balls hit.
>
>> Yes you do. It's just that the diffraction pattern is very, very fine.
>> Probably finer than you can actually measure. But theoretically it's there.
>
>    The diffraction pattern isn't there even with elemental particles if you
> measure which slit the particles go through.
>
>    How do you set up a situation where it's not possible to tell which slit
> the football went through? I don't think it's physically possible.
>
>    You could perhaps try having the experiment in an absolute vacuum (something
> which is already very hard), and in an environment with no electromagnetic
> radiation of any kind, that could hit the ball and tell its trajectory
> (maybe it would be theoretically possible, but I'm not sure it is in
> practice). Also anything else that could hit the ball and hence possibly
> tell its trajectory (eg. neutrinos and cosmic rays) would have to be
> completely absent.
>
>    In fact, thinking about it. would the ball and the walls themselves emit
> photons that could tell the trajectory? Are they black body radiators?
> I suppose that if that's the case, the ball and the walls would have to be
> cooled to absolute zero to stop them from emitting any particles.
>
>    So let's see, absolute vacuum, complete isolation from external
> electromagnetic radiation and other particles (such as neutrinos and
> cosmic rays), and the objects cooled to absolute zero to stop them from
> emitting any particles.
>
>    But is that enough? What about vacuum energy? Virtual particles that
> pop up into existence spontaneously, hitting the ball? Could they be used
> to measure its trajectory?
>
>    Even if *all* of those things were somehow taken care of, would there
> be an interference pattern?
>
>    If yes, what explains the deviation in the trajectory of the ball?
> One of the fundamental interactions (gravity, electromagnetism, strong
> interaction, weak interaction)? How can they deviate the ball so much?
>

I remember a day in my physics class when we where studying waves. We 
had to calculate the effective wave lenght of common, macroscopic, objects.
It depended on mass and dimentions, both tending to give smaller values 
as they get larger.

For a footbal, it would be in the 10e-20 to 10e-30 m range. So, your 
interference pattern would be smaller than a proton.

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Alain <aze### [at] qwertyorg> wrote:
> For a footbal, it would be in the 10e-20 to 10e-30 m range. So, your 
> interference pattern would be smaller than a proton.

  That starts being awfully close to the planck length.

-- 
                                                          - Warp

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On 9/16/2011 10:33, Warp wrote:
>    The diffraction pattern isn't there even with elemental particles if you
> measure which slit the particles go through.

It's a little more complicated than that, really.

>    How do you set up a situation where it's not possible to tell which slit
> the football went through? I don't think it's physically possible.

The same way you do it with electrons or photons or whatever. You don't look.

>    You could perhaps try having the experiment in an absolute vacuum (something
> which is already very hard), and in an environment with no electromagnetic
> radiation of any kind, that could hit the ball and tell its trajectory
> (maybe it would be theoretically possible, but I'm not sure it is in
> practice). Also anything else that could hit the ball and hence possibly
> tell its trajectory (eg. neutrinos and cosmic rays) would have to be
> completely absent.

Not really. You get the diffraction/interference pattern even with photons 
going through air, so there's no reason to expect a football going through 
air is going to be more affected.

>    In fact, thinking about it. would the ball and the walls themselves emit
> photons that could tell the trajectory? Are they black body radiators?
> I suppose that if that's the case, the ball and the walls would have to be
> cooled to absolute zero to stop them from emitting any particles.

It's not a question of emitting particles or not. It's a question of whether 
you *measure* whether they're emitted.

>    If yes, what explains the deviation in the trajectory of the ball?

That's just how the quantum world works. The same explanation you give for 
photons or electrons applies to footballs, as far as I know (or as far as 
anyone knows, last I heard).

> One of the fundamental interactions (gravity, electromagnetism, strong
> interaction, weak interaction)?

Well, for the football, it would be quantum electrodynamics, which is the 
interaction of photons with electrons.

> How can they deviate the ball so much?

Remember that the diffraction pattern is going to be on the same scale as 
the wavelength of the football. The wavelength of the football is 
exceedingly tiny, quite possibly smaller than a proton, for example. So it 
doesn't take a large deviation.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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On 9/16/2011 11:23, Warp wrote:
> Alain<aze### [at] qwertyorg>  wrote:
>> For a footbal, it would be in the 10e-20 to 10e-30 m range. So, your
>> interference pattern would be smaller than a proton.
>
>    That starts being awfully close to the planck length.

I guess if 15 orders of magnitude is "awfully close"... :-)

I do wonder how big something would have to be for the wavelength to be 
close to the planck length.  It would be cool if that was, like, close to 
the size of the observable universe.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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Darren New <dne### [at] sanrrcom> wrote:
> It's not a question of emitting particles or not. It's a question of whether 
> you *measure* whether they're emitted.

  Those particles are going to hit something. It's very unlikely that they
will go to the end of the universe without hitting anything.

  Now, how does the football (or atom, or particle) "know" that what those
emitted particles hit is not "measurement"? Does it make a conscious
decision like "yeah, these particles are not being measured by any conscious
mind, nor any device which would record the difference, so it's safe for
me to do the interference dance"? How does the traveling object know the
difference between those emitted particles hitting a rock or hitting a
measurement device that can tell the difference?

  Or is it the *interaction* between the traveling object and the particles
that hit it (or which it emits), particles that *could* be used to measure
which slit the object went through, that makes the difference?

-- 
                                                          - Warp

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Am 14.09.2011 20:46, schrieb Alain:
> Le 2011/09/14 04:44, Invisible a écrit :
>>>> It ALWAYS make a _sound_.
>>>
>>> How do you know?
>>
>> If Schroeder's cat dies and no one observes it, is it still dead?
>
> Shroeder's cat is always both dead and alive untill someone does observe
> it. Then, the cat is ether alive or dead.

http://cheezburger.com/View/5209969152

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Le 2011/09/16 14:23, Warp a écrit :
> Alain<aze### [at] qwertyorg>  wrote:
>> For a footbal, it would be in the 10e-20 to 10e-30 m range. So, your
>> interference pattern would be smaller than a proton.
>
>    That starts being awfully close to the planck length.
>

We ended up with much smaller values:
A person, around 10e-50.
A medium car, around 10e-75.
The Earth, in the 10e-200 range.

I don't remember the formula and don't think that I still have it, after 
over 30 years ;)

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Le 2011/09/16 16:31, Darren New a écrit :
> On 9/16/2011 11:23, Warp wrote:
>> Alain<aze### [at] qwertyorg> wrote:
>>> For a footbal, it would be in the 10e-20 to 10e-30 m range. So, your
>>> interference pattern would be smaller than a proton.
>>
>> That starts being awfully close to the planck length.
>
> I guess if 15 orders of magnitude is "awfully close"... :-)
>
> I do wonder how big something would have to be for the wavelength to be
> close to the planck length. It would be cool if that was, like, close to
> the size of the observable universe.
>

Not even close, the Earth fit the bill, if I remember corectly.
The Sun would be a few order of magnitude smaller.

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Alain <aze### [at] qwertyorg> wrote:
> Le 2011/09/16 14:23, Warp a écrit :
> > Alain<aze### [at] qwertyorg>  wrote:
> >> For a footbal, it would be in the 10e-20 to 10e-30 m range. So, your
> >> interference pattern would be smaller than a proton.
> >
> >    That starts being awfully close to the planck length.
> >

> We ended up with much smaller values:
> A person, around 10e-50.
> A medium car, around 10e-75.
> The Earth, in the 10e-200 range.

> I don't remember the formula and don't think that I still have it, after 
> over 30 years ;)

  So if the interference pattern of an object the size of a person is
15 orders of magnitude smaller than the planck length, does that mean
that there is no interference pattern, and hence no interference?

-- 
                                                          - Warp

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On 9/16/2011 14:56, Warp wrote:
>    So if the interference pattern of an object the size of a person is
> 15 orders of magnitude smaller than the planck length, does that mean
> that there is no interference pattern, and hence no interference?

Only if a tree in the forest makes a noise if nobody is there to hear it. ;-)

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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On 9/16/2011 14:11, Warp wrote:
>    Now, how does the football (or atom, or particle) "know" that what those
> emitted particles hit is not "measurement"?

Well, that is indeed the fundamental problem exposed by Schrodinger's cat.

> measurement device that can tell the difference?

It doesn't matter if it hits a measuring device. It only matters if you look 
at the measurement.

>    Or is it the *interaction* between the traveling object and the particles
> that hit it (or which it emits), particles that *could* be used to measure
> which slit the object went through, that makes the difference?

No, because you can take the measurement as to which way it went, *then* 
erase that measurement after the particle has already hit the sensor, and 
you will or won't get interference depending on whether you don't or do 
erase the measurement after the fact.

https://secure.wikimedia.org/wikipedia/en/wiki/Quantum_erasure

https://secure.wikimedia.org/wikipedia/en/wiki/Delayed_choice_quantum_eraser

It's not a question of whether it goes thru one slit or two, or whether you 
interfere with it or not at that time. It's (weirdly enough) a question of 
whether you know what the answer was supposed to be.

Remember, tho, that each particle lands in exactly one place. One particle 
doesn't give an interference pattern like one wave would. Each particle in 
the two-slit experiment is just more or less likely to hit different places 
on the screen, but each hits at only one place.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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Darren New <dne### [at] sanrrcom> wrote:
> It doesn't matter if it hits a measuring device. It only matters if you look 
> at the measurement.

  And how does the particle know that the measurement was looked at?

> >    Or is it the *interaction* between the traveling object and the particles
> > that hit it (or which it emits), particles that *could* be used to measure
> > which slit the object went through, that makes the difference?

> No, because you can take the measurement as to which way it went, *then* 
> erase that measurement after the particle has already hit the sensor, and 
> you will or won't get interference depending on whether you don't or do 
> erase the measurement after the fact.

  But that has nothing to do with whether someone "looked" at the measurement
or not. It has to do with whether the two possible paths of the emitted
particle were kept separate or whether they were merged before the particle
hit the measurement device. If I understand correctly, the interference
pattern would disappear if the emitted particles are kept separate even if
nobody "looks" at the result. It has nothing to do with an observer, only
with how the original particles and the emitted particles interact.

  While at macroscopic levels it's hard to understand how particles affect
each other from a significant distance (and even time) this way, it kind of
makes sense, if you imagine that the particles are somehow "bound" together
even though they are in their own separate paths: This way what happens to
one particle affects what happens to the other. If the path of the
"measurement" particle is merged, it affects the original particle (even
through time, via some quantum oddity), and if it's not merged, it also
likewise affects it.

  However, what does not make sense even in this context is that the particle
somehow "knows" whether someone "looked" or not.

-- 
                                                          - Warp

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On 9/16/2011 23:37, Warp wrote:
> Darren New<dne### [at] sanrrcom>  wrote:
>> It doesn't matter if it hits a measuring device. It only matters if you look
>> at the measurement.
>
>    And how does the particle know that the measurement was looked at?

Clearly individual particles don't "know" anything in the traditional sense. 
I suspect if we knew *why* it worked that way, we'd be much closer to a GUT.

>    But that has nothing to do with whether someone "looked" at the measurement
> or not. It has to do with whether the two possible paths of the emitted
> particle were kept separate or whether they were merged before the particle
> hit the measurement device.

You misunderstand. The actual particle hitting the measurement device and 
being checked for interference fringes is *not* the particle being measured. 
*That* particle takes exactly the same path in both cases.

> If I understand correctly, the interference
> pattern would disappear if the emitted particles are kept separate even if
> nobody "looks" at the result. It has nothing to do with an observer, only
> with how the original particles and the emitted particles interact.

I'm not sure what the "emitted" particle is here.

The experiment says basically this:

1) Emit one particle.
2) Run it thru two slits.
3) Split it into an entangled pair, A and B.
4) Let A hit the detector that looks for interference.
5) Some time later, bounce B off a half-silvered mirror,
    such that if it goes through, you can tell what slit it came from,
    and if it doesn't, you can't tell which slit it came from.

The behavior of whether A creates an interference fringe is
determined by whether you can tell which slit B came through. You never need 
to touch A, look at A, or figure out which slit A came through. Two "A" 
photons will cause interference if they weren't in the machine at the same 
time, as long as you don't look at two *other* photons *after* you've 
already determined where the two "A" particles hit the screen. Indeed, you 
could put the detectors for "B" so far from the experiment that thousands of 
"A" particles could have gone through the machine and been detected one at a 
time before you even look at the first "B" particle.

>    While at macroscopic levels it's hard to understand how particles affect
> each other from a significant distance (and even time) this way, it kind of
> makes sense, if you imagine that the particles are somehow "bound" together
> even though they are in their own separate paths: This way what happens to
> one particle affects what happens to the other. If the path of the
> "measurement" particle is merged, it affects the original particle (even
> through time, via some quantum oddity), and if it's not merged, it also
> likewise affects it.

Yes. Except that you can take the second measurement after the first 
particle had already given you an answer. And it works even over time-like 
distances (i.e., if the second detector is so far away that you'd need FTL 
signals for it to affect the first detector), even if you discount the fact 
that it's actually affecting stuff already measured.

>    However, what does not make sense even in this context is that the particle
> somehow "knows" whether someone "looked" or not.

Nope, that doesn't really make sense. :-) Even the multi-worlds 
interpretation of it doesn't make sense, if you actually think about it with 
common sense.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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Darren New <dne### [at] sanrrcom> wrote:
> >    But that has nothing to do with whether someone "looked" at the measurement
> > or not. It has to do with whether the two possible paths of the emitted
> > particle were kept separate or whether they were merged before the particle
> > hit the measurement device.

> You misunderstand. The actual particle hitting the measurement device and 
> being checked for interference fringes is *not* the particle being measured. 
> *That* particle takes exactly the same path in both cases.

  No I don't. When I say "emitted particle" I'm talking about the secondary
particle emitted at the slit towards the measurement device that (possibly)
tells which slit the original particle went through.

> > If I understand correctly, the interference
> > pattern would disappear if the emitted particles are kept separate even if
> > nobody "looks" at the result. It has nothing to do with an observer, only
> > with how the original particles and the emitted particles interact.

> I'm not sure what the "emitted" particle is here.

  It's particle B in your list. If the two possible paths that B could take
are merged, the interference pattern appears, but if they are not merged,
the interference pattern disappears. This regardless of whether someone
"looks" at the result of B or not.

  Clearly what happens to B's path affects A (even if this effect happens
through space and time). It's not dependent on whether someone "looks" at
it.

-- 
                                                          - Warp

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On 9/16/2011 3:07 PM, Darren New wrote:
> On 9/16/2011 14:11, Warp wrote:
>> Now, how does the football (or atom, or particle) "know" that what those
>> emitted particles hit is not "measurement"?
>
> Well, that is indeed the fundamental problem exposed by Schrodinger's cat.
>
>> measurement device that can tell the difference?
>
> It doesn't matter if it hits a measuring device. It only matters if you
> look at the measurement.
>
No, no, no.

Observer in the case of quantum mechanics is not a "person" looking at 
the thing, its "any object/particle that interacts, to take a 
measurement." Whether or not something living looks at the result is 
*not* what produces the effect. Geeze, if that interpretation where 
true, then quantum effects would never have happened *at all* for 
billions of years prior to the formation of life. *Any* interaction 
"measures" the state of the particle *period*. Schrodinger's cat is just 
a goofy anthropomorphizing of the process, which a lot of people, 
including apparently people on here, get wrong, because people see 
"observer" and assume that has to be "person", or something that 
otherwise thinks. That is just plain wrong.

Post a reply to this message

Patrick Elliott <sel### [at] npgcablecom> wrote:
> Schrodinger's cat is just 
> a goofy anthropomorphizing of the process, which a lot of people, 
> including apparently people on here, get wrong, because people see 
> "observer" and assume that has to be "person", or something that 
> otherwise thinks. That is just plain wrong.

  Clearly the cat is a good measurement device for whether the poison was
released or not. That's not the point. The point is whether the cat is
dead or alive from outside of the box.

-- 
                                                          - Warp

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On 9/17/2011 10:13 AM, Warp wrote:
> Patrick Elliott<sel### [at] npgcablecom>  wrote:
>> Schrodinger's cat is just
>> a goofy anthropomorphizing of the process, which a lot of people,
>> including apparently people on here, get wrong, because people see
>> "observer" and assume that has to be "person", or something that
>> otherwise thinks. That is just plain wrong.
>
>    Clearly the cat is a good measurement device for whether the poison was
> released or not. That's not the point. The point is whether the cat is
> dead or alive from outside of the box.
>
Sigh. Outside doesn't matter. The cat is a hypothetical. Just because 
"you" don't know the state, until you open the box, doesn't mean it 
hasn't collapsed, if you are dealing with a literal cat. But that isn't 
what is intended here. The cat is the state itself, in the thought 
experiment, so whether it is one or the other *requires* an outside 
influence. A real cat would already invalidate the experiment, as would 
anything else you might use, like a sheet of radiation sensitive 
material, where you want to "observe" if the material decayed yet, or 
not. It happens, in such cases, whether you open the box now, or 4 
million years from now. That you don't know what happened isn't relevant.

But, if you are talking about the cat as a "state", and the observation 
as checking to see if the state changed, the situation is, in principle, 
valid. But, you have to make everything hypothetical to have it mean 
anything. Did the laser fire (the poison release)? Did it emit a 
particle in the right direction (no leaks in the box)? Did that particle 
split as intended (the cat breathed it, maybe it was a really short 
lived poison)? When it did, what happened to the pair you are testing 
(was the cat effected)? The cat is just one of the cogs in the system. 
Assuming event #1 happened, as planned, something happens in the rest of 
the system, whether you did anything yourself or not. The *real* trick 
is the fact that you can create conditions where you "know" what the 
outcome will be, instead of just looking into the box to find out. 
Normally, you can't, because all the stuff going on happens "in the box".

Post a reply to this message

On 9/17/2011 9:44, Warp wrote:
> Darren New<dne### [at] sanrrcom>  wrote:
>>>     But that has nothing to do with whether someone "looked" at the m
easurement
>>> or not. It has to do with whether the two possible paths of the emitt
ed
>>> particle were kept separate or whether they were merged before the pa
rticle
>>> hit the measurement device.
>
>> You misunderstand. The actual particle hitting the measurement device 
and
>> being checked for interference fringes is *not* the particle being mea
sured.
>> *That* particle takes exactly the same path in both cases.
>
>    No I don't. When I say "emitted particle" I'm talking about the seco
ndary
> particle emitted at the slit towards the measurement device that (possi
bly)
> tells which slit the original particle went through.

Ah. With that clarification in mind... The interference pattern disappear
s 
if you don't actually look at the "emitted" particle at all. If you let t
he 
emitted particle hit the detector, then you don't use that detector's 
results, you get no interference pattern - you get just a level output. 
That's what this paragraph means:

"""
Note that the total pattern of all signal photons at D0, whose entangled 

idlers went to multiple different detectors, will never show interference
 
regardless of what happens to the idler photons.[3] One can get an idea o
f 
how this works by looking carefully at both the graph of the subset of 
signal photons whose idlers went to detector D1 (fig. 3 in the paper[1]) 
and 
the graph of the subset of signal photons whose idlers went to detector D
2 
(fig. 4), and observing that the peaks of the first interference pattern 

line up with the troughs of the second and vice versa (noted in the paper
 as 
'a π phase shift between the two interference fringes'), so that the
 sum of 
the two will not show interference.
"""

In this particular experimental setup, if you don't look at which detecto
r 
it hit, you can't tell because you can't separate out the inteference fro
m 
it's half-phase-shifted brother.

>>> If I understand correctly, the interference
>>> pattern would disappear if the emitted particles are kept separate ev
en if
>>> nobody "looks" at the result. It has nothing to do with an observer, 
only
>>> with how the original particles and the emitted particles interact.
>
>> I'm not sure what the "emitted" particle is here.
>
>    It's particle B in your list. If the two possible paths that B could
 take
> are merged, the interference pattern appears, but if they are not merge
d,
> the interference pattern disappears. This regardless of whether someone

> "looks" at the result of B or not.

In this experiment at least, you *have* to look at B in order to determin
e 
which category A falls into. If you don't look at B at all, you don't get
 
interference fringes, or more precisely, you get two sets of interference
 
fringes that are half a fringe offset.

>    Clearly what happens to B's path affects A (even if this effect happ
ens
> through space and time). It's not dependent on whether someone "looks" 
at
> it.

In this case, not *quite*, I think. (Again, you're skirting the edges of 
my 
understanding... :-)  There have been other experiments proposed (by 
Wheeler, for example) that don't involve a second entangled photon at all
, 
but are hard to set up because you need devices that are light-seconds lo
ng 
to make them work. :-)

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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On 9/17/2011 9:58, Patrick Elliott wrote:
> Observer in the case of quantum mechanics is not a "person" looking at the
> thing, its "any object/particle that interacts, to take a measurement."

Nope.  Contradicted by experimental evidence. Go read the other branch of 
the thread, and read the quantum erasure articles.

> Whether or not something living looks at the result is *not* what produces
> the effect. Geeze, if that interpretation where true, then quantum effects
> would never have happened *at all* for billions of years prior to the
> formation of life.

No, quantum *collapse* wouldn't have happened. :-)

> *Any* interaction "measures" the state of the particle
> *period*.

Again, this is contradicted by experimental evidence.

Unless you have something else to point to, that shows where an experiment 
where the scientists took a measurement but then didn't look at it still 
caused the collapse?

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

Post a reply to this message

On 9/18/2011 1:02, Patrick Elliott wrote:
> The *real* trick is the fact that you can create conditions
> where you "know" what the outcome will be, instead of just looking into the
> box to find out.

That's exactly what the quantum eraser does, and if you don't look at the 
result, you don't get interference. That's precisely the point I'm making. 
You get interference at time T by taking a measurement at time T+D, where D 
is a timelike separation from T.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

Post a reply to this message

Darren New <dne### [at] sanrrcom> wrote:
> In this case, not *quite*, I think. (Again, you're skirting the edges of my 
> understanding... :-)  There have been other experiments proposed (by 
> Wheeler, for example) that don't involve a second entangled photon at all, 
> but are hard to set up because you need devices that are light-seconds long 
> to make them work. :-)

  Btw, I don't understand why the double slit experiment cannot be used to
send information faster than c.

  Suppose you set up the delayed-choice experiment on orbit around Alpha
Centauri such that you simply shoot a beam of light towards the slits,
behind which there's a detector surface which can be used to see if there's
an interference pattern or not. Then you put the photon splitters at the
slits and send the secondary light particles created this way towards Earth.

  On earth we receive these two secondary beams, and here we make a delayed
choice of whether to merge them or not before measurement. If we merge them,
then the interference pattern appears at Alpha Centauri, and if we don't
merge them (but measure which slit the photons went through) the interference
pattern disappears. This way we can send binary data from Earth to Alpha
centauri: To send a 0 we eg. merge the paths, and to send a 1 we don't.
The guys at Alpha Centauri can then read this info by seeing when the
interference pattern appears and when it doesn't.

  Since the particles are entangled, this happens without any delay.
(The secondary beams my take 4 light years to arrive here, but once they
do, we can send data back immediately, without another 4 ly delay. If the
streams are kept constantly on, after the initial 4 ly delay information
can be send continuously from Earth to Alpha Centauri with zero delay.)

  But apparently this is not possible. Why not?

-- 
                                                          - Warp

Post a reply to this message

On 9/18/2011 9:37, Warp wrote:
>    On earth we receive these two secondary beams, and here we make a delayed
> choice of whether to merge them or not before measurement. If we merge them,
> then the interference pattern appears at Alpha Centauri, and if we don't
> merge them (but measure which slit the photons went through) the interference
> pattern disappears.

Except you can't tell, in the case of this specific experiment, which 
electrons are part of the interference pattern and which electrons are part 
of the non-interference pattern until after you've detected the "B" idler 
photons. You're going to get all the photons, and what you have to do to get 
the interference pattern is to ignore the photons where I erased the 
information about my half of the experiment. Remember that you don't get an 
interference pattern from just one particle. You get an interference pattern 
statistically, when you let lots of particles build up. There's no way to 
look at one individual particle and say "is that part of an interference 
pattern?"

The way the particular experiment on the wiki page is described, 1/4th the 
particles randomly create an interference pattern, 1/4th randomly create an 
interference pattern offset 1/2 a fringe from the first one, and 1/2 of the 
particles create no interference pattern. But you don't know which group 
each particle is in until you look at the idler "B" emitted photon to see 
which way it went.  If you *influence* the emitted particle, you break the 
entanglement, and now you have results uncorrelated with the emitted 
particle, which (I think) means you'll get an interference fringe from the 
"A" particles because you erased what would let you distinguish them.



It's the same as a simpler question: Why can't I send any information at all 
over a quantum channel? Any experiment you concoct to measure a quantum 
property one way or the other to communicate is going to run up against the 
fact that the property you're measuring is influenced by the property you 
aren't measuring.

Let's say I decide to measure polarization, diagonal for 1, 
horizontal/vertical for 0. I send you half an entangled stream, then measure 
diagonal polarization or H/V polarization for each bit. The problem is that 
if you measure the H/V polarization when I measure the diagonal 
polarization, you just get random nonsense. You already have to know which 
polarization I'm going to measure in order to measure the same polarization. 
And if we both measure the same polarization, we'll get the same answers, 
but the answers will be a random stream of bits.




Or, for a super-simple analogy, let's say I have a glass table. You can see 
the underside of the glass table instantly, no matter where you are. So you 
go far away, and I stand next to the glass table. However, the only thing 
you can see through the glass of the table is a coin I have flipped.

So if I flip a coin and it lands heads up, I know instantly that you 
instantly saw the tails side of the coin. If it lands tails up, I know 
instantly that you know instantly that it landed heads up. That's FTL.

Now, what can we do with that data? Not much. It's a random stream of bits 
over which I have no control. If I set the coin down in a specific way, you 
can't see it. I know you saw the compliment of what I saw, but I have no way 
to influence that. If I try to influence it, the whole process collapses and 
you can no longer see the results from far away.




That's why, if you look at quantum cryptography, the quantum part of the 
process is used to generate a OTP, then to ensure the OTP hasn't been 
intercepted by someone else. But the actual communication, including the 
part where you ensure the OTP hasn't been intercepted, happens over normal 
non-quantum channels.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

Post a reply to this message

Am 18.09.2011 18:27, schrieb Darren New:
> On 9/18/2011 1:02, Patrick Elliott wrote:
>> The *real* trick is the fact that you can create conditions
>> where you "know" what the outcome will be, instead of just looking
>> into the
>> box to find out.
>
> That's exactly what the quantum eraser does, and if you don't look at
> the result, you don't get interference. That's precisely the point I'm
> making. You get interference at time T by taking a measurement at time
> T+D, where D is a timelike separation from T.

Something's wrong there, because it would allow me to define a protocol 
to transfer information back in time:

- At time T+D, I decide wheter I take a measurement or not depending on 
some information.

- At time T, I check whether I get interference or not, which tells me 
whether I'll be measuring at T+D, which in turn gives me the desired 
information.

Last not least, I could even base my decision whether to take a 
measurement or not on whether I get interference or not - which would 
obviously cause a problem with causality.

Post a reply to this message

On 9/18/2011 9:27 AM, Darren New wrote:
> On 9/18/2011 1:02, Patrick Elliott wrote:
>> The *real* trick is the fact that you can create conditions
>> where you "know" what the outcome will be, instead of just looking
>> into the
>> box to find out.
>
> That's exactly what the quantum eraser does, and if you don't look at
> the result, you don't get interference. That's precisely the point I'm
> making. You get interference at time T by taking a measurement at time
> T+D, where D is a timelike separation from T.
>
Well.. Yes and no. The quantum eraser "changes the conditions" withing 
that D time frame, such that the transition to a state is interrupted, 
by inserting a new set of conditions that allow for the prior quantum 
state. Since the transition never took place, no state change happened. 
Basically, it is the equivalent of deciding, at the last possible 
instant, to not open the hypothetical box, to look inside. That you 
rigged the box lid, before hand, such that the result "must" be what you 
wanted, doesn't change the fact that you never really opened it, so your 
"rigged" conditions never came into play (or, rather, in this case, you 
jiggled the poison container, but didn't break it).

Post a reply to this message

On 9/18/2011 9:25 AM, Darren New wrote:
> Again, this is contradicted by experimental evidence.
>
> Unless you have something else to point to, that shows where an
> experiment where the scientists took a measurement but then didn't look
> at it still caused the collapse?
>
:head desk: ?? This is nonsense. You can't take a measurement without 
causing a collapse *period*. Try talking to an actually physicist about 
that, and not Depok Chopra. Measurement, by definition, means that your 
test particle had to have an effect on another particle. It is not 
possible to do that, without both particles affecting *each other*, thus 
triggering the collapse. The measurement *is* the observation, and the 
test equipment *is* the observer. That some other later on read a 
computer screen, and went, "Yup, the particle hit the detector.", is 
irrelevant to the result. It was already "observed" by the measuring device.

Or, do you have some magical way to "measure" this stuff, which somehow 
doesn't involve particle collisions?

Post a reply to this message

On 9/18/2011 15:31, Patrick Elliott wrote:
> Well.. Yes and no. The quantum eraser "changes the conditions" withing that
> D time frame, such that the transition to a state is interrupted, by
> inserting a new set of conditions that allow for the prior quantum state.

Right.

> Since the transition never took place, no state change happened.

Right. Indeed, that's the point of the experiment.  That it is *not* the 
case that the particle went through one slit or the other or both.

You said
 > A real cat would already invalidate the experiment, as would anything 
else you might use, like a sheet of radiation sensitive material

But that's clearly not the case, if what you're measuring is whether the 
particle went through one slit or the other or both or neither.

Other than that, you're pushing the analogy too far for me to track what 
you're talking about.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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On 9/18/2011 15:38, Patrick Elliott wrote:
> Measurement, by definition, means that your test
> particle had to have an effect on another particle.

No. That's the entire point of using an entangled particle. The particle 
you're checking for interference is never touched by the rest of the experiment.

> It is not possible to do
> that, without both particles affecting *each other*, thus triggering the
> collapse.

Yes. And that's the funky part, now isn't it?  I'm not sure why you first 
bang your head on the desk, then agree with me.

> The measurement *is* the observation, and the test equipment *is*
> the observer. That some other later on read a computer screen, and went,
> "Yup, the particle hit the detector.", is irrelevant to the result. It was
> already "observed" by the measuring device.

Yes, in this case.  Again, I'm not sure why you seem to be disagreeing with me.

> Or, do you have some magical way to "measure" this stuff, which somehow
> doesn't involve particle collisions?

Yes. You split the particle into an entangled pair via spontaneous 
down-conversion, then you interact with only one of the pair. Indeed, that's 
the whole point of the experiment: you're *not* interacting with the 
particle whose behavior changes based on whether you interact with the other 
particle. Hence, it is nonsensical to say "the particle knows what slit it 
went through" or something like that.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

Post a reply to this message

On 9/18/2011 4:32 PM, Darren New wrote:
> On 9/18/2011 15:31, Patrick Elliott wrote:
>> Well.. Yes and no. The quantum eraser "changes the conditions" withing
>> that
>> D time frame, such that the transition to a state is interrupted, by
>> inserting a new set of conditions that allow for the prior quantum state.
>
> Right.
>
>> Since the transition never took place, no state change happened.
>
> Right. Indeed, that's the point of the experiment. That it is *not* the
> case that the particle went through one slit or the other or both.
>
> You said
>  > A real cat would already invalidate the experiment, as would anything
> else you might use, like a sheet of radiation sensitive material
>
> But that's clearly not the case, if what you're measuring is whether the
> particle went through one slit or the other or both or neither.
>
> Other than that, you're pushing the analogy too far for me to track what
> you're talking about.
>
What I am saying is that, in the case of the quantum eraser, you are 
rigging things so that the event doesn't happen, or a different one 
does. I think the confusion here is where the "observation" takes place, 
and where the measurement does. In this case you have sort of decoupled 
them. You are creating an "observer", which is affected by the particle, 
and in turn begins collapsing its state, then you introduce a new 
"observer", which either erases the result, or changes it to something 
else, then you "measure" what happened as a result. The term "observer" 
becomes more ambiguous in this case. A proper term would have been 
"interactor", i.e., the thing that alters the state. The confusion 
arises in that a) that isn't really a word, and b) they opted for the 
misleading term "observer", when talking about how the state collapses. 
In reality, the measurement doesn't have to happen when the first 
observation takes place. It may not even be possible to measure that 
interaction at all, save as a consequence of it having happened. Q.E.D. 
Whether you measure the system or not, doesn't effect if something 
happened, since measurement and interaction/observation are rarely 
simultaneous, in *any* experiment, nor is the act of measuring critical 
to the result.

Post a reply to this message

On 9/18/2011 4:36 PM, Darren New wrote:
>> It is not possible to do
>> that, without both particles affecting *each other*, thus triggering the
>> collapse.
>
> Yes. And that's the funky part, now isn't it? I'm not sure why you first
> bang your head on the desk, then agree with me.

Not the entangled particles, I mean what ever "particle" in the device 
you are using the trigger the effect desired, and which ever one of the 
the entangled pair you are playing with, to produce that result. You 
don't get an effect in a vacuum (well, you do, but the odds of a 
collisions are a lot damn less likely lol), you have to have the 
particle pair you are testing with "interact" with something. That 
interaction, as I said in the other post, is almost never, if ever, the 
measuring device. So, measurement is irrelevant to the problem.

Post a reply to this message

On 9/19/2011 17:02, Patrick Elliott wrote:
> What I am saying is that, in the case of the quantum eraser, you are rigging
> things so that the event doesn't happen, or a different one does.

Right. Indeed, that's the point.

> the confusion here is where the "observation" takes place, and where the
> measurement does.

In a system where the measurement device isn't performed by a living 
organism (i.e., most anything except the cat thought experiment) I don't 
think it's useful to decouple those terms.

> the thing that alters the state.

And in the case of the quantum delayed choice eraser, what is "the thing" 
that alters "the state"?

> b) they opted for the misleading term "observer", when
> talking about how the state collapses.

That's the problem. Nobody could come up with a reason that the state would 
collapse at all. I'm not sure even now it's a solved problem.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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On 9/19/2011 17:06, Patrick Elliott wrote:
> you have to have the particle pair you are testing
> with "interact" with something. That interaction, as I said in the other
> post, is almost never, if ever, the measuring device.

I don't understand how you decouple the two. You shoot a photon at a 
photomultiplier. The photomultiplier emits a click. The interaction causes 
the measurement. I don't know how you take a measurement without an 
interaction of *some* sort, and I don't know how you interact with something 
without taking a measurement unless you entangle your state with the device 
with which you're interacting.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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On 9/19/2011 6:11 PM, Darren New wrote:
>> the thing that alters the state.
>
> And in the case of the quantum delayed choice eraser, what is "the
> thing" that alters "the state"?
>
If what you are doing is "undoing" the stat change, then its still the 
same thing as would have changed the state, uh.. sort of.. Yeah, 
confusing, but its not quite so big of a problem as it first appears. 
Something is still "effecting" the state, even if the "effect" is to 
prevent a transition into one that is collapsed.

>> b) they opted for the misleading term "observer", when
>> talking about how the state collapses.
>
> That's the problem. Nobody could come up with a reason that the state
> would collapse at all. I'm not sure even now it's a solved problem.
>
I tend to think that they are either confusing themselves. There is no 
reason it wouldn't. But, we think about things with language. So, if you 
are using the wrong bloody language, it creates all sorts of errors in 
thinking.

In principle, as long as a particle is isolated from influences that 
"can" collapse the state, it won't. But, its an unstable arrangement, 
and you can't even be certain to maintain it in a vacuum, given some 
small odds that a virtual particle will happen to pop in and mess with 
things. In a practical sense, it simply means that, if you don't alter 
its unstable state, then it will change state when it hits something 
else, just not what ever it was you where intended to "measure" it with. 
After all, in this case, you are dealing with a photon, and your 
"detector" is only in one very small area. If the thing hits something 
where you can't see it, it still hits something, eventually, and.. 
without state collapses, the world would be awfully full of random 
photons, which happened, by chance, to split, forming entangled pairs, 
and yet where never "observed" in the sense described.

Personally, I consider the confusion over what happens if you don't 
"see" it happen to be complete nonsense, like arguing that noise doesn't 
happen if a tree falls without a observer, yet discounting that the 
impact, and subsequent vibrations, still do. The distinction is absurd, 
even if technically correct.

Post a reply to this message

On 9/19/2011 6:13 PM, Darren New wrote:
> On 9/19/2011 17:06, Patrick Elliott wrote:
>> you have to have the particle pair you are testing
>> with "interact" with something. That interaction, as I said in the other
>> post, is almost never, if ever, the measuring device.
>
> I don't understand how you decouple the two. You shoot a photon at a
> photomultiplier. The photomultiplier emits a click. The interaction
> causes the measurement. I don't know how you take a measurement without
> an interaction of *some* sort, and I don't know how you interact with
> something without taking a measurement unless you entangle your state
> with the device with which you're interacting.
>
In this case, yes. But you are forgetting the "other" condition of the 
test, i.e., placing something into the path of one of the entangled 
particles, thus causing it to change state, thus resulting in it never 
"being" detected. The point being, the state changes, regardless of 
whether your "detector" is the thing that changed it, or something else 
did. Thus, they are decoupled, in the sense that the detector, and thus 
observation, is not needed to collapse the state. Its merely incidental 
that, when you allow the detector to be the state changer, it both 
"changes" the state, and "measures" the result.

Post a reply to this message

On 9/20/2011 16:54, Patrick Elliott wrote:
> On 9/19/2011 6:11 PM, Darren New wrote:
>>> the thing that alters the state.
>>
>> And in the case of the quantum delayed choice eraser, what is "the
>> thing" that alters "the state"?
>>
> If what you are doing is "undoing" the stat change, then its still the same
> thing as would have changed the state, uh.. sort of.. Yeah, confusing, but
> its not quite so big of a problem as it first appears. Something is still
> "effecting" the state, even if the "effect" is to prevent a transition into
> one that is collapsed.

Well, yes, but that's just explaining the results of the experiment without 
actually shedding any additional light on why it behaves that way.


>>> b) they opted for the misleading term "observer", when
>>> talking about how the state collapses.
>>
>> That's the problem. Nobody could come up with a reason that the state
>> would collapse at all. I'm not sure even now it's a solved problem.
>>
> I tend to think that they are either confusing themselves. There is no
> reason it wouldn't.

Oh? So you've solved the problem? Do tell, why does the quantum state 
collapse instead of merely becoming entangled with whatever it interacts with?

> But, we think about things with language. So, if you are
> using the wrong bloody language, it creates all sorts of errors in thinking.

I'm pretty sure the people who ague about this for real aren't using prose 
to do so.

> In principle, as long as a particle is isolated from influences that "can"
> collapse the state, it won't.

Why does a particle bouncing off a mirror not collapse the state? Certainly 
there's interaction there. Indeed, where in the wave equations is the 
expression for the collapse of the state? That's really pretty much what the 
question boils down to.

> Personally, I consider the confusion over what happens if you don't "see" it
> happen to be complete nonsense,

Except you get different experimental results depending on whether you see 
it or not. That indeed is the entire point.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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On 9/20/2011 16:57, Patrick Elliott wrote:
> In this case, yes. But you are forgetting the "other" condition of the test,
> i.e., placing something into the path of one of the entangled particles,
> thus causing it to change state, thus resulting in it never "being"
> detected.

Both particles are detected. If you miss one particle or the other, the 
sample gets thrown away. I'm not sure what "being" detected means, other 
than that.

> The point being, the state changes, regardless of whether your
> "detector" is the thing that changed it, or something else did.

Right. And the problem is that the state apparently changes when *nothing* 
interacts with the particle. What causes that state change?

> Thus, they
> are decoupled, in the sense that the detector, and thus observation, is not
> needed to collapse the state.

It's not needed, but in this experiment, it is indeed what causes the 
collapse. I'm not sure what you're trying to say.

> Its merely incidental that, when you allow the
> detector to be the state changer, it both "changes" the state, and
> "measures" the result.

No. The detector measures the result. Sometimes it changes it, sometimes it 
doesn't. And when the second detector changes the result, the first detector 
winds up having a different result also. That's the point of the experiment. 
I'm not sure how you're waving that off with "well, of course, but it has 
nothing to do with the measurements."

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

Post a reply to this message

On 9/21/2011 8:34 AM, Darren New wrote:
> Why does a particle bouncing off a mirror not collapse the state?
> Certainly there's interaction there. Indeed, where in the wave equations
> is the expression for the collapse of the state? That's really pretty
> much what the question boils down to.
>
Yeah, that is kind of an interesting case. The question is what sort of 
interaction are you dealing with, with respect to a mirror, that isn't 
the same as if it hits something that doesn't have reflection? The only 
answer I have is that this is who mirrors work, for some reason, in that 
they "deflect" a particle, without causing a change. No idea why. But, 
if they didn't, we wouldn't have mirrors, pretty much by definition.

>> Personally, I consider the confusion over what happens if you don't
>> "see" it
>> happen to be complete nonsense,
>
> Except you get different experimental results depending on whether you
> see it or not. That indeed is the entire point.
>

But, its not. What is the fundamental difference between these 
categories of experiment design:

1. Two detectors, one farther away than the other, where you expect the 
first one to detect the entangled particle, but the farther one to not.

2. One detector, and one solid block, where the block is closer, again, 
with the expectation that you will get no result, since the entangled 
pair "stops" at the block, and never reaches the detector.

3. No detectors, but blocks in the same positions as above.

You are proposing that "somehow" #3 is completely different, and that 
only #1, and maybe #2, somehow, produce a predictable effect. I say this 
is absurd. Where exactly does the entangled second particle go, if it 
doesn't collapse into its twin, in case #3? What ever relevance to a 
mirrors ability to deflect a particle, without causing a collapse, is 
not relevant to this question. You could build your system without "any" 
mirrors, and you still have the same bloody situation. So, the question 
is, I think, fundamentally wrong. Its not, "Why does observation appear 
necessary?", but rather, "What exactly is it in the nature of mirrors 
that produces a different result than a non-reflective object?" I don't 
see how assuming that the first question makes any sort of sense leads 
you to finding any sort of answer to the second one.

Oh, and its not about "prose". Language is critical to how we think. A 
great many things we failed to grasp in the past *precisely* because the 
language was inadequate to describe them, and new language had to be 
defined, before comprehension was possible. The words we use "color" our 
perceptions, and determine how, and even if, in some cases, we can 
examine a problem. I seem to even remember studies on this, though I 
can't think of exactly when, or where, I read about it.

Post a reply to this message

On 9/21/2011 8:37 AM, Darren New wrote:
> On 9/20/2011 16:57, Patrick Elliott wrote:
>> In this case, yes. But you are forgetting the "other" condition of the
>> test,
>> i.e., placing something into the path of one of the entangled particles,
>> thus causing it to change state, thus resulting in it never "being"
>> detected.
>
> Both particles are detected. If you miss one particle or the other, the
> sample gets thrown away. I'm not sure what "being" detected means, other
> than that.
>
>> The point being, the state changes, regardless of whether your
>> "detector" is the thing that changed it, or something else did.
>
> Right. And the problem is that the state apparently changes when
> *nothing* interacts with the particle. What causes that state change?
>
An unnoticed speck of dust, or in a vacuum, a virtual particle? How 
exactly are they isolating things to "prevent" any interactions?

>> Thus, they
>> are decoupled, in the sense that the detector, and thus observation,
>> is not
>> needed to collapse the state.
>
> It's not needed, but in this experiment, it is indeed what causes the
> collapse. I'm not sure what you're trying to say.
>
>> Its merely incidental that, when you allow the
>> detector to be the state changer, it both "changes" the state, and
>> "measures" the result.
>
> No. The detector measures the result. Sometimes it changes it, sometimes
> it doesn't. And when the second detector changes the result, the first
> detector winds up having a different result also. That's the point of
> the experiment. I'm not sure how you're waving that off with "well, of
> course, but it has nothing to do with the measurements."
>
You know, I get the distinct feeling that, at least at some level, we 
are talking past each other. Then you come up with non-sequitors, like 
the idea that the effect of one detector, which I assume is not equal 
distant, can either cause, or not, a change in the other. Yet, somehow, 
I don't think that is what you are saying. What you seem to be saying is 
that an imperfect surface might coincidentally be hit in both detectors 
at the close enough to the same moment, to cause an "unchanged" state, 
i.e., both detect that state, while in other case, the interaction with 
one detector just happens to fall within the bounds of the time that it 
takes to transition, resulting in one detector "causing" a state change, 
with the other detecting the same.

Unless you are suggesting that, somehow, they are making one particle 
thick detectors, with perfect properties, and an "absolutely" smooth 
surface? Seems to em to be much more plausible that this ambiguity is a 
consequence of the imperfect nature of the detectors, not something 
profoundly strange going on. But, hell, what do I know...

Post a reply to this message

On 9/21/2011 12:05, Patrick Elliott wrote:
> Yeah, that is kind of an interesting case. The question is what sort of
> interaction are you dealing with, with respect to a mirror, that isn't the
> same as if it hits something that doesn't have reflection?

Except the interactions with mirrors are the same as the interactions with 
the other stuff. There's only one wave equation.

I don't know the answer, but I'm not trying argue that the answer is simple 
and obvious, either.

>> Except you get different experimental results depending on whether you
>> see it or not. That indeed is the entire point.
>>
>
> But, its not. What is the fundamental difference between these categories of
> experiment design:
>
> 1. Two detectors, one farther away than the other, where you expect the
> first one to detect the entangled particle, but the farther one to not.
>
> 2. One detector, and one solid block, where the block is closer, again, with
> the expectation that you will get no result, since the entangled pair
> "stops" at the block, and never reaches the detector.
>
> 3. No detectors, but blocks in the same positions as above.
>
> You are proposing that "somehow" #3 is completely different, and that only
> #1, and maybe #2, somehow, produce a predictable effect.

Uh, no. This is nonsense. I'm proposing no such thing. What did I say that 
lead you to believe that?

> Where exactly does the entangled second particle go, if it doesn't
> collapse into its twin, in case #3?

In all three cases, the entagled particles stop at either the detector or 
the block, depending on what's in their way. Why would you think otherwise? 
You realize that in every case there are two particles, yes? And an 
"entangled" particle needs to be entangled with some other particle, 
implying the existence of two particles?

I haven't any idea where you're coming from here.

> Oh, and its not about "prose". Language is critical to how we think. A great
> many things we failed to grasp in the past *precisely* because the language
> was inadequate to describe them, and new language had to be defined, before
> comprehension was possible. The words we use "color" our perceptions, and
> determine how, and even if, in some cases, we can examine a problem. I seem
> to even remember studies on this, though I can't think of exactly when, or
> where, I read about it.

Of course. I'm just pointing out that the people who describe entanglement 
don't talk about cats. They have mathematics that describe it.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

Post a reply to this message

On 9/21/2011 12:15, Patrick Elliott wrote:
> An unnoticed speck of dust, or in a vacuum, a virtual particle? How exactly
> are they isolating things to "prevent" any interactions?

If the photon was colliding with a speck of dust, you wouldn't see it, and 
you wouldn't get a coincident detection. Ipso facto columbo oreo.

> You know, I get the distinct feeling that, at least at some level, we are
> talking past each other. Then you come up with non-sequitors, like the idea
> that the effect of one detector, which I assume is not equal distant, can
> either cause, or not, a change in the other. Yet, somehow, I don't think
> that is what you are saying.

No, that's exactly what I'm saying. And exactly what the wikipedia article I 
pointed ot is saying.

 > What you seem to be saying is that an imperfect
> surface might coincidentally be hit in both detectors at the close enough to
> the same moment, to cause an "unchanged" state, i.e., both detect that
> state, while in other case, the interaction with one detector just happens
> to fall within the bounds of the time that it takes to transition, resulting
> in one detector "causing" a state change, with the other detecting the same.

Did you even read the quantum delayed erasure wikipedia article? Did you 
understand what it says? If not, that would certainly explain the confusion.

> Unless you are suggesting that, somehow, they are making one particle thick
> detectors, with perfect properties, and an "absolutely" smooth surface?
> Seems to em to be much more plausible that this ambiguity is a consequence
> of the imperfect nature of the detectors, not something profoundly strange
> going on. But, hell, what do I know...

Well, I don't know what to say. They do an experiment, it shows what you'd 
expect from the wave equations, even tho that's profoundly strange. And you 
seem to be arguing that they're doing ... some other experiment, because the 
one they're doing would be too strange or something.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

Post a reply to this message

On 9/22/2011 8:31 AM, Darren New wrote:
> On 9/21/2011 12:05, Patrick Elliott wrote:
>> Yeah, that is kind of an interesting case. The question is what sort of
>> interaction are you dealing with, with respect to a mirror, that isn't
>> the
>> same as if it hits something that doesn't have reflection?
>
> Except the interactions with mirrors are the same as the interactions
> with the other stuff. There's only one wave equation.
>
> I don't know the answer, but I'm not trying argue that the answer is
> simple and obvious, either.
>
Might be as simple as, "This is a special case where the wave equation 
is not the one you should be using." In general, the solution is almost 
also something simple. One possible "simple" solution, though it would 
create its own insane questions, would be that a mirror doesn't "bend" 
light, but actually emits a new particle, and does so in a way that 
"causes" the entanglement to remain, either by causing the first one to 
collapse, and a new entangled particle to show up, moving in the new 
direction, or by somehow trading off the new and old one, with the other 
half of the pair. It would certainly mess with the existing rules of 
what is assumed to happen, but not directly violate the wave equations. 
It would also be damn hard to detect/test, since.. how do you tell one 
particle from another, if their wavelength, and other characteristics, 
save for direction of travel, where all identical?

>>> Except you get different experimental results depending on whether you
>>> see it or not. That indeed is the entire point.
>>>
>>
>> But, its not. What is the fundamental difference between these
>> categories of
>> experiment design:
>>
>> 1. Two detectors, one farther away than the other, where you expect the
>> first one to detect the entangled particle, but the farther one to not.
>>
>> 2. One detector, and one solid block, where the block is closer,
>> again, with
>> the expectation that you will get no result, since the entangled pair
>> "stops" at the block, and never reaches the detector.
>>
>> 3. No detectors, but blocks in the same positions as above.
>>
>> You are proposing that "somehow" #3 is completely different, and that
>> only
>> #1, and maybe #2, somehow, produce a predictable effect.
>
> Uh, no. This is nonsense. I'm proposing no such thing. What did I say
> that lead you to believe that?
>
>> Where exactly does the entangled second particle go, if it doesn't
>> collapse into its twin, in case #3?
>
> In all three cases, the entagled particles stop at either the detector
> or the block, depending on what's in their way. Why would you think
> otherwise? You realize that in every case there are two particles, yes?
> And an "entangled" particle needs to be entangled with some other
> particle, implying the existence of two particles?
>
> I haven't any idea where you're coming from here.
>
The phrasing of your "prior" statement was to the effect that, "This 
doesn't happen unless you are observing it." That was what was seriously 
making me wonder. How to you observe the "absence" of a particle, which 
is what happens when your detector is the more distant thing? That makes 
no logical sense, and if its not what you meant, then you mistyped. Its 
the issue I have been trying to resolve since you made the statement.

Post a reply to this message

On 9/22/2011 8:34 AM, Darren New wrote:
>  > What you seem to be saying is that an imperfect
>> surface might coincidentally be hit in both detectors at the close
>> enough to
>> the same moment, to cause an "unchanged" state, i.e., both detect that
>> state, while in other case, the interaction with one detector just
>> happens
>> to fall within the bounds of the time that it takes to transition,
>> resulting
>> in one detector "causing" a state change, with the other detecting the
>> same.
>
> Did you even read the quantum delayed erasure wikipedia article? Did you
> understand what it says? If not, that would certainly explain the
> confusion.
>
No, the confusion was in what you seemed to state was going on. Not what 
the article said. I don't think I intentionally misread you, but what 
you wrote implied something else entirely, or at least seemed to.

Post a reply to this message

On 9/22/2011 11:18, Patrick Elliott wrote:
> Might be as simple as, "This is a special case where the wave equation is
> not the one you should be using."

There's really only one, you know. At least for photons vs electrons.

> One possible "simple" solution, though it would create its
> own insane questions, would be that a mirror doesn't "bend" light, but
> actually emits a new particle,

Um, we already know that's the case.

> would certainly mess with the existing rules of what is assumed to happen,
> but not directly violate the wave equations. It would also be damn hard to
> detect/test, since.. how do you tell one particle from another, if their
> wavelength, and other characteristics, save for direction of travel, where
> all identical?

You test it by reflecting the light off a surface that also lets some of the 
light pass through, like glass, and studying the interference patterns.

> The phrasing of your "prior" statement was to the effect that, "This doesn't
> happen unless you are observing it." That was what was seriously making me
> wonder. How to you observe the "absence" of a particle, which is what
> happens when your detector is the more distant thing?

I don't know what particle you think is absent. You don't get interference 
effects unless you observe the entangled particle. You're not observing the 
absence of anything. I never meant to imply any particle was missing. I was 
talking about the wikipedia page. If you want to keep talking about this, 
talk about the wikipedia page, and not what you think I might have been 
saying about it.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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