Apparently objective quantum wave function collapse doesn't occur

[John Clark]

One of the main competitors to Everett's Many Worlds idea is Continuous Spontaneous Localization, the idea that an additional term needs to be added to Schrödinger's wave equation that randomly and very rarely collapses the wave function so there is only one objective reality. One great advantage of this idea is that it can be tested empirically, the experiment needed is conceptually simple but requires great skill to actually perform, but it has been done in the last few months and the results are negative, there is no sign of spontaneous quantum wave function collapse. For the idea to work now its advocates would have to add yet more mathematical bells and whistles to their new equation which is already very complicated and downright baroque, and that's always a bad sign. Many Worlds is looking better than ever.

Search for Spontaneous Radiation from Wave Function Collapse in the Majorana Demonstrator

John K Clark

[spudb...@aol.com]

In another world, some bright mathematician has already come up with the proper diophantine equations to render MWI a non-starter.

In this one, we still hold the actions predicted by Everett, DeWitt, & Wheeler to be true. 

Above it all, Strong, on their Holographic Mountain, Hugh Everett the 3rd, and Crom, laughs and heaps ridicule upon our puny intellects!

Here we sit, entangled up in blue. 

'Spooky action at a distance' can lead to a multiverse.

'Spooky action at a distance' can lead to a multiverse. Here's how. (msn.com)

We shall soon see if there are other analogs for coffee in other spacetimes? 

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[Lawrence Crowell]

The dynamic collapse models have some observable component to them that make them testable. It appears they are falsified. Many Worlds Interpretation and the Hugh Everett idea has no such thing. It is not testable; it is in a way "safe" from falsification.

LC

[John Clark]

On Tue, Oct 25, 2022 at 6:21 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

> The dynamic collapse models have some observable component to them that make them testable. It appears they are falsified. Many Worlds Interpretation and the Hugh Everett idea has no such thing. It is not testable; it is in a way "safe" from falsificat

There is no way to falsify the conventional Copenhagen interpretation, but back in 1986 in his book "The Ghost in the Atom" David Deutsch proposed a way to falsify Everett's Many Worlds; the experiment would be difficult to perform but Deutsch argues that is not Many Worlds fault, the reason it's so difficult is that the conventional view says conscious observers obey different laws of physics, Many Worlds says they do not, so to test who's right we need a mind that uses quantum properties.

In Deutsch's experiment, to prove or disprove the existence of many worlds other than this one, a conscious quantum computer shoots electrons at a metal plate that has 2 small slits in it. It does this one at a time. The quantum computer has detectors near each slit so it knows which slit the various electrons went through. The quantum mind now signs a document for each and every electron saying it has observed the electron and knows which slit it went through. It is very important that the document does NOT say which slit the electron went through, it only says that it went through one and only one slit and the mind has knowledge of which one. Now just before the electron hits the plate the mind uses quantum erasure to completely destroy the memory of what slits the electrons went through, but all other memories including all the documents remain undamaged. After the document is signed the electron continues on its way and hits the photographic plate. Then after thousands of electrons have been observed and all which-way information has been erased, develop the photographic plate and look at it. If you see interference bands then the many world interpretation is correct. If you do not see interference bands then there are no worlds but this one and the conventional interpretation is correct.

Deutsch is saying that in the Copenhagen interpretation when the results of a measurement enters the consciousness of an observer the wave function collapses, in effect all the universes except one disappear without a trace so you get no interference. In the many worlds model all the other worlds will converge back into one universe when the electrons hit the photographic film because the two universes will no longer be different (even though they had different histories), but their influence will still be felt. In the merged universe you'll see indications that the electron went through slot X only and indications that it went through slot Y only, and that's what causes interference.

I know that what I said in the above is a fair representation of what Deutsch was saying because some years ago I wrote to him about this and he said it was an accurate paraphrase.

John K Clark    See what's on my new list at  Extropolis

74c

[Bruce Kellett]

On Wed, Oct 26, 2022 at 5:41 AM John Clark <johnk...@gmail.com> wrote:

There is no way to falsify the conventional Copenhagen interpretation, but back in 1986 in his book "The Ghost in the Atom" David Deutsch proposed a way to falsify Everett's Many Worlds; the experiment would be difficult to perform but Deutsch argues that is not Many Worlds fault, the reason it's so difficult is that the conventional view says conscious observers obey different laws of physics, Many Worlds says they do not, so to test who's right we need a mind that uses quantum properties.

In Deutsch's experiment, to prove or disprove the existence of many worlds other than this one, a conscious quantum computer shoots electrons at a metal plate that has 2 small slits in it. It does this one at a time. The quantum computer has detectors near each slit so it knows which slit the various electrons went through. The quantum mind now signs a document for each and every electron saying it has observed the electron and knows which slit it went through. It is very important that the document does NOT say which slit the electron went through, it only says that it went through one and only one slit and the mind has knowledge of which one. Now just before the electron hits the plate the mind uses quantum erasure to completely destroy the memory of what slits the electrons went through, but all other memories including all the documents remain undamaged. After the document is signed the electron continues on its way and hits the photographic plate. Then after thousands of electrons have been observed and all which-way information has been erased, develop the photographic plate and look at it. If you see interference bands then the many world interpretation is correct. If you do not see interference bands then there are no worlds but this one and the conventional interpretation is correct.

Deutsch is saying that in the Copenhagen interpretation when the results of a measurement enters the consciousness of an observer the wave function collapses, in effect all the universes except one disappear without a trace so you get no interference. In the many worlds model all the other worlds will converge back into one universe when the electrons hit the photographic film because the two universes will no longer be different (even though they had different histories), but their influence will still be felt. In the merged universe you'll see indications that the electron went through slot X only and indications that it went through slot Y only, and that's what causes interference.

I know that what I said in the above is a fair representation of what Deutsch was saying because some years ago I wrote to him about this and he said it was an accurate paraphrase.

One of the main troubles with this is that the Copenhagen Interpretation, insofar as there is any such thing, does not entail that the wave function collapses when the result enters consciousness. This was a mad idea put forward by Wigner, and it was soon realized that the idea was just silly, and could never work. So that idea has long been abandoned. Deutsch's attempted proof involves comparison with an abandoned idea of quantum mechanics, so it doesn't really prove anything. Besides, the whole set-up involves assumptions about quantum computers and consciousness that are far from obvious, and probably not even correct.

Bruce

[John Clark]

On Tue, Oct 25, 2022 at 5:31 PM Bruce Kellett <bhkel...@gmail.com> wrote:

> One of the main troubles with this is that the Copenhagen Interpretation, insofar as there is any such thing, does not entail that the wave function collapses when the result enters consciousness. This was a mad idea put forward by Wigner, and it was soon realized that the idea was just silly, and could never work. So that idea has long been abandoned. Deutsch's attempted proof involves comparison with an abandoned idea of quantum mechanics, so it doesn't really prove anything. Besides, the whole set-up involves assumptions about quantum computers and consciousness that are far from obvious, and probably not even correct.

 

OK, so forget about consciousness, the fact remains that If you see interference bands on Deutsch's photographic plate then that would prove a universe can split and, provided the difference between them is very small, can under the right conditions become identical again and thus merge back together. That is the key part of the multiverse idea and if it's true then there is no need to indulge in the mumbo-jumbo of Copenhagen quantum complementarity.

So if the experiment was actually performed, what is your guess would happen, what would you place your money on, would there be interference bands on that photographic plate or would there not be?  My guess is that you would see interference bands, I would not bet my life on it or even my house, but I would be willing to bet a week's salary. 

John K Clark    See what's on my new list at  Extropolis

73v

74c

[Bruce Kellett]

On Wed, Oct 26, 2022 at 9:00 AM John Clark <johnk...@gmail.com> wrote:

On Tue, Oct 25, 2022 at 5:31 PM Bruce Kellett <bhkel...@gmail.com> wrote:

> One of the main troubles with this is that the Copenhagen Interpretation, insofar as there is any such thing, does not entail that the wave function collapses when the result enters consciousness. This was a mad idea put forward by Wigner, and it was soon realized that the idea was just silly, and could never work. So that idea has long been abandoned. Deutsch's attempted proof involves comparison with an abandoned idea of quantum mechanics, so it doesn't really prove anything. Besides, the whole set-up involves assumptions about quantum computers and consciousness that are far from obvious, and probably not even correct.

 

OK, so forget about consciousness, the fact remains that If you see interference bands on Deutsch's photographic plate then that would prove a universe can split and, provided the difference between them is very small, can under the right conditions become identical again and thus merge back together. That is the key part of the multiverse idea and if it's true then there is no need to indulge in the mumbo-jumbo of Copenhagen quantum complementarity.

That is as much mumbo-jumbo as anything in Copenhagen. For instance, what determines if the difference between the worlds is small 'enough'? You are using the result of no divergence between worlds to conclude something about a divergence that probably never occurred. It is simpler to state that no measurement was made in the Deutsch set-up. Measurement, after all, involves irreversible decoherence, and such cannot be 'quantum erased'. So no which-way measurement would have been made in the Deutsch experiment. "Measurement" requires the formation of permanent records in the environment (and many copies of the result can be formed as well).

So if the experiment was actually performed, what is your guess would happen, what would you place your money on, would there be interference bands on that photographic plate or would there not be?  My guess is that you would see interference bands, I would not bet my life on it or even my house, but I would be willing to bet a week's salary.

I, too, would expect to see interference bands, because no which-way measurement would have been made in that set-up.

Bruce

[John Clark]

On Tue, Oct 25, 2022 at 6:14 PM Bruce Kellett <bhkel...@gmail.com> wrote:

> That is as much mumbo-jumbo as anything in Copenhagen. For instance, what determines if the difference between the worlds is small 'enough'?

If only a tiny change has been made then it's not unlikely that another tiny change can change it back, but the more changes that occur the less likely it is that will happen. It's rather like thermodynamics, if you watch a movie of just 2 pool balls colliding you can't tell if the movie is running forwards or backwards, but if you watch a movie of a pool ball hitting 10 pool balls arranged in a geometrical pattern then it's easy to tell if the movie is running forwards or backwards. The more changes there are between the 2 universes the less likely it is for them to merge back together again, and the changes multiply very rapidly, that's why performing these sorts of quantum experiments are difficult.    

> You are using the result of no divergence between worlds to conclude something about a divergence that probably never occurred. It is simpler to state that no measurement was made in the Deutsch set-up. Measurement, after all, involves irreversible decoherence, and such cannot be 'quantum erased'. So no which-way measurement would have been made in the Deutsch experiment.

If no which-way measurement has been made then how do you explain the document that swears that such a measurement HAD been made?  

John K Clark    See what's on my new list at  Extropolis

dah

73v

[Bruce Kellett]

No such document can exist since no measurement was made. Or, if such a document exists, it is fraudulent. Quantum erasure experiments do not prove MWI.

Bruce

[John Clark]

On Tue, Oct 25, 2022 at 6:43 PM Bruce Kellett <bhkel...@gmail.com> wrote:

>> If no which-way measurement has been made then how do you explain the document that swears that such a measurement HAD been made?  

> No such document can exist since no measurement was made. 

So if such a document is produced then that would prove that you are wrong.  Would you bet your life that you are right and such a document could not exist, or if not your life would you bet your house? Or would you be more conservative like me and just bet a week's salary? I think such a document could exist, 

> Or, if such a document exists, it is fraudulent.

If the experiment is performed many times and the results are always the same are you proposing there is some universal law that requires the universe always be lying to us?  It's sort of reminds me of the Bible thumpers who say God planted dinosaur bones in the Earth just 6000 years ago to test our faith.

John K Clark    See what's on my new list at  Extropolis

tof

dah

[smitra]

On 26-10-2022 00:14, Bruce Kellett wrote:
> On Wed, Oct 26, 2022 at 9:00 AM John Clark <johnk...@gmail.com>
> wrote:
>
>> On Tue, Oct 25, 2022 at 5:31 PM Bruce Kellett
>> <bhkel...@gmail.com> wrote:
>>

>>> _> One of the main troubles with this is that the Copenhagen

>>> Interpretation, insofar as there is any such thing, does not
>>> entail that the wave function collapses when the result enters
>>> consciousness. This was a mad idea put forward by Wigner, and it
>>> was soon realized that the idea was just silly, and could never
>>> work. So that idea has long been abandoned. Deutsch's attempted
>>> proof involves comparison with an abandoned idea of quantum
>>> mechanics, so it doesn't really prove anything. Besides, the whole
>>> set-up involves assumptions about quantum computers and
>>> consciousness that are far from obvious, and probably not even

>>> correct._

>>
>> OK, so forget about consciousness, the fact remains that If you see
>> interference bands on Deutsch's photographic plate then that would
>> prove a universe can split and, provided the difference between them
>> is very small, can under the right conditions become identical again
>> and thus merge back together. That is the key part of the multiverse
>> idea and if it's true then there is no need to indulge in the
>> mumbo-jumbo of Copenhagen quantum complementarity.
>
> That is as much mumbo-jumbo as anything in Copenhagen. For instance,
> what determines if the difference between the worlds is small
> 'enough'? You are using the result of no divergence between worlds to
> conclude something about a divergence that probably never occurred. It
> is simpler to state that no measurement was made in the Deutsch
> set-up. Measurement, after all, involves irreversible decoherence, and
> such cannot be 'quantum erased'. So no which-way measurement would
> have been made in the Deutsch experiment. "Measurement" requires the
> formation of permanent records in the environment (and many copies of
> the result can be formed as well).
>

There is no such thing as irreversible decoherence in unitary QM. Now,
you and Brent have invoked the expansion of the universe in past
discussions to argue that fundamentally irreversible phenomena do exist.
However this reasoning is flawed, because you then assume a
semi-classical model where the expansion of the universe is described in
a classical way. If QM is fundamental, then the entire state of the
universe, including the space-time geometry is part of that quantum
description. You then have a wavefunctional that assigns a complex
amplitude to the entire state of the universe that includes al the
fields of all particles and also the space-time geometry.


Thing is that the laws of physics are what they are. You cannot demand
that you require measurement results to be truly permanent and that they
therefore arise due to irreversible processes. Whether that's the case
or not is determined by the laws of physics, not by us.

Saibal

>> So if the experiment was actually performed, what is your guess
>> would happen, what would you place your money on, would there be
>> interference bands on that photographic plate or would there not be?
>> My guess is that you would see interference bands, I would not bet
>> my life on it or even my house, but I would be willing to bet a
>> week's salary.
>
> I, too, would expect to see interference bands, because no which-way
> measurement would have been made in that set-up.
>
> Bruce
>

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[Bruce Kellett]

I think you need to do some research on delayed choice and quantum erasure experiments. These experiments have been done and are essentially equivalent to Deutsch's thought experiment. There is no mystery in interpreting these experiments. In all cases, if the which-way information is preserved, no interference is seen. But if the which-way information is quantum erased, interference is visible. How this works in the delayed choice set-up has been explained by Sabine Hossenfelder.

http://backreaction.blogspot.com/2021/10/the-delayed-choice-quantum-eraser.html

Bruce

[Bruce Kellett]

On Wed, Oct 26, 2022 at 10:15 AM smitra <smi...@zonnet.nl> wrote:

On 26-10-2022 00:14, Bruce Kellett wrote:

There is no such thing as irreversible decoherence in unitary QM. Now,
you and Brent have invoked the expansion of the universe in past
discussions to argue that fundamentally irreversible phenomena do exist.
However this reasoning is flawed, because you then assume a
semi-classical model where the expansion of the universe is described in
a classical way. If QM is fundamental, then the entire state of the
universe, including the space-time geometry is part of that quantum
description. You then have a wavefunctional that assigns a complex
amplitude to the entire state of the universe that includes al the
fields of all particles and also the space-time geometry.


Thing is that the laws of physics are what they are. You cannot demand
that you require measurement results to be truly permanent and that they
therefore arise due to irreversible processes. Whether that's the case
or not is determined by the laws of physics, not by us.

The laws of physics tell us that measurements are irreversible. Unitary evolution is universal only in your imagination. Many Worlds is an interpretation, not an established fact.

Bruce

[Brent Meeker]

On 10/25/2022 11:40 AM, John Clark wrote:

On Tue, Oct 25, 2022 at 6:21 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

> The dynamic collapse models have some observable component to them that make them testable. It appears they are falsified. Many Worlds Interpretation and the Hugh Everett idea has no such thing. It is not testable; it is in a way "safe" from falsificat

There is no way to falsify the conventional Copenhagen interpretation, but back in 1986 in his book "The Ghost in the Atom" David Deutsch proposed a way to falsify Everett's Many Worlds; the experiment would be difficult to perform but Deutsch argues that is not Many Worlds fault, the reason it's so difficult is that the conventional view says conscious observers obey different laws of physics, Many Worlds says they do not, so to test who's right we need a mind that uses quantum properties.

In Deutsch's experiment, to prove or disprove the existence of many worlds other than this one, a conscious quantum computer shoots electrons at a metal plate that has 2 small slits in it. It does this one at a time. The quantum computer has detectors near each slit so it knows which slit the various electrons went through. The quantum mind now signs a document for each and every electron saying it has observed the electron and knows which slit it went through. It is very important that the document does NOT say which slit the electron went through, it only says that it went through one and only one slit and the mind has knowledge of which one. Now just before the electron hits the plate the mind uses quantum erasure to completely destroy the memory of what slits the electrons went through, but all other memories including all the documents remain undamaged. After the document is signed the electron continues on its way and hits the photographic plate. Then after thousands of electrons have been observed and all which-way information has been erased, develop the photographic plate and look at it. If you see interference bands then the many world interpretation is correct. If you do not see interference bands then there are no worlds but this one and the conventional interpretation is correct.

It would be trivially easy to create an AI (not even a smart one) to do this. It's just a quantum erasure Young's slit experiment with a module what  prints out a document saying the which-way information known before erasure.  I

Deutsch is saying that in the Copenhagen interpretation when the results of a measurement enters the consciousness of an observer the wave function collapses,

That was Wigner's idea, which he later rejected.  Certainly Bohr never thought the consciousness was necessary to collapse the wave function.  He thought any record of which-way would destroy the  interference.  This has subsequently been shown in experiments like the Buckyball double slit and is given theoretical support by decoherence theory.

Brent

in effect all the universes except one disappear without a trace so you get no interference. In the many worlds model all the other worlds will converge back into one universe when the electrons hit the photographic film because the two universes will no longer be different (even though they had different histories), but their influence will still be felt. In the merged universe you'll see indications that the electron went through slot X only and indications that it went through slot Y only, and that's what causes interference.

I know that what I said in the above is a fair representation of what Deutsch was saying because some years ago I wrote to him about this and he said it was an accurate paraphrase.

John K Clark    See what's on my new list at  Extropolis

74c

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[Brent Meeker]

On 10/25/2022 3:00 PM, John Clark wrote:

On Tue, Oct 25, 2022 at 5:31 PM Bruce Kellett <bhkel...@gmail.com> wrote:

> One of the main troubles with this is that the Copenhagen Interpretation, insofar as there is any such thing, does not entail that the wave function collapses when the result enters consciousness. This was a mad idea put forward by Wigner, and it was soon realized that the idea was just silly, and could never work. So that idea has long been abandoned. Deutsch's attempted proof involves comparison with an abandoned idea of quantum mechanics, so it doesn't really prove anything. Besides, the whole set-up involves assumptions about quantum computers and consciousness that are far from obvious, and probably not even correct.

 

OK, so forget about consciousness, the fact remains that If you see interference bands on Deutsch's photographic plate then that would prove a universe can split

No it doesn't.  The would be no evidence that the universe split.  Interference implies that the every particle went thru both slits and interfered with itself...not at all surprising once you  adopt quantum field theory in which particles are just field quanta.

Brent

and, provided the difference between them is very small, can under the right conditions become identical again and thus merge back together. That is the key part of the multiverse idea and if it's true then there is no need to indulge in the mumbo-jumbo of Copenhagen quantum complementarity.

So if the experiment was actually performed, what is your guess would happen, what would you place your money on, would there be interference bands on that photographic plate or would there not be?  My guess is that you would see interference bands, I would not bet my life on it or even my house, but I would be willing to bet a week's salary. 

John K Clark    See what's on my new list at  Extropolis

73v

74c

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[Brent Meeker]

Why would you believe the document was correct?

Brent

John K Clark    See what's on my new list at  Extropolis

dah

73v

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[Brent Meeker]

I'm reminded of the guy who claimed he had gone to heaven and returned and cited a book saying so as proof.

Brent

John K Clark    See what's on my new list at  Extropolis

tof

dah

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[Brent Meeker]

That assumes that the long sought quantum theory of gravity will not
break unitarity.  There are already proposals for this
https://arxiv.org/pdf/2201.11658.pdf

Brent

[Brent Meeker]

On 10/25/2022 4:36 PM, Bruce Kellett wrote:

On Wed, Oct 26, 2022 at 10:01 AM John Clark <johnk...@gmail.com> wrote:

On Tue, Oct 25, 2022 at 6:43 PM Bruce Kellett <bhkel...@gmail.com> wrote:

>> If no which-way measurement has been made then how do you explain the document that swears that such a measurement HAD been made?  

> No such document can exist since no measurement was made. 

So if such a document is produced then that would prove that you are wrong.  Would you bet your life that you are right and such a document could not exist, or if not your life would you bet your house? Or would you be more conservative like me and just bet a week's salary? I think such a document could exist, 

> Or, if such a document exists, it is fraudulent.

If the experiment is performed many times and the results are always the same are you proposing there is some universal law that requires the universe always be lying to us?  It's sort of reminds me of the Bible thumpers who say God planted dinosaur bones in the Earth just 6000 years ago to test our faith.

I think you need to do some research on delayed choice and quantum erasure experiments. These experiments have been done and are essentially equivalent to Deutsch's thought experiment.

The only difference is Deutsch attaches a printer that keeps printing "I saw which slit that one went thru."

Brent

There is no mystery in interpreting these experiments. In all cases, if the which-way information is preserved, no interference is seen. But if the which-way information is quantum erased, interference is visible. How this works in the delayed choice set-up has been explained by Sabine Hossenfelder.

http://backreaction.blogspot.com/2021/10/the-delayed-choice-quantum-eraser.html

Bruce

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[Bruce Kellett]

On Wed, Oct 26, 2022 at 4:46 PM Brent Meeker <meeke...@gmail.com> wrote:

On 10/25/2022 4:36 PM, Bruce Kellett wrote:

On Wed, Oct 26, 2022 at 10:01 AM John Clark <johnk...@gmail.com> wrote:

On Tue, Oct 25, 2022 at 6:43 PM Bruce Kellett <bhkel...@gmail.com> wrote: 

I think you need to do some research on delayed choice and quantum erasure experiments. These experiments have been done and are essentially equivalent to Deutsch's thought experiment.

The only difference is Deutsch attaches a printer that keeps printing "I saw which slit that one went thru."

I can write a trivial program that does that --  no need to attach it to any experiment.

Bruce

[Brent Meeker]

My point exactly.

Bruce

[Lawrence Crowell]

On Tuesday, October 25, 2022 at 1:41:05 PM UTC-5 johnk...@gmail.com wrote:

On Tue, Oct 25, 2022 at 6:21 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

> The dynamic collapse models have some observable component to them that make them testable. It appears they are falsified. Many Worlds Interpretation and the Hugh Everett idea has no such thing. It is not testable; it is in a way "safe" from falsificat

There is no way to falsify the conventional Copenhagen interpretation, but back in 1986 in his book "The Ghost in the Atom" David Deutsch proposed a way to falsify Everett's Many Worlds; the experiment would be difficult to perform but Deutsch argues that is not Many Worlds fault, the reason it's so difficult is that the conventional view says conscious observers obey different laws of physics, Many Worlds says they do not, so to test who's right we need a mind that uses quantum properties.

In Deutsch's experiment, to prove or disprove the existence of many worlds other than this one, a conscious quantum computer shoots electrons at a metal plate that has 2 small slits in it. It does this one at a time. The quantum computer has detectors near each slit so it knows which slit the various electrons went through. The quantum mind now signs a document for each and every electron saying it has observed the electron and knows which slit it went through. It is very important that the document does NOT say which slit the electron went through, it only says that it went through one and only one slit and the mind has knowledge of which one. Now just before the electron hits the plate the mind uses quantum erasure to completely destroy the memory of what slits the electrons went through, but all other memories including all the documents remain undamaged. After the document is signed the electron continues on its way and hits the photographic plate. Then after thousands of electrons have been observed and all which-way information has been erased, develop the photographic plate and look at it. If you see interference bands then the many world interpretation is correct. If you do not see interference bands then there are no worlds but this one and the conventional interpretation is correct.

It has been a long time since I have read about this. As I recall Deutsch's hypothesis involved some scalar field. What you describe I think can be understood independent of any quantum interpretation. 

LC

[Lawrence Crowell]

Unitarity is a group structure, and is a specific case of a groupoid. A groupoid corresponding to different cobordisms that imprint quantum number or information on a manifold. In that way the start and end of the deformation retract my differ by some topological information on this space. This is then a form of isometry inherited by the entire space. 

The idea that unitarity is just a special case of a more general system of diffeomorphisms or isometries is one way that quantum mechanics and gravitation may merge. 

LC

[Lawrence Crowell]

Unless this assignment of slit is accompanied by some sort of entanglement, say some weak measurement puts an additional state into a superposed + or - state, this is indeed meaningless.

LC 

[John Clark]

On Wed, Oct 26, 2022 at 1:35 AM Brent Meeker <meeke...@gmail.com> wrote:

>Why would you believe the document was correct?

Why would you believe the universe is ALWAYS lying to us? Why do you believe the existence of dinosaur bones implies that dinosaurs once existed?  

John K Clark    See what's on my new list at  Extropolis

7xx

[John Clark]

On Tue, Oct 25, 2022 at 7:37 PM Bruce Kellett <bhkel...@gmail.com> wrote:

> In all cases, if the which-way information is preserved, no interference is seen. 

True.

> But if the which-way information is quantum erased, interference is visible. 

Also true ....  but then… why would you say "I, too, would expect to see interference bands" if Deutsch's experiment was actually performed?

> How this works in the delayed choice set-up has been explained by Sabine Hossenfelder.

 

I stopped reading Hossenfelder sometime ago when she started defending Superdeterminism; yes it can explain all the weirdness in the quantum world but it requires, quite literally, the greatest violation of Occam's razor that is possible in order to do so. I would even go so far as to say Superdeterminism requires an INFINITE violation of Occam's razor, and that is not a word I use very often. For that reason I don't see how any rational person could take Superdeterminism seriously.

John K Clark    See what's on my new list at  Extropolis

org

tof

[John Clark]

On Wed, Oct 26, 2022 at 1:34 AM Brent Meeker <meeke...@gmail.com> wrote:

> not at all surprising once you  adopt quantum field theory in which particles are just field quanta.

Even Niels Bohr, the father of the Copenhagen interpretation, said  "if you are not shocked by quantum mechanics then you don't understand it". And Richard Feynman, right after he won the Nobel prize for quantum mechanics, said "I think it's safe to say that nobody understands quantum mechanics''. As for me, I think if Many Worlds is not correct then something even stranger is, perhaps too strange for the human mind to comprehend.

John K Clark    See what's on my new list at  Extropolis

lda

[Bruce Kellett]

On Wed, Oct 26, 2022 at 9:34 PM John Clark <johnk...@gmail.com> wrote:

On Tue, Oct 25, 2022 at 7:37 PM Bruce Kellett <bhkel...@gmail.com> wrote:

> In all cases, if the which-way information is preserved, no interference is seen. 

True.

> But if the which-way information is quantum erased, interference is visible. 

Also true ....  but then… why would you say "I, too, would expect to see interference bands" if Deutsch's experiment was actually performed?

Because no which-way measurement is actually made in the Deutsch set-up.

> How this works in the delayed choice set-up has been explained by Sabine Hossenfelder.

 

I stopped reading Hossenfelder sometime ago when she started defending Superdeterminism; yes it can explain all the weirdness in the quantum world but it requires, quite literally, the greatest violation of Occam's razor that is possible in order to do so. I would even go so far as to say Superdeterminism requires an INFINITE violation of Occam's razor, and that is not a word I use very often. For that reason I don't see how any rational person could take Superdeterminism seriously.

Belief in superdeterminism, or Zoroastrianism, or whatever, does not mean that everything a person writes is nonsense. To believe so is an example of the very worst form of argumentum ad hominem (or feminem in Hossenfelder's case).

Besides, Sean Carroll gives essentially the same explanation from a many-worlds perspective:

https://www.preposterousuniverse.com/blog/?s=quantum+erase

Bruce

[John Clark]

On Wed, Oct 26, 2022 at 7:01 AM Bruce Kellett <bhkel...@gmail.com> wrote:

> In all cases, if the which-way information is preserved, no interference is seen. 

True.

> But if the which-way information is quantum erased, interference is visible. 

> Also true ....  but then… why would you say "I, too, would expect to see interference bands" if Deutsch's experiment was actually performed?

> Because no which-way measurement is actually made in the Deutsch set-up.

Then why does the document insist that there was and why does it keep on insisting no matter how many times the experiment is repeated? Do you think the universe is inherently a liar and NEVER tells the truth?  

>> I stopped reading Hossenfelder sometime ago when she started defending Superdeterminism; yes it can explain all the weirdness in the quantum world but it requires, quite literally, the greatest violation of Occam's razor that is possible in order to do so. I would even go so far as to say Superdeterminism requires an INFINITE violation of Occam's razor, and that is not a word I use very often. For that reason I don't see how any rational person could take Superdeterminism seriously.

> Belief in superdeterminism, or Zoroastrianism, or whatever, does not mean that everything a person writes is nonsense. To believe so is an example of the very worst form of argumentum ad hominem 

 

Don't give me that crap! Are you really claiming that I don't have the right to stop reading somebody if I choose to? It's relevant because Many Worlds and Superdeterminism are competitors, and Superdeterminism is as utterly ridiculous as saying "because of God" is the answer to all of life's mysteries.

> (or feminem in Hossenfelder's case).

If I criticize a physicist who happens to be black or a woman that does not  necessarily mean that I'm a racist or a misogynist, and to claim it does is a very fine example of an argument by ad hominem.

> Besides, Sean Carroll gives essentially the same explanation from a many-worlds perspective:

https://www.preposterousuniverse.com/blog/?s=quantum+erase

If it really is "essentially the same explanation" then obviously it does not contradict Deutsch's proposed experiment because Carroll is one of the most vigorous advocates of Everett's many worlds idea, he wrote an entire book about it, a very good book.

John K Clark    See what's on my new list at  Extropolis

8gx

 

[spudb...@aol.com]

I will introduce you to Stephon Alexander, & Ediho Lokanga. Both guys are physicists and dwell intensely on the observer moment side of things. Let's say you may not, LC doesn't, but these dudes do!

Dr. Stephon Alexander | Faculty Profile | Chapman University

https://euclid.academia.edu/EdihoLokanga

Now these guys integrate conscious observation with the universe.

You can hate it, but, can you disprove it, say I? 

Any, viewers here should consider adding them to their reading list.

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[Bruce Kellett]

On Wed, Oct 26, 2022 at 10:32 PM John Clark <johnk...@gmail.com> wrote:

On Wed, Oct 26, 2022 at 7:01 AM Bruce Kellett <bhkel...@gmail.com> wrote:

> In all cases, if the which-way information is preserved, no interference is seen. 

True.

> But if the which-way information is quantum erased, interference is visible. 

> Also true ....  but then… why would you say "I, too, would expect to see interference bands" if Deutsch's experiment was actually performed?

> Because no which-way measurement is actually made in the Deutsch set-up.

Then why does the document insist that there was and why does it keep on insisting no matter how many times the experiment is repeated? Do you think the universe is inherently a liar and NEVER tells the truth?  

Maybe the experiment does not do what you think it does.

>> I stopped reading Hossenfelder sometime ago when she started defending Superdeterminism; yes it can explain all the weirdness in the quantum world but it requires, quite literally, the greatest violation of Occam's razor that is possible in order to do so. I would even go so far as to say Superdeterminism requires an INFINITE violation of Occam's razor, and that is not a word I use very often. For that reason I don't see how any rational person could take Superdeterminism seriously.

> Belief in superdeterminism, or Zoroastrianism, or whatever, does not mean that everything a person writes is nonsense. To believe so is an example of the very worst form of argumentum ad hominem 

 

Don't give me that crap! Are you really claiming that I don't have the right to stop reading somebody if I choose to?

You can read or not read whoever you want.  But that is not an argument against any views that they might express.

It's relevant because Many Worlds and Superdeterminism are competitors, and Superdeterminism is as utterly ridiculous as saying "because of God" is the answer to all of life's mysteries.

> (or feminem in Hossenfelder's case).

If I criticize a physicist who happens to be black or a woman that does not  necessarily mean that I'm a racist or a misogynist, and to claim it does is a very fine example of an argument by ad hominem.

> Besides, Sean Carroll gives essentially the same explanation from a many-worlds perspective:

https://www.preposterousuniverse.com/blog/?s=quantum+erase

If it really is "essentially the same explanation" then obviously it does not contradict Deutsch's proposed experiment because Carroll is one of the most vigorous advocates of Everett's many worlds idea, he wrote an entire book about it, a very good book.

Deutsch's proposal does not "test many worlds", and Carroll makes no such claim. Sean simply explains delayed choice and the quantum eraser as straightforward quantum effects that are not in the least mysterious. They do not depend on any particular interpretation of quantum mechanics.

Bruce

[Lawrence Crowell]

I would have to research this, but as I remember Deutsch's argument involved some sort of scalar variable or field that was involved with how many world splitting occurred nonlocally.

LC 

[Brent Meeker]

On 10/26/2022 4:00 AM, Bruce Kellett wrote:

On Wed, Oct 26, 2022 at 9:34 PM John Clark <johnk...@gmail.com> wrote:

On Tue, Oct 25, 2022 at 7:37 PM Bruce Kellett <bhkel...@gmail.com> wrote:

> In all cases, if the which-way information is preserved, no interference is seen. 

True.

> But if the which-way information is quantum erased, interference is visible. 

Also true ....  but then… why would you say "I, too, would expect to see interference bands" if Deutsch's experiment was actually performed?

Because no which-way measurement is actually made in the Deutsch set-up.

> How this works in the delayed choice set-up has been explained by Sabine Hossenfelder.

 

I stopped reading Hossenfelder sometime ago when she started defending Superdeterminism; yes it can explain all the weirdness in the quantum world but it requires, quite literally, the greatest violation of Occam's razor that is possible in order to do so. I would even go so far as to say Superdeterminism requires an INFINITE violation of Occam's razor, and that is not a word I use very often. For that reason I don't see how any rational person could take Superdeterminism seriously.

Yet you happily swallow a theory which postulates that EVERYTHING nomologically possible happens?

Brent

[Brent Meeker]

On 10/26/2022 3:15 AM, John Clark wrote:

On Wed, Oct 26, 2022 at 1:35 AM Brent Meeker <meeke...@gmail.com> wrote:

>Why would you believe the document was correct?

Why would you believe the universe is ALWAYS lying to us? Why do you believe the existence of dinosaur bones implies that dinosaurs once existed? 

It isn't "The Universe" that is producing this document.  It's some AI that Deutsch postulates is conscious, can measure a quantum variable, erase the measurement, but remember that it knew the value and writes a message saying so.  Yeah, I'm sure that'll work

Brent

[John Clark]

On Wed, Oct 26, 2022 at 5:55 PM Bruce Kellett <bhkel...@gmail.com> wrote:

>> Then why does the document insist that there was and why does it keep on insisting no matter how many times the experiment is repeated? Do you think the universe is inherently a liar and NEVER tells the truth?  

> Maybe the experiment does not do what you think it does.

Is that really the best defense you can come up with? Maybe maybe maybe.... If you're desperate enough you can say the same thing about ANY experiment  ... Maybe the existence of dinosaur bones doesn't imply that dinosaurs once existed, maybe they were put there by God 6000 years ago to fool us, and being omnipotent He obviously had no trouble doing so.

 > Sean simply explains delayed choice and the quantum eraser as straightforward quantum effects that are not in the least mysterious.

 "Anyone who is not shocked by quantum mechanics has not understood it." : Niels Bohr

   John K Clark    See what's on my new list at  Extropolis

9hg

[John Clark]

On Wed, Oct 26, 2022 at 10:39 PM Brent Meeker <meeke...@gmail.com> wrote:

> I don't see how any rational person could take Superdeterminism seriously.

 

> Yet you happily swallow a theory which postulates that EVERYTHING nomologically possible happens?

Correct, I swallow the Many World's idea even though I freely admit the idea is bazaar because any correct explanation for the weirdness of Quantum Mechanics is going to be bizarre. However I prefer a theory that keeps outlandishness to a minimum, and nothing, absolutely nothing, is more outlandish than an INFINITE violation of Occam's razor; and that is exactly what superdeterminism is all about. Even Copenhagen is not as ridiculous as that. 

John K Clark    See what's on my new list at  Extropolis

ecr

[John Clark]

On Thu, Oct 27, 2022 at 12:23 AM Brent Meeker <meeke...@gmail.com> wrote:

>> Why would you believe the universe is ALWAYS lying to us? Why do you believe the existence of dinosaur bones implies that dinosaurs once existed?

 

> It isn't "The Universe" that is producing this document.  It's some AI that Deutsch postulates is conscious, can measure a quantum variable, erase the measurement, but remember that it knew the value and writes a message saying so.  Yeah, I'm sure that'll work

Forget consciousness. You program a computer to make a measurement about which slit an electron goes through, if the machine is able to make the measurement you program it to produce a document saying it has knowledge of which slit the electron went through but does not state which slit that is, and you program the computer to then use quantum erasure to get rid of that which-way information but to leave the document intact. Every time you and many other people perform this experiment using their own equipment and their own independently written program interference bands are always seen and a document insisting that a which-way measurement has been successfully completed is also always seen. At this point a rational person would have to conclude that either Many Worlds is correct or the universe is a liar. And if the universe is a liar then it's time to give up on science.

John K Clark    See what's on my new list at  Extropolis

0mo

0mo

 

 

[Brent Meeker]

On 10/27/2022 5:10 AM, John Clark wrote:

On Thu, Oct 27, 2022 at 12:23 AM Brent Meeker <meeke...@gmail.com> wrote:

>> Why would you believe the universe is ALWAYS lying to us? Why do you believe the existence of dinosaur bones implies that dinosaurs once existed?

 

> It isn't "The Universe" that is producing this document.  It's some AI that Deutsch postulates is conscious, can measure a quantum variable, erase the measurement, but remember that it knew the value and writes a message saying so.  Yeah, I'm sure that'll work

Forget consciousness. You program a computer to make a measurement about which slit an electron goes through, if the machine is able to make the measurement you program it to produce a document saying it has knowledge of which slit the electron went through but does not state which slit that is, and you program the computer to then use quantum erasure to get rid of that which-way information but to leave the document intact.

But, as pointed out by Carroll in his explication of the delayed choice quantum experiment, "...make the measurement you program it to produce a document saying it has knowledge of which slit the electron went through..." this can't be a real measurement, because that would imply a record of it.  If it done just by correlating with a quantum variable that can be erased it's not a measurement.  Deutsch's whole idea depends on it being conscious of this measurement because that obfuscates what can and can't be erased.  It's trivial to hook up a machine that just prints out "I measured it." every time an electron comes by; but then how do you know whether it was really conscious?  Do you believe in immaterial consciousness that is distinct from the material intelligence which knows things?  You forget things and so you could measure something and then remember you measured it but forget the value, but you can't quantum erase the value measured...it just got decohered.

Brent

Every time you and many other people perform this experiment using their own equipment and their own independently written program interference bands are always seen and a document insisting that a which-way measurement has been successfully completed is also always seen. At this point a rational person would have to conclude that either Many Worlds is correct or the universe is a liar. And if the universe is a liar then it's time to give up on science.

John K Clark    See what's on my new list at  Extropolis

0mo

0mo

 

 

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[John Clark]

On Thu, Oct 27, 2022 at 5:05 PM Brent Meeker <meeke...@gmail.com> wrote:

> as pointed out by Carroll in his explication of the delayed choice quantum experiment, "...make the measurement you program it to produce a document saying it has knowledge of which slit the electron went through..." this can't be a real measurement, because that would imply a record of it.  

But there WAS a record of which slit the electron went through when the document was written,  that is how the machine got the information that enabled it to say it knew which way the electron went. It was only after that  the information was erased.

> If it done just by correlating with a quantum variable that can be erased it's not a measurement. 

Then why did the computer that you programmed say a measurement had been done?  Any information can be stored quantum mechanically and if a computer stores that information quantum mechanically, which conventional computers do not do, then that information can be erased. 

 > Deutsch's whole idea depends on it being conscious of this measurement because that obfuscates what can and can't be erased.  

No. The only reason Deutsch mentions consciousness is that some rival theories to Many Worlds think consciousness has something to do with the question at hand, but if you're like Deutsch and me and believe consciousness is irrelevant when talking about the foundations of quantum mechanics then forget about consciousness and think about the computer as just a scientific instrument that works on quantum mechanical principles. 

> It's trivial to hook up a machine that just prints out "I measured it."

Obviously, but do you really think that's what Deutsch was proposing, do you really think he's that stupid? Instead you program the computer to perform the best measurement possible, and if it is able to determine which slit the electron went through the machine writes a document saying it knows which way the electron went through, but of course it does not specify which slit that was; and if for some reason it is unable to make the measurement it writes a document saying it was unable to make that measurement. Then after the electron passes through the slits but before it hits the photographic plate the witch-way information is erased. So when the photographic plate is developed and if you see interference bands then you know there must be other worlds than this one, and if you don't see interference bands then the Many Worlds idea is bullshit. 

> You forget things and so you could measure something and then remember you measured it but forget the value, but you can't quantum erase the value measured...it just got decohered.

Decoherence usually spreads with enormous speed but if things are arranged very carefully, if only one electron in the universe got decohered, then it's possible the electron could become re-cohered because in the Many Worlds theory it makes no sense to talk about two identical universes, so if the witch-way information of that electron has been erased then there's no longer any difference between the two universes and they merge back together. 

John K Clark    See what's on my new list at  Extropolis

u6g

[Brent Meeker]

On 10/27/2022 3:01 PM, John Clark wrote:

On Thu, Oct 27, 2022 at 5:05 PM Brent Meeker <meeke...@gmail.com> wrote:

> as pointed out by Carroll in his explication of the delayed choice quantum experiment, "...make the measurement you program it to produce a document saying it has knowledge of which slit the electron went through..." this can't be a real measurement, because that would imply a record of it.  

But there WAS a record of which slit the electron went through when the document was written,  that is how the machine got the information that enabled it to say it knew which way the electron went. It was only after that  the information was erased.

> If it done just by correlating with a quantum variable that can be erased it's not a measurement. 

Then why did the computer that you programmed say a measurement had been done?  Any information can be stored quantum mechanically and if a computer stores that information quantum mechanically, which conventional computers do not do, then that information can be erased. 

 > Deutsch's whole idea depends on it being conscious of this measurement because that obfuscates what can and can't be erased.  

No. The only reason Deutsch mentions consciousness is that some rival theories to Many Worlds think consciousness has something to do with the question at hand, but if you're like Deutsch and me and believe consciousness is irrelevant when talking about the foundations of quantum mechanics then forget about consciousness and think about the computer as just a scientific instrument that works on quantum mechanical principles. 

> It's trivial to hook up a machine that just prints out "I measured it."

Obviously, but do you really think that's what Deutsch was proposing, do you really think he's that stupid?

No.  I mention it to point out that the crux of the question is exactly how this information can be both measured and erased and documented.  That this is not a trivial "Well I can remember seeing something but not what I saw" hand waving problem.  And I think that if you actually devised a way to doing it in qubits it will turn out like Carroll's explanation to be completely independent of whether MWI is right or not.

Brent

Instead you program the computer to perform the best measurement possible, and if it is able to determine which slit the electron went through the machine writes a document saying it knows which way the electron went through, but of course it does not specify which slit that was; and if for some reason it is unable to make the measurement it writes a document saying it was unable to make that measurement. Then after the electron passes through the slits but before it hits the photographic plate the witch-way information is erased. So when the photographic plate is developed and if you see interference bands then you know there must be other worlds than this one, and if you don't see interference bands then the Many Worlds idea is bullshit. 

> You forget things and so you could measure something and then remember you measured it but forget the value, but you can't quantum erase the value measured...it just got decohered.

Decoherence usually spreads with enormous speed but if things are arranged very carefully, if only one electron in the universe got decohered, then it's possible the electron could become re-cohered because in the Many Worlds theory it makes no sense to talk about two identical universes, so if the witch-way information of that electron has been erased then there's no longer any difference between the two universes and they merge back together. 

John K Clark    See what's on my new list at  Extropolis

u6g

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[Bruce Kellett]

On Fri, Oct 28, 2022 at 9:02 AM John Clark <johnk...@gmail.com> wrote:

Then after the electron passes through the slits but before it hits the photographic plate the witch-way information is erased. So when the photographic plate is developed and if you see interference bands then you know there must be other worlds than this one, and if you don't see interference bands then the Many Worlds idea is bullshit. 

Decoherence usually spreads with enormous speed but if things are arranged very carefully, if only one electron in the universe got decohered, then it's possible the electron could become re-cohered because in the Many Worlds theory it makes no sense to talk about two identical universes, so if the witch-way information of that electron has been erased then there's no longer any difference between the two universes and they merge back together.

This idea that quantum erasure allows two universes to recombine to produce the interference pattern (which you have got from the early writings of David Deutsch, I know) is complete nonsense. It is completely demolished by the delayed choice experiments. You can delay the choice as to whether or not to utilize the information about which slit the particle went through until long after that particle has hit the screen and formed its permanent image on the screen. It cannot decide whether or not to interfere with itself to produce an interference pattern at that time -- the decision about where to hit the screen has long since been made. So there can be no "merging of two separate worlds" at that point.

I cannot recommend strongly enough that you read and study the article by Carroll -- it might rid you of a number of misconceptions that you have built up over time:

https://www.preposterousuniverse.com/blog/?s=quantum+erase

Bruce

[John Clark]

On Thu, Oct 27, 2022 at 6:55 PM Bruce Kellett <bhkel...@gmail.com> wrote:

> You can delay the choice as to whether or not to utilize the information about which slit the particle went through until long after that particle has hit the screen

No you cannot, you must perform the quantum erasure after the particle passes through the slits but before it hits the screen, although that time can be as long as you want it to be, you just have to increase the distance between the slits in the screen. 

 

> and formed its permanent image on the screen.

Once a large-scale macro change  has been made, such as would happen when the particle hits the screen, it would be virtually impossible to get all the trillions of particles in the screen to become identical again and cause the two universes to merge back together again.  

 

> It cannot decide whether or not to interfere with itself to produce an interference pattern at that time -- the decision about where to hit the screen has long since been made.

Huh? You don't get to decide where the particle hits the screen.

> I cannot recommend strongly enough that you read and study the article by Carroll -- it might rid you of a number of misconceptions that you have built up over time:

Misconceptions that apparently you are unable to clearly state. I am very well acquainted with Carroll's blog and I'll wager I've read more stuff by Carroll than you have.

John K Clark    See what's on my new list at  Extropolis

cbr

[spudb...@aol.com]

On pure cosmology, and what we have measured, Carroll is great, a good physicist, but like LC, believes he comprehends what i going on. They don't, even as a physics outsider I can detect this. 

If there's an argument here about quantum erasure, I will go instead of Stanford, I'd head for Harvard, where Strominger hangs his hat. 

https://press.princeton.edu/books/hardcover/9780691179506/lectures-on-the-infrared-structure-of-gravity-and-gauge-theory

Also we now live in a time where we detect that the universe, cosmologically is

The Universe Is Not Locally Real, and the Physics Nobel Prize Winners Proved It

https://www.scientificamerican.com/article/the-universe-is-not-locally-real-and-the-physics-nobel-prize-winners-proved-it/

It doesn't appear that quantum erasure at interstellar levels is accurate? It may be great for computer security though at the chip level however?

Huzzah!

-----Original Message-----
From: John Clark <johnk...@gmail.com>
To: everyth...@googlegroups.com
Sent: Thu, Oct 27, 2022 7:16 pm
Subject: Re: Apparently objective quantum wave function collapse doesn't occur

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[Bruce Kellett]

On Fri, Oct 28, 2022 at 10:17 AM John Clark <johnk...@gmail.com> wrote:

On Thu, Oct 27, 2022 at 6:55 PM Bruce Kellett <bhkel...@gmail.com> wrote:

> You can delay the choice as to whether or not to utilize the information about which slit the particle went through until long after that particle has hit the screen

No you cannot, you must perform the quantum erasure after the particle passes through the slits but before it hits the screen, although that time can be as long as you want it to be, you just have to increase the distance between the slits in the screen.

Look. The experiments have been done, and the act of quantum erasure can be delayed until long after the particles have hit the screen and formed the image there. 

> and formed its permanent image on the screen.

Once a large-scale macro change  has been made, such as would happen when the particle hits the screen, it would be virtually impossible to get all the trillions of particles in the screen to become identical again and cause the two universes to merge back together again.

That is why your notion of erasure as making separate universes recombine falls apart. The choice about what measurement to make can be delayed until long after the pattern is formed on the screen. This is the point of Wheeler's delayed choice idea. If you cannot conceive of how this could possibly be right, then I suggest you overcome your prejudices and look at the account by Sabine Hossenfelder. Or even go so far as to look at the Wikipedia page on quantum erasure. These sources spell out in detail how you can form both interference and non-interference patterns that are resolved only long after the patterns are formed.

Bruce

[Brent Meeker]

Whether you've read it or not, you have not understood the one on delayed-choice quantum erasure.  Notice that he lets the particles hit the screen and then does the erasure by picking out the left-spin v. the right-spin.

Brent

John K Clark    See what's on my new list at  Extropolis

cbr

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[John Clark]

On Thu, Oct 27, 2022 at 8:24 PM Brent Meeker <meeke...@gmail.com> wrote:

> Whether you've read it or not, you have not understood the one on delayed-choice quantum erasure.  Notice that he lets the particles hit the screen and then does the erasure by picking out the left-spin v. the right-spin.

First of all I'm not talking about the delayed choice experiment I'm talking about David Deutsch's proposed experiment, and I very much doubt that Carroll actually said what do you claim, but if he did then I know for a fact that Carroll was dead wrong because the worlds greatest expert on what David Deutsch is trying to say is David Deutsch, and some years ago I said something to him very similar to what you're saying now to professor Deutsch and he corrected me and showed me the error of my ways.

John K Clark    See what's on my new list at  Extropolis

7tr

[Brent Meeker]

I was citing Carroll on the delayed choice quantum erasure...not on anything Deutsch said. 

The problem I see in this is that the computer must make a measurement that does two things

(1) it prints out a document that is causally dependent on a distinct measured value existing (not just: there was an electron so it prints "I measured it.") 

(2) the measurement must be quantum erased. 

I think this is impossible because (1) depends on the measurement, being either LEFT or RIGHT and that specific distinct value being amplified to a classical variable "A measurement was made" which is embodied into the text of the document.  It can't be the exclusive OR of the L or R variables that is amplified, because that would always be true and would just be the equivalent of printing "I measured it." every time.  But if the distinct variable is amplified to a classical value, a print command,  it can't be quantum erased.

For comparison look at the Buckyball twin slit experiment.  The interference pattern disappears as the Buckyball radiation becomes sufficient in principle to locate it, even though the radiation just gets absorbed in the lab wall somewhere and statistically cannot be use to know where the Buckyball went.

Brent

On 10/27/2022 5:10 AM, John Clark wrote:

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[John Clark]

On Fri, Oct 28, 2022 at 1:09 AM Brent Meeker <meeke...@gmail.com> wrote:

> I was citing Carroll on the delayed choice quantum erasure...not on anything Deutsch said. 

OK, then whatever Carroll was saying that you were referring to is irrelevant to what we were discussing. And by the way, Carroll is just as big an advocate of the Many World's idea as Deutsch is and wrote an excellent book about that very subject.

> The problem I see in this is that the computer must make a measurement that does two things

1) it prints out a document that is causally dependent on a distinct measured value existing (not just: there was an electron so it prints "I measured it.") 

Yes, when the computer writes the document, writes it after the electron passes through the slits but before it hits the photographic plate, the machine knows which slit the electron went through but it reframes from including that bit information in the document, it retains that bit of information safely in its quantum memory and doesn't quantum erase it until a nanosecond before the electron hits the photographic plate.

 

> (2) the measurement must be quantum erased. 
I think this is impossible because (1) depends on the measurement, being either LEFT or RIGHT

No, the document is EXACTLY the same in both universes, that's why I kept emphasizing that it does not contain any information about which slot the electron went through, it just tells us if it was able to successfully make such a measurement and if it knows which slot the electron went through. So the only thing different about the two universes is the computer's memory about which slot the electron went through and if, unlike classical computers, that bit of information is stored quantum mechanically, then that bit of information can be erased quantum mechanically. At that point the two universes are identical again, that is to say they would have exactly the same quantum wave function, so it would be silly to pretend there are still two distinct universes.  

 

> and that specific distinct value being amplified to a classical variable

That's what usually happens and the amplification typically happens at enormous speed, that's why making any quantum experiment is difficult and making a quantum computer is even more difficult, but that's just an engineering difficulty caused by our limited technology, it is not a limitation imposed by scientific fundamentals. I'm talking about heroic engineering not impossible engineering, like a faster than light rocket or a perpetual motion machine.

 > if the distinct variable is amplified to a classical value, a print command,  it can't be quantum erased.

It makes no difference if the electron went left or right, the EXACT same print command is issued in both universes in either case, and that results in the EXACT same document being printed in both universes. I agree that if you let the distinct knowledge of which slit the electron went through get amplified and spread into the classical realm then it's game over, you're never gonna be able to erase all of that, so you're going to have to arrange things so that doesn't happen, or at least delay it from happening for long enough to complete the experiment. To do all this would be very difficult but it would not be impossible.  

   John K Clark    See what's on my new list at  Extropolis

7vv

 

[smitra]

On 26-10-2022 01:40, Bruce Kellett wrote:
> On Wed, Oct 26, 2022 at 10:15 AM smitra <smi...@zonnet.nl> wrote:
>
>> On 26-10-2022 00:14, Bruce Kellett wrote:
>>
>> There is no such thing as irreversible decoherence in unitary QM.
>> Now,
>> you and Brent have invoked the expansion of the universe in past
>> discussions to argue that fundamentally irreversible phenomena do
>> exist.
>> However this reasoning is flawed, because you then assume a
>> semi-classical model where the expansion of the universe is
>> described in
>> a classical way. If QM is fundamental, then the entire state of the
>> universe, including the space-time geometry is part of that quantum
>> description. You then have a wavefunctional that assigns a complex
>> amplitude to the entire state of the universe that includes al the
>> fields of all particles and also the space-time geometry.
>>
>> Thing is that the laws of physics are what they are. You cannot
>> demand
>> that you require measurement results to be truly permanent and that
>> they
>> therefore arise due to irreversible processes. Whether that's the
>> case
>> or not is determined by the laws of physics, not by us.
>
> The laws of physics tell us that measurements are irreversible.
> Unitary evolution is universal only in your imagination. Many Worlds
> is an interpretation, not an established fact.
>
> Bruce

The laws of physics as we know them today, rule out the existence of any
physical process that is fundamentally irreversible. So, measurements
cannot be irreversible if the known laws of physics are correct. If you
disagree then it's up to you to point to just a single example of such a
process and write up an article that proves your point and get that
published in a per reviewed journal.

Simply saying that QM as traditionally formulated considers measurement
as a special process that os irreversible, doesn't cut it, because
measurement is then not treated in terms of the fundamental dynamics of
the theory, it is put in in an ad hoc way.

Saibal

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[smitra]

On 26-10-2022 07:45, Brent Meeker wrote:

> On 10/25/2022 4:15 PM, smitra wrote:
>> On 26-10-2022 00:14, Bruce Kellett wrote:

>>> On Wed, Oct 26, 2022 at 9:00 AM John Clark <johnk...@gmail.com>
>>> wrote:
>>>
>>>> On Tue, Oct 25, 2022 at 5:31 PM Bruce Kellett
>>>> <bhkel...@gmail.com> wrote:
>>>>
>>>>> _> One of the main troubles with this is that the Copenhagen
>>>>> Interpretation, insofar as there is any such thing, does not
>>>>> entail that the wave function collapses when the result enters
>>>>> consciousness. This was a mad idea put forward by Wigner, and it
>>>>> was soon realized that the idea was just silly, and could never
>>>>> work. So that idea has long been abandoned. Deutsch's attempted
>>>>> proof involves comparison with an abandoned idea of quantum
>>>>> mechanics, so it doesn't really prove anything. Besides, the whole
>>>>> set-up involves assumptions about quantum computers and
>>>>> consciousness that are far from obvious, and probably not even
>>>>> correct._
>>>>
>>>> OK, so forget about consciousness, the fact remains that If you see
>>>> interference bands on Deutsch's photographic plate then that would
>>>> prove a universe can split and, provided the difference between them
>>>> is very small, can under the right conditions become identical again
>>>> and thus merge back together. That is the key part of the multiverse
>>>> idea and if it's true then there is no need to indulge in the
>>>> mumbo-jumbo of Copenhagen quantum complementarity.
>>>
>>> That is as much mumbo-jumbo as anything in Copenhagen. For instance,
>>> what determines if the difference between the worlds is small
>>> 'enough'? You are using the result of no divergence between worlds to
>>> conclude something about a divergence that probably never occurred.
>>> It
>>> is simpler to state that no measurement was made in the Deutsch
>>> set-up. Measurement, after all, involves irreversible decoherence,
>>> and
>>> such cannot be 'quantum erased'. So no which-way measurement would
>>> have been made in the Deutsch experiment. "Measurement" requires the
>>> formation of permanent records in the environment (and many copies of
>>> the result can be formed as well).

>>>
>>
>> There is no such thing as irreversible decoherence in unitary QM. Now,
>> you and Brent have invoked the expansion of the universe in past
>> discussions to argue that fundamentally irreversible phenomena do
>> exist. However this reasoning is flawed, because you then assume a
>> semi-classical model where the expansion of the universe is described
>> in a classical way. If QM is fundamental, then the entire state of the
>> universe, including the space-time geometry is part of that quantum
>> description. You then have a wavefunctional that assigns a complex
>> amplitude to the entire state of the universe that includes al the
>> fields of all particles and also the space-time geometry.
>

> That assumes that the long sought quantum theory of gravity will not
> break unitarity.  There are already proposals for this
> https://arxiv.org/pdf/2201.11658.pdf
>
> Brent

It's not clear that generalizing from unitary to isometric transforms
makes much of a difference here for the purpose of getting to a real
collapse of the wavefunction. ALso, in the article they

>>
>>
>> Thing is that the laws of physics are what they are. You cannot demand
>> that you require measurement results to be truly permanent and that
>> they therefore arise due to irreversible processes. Whether that's the
>> case or not is determined by the laws of physics, not by us.

Also, in the article they threat the space-time geometry as a classical
background field, the consider the problem of QFT in an expanding
universe. It's not clear at all from their proposals how in their
proposal where the dimension of Hilbert space increases, one would
quantize gravity.

Saibal

[Brent Meeker]

On 10/28/2022 4:33 AM, John Clark wrote:

On Fri, Oct 28, 2022 at 1:09 AM Brent Meeker <meeke...@gmail.com> wrote:

> I was citing Carroll on the delayed choice quantum erasure...not on anything Deutsch said. 

OK, then whatever Carroll was saying that you were referring to is irrelevant to what we were discussing. And by the way, Carroll is just as big an advocate of the Many World's idea as Deutsch is and wrote an excellent book about that very subject.

> The problem I see in this is that the computer must make a measurement that does two things
1) it prints out a document that is causally dependent on a distinct measured value existing (not just: there was an electron so it prints "I measured it.") 

Yes, when the computer writes the document, writes it after the electron passes through the slits but before it hits the photographic plate, the machine knows which slit the electron went through but it reframes from including that bit information in the document, it retains that bit of information safely in its quantum memory and doesn't quantum erase it until a nanosecond before the electron hits the photographic plate.

 

> (2) the measurement must be quantum erased. 
I think this is impossible because (1) depends on the measurement, being either LEFT or RIGHT

No, the document is EXACTLY the same in both universes,

I know that.  But it must be causally connected (entangled with) the measurement value of either L xor R.  It can't just be causally connected with L or R, because that's the printer that just says, "I measured it." whatever the value.

that's why I kept emphasizing that it does not contain any information about which slot the electron went through, it just tells us if it was able to successfully make such a measurement and if it knows which slot the electron went through. So the only thing different about the two universes is the computer's memory about which slot the electron went through and if, unlike classical computers, that bit of information is stored quantum mechanically, then that bit of information can be erased quantum mechanically. At that point the two universes are identical again, that is to say they would have exactly the same quantum wave function, so it would be silly to pretend there are still two distinct universes.  

 

> and that specific distinct value being amplified to a classical variable

That's what usually happens and the amplification typically happens at enormous speed, that's why making any quantum experiment is difficult and making a quantum computer is even more difficult, but that's just an engineering difficulty caused by our limited technology, it is not a limitation imposed by scientific fundamentals. I'm talking about heroic engineering not impossible engineering, like a faster than light rocket or a perpetual motion machine.

Well, I think your condition that it be erased before the particle hits the screen is another misunderstanding your part.  But it's not relevant to what I'm questioning because in principle you can have the detector screen a lightyear away.

 > if the distinct variable is amplified to a classical value, a print command,  it can't be quantum erased.

It makes no difference if the electron went left or right, the EXACT same print command is issued in both universes in either case, and that results in the EXACT same document being printed in both universes. I agree that if you let the distinct knowledge of which slit the electron went through get amplified and spread into the classical realm then it's game over,

But how else is the computer going to "truthfully" report that a measurement was made, i.e. a report that is entangled with either a measurement of L xor with a measurement of R?  I think this is impossible.  I'd like to the causal chain from a measurement of L that avoids amplifying that into decoherence.  In Carroll's exposition he considers measuring the L in the Up/Dwn direction, which you might consider amplifying to trigger the printer.  But then he shows that this doesn't actually erase the interference, it is just hidden:

============================================

When we measured the recording spin in the vertical direction, the result we obtained was entangled with a definite path for the traveling electron: [↑] was entangled with (L), and [↓] was entangled with (R). So by performing that measurement, we knew that the electron had traveled through one slit or the other. But now when we measure the recording spin along the horizontal axis, that’s no longer true. After we do each measurement, we are again in a branch of the wave function where the traveling electron passes through both slits. If we measured spin-left, the traveling electron passing through the right slit picks up a minus sign in its contribution to the wave function, but that’s just math.

By choosing to do our measurement in this way, we have erased the information about which slit the electron went through. This is therefore known as a “quantum eraser experiment.” This erasure doesn’t affect the overall distribution of flashes on the detector screen. It remains smooth and interference-free.

But we not only have the overall distribution of electrons hitting the detector screen; for each impact we know whether the recording electron was measured as spin-left or spin- right. So, instructs our professor with a flourish, let’s go to our computers and separate the flashes on the detector screen into these two groups — those that are associated with spin- left recording electrons, and those that are associated with spin-right. What do we see now?

Interestingly, the interference pattern reappears. The traveling electrons associated with spin-left recording electrons form an interference pattern, as do the ones associated with spin-right. (Remember that we don’t see the pattern all at once, it appears gradually as we detect many individual flashes.) But the two interference patterns are slightly shifted from each other, so that the peaks in one match up with the valleys in the other. There was secretly interference hidden in what initially looked like a featureless smudge.

==========================================

Brent

you're never gonna be able to erase all of that, so you're going to have to arrange things so that doesn't happen, or at least delay it from happening for long enough to complete the experiment. To do all this would be very difficult but it would not be impossible.  

   John K Clark    See what's on my new list at  Extropolis

7vv

 

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[Brent Meeker]

What does that mean for radiation to infinity?  Do you just rule it out
as "not fundamental"  since it depends on a boundary condition at
infinity?  Yet it is still physics and universal.

Brent

[Bruce Kellett]

On Sat, Oct 29, 2022 at 3:16 AM smitra <smi...@zonnet.nl> wrote:

On 26-10-2022 01:40, Bruce Kellett wrote:

> The laws of physics tell us that measurements are irreversible.
> Unitary evolution is universal only in your imagination. Many Worlds
> is an interpretation, not an established fact.
>
> Bruce

The laws of physics as we know them today, rule out the existence of any
physical process that is fundamentally irreversible. So, measurements
cannot be irreversible if the known laws of physics are correct.

But we know for a fact that the laws of physics as we know them today are not correct.

If you
disagree then it's up to you to point to just a single example of such a
process and write up an article that proves your point and get that
published in a per reviewed journal.

Quantum field theory does not include gravitation. I don't have to write a paper about

this because many people have already done so.

Simply saying that QM as traditionally formulated considers measurement
as a special process that os irreversible, doesn't cut it, because
measurement is then not treated in terms of the fundamental  dynamics of
the theory, it is put in in an ad hoc way.

Lots of things are put into physics in an ad hoc way. The Born rule is a prime example -- it is just

imposed on the quantum wave function in an ad hoc way -- it cannot be derived from the fundamental theory.

Bruce

[Brent Meeker]

But by Gleason's theorem it's the only consistent way to put a probability measure on Hilbert space.

Brent

Bruce

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[Bruce Kellett]

On Sat, Oct 29, 2022 at 10:27 AM Brent Meeker <meeke...@gmail.com> wrote:

On 10/28/2022 3:06 PM, Bruce Kellett wrote:

Simply saying that QM as traditionally formulated considers measurement
as a special process that os irreversible, doesn't cut it, because
measurement is then not treated in terms of the fundamental  dynamics of
the theory, it is put in in an ad hoc way.

Lots of things are put into physics in an ad hoc way. The Born rule is a prime example -- it is just

imposed on the quantum wave function in an ad hoc way -- it cannot be derived from the fundamental theory.

But by Gleason's theorem it's the only consistent way to put a probability measure on Hilbert space.

Who said we need a probability measure? That is as ad hoc as anything else; besides, unitary QM does not allow for a probabilistic interpretation.

Bruce

[Brent Meeker]

On 10/28/2022 4:38 PM, Bruce Kellett wrote:

On Sat, Oct 29, 2022 at 10:27 AM Brent Meeker <meeke...@gmail.com> wrote:

On 10/28/2022 3:06 PM, Bruce Kellett wrote:

Simply saying that QM as traditionally formulated considers measurement
as a special process that os irreversible, doesn't cut it, because
measurement is then not treated in terms of the fundamental  dynamics of
the theory, it is put in in an ad hoc way.

Lots of things are put into physics in an ad hoc way. The Born rule is a prime example -- it is just

imposed on the quantum wave function in an ad hoc way -- it cannot be derived from the fundamental theory.

But by Gleason's theorem it's the only consistent way to put a probability measure on Hilbert space.

Who said we need a probability measure?

Because we observe that the same initial condition results in different later conditions, but with predictable probability distributions.

That is as ad hoc as anything else; besides, unitary QM does not allow for a probabilistic interpretation.

Not if you insist that all evolution is unitary, but that's why Born added the projection postulate to connect the unitary evolution to observation.


Brent

Bruce

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[Bruce Kellett]

On Sat, Oct 29, 2022 at 10:54 AM Brent Meeker <meeke...@gmail.com> wrote:

On 10/28/2022 4:38 PM, Bruce Kellett wrote:

On Sat, Oct 29, 2022 at 10:27 AM Brent Meeker <meeke...@gmail.com> wrote:

On 10/28/2022 3:06 PM, Bruce Kellett wrote:

Simply saying that QM as traditionally formulated considers measurement
as a special process that os irreversible, doesn't cut it, because
measurement is then not treated in terms of the fundamental  dynamics of
the theory, it is put in in an ad hoc way.

Lots of things are put into physics in an ad hoc way. The Born rule is a prime example -- it is just

imposed on the quantum wave function in an ad hoc way -- it cannot be derived from the fundamental theory.

But by Gleason's theorem it's the only consistent way to put a probability measure on Hilbert space.

Who said we need a probability measure?

Because we observe that the same initial condition results in different later conditions, but with predictable probability distributions.

That is what is known as an ad hoc adjustment of the theory --  anything that is required for the theory to agree with observation. Let's face it, all of physics is ad hoc!

That is as ad hoc as anything else; besides, unitary QM does not allow for a probabilistic interpretation.

Not if you insist that all evolution is unitary, but that's why Born added the projection postulate to connect the unitary evolution to observation.

But Saibal and his ilk are insisting that all physics is unitary. That is why the addition of probability (and the Born Rule) is just an ad hoc adjustment so that their theory agrees with observation. Gleason's theorem does not change this fact.

Bruce

[Brent Meeker]

It's not "ad hoc" when it's part of a theory that applies to everything.  Without the projection postulate and the probability interpretation how would we compare QM to experimental data?

Brent

[Bruce Kellett]

That is just an arbitrary stipulation.

Without the projection postulate and the probability interpretation how would we compare QM to experimental data?

We couldn't, so we would have to conclude that the theory was useless. That is why we add ad hoc postulates.....to compare to experiment.

Bruce

[Brent Meeker]

On 10/28/2022 5:43 PM, Bruce Kellett wrote:

On Sat, Oct 29, 2022 at 11:37 AM Brent Meeker <meeke...@gmail.com> wrote:

On 10/28/2022 5:28 PM, Bruce Kellett wrote:

On Sat, Oct 29, 2022 at 10:54 AM Brent Meeker <meeke...@gmail.com> wrote:

On 10/28/2022 4:38 PM, Bruce Kellett wrote:

On Sat, Oct 29, 2022 at 10:27 AM Brent Meeker <meeke...@gmail.com> wrote:

On 10/28/2022 3:06 PM, Bruce Kellett wrote:

Simply saying that QM as traditionally formulated considers measurement
as a special process that os irreversible, doesn't cut it, because
measurement is then not treated in terms of the fundamental  dynamics of
the theory, it is put in in an ad hoc way.

Lots of things are put into physics in an ad hoc way. The Born rule is a prime example -- it is just

imposed on the quantum wave function in an ad hoc way -- it cannot be derived from the fundamental theory.

But by Gleason's theorem it's the only consistent way to put a probability measure on Hilbert space.

Who said we need a probability measure?

Because we observe that the same initial condition results in different later conditions, but with predictable probability distributions.

That is what is known as an ad hoc adjustment of the theory --  anything that is required for the theory to agree with observation. Let's face it, all of physics is ad hoc!

That is as ad hoc as anything else; besides, unitary QM does not allow for a probabilistic interpretation.

Not if you insist that all evolution is unitary, but that's why Born added the projection postulate to connect the unitary evolution to observation.

But Saibal and his ilk are insisting that all physics is unitary. That is why the addition of probability (and the Born Rule) is just an ad hoc adjustment so that their theory agrees with observation. Gleason's theorem does not change this fact.

It's not "ad hoc" when it's part of a theory that applies to everything.

That is just an arbitrary stipulation.

ad hoc

ăd hŏk′, hōk′

adverb

1. For the specific purpose, case, or situation at hand and for no other.
2. On the spur of the moment.
3. For a particular purpose.

Brent

Without the projection postulate and the probability interpretation how would we compare QM to experimental data?

We couldn't, so we would have to conclude that the theory was useless. That is why we add ad hoc postulates.....to compare to experiment.

Bruce

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[Bruce Kellett]

For the particular purpose of relating the theory to observation, it is certainly ad hoc.

Look, "ad hoc" is frequently bandied about as a fatal flaw in any theory. Just as Putin waves about the nuclear threat: this is just to intimidate the opposition, it doesn't mean anything more. Any theory has ad hoc elements, or else it would not be of any value in explaining our experience. There is always a theoretical part, and then a collection of elements that serve to relate the theory to observation. Everything is ultimately ad hoc, because it is for the particular purpose of explaining observation.

Bruce

[Brent Meeker]

That's pretty damned broad reading of "particular".

Look, "ad hoc" is frequently bandied about as a fatal flaw in any theory. Just as Putin waves about the nuclear threat: this is just to intimidate the opposition, it doesn't mean anything more. Any theory has ad hoc elements, or else it would not be of any value in explaining our experience. There is always a theoretical part, and then a collection of elements that serve to relate the theory to observation. Everything is ultimately ad hoc, because it is for the particular purpose of explaining observation.

I think you've stretched it's meaning beyond recognition.  If every theory that is devised to match experiment is ad hoc then indeed all science is ad hoc...and the better for it.  But there is real ad hockery that is deserving of criticism.

The real question on the table is what would you take to be not ad hoc; what would be better than "... measurement is then not treated in terms of the fundamental  dynamics of the theory."  Do you see MWI doing this?

Brent

[Bruce Kellett]

No. MWI takes unitary dynamics of the Schrodinger equation to be fundamental. But unitary dynamics and the SE are deterministic, and incompatible with a probabilistic interpretation. So MWI is not going to be able to give a completely satisfactory account of measurement since the outcomes of measurement are inherently probabilistic. So whatever you do in MWI, measurement is not treated in terms of the fundamental dynamics of the theory; there is always some ad hoc element required to make contact with experiment. In that context MWI, is simply engaging in a double standard when it criticizes collapse theories as ad hoc.

Bruce

[Brent Meeker]

I agree with that, since I think collapse or probability is necessary for the theory to work.  But I regard it all as one unified theory.  As Omnes writes, "QM is a probabilistic theory.  So it predicts probabilities."

Brent

[Bruce Kellett]

On Sat, Oct 29, 2022 at 3:21 PM Brent Meeker <meeke...@gmail.com> wrote:

I agree with that, since I think collapse or probability is necessary for the theory to work.  But I regard it all as one unified theory.  As Omnes writes, "QM is a probabilistic theory.  So it predicts probabilities."

The problem is that MWI is not a probabilistic theory, so it can't be all of QM.

Bruce

[John Clark]

On Fri, Oct 28, 2022 at 6:07 PM Bruce Kellett <bhkel...@gmail.com> wrote:

> But we know for a fact that the laws of physics as we know them today are not correct.

True, the laws of physics as we know them break down at the centers of Black Holes and at the instant of the Big Bang, but they're the best thing we have right now and they seem to insist very strongly that many worlds do exist. And there is absolutely no reason to think that when we find them the new improved laws of physics will rule out many worlds rather than provide even more evidence that they exist.

> Lots of things are put into physics in an ad hoc way. The Born rule is a prime example -- it is just

imposed on the quantum wave function in an ad hoc way -- it cannot be derived from the fundamental theory.

You've got it backwards. The Born Rule does NOT need theory to justify itself, instead theory needs The Born Rule to justify itself because we know from experiment that The Born Rule is correct. If there is a conflict between The Born Rule and theory then The Born Rule wins and the theory must be discarded.

 > Who said we need a probability measure?

Experiment is the one that says we need a probability measure when we get into the quantum realm, and in science, theory must always take a backseat. Experiment and observation is always the boss, theory never is.

John K Clark    See what's on my new list at  Extropolis

eib

myh

 

[Lawrence Crowell]

Why is MWI not probabilistic? It is an interpretation of quantum amplitudes. It states that in a decoherence event the paths for particular probabilities, say the diagonal of the density matrix, are "globally" a part of a superposed or entangled set, but that "locally" only one outcome occurs and so the world splits. I am not sure why this violates probability. Decoherence attenuates the off diagonal quantum phase terms of the density matrix, and a density matrix reduced to diagonal form means that at this point the collapse is a sort of "classical collapse." One possible objection to MWI might be how can a classical outcome of probabilities then have this splitting off of quantum worlds? There is a funny meaning to the world as nonlocal in some bird's eye perspective, but local from the frog's eye perspective, where the frog perceives itself as "quantum frame dragged" along a particular quantum path.

MWI plays with nonlocality in a strange way. The splitting of worlds, say Alice and Bob looking at their Stern-Gerlach apparatus. We have the Einstein glove issue if Alice and Bob both measure in the z-direction. However, if Alice measures along the z-axis and then Bob measures along the x axis, or somewhere in the x-z plane, these two measurements are independent. Alice's measurement has no dependency on what Bob's measurement is, Bell's inequality violation, and Bob must measure independently. Yet, MWI has a global splitting of worlds, and here we see the outcome is not reduced by a local measurement. MWI has this added feature of nonlocal property with how worlds split apart.

LC

[Lawrence Crowell]

Quantum mechanics deals with the evolution of probability amplitudes a_i and probabilities are p_i = |a_i|^2. The probabilities are the trace of the density matrix and the density matrix by the Schrodinger equation is  dρ/dt = [H, ρ], and this describes the evolution of probabilities. With an actual outcome the probabilities are no longer applicable due to there being only one outcome. 

LC

[Brent Meeker]

Art Hobson has a series of papers on the "measurement problem" in which he argues that past analyses, by von Neumann and others, incorrectly ignore non-local entanglement in going from the density matrix of the system+instrument to the diagonalized system+instrument representing a mixture.  And when this is correctly accounted for he says the non-local entanglement causes the measured value (which is random per Born) to be a unique realization of the eigenvector...no multiple worlds. 

SUMMARY AND CONCLUSION
Using only the standard principles of quantum physics, but minus the
collapse postulate, we have shown that quantum state collapse occurs as a
consequence of the entanglement that occurs upon measurement as described in
1932 by von Neumann (Equation (4)). The entangled "measurement state" of a
quantum system and its detector is the collapsed state: It incorporates the required
perfect correlations between the system and its detector, it predicts precisely one
definite outcome, and it incorporates the nonlocal properties--the instantaneous
collapse across all branches of the superposition--that Einstein showed to be
required in quantum measurements

See attached.

Brent

[Lawrence Crowell]

I remember some issue surrounding this. I do not remember the way it was resolved, but I do recall that Hobson was considered wrong.

LC

[Brent Meeker]

Thanks.  I found this critique by Kastner (who of course says that the transactional interpretation solves the problem).

https://arxiv.org/ftp/arxiv/papers/1308/1308.4272.pdf

Brent

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[Lawrence Crowell]

Interesting that TI might show this. Q-interpretations can have their utility.

LC