Bell's Inequality and Many Worlds ( Was: The Nature of Contingency)

[John Clark]

On Thu, Mar 3, 2022 at 7:03 PM Bruce Kellett <bhkel...@gmail.com> wrote:

>> Just exchange the 2 slits in the experiments that I described with a polarizer and then the world would split because of polarization differences not because of which slip the photon went through, or if you prefer exchange the photons with electrons and the 2 slits with a Stern-Gerlach magnet, and then the world will split because of differences in spin of the electron; after that everything I said was still hold true, and nowhere would there be a need to invoke non-local influences. And you can build any Bell-type experiment you like with polarization or with spin,

> Yes. But you have to show how non-separable states can exhibit locality. Or, at least, you are required to show in detail how the correlation arise locally, in many worlds, or in any other theory.

Well OK but.... if you want all the details this is going to be a long post, you asked for it. First I'm gonna have to show that any theory (except for superdeterminism which is idiotic) that is deterministic, local and realistic cannot possibly explain the violation of Bell's Inequality that we see in our experiments, and then show why a theory like Many Worlds witch is deterministic and local but NOT realistic can.

The hidden variable concept was Einstein's idea, he thought there was a local reason all events happened, even quantum mechanical events, but we just can't see what they are. It was a reasonable guess at the time but today experiments have shown that Einstein was wrong, to do that I'm gonna illustrate some of the details of Bell's inequality with an example.

When a photon of undetermined polarization hits a polarizing filter there is a 50% chance it will make it through. For many years physicists like Einstein who disliked the idea that God played dice with the universe figured there must be a hidden variable inside the photon that told it what to do. By "hidden variable" they meant something different about that particular photon that we just don't know about. They meant something equivalent to a look-up table inside the photon that for one reason or another we are unable to access but the photon can when it wants to know if it should go through a filter or be stopped by one. We now understand that is impossible. In 1964 (but not published until 1967) John Bell showed that correlations that work by hidden variables must be less than or equal to a certain value, this is called Bell's inequality. In experiment it was found that some correlations are actually greater than that value. Quantum Mechanics can explain this, classical physics or even classical logic can not.

Even if Quantum Mechanics is someday proven to be untrue Bell's argument is still valid, in fact his original paper had no Quantum Mechanics in it and can be derived with high school algebra; his point was that any successful theory about how the world works must explain why his inequality is violated, and today we know for a fact from experiments that it is indeed violated. Nature just refuses to be sensible and doesn't work the way you'd think it should.            

I have a black box, it has a red light and a blue light on it, it also has a rotary switch with 6 connections at the 12,2,4,6,8 and 10 o'clock positions. The red and blue light blink in a manner that passes all known tests for being completely random, this is true regardless of what position the rotary switch is in. Such a box could be made and still be completely deterministic by just pre-computing 6 different random sequences and recording them as a look-up table in the box. Now the box would know which light to flash.

I have another black box. When both boxes have the same setting on their rotary switch they both produce the same random sequence of light flashes. This would also be easy to reproduce in a classical physics world, just record the same 6 random sequences in both boxes. 

The set of boxes has another property, if the switches on the 2 boxes are set to opposite positions, 12 and 6 o'clock for example, there is a total negative correlation; when one flashes red the other box flashes blue and when one box flashes blue the other flashes red. This just makes it all the easier to make the boxes because now you only need to pre-calculate 3 random sequences, then just change every 1 to 0 and every 0 to 1 to get the other 3 sequences and record all 6 in both boxes.

The boxes have one more feature that makes things very interesting, if the rotary switch on a box is one notch different from the setting on the other box then the sequence of light flashes will on average be different 1 time in 4. How on Earth could I make the boxes behave like that? Well, I could change on average one entry in 4 of the 12 o'clock look-up table (hidden variable) sequence and make that the 2 o'clock table. Then change 1 in 4 of the 2 o'clock and make that the 4 o'clock, and change 1 in 4 of the 4 o'clock and make that the 6 o'clock. So now the light flashes on the box set at 2 o'clock is different from the box set at 12 o'clock on average by 1 flash in 4. The box set at 4 o'clock differs from the one set at 12 by 2 flashes in 4, and the one set at 6 differs from the one set at 12 by 3 flashes in 4.

BUT I said before that boxes with opposite settings should have a 100% anti-correlation, the flashes on the box set at 12 o'clock should differ from the box set at 6 o'clock by 4 flashes in 4 NOT 3 flashes in 4. Thus if the boxes work by hidden variables then when one is set to 12 o'clock and the other to 2 there MUST be a 2/3 correlation, at 4 a 1/3 correlation, and of course at 6 no correlation at all.  A correlation greater than 2/3, such as 3/4, for adjacent settings produces paradoxes, at least it would if you expected everything to work mechanistically because of some local hidden variable involved.

Does this mean it's impossible to make two boxes that have those specifications? Nope, but it does mean hidden variables can not be involved and that means something very weird is going on. Actually it would be quite easy to make a couple of boxes that behave like that, it's just not easy to understand how that could be. 

Photons behave in just this spooky manner, so to make the boxes all you need it 4 things:

1) A glorified light bulb, something that will make two photons of unspecified but identical polarizations moving in opposite directions so you can send one to each box. An excited calcium atom would do the trick, or you could turn a green photon into two identical lower energy red photons with a crystal of potassium dihydrogen phosphate.

2) A light detector sensitive enough to observe just one photon. Incidentally the human eye is not quite good enough to do that but frogs can, for frogs when light gets very weak it must stop getting dimmer and appear to flash instead. 

3) A polarizing filter, we've had these for well over a century.

4) Some gears and pulleys so that each time the rotary switch is advanced one position the filter is advanced by 30 degrees. This is because it's been known for many years that the amount of light polarized at 0 degrees that will make it through a polarizing filter set at X is [COS (x)]^2; and if X = 30 DEGREES (π/6 radians) then the value is .75; if the light is so dim that only one photon is sent at a time then that translates to the probability that any individual photon will make it through the filter is 75%.

The bottom line of all this is that there can not be something special about a specific photon, some internal difference, some hidden local variable that determines if it makes it through a filter or not. Thus if we ignore a superdeterministic conspiracy, as we should, then one of two things MUST be true:

1) the universe is not realistic, that is, things do NOT exist in one and only one state both before and after they are observed. In the case of Many Worlds it means the very look up table as described in the above cannot be printed in indelible ink but, because Many Worlds assumes that Schrodinger's Equation means what it says, the look up table itself not only can but must exist in many different versions both before and after a measurement is made.

2) The universe is non-local, that is, everything influences everything else and does so without regard for the distances involved or amount of time involved or even if the events happen in the past or the future; the future could influence the past. But because Many Worlds is non-realistic, and thus doesn't have a static lookup table, it has no need to resort to any of these non-local influences to explain experimental results.

Einstein liked non-locality even less than nondeterminism, I'm not sure how he'd feel about non-realistic theories like Many Worlds, the idea wasn't discovered until about 10 years after his death.  

 >> for these purposes the words "world" and "universe" are interchangeable and have exactly the same meaning they have when used in any other context. I meant nothing new or exotic in the words.

> Worlds are disjoint and do not interact.

There's no reason they can't be if the difference between the worlds is tiny because they've only been separated for a tiny amount of time.  If the difference between the worlds is very very small it's not statistically improbable that they could evolve into the same state and thus merge, but if the difference is large it becomes ridiculously improbable for that to happen.

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

bim

 

[Bruce Kellett]

On Sat, Mar 5, 2022 at 2:50 AM John Clark <johnk...@gmail.com> wrote:

On Thu, Mar 3, 2022 at 7:03 PM Bruce Kellett <bhkel...@gmail.com> wrote:

>> Just exchange the 2 slits in the experiments that I described with a polarizer and then the world would split because of polarization differences not because of which slip the photon went through, or if you prefer exchange the photons with electrons and the 2 slits with a Stern-Gerlach magnet, and then the world will split because of differences in spin of the electron; after that everything I said was still hold true, and nowhere would there be a need to invoke non-local influences. And you can build any Bell-type experiment you like with polarization or with spin,

> Yes. But you have to show how non-separable states can exhibit locality. Or, at least, you are required to show in detail how the correlation arise locally, in many worlds, or in any other theory.

Well OK but.... if you want all the details this is going to be a long post, you asked for it.

Yes, I asked for a detailed account of how MWI produces the correlations for  the entangled singlet state. The trouble is that you have not provided this. Your post is long and rambling, full of a lot of unnecessary detail, but the bottom line is the claim that since MWI is not realistic, it can be local. You have made that claim many times before, but the current post comes no nearer to giving a local explanation than any of your previous posts.

What is required is a local account, invoking many worlds as necessary, that can explain how the correlations are built up. In the usual Alice/Bob setup, when Alice measures her particle, she splits into two branches: in one of which she sees spin_up and in the other, spin_down. Similarly, Bob splits on his measurement into Bob_up and Bob_down branches. When Alice and Bob come together, each splits again according to which branch of the other they meet. So there are then four branches, up-up, up-down, down-up, and down-down for the results of Alice and Bob respectively. For all polarizer orientations apart from parallel or orthogonal, these four branches must exist. But for parallel or orthogonal polarizers only two branches are possible for an initial singlet state -- Alice and Bob must get opposite results, for parallel polarizers, and the same result for orthogonal polarizers. In other words the up-up and down-down branches do not exist for parallel polarizers. How is this magic achieved in many worlds?

Things are more complicated in the general case of polarizers at an arbitrary relative angle, theta. The question then is how do we manage the correlations between consecutive trials in order to preserve the cos^2(theta/2) probability. (Over a sequence of N trials, the proportion of up-down branches for polarizers at the relative angle theta must be approximately cos^2(theta/2)).

In a sequence of N trials, both Alice and Bob split into 2^N copies, each copy has a unique sequence of up and down results. When Alice and Bob meet, the usual MWI procedure means that there are (2^N)^(2^N) branches, as each of the 2^N branches for Alice meets the 2^N branches for Bob. Out of all these branches, only one has the matching sequence of up and down from each end required to get the correlations correct, How does MWI get rid of all the (2^N)^(2^N)-1 incorrect branches?

This is the question you are required to answer in detail,  without generalized fudging or appeals to magic.

Bruce

[John Clark]

On Fri, Mar 4, 2022 at 5:34 PM Bruce Kellett <bhkel...@gmail.com> wrote:

> What is required is a local account, invoking many worlds as necessary, that can explain how the correlations are built up. In the usual Alice/Bob setup, when Alice measures her particle, she splits into two branches: in one of which she sees spin_up and in the other, spin_down. Similarly, Bob splits on his measurement into Bob_up and Bob_down branches. When Alice and Bob come together, each splits again according to which branch of the other they meet. So there are then four branches, up-up, up-down, down-up, and down-down for the results of Alice and Bob respectively.

No! There are only two branches, if 2 electrons are entangled and Alice measures spin up then Bob will measure spin down with certainty. The outcome of the experiment can only be up-down or down-up, up-up and down-down NEVER happens. Many Worlds doesn't say everything can happen, it says everything that is consistent with Schrödinger's Equation will happen, but up-up and down-down are NOT consistent with Schrodinger. In the language of Many Worlds, the world splits into the up-down and down-up universes, there are no up-up or down-down universes.

> the current post comes no nearer to giving a local explanation than any of your previous posts.

I clearly showed that a violation of Bell's Inequality is not just physically impossible but is logically impossible IF things are both local and realistic, and I also clearly showed that Many Worlds can still work because although it is local it is not realistic, and because Many Worlds is non-realistic, and thus doesn't have a static lookup table, it has no need to resort to any of these non-local influences to explain experimental results. That is what you asked for and that is what I  provided, so I don't see why I should be required to write more, I already feel like I'm on the verge of carpal tunnel syndrome. 

 

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

xoc

[Bruce Kellett]

On Sat, Mar 5, 2022 at 10:23 AM John Clark <johnk...@gmail.com> wrote:

On Fri, Mar 4, 2022 at 5:34 PM Bruce Kellett <bhkel...@gmail.com> wrote:

> What is required is a local account, invoking many worlds as necessary, that can explain how the correlations are built up. In the usual Alice/Bob setup, when Alice measures her particle, she splits into two branches: in one of which she sees spin_up and in the other, spin_down. Similarly, Bob splits on his measurement into Bob_up and Bob_down branches. When Alice and Bob come together, each splits again according to which branch of the other they meet. So there are then four branches, up-up, up-down, down-up, and down-down for the results of Alice and Bob respectively.

No! There are only two branches, if 2 electrons are entangled and Alice measures spin up then Bob will measure spin down with certainty. The outcome of the experiment can only be up-down or down-up, up-up and down-down NEVER happens

That is what you are required to explain. The Schrodinger equation certainly allows, in fact, requires, all four branches to be present if the measurements Alice and Bob make are independent. Your task is to show why two of these branches are not present for measurements on entangled particles. Mere assertion is not sufficient.

Many Worlds doesn't say everything can happen, it says everything that is consistent with Schrödinger's Equation will happen, but up-up and down-down are NOT consistent with Schrodinger.

 

They are, in fact. You have to show why they do not occur for entangled particles but do occur for independent particles.

 

In the language of Many Worlds, the world splits into the up-down and down-up universes, there are no up-up or down-down universes.

> the current post comes no nearer to giving a local explanation than any of your previous posts.

I clearly showed that a violation of Bell's Inequality is not just physically impossible but is logically impossible IF things are both local and realistic, and I also clearly showed that Many Worlds can still work because although it is local it is not realistic, and because Many Worlds is non-realistic, and thus doesn't have a static lookup table, it has no need to resort to any of these non-local influences to explain experimental results.

That does not follow. Even if your dichotomy were true (which it is not) it does not prove that a theory which is local, but non-realistic, can explain the Bell correlations. That is the case for MWI, and you have not shown that it can provide a local explanation. Your logic is faulty.

Bruce

[John Clark]

On Fri, Mar 4, 2022 at 7:12 PM Bruce Kellett <bhkel...@gmail.com> wrote:

>>> What is required is a local account, invoking many worlds as necessary, that can explain how the correlations are built up. In the usual Alice/Bob setup, when Alice measures her particle, she splits into two branches: in one of which she sees spin_up and in the other, spin_down. Similarly, Bob splits on his measurement into Bob_up and Bob_down branches. When Alice and Bob come together, each splits again according to which branch of the other they meet. So there are then four branches, up-up, up-down, down-up, and down-down for the results of Alice and Bob respectively.

>>No! There are only two branches, if 2 electrons are entangled and Alice measures spin up then Bob will measure spin down with certainty. The outcome of the experiment can only be up-down or down-up, up-up and down-down NEVER happens

>That is what you are required to explain. The Schrodinger equation certainly allows, in fact, requires, all four branches to be present

BULLSHIT!

[Bruce Kellett]

That is a most eloquent refutation of everything you have ever said.

Bruce

[John Clark]

Just answer me 2 questions. 

1) If Schrodinger's equation not only allows but insists that conservation of spin be violated as you claim then why the hell did they give Schrödinger the Nobel prize for finding an equation that grossly violates experimental results.

2) Why the hell are physics students still required to study such a ridiculous useless equation that has no relation to physical reality?

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

lws

[Bruce Kellett]

On Sat, Mar 5, 2022 at 11:47 AM John Clark <johnk...@gmail.com> wrote:

On Fri, Mar 4, 2022 at 7:30 PM Bruce Kellett <bhkel...@gmail.com> wrote:

On Sat, Mar 5, 2022 at 11:17 AM John Clark <johnk...@gmail.com> wrote:

On Fri, Mar 4, 2022 at 7:12 PM Bruce Kellett <bhkel...@gmail.com> wrote:

>>> What is required is a local account, invoking many worlds as necessary, that can explain how the correlations are built up. In the usual Alice/Bob setup, when Alice measures her particle, she splits into two branches: in one of which she sees spin_up and in the other, spin_down. Similarly, Bob splits on his measurement into Bob_up and Bob_down branches. When Alice and Bob come together, each splits again according to which branch of the other they meet. So there are then four branches, up-up, up-down, down-up, and down-down for the results of Alice and Bob respectively.

>>No! There are only two branches, if 2 electrons are entangled and Alice measures spin up then Bob will measure spin down with certainty. The outcome of the experiment can only be up-down or down-up, up-up and down-down NEVER happens

>That is what you are required to explain. The Schrodinger equation certainly allows, in fact, requires, all four branches to be present

BULLSHIT!

> That is a most eloquent refutation of everything you have ever said.

 

Just answer me 2 questions. 

1) If Schrodinger's equation not only allows but insists that conservation of spin be violated as you claim

That is not the claim I made. I said "The Schrodinger equation certainly allows, in fact, requires, all four branches to be present if the measurements Alice and Bob make are independent." You dishonestly deleted the last part of this statement. If the measurements are independent, then the rules of MWI imply that all four branches are present when Alice and Bob meet. When the measurements are not independent, as when Alice and Bob measure a pair of entangled spin zero particles, then only two branches are present if the polarizers are parallel (but all four branches are present if the polarizers are not parallel). The question is, "Why is that? What makes the difference? And how is that explained locally in MWI?" You have not addressed any of the relevant questions.

then why the hell did they give Schrödinger the Nobel prize for finding an equation that grossly violates experimental results.

2) Why the hell are physics students still required to study such a ridiculous useless equation that has no relation to physical reality?

The Shrodinger equation is studied because it is useful. Bell type correlations of entangled particles are also studied because they show that quantum mechanics is intrinsically non local. MWI is just as non local as any other interpretation. No local explanation of the correlations is possible -- as your ramblings have demonstrated.

Bruce

[Brent Meeker]

On Sat, Mar 5, 2022 at 10:23 AM John Clark <johnk...@gmail.com> wrote:

Many Worlds doesn't say everything can happen, it says everything that is consistent with Schrödinger's Equation will happen, but up-up and down-down are NOT consistent with Schrodinger.

 

They don't occur because the particles are in an entangled state in which they have opposite spin, but no definite spin direction.  So the effect of measuring one is to determine the other, even at spacelike separation.  That's non-local.

Brent

[Bruce Kellett]

That's the explanation I have been probing for. So far, JC has failed to recognize the correctness of this.

Bruce

[John Clark]

On Fri, Mar 4, 2022 at 8:11 PM Bruce Kellett <bhkel...@gmail.com> wrote:

>> Just answer me 2 questions. 

1) If Schrodinger's equation not only allows but insists that conservation of spin be violated as you claim

> That is not the claim I made.

Like hell it wasn't!  What I said was  "The outcome of the experiment can only be up-down or down-up, up-up and down-down NEVER happens" you responded with "That is what you are required to explain. The Schrodinger equation certainly allows, in fact, requires, all four branches to be present". Now I know that anybody can have a brain fart, and if that's what it was I won't speak about it again, but don't tell me that wasn't the claim you made because that is bullshit.

 

> I said "The Schrodinger equation certainly allows, in fact, requires, all four branches to be present 

Yes, that's what you said. And if Schrodinger equation allowed ( or even demand according to you) that the conservation of spin be violated then no respectable physicist would touch Schrodinger's equation with a 10 foot pole. But of course it isn't true.   

> If the measurements Alice and Bob make are independent." You dishonestly deleted the last part of this statement. If the measurements are independent,

And that is more nonsense, if the particles are in entangled, as they must be if you wish to perform any Bell type experiment , then the particles can't be independent, because that's what entangled means 

> When the measurements are not independent, as when Alice and Bob measure a pair of entangled spin zero particles, then only two branches are present if the polarizers are parallel (but all four branches are present if the polarizers are not parallel).

So now you're claiming if the polarizers are not parallel then the law of conservation of spin is violated,  you're claiming that a zero spin particle could decay into 2 spin up particles,  and that is pure unadulterated extra-virgin bullshit.

 

> The question is, "Why is that? What makes the difference?

The difference is up-down and down-up are consistent with Schrodinger's equation and with the law of conservation of spin, but up-up and down-down is not. 

> The Shrodinger equation is studied because it is useful.

And if that equation demanded the law of conservation of spin be violated it would be utterly useless and Mr. Schrodinger would be a laughingstock and not a Nobel prize winner.

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

swq

 

[Bruce Kellett]

On Sat, Mar 5, 2022 at 12:54 PM John Clark <johnk...@gmail.com> wrote:

On Fri, Mar 4, 2022 at 8:11 PM Bruce Kellett <bhkel...@gmail.com> wrote:

>> Just answer me 2 questions. 

1) If Schrodinger's equation not only allows but insists that conservation of spin be violated as you claim

> That is not the claim I made.

Like hell it wasn't!  What I said was  "The outcome of the experiment can only be up-down or down-up, up-up and down-down NEVER happens" you responded with "That is what you are required to explain. The Schrodinger equation certainly allows, in fact, requires, all four branches to be present". Now I know that anybody can have a brain fart, and if that's what it was I won't speak about it again, but don't tell me that wasn't the claim you made because that is bullshit.

 

> I said "The Schrodinger equation certainly allows, in fact, requires, all four branches to be present 

Yes, that's what you said. And if Schrodinger equation allowed ( or even demand according to you) that the conservation of spin be violated then no respectable physicist would touch Schrodinger's equation with a 10 foot pole. But of course it isn't true.   

> If the measurements Alice and Bob make are independent." You dishonestly deleted the last part of this statement. If the measurements are independent,

And that is more nonsense, if the particles are in entangled, as they must be if you wish to perform any Bell type experiment , then the particles can't be independent, because that's what entangled means 

> When the measurements are not independent, as when Alice and Bob measure a pair of entangled spin zero particles, then only two branches are present if the polarizers are parallel (but all four branches are present if the polarizers are not parallel).

So now you're claiming if the polarizers are not parallel then the law of conservation of spin is violated,  you're claiming that a zero spin particle could decay into 2 spin up particles,  and that is pure unadulterated extra-virgin bullshit.

I think you need to brush up on some elementary quantum mechanics. If the polarizers are not parallel (at a relative angle theta) then the probability of an up-up result for Alice and Bob's measurements is given by sin^2(theta/2). Since up-up and down-down results are possible for non-aligned polarizers, all four branches are present in this general case. This does not involve a violation of angular momentum, and more than a z-spin up result from measuring a particle prepared with x-spin up violates angular momentum conservation.

Bruce

[Stathis Papaioannou]

Why can’t the correlation have occurred when the entangled particles were created? Measuring one particle pair then reveals which world the measurer is in, and therefore the state of the other pair, which is in the same world.

--

Stathis Papaioannou

[Bruce Kellett]

And how does that happen, other than non-locally? If the measurement of one particle reveals the state of the other of the pair, that can only be non-local since the other is at a spacelike separation. The correlations cannot be explained as for Bertlmann's socks..... for which seeing one sock reveals the colour of the other. That is not possible for entangled particles that give the observed correlations.

Bruce

[Brent Meeker]

Then which world, i.e. the spin orientation shared by the particles, is a hidden variable and would satisfy Bell's inequality.

Brent

[Stathis Papaioannou]

If the experimenters can choose to measure in a fundamentally random way.

--

Stathis Papaioannou

[John Clark]

On Fri, Mar 4, 2022 at 10:42 PM Bruce Kellett <bhkel...@gmail.com> wrote:

>> So now you're claiming if the polarizers are not parallel then the law of conservation of spin is violated,  you're claiming that a zero spin particle could decay into 2 spin up particles,  and that is pure unadulterated extra-virgin bullshit.

> I think you need to brush up on some elementary quantum mechanics. If the polarizers are not parallel (at a relative angle theta) then the probability of an up-up result for Alice and Bob's measurements is given by sin^2(theta/2).

And I said  that in my long post.  

> Since up-up and down-down results are possible for non-aligned polarizers,

NO, up-up and down-down is never allowed! If I set my polarizer in the "up" alignment (and I am free to pick any direction I like and call it "up") and a undetermined photon makes it through then then I know with 100% certainty that my photon is now polarized "up", and I know for a fact that if you set your polarizer to the corresponding "down" position then there is a 100% chance the brother photon that is entangled with mine will make it through your polarizer and a 0% probability it will not. Set the polarizers to any angle you like but you will NEVER ever ever see up-up or down-down.  

If instead of orienting your filter in the "down" position you only misaligne it from mine by 30° then is a 75% chance the photon will make it through your polarizer, if it does then you know with certainty that your photon is now, not in the "up" direction, but in a direction 30° from "up". And you know one other thing, you know that your photon and mine are no longer entangled because misaligned polarizers destroy entanglement.  By the way, I use quotation marks because "up" and "down" are completely arbitrary directions, as long as consistency is maintained between what is called "up" and "down" any direction can be chosen.  

> all four branches are present in this general case.

If that was true then the law of conservation of angular momentum would have to be false.  The law of conservation of angular momentum is not false.

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

6sm

[Lawrence Crowell]

On Friday, March 4, 2022 at 4:34:12 PM UTC-6 Bruce wrote:

On Sat, Mar 5, 2022 at 2:50 AM John Clark <johnk...@gmail.com> wrote:

On Thu, Mar 3, 2022 at 7:03 PM Bruce Kellett <bhkel...@gmail.com> wrote:

>> Just exchange the 2 slits in the experiments that I described with a polarizer and then the world would split because of polarization differences not because of which slip the photon went through, or if you prefer exchange the photons with electrons and the 2 slits with a Stern-Gerlach magnet, and then the world will split because of differences in spin of the electron; after that everything I said was still hold true, and nowhere would there be a need to invoke non-local influences. And you can build any Bell-type experiment you like with polarization or with spin,

> Yes. But you have to show how non-separable states can exhibit locality. Or, at least, you are required to show in detail how the correlation arise locally, in many worlds, or in any other theory.

Well OK but.... if you want all the details this is going to be a long post, you asked for it.

Yes, I asked for a detailed account of how MWI produces the correlations for  the entangled singlet state. The trouble is that you have not provided this. Your post is long and rambling, full of a lot of unnecessary detail, but the bottom line is the claim that since MWI is not realistic, it can be local. You have made that claim many times before, but the current post comes no nearer to giving a local explanation than any of your previous posts.

What is required is a local account, invoking many worlds as necessary, that can explain how the correlations are built up. In the usual Alice/Bob setup, when Alice measures her particle, she splits into two branches: in one of which she sees spin_up and in the other, spin_down. Similarly, Bob splits on his measurement into Bob_up and Bob_down branches. When Alice and Bob come together, each splits again according to which branch of the other they meet. So there are then four branches, up-up, up-down, down-up, and down-down for the results of Alice and Bob respectively. For all polarizer orientations apart from parallel or orthogonal, these four branches must exist. But for parallel or orthogonal polarizers only two branches are possible for an initial singlet state -- Alice and Bob must get opposite results, for parallel polarizers, and the same result for orthogonal polarizers. In other words the up-up and down-down branches do not exist for parallel polarizers. How is this magic achieved in many worlds?

Things are more complicated in the general case of polarizers at an arbitrary relative angle, theta. The question then is how do we manage the correlations between consecutive trials in order to preserve the cos^2(theta/2) probability. (Over a sequence of N trials, the proportion of up-down branches for polarizers at the relative angle theta must be approximately cos^2(theta/2)).

In a sequence of N trials, both Alice and Bob split into 2^N copies, each copy has a unique sequence of up and down results. When Alice and Bob meet, the usual MWI procedure means that there are (2^N)^(2^N) branches, as each of the 2^N branches for Alice meets the 2^N branches for Bob. Out of all these branches, only one has the matching sequence of up and down from each end required to get the correlations correct, How does MWI get rid of all the (2^N)^(2^N)-1 incorrect branches?

This is the question you are required to answer in detail,  without generalized fudging or appeals to magic.

Bruce

The issue is the extent to which there is subjectivity. With MWI we have this idea an observer is in a sense "quantum frame dragged" along eigenstates corresponding to all possible measurements, but is able to make a conscious account of only one. This observer witnesses this post-measurement state as a separable state that is local. However, if the observer is frame dragged along all possible paths there is a statistical ensemble of separable states, but we know this is not a separable state in total. What is an account of a separable state is then subjective to the observer.

This is to be compared to qubism, where the probability outcome is a subjective Bayesian update. There are some things to be said for Qubism IMO, though it has some almost solipsistic implications. Qubism is a ψ-epistemic interpretation while MWI is ψ-ontological, in that with qubism  assigns no particular existence to the wave function. The quantum wave of course has no operator assigned to it that gives an eigenvalue, but there is the density operator ρ = |ψ〉〈ψ| that defines probabilities. Probability is in qubism based again on Bayesian statistics considers these subjective. With MWI the wave function is treated more as a real, real in the existential sense than mathematical, object, but it is highly nonlocal. This splitting off of worlds is not tied to any point in space or spacetime, and if the wave is determined by field operators acting on a Fock basis, then field locality is not global. The subjectivity of the wave as separable means we have a conflict with the QFT axioms. This subjectivity is not with the probabilities, so much as it is with the interpretation of post-measurement states relative to re-measurement states. 

I am not particularly an upholder of any interpretation of quantum mechanics. At best either one uses the one which makes the best sense of some problem, or you just "shut up and calculate." Since quantum mechanics has this funny issue with the reduction of quantum states, the discontinuous transition of a pure quantum state to statistical mixtures or a single separable state, it all involves the issue to what extent the decoherence of quantum states by coupling a larger quantum system (measurement apparatus or observer) is at all computable. This is ultimately a process of encoding quantum numbers within a system of quantum numbers. Can this emulate the system observed, think of this as a Turing machine encoding other Turing machines, or a process of Gödel numbering that then act as the subject of a predicate. The shut-up-and-calculate approach might be compared to the Euclid 5th axiom that is not decidable, consistent but not complete, but where the negation of this axiom leads to a bouquet of alternate models that are complete but not consistent with each other. 

LC

[Lawrence Crowell]

On Sunday, March 6, 2022 at 5:57:28 AM UTC-6 Lawrence Crowell wrote:

On Friday, March 4, 2022 at 4:34:12 PM UTC-6 Bruce wrote:

On Sat, Mar 5, 2022 at 2:50 AM John Clark <johnk...@gmail.com> wrote:

On Thu, Mar 3, 2022 at 7:03 PM Bruce Kellett <bhkel...@gmail.com> wrote:

>> Just exchange the 2 slits in the experiments that I described with a polarizer and then the world would split because of polarization differences not because of which slip the photon went through, or if you prefer exchange the photons with electrons and the 2 slits with a Stern-Gerlach magnet, and then the world will split because of differences in spin of the electron; after that everything I said was still hold true, and nowhere would there be a need to invoke non-local influences. And you can build any Bell-type experiment you like with polarization or with spin,

> Yes. But you have to show how non-separable states can exhibit locality. Or, at least, you are required to show in detail how the correlation arise locally, in many worlds, or in any other theory.

Well OK but.... if you want all the details this is going to be a long post, you asked for it.

Yes, I asked for a detailed account of how MWI produces the correlations for  the entangled singlet state. The trouble is that you have not provided this. Your post is long and rambling, full of a lot of unnecessary detail, but the bottom line is the claim that since MWI is not realistic, it can be local. You have made that claim many times before, but the current post comes no nearer to giving a local explanation than any of your previous posts.

What is required is a local account, invoking many worlds as necessary, that can explain how the correlations are built up. In the usual Alice/Bob setup, when Alice measures her particle, she splits into two branches: in one of which she sees spin_up and in the other, spin_down. Similarly, Bob splits on his measurement into Bob_up and Bob_down branches. When Alice and Bob come together, each splits again according to which branch of the other they meet. So there are then four branches, up-up, up-down, down-up, and down-down for the results of Alice and Bob respectively. For all polarizer orientations apart from parallel or orthogonal, these four branches must exist. But for parallel or orthogonal polarizers only two branches are possible for an initial singlet state -- Alice and Bob must get opposite results, for parallel polarizers, and the same result for orthogonal polarizers. In other words the up-up and down-down branches do not exist for parallel polarizers. How is this magic achieved in many worlds?

Things are more complicated in the general case of polarizers at an arbitrary relative angle, theta. The question then is how do we manage the correlations between consecutive trials in order to preserve the cos^2(theta/2) probability. (Over a sequence of N trials, the proportion of up-down branches for polarizers at the relative angle theta must be approximately cos^2(theta/2)).

In a sequence of N trials, both Alice and Bob split into 2^N copies, each copy has a unique sequence of up and down results. When Alice and Bob meet, the usual MWI procedure means that there are (2^N)^(2^N) branches, as each of the 2^N branches for Alice meets the 2^N branches for Bob. Out of all these branches, only one has the matching sequence of up and down from each end required to get the correlations correct, How does MWI get rid of all the (2^N)^(2^N)-1 incorrect branches?

This is the question you are required to answer in detail,  without generalized fudging or appeals to magic.

Bruce

The issue is the extent to which there is subjectivity. With MWI we have this idea an observer is in a sense "quantum frame dragged" along eigenstates corresponding to all possible measurements, but is able to make a conscious account of only one. This observer witnesses this post-measurement state as a separable state that is local. However, if the observer is frame dragged along all possible paths there is a statistical ensemble of separable states, but we know this is not a separable state in total. What is an account of a separable state is then subjective to the observer.

This is to be compared to qubism, where the probability outcome is a subjective Bayesian update. There are some things to be said for Qubism IMO, though it has some almost solipsistic implications. Qubism is a ψ-epistemic interpretation while MWI is ψ-ontological, in that with qubism  assigns no particular existence to the wave function. The quantum wave of course has no operator assigned to it that gives an eigenvalue, but there is the density operator ρ = |ψ〉〈ψ| that defines probabilities. Probability is in qubism based again on Bayesian statistics considers these subjective. With MWI the wave function is treated more as a real, real in the existential sense than mathematical, object, but it is highly nonlocal. This splitting off of worlds is not tied to any point in space or spacetime, and if the wave is determined by field operators acting on a Fock basis, then field locality is not global. The subjectivity of the wave as separable means we have a conflict with the QFT axioms. This subjectivity is not with the probabilities, so much as it is with the interpretation of post-measurement states relative to re-measurement states. 

I meant pre-measurement. It is still early in the morning and my morning coffee has not fully kicked in. Sorry if the language is a bit garbled.

LC

[John Clark]

On Sun, Mar 6, 2022 at 6:57 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

> The issue is the extent to which there is subjectivity.

Yes, I agree. 

> With MWI we have this idea an observer is in a sense "quantum frame dragged" along eigenstates corresponding to all possible measurements, but is able to make a conscious account of only one.

I would say an "observer" very quickly becomes the "observers", and every one of them is able to make a conscious account of the state they are in,   

> This observer witnesses this [pre]-measurement state as a separable state that is local.

And another observer witnesses a post measurement state as a separate state that is local.  

> However,  if the observer is frame dragged along all possible paths

One observer is not dragged along every possible path, instead one observer is duplicated enough times to fill all possible paths. 

> there is a statistical ensemble of separable states, but we know this is not a separable state in total. What is an account of a separable state is then subjective to the observer.

Yes, some states are so nearly identical that they make no subjective difference to the observer; for example whether a butterfly in Brazil flaps its wings 3 times or 4 makes no subjective difference to an observer in New York (or at least not for a while, in a few months due to chaos it might make the difference between a blizzard hitting New York and missing it, but that's another matter). If 2 brains are identical then they're producing 2 identical conscious experiences, and in that case I don't think it would be meaningful to say there are 2 observers. Some wonder if there are an infinite number of worlds  how can Many Worlds get probabilities out of it, I think this is how, there may be an infinite number of worlds but there are only a finite number of beings who could reasonably call themselves "John Clark" or "Lawrence Crowell".

> This is to be compared to qubism, where the probability outcome is a subjective Bayesian update.

When calculating probability subjectivity cannot be ignored in the Many Worlds idea either.  

> There are some things to be said for Qubism IMO, though it has some almost solipsistic implications.

Yes, and that's one of the things I dislike about Qubism. I take it as an axiom of existence that I am not the only conscious being in the universe, I can't prove it's true but I can prove that I need to believe it in order to function.  

 

> Qubism is a ψ-epistemic interpretation while MWI is ψ-ontological,

Yes.

 

> in that with qubism  assigns no particular existence to the wave function.

That's another thing I dislike about Qubism, to me it seems uncomfortably close to the "shut up and calculate" school of thought.  Many Worlds is the most straightforward explanation of what's going on, it's what you get if you just keep following Schrodinger's Equation and don't just arbitrarily shut it down for no apparent reason with a wave collapse.

 

> The quantum wave of course has no operator assigned to it that gives an eigenvalue, but there is the density operator ρ = |ψ〉〈ψ| that defines probabilities. Probability is in qubism based again on Bayesian statistics considers these subjective. With MWI the wave function is treated more as a real, real in the existential sense than mathematical, object, but it is highly nonlocal. This splitting off of worlds is not tied to any point in space or spacetime

If the only difference between universes is the number of times a butterfly flaps its wings and the question is how fast the universe splits because of that difference it could be thought of in 2 ways, which you choose as a matter of taste. You could say the split starts at the butterfly and spreads outward at the speed of light, or you could say the entire universe splits instantaneously, both ideas produce identical results with no way to differentiate between the two.  

> At best either one uses the one which makes the best sense of some problem, or you just "shut up and calculate."

It seems to me if Einstein had just stuck with calculating Newtonian problems and hadn't even tried to think about how action at a distance could occur or about anything else that was actually going on he never would've found General Relativity. And "shut up and calculate" would turn science into an incredibly dull field of study.... when you changed the experimental set up of an experiment from state X to state Y the only thing you could conclude from that is that the reading on a voltmeter will decrease from 8 to 7, speculation on what was actually going on that could've caused that change would be forbidden.

> it all involves the issue to what extent the decoherence of quantum states by coupling a larger quantum system (measurement apparatus or observer) is at all computable.

Some problems in pure mathematics are not computable, but there's no evidence that any of them have anything to do with physics, and in fact there is no evidence that nature even knows how to solve NP-hard problems in polynomial time. Quantum Computer expert Scott Aaronson actually tested this, and this is what he found:

" Taking two glass plates with pegs between them, and dipping the resulting contraption into a tub of soapy water. The idea is that the soap bubbles that form between the pegs should trace out the minimum Steiner tree — that is, the minimum total length of line segments connecting the pegs, where the segments can meet at points other than the pegs themselves. Now, this is known to be an NP-hard optimization problem. So, it looks like Nature is solving NP-hard problems in polynomial time!

Long story short, I went to the hardware store, bought some glass plates, liquid soap, etc., and found that, while Nature does often find a minimum Steiner tree with 4 or 5 pegs, it tends to get stuck at local optima with larger numbers of pegs. Indeed, often the soap bubbles settle down to a configuration which is not even a tree (i.e. contains “cycles of soap”), and thus provably can’t be optimal.

The situation is similar for protein folding. Again, people have said that Nature seems to be solving an NP-hard optimization problem in every cell of your body, by letting the proteins fold into their minimum-energy configurations. But there are two problems with this claim. The first problem is that proteins, just like soap bubbles, sometimes get stuck in suboptimal configurations — indeed, it’s believed that’s exactly what happens with Mad Cow Disease. The second problem is that, to the extent that proteins do usually fold into their optimal configurations, there’s an obvious reason why they would: natural selection! If there were a protein that could only be folded by proving the Riemann Hypothesis, the gene that coded for it would quickly get weeded out of the gene pool." 

> The shut-up-and-calculate approach might be compared to the Euclid 5th axiom that is not decidable,

Euclid's 5th axiom might be decidable, not through mathematics but through physics and astronomy, and the best evidence we have so far is that it's true, the universe seems to have no overall global curvature. A better example might be the Continuum Hypothesis because that involves infinite sets and it's not clear if real physical lines actually do contain an infinite number of points, it's not even clear if an infinite number of anything that's physical exists.

> I am not particularly an upholder of any interpretation of quantum mechanics.

I'm not either really, I'm just saying Many Worlds is the least bad explanation of Quantum Mechanics that I know of, maybe tomorrow somebody will find a better one. But whatever the truth turns out to be there is one thing I feel certain of, it will be weird.  

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

lqc

[Lawrence Crowell]

There is a lot here that you wrote. Some does not seem to fit that consistently, if you ask me. Einstein had none of these issues with the development of GR, for at that time the conflict between our classical understanding and quantum mechanics was not known. GR is also a classical theory. 

Different interpretations do have different levels of effectiveness. Some are better than others. MWI is fair to decent. but it is not IMO way out in the lead.

LC

[John Clark]

On Mon, Mar 7, 2022 at 6:49 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

> There is a lot here that you wrote. Some does not seem to fit that consistently, if you ask me. Einstein had none of these issues with the development of GR,

If he had Einstein never would've found General Relativity.  

> for at that time the conflict between our classical understanding and quantum mechanics was not known.

Quantum Mechanics was not the first time it was realized that although there was a theory that could predict what would occur in an experiment it wasn't clear just what was going on at a deeper level, but Newton said he refused to speculate on the mechanism behind action at a distance. Fortunately Einstein refused to take Newton's advice and speculated anyway.  

> GR is also a classical theory. 

I know, but it was a revolutionary theory, and Quantum Mechanics does not have a monopoly on mystery.  

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

mqt

lqcm