Sean Carroll's Google talk about his book

[John Clark]

As far as I know dispite lots of talk about it I'm STILL the only one on the list that has actually read Carroll's new book, but he gave an excellent Google talk about it on Friday so maybe his critics will at least watch that; after all even an abbreviated Cliff Notes knowledge of a book is better than no knowledge at all.

Sean Carroll's Google talk about his new book "Something Deeply Hidden"

John K Clark

[Philip Thrift]

Even this video, I don't think, will change Jim Baggott's view.

https://groups.google.com/d/msg/everything-list/74MhjpQg_g8/tuoTw1mEBQAJ

@philipthrift 

[John Clark]

On Mon, Oct 7, 2019 at 6:05 PM Philip Thrift <cloud...@gmail.com> wrote:

>> As far as I know despite lots of talk about it I'm STILL the only one on the list that has actually read Carroll's new book, but he gave an excellent Google talk about it on Friday so maybe his critics will at least watch that; after all even an abbreviated Cliff Notes knowledge of a book is better than no knowledge at all.

Sean Carroll's Google talk about his new book "Something Deeply Hidden"

John K Clark

> Even this video, I don't think, will change Jim Baggott's view.

And so people continue to hold strong opinions about Carroll's book despite not having read it or even watched the "Something Deeply Hidden For Dummies" version of it. 

 John K Clark

 

[Lawrence Crowell]

On Monday, October 7, 2019 at 4:21:27 PM UTC-5, John Clark wrote:

I have read Carroll and Sebens' paper on this, which is more rigorous and less qualitative. I honestly do not have a yay or nay opinion on this. It is something to store away in the mental toolbox. Quantum interpretations are to my thinking unprovable theoretically and not falsifiable empirically. 

LC

[Philip Thrift]

Here is the Schrödinger equation [Wikipedia] in a historical context:

The Schrödinger equation is not the only way to study quantum mechanical systems and make predictions. The other formulations of quantum mechanics include matrix mechanics, introduced by Werner Heisenberg, and the path integral formulation, developed chiefly by Richard Feynman. Paul Dirac incorporated matrix mechanics and the Schrödinger equation into a single formulation.

Main article: Interpretations of quantum mechanics

The Schrödinger equation provides a way to calculate the wave function of a system and how it changes dynamically in time. However, the Schrödinger equation does not directly say what, exactly, the wave function is. Interpretations of quantum mechanics address questions such as what the relation is between the wave function, the underlying reality, and the results of experimental measurements.

An important aspect is the relationship between the Schrödinger equation and wave function collapse. In the oldest Copenhagen interpretation, particles follow the Schrödinger equation except during wave function collapse, during which they behave entirely differently. The advent of quantum decoherence theory allowed alternative approaches (such as the Everett many-worlds interpretation and consistent histories), wherein the Schrödinger equation is always satisfied, and wave function collapse should be explained as a consequence of the Schrödinger equation.

In 1952, Erwin Schrödinger gave a lecture during which he commented,

Nearly every result [a quantum theorist] pronounces is about the probability of this or that or that ... happening—with usually a great many alternatives. The idea that they be not alternatives but all really happen simultaneously seems lunatic to him, just impossible.

David Deutsch regarded this as the earliest known reference to a many-worlds interpretation of quantum mechanics, an interpretation generally credited to Hugh Everett III,^[ while Jeffrey A. Barrett took the more modest position that it indicates a "similarity in ... general views" between Schrödinger and Everett.

Any Rashomon "interpretation" of this probability-calculating formula [the probability of this or that or that - as Schrödinger] in terms of an underlying should not be presented to the public on a book tour as settled truth. There are the alternatives noted above, and unless some new observations are made, there are a dozen (or even dozens) of views that one can adopt.

To a probability theorist though, Carroll appears something like a pseudoscientist. I just can't see how his attempt at a probability measure on "many worlds" works, vs. "a sample space Ω of possible histories."

Hilbert Spaces from Path Integrals - https://arxiv.org/abs/1002.0589

@philipthrift

 

[Bruce Kellett]

I watched a little of Sean's talk at Google. It is a very slick marketing exercise -- reminded me of a con man, or a snake oil salesman. Too slick by half.

Bruce 

[Philip Thrift]

It's like watching an indoctrinated religious missionary.

@philipthrift

[John Clark]

On Tue, Oct 8, 2019 at 3:10 AM Bruce Kellett <bhkel...@gmail.com> wrote:

> I watched a little of Sean's talk at Google. It is a very slick marketing exercise -- reminded me of a con man, or a snake oil salesman. Too slick by half.

So you haven't read a word of Carroll's book and you even stopped watching his talk about his book after a few minutes, and you did so not because you could find anything substantively wrong with the talk but because you just didn't like his style for some vague reason; but none of that prevents you from saying with great authority that the book is all wrong and writing ponderous screeds damning his book to hell. 

 John K Clark

[Bruce Kellett]

I think you are over-reacting somewhat, John. I haven't read Carroll's book because it is not available in Australia yet. I watched most of the lecture, and was put off by the style and the lack of substance.

I don't know what ponderous screeds from me that you have been reading that damn Carroll's book -- I haven't written anything about his book, although I have written at length about the troubles with MWI, and the failure of MWI to provide an adequate local causal account of the violation of the Bell inequalities. Now, maybe Carroll has a convincing explanation of this. If he has, and you have read it in his book, then please reproduce it here so that we can all share in this insight. 

Bruce

[John Clark]

on Tue, Oct 8, 2019 at 7:36 AM Bruce Kellett <bhkel...@gmail.com> wrote:

 > I watched most of the lecture, and was put off by the style and the lack of substance.

How much of Carroll's talk did you actually watch? If it was more than 90 seconds you'd know it did not lack substance. And I liked his style because it was crystal clear and he did not do what so many do, explain what he's going to say, then say it, them explain what he just said; instead Carroll cuts the crap and just says it.

John K Clark

[Brent Meeker]

What do you think he's selling?  I think Carroll is a good speaker, a good popularizer, and a nice guy.  I feel fortunate to have him representing physics to the public.  He is not evangelizing for some particular interpretation and he recognizes that there are alternative interpretations of QM even though he favors MWI.

Also, he's the only scientist who debated William Lane Craig and won by every measure.

Brent

[Philip Thrift]

Sean Carroll reminds me more of Alvin Plantinga 

   https://en.wikipedia.org/wiki/Alvin_Plantinga

who can take math and pull out God.

Carroll makes the big mistake of a number of physics "popularizers" today. He takes the mathematical language of a physical theory (or one version* of that theory, as there are multiple formulations of quantum theory) and pulls a physical ontology out of his math.

The math is not the territory.

* The Schrödinger equation is not the only way to study quantum mechanical systems and make predictions. The other formulations of quantum mechanics include matrix mechanics, introduced by Werner Heisenberg, and the path integral formulation, developed chiefly by Richard Feynman. Paul Dirac incorporated matrix mechanics and the Schrödinger equation into a single formulation.

The Schrödinger equation provides a way to calculate the wave function of a system and how it changes dynamically in time. However, the Schrödinger equation does not directly say what, exactly, the wave function is. Interpretations of quantum mechanics address questions such as what the relation is between the wave function, the underlying reality, and the results of experimental measurements.

@philipthrift

 

[Brent Meeker]

On 10/8/2019 11:21 AM, Philip Thrift wrote:

On Tuesday, October 8, 2019 at 12:35:25 PM UTC-5, Brent wrote:

On 10/8/2019 12:10 AM, Bruce Kellett wrote:

On Tue, Oct 8, 2019 at 10:13 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

On Monday, October 7, 2019 at 4:21:27 PM UTC-5, John Clark wrote:

As far as I know dispite lots of talk about it I'm STILL the only one on the list that has actually read Carroll's new book, but he gave an excellent Google talk about it on Friday so maybe his critics will at least watch that; after all even an abbreviated Cliff Notes knowledge of a book is better than no knowledge at all.

Sean Carroll's Google talk about his new book "Something Deeply Hidden"

John K Clark

I have read Carroll and Sebens' paper on this, which is more rigorous and less qualitative. I honestly do not have a yay or nay opinion on this. It is something to store away in the mental toolbox. Quantum interpretations are to my thinking unprovable theoretically and not falsifiable empirically. 

I watched a little of Sean's talk at Google. It is a very slick marketing exercise -- reminded me of a con man, or a snake oil salesman. Too slick by half.

What do you think he's selling?  I think Carroll is a good speaker, a good popularizer, and a nice guy.  I feel fortunate to have him representing physics to the public.  He is not evangelizing for some particular interpretation and he recognizes that there are alternative interpretations of QM even though he favors MWI.

Also, he's the only scientist who debated William Lane Craig and won by every measure.

Brent

Sean Carroll reminds me more of Alvin Plantinga 

   https://en.wikipedia.org/wiki/Alvin_Plantinga

who can take math and pull out God.

Carroll makes the big mistake of a number of physics "popularizers" today. He takes the mathematical language of a physical theory (or one version* of that theory, as there are multiple formulations of quantum theory) and pulls a physical ontology out of his math.

That's why it's called an "interpretation".  Every physical theory has an ontology that goes with it's mathematics, otherwise you don't know how to apply the mathematics.  That MWI entails other, unobservable "worlds" is neither a bug or a feature, it's just one answer to the measurement problem.  If you have a better answer, feel free to state it.

The math is not the territory.

* The Schrödinger equation is not the only way to study quantum mechanical systems and make predictions. The other formulations of quantum mechanics include matrix mechanics, introduced by Werner Heisenberg, and the path integral formulation, developed chiefly by Richard Feynman. Paul Dirac incorporated matrix mechanics and the Schrödinger equation into a single formulation.

The Schrödinger equation provides a way to calculate the wave function of a system and how it changes dynamically in time. However, the Schrödinger equation does not directly say what, exactly, the wave function is. Interpretations of quantum mechanics address questions such as what the relation is between the wave function, the underlying reality, and the results of experimental measurements.

Did you write that, or are you quoting without attribution?  Anyway it's common knowledge on this list.

Brent

[Alan Grayson]

On Tuesday, October 8, 2019 at 1:40:33 PM UTC-6, Brent wrote:

On 10/8/2019 11:21 AM, Philip Thrift wrote:

On Tuesday, October 8, 2019 at 12:35:25 PM UTC-5, Brent wrote:

On 10/8/2019 12:10 AM, Bruce Kellett wrote:

On Tue, Oct 8, 2019 at 10:13 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

On Monday, October 7, 2019 at 4:21:27 PM UTC-5, John Clark wrote:

As far as I know dispite lots of talk about it I'm STILL the only one on the list that has actually read Carroll's new book, but he gave an excellent Google talk about it on Friday so maybe his critics will at least watch that; after all even an abbreviated Cliff Notes knowledge of a book is better than no knowledge at all.

Sean Carroll's Google talk about his new book "Something Deeply Hidden"

John K Clark

I have read Carroll and Sebens' paper on this, which is more rigorous and less qualitative. I honestly do not have a yay or nay opinion on this. It is something to store away in the mental toolbox. Quantum interpretations are to my thinking unprovable theoretically and not falsifiable empirically. 

I watched a little of Sean's talk at Google. It is a very slick marketing exercise -- reminded me of a con man, or a snake oil salesman. Too slick by half.

What do you think he's selling?  I think Carroll is a good speaker, a good popularizer, and a nice guy.  I feel fortunate to have him representing physics to the public.  He is not evangelizing for some particular interpretation and he recognizes that there are alternative interpretations of QM even though he favors MWI.

Also, he's the only scientist who debated William Lane Craig and won by every measure.

Brent

Sean Carroll reminds me more of Alvin Plantinga 

   https://en.wikipedia.org/wiki/Alvin_Plantinga

who can take math and pull out God.

Carroll makes the big mistake of a number of physics "popularizers" today. He takes the mathematical language of a physical theory (or one version* of that theory, as there are multiple formulations of quantum theory) and pulls a physical ontology out of his math.

That's why it's called an "interpretation".  Every physical theory has an ontology that goes with it's mathematics, otherwise you don't know how to apply the mathematics. 

What is "an ontology"? Seems to me this is a red herring; no way to find evidence that something is real, as opposed to illusionary, unless you apply Vic's claim; it's "real" if it kicks back! Does S's equation kick back? Depends on who you talk to, unlike EM waves. Real or not, S's equation can be used for calculatons. Doesn't matter what its ontological status is. AG 

[Philip Thrift]

That's from Wikipedia again (same quote from the Schrödinger equation article posted several times before). That " it's common knowledge on this list" doesn't appear that way at all, where an undisputed catechism is assumed on what is real (QM-wise).

I just don't see how Many Worlds ontology tells us "how to apply the mathematics": We don't observe a bunch of worlds, so how can it be applied?

Path-integral methods are already used extensively in computational quantum mechanics CQM) and applied in materials science and other application areas. So we know they are useful. 

Where are the many-world methods used in CQM.

@philpthift   

[Philip Thrift]

On Tuesday, October 8, 2019 at 2:58:04 PM UTC-5, Alan Grayson wrote:

On Tuesday, October 8, 2019 at 1:40:33 PM UTC-6, Brent wrote:

On 10/8/2019 11:21 AM, Philip Thrift wrote:

On Tuesday, October 8, 2019 at 12:35:25 PM UTC-5, Brent wrote:

On 10/8/2019 12:10 AM, Bruce Kellett wrote:

On Tue, Oct 8, 2019 at 10:13 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

On Monday, October 7, 2019 at 4:21:27 PM UTC-5, John Clark wrote:

As far as I know dispite lots of talk about it I'm STILL the only one on the list that has actually read Carroll's new book, but he gave an excellent Google talk about it on Friday so maybe his critics will at least watch that; after all even an abbreviated Cliff Notes knowledge of a book is better than no knowledge at all.

Sean Carroll's Google talk about his new book "Something Deeply Hidden"

John K Clark

I have read Carroll and Sebens' paper on this, which is more rigorous and less qualitative. I honestly do not have a yay or nay opinion on this. It is something to store away in the mental toolbox. Quantum interpretations are to my thinking unprovable theoretically and not falsifiable empirically. 

I watched a little of Sean's talk at Google. It is a very slick marketing exercise -- reminded me of a con man, or a snake oil salesman. Too slick by half.

What do you think he's selling?  I think Carroll is a good speaker, a good popularizer, and a nice guy.  I feel fortunate to have him representing physics to the public.  He is not evangelizing for some particular interpretation and he recognizes that there are alternative interpretations of QM even though he favors MWI.

Also, he's the only scientist who debated William Lane Craig and won by every measure.

Brent

Sean Carroll reminds me more of Alvin Plantinga 

   https://en.wikipedia.org/wiki/Alvin_Plantinga

who can take math and pull out God.

Carroll makes the big mistake of a number of physics "popularizers" today. He takes the mathematical language of a physical theory (or one version* of that theory, as there are multiple formulations of quantum theory) and pulls a physical ontology out of his math.

That's why it's called an "interpretation".  Every physical theory has an ontology that goes with it's mathematics, otherwise you don't know how to apply the mathematics. 

What is "an ontology"? Seems to me this is a red herring; no way to find evidence that something is real, as opposed to illusionary, unless you apply Vic's claim; it's "real" if it kicks back! Does S's equation kick back? Depends on who you talk to, unlike EM waves. Real or not, S's equation can be used for calculatons. Doesn't matter what its ontological status is. AG 

That's it right there.

the Schrödinger equation does not directly say what, exactly, the wave function is  [Wikipedia: Schrödinger_equation]

 

I haven't seen yet where MWI serves any useful purpose.

At least path integrals are used in applications. (But not many worlds.)

@phiipthrift

[Bruce Kellett]

On Wed, Oct 9, 2019 at 4:35 AM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

On 10/8/2019 12:10 AM, Bruce Kellett wrote:

I watched a little of Sean's talk at Google. It is a very slick marketing exercise -- reminded me of a con man, or a snake oil salesman. Too slick by half.

What do you think he's selling?

His book? Actually, he is selling a particular approach to QM, and claiming, in no uncertain terms, that his is the only "true" approach. I take particular exception to his claim that MWI is the SWE and nothing else. He elides the many additional assumptions that he has to make to get correspondence with experience, but derides other approaches for making assumptions! That is just dishonest.

I think Carroll is a good speaker, a good popularizer, and a nice guy.

He is certainly a polished speaker, and is probably a nice guy. But that does not make him right.

 

  I feel fortunate to have him representing physics to the public.  He is not evangelizing for some particular interpretation and he recognizes that there are alternative interpretations of QM even though he favors MWI.

Maybe so in his book, but that was not apparent in the lecture.

 

Also, he's the only scientist who debated William Lane Craig and won by every measure.

Bully for him. Debating William Lane Craig is not the height of science......

Bruce

[Philip Thrift]

On Tuesday, October 8, 2019 at 2:40:33 PM UTC-5, Brent wrote:

That MWI entails other, unobservable "worlds" is neither a bug or a feature, it's just one answer to the measurement problem.  If you have a better answer, feel free to state it.

Brent

MWI, according to Sabine Hossenfelder, is not an answer - in the final analysis - to the measurement problem

http://backreaction.blogspot.com/2019/09/the-trouble-with-many-worlds.html

The many world interpretation, now, supposedly does away with the problem of the quantum measurement and it does this by just saying there isn’t such a thing as wavefunction collapse. Instead, many worlds people say, every time you make a measurement, the universe splits into several parallel worlds, one for each possible measurement outcome. This universe splitting is also sometimes called branching.

Some people have a problem with the branching because it’s not clear just exactly when or where it should take place, but I do not think this is a serious problem, it’s just a matter of definition. No, the real problem is that after throwing out the measurement postulate, the many worlds interpretation needs another assumption, that brings the measurement problem back.

The reason is this. In the many worlds interpretation, if you set up a detector for a measurement, then the detector will also split into several universes. Therefore, if you just ask “what will the detector measure”, then the answer is “The detector will measure anything that’s possible with probability 1.”

This, of course, is not what we observe. We observe only one measurement outcome. The many worlds people explain this as follows. Of course you are not supposed to calculate the probability for each branch of the detector. Because when we say detector, we don’t mean all detector branches together. You should only evaluate the probability relative to the detector in one specific branch at a time.

That sounds reasonable. Indeed, it is reasonable. It is just as reasonable as the measurement postulate. In fact, it is logically entirely equivalent to the measurement postulate. The measurement postulate says: Update probability at measurement to 100%. The detector definition in many worlds says: The “Detector” is by definition only the thing in one branch. Now evaluate probabilities relative to this, which gives you 100% in each branch. Same thing.

And because it’s the same thing you already know that you cannot derive this detector definition from the Schrödinger equation. It’s not possible. What the many worlds people are now trying instead is to derive this postulate from rational choice theory. But of course that brings back in macroscopic terms, like actors who make decisions and so on. In other words, this reference to knowledge is equally in conflict with reductionism as is the Copenhagen interpretation.

And that’s why the many worlds interpretation does not solve the measurement problem and therefore it is equally troubled as all other interpretations of quantum mechanics. What’s the trouble with the other interpretations? We will talk about this some other time. So stay tuned.

@philipthrift

[Brent Meeker]

On 10/8/2019 12:58 PM, Alan Grayson wrote:

On Tuesday, October 8, 2019 at 1:40:33 PM UTC-6, Brent wrote:

On 10/8/2019 11:21 AM, Philip Thrift wrote:

On Tuesday, October 8, 2019 at 12:35:25 PM UTC-5, Brent wrote:

On 10/8/2019 12:10 AM, Bruce Kellett wrote:

On Tue, Oct 8, 2019 at 10:13 AM Lawrence Crowell <goldenfield...@gmail.com> wrote:

On Monday, October 7, 2019 at 4:21:27 PM UTC-5, John Clark wrote:

As far as I know dispite lots of talk about it I'm STILL the only one on the list that has actually read Carroll's new book, but he gave an excellent Google talk about it on Friday so maybe his critics will at least watch that; after all even an abbreviated Cliff Notes knowledge of a book is better than no knowledge at all.

Sean Carroll's Google talk about his new book "Something Deeply Hidden"

John K Clark

I have read Carroll and Sebens' paper on this, which is more rigorous and less qualitative. I honestly do not have a yay or nay opinion on this. It is something to store away in the mental toolbox. Quantum interpretations are to my thinking unprovable theoretically and not falsifiable empirically. 

I watched a little of Sean's talk at Google. It is a very slick marketing exercise -- reminded me of a con man, or a snake oil salesman. Too slick by half.

What do you think he's selling?  I think Carroll is a good speaker, a good popularizer, and a nice guy.  I feel fortunate to have him representing physics to the public.  He is not evangelizing for some particular interpretation and he recognizes that there are alternative interpretations of QM even though he favors MWI.

Also, he's the only scientist who debated William Lane Craig and won by every measure.

Brent

Sean Carroll reminds me more of Alvin Plantinga 

   https://en.wikipedia.org/wiki/Alvin_Plantinga

who can take math and pull out God.

Carroll makes the big mistake of a number of physics "popularizers" today. He takes the mathematical language of a physical theory (or one version* of that theory, as there are multiple formulations of quantum theory) and pulls a physical ontology out of his math.

That's why it's called an "interpretation".  Every physical theory has an ontology that goes with it's mathematics, otherwise you don't know how to apply the mathematics. 

What is "an ontology"? Seems to me this is a red herring; no way to find evidence that something is real, as opposed to illusionary, unless you apply Vic's claim; it's "real" if it kicks back! Does S's equation kick back? Depends on who you talk to, unlike EM waves. Real or not, S's equation can be used for calculatons. Doesn't matter what its ontological status is. AG

It matters in applying the theory.  In CI you apply the theory by evolving a wf forward in time from an initial state.  So the ontology includes a "state" which is some initial wf.  But you could do a consistent histories calculation in which the ontology includes and initial and a final state.  Or a transactional interpretation in which there  is an initial and final measurement result.

Brent

That MWI entails other, unobservable "worlds" is neither a bug or a feature, it's just one answer to the measurement problem.  If you have a better answer, feel free to state it.

The math is not the territory.

* The Schrödinger equation is not the only way to study quantum mechanical systems and make predictions. The other formulations of quantum mechanics include matrix mechanics, introduced by Werner Heisenberg, and the path integral formulation, developed chiefly by Richard Feynman. Paul Dirac incorporated matrix mechanics and the Schrödinger equation into a single formulation.

The Schrödinger equation provides a way to calculate the wave function of a system and how it changes dynamically in time. However, the Schrödinger equation does not directly say what, exactly, the wave function is. Interpretations of quantum mechanics address questions such as what the relation is between the wave function, the underlying reality, and the results of experimental measurements.

Did you write that, or are you quoting without attribution?  Anyway it's common knowledge on this list.

Brent

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[Philip Thrift]

On Tuesday, October 8, 2019 at 5:01:14 PM UTC-5, Brent wrote:

It [ontology] matters in applying the theory.  In CI you apply the theory by evolving a wf forward in time from an initial state.  So the ontology includes a "state" which is some initial wf.  But you could do a consistent histories calculation in which the ontology includes and initial and a final state.  Or a transactional interpretation in which there  is an initial and final measurement result.

Brent

I see where "histories ontology" is used in computational QM, but where is "worlds ontology" used (in QM software projects)?

@philipthrift

[Brent Meeker]

It tells us what we see and record is what in recorded by entanglement with the environment and ourselves and so solves the Schrodinger cat conundrum.  Whether you then adopt an axiom that says the the other branches predicted by the Schrodinger equation exist or vanish or "we just don't talk about them anymore" is a matter of choice.

Path-integral methods are already used extensively in computational quantum mechanics CQM) and applied in materials science and other application areas. So we know they are useful.

Don't all path-integral methods assume measurement in some form as a primitive?

Brent

[Brent Meeker]

On 10/8/2019 2:41 PM, Bruce Kellett wrote:

On Wed, Oct 9, 2019 at 4:35 AM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

On 10/8/2019 12:10 AM, Bruce Kellett wrote:

I watched a little of Sean's talk at Google. It is a very slick marketing exercise -- reminded me of a con man, or a snake oil salesman. Too slick by half.

What do you think he's selling?

His book? Actually, he is selling a particular approach to QM, and claiming, in no uncertain terms, that his is the only "true" approach.

No.  He explicitly says (at 14:45) he's going to explain the interpretation he favors but there are others which he discusses in his book.

I take particular exception to his claim that MWI is the SWE and nothing else. He elides the many additional assumptions that he has to make to get correspondence with experience, but derides other approaches for making assumptions! That is just dishonest.

What additional assumptions do you mean?

I think Carroll is a good speaker, a good popularizer, and a nice guy.

He is certainly a polished speaker, and is probably a nice guy. But that does not make him right.

 

  I feel fortunate to have him representing physics to the public.  He is not evangelizing for some particular interpretation and he recognizes that there are alternative interpretations of QM even though he favors MWI.

Maybe so in his book, but that was not apparent in the lecture.

 

Also, he's the only scientist who debated William Lane Craig and won by every measure.

Bully for him. Debating William Lane Craig is not the height of science......

No but several scientists have not done well at it, including Vic.

Brent

[Bruce Kellett]

On Wed, Oct 9, 2019 at 9:53 AM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

On 10/8/2019 2:41 PM, Bruce Kellett wrote:

On Wed, Oct 9, 2019 at 4:35 AM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

On 10/8/2019 12:10 AM, Bruce Kellett wrote:

I watched a little of Sean's talk at Google. It is a very slick marketing exercise -- reminded me of a con man, or a snake oil salesman. Too slick by half.

What do you think he's selling?

His book? Actually, he is selling a particular approach to QM, and claiming, in no uncertain terms, that his is the only "true" approach.

No.  He explicitly says (at 14:45) he's going to explain the interpretation he favors but there are others which he discusses in his book.

I was talking about my impression of the lecture, not of his book (which I haven't read). 

I take particular exception to his claim that MWI is the SWE and nothing else. He elides the many additional assumptions that he has to make to get correspondence with experience, but derides other approaches for making assumptions! That is just dishonest.

What additional assumptions do you mean?

What assumptions does he have to make to get a probability interpretation? Probability is not an evident property of the SE. Like many approaches to probability in Everett, he has to assume decoherence to distinguishable branches to get anywhere. But that relies on using the Born rule to justify ignoring branches with low amplitude -- the notorious "trace over environmental degrees of freedom". Sean's "self-locating uncertainty" is not well-defined. In the lecture he hints that the observer is uncertain about the fate of the cat until he opens the box -- until then he is uncertain of which branch he is on. But given the timescale of decoherence, he has branched within 10^{-20} sec, so the is no longer any "self-locating uncertainty" -- he is definitely on one branch or the other, he just doesn't know which. And that is just classical probability due to lack of knowledge -- nothing quantum about it. In another interview, he does suggest that the "self-locating uncertainty" lasts only until decoherence reaches the observer, at which time copies become entangled within each branch. Now if you can think relevant thoughts in 10^{-20} sec, then his argument might make some sense. But it fails to convince.....

I think Carroll is a good speaker, a good popularizer, and a nice guy.

He is certainly a polished speaker, and is probably a nice guy. But that does not make him right.

 

  I feel fortunate to have him representing physics to the public.  He is not evangelizing for some particular interpretation and he recognizes that there are alternative interpretations of QM even though he favors MWI.

Maybe so in his book, but that was not apparent in the lecture.

 

Also, he's the only scientist who debated William Lane Craig and won by every measure.

Bully for him. Debating William Lane Craig is not the height of science......

No but several scientists have not done well at it, including Vic.

That is probably an interest of yours. I fail to share it, and it is not science. There will always be people who fail to be convinced by science or by argument, and debating skills are not a prerequisite for good science.

Bruce 

[Brent Meeker]

On 10/8/2019 2:59 PM, Philip Thrift wrote:

On Tuesday, October 8, 2019 at 2:40:33 PM UTC-5, Brent wrote:

That MWI entails other, unobservable "worlds" is neither a bug or a feature, it's just one answer to the measurement problem.  If you have a better answer, feel free to state it.


Brent

MWI, according to Sabine Hossenfelder, is not an answer - in the final analysis - to the measurement problem

http://backreaction.blogspot.com/2019/09/the-trouble-with-many-worlds.html

The many world interpretation, now, supposedly does away with the problem of the quantum measurement and it does this by just saying there isn’t such a thing as wavefunction collapse. Instead, many worlds people say, every time you make a measurement, the universe splits into several parallel worlds, one for each possible measurement outcome. This universe splitting is also sometimes called branching.

Some people have a problem with the branching because it’s not clear just exactly when or where it should take place, but I do not think this is a serious problem, it’s just a matter of definition. No, the real problem is that after throwing out the measurement postulate, the many worlds interpretation needs another assumption, that brings the measurement problem back.

The reason is this. In the many worlds interpretation, if you set up a detector for a measurement, then the detector will also split into several universes. Therefore, if you just ask “what will the detector measure”, then the answer is “The detector will measure anything that’s possible with probability 1.”

This, of course, is not what we observe. We observe only one measurement outcome.

The implication is that the above two sentences are contrasting.  But nobody asks "what will the detector measure".  The question asked by the experimenter is "which measurement outcome will the detector detect", which is perfectly consistent with "we observe only one measurement outcome"

The many worlds people explain this as follows. Of course you are not supposed to calculate the probability for each branch of the detector. Because when we say detector, we don’t mean all detector branches together. You should only evaluate the probability relative to the detector in one specific branch at a time.

I can't even parse that.  You are supposed to calculate the probability of each possible measurement outcome and those characterize the branch.  It is NOT calculating "each branch of the detector" unless you are defining those "branches" by what the measurement outcome is.

That sounds reasonable. Indeed, it is reasonable. It is just as reasonable as the measurement postulate. In fact, it is logically entirely equivalent to the measurement postulate.

It's not clear here what "logically" equivalent means.  It is instrumentally equivalent...which is why it's an interpretation and not a different theory (as GRW is).  It's different from the measurement postulate in that the measurement postulate says the wave function instantaneously changes to match the observed measured value.  MWI says those other measured values obtain in other orthogonal subspaces of the Hilbert space and you are only observing one.  Those are not "logically" the same.

The measurement postulate says: Update probability at measurement to 100%. The detector definition in many worlds says: The “Detector” is by definition only the thing in one branch.

What does "only the thing in one branch mean". In MWI there are projections of the detector in subspaces which differ only by the value detected.

Now evaluate probabilities relative to this, which gives you 100% in each branch. Same thing.

And because it’s the same thing you already know that you cannot derive this detector definition from the Schrödinger equation.

?? You can't derive the definition of any physical object from the Schroedinger equation.  You put in the Hamiltonian of the object and whatever it interacts with and the initial ray in Hilbert space and the Schroedinger equation tells you how it evolves

It’s not possible. What the many worlds people are now trying instead is to derive this postulate from rational choice theory. But of course that brings back in macroscopic terms, like actors who make decisions and so on. In other words, this reference to knowledge is equally in conflict with reductionism as is the Copenhagen interpretation.

I agree with that point.  But once you suppose a probabilistic interpretation of the Hilbert space, then Gleason's theorem implies the Born rule.  That still leaves a small gap in saying why it has probabilistic interpretation at all.  Whether "self-locating uncertainty" is an adequate answer seems to me to require more analysis of human thought; although showing the brain is a quasi-classical information processor goes a long way.

Brent

And that’s why the many worlds interpretation does not solve the measurement problem and therefore it is equally troubled as all other interpretations of quantum mechanics. What’s the trouble with the other interpretations? We will talk about this some other time. So stay tuned.

@philipthrift

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[Brent Meeker]

On 10/8/2019 4:21 PM, Bruce Kellett wrote:

On Wed, Oct 9, 2019 at 9:53 AM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

On 10/8/2019 2:41 PM, Bruce Kellett wrote:

On Wed, Oct 9, 2019 at 4:35 AM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

On 10/8/2019 12:10 AM, Bruce Kellett wrote:

I watched a little of Sean's talk at Google. It is a very slick marketing exercise -- reminded me of a con man, or a snake oil salesman. Too slick by half.

What do you think he's selling?

His book? Actually, he is selling a particular approach to QM, and claiming, in no uncertain terms, that his is the only "true" approach.

No.  He explicitly says (at 14:45) he's going to explain the interpretation he favors but there are others which he discusses in his book.

I was talking about my impression of the lecture, not of his book (which I haven't read).

That's what I'm talking about; that's why I gave the time stamp of where he says it in the lecture.

I take particular exception to his claim that MWI is the SWE and nothing else. He elides the many additional assumptions that he has to make to get correspondence with experience, but derides other approaches for making assumptions! That is just dishonest.

What additional assumptions do you mean?

What assumptions does he have to make to get a probability interpretation? Probability is not an evident property of the SE. Like many approaches to probability in Everett, he has to assume decoherence to distinguishable branches to get anywhere. But that relies on using the Born rule to justify ignoring branches with low amplitude

The low amplitude branches aren't ignored.  Do you mean cross-terms in the density matrix?

-- the notorious "trace over environmental degrees of freedom". Sean's "self-locating uncertainty" is not well-defined.

I tend to agree with you there.  But if you assume that the human brain is a classical information processor of limited capacity I think you could get there.

In the lecture he hints that the observer is uncertain about the fate of the cat until he opens the box -- until then he is uncertain of which branch he is on. But given the timescale of decoherence, he has branched within 10^{-20} sec, so the is no longer any "self-locating uncertainty" -- he is definitely on one branch or the other, he just doesn't know which. And that is just classical probability due to lack of knowledge -- nothing quantum about it. In another interview, he does suggest that the "self-locating uncertainty" lasts only until decoherence reaches the observer, at which time copies become entangled within each branch. Now if you can think relevant thoughts in 10^{-20} sec, then his argument might make some sense. But it fails to convince.....

So you're faulting him for not calling 1e-20sec zero? Seems nit-picky.  I see the problem as sloppy introduction of "the observer" harking back to CI.  If observers are quasi-classical (no funny stuff in microtubles) then it should be enough to talk about uncertainty in the location of the geiger counter or the environment, but I understand Sean is trying to explain why, according to Everett, people don't see the superposition.

I think Carroll is a good speaker, a good popularizer, and a nice guy.

He is certainly a polished speaker, and is probably a nice guy. But that does not make him right.

 

  I feel fortunate to have him representing physics to the public.  He is not evangelizing for some particular interpretation and he recognizes that there are alternative interpretations of QM even though he favors MWI.

Maybe so in his book, but that was not apparent in the lecture.

 

Also, he's the only scientist who debated William Lane Craig and won by every measure.

Bully for him. Debating William Lane Craig is not the height of science......

No but several scientists have not done well at it, including Vic.

That is probably an interest of yours.

It was a big part of the interests on this list when Vic was writing his books. 

I fail to share it, and it is not science.

As Vic said, "Science isn't everything, but it's about everything." 

There will always be people who fail to be convinced by science or by argument, and debating skills are not a prerequisite for good science.

No, but they can be important in communicating good science to people...and we could certainly use more of that.

Brent

[Bruce Kellett]

On Wed, Oct 9, 2019 at 10:49 AM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

On 10/8/2019 4:21 PM, Bruce Kellett wrote:

On Wed, Oct 9, 2019 at 9:53 AM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

What additional assumptions do you mean?

What assumptions does he have to make to get a probability interpretation? Probability is not an evident property of the SE. Like many approaches to probability in Everett, he has to assume decoherence to distinguishable branches to get anywhere. But that relies on using the Born rule to justify ignoring branches with low amplitude

The low amplitude branches aren't ignored.  Do you mean cross-terms in the density matrix?

Explain to me how these are functionally different from low amplitude branches.

 

-- the notorious "trace over environmental degrees of freedom". Sean's "self-locating uncertainty" is not well-defined.

I tend to agree with you there.  But if you assume that the human brain is a classical information processor of limited capacity I think you could get there.

Only at the price of re-introducing the human observer into your exposition of QM. I thought that was the cardinal sin of the CI, and here Sean is bringing it back into Everett!!!!

In the lecture he hints that the observer is uncertain about the fate of the cat until he opens the box -- until then he is uncertain of which branch he is on. But given the timescale of decoherence, he has branched within 10^{-20} sec, so the is no longer any "self-locating uncertainty" -- he is definitely on one branch or the other, he just doesn't know which. And that is just classical probability due to lack of knowledge -- nothing quantum about it. In another interview, he does suggest that the "self-locating uncertainty" lasts only until decoherence reaches the observer, at which time copies become entangled within each branch. Now if you can think relevant thoughts in 10^{-20} sec, then his argument might make some sense. But it fails to convince.....

So you're faulting him for not calling 1e-20sec zero?

No. I am not faulting him for not calling it zero. I am faulting him for calling something that is uncertain in any quantum sense for 10^{-20} sec significant for the interpretation of probabilities.

 

Seems nit-picky.  I see the problem as sloppy introduction of "the observer" harking back to CI.

Yes, that is a point I have made.

 

If observers are quasi-classical (no funny stuff in microtubles) then it should be enough to talk about uncertainty in the location of the geiger counter or the environment, but I understand Sean is trying to explain why, according to Everett, people don't see the superposition.

That is achieved by decoherence and the preferred pointer basis. No need to introduce observers and self-locating uncertainty.

Bruce

[Bruce Kellett]

On Wed, Oct 9, 2019 at 10:24 AM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

On 10/8/2019 2:59 PM, Philip Thrift wrote:

That sounds reasonable. Indeed, it is reasonable. It is just as reasonable as the measurement postulate. In fact, it is logically entirely equivalent to the measurement postulate.

It's not clear here what "logically" equivalent means.  It is instrumentally equivalent...which is why it's an interpretation and not a different theory (as GRW is).  It's different from the measurement postulate in that the measurement postulate says the wave function instantaneously changes to match the observed measured value.  MWI says those other measured values obtain in other orthogonal subspaces of the Hilbert space and you are only observing one.  Those are not "logically" the same.

What do you mean by "logically equivalent"? It seems to me that if two assumptions fulfil the same explanatory role -- they are functionally equivalent -- then it is sensible to call them "logically equivalent". They fulfil the same logical role in the argument.

Bruce 

[Brent Meeker]

On 10/8/2019 5:03 PM, Bruce Kellett wrote:

On Wed, Oct 9, 2019 at 10:49 AM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

On 10/8/2019 4:21 PM, Bruce Kellett wrote:

On Wed, Oct 9, 2019 at 9:53 AM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

What additional assumptions do you mean?

What assumptions does he have to make to get a probability interpretation? Probability is not an evident property of the SE. Like many approaches to probability in Everett, he has to assume decoherence to distinguishable branches to get anywhere. But that relies on using the Born rule to justify ignoring branches with low amplitude

The low amplitude branches aren't ignored.  Do you mean cross-terms in the density matrix?

Explain to me how these are functionally different from low amplitude branches.

The branches are projections of the universal Hilbert ray onto (approximately) orthogonal subspaces corresponding to the preferred basis.  Cross terms are what make them approximate.  The cross-terms supposedly go to zero when you compute the reduced density matrix, but the diagonal terms don't go to zero...they measure the probability of the branches, including branches with low probability.

 

-- the notorious "trace over environmental degrees of freedom". Sean's "self-locating uncertainty" is not well-defined.

I tend to agree with you there.  But if you assume that the human brain is a classical information processor of limited capacity I think you could get there.

Only at the price of re-introducing the human observer into your exposition of QM. I thought that was the cardinal sin of the CI, and here Sean is bringing it back into Everett!!!!

Well, if you're going to explain why we experience a classical world, you're going to have to say something about experience.  To say it's information processing in the brain sounds pretty good to me.

In the lecture he hints that the observer is uncertain about the fate of the cat until he opens the box -- until then he is uncertain of which branch he is on. But given the timescale of decoherence, he has branched within 10^{-20} sec, so the is no longer any "self-locating uncertainty" -- he is definitely on one branch or the other, he just doesn't know which. And that is just classical probability due to lack of knowledge -- nothing quantum about it. In another interview, he does suggest that the "self-locating uncertainty" lasts only until decoherence reaches the observer, at which time copies become entangled within each branch. Now if you can think relevant thoughts in 10^{-20} sec, then his argument might make some sense. But it fails to convince.....

So you're faulting him for not calling 1e-20sec zero?

No. I am not faulting him for not calling it zero. I am faulting him for calling something that is uncertain in any quantum sense for 10^{-20} sec significant for the interpretation of probabilities.

But it's relevant to showing MWI is consistent with the experimenter not knowing which "world" he is in. He might not look at the data for a long time.

Brent

 

Seems nit-picky.  I see the problem as sloppy introduction of "the observer" harking back to CI.

Yes, that is a point I have made.

 

If observers are quasi-classical (no funny stuff in microtubles) then it should be enough to talk about uncertainty in the location of the geiger counter or the environment, but I understand Sean is trying to explain why, according to Everett, people don't see the superposition.

That is achieved by decoherence and the preferred pointer basis. No need to introduce observers and self-locating uncertainty.

Bruce

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[Brent Meeker]

I mean X=>Y and Y=>X.  But MWI entails some things that CI doesn't and vice versa.  In the C60 buckyball experiment CI doesn't give a very satisfactory account, because it doesn't have a good definition of "measure".  MWI introduced the idea of decoherence to fulfill that role without actually requiring a human observer.

Brent

[Bruce Kellett]

On Wed, Oct 9, 2019 at 11:36 AM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

On 10/8/2019 5:03 PM, Bruce Kellett wrote:

On Wed, Oct 9, 2019 at 10:49 AM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

On 10/8/2019 4:21 PM, Bruce Kellett wrote:

On Wed, Oct 9, 2019 at 9:53 AM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

What additional assumptions do you mean?

What assumptions does he have to make to get a probability interpretation? Probability is not an evident property of the SE. Like many approaches to probability in Everett, he has to assume decoherence to distinguishable branches to get anywhere. But that relies on using the Born rule to justify ignoring branches with low amplitude

The low amplitude branches aren't ignored.  Do you mean cross-terms in the density matrix?

Explain to me how these are functionally different from low amplitude branches.

The branches are projections of the universal Hilbert ray onto (approximately) orthogonal subspaces corresponding to the preferred basis.  Cross terms are what make them approximate.  The cross-terms supposedly go to zero when you compute the reduced density matrix, but the diagonal terms don't go to zero...they measure the probability of the branches, including branches with low probability.

It seems to me that that is what I said.

 

-- the notorious "trace over environmental degrees of freedom". Sean's "self-locating uncertainty" is not well-defined.

I tend to agree with you there.  But if you assume that the human brain is a classical information processor of limited capacity I think you could get there.

Only at the price of re-introducing the human observer into your exposition of QM. I thought that was the cardinal sin of the CI, and here Sean is bringing it back into Everett!!!!

Well, if you're going to explain why we experience a classical world, you're going to have to say something about experience.  To say it's information processing in the brain sounds pretty good to me.

But that is what he needs in order to introduce probabilities -- and that is just as circular as the Deutsch-Wallace use of decision theory -- both need observers to have a notion of probability.

 

In the lecture he hints that the observer is uncertain about the fate of the cat until he opens the box -- until then he is uncertain of which branch he is on. But given the timescale of decoherence, he has branched within 10^{-20} sec, so the is no longer any "self-locating uncertainty" -- he is definitely on one branch or the other, he just doesn't know which. And that is just classical probability due to lack of knowledge -- nothing quantum about it. In another interview, he does suggest that the "self-locating uncertainty" lasts only until decoherence reaches the observer, at which time copies become entangled within each branch. Now if you can think relevant thoughts in 10^{-20} sec, then his argument might make some sense. But it fails to convince.....

So you're faulting him for not calling 1e-20sec zero?

No. I am not faulting him for not calling it zero. I am faulting him for calling something that is uncertain in any quantum sense for 10^{-20} sec significant for the interpretation of probabilities.

But it's relevant to showing MWI is consistent with the experimenter not knowing which "world" he is in. He might not look at the data for a long time.

Exactly. So his "uncertainty" is purely classical. That is not an explanation of quantum probabilities. Remember, the Everettian promise is that the concept of "an observer" is irrelevant for understanding the theory -- it is all in the SWE. The theory provides its own explanation......

Bruce 

[Bruce Kellett]

That explanation of "measurement" is every bit as available to the CI theorist as to the Everettian theorist. As Peter Woit pointed out a while back, there is not much different between Everett and Copenhagen. Both can work with "its quantum all the way down", and develop the same understanding of "measurement". There is nothing particularly "many worlds" in the notion of decoherence.

Bruce 

[Brent Meeker]

But at some point where MWI says we can ignore the other "worlds", CI says the wf collapses...implying collapse is a physical process. I actually like the QBist idea that collapse is just something we do to our world description.

Brent

[Bruce Kellett]

Maybe the difference is just a metaphysical quibble -- and I eschew metaphysical quibbles. :-)

 

Bruce

[Philip Thrift]

On Tuesday, October 8, 2019 at 6:21:29 PM UTC-5, Bruce wrote:

 classical probability due to lack of knowledge -- nothing quantum about it

 

Bruce 

Even before QM came on the scene, there were competing and differing ideas of probability, including "knowledge-independent" (3.):

 

https://plato.stanford.edu/entries/probability-interpret/

Broadly speaking, there are arguably three main concepts of probability:

1. An epistemological concept, which is meant to measure objective evidential support relations. For example, “in light of the relevant seismological and geological data, California will probably experience a major earthquake this decade”.
2. The concept of an agent’s degree of confidence, a graded belief. For example, “I am not sure that it will rain in Canberra this week, but it probably will.”
3. A physical concept that applies to various systems in the world, independently of what anyone thinks. For example, “a particular radium atom will probably decay within 10,000 years”.

3. is present in Epicurus to C. S. Peirce.

@philipthrift

[Philip Thrift]

Sabine later goes on in a comment to say that 

       "to correctly sum up the total energy, you have to weigh the energy in each branch

       with the probability of that branch"

In the end, I think Sabine's application of probability is a  mess.

And to put "self-locating uncertainty" into the mix (now QM is human-brain dependent) makes things worse.

I posted a course notes of a pedagogical approach of applying probability theory to the conventional Hilbert space QM here:

       

       Quantum Probability Theory (by Jan Swart)

       https://groups.google.com/d/msg/everything-list/8_RCIBNbOis/0Qnlt_GyBQAJ

So  QPT and QMT (Quantum Measure Theory, by Rafael Sorkin) both take probability seriously in a mathematically pedagogical way, but in Many Worlds (Interpretation) it just looks like a Mega Waste.

@philipthrift 

[John Clark]

On Tue, Oct 8, 2019 at 4:54 PM Philip Thrift <cloud...@gmail.com> wrote:

> I haven't seen yet where MWI serves any useful purpose.

If you're only interested in making a better widget then the MWI has no useful purpose and you should just stick with the Shut Up And Calculate Interpretation, but if you have any interest at all in understanding reality at a somewhat deeper level you may not find that interpretation to be entirely satisfactory.

 John K Clark

[John Clark]

On Tue, Oct 8, 2019 at 5:41 PM Bruce Kellett <bhkel...@gmail.com> wrote:

>> What do you think he's selling?

His book? Actually, he is selling a particular approach to QM, and claiming, in no uncertain terms, that his is the only "true" approach.

Such slander gives me rock solid proof that not only have you not read Carroll's book you haven't even bothered to watch his short one hour talk about his book. And yet you continue to spend hours writing posts about it. 

 John K Clark

[Philip Thrift]

 MWI is not the one and only  alternative to SUACI (Shut Up And Calculate Interpretation).

Other interpretations (but not MWI, as far as I can see) are used in writing programs for computational QM.

@philipthrift

[John Clark]

On Wed, Oct 9, 2019 at 4:55 PM Philip Thrift <cloud...@gmail.com> wrote:

> Other interpretations (but not MWI, as far as I can see) are used in writing programs for computational QM.

Like what?

John K Clark

[Philip Thrift]

Multiple Histories.

@philipthrift 

[Quentin Anciaux]

https://en.wikipedia.org/wiki/Multiple_histories  ?

So there are multiple "worlds", if multiple past histories are real.... so as you dislike MWI, what's different here for you to accept multiple past ? (because if each event has multiple *real* past then likewise it has multiple *real* future).

Quentin 

@philipthrift 

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[Philip Thrift]

On Thursday, October 10, 2019 at 2:40:53 AM UTC-5, Quentin Anciaux wrote:

Le jeu. 10 oct. 2019 à 09:34, Philip Thrift <cloud...@gmail.com> a écrit :

On Wednesday, October 9, 2019 at 3:59:50 PM UTC-5, John Clark wrote:

On Wed, Oct 9, 2019 at 4:55 PM Philip Thrift <cloud...@gmail.com> wrote:

> Other interpretations (but not MWI, as far as I can see) are used in writing programs for computational QM.

Like what?

John K Clark

Multiple Histories.

https://en.wikipedia.org/wiki/Multiple_histories  ?

So there are multiple "worlds", if multiple past histories are real.... so as you dislike MWI, what's different here for you to accept multiple past ? (because if each event has multiple *real* past then likewise it has multiple *real* future).

Quentin

--

All those moments will be lost in time, like tears in rain. (Roy Batty/Rutger Hauer)

That's one way to look at it.

In Fay Dowker's debate with a Many Worlder:

via https://www.imperial.ac.uk/people/f.dowker

In this public debate I argue that the path integral (or sum over histories) approach to quantum mechanics provides a One World interpretation

 

Bottom line: multiple histories are cheaper than many worlds.

@philipthrift

[John Clark]

On Thu, Oct 10, 2019 at 3:34 AM Philip Thrift <cloud...@gmail.com> wrote:

>>> Other interpretations (but not MWI, as far as I can see) are used in writing programs for computational QM.

>> Like what?

> Multiple Histories.

And Multiple Histories uses path integral formulation and path integral formulation uses renormalization theory which is entirely in sympathy with the Shut Up And Calculate Interpretation; it's a wonderful way of getting the right answer, Feynman won a Nobel Prize for inventing it, but he was never entirely comfortable with it because it gave no coherent mental picture. He didn't even try to hide the imperfections in his idea. In his Nobel lecture Feynman said:

 "I don’t think we have a completely satisfactory relativistic quantum-mechanical model, even one that doesn’t agree with nature, but, at least, agrees with the logic that the sum of probability of all alternatives has to be 100%. Therefore, I think that the renormalization theory is simply a way to sweep the difficulties of the divergences of electrodynamics under the rug. I am, of course, not sure of that."

He is also well known for saying:

"I think I can safely say that nobody understands quantum mechanics."

John K Clark

[Bruce Kellett]

On Thu, Oct 10, 2019 at 9:29 PM John Clark <johnk...@gmail.com> wrote:

On Thu, Oct 10, 2019 at 3:34 AM Philip Thrift <cloud...@gmail.com> wrote:

>>> Other interpretations (but not MWI, as far as I can see) are used in writing programs for computational QM.

>> Like what?

> Multiple Histories.

And Multiple Histories uses path integral formulation and path integral formulation uses renormalization theory which is entirely in sympathy with the Shut Up And Calculate Interpretation; it's a wonderful way of getting the right answer, Feynman won a Nobel Prize for inventing it, but he was never entirely comfortable with it because it gave no coherent mental picture. He didn't even try to hide the imperfections in his idea.

And you have a wonderful many-worlds theory that avoids all infinities? And doesn't need renormalization?

Bruce

[Philip Thrift]

In any case, PIs are good for grad students:

Path Integrals in Quantum Physics R. Rosenfelder https://arxiv.org/abs/1209.1315 "lectures intended for graduate students who want to acquire a working knowledge of path integral methods in a heuristic, non-mathematical way for application in many diverse problems in quantum physics"

@philipthrift 

[John Clark]

On Thu, Oct 10, 2019 at 6:46 AM Bruce Kellett <bhkel...@gmail.com> wrote:

>>And Multiple Histories uses path integral formulation and path integral formulation uses renormalization theory which is entirely in sympathy with the Shut Up And Calculate Interpretation; it's a wonderful way of getting the right answer, Feynman won a Nobel Prize for inventing it, but he was never entirely comfortable with it because it gave no coherent mental picture. He didn't even try to hide the imperfections in his idea.

> And you have a wonderful many-worlds theory that avoids all infinities? And doesn't need renormalization?

The MWI needs renormalization just like its competitors, but nobody said many-worlds theory is the be all and end all and needs no improvement, but at least it provides a quantum-mechanical model however imperfect it may be. I think it's a important step toward a theory that is significantly less wrong. I am, of course, not sure of that.

John K Clark

John K Clark

 

[Bruce Kellett]

On Thu, Oct 10, 2019 at 10:09 PM John Clark <johnk...@gmail.com> wrote:

On Thu, Oct 10, 2019 at 6:46 AM Bruce Kellett <bhkel...@gmail.com> wrote:

>>And Multiple Histories uses path integral formulation and path integral formulation uses renormalization theory which is entirely in sympathy with the Shut Up And Calculate Interpretation; it's a wonderful way of getting the right answer, Feynman won a Nobel Prize for inventing it, but he was never entirely comfortable with it because it gave no coherent mental picture. He didn't even try to hide the imperfections in his idea.

> And you have a wonderful many-worlds theory that avoids all infinities? And doesn't need renormalization?

The MWI needs renormalization just like its competitors, but nobody said many-worlds theory is the be all and end all and needs no improvement, but at least it provides a quantum-mechanical model however imperfect it may be.

So, in accordance with the logic you used above to be dismissive of path integral methods, MWI is entirely in sympathy with the Shut Up And Calculate Interpretation? That, according to you, is the consequence of a method requiring renormalization.

I think it's a important step toward a theory that is significantly less wrong. I am, of course, not sure of that.

I'm glad to hear it. Perhaps you could be more tolerant of alternative views?

Bruce 

[Quentin Anciaux]

I didn't have time to look at it for now (I will), but could you resume her position and explain how considering an event has *multiple* *real* past histories provides a *one* world interpretation ?

Thanks;

 

 

Bottom line: multiple histories are cheaper than many worlds.

@philipthrift

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[John Clark]

On Thu, Oct 10, 2019 at 7:30 AM Bruce Kellett <bhkel...@gmail.com> wrote:

 

>> The MWI needs renormalization just like its competitors, but nobody said many-worlds theory is the be all and end all and needs no improvement, but at least it provides a quantum-mechanical model however imperfect it may be.

> So, in accordance with the logic you used above to be dismissive of path integral methods, MWI is entirely in sympathy with the Shut Up And Calculate Interpretation?

No, MWI is entirely unsympathetic with Shut Up And Calculate however it is needed at least for part of it, at least for now, but at least it's trying to find something better, the other ones have given up. And Many Worlds doesn't have to worry about why the Schrodinger wave equation behaves differently when it is being observed as the other interpretations must, Carroll explains why this is true in his hour long talk that nobody except me seems to have watched even though it's supposed to be the subject of this thread. And of course nobody but me has bothered to read his book, but everybody has an opinion about it.

>> I think it's a important step toward a theory that is significantly less wrong. I am, of course, not sure of that.

>I'm glad to hear it. Perhaps you could be more tolerant of alternative views?

I am tolerant of alternative views as long as they are not in conflict with experimental results, if several theories make the same prediction I'm not embarrassed to say I favor those with the fewest assumptions, and Many Worlds is very cheap with assumptions, yes that results in it being expensive in universes but in my opinion that's worth it. And some things are not views at all they're gibberish, I freely admit I have nothing but contempt for that. 

 John K Clark 

[Philip Thrift]

On Thursday, October 10, 2019 at 6:35:11 AM UTC-5, Quentin Anciaux wrote:

Le jeu. 10 oct. 2019 à 11:30, Philip Thrift <cloud...@gmail.com> a écrit :

On Thursday, October 10, 2019 at 2:40:53 AM UTC-5, Quentin Anciaux wrote:

Le jeu. 10 oct. 2019 à 09:34, Philip Thrift <cloud...@gmail.com> a écrit :

On Wednesday, October 9, 2019 at 3:59:50 PM UTC-5, John Clark wrote:

On Wed, Oct 9, 2019 at 4:55 PM Philip Thrift <cloud...@gmail.com> wrote:

> Other interpretations (but not MWI, as far as I can see) are used in writing programs for computational QM.

Like what?

John K Clark

Multiple Histories.

https://en.wikipedia.org/wiki/Multiple_histories  ?

So there are multiple "worlds", if multiple past histories are real.... so as you dislike MWI, what's different here for you to accept multiple past ? (because if each event has multiple *real* past then likewise it has multiple *real* future).

Quentin

--

All those moments will be lost in time, like tears in rain. (Roy Batty/Rutger Hauer)

That's one way to look at it.

In Fay Dowker's debate with a Many Worlder:

via https://www.imperial.ac.uk/people/f.dowker

In this public debate I argue that the path integral (or sum over histories) approach to quantum mechanics provides a One World interpretation

I didn't have time to look at it for now (I will), but could you resume her position and explain how considering an event has *multiple* *real* past histories provides a *one* world interpretation ?

Thanks;

 

 

Bottom line: multiple histories are cheaper than many worlds.

@philipthrift

I don't know how Adrian Kent, Fay Dowker, et all would put it, but:

We live on One World, but beneath the surface of One World lies a Sea of (the births and deaths of) Quantal Histories. 

@philipthirft 

[Brent Meeker]

On 10/10/2019 6:39 AM, John Clark wrote:

And of course nobody but me has bothered to read his book, but everybody has an opinion about it.

You keep posting that, but I've already posted that I have read Carroll's book, and I've watched his recent video.  I don't think QM is the last word, so it's not a good idea to draw a lot of far fetched conclusions...like infinitely many universes in which everything happens.  Reconciling QM and GR may very well impose some bound on an QM probabilities and those might limit the "worlds" to quasi-classical one we live in.  Also MWI doesn't actually provide a physical mechanism for the "splitting"; decoherence combined with Zurek's envariance provides a partial mechanism but it leaves open questions like whether the split "propagates" at less than light speed or is instantaneous because it happens in Hilbert space.  Carroll cops out by saying either one works...which is what Bohr would have said. 

Brent

[John Clark]

On Thu, Oct 10, 2019 at 5:16 PM 'Brent Meeker' via Everything List <everyth...@googlegroups.com> wrote:

>> And of course nobody but me has bothered to read his book, but everybody has an opinion about it.

> You keep posting that, but I've already posted that I have read Carroll's book,

Sorry, I missed that.

>  I don't think QM is the last word,

Neither do I and neither does Carroll.

> so it's not a good idea to draw a lot of far fetched conclusions...like infinitely many universes in which everything happens. 

The trouble is to avoid that far fetched conclusion you must make some far fetched assumptions as I'm sure you know having read Carroll's book. Many Worlds is stripped down quantum mechanics devoid of all extraneous bells and whistles.  

> it leaves open questions like whether the split "propagates" at less than light speed or is instantaneous because it happens in Hilbert space.  Carroll cops out by saying either one works...which is what Bohr would have said. 

True, and the exact same thought occurred to me when I read that in Carroll's book...., well,... Bohr was the second greatest physicist of the 20th century so I guess it's not surprising if sometimes he makes a good point.

 John K Clark

[Bruno Marchal]

It is an economy of principles, especially with Mechanism, where there is no world at all, as there is only histories corresponding to the computations, which exists in all theories capable of explaining the existence of computer.

Bruno

@philipthrift 

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[Bruno Marchal]

If they use programs, they need an ontology in which all computations are realised, so the MWI is not an option, and QM-without collapse, that is Many “worlds” confirms that aspect which is unavoidable when we use any theory in which the notion of programs can be defined.

Bruno

@philipthrift

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[Bruno Marchal]

Then if you define a world by a set of events close for interaction, many histories implies the “usual many world”, but some called it one world, by equivocating the many-Histories with the One multiverse. It remains that if you look at the cat, your history will still differentiate.

Many-worlds and many-histories are slight variants of the same idea, and they are not even defined so precisely that we can differentiate them from the internal many-histories that we have in arithmetic or any Turing. Complete theory.

It is true that Mechanism makes the approach by Gelman and Hartle, or Griffith and Omnes more senseful, as with mechanism, there is no world” in the Aristotelian sense of “world” or “universe”. The states are epistemic, first person plural, notions.

Bruno

@philipthrift 

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[smitra]

On 10-10-2019 23:42, John Clark wrote:
> On Thu, Oct 10, 2019 at 5:16 PM 'Brent Meeker' via Everything List
> <everyth...@googlegroups.com> wrote:
>
>>>> And of course nobody but me has bothered to read his book, but
>> everybody has an opinion about it.
>>

>>> _You keep posting that, but I've already posted that I have read
>> Carroll's book, _
>
> Sorry, I missed that.
>
>>> _I don't think QM is the last word,_

>
> Neither do I and neither does Carroll.
>

>>> _so it's not a good idea to draw a lot of far fetched

>> conclusions...like infinitely many universes in which everything

>> happens. _

>
> The trouble is to avoid that far fetched conclusion you must make some
> far fetched assumptions as I'm sure you know having read Carroll's
> book. Many Worlds is stripped down quantum mechanics devoid of all
> extraneous bells and whistles.
>

>>> _ __it leaves open questions like whether the split "propagates" at

>> less than light speed or is instantaneous because it happens in
>> Hilbert space. Carroll cops out by saying either one works...which

>> is what Bohr would have said. _

>
> True, and the exact same thought occurred to me when I read that in
> Carroll's book...., well,... Bohr was the second greatest physicist of
> the 20th century so I guess it's not surprising if sometimes he makes
> a good point.
>

Indeed. The opposition to the MWI is not really motivated by the
technical details, people tend to oppose it because they don't like the
idea of "many words". Technical details are invoked but these apply just
as well to QM in general not just to MWI. The MWI could indeed be wrong
in a technical sense but that's then unlikely to strip the "many
worlds" aspect of it away.

This is similar to how Fred Hoyle vigorously argued against the Big Bang
theory. He didn't like it and as far as he was concerned it was all
baloney. He attacked the theory on the issue of the synthesis of the
elements. As originally proposed, all elements were supposed to have
been formed during the Big Bang. Hoyle realized that this couldn't have
been the case and he successfully developed the theory of stellar
nucleosynthesis. So, he did prove wrong the original version of the Big
Bang theory, but that didn't disprove the general idea of the Big Bang.

Saibal

[Brent Meeker]

On 10/11/2019 5:48 AM, smitra wrote:
>
> Indeed. The opposition to the MWI is not really motivated by the
> technical details, people tend to oppose it because they don't like
> the idea of "many words". Technical details are invoked but these
> apply just as well to QM in general not just to MWI. The MWI could
> indeed be wrong in a technical sense but that's then unlikely to 
> strip the "many worlds" aspect of it away.

Sez people who like the idea of multiple worlds.  Of course everyone
uses their intuition about what ideas to pursue.  But only advocates
perceive it as opposition.  Scientists perceive it as questioning.

Brent

[smitra]

One can indeed question the technical aspects of the MWI, like where the
Born is supposed to come from, but people tend to be motivated by
attacking the many world aspect of it, when that'something that can
equally well appear in other interpretations. For example, in collapse
interpretations of QM you are not guaranteed to not end up with a single
World. E.g. Copenhagen Interpretation in an infinite universe leads to a
de-facto MWI-like multiverse.

Saibal

[smitra]

Most people believe in either block time or presentism. Few people
believe that the past never really existed. One can, e.g. believe that
God created the universe ten minutes ago which would mean that all our
memories of events that took place earlier are false memories. The
universe came into being ten minutes ago including us with all our false
memories of the events that actually never happened. If we then assume
that the past and the future are/were/will be real (whatever that
means), then that defines a multiverse of Worlds labeled by the time
variable.

Saibal

[Brent Meeker]

That's just playing with words.  That's not what anybody means by
"multiple worlds" in either cosmology or quantum mechanics.

Brent

[spudb...@aol.com]

Sort of like the Boltzmann Brain thing where Bruno suspect is irrelevant. I don't mind irrelevancy, but do like the idea of the BB being,  Mr. God Sir!

https://www.thoughtco.com/what-are-boltzmann-brains-2699421

Saibal

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[Bruno Marchal]

On 14 Oct 2019, at 03:20, spudboy100 via Everything List <everyth...@googlegroups.com> wrote:

Sort of like the Boltzmann Brain thing where Bruno suspect is irrelevant. I don't mind irrelevancy, but do like the idea of the BB being,  Mr. God Sir!

https://www.thoughtco.com/what-are-boltzmann-brains-2699421

The BB requires many hypothesis, but they can illustrate the mind-body problem for physicalist.

Arithmetic emulates already all possible brains, Botzmann or not.

That can be proved in one line … from Gödel’s 1931 paper.

Bruno

-----Original Message-----
From: smitra <smi...@zonnet.nl>
To: everything-list <everyth...@googlegroups.com>
Sent: Sun, Oct 13, 2019 11:26 am
Subject: The multiverse almost everyone believes in

Most people believe in either block time or presentism.  Few people
believe that the past never really existed. One can, e.g. believe that
God created the universe ten minutes ago which would mean that all our
memories of events that took place earlier are false memories. The
universe came into being ten minutes ago including us with all our false
memories of the events that actually never happened. If we then assume
that the past and the future are/were/will be real (whatever that
means), then that defines a multiverse of Worlds labeled by the time
variable.

Saibal

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