I Question about discussions around quantum interpretations

[gentzen]

Oh, for goodness' sake. I'm sorry to sound blunt here, but if you feel cheated because you didn't think to look at the inside cover of the book before buying it, to me that's on you, not Feynman or Ralph Leighton.

I didn't buy the book, I read the copy from a public library. I don't remember whether I noticed that actually Leighton was the author. But I certainly remember that I was convinced that Leighton was a physicist and coauthor of the Feynman lectures. Maybe Preface and Acknowledgment of "QED: The Strange Theory of Light and Matter" were responsible for this:

If you are planning to study physics (or are already doing so), there is nothing in this book that has to be “unlearned”: it is a complete description, accurate in every detail, of a framework onto which more advanced concepts can be attached without modification. For those of you who have already studied physics, it is a revelation of what you were really doing when you were making all those complicated calculations!

This book purports to be a record of the lectures on quantum electrodynamics I gave at UCLA, transcribed and edited by my good friend Ralph Leighton. Actually, the manuscript has undergone considerable modification. Mr. Leighton’s experience in teaching and in writing was of considerable value in this attempt at presenting this central part of physics to a wider audience.

When I read those words again, your comment about the publishers came to my mind:

Not to mention that it couldn't have been just Leighton: the publishers of the book had to know how it was written, and they listed Feynman as an author.

At least for QED, listing Feynman as one of the author was certainly mandatory. And here too, listing Feynman as one of the author was probably mandatory. In fact, Angela Collier says in the video that there are tape recordings (they are even on the internet), and that according to James Gleick the stories in the book roughly correspond to those tapes, but heavily filtered. Not listing Ralph Leighton as author is the fishy part. Both books appeared 1985, QED is probably the one which appeared first. Maybe not being listed as author on the stories book was Ralph's revenge for being denied authorship of QED?

For a critique of her treatment of Feynman from someone who was in a much better position than she to know relevant facts, see this:

https://www.feynmanlectures.caltech...Baez_regarding_Angela_Colliers_sham_video.pdf

Michael Gottlieb is a friend of Ralph Leighton, and also has other conflicts of interest. Hence, it is unfortunate that he wrote: "In closing I will mention that Angela is making money from publishing this poisonous trash." Overall, my impression is that he is simply bad at coping with that stuff, but not acting in bad faith. I'm not convinced by his:

She gives false and misleading information about other books too, claiming, for example, that all the stories in Feynman’s autographical books are lies, without giving any basis for that claim, other than her speculations.

Angela did give evidence, for example from James Gleick and Murray Gell-Man. And his

the exercises were originally published in the 1960s, by Feynman and his coauthors

doesn't fact check either: Feynman was not listed as author when the excercises were originally published in the 1960s. But he is listed as author in Michael Gottlieb's publication. And of course, attacking John Baez before even trying to contact Angela Collier was not wise either:
John Baez (1/2):

... where Angela Collier will ruthlessly dissect the mythology he built around himself. You probably won't agree with everything she says, and you may hate some of it, but it will still be thought-provoking.

John Baez (2/2):

I was not implicitly endorsing all of @acollierastro's claims in my first post. I merely said what I wanted to say.

Nor am I implicitly endorsing Gottlieb's claims here. I hope Gottlieb and Collier can discuss this without using me as an intermediary.

Still, Michael Gottlieb somehow managed to convince me that Angela Collier guesses at the motivations of Ralph Leighton, Michael Gottlieb, and other "self appointed coauthors" of Feynman are off. What drove this home for me was
Blake C. Stacey

I'll go ahead and disagree with Collier's take on the *Feynman's Lost Lecture* book. The Goodsteins give *more* and *more accurate* credit than Feynman did.

(But her analysis of the stories in Leighton's book is not affected by this.)

 

[PeterDonis]

I was convinced that Leighton was a physicist and coauthor of the Feynman lectures.

Robert Leighton was a physicist and coauthor of the Feynman lectures. His son Ralph Leighton was not, nor did he ever claim to be. Again, this doesn't look to me like a case of anyone trying to deliberately mislead; it looks like a case of you not being very careful.

I'm not going to bother arguing any further about Angela Collier's claims. Both of us have given some references, and other readers can make up their own minds, and it's off topic for this thread anyway.

 

[RUTA]

Here is a 2023 paper relevant to this thread Many-Worlds: Why Is It Not the Consensus?

Abstract:​

In this paper, I argue that the many-worlds theory, even if it is arguably the mathematically most straightforward realist reading of quantum formalism, even if it is arguably local and deterministic, is not universally regarded as the best realist quantum theory because it provides a type of explanation that is not universally accepted. Since people disagree about what desiderata a satisfactory physical theory should possess, they also disagree about which explanatory schema one should look for in a theory, and this leads different people to different options.

 

[bhobba]

Just a quick question to Ruta.

First, I always enjoy your posts, and this is a nice one, especially for helping out a newbie from a different area, sociology.

My question is, do you think QFT with the field considered real a realist interpretation?

Thanks
Bill

 

[RUTA]

Just a quick question to Ruta.

First, I always enjoy your posts, and this is a nice one, especially for helping out a newbie from a different area, sociology.

And also to you :-)

My question is, do you think QFT with the field considered real a realist interpretation?

Thanks
Bill

I'm not a philosopher, my philosophy colleague and coauthor Michael Silberstein handles these kinds of questions, but naively my answer is "yes". Many (most?) in foundations believe quantum fields are the fundamental building blocks of reality. I don't see how you can get any more "real" than that, but I may not appreciate the philosophical nuance.

 

[ojitojuntos]

Thank you for the replies in this thread! I'll check the various sources you've recommended, although it will probably take me a while haha
I also wanted to clarify that I'm aware that the laws of physics are not emergent in the same sense as social structures and dynamics are. When I mentioned that as a sociologist accepting stochasticity as inherent to reality was easier, I meant from a epistemic point of view, but I'm not equating social dynamics to physics; I know that these are very different areas of knowledge.

Related to this, I'm having some trouble understanding a couple of concepts: I understand that the wavefunction evolves deterministically once you have the measurement; however, what we observe is that, before the measurement, reality looks inherently probabilistic, and that this represents the measurement problem, which quantum interpretations try to solve, right?

Now, at the effective scale of human experience, even if we assume a probabilistic interpretation of quantum, does this make a difference? Or am I wrongly assuming a barrier between the quantum and classical?

 

[PeterDonis]

the wavefunction evolves deterministically once you have the measurement; however, what we observe is that, before the measurement, reality looks inherently probabilistic, and that this represents the measurement problem, which quantum interpretations try to solve, right?

I think you have it somewhat backwards.

In a typical quantum experiment, we prepare a system, it goes through some kind of process, and then we measure it. Preparing the system determines the starting wave function; the wave function then undergoes unitary evolution (which is deterministic) through the process in the middle, and only when we measure at the end do any probabilities come into play.

As an example, take the Stern-Gerlach experiment (or at least an idealized version of it). We prepare a spin-1/2 particle in a definite state, say spin-z up. Then we pass it through a Stern-Gerlach magnet oriented in, say, the x direction. Doing that induces a unitary (i.e., deterministic) evolution of the state. Then we measure the particle with a detector screen downstream of the S-G magnet: here we have one of two possible results, corresponding to two different places where the particle could hit the screen: one place corresponds to a measurement result of spin-x up, the other corresponds to a measurement result of spin-x down. There is a 50% probability of each result; that's the only place where probability comes into play at all.

The measurement problem, in the context of the experiment just described, is this: the state of the particle after it goes through the S-G magnet is a superposition of spin-x up and spin-x down (actually it's an entangled superposition, with the particle's spin being entangled with the direction of its momentum--the two different momentum directions point at the two different spots on the detector screen). How is it that when we measure the particle, we don't measure any such superposition, but instead, we measure either spin-x up or spin-x down? Or, to put it another way, why do we measure only one spot on the detector screen where the particle hits, instead of two? What is it about the screen that makes the particle just have one measurement result?

 

[bhobba]

Or, to put it another way, why do we measure only one spot on the detector screen where the particle hits, instead of two? What is it about the screen that makes the particle just have one measurement result?

Nutting things out for yourself is a great way to learn.

I could give my answer; however, central to this whole thing is something called Gleason's Theorem:
https://arxiv.org/pdf/quant-ph/9909073

Please take a moment to read it, put your thinking cap on, and see what emerges on the other side.

Post any thoughts here.

Thanks
Bill

 

[RUTA]

The measurement problem, in the context of the experiment just described, is this: the state of the particle after it goes through the S-G magnet is a superposition of spin-x up and spin-x down (actually it's an entangled superposition, with the particle's spin being entangled with the direction of its momentum--the two different momentum directions point at the two different spots on the detector screen). How is it that when we measure the particle, we don't measure any such superposition, but instead, we measure either spin-x up or spin-x down? Or, to put it another way, why do we measure only one spot on the detector screen where the particle hits, instead of two? What is it about the screen that makes the particle just have one measurement result?

Here are options for answering questions like this from Allori's paper linked in post #103:

Some theories are what Einstein [3] called constructive theories. For one thing, these theories have a microscopic ontology, which constitute the building blocks of everything else. Constructive theories allow one to understand the phenomena compositionally and dynamically: macroscopic objects are composed of microscopic particles, and the macroscopic behavior is completely specified in terms of the microscopic dynamics. Therefore, the type of explanation these theories provide is bottom-up, rather than top-down. According to Einstein, there is another type of theory, which he dubbed principle theory. Theories of this type, also called kinematic theories, are formulated in terms of principles, which are used as constraints on physically possible processes: they exclude certain processes from physically happening. In this sense, principle theories are top-down: they explain the phenomena identifying constraints the phenomena need to obey to. They are ‘kinematic’ theories because the explanations they provide do not involve dynamical equations of motion and they do not depend on the interactions the system enters into. Instead, by definition, constructive theories involve dynamical reductions in macroscopic objects in terms of the motion and interactions of their microscopic three-dimensional constituents. Flores [4] argued that this distinction could be expanded in terms of framework theories, which deal with general constraints, and interaction theories, which explicitly invoke interactions. He thought that framework theories are principle theories while interaction theories include a larger set of theories than constructive theories. Furthermore, he connected framework theories with unification and interaction theories with mechanistic explanation (see also [5,6]).