Insights A Principle Explanation of the “Mysteries” of Modern Physics

[PeterDonis]

doesn't raise conservation of mass-energy issues the way that GR does

Can you elaborate on this?

 

[ohwilleke]

I'm a little confused by this statement in the article:

"Deur's approach does not reproduce the conclusions of conventional classical General Relativity in the weak gravitational fields and spherically asymmetric systems where it dark matter and dark energy phenomena are observed"

At least as regards the effects I described in post #84 (particularly the first one), I don't see how this is correct. AFAIK it is perfectly true that conventional models of galaxies, the ones in which the discrepancy between mass inferred from luminosity and mass inferred from rotation curves is observed, are Newtonian and do not include any post-Newtonian terms, which means they do not include any effects of nonlinearity in the EFE. Those post-Newtonian terms and nonlinear effects are certainly present in principle, and in this respect Deur simply seems to be arguing that, contrary to the assumption underlying conventional models, those effects are not in fact negligible for galaxies. Since the magnitude of those effects is extremely hard to estimate from first principles (it's not feasible to numerically solve the Einstein-Infeld-Hoffman equations for a system of $10^{11}$ bodies), the arguments underlying the conventional assumption that they are negligible are heuristic, and so proposing a model that challenges those assumptions does not strike me as being inconsistent with GR.

Some of the other effects mentioned (such as the confinement invoked to account for dark energy effects) are not, as I understand it, present at all in classical GR, so the article's remark would apply to those; but the article doesn't seem to be drawing any distinction of this kind, it just seems to be making a blanket statement that none of Deur's claimed effects are present in classical GR, and that seems to me to be too strong.

I've seen some statements in for example, Misner and Thorne's textbook "Gravitation", to the effect that self-interactions of a gravitational field cannot be an independent source of gravitational effects, that gravitational energy cannot be localized, and other details that don't seem to be consistent with Deur's approach. They look like no go theorems inconsistent with his approach but that may simply over read what they really mean.

A phrase that I like to use is that Deur's approach is different than GR as conventionally operationalized. All of his assumptions are plain vanilla in any attempt to quantize gravity from a GR foundation (which motivates his research method and makes his approach more obvious, even though, as you correctly note and one of his later papers explains, there is nothing in his conclusions that is inherently non-classical).

Deur also uses a scalar approximation of what are really tensor fields, so that it is possible to do the math, but makes a good case that this approximation for calculation purposes doesn't impact the result very much in systems that are close to equilibrium.

I've seen several papers arguing that GR should have very few post-Newtonian effects at the galaxy and larger scale, but agree with you that these conclusions aren't very rigorous.

 

[ohwilleke]

Can you elaborate on this?

While mass-energy is conserved locally in GR, there is debate over whether the cosmological constant amounts to violation of conservation of mass-energy as the amount of dark energy increases when the volume of the universe does, or whether that is really a trade off between gravitational potential energy of some sort and dark energy. You probably understand that debate better than I do.

Deur's approach, because it doesn't have a cosmological constant which is the only mass-energy conservation violating term in GR, has both local and global conservation of mass-energy. Dark energy phenomena arise from a lack of gravitational energy holding galaxies together in his approach since the energy that would do that is used to create dark matter phenomena instead, not from something extra pulling them apart, relative to the no cosmological constant conventionally applied GR status quo.

This is good for a quantum gravity theory because in a quantum gravity theory you'd like to have everything arise locally and no global effects like the cosmological constant. If you can fit all phenomena into the action of your graviton, you have a much easier problem.

 

[PeterDonis]

there is debate over whether the cosmological constant amounts to violation of conservation of mass-energy as the amount of dark energy increases when the volume of the universe does, or whether that is really a trade off between gravitational potential energy of some sort and dark energy

That debate isn't just over the dark energy case, although that's the case Sean Carroll chose to use to illustrate the issue in his blog post about "energy is not conserved". The debate applies to any spacetime that is not stationary, including the many non-stationary spacetimes with no cosmological constant (such as all of the FRW spacetimes with no cosmological constant).

So while I agree that not having to have a cosmological constant is a nice feature, I don't think Deur's model "solves" any general problem about "mass-energy not being conserved in GR". The same problem, if you think it's a problem, is there in FRW spacetime with no cosmological constant, which is basically where Deur's model would end up as a model of the universe as a whole (modulo some corrections due to the other effects in his model, that also don't affect the "conservation" issue as far as I can see).

This is good for a quantum gravity theory because in a quantum gravity theory you'd like to have everything arise locally and no global effects like the cosmological constant.

The cosmological constant in GR is not "global"; it's just non-dynamical--it's an extra effective energy density that is just there regardless of anything else that happens. In quantum field theory it just corresponds to a nonzero vacuum expectation value of energy, which is a perfectly good local quantity.

The last sentence leads to what I think is a better way to describe what problem is solved by not having to have a cosmological constant. All attempts to estimate from QFT what a nonzero vacuum expectation value of energy should be, if there is one, come up with answers 120 or so orders of magnitude larger than the observed value they are supposed to be explaining. Deur's model makes that problem go away, which is certainly nice, but again, I don't think "solving a problem with mass-energy not being conserved" is a good way to describe why it's nice; "eliminating the problem of the huge mismatch between theoretical and experimental values of the cosmological constant" would be better.

 

[PeterDonis]

I've seen some statements in for example, Misner and Thorne's textbook "Gravitation", to the effect that self-interactions of a gravitational field cannot be an independent source of gravitational effects, that gravitational energy cannot be localized, and other details that don't seem to be consistent with Deur's approach. They look like no go theorems inconsistent with his approach but that may simply over read what they really mean.

The bolded phrase is correct. I wrote up a series of Insights articles on this very topic:

https://www.physicsforums.com/insights/does-gravity-gravitate/

The short version is, the answer to the title question (does gravity gravitate?) can be either yes or no, depending on how you interpret it. The things MTW is talking about are part of the interpretation of the question that leads to a no answer. But the way Deur is using nonlinear effects is part of the interpretation of the question that leads to a yes answer. Both interpretations are valid; they just show that the question itself as originally stated is ambiguous, and the ambiguity can be resolved into two different questions that have different answers.

 

[Jimster41]

The Tsirelson bound is the most QM can violate the Bell inequality known as the CHSH inequality. Classical physics says the CHSH quantity must reside between $\pm 2$, but the Bell states give $\pm 2 \sqrt{2}$ (the Tsirelson bound). Superquantum correlations respect no-superluminal-signaling and give a CHSH quantity of 4. So, quantum information theorists want to know "Why the Tsirelson bound?" That is, why doesn't Nature produce superquantum correlations? Our answer is "conservation per NPRF." Of classical, QM, and superquantum, only QM satisfies this constraint.

I had heard of CHSH but there was a lot in that answer I didn't understand at all. In fact I hadn't even heard of "superquantum correlations". This paper was a pretty good intro to the idea... in case it's valuable to anyone else.

Maybe those variables are hidden by the 5D aliens so we won't realize there is no such thing as time and will keep trying to make lots of important decisions (that's a joke, in case it's not clear).

https://arxiv.org/abs/1205.1162
Classical, quantum and superquantum correlations
GianCarlo Ghirardi, Raffaele Romano

A deeper understanding of the origin of quantum correlations is expected to shred light on the physical principles underlying quantum mechanics. In this work, we reconsider the possibility of devising "crypto-nonlocal theories", using a terminology firstly introduced by Leggett. We generalize and simplify the investigations on this subject which can be found in the literature. At their deeper level, such theories allow nonlocal correlations which can overcome the quantum limit.

 

[RUTA]

I had heard of CHSH but there was a lot in that answer I didn't understand at all. In fact I hadn't even heard of "superquantum correlations". This paper was a pretty good intro to the idea... in case it's valuable to anyone else.

Maybe those variables are hidden by the 5D aliens so we won't realize there is no such thing as time and will keep trying to make lots of important decisions (that's a joke, in case it's not clear).

https://arxiv.org/abs/1205.1162
Classical, quantum and superquantum correlations
GianCarlo Ghirardi, Raffaele Romano

You might also like to read this Insight which explains an "unreasonable consequence" of superquantum correlations as presented in Bub and Bub's book.

I'm not surprised you haven't heard of superquantum correlations. I started working in foundations in 1994 and didn't hear about superquantum correlations until 2018. We published a book on foundations of physics in 2018 and Jeff Bub asked us to give a talk on it for his seminar. After a few hours of discussion we were walking from the restaurant to our car when Bub said, "What I really want to know is, Why don't we observe superquantum correlations? They don't violate no-superluminal-signaling, so why are they not found in Nature?" Silberstein and I didn't know what he was talking about. Answering his question (they violate "conservation per NPRF") is what ultimately led to this Insight.

 

[RUTA]

I'm not sure about all aspects of the analogy between SR and QM that is described in the paper.

I agree that all observers in relativity having to measure $c$ for the speed of light, regardless of their state of motion, is analogous to all observers in QM having to measure $\pm \hbar / 2$ for spin, regardless of their choice of measurement direction. And I agree that the latter fact requires that, when analyzing conservation of angular momentum in QM, the best we can possibly do is the "average conservation" that the paper describes.

I'm not sure how length contraction or time dilation correspond to the spin "corrections" that have to be made to verify "average conservation", since length and time aren't conserved quantities and the contracted lengths and dilated times that a given observer assigns to objects in motion relative to him are not "corrections" applied to any calculation of conservation.

I'm wondering, though, if the latter issue could be addressed by looking at energy and momentum instead of time and length, since they are "corrected" by the same factors and they are conserved quantities. That would still leave as a difference between SR and QM the fact that the SR conservation laws are not average only.

The "conservation part" of the mystery of entanglement is not found in the mysteries of time dilation and length contraction. The fact we are pointing out in our Scientific Reports paper (as outlined in the ScienceX News article) is that all of these mysteries stem from the application of the relativity principle ("no preferred reference frame" NPRF) to a fundamental constant. And while this principle explanation of the mysteries is true (principle explanation = mathematical consequences of empirical facts), there are still no (consensus) constructive accounts. And these mysteries are very very old. So, what do we make of these facts?

As I suggest in the ScienceX News article, perhaps we don't always need an explanation based on a causal mechanism. That's where the ScienceX News article ends, but we go further in our Scientific Reports paper. There we suggest that principle explanation is just as valid as constructive explanation when physics is viewed per Mermin's QBism (cited therein):

Laws of science are the regularities we have discerned in our individual experiences, and agreed on as a result of our communications with each other. Science, in general, and quantum mechanics, in particular, impose further constraints on my probabilistic expectations. They help each of us place better bets on our subsequent experience, based on our earlier experience.

In other words, physics provides constraints on experience. If that's the way you view physics, then a constraint such as NPRF is very reasonable. That's where the Scientific Reports paper ends, but we go further in our Entropy paper. In that paper, we provide a mathematical model of consciousness whereby all of physics follows from two axioms (empirical principles), one of which is NPRF. And that shows how the mysteries of physics are related to the hard and combination problems of consciousness, and how neutral monism resolves them all. The bottom line: the physics we have is beautifully coherent and comprehensive (although not finished, since we still need quantum gravity of course).

 

[Jimster41]

The whole “average conservation of angular moments only, due to Quantuum fintude (h)” just keeps reminding me of this book “Evolutionary Dynamics” by Nowak.

I just opened it to the chapter (6) that sort of blew my mind because it showed how a stochastic Moran process (conservation and “abundance of individuals given by integers”) will lead through neutral drift to the extinction of all but one type. This just sounded so much like spontaneity symmetry breaking to me - I stopped reading the book.

I am hung up on how evolution, a dynamical view if ever there was, and the ultimate bully idea of dynamical time fits into the adynamical Lagragian description of things in your view?

IOW given your focus on physical constants as “discrete limits” can the resolution of simultaneity in 4D be imagined as an evolutionary process... or more importantly, can that be flipped and can evolution as a dynamical perception be imagined as the partitioning of NPRF spacetime you allude to? It seems to me a handy bridge.

Sorry, I’m still reading your book. It will take awhile. And I don’t want to lose this question. BTW the above is not my idea I got it from Eric Chaisson’s (“The Life Era: Cosmic Selection and Conscious Evolution” Harvard University Press). Fair warning, it’s a wild book, the Chaisson one. The Nowak book is this elegant and slightly horrifyingly clear textbook.

 

[RUTA]

I am hung up on how evolution, a dynamical view if ever there was, and the ultimate bully idea of dynamical time fits into the adynamical Lagragian description of things in your view?

Dynamical explanation in physics is still absolutely legit in our view, it's just not fundamental. In my opinion, anything that can be explained dynamically should be, since our experience is dynamical. I only resort to the more fundamental principle/adynamical/Lagrangian explanation as a last resort, e.g., in dealing with closed timelike curves, origin of the universe, delayed choice, etc. All this is covered in our book, as you'll see. Chapters 7 & 8 cover the reconciliation of our dynamical experience of time with adynamical or block universe physics. You can also read our Entropy paper. At 35 pages it's long, but still shorter than Chapters 7 & 8

 

[Jimster41]

"Here is how Weyl himself puts it: Physics is the “Construction of objective reality out of the material of immediate experience” ([34], p. 117)... Weyl is basically suggesting that spacetime is just the relationships or possible relationships between POs and their perceptions. What is called “objective reality” is what is common to all POs at least in potentia, and mathematical physics is just the codification of those relationships. It should be understood that the focus here is on various invariances across the perceptions of POs and the various adynamical global constraints on those perceptions that enforce those invariances. As Eddington puts it, “physics is about the world from the point of view of no one in particular” ([34], p. 195). Thus, physics is about all the possible perspectives of all POs and their perceptions. For example, consider the role of tensors in GR and their relationship to coordinate systems."

"...As Weyl put it, “The explanation of the law of gravitation thus lies in the fact that we are dealing with a world surveyed from within” ([34], p. 117). Keep in mind that the beauty of neutral monism is that talk about POs and their perceptions should be understood not as some sort of positivism, or some brand of idealism (subjective or otherwise), or merely as bracketed phenomenology, but in terms of James’ “instant field of the present” and what Russell calls “events”. That and that alone is what spacetime is."

This is all great stuff, and generally I buy it. Easy peasy. I remember liking William James back in school. The part I'm struggling with is whence "construction" of the TTO graph. Why and how - the contrast between the flow experience of PO's that make up that TTO graph/network and the "God" perspective over the graph (ironically a perspective gained over flow by said PO's). Why is GR expressed as "Tensor" relations rather than "how happy that all the PO's are just atoms is motionloess diamond". I don't think you can have the cake of "we examine from within and thus experince tensor-flow" and eat it too ala "we examine from without and see some completed construction of a TTO graph". These are both from PO's right. How so? Is the contrast in some sense unreal, or is it non-dual. The graph is both constructed but not constructed. Maybe it's a graph of cats.

So, I am trying to get my head around the gauge-fixing part of the results from axioms. It seems relevant to the tension I am trying to describe. Just pretending for a second that there are all kinds of PO's not just people (or are people (with the ability to reflect upon and discuss the tension of consistency across TTO's somehow priveledged in the TTO graph vs. say rocks or muons) and being radically democratic with radical empiricism, say you have a couple of atomic PO's deep in the gravity well of the sun. This sun is cranking away with heat, pressure, gravity, geodesic stress - a regular hotbed of tension between said PO's so these two atomic PO's, say a couple of He atoms, are arguing long and loud. What happens next?

I have the similar confusion with Alice and Bob for that matter. After all you are saying conservation only on average... so sometimes Bob get's the final h (Alice must simply agree) sometimes Alice get's it. Poor Bob. How is that represented in the TTO model? Is that the source of, a description of, this PO vs. PO contention that I would argue...is ubiquitous. And this is an important connection for me... to the beautiful description of evolution... as fundamental... that I got from Chaisson and Nowak (edit: Let me add Manfred Schroeder's "Chaos, Fractals and Power Laws: Minutes from an infinite paradise" to that list - for explaining how similarity can be almost perfectly confused with symmetry),

 

[Jimster41]

Yeah, this is the part I want to be able to understand... and even though I aced calc three I am struggling to understand what "divergence free" means.

"For example, Einstein’s equations of GR (Gαβ=8πGc4Tαβ) are divergence-free (▽αGαβ=0 and ▽αTαβ=0), which means you have local conservation of energy-momentum—what flows into a region of space accumulates there or flows out. This is germane to the identification of a TTO through time."

How can both Alice and Bob occupy divergence free bubbles when trying to decide some maximally minuscule interaction by trading h's? And aren't there real concerns over "what goes in stays in or leaves through the boundary" when it comes to extreme geodesic contention, like the black-hole boundary-thing?

 

[Jimster41]

"The TTOs of classical physics interact per quantum physics, so the quantum exchange of energy-momentum between TTOs per QM must be consistent with their divergence-free nature..."

Okay, that was a pretty interesting paragraph I almost followed. Still I am bothered by the idea of gauge fixing and divergence free relations. Something has to give somewhere - some torsion has to exist in that graph and I get that the constraints want it to go to zero but that basically means - it isn't zero, and are there constraint violations - as with there are with every (real) empirical optimization I've ever seen?

Love this tho, "As noted by Rovelli, “Gauge is ubiquitous. It is not unphysical redundancy of our mathematics. It reveals the relational structure of our world” ([26], p. 7). In addition to the action for the Schrödinger, Klein–Gordon, and Dirac equations, this relationally defined K appears in the Maxwell and Einstein–Hilbert graphical actions and can be extended to the graphical action for the Standard Model of particle physics [41]."

 

[Jimster41]

"No, the early universe is only part of the entire 4D spacetime manifold that also contains classical spacetime regions with stars, dust, gas, planets, telescopes, and detectors, and these TTOs then provide the necessary classical (enduring) objects for the quanta associated with the early universe."

This to me seems consistent with evolution being fundamental. "Evolution" is definitely an awkward word because it is sooo loaded with dynamical connotation. What I liked about Chaisson's exotic proposal is the way it suggested evolution in 4D as just... sort of a big description of the constrained graph from hot dense beginning through locally driven complexity toward full dissipation (or something). It sounds dynamical but doesn't have to be from the "God's eye" view (that sounds religious, but isn't meant to). Anyway I'm sort of interpreting that as what you are alluding to above.

But I have questions about your statement that quantum PO's are not TTO's. You seem to say all TTO's are fundamentally contextualized quanta. The chain you describe above seems to suggest a cut - where what TTO's consist of aren't TTO's, they need the TTO's to... give them context (this definitely reminds me of Chaisson but it's been awhile since I read him).

I know this is way more question than you can respond to, suffice to say I'm enjoying the article and it's helping motivate interest in the book. I will definitely appreciate the multi-part, multi-level explication of ... once I get there.

 

[RUTA]

There is no "cut" in principle (although I'm guessing there are technical limitations) meaning QM allows for quantum momentum exchanges (interactions) of any size. No matter the size of the quantum exchange -- the momentum, spatial extent, and temporal duration involved -- the action is h for that interaction, since $hf = E$.

 

[RUTA]

We argue that the quantum momentum exchanged in an interaction does not itself interact with the collection of shared, self-consistent information constituting the block universe. That is, it does not have a worldline in the block universe. If it did, then you would need quantum exchanges for the quantum exchanges, since interaction is what establishes worldlines. And where would it end?

 

[RUTA]

Gauge invariance is related to conservation principles as we show in our example. I don't have any shorter way to say it than I did there. It's really just Zee's presentation (see reference therein) with our interpretation added. We're not suggesting a need for any new physics here, just a different way to view the (very successful) physics we already have.

 

[RUTA]

So, I am trying to get my head around the gauge-fixing part of the results from axioms. It seems relevant to the tension I am trying to describe. Just pretending for a second that there are all kinds of PO's not just people (or are people (with the ability to reflect upon and discuss the tension of consistency across TTO's somehow priveledged in the TTO graph vs. say rocks or muons) and being radically democratic with radical empiricism, say you have a couple of atomic PO's deep in the gravity well of the sun. This sun is cranking away with heat, pressure, gravity, geodesic stress - a regular hotbed of tension between said PO's so these two atomic PO's, say a couple of He atoms, are arguing long and loud. What happens next?

POs are not necessarily human, they can be actual or hypothetical data collection devices, e.g., the probe that just landed on an asteroid or a hypothetical probe of some spacetime location inside a star.

I have the similar confusion with Alice and Bob for that matter. After all you are saying conservation only on average... so sometimes Bob get's the final h (Alice must simply agree) sometimes Alice get's it. Poor Bob. How is that represented in the TTO model?

Both Alice and Bob always measure h ($\pm \frac{\hbar}{2}$ to be precise) for their spin measurements of the Bell spin state in question. Both are justified in saying the other is the one who has to average their outcomes to obtain the "correct" value of spin to satisfy conservation of spin angular momentum. Just like time dilation and length contraction where Alice(Bob) tells Bob(Alice) that his(her) clocks are slow and his(her) meter sticks are short, both are right. That is the "weird" consequence of conservation per NPRF, i.e., the relativity principle applied to the measurement of h.

 

[RUTA]

All of this talk about neutral monism (aka "radical empiricism") does sound a bit "wiggy" for sure. But, foundations opened the door for this with interpretations like QBism. For example, Mermin writes:

QBism takes more seriously than do most physicists the basic notion of empiricism, that all knowledge derives from experience. For a QBist empiricism has a strongly personal flavor to it: the knowledge of each one of us derives from our own personal experience. This is close to what William James called “radical empiricism”.

(cited in our in our Scientific Reports paper and attached here). We reject the subjective nature of QBism, opting instead for one, self-consistent objective account of physical reality (represented by the block universe of shared, self-consistent classical information). And it makes perfect sense given that we're advocating for the fundamentality of principle explanation, i.e., principle explanation doesn't necessarily require a constructive counterpart. If you believe physics is in the business of identifying constraints on experience, as QBism claims, then the constraint "no preferred reference frame" is quite reasonable without a corresponding causal mechanism.

 

[Jimster41]

We argue that the quantum momentum exchanged in an interaction does not itself interact with the collection of shared, self-consistent information constituting the block universe. That is, it does not have a worldline in the block universe. If it did, then you would need quantum exchanges for the quantum exchanges, since interaction is what establishes worldlines. And where would it end?

Thank you for the answers! This one clarified things a good bit. I saw that sentence and wondered... if it was a fast one. But, it sounds consistent with persuasive QM Interpretation arguments I've heard saying there is no "there" there without observation, quanta are just models of the rules of observation, and there is no way to claim they exist outside of observation... Not a bad thing. And consistent with the the background W. James non-dual stuff, the observer observing from within the observed etc. Plus I hat infinite regress.

I still struggle with what entropy (or "Energy Rate Density" Chaisson) both high and low is doing in all this. I get it is subject to the constraints and fits in. Part of why this is bugging me is because stuff you are saying is making me think I can put that piece in the puzzle better. Why (and how) does it just happen to describe the shape of the 4D block? Whence that slope? Maybe you are saying it is a principle explanation and doesn't need a constructive account (fair enough), or that it already has one (called biology and chemistry - even more fair they are awesome), But emergent complexity still just leaves me scratching my head. Why? How? Why not just monotonic dissipation. To use your terms... why isn't the "block universe of shared, self-consistent classical information" just shared at coordinate zero. Why such a mess... of a time (for lack of a better word) getting to the other end.

Not saying you were referring to Chaisson but I have heard him called Wiggy (or similar). For my part I think he is a pretty serious physicist and natural philosopher (with an actual reputation to boot) and I enjoyed reading his ideas. I think they are relevant and occupy a gap between physics and biology that needs more monism. It's a gap I certainly don't see a lot of light in - and like I said the (you et al) ideas of NPRF and neutral monism (axioms and results) are tantalizing new terms/clarifications in the context of this questioning (for me anyway).

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

I will keep reading all this great stuff as time allows. Thank you.

 

[David Spector]

Putting SR aside for a moment, if we consider what could be "incomplete" about QM, there is one obvious candidate: the proposal in 1952 by David Bohm that the initial positions of the particles of an experiment be considered part of the definition of the experiment.

What evolves from this proposal is a clear understanding that the Schrödinger equation describes completely the geometry of the experiment and how that geometry affects particle trajectories (or spin directions or photon polarization).

But this equation, the wave function, is a limited view, one that spawned the 1927 Bohr Interpretation that is still accepted today that enshrines several aspects of the tiny regime to mystery in the form of axioms: the Born Rule, duality between particle and wave, superposition of particles, the indeterminacy of particle trajectories prior to measurement, and the collapse of the wave function, at least.

We obtain a "completing" of QM by simply including the initial positions of the particles. This, plus the idea that the Schrödinger equation be treated as the primary force on the particles, yields deterministic trajectories for particles through the double-slit experiment and similar simplicity for other QM effects.

John Bell did more than just show that local "hidden-variables" theories are wrong, he showed that the Bohm nonlocal "hidden-variables" theory is right, and Bell supported Bohm as a result. What are these non-local "hidden variables"? Nothing more than simply the initial positions of the particles, as Bohm has been unique in stating.

Further confirmation of Bohm's interpretation of QM has come in the form of experiments that demonstrate the actual trajectories of individual particles between the single slit they go through to the screen. While the trajectories of an ensemble of particles are deterministic, the pattern they produce on the screen is the familiar "wave interference" pattern, which is so tempting to interpret as due to wave interference, when both slits are open, and the bar pattern when the unused slit is closed. What has changed by closing the slit? Just the wave function, which describes the experimental configuration. True, this is not classical physics and is false to our common sense, but remember that this is the regime of the very tiny, and things work differently due to its simplicity.

I think Einstein would have found Bohm's interpretation refreshing and in the spirit of a "completion" of QM, because it finally gives a deterministic basis in which a probability distribution is the emergent or computed result (rather than a mysterious axiom), just as the Maxwell-Boltzmann analysis based on molecular motion gives the temperature of a black body radiator as a probabilistic result, rather than as an experimental mystery.

 

[Jimster41]

@RUTA

I do sort of buy a little the problem of Bourne’s critique. The argument that “we need to be able to discuss real events” is in a sense claiming a privilege of observation.

i agree we do but still, feels like “saying simultaneity is subjectively or even objectively indefinite” would be not wrong.

not sure that would cause a problem for your BU or help make the case.

But then maybe one could argue that it can’t be if it is definite for at least one observer.

lord this is painful logic.

 

[RUTA]

Putting SR aside for a moment, if we consider what could be "incomplete" about QM, there is one obvious candidate: the proposal in 1952 by David Bohm that the initial positions of the particles of an experiment be considered part of the definition of the experiment.

I think Einstein would have found Bohm's interpretation refreshing and in the spirit of a "completion" of QM, because it finally gives a deterministic basis in which a probability distribution is the emergent or computed result (rather than a mysterious axiom), just as the Maxwell-Boltzmann analysis based on molecular motion gives the temperature of a black body radiator as a probabilistic result, rather than as an experimental mystery.

The problem with Bohm is the use of a preferred frame. This looks a lot like the situation Einstein found himself in (quote from forthcoming in Am. J. Phys. by Moylan):

The point is that at the end of the nineteenth century, physics was in a terrible state of confusion. Maxwell's equations were not preserved under the Galilean transformations and most of the Maxwellian physicists of the time were ready to abandon the relativity of motion principle [3], [4]. They adopted a distinguished frame of reference which was the rest frame of the ``luminiferous aether,'' the medium in which electromagnetic waves propagate and in which Maxwell's equations and the Lorentz force law have their usual forms. In effect they were ready to uproot Copernicus and reinstate a new form of geocentricism.

Even "Einstein was willing to sacrifice the greatest success of 19th century physics, Maxwell’s theory, seeking to replace it by one conforming to an emission theory of light, as the classical, Galilean kinematics demanded" before realizing that such an emission theory would not work (J. Norton, “Einstein’s Special Theory of Relativity and the Problems in the Electrodynamics ofMoving Bodies that Led him to it,” https://www.pitt.edu/~jdnorton/papers/companion.pdf). So, now that we know QM follows from the relativity principle applied to Planck's constant h, just like SR follows from the relativity applied to the speed of light c, (https://arxiv.org/abs/2106.12043), I have to believe Einstein would again defer to relativity principle :-)

 

[David Spector]

I am not aware that Bohmian Mechanics specifies a preferred intertial frame, the Ether. If you could provide a citation for this fact, especially in Bohm's 1952 paper, I would be very grateful. None of the rest of your comments appears to have any relationship to what I actually wrote. Quantum mechanics itself, to the best of my knowledge, does not "follow" from the existence of Planck's Constant, although it certainly makes use of it in the Schrödinger equation, which is the heart of QM. QM mostly "follows" the strange results seen in experiments involving the very tiny regime of electrons, photons, and even molecules. I do agree fully that SR follows from the constancy of c in all inertial frames.

 

[RUTA]

I am not aware that Bohmian Mechanics specifies a preferred intertial frame, the Ether. If you could provide a citation for this fact, especially in Bohm's 1952 paper, I would be very grateful. None of the rest of your comments appears to have any relationship to what I actually wrote. Quantum mechanics itself, to the best of my knowledge, does not "follow" from the existence of Planck's Constant, although it certainly makes use of it in the Schrödinger equation, which is the heart of QM. QM mostly "follows" the strange results seen in experiments involving the very tiny regime of electrons, photons, and even molecules. I do agree fully that SR follows from the constancy of c in all inertial frames.

dBB is non-local, i.e., it uses a faster-than-light causal mechanism (pilot wave). Thus, if you use dBB to explain Bell-inequality-violating QM correlations, you must pick a preferred frame to maintain definite causal ordering. It has nothing to do with the aether. This is a very common complaint against dBB, you can find it addressed in virtually every paper dealing with the dBB interpretation.

 

[David Spector]

Thank you kindly for your clarification. I'm afraid I don't see the need for faster-than-light causal mechanisms in nonlocal pilot waves, as in it particle trajectories are deterministic, and which Bell supported, according to Making Sense of Quantum Mechanics, Jean Bricmont, Springer, 2016.

If such complaints are indeed common, perhaps you could be so kind as to throw just one citation my way. You would clearly be more likely to find one than I, since you know them to be common, but I don't (I'm not a professional physicist).

I would be grateful to see a criticism of Bohm's 1952 proposal that actually has some merit. Recall that all of physics turned against him, along with his former friend Robert Oppenheimer, when Joseph McCarthy found out that Bohm had briefly been a member of the Communist Party. In my opinion, political issues should not be mixed with physics.

 

[RUTA]

Thank you kindly for your clarification. I'm afraid I don't see the need for faster-than-light causal mechanisms in nonlocal pilot waves, as in it particle trajectories are deterministic, and which Bell supported, according to Making Sense of Quantum Mechanics, Jean Bricmont, Springer, 2016.

If such complaints are indeed common, perhaps you could be so kind as to throw just one citation my way. You would clearly be more likely to find one than I, since you know them to be common, but I don't (I'm not a professional physicist).

I would be grateful to see a criticism of Bohm's 1952 proposal that actually has some merit. Recall that all of physics turned against him, along with his former friend Robert Oppenheimer, when Joseph McCarthy found out that Bohm had briefly been a member of the Communist Party. In my opinion, political issues should not be mixed with physics.

There are lots of references for the non-locality given in the Wiki article https://en.wikipedia.org/wiki/De_Broglie–Bohm_theory

 

[David Spector]

I have read this Wikipedia article, and it is surprisingly accurate: "The theory's explicit non-locality resolves the 'measurement problem', which is conventionally delegated to the topic of interpretations of quantum mechanics in the Copenhagen interpretation."

This supports my point of view, as I have expressed it here. The Copenhagen Interpretation says that we can say nothing until a measurement has occurred, and that measurement involves the "collapse" of the wave function, so that it no longer applies. The Copenhagen Interpretation enshrines ignorance in the name of physics by basing QM on a set of axioms that cannot be further understood. This is nonsense. To understand Nature, all of our assumptions must be investigated and eventually explained. Physics is a body of knowledge that works to describe existing and future experiments and observations. The Standard Interpretation of QM opposes this definition of physics. All that survives the terrible impact of the Standard Interpretation are the highly precise predictions of QM itself.

"De Broglie–Bohm theory was widely deemed unacceptable by mainstream theorists, mostly because of its explicit non-locality. Bell's theorem (1964) was inspired by Bell's discovery of Bohm's work; he wondered whether the theory's obvious nonlocality could be eliminated."

Bell's conclusion, based on the marvelous probabilistic thought experiment called "Bell's Inequality," was thst local "hidden variables" theories were incorrect, but that nonlocal "hidden variables" such as in Bohmian Mechanics worked fine. Bell explicitly wrote in support of Bohm's interpretation, as expressed in Bohm's very readable paper of 1952, A Suggested Interpretation of the Quantum Theory in Terms of "Hidden" Variables.

I agree that nonlocal influence, even happening at the speed of light in a vacuum or slower, is counter to our commonsense physics, based on our senses operating in our standard regime. But so what? Physics is not restricted to the standard regime, and much of our interest in physics explicitly concerns fundamental particles, whose size is tiny. If you are rejecting the very basis of quantum mechanics, nonlocality, I'm afraid I must disagree with you.

In the double-slit experiment, a single photon traveling through a slit appears to be affected by a separate slit, through which it does not travel. Any interpretation must explain this apparent nonlocal mystery of Nature. The Standard Interpretation waves its hands and talks nonsense about how a particle can behave as a wave. Bohmian Mechanics does away with such nonsense.

There is a widespread bias against Bohmian mechanics, and it is usually based on ignorance and doubt. I hope you have thought deeply about the physics and are not merely expressing an unexamined belief.

 

[RUTA]

In the double-slit experiment, a single photon traveling through a slit appears to be affected by a separate slit, through which it does not travel. Any interpretation must explain this apparent nonlocal mystery of Nature. The Standard Interpretation waves its hands and talks nonsense about how a particle can behave as a wave. Bohmian Mechanics does away with such nonsense.

There is a widespread bias against Bohmian mechanics, and it is usually based on ignorance and doubt. I hope you have thought deeply about the physics and are not merely expressing an unexamined belief.

In order to provide a "constructive" account of QM (as required for a proper "interpretation"), one will have to give up something cherished. That's what all the no-go theorems tell us. Since I love special relativity (I got my PhD in general relativity) and SR also lacks any constructive account, I have recently decided that I can live without a constructive account of QM as long as I can find a "principle" account of it as compelling as that for SR (relativity principle and light postulate). And, I have done so (explained in this Insight and others referenced therein). Indeed, this principle account of QM uses the same relativity principle applied to a different constant of Nature, h ("Planck postulate"). I'm content with that :-)

 

[David Spector]

I am certainly happy that you are content to find an explanation of QM that satisfies you. However, gently, I will point out to you that in this lengthy discussion you have not been able to present a clear explanation of how allowing h to be variable solves any problem in understanding QM, whereas I have explained clearly how simply accepting nonlocality (and the initial positions of particles) does indeed solve the basic mysteries that are encapsulated as postulates by the flawed Copenhagen Interpretation, about which you have not even said whether you accept it or not. If physics is going to really explain how Nature works, it must be clear and understandable, not just the "hit-and-run" game of stating a nonobvious principle and then running away. If you are playing a game with me, Ruta, I do not like it much.