A Principle Explanation of the “Mysteries” of Modern Physics

[PeterDonis]

That fact alone is used heuristically

This is probably where I see the disconnect.

First, as I think I've said before, I don't think "heuristically" is enough. You can't just assume the effect you want to be there actually is there in a solution that is applicable to a galaxy and our observations of it. You have to show that the effect is there and of the right general order of magnitude. Just assuming it's there because it appears to be there in a different solution is not enough.

Second, the "fact" you are talking about, even in the solution you explicitly examine (collapsing FRW surrounded by Schwarzschild vacuum surrounded by expanding FRW), is not an effect that produces what you are looking for, as you are describing it later in your post. More on that below.

The correction we proposed is simply to replace $M_L$ in the Newtonian acceleration with a corrected value, since the mass of the matter responsible for the acceleration is being measured in two different ways and GR allows for simultaneously differing mass values for one and the same matter

This is simply invalid handwaving. "GR allows for simultaneously differing mass values for one and the same matter" is not a magic wand. It's a specific statement about a specific pair of measurements, and it has a specific effect, and that effect is not what you're looking for.

A correct application of "GR allows for simultaneously differing mass values for one and the same matter" would look like this:

The mass $M_L$, because it is obtained from observed luminosities, is a sum of "locally measured" masses--masses that would be measured by an observer in the same local region of the galaxy as the stars whose luminosities are being observed. Those are the masses that appear in the mass-luminosity relationships that are being used.

The mass $M_R$, because it is obtained from observed rotation curves, is a sum of "externally measured" masses--masses that would be measured by an observer in the vacuum region outside the system. (There are some technicalities to this, but I think it's reasonable for the case under consideration.)

GR allows "externally measured" masses to be different from "locally measured" masses for systems like galaxies, because the latter include the effects of gravitational binding energy while the former do not. But that effect, as I've already noted, is in the wrong direction: "locally measured" masses are larger than "externally measured" masses, not smaller. So if the only matter in a galaxy is luminous matter, we would expect a GR correction to make $M_L > M_R$, which is the opposite of what we need. (Also, the magnitude of this correction is small; it is of rough order of magnitude $G M / c^2 R$, where $R$ is some appropriate value for the radius of the galaxy. For all galaxies we know of, this correction is a tiny fraction of a percent at best.)

GR also includes spatial curvature, which is not included in the standard Newtonian models of galaxies, but as I've already said, this does not affect either $M_R$ or $M_L$; it only affects our estimate of average density.

There is no other GR effect I know of that is applicable here. The only other thing you discuss in the paper that seems at all relevant is the claim on p. 5, after equation (7), that observers in the exterior FRW region will somehow measure $M_p$ instead of $M$; I have already explained why I don't find that claim to be valid. The only thing I would add to that here is that, as far as I can tell, any such effect, if it were valid, would affect how we infer $M_R$ from observations, not how we infer $M_L$; but you are saying in what I've quoted above that your claimed effect changes how we infer $M_L$.

We found a functional form for correcting $M_L$ that rivals or beats all competitors across three different astronomical matter distributions -- galactic, galactic cluster, and cosmological

As an empirical finding, this is fine. But it does not support any claim that there is a valid GR correction that will produce such a functional form. I don't see how there can be one, for the reasons given above. And as I've already remarked, and you have agreed, you are not deriving your functional form from any underlying GR equations; you are just assuming it as an ansatz and seeing how it fits the data. So the fact that it fits the data well does not provide any support for the claim that there is in fact a valid GR correction that leads to your ansatz.

So if your functional form turns out to be valid (i.e., if it doesn't turn out to be just another way of representing the effects of dark matter), I think it will be because it is a reasonable approximation to some underlying effect that is not present in GR, but is present in some modified theory (possibly derived from quantum gravity) that includes effects that are not present in GR. (I personally think this is extremely unlikely, but that's just my opinion; once we actually have a working theory of gravity, possibly quantum gravity, that goes beyond GR, we'll see what it says.)

 

[ohwilleke]

So it sounds like this is basically a discovery of an empirical formula that works well with broad applicability that is only dimly motivated by very top level concepts in GR, which doesn't mean that it isn't potentially a big deal, or that it might be possible to reverse engineer the formula to determine what kind of gravitational effect is necessary to produce this formula.

How does this compare to the works of Deur who derives a similar effect from the self-interactions of gravitons a naive effort to build a quantum gravity LaGrangian, more or less from first principles and informed by an analogy to parallel QCD equations (although his approach is not inherently quantum in nature and can also be described classically in terms of the self-interactions of a classical gravitational field)?

The formula seems very different but the result seems to be very similar.

 

[RUTA]

This is probably where I see the disconnect.

First, as I think I've said before, I don't think "heuristically" is enough. You can't just assume the effect you want to be there actually is there in a solution that is applicable to a galaxy and our observations of it. You have to show that the effect is there and of the right general order of magnitude. Just assuming it's there because it appears to be there in a different solution is not enough.

The judges at the Gravity Research Foundation, journal referees, and journal editors disagree with you there, as it received Honorable Mention and was published.

Second, the "fact" you are talking about, even in the solution you explicitly examine (collapsing FRW surrounded by Schwarzschild vacuum surrounded by expanding FRW), is not an effect that produces what you are looking for, as you are describing it later in your post. More on that below.

This is simply invalid handwaving. "GR allows for simultaneously differing mass values for one and the same matter" is not a magic wand. It's a specific statement about a specific pair of measurements, and it has a specific effect, and that effect is not what you're looking for.

A correct application of "GR allows for simultaneously differing mass values for one and the same matter" would look like this:

The mass $M_L$, because it is obtained from observed luminosities, is a sum of "locally measured" masses--masses that would be measured by an observer in the same local region of the galaxy as the stars whose luminosities are being observed. Those are the masses that appear in the mass-luminosity relationships that are being used.

The mass $M_R$, because it is obtained from observed rotation curves, is a sum of "externally measured" masses--masses that would be measured by an observer in the vacuum region outside the system. (There are some technicalities to this, but I think it's reasonable for the case under consideration.)

GR allows "externally measured" masses to be different from "locally measured" masses for systems like galaxies, because the latter include the effects of gravitational binding energy while the former do not. But that effect, as I've already noted, is in the wrong direction: "locally measured" masses are larger than "externally measured" masses, not smaller. So if the only matter in a galaxy is luminous matter, we would expect a GR correction to make $M_L > M_R$, which is the opposite of what we need. (Also, the magnitude of this correction is small; it is of rough order of magnitude $G M / c^2 R$, where $R$ is some appropriate value for the radius of the galaxy. For all galaxies we know of, this correction is a tiny fraction of a percent at best.)

GR also includes spatial curvature, which is not included in the standard Newtonian models of galaxies, but as I've already said, this does not affect either $M_R$ or $M_L$; it only affects our estimate of average density.

You've totally misunderstood what was published. Your analysis is so far off the mark, I would have to reproduce most of the paper to correct it here. Think carefully about your assertion, Peter. You're claiming that the authors, judges, referees, and editors all missed the fact that the application of the effect was backwards. But, it's obvious to you. Doesn't that give you pause at all?

There is no other GR effect I know of that is applicable here.

Is that your basis for a no-go theorem?

As an empirical finding, this is fine. But it does not support any claim that there is a valid GR correction that will produce such a functional form. I don't see how there can be one, for the reasons given above.

Unfortunately, the reasons given above are totally misguided.

And as I've already remarked, and you have agreed, you are not deriving your functional form from any underlying GR equations; you are just assuming it as an ansatz and seeing how it fits the data. So the fact that it fits the data well does not provide any support for the claim that there is in fact a valid GR correction that leads to your ansatz.

That is true.

So if your functional form turns out to be valid (i.e., if it doesn't turn out to be just another way of representing the effects of dark matter), I think it will be because it is a reasonable approximation to some underlying effect that is not present in GR, but is present in some modified theory (possibly derived from quantum gravity) that includes effects that are not present in GR. (I personally think this is extremely unlikely, but that's just my opinion; once we actually have a working theory of gravity, possibly quantum gravity, that goes beyond GR, we'll see what it says.)

Do you have any calculations or references to support your beliefs here? Because the reasons given above are totally erroneous. You have totally misunderstood the paper and I don't have the time to help you there, my friend.

 

[RUTA]

So it sounds like this is basically a discovery of an empirical formula that works well with broad applicability that is only dimly motivated by very top level concepts in GR, which doesn't mean that it isn't potentially a big deal, or that it might be possible to reverse engineer the formula to determine what kind of gravitational effect is necessary to produce this formula.

How does this compare to the works of Deur who derives a similar effect from the self-interactions of gravitons a naive effort to build a quantum gravity LaGrangian, more or less from first principles and informed by an analogy to parallel QCD equations (although his approach is not inherently quantum in nature and can also be described classically in terms of the self-interactions of a classical gravitational field)?

The formula seems very different but the result seems to be very similar.

I'll check that out, thnx.

 

[PeterDonis]

The judges at the Gravity Research Foundation, journal referees, and journal editors disagree with you there, as it received Honorable Mention and was published.

I don't accept arguments from authority. In fact, when I see someone retreat into an argument from authority, my Bayesian prior is to raise my estimate of the probability that their claims are mistaken. Just to help you calibrate your estimate of me, I posted a thread in the relativity forum not too long ago proposing that an argument by Schild that is presented in MTW is erroneous. The thread is linked below if you care to read it; there is quite a bit of good discussion by a number of PF members, several of whom raised good points I had not thought of:

https://www.physicsforums.com/threa...me-dilation-imply-spacetime-curvature.919181/

You've totally misunderstood what was published.

If that's the only response you can give, I'm afraid we have reached an impasse. But I'll try and frame a simpler question that might elicit a more helpful response from you in a follow-up post.

You're claiming that the authors, judges, referees, and editors all missed the fact that the application of the effect was backwards. But, it's obvious to you. Doesn't that give you pause at all?

No. I have no idea who these people are or what expertise they have in GR.

I won't respond to the rest of your post since I don't see any basis there for a constructive discussion. But, as I said, I'll try to frame a simpler question in a follow-up post.

 

[PeterDonis]

Here is my attempt at framing a simpler question. The following quote is from p. 5 of the paper:

The spacetime geometry of the surrounding FLRW dust will be unaffected by the intervening Schwarzschild vacuum, so observers in the surrounding FLRW dust (global context) will obtain the “globally determined” proper mass $M_p$ for the collapsed dust ball while observers in the Schwarzschild vacuum (local context) will obtain the “locally determined” dynamic mass $M$ for the collapsed dust ball.

The question is this: how will each of these observers obtain the masses they are said to obtain in the above?

I'll give what I understand to be the answer for the observer in the Schwarzschild vacuum region: this observer puts a test object into orbit about the "galaxy" (which in this model is actually a collapsing FLRW dust region, but let's ignore that and assume it's a stationary compact region like a galaxy) and measures its orbital parameters, and uses the well-known equations for orbits in Schwarzschild spacetime to derive the mass $M$ of the central object.

So to rephrase the question: first, is my understanding above correct? And if it isn't, what is the correct description of how the observer in the Schwarzschild vacuum region will measure his $M$?

And second, how will the other observer, the one in the surrounding FLRW dust region, measure $M_p$? What I am looking for is an explicit description of a measurement procedure similar to what I described above for the Schwarzschild observer. I have speculated about this in previous posts, but since you are saying I have misunderstood the paper, I will refrain from speculating. I would like you (@RUTA) to tell me.

 

[PeterDonis]

You've totally misunderstood what was published.

Btw, I should clarify something: nothing I have said should be taken as claiming that this statement just quoted is wrong. In fact I don't understand the claims being made in the paper about things like "globally determined" vs. "locally determined" mass, or how an observer in the surrounding FLRW dust region in what I quoted in my previous post just now can measure $M_p$. What I am trying to figure out is whether I don't understand because I've missed something, or because the paper is actually wrong in its claims about the existence of an effect within standard GR that has the necessary properties.

So far, the responses I have gotten have moved me in the direction of "the paper is actually wrong", but that's still just opinion on my part because I still have not gotten a response which helps me to make sense of the parts of the paper that I can't understand. In my previous post I tried to frame a simple question that focuses on one particular part that I can't understand, in the hope that I will get a response that helps me to understand it. I may still not agree with it even after I understand it, but I would much prefer, if I am going to end up disagreeing, to be able to do so with confidence that I understand the claim I am disagreeing with. That is why I have persisted in asking questions.

 

[PeterDonis]

How does this compare to the works of Deur

A more pertinent paper by Deur for this discussion might be this one:

https://arxiv.org/pdf/0901.4005.pdf

This is ref. 3 in the paper linked to in the quote above, and appears to be the original paper presenting his proposed effect and estimating its impact on galaxy rotation curves.

 

[RUTA]

Let me review the scholarly process at work here. We have a *community* of scholars who work in a particular field and they have "authorities," e.g., journal editors and contest judges. When you believe you have something of interest to this community, you write it up and submit it too that community's "judicial institutions," e.g., journals and contests. Other members of the community (your colleagues) vet your work and the authorities then decide if it should be disseminated or otherwise recognized. If you read something that has passed this vetting process and been distributed by this community and you feel it should be clarified or corrected, you write up your idea and subject it to the same process within that community. If your colleagues and the authorities agree, they distribute it to the community so everyone may benefit from your clarifications and/or corrections. I've worked on both sides of this process, i.e., I've had papers published and/or recognized and I've published refutations of publications. It's a long process and it takes lots of work.

You may not respect the authorities and/or your colleagues in the community, but you nonetheless have to get them to sign off on your ideas if you want your ideas distributed and/or recognized by that community. I understand PF only allows Insights based on ideas that have successfully passed this process. My Insight is based 100% on that process. I have not seen you post any references refuting anything in my Insight that have passed that process. All I've seen from you are value judgments and unsupported beliefs regarding what is a highly tangential point of the Insight, i.e., principle explanation in modern physics. For example, what do you think about the ScienceX News article I linked earlier?

If you can cite a no-go theorem having passed the scholarly process, you will save me a lot of time in the future. Otherwise, you're wasting a lot of my time responding to your unsupported beliefs and value judgments. I'm sorry, I just can't spare the time in that direction, Peter.

 

[RUTA]

I read the Deur arXiv paper and found it interesting. I would like to see their fits of X-ray cluster mass profiles, since that's where MOND fails miserably and MOND also works well with galactic rotation curves. I would like to see their fits of the type Ia SN data and the Planck CMB anisotropy data, since they claim to account for dark energy effects. The work is highly speculative of course, since it's based on a direct quantization of GR which we know doesn't work. But, at least it provides an exact functional form and that form might be approximately produced from whatever QG theory we ultimately obtain.

 

[PeterDonis]

Let me review the scholarly process at work here.

I am not trying to criticize or disparage the scholarly process. I am certainly not trying to claim that the journal should not have published your paper. That is entirely up to them. I am also not at all saying that your Insights article should not have been written or that PF should not have published it.

I am just trying to understand the heuristic argument you are making in the paper regarding the presence of a GR effect with the claimed properties. Lecturing me on the scholarly process does not help me with that at all. What would help me with that would be if you would answer the questions I posed in post #76. If you're not going to do that, I'll just bow out of the discussion since I have nothing further either to gain from it or to contribute to it.

 

[PeterDonis]

All I've seen from you are value judgments and unsupported beliefs

No, that's not all you have seen from me. You have also seen specific, simple questions from me. You have not answered my latest one, in post #76. Can you answer it?

regarding what is a highly tangential point of the Insight, i.e., principle explanation in modern physics

Most of what I have posted in this discussion has not been about that at all. It has been about the GR effect claimed in your paper which I have not been able to understand.

 

[PeterDonis]

You're claiming that the authors, judges, referees, and editors all missed the fact that the application of the effect was backwards.

You're misunderstanding my point here. I am not saying that the application of your claimed GR effect in the paper was backwards. I am saying that the only GR effect I can come up with that could apply to $M_L$, which is where you say the change needs to happen, is in the opposite direction from what it would need to be to resolve the issue your claimed effect is supposed to resolve. That observation in itself doesn't tell me that anything specific in the paper is wrong; it just tells me that, whatever your claimed GR effect is, if it exists, it can't be any of the ones I can come up with. Which is why I keep asking questions to try to help me figure out what your claimed GR effect is, since if it exists it must be something different from any of the ones I have come up with.

 

[PeterDonis]

The work is highly speculative of course, since it's based on a direct quantization of GR which we know doesn't work.

Actually, from what I can see, the effects described in the 2009 Deur paper I linked to, and the 2020 paper @ohwilleke linked to, are classical effects and should be present in a classical GR model. His investigation was motivated by considering graviton-graviton interactions in a quantum field theory of a spin-2 field, but the actual Lagrangian he presents in the 2009 paper is classical; it's just a power series expansion of the standard Einstein-Hilbert Lagrangian around a zero order flat metric.

It seems to me that there are basically two classical effects he is describing:

(1) Nonlinearity in the Einstein Field Equation, which leads to terms in a post-Newtonian expansion that amount to adding a $\ln(r)$ term to the Newtonian potential, which in turn adds a $1 / r$ term to the Newtonian force, which is basically the same thing that MOND does, but now without requiring any modification to GR;

(2) Non-sphericity, the fact that a galaxy is a flattened disc and not a sphere, which, according to Deur, prevents different nonlinear effects under #1 above from canceling out. If this is correct, it is very interesting, because it would mean that the effects he is talking about would not be visible in a spherically symmetric model of the sort I have been considering in framing the questions I've asked. Which unfortunately makes checking the whole thing a lot harder, since there are no known closed form solutions for the flattened disc case (which is why Deur has to rely on numerical simulations).

 

[PeterDonis]

I would like to see their fits of X-ray cluster mass profiles, since that's where MOND fails miserably and MOND also works well with galactic rotation curves. I would like to see their fits of the type Ia SN data and the Planck CMB anisotropy data, since they claim to account for dark energy effects.

These are good points, I would like to see the same things for Deur's proposed model.

 

[PeterDonis]

what do you think about the ScienceX News article I linked earlier?

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.

 

[ohwilleke]

I read the Deur arXiv paper and found it interesting. I would like to see their fits of X-ray cluster mass profiles, since that's where MOND fails miserably and MOND also works well with galactic rotation curves. I would like to see their fits of the type Ia SN data and the Planck CMB anisotropy data, since they claim to account for dark energy effects. The work is highly speculative of course, since it's based on a direct quantization of GR which we know doesn't work. But, at least it provides an exact functional form and that form might be approximately produced from whatever QG theory we ultimately obtain.

There is a complete annotated bibliography here.

 

[ohwilleke]

I would like to see their fits of the type Ia SN data and the Planck CMB anisotropy data, since they claim to account for dark energy effects.

One of the pieces of the @RUTA paper that I found particularly interesting was the CMB fit and I'm still trying to get a better handle on how that piece was done from a nuts and bolts perspective.

Deur has done some of what you are wondering about in his papers, although only at a back of napkin level.

But, Deur hasn't done the CMB piece. I corresponded with Deur about that and it turns out that the main reason is that he has a day job doing QCD physics at Jefferson Labs (some of his best work there is on bridging the boundary between non-perturbative and perturbative QCD methods), but has no funding for his gravity work (which is outside what is employer does and outside his subspecialty in physics) and he simply hasn't had the resources to do a big project like that in his spare time.

He did publish this week a detailed 117 page preprint spelling out his previous findings that apparently dark matter to ordinary matter ratios in elliptical galaxies are strongly correlated with the extent to which they are non-spherical using a decent sized sample, something that no other dark matter particle or modified gravity theory of which I am aware predicts, but which flows naturally from his approach as a prediction.

Deur's dark energy concept is very interesting because unlike almost all other dark energy theories it doesn't require any new substance and doesn't raise conservation of mass-energy issues the way that GR does which makes it particularly attractive in a potential quantum gravity theory.

Instead, he posits that the gravitational field of an object gets semi-confined within a system where dark matter phenomena are observed (much like gluons are largely confined within hadrons) and that this limits the amount of that object's gravitational field that escapes that system, thereby reducing the strength of the gravitational fields between systems. The weaker fields between systems look like dark energy. This explains why inferred total amount of dark energy estimates are of the same order of magnitude as inferred total amount of dark matter estimates (i.e. the coincidence problem).

Also, this means that unlike GR and most modified gravity theories, there is no need for a fundamental constant to quantify dark energy, so his approach actually has one less free parameter than GR with a cosmological constant (at least in principle).

 

[PeterDonis]

There is a complete annotated bibliography here.

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.

 

[PeterDonis]

there is no need for a fundamental constant to quantify dark energy, so his approach actually has one less free parameter than GR with a cosmological constant

This struck me when I was reading the article you linked to; I think this is a very nice feature of the model.

 

[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 $hf = E$.