Is There A Simple Dark Matter Solution Rooted In GR?

[ohwilleke]

TL;DR Summary

A recent Physics Insights article references peer reviewed articles that purport to explain all dark matter phenomena with a concept described as contextual mass in GR. Is this analysis sound?

Two Recent Papers Propose A Simply Tweak To How General Relativity (GR) Is Applied That Purports To Explain All Dark Matter Phenomena Motivated By A Version of GR and Quantum Gravity.

The pair of related papers with overlapping text and common authorship (cited below) were published after peer review in a low profile but legitimate academic journal, by professional academics who are non-specialists in their subfields, mostly in a low profile department. The papers are not particularly new (2015 and 2016 preprints, published in 2016 and 2018) and haven't gotten much attention in the field, but were just recently brought to my attention by a Physics Forums Insights article (these are references 23 and 24 on the Physics Forums Insights article) by one of the co-authors of these papers.

The papers are notable because they purport to explain basically all dark matter phenomena (galaxy rotation curves, cluster data, CMB peaks) with one fairly straight forward tweak regarding how mass should be evaluated in general relativity (in the authors' view) that deviates from the Newtonian approximation. The CMB prediction they make plotted against LCDM and the data, for example, is as follows:

The papers also address a fix to the dark energy question (which is largely independent of its dark matter fix), but I'll save that for another post.

The papers are:

W.M. Stuckey, Timothy McDevitt, A.K. Sten, Michael Silberstein, "The Missing Mass Problem as a Manifestation of GR Contextuality" International Journal of Modern Physics D 27(14), 1847018 (2018) arXiv:1509.09288

and

W.M. Stuckey, Timothy McDevitt, A.K. Sten, Michael Silberstein, "End of a Dark Age?" International Journal of Modern Physics D 25(12), 1644004 (2016) arXiv:1605.09229

The authors suggest that (1) the apparent mass-energy of something is observer dependent, and (2) start from an assumption, in the tradition of loop quantum gravity and kindred quantum gravity theories, that spacetime is fundamentally discrete at some fine grained level and that locality is an emergent property of spacetime that at a more fundamental level has points that are directly connected to each other that are not local, i.e. spacetime is "disordered" at a fundamental level (e.g. some small number of points have direct links to points in other galaxies).

Motivated by these observations, they used what they called Modified Regge Calculus (MORC) and "geometrically modify proper mass interior to the Schwarzschild solution" to tweak GR (or simply to correctly apply GR in a non-customary way) in an effort to explain dark matter phenomena.

The theoretical foundation and motivation for this approach doesn't appear to be terribly widely accepted, and does not appear to be terribly rigorously spelled out in the articles either. It appears that the operational method is really motivated by just an ansatz, rather than a full fledged theory derived from first principles.

But ultimately, the show stopper, much like in the case of MOND and other modified gravity theories (some of which the papers consider and compare to their approach) is not the theoretical motivation, but the phenomenological success of their quite simple to apply adjustment to the conventional GR (in the basically Newtonian approximation that is widely used as a baseline in this area of astrophysics).

Questions

Given the extraordinary claims made, it seems as if these papers deserves closer attention. If they really do work, they should be trumpeted widely. If they don't, it is important to know why.

Is my summary of these articles accurate? If not, please explain what I am getting wrong.

Is their analysis sound, and if not, why not? In particular, are they correctly comparing the data to their theoretical results (which is a big deal even if their theoretical justification for formulas that work so well is flawed)?

 

[jedishrfu]

Thanks for reducing this post down a bit. Hopefully, both @RUTA and @PeterDonis will get a chance to review and comment.

 

[PeterDonis]

Moderator's note: The link to the Insights article in the OP has been fixed (it now points to the comment thread for the Insights article instead of to Blogger).

 

[PeterDonis]

The papers are notable because they purport to explain basically all dark matter phenomena (galaxy rotation curves, cluster data, CMB peaks) with one fairly straight forward tweak regarding how mass should be evaluated in general relativity

This appears to be what ref. 24 in the Insights article is doing, but it does not appear to be what ref. 23 is doing. Ref. 23, as far as I can tell, is proposing a modification to GR based on the idea that the GR model of spacetime as a continuous manifold is only an approximation.

 

[PeterDonis]

This appears to be what ref. 24 in the Insights article is doing, but it does not appear to be what ref. 23 is doing.

Btw, if I am correct in this, it means that discussion of the two papers probably needs to occur in separate threads. Discussion of ref. 23, which is proposing a modification to GR, would be properly discussed in this subforum. But discussion of ref. 24, which purports to be an application of straightforward GR, but taking into account non-uniformity in the stress-energy tensor, would be properly discussed in the relativity forum.

 

[ohwilleke]

Moderator's note: The link to the Insights article in the OP has been fixed (it now points to the comment thread for the Insights article instead of to Blogger).

Thanks. My bad.

 

[ohwilleke]

This appears to be what ref. 24 in the Insights article is doing, but it does not appear to be what ref. 23 is doing. Ref. 23, as far as I can tell, is proposing a modification to GR based on the idea that the GR model of spacetime as a continuous manifold is only an approximation.

arXiv noted that the two papers had substantially overlapping text in addition to common authorship. As far I can tell, both parties are using the same operational solution but motivating it differently. But, I may not be following them correctly.

 

[mfb]

Do they make any testable prediction for future measurements (that deviates from standard GR)?

 

[ohwilleke]

The predictions deviate from standard GR (the author appears to basically argue that this is because others are cutting corners in doing a GR based analysis and not considering the right things in their GR analysis, rather than saying that it is actually different from GR itself). The analysis discusses rotation curves, clusters and the CMB. They don't differ materially from the data, and from dark matter and other modified gravity solutions in the rotation curves, or from dark matter in the CMB, to the limits of observational accuracy.

The cluster result is different than MOND and (maybe) closer to CDM.

But, apparently there are fitting processes used and it doesn't actually flow from first principles. The common thread at the insights forum has a good discussion going mostly between the author and PeterDonis probing details.

The papers do not explore meaningfully predictions of any phenomena that should exist and have not been observed, or any phenomena that would discriminate between different dark matter phenomena explanations.

 

[PeterDonis]

The predictions deviate from standard GR.

More precisely, if we are talking about ref. 24, the predictions differ from the standard models for galaxy rotation curves, which use the Newtonian approximation to model the galaxies. That paper claims that its models are "standard GR", just using an aspect of it that the Newtonian approximation ignores.

 

[RUTA]

Sorry, I did not receive a notice of all these postings here. The last posting I saw said (I thought) that this thread was going to be closed. Peter asked that I stop in and clarify something about the two papers being discussed, i.e., are both or either of these papers based on GR proper?

In our paper "End of a Dark Age?" we posited disordered locality associated with a discrete underlying Regge graphical structure as giving rise to modifications to the predictions of idealized GR solutions over a continuous spacetime manifold. We acknowledged in our CQG paper (Stuckey, W.M., McDevitt, T., and Silberstein, M.: Modified Regge Calculus as an Explanation of Dark Energy. Classical and Quantum Gravity 29, 055015 (2012)) that indeed you don't have to posit any underlying mechanism for our fit of the type Ia SN data other than simple perturbation theory. In other words, that fit could really be understood as a perturbed GR solution (although we obtained our value for H from a Regge calc model with large links so ... ). I would definitely classify this paper as "modified GR," since (among other things) we used Regge calc with large links to obtain H, for example. The "Dark Age?" paper was published in 2016 which means it represents work done as early as 2014 (the CQG paper was posted in 2011 for example). So, our views have changed since then.

Closer to what we would advocate now (although work done over 5 years ago) is the paper "The Missing Mass Problem as a Manifestation of GR Contextuality." There we simply checked a functional form to account for "missing mass" in galactic rotation curve data, galactic cluster mass profile data, and CMB anisotropy data. We were able to meet or best several competitors with a very simple functional form, which is the take-home message of that work. That paper is compatible with GR proper, indeed we even used standard GR adjoined solutions to motivate the idea (although the exact functional form with fitting parameters was not obtained via GR, which is where the work needs to go).

The point I was trying to make in the Insight had nothing to do with the problems of dark energy or missing mass per se. The point was simply that all this work was motivated by our work in foundations, where we have argued for quantum-classical contextuality and that "screened-off" quantum systems do not have worldlines in spacetime (a form of direct action, our most recent papers are here or a shorter version here). Indeed, advocates of direct action (Davies and Feynman for example) gave it up when they realized it would be difficult to implement in curved spacetime. That motivated me to look for some anomalous astronomical data associated with the exchange of photons over astronomical distances. The type Ia SN data was perfect and was easily accounted for perturbatively with the added bonus of a great H value using Regge calc with large links. The missing mass problem followed first along these lines ("Dark Age?") and then via the notion of contextuality in the second paper. After we realized that time dilation, length contraction, Bell state entanglement, and the Tsirelson bound were all based on "no preferred reference frame" and published those papers, I wrote the Insight (and a couple others). That's where we're at today.

Hope this clarifies the situation :-)

 

[PeterDonis]

@RUTA, thanks very much for the clarification on the two papers.

Based on @RUTA's post and my previous remarks, I am closing this thread. Further discussion of the "End of a Dark Age" paper, if desired, should be done in a new thread in this forum, focused on the particular claims and methods in that paper. Further discussion of the "Missing Mass Problem" paper, if desired, should be done in a new thread in the relativity forum (or in the comment thread on the Insights article referenced, which already has some discussion of it).