Also be advised...

It is incorrect that String Theory is the only consistent context in which MOND can arise. While DGP and Cascading gravity did arise in a String Theory context; any theory with a higher-dimensional origin or precursor provides a similar benefit or effect, given the right initial assumptions. I have seen presentations by several non-ST researchers, claiming to reproduce or mimic MOND.

But I think de Rham's idea of long-distance degravitation is worthy of study. I see it as likely that the dimension of spacetime has changed over time, as you will read in my essay when it posts, and lately I'm working with a bimetric hypothesis where dimensionality is undefined at the outset (in the Planck domain), with both lower and upper limits, and then settling on a single value by the current era.

More later,

Jonathan

Of course,

Looking to Cosmology for clues might not be needed, if the Mandelbrot-G2 conjecture can be proved. Briefly; I'll summarize. It is conjectured that there is a non-trivial connection between Cartan's rolling ball model for G2 and the shape of the Mandelbrot Set, when extended into higher dimensions. Since Kricker and Joshi showed that the Mandelbrot Set helps map non-associative regions in the octonionic quadratic, and Giulio Tiozzo proved the monotonicity of entropy in M; it should be a slam dunk once that conjecture is proved, to a method for collapsing the String Theory landscape.

Just a thought...

Jonathan

"It is incorrect that String Theory is the only consistent context in which MOND can arise." There might be many consistent theories that imply MOND, but my guess is that string theory is the only plausible possibility for quantum gravity.

According to John H. Schwarz, "... string theory requires supersymmetry ..."

"Introduction to Superstring Theory" by John H. Schwarz, arXiv, 2000

My guess is that string theory with the infinite nature requires supersymmetry and dark-matter-compensations-constant = 0, but string theory with the finite nature hypothesis requires dark-matter-compensation-constant = (approximately) (3.9±.5) * 10^-5 and supersymmetry does not occur in nature.

If string theory with the finite nature hypothesis (as I envision it) is wrong, then it seems to me that the only plausible candidate for a new paradigm in the foundations of physics is string theory with supersymmetry and some form of the string landscape. Clearly, Milgrom thinks that I am wrong about string theory with the finite nature hypothesis -- if he thought that I am correct then he would immediately publicize the concept of the dark-matter-compensation-constant. So far as I know, everyone (except me) believes that the 4 ultra-precise gyroscopes malfunctioned as alleged by the Gravity Probe B science team. Milgrom has presented a brane-world approach to MOND.

"MOND from a brane-world picture" by Mordehai Milgrom, arXiv, 2018

I think that Milgrom's thinking about string theory is wrong. I am 100% convinced that Milgrom is the Kepler of contemporary cosmology, but I have severe doubts about him as a string theorist. If the Gravity Probe B science team is correct about the 4 ultra-precise gyroscopes, then I think that everyone should ignore all of my speculations about string theory -- I leave it to the string theorists to find the explanation for the empirical successes of MOND.

I don't have a beef with String Theory...

But I do have problems with the dogmatic approach of some of its practitioners. For the record; my copy of a green paperback by Green, Schwarz, and Witten is well worn, visible on the shelf from where I sit, and gets pulled out from time to time when I have deep questions. I especially like the intro by Witten on the lasting importance of dual theories, which was a motivating factor for developing the theory in the first place.

I am nowhere close to being an expert, but I did actually meet Ed Witten on my 59th birthday, when I also sat at the same table with Brian Greene. Unfortunately; I never got to meet Nima Arkani-Hamed, who was supposed to sit next to me. And since that time; I attended lectures by Marolf, Maldacena, Myers, and Strominger (among others). So I have at least gotten an overview from informed sources.

My recently-departed Physics mentor thought that String Theory was inevitably true but inconsequential unless researchers discover how it links back to everyday Physics in the known universe. This is along the lines of comments by Steinhardt, whom I met at FFP11 in Paris, back in 2010; and which I largely agree with. This kind of leads back to my earlier comment.

I am kind of wary of latching on to SUSY as a fundamental aspect of reality, especially after John Ellis's recent comments. I had a conversation with Frank Potter a number of years ago where he said that any number of unified theories could be concocted, that produce the Standard Model spectrum of particles, but also give us something else. His theory based on the Monster Group added another quark family, which has not been seen.

Not only Garrett Lisi, but also F.D. Tony Smith used E8 as a symmetry generator to derive a similar result. Tony claimed the LHC results validated his work by showing a triad of energy states for the Higgs. Unfortunately; Tony is no longer around to argue his theory. And another departed colleague Ray Munroe used both the Lie groups and simplicial geometry to create yet another theory with so called mirror-Fermions, which nobody is even looking for.

I think you may need to broaden your horizons.

All the Best,

Jonathan

I followed your link 'fredkin milgrom'...

I have encountered similar ideas in a different context. I had a lovely conversation with Gerard 't Hooft at FFP10 back in 2009, regarding his theory of quantum gravity based on cellular automata, which may be of interest. I brought up "Rechnender Raum" and the atoms of space idea, and then asked him "what does the calculating?" his theory. His reply was very interesting, because he said that Planck bits or atoms of space are not necessary, because the laws of nature do the calculating for us.

He also made some comments about the difficulty with obtaining Lorentz invariance in any CA based formulation. I was absolutely amazed, however, when he came back to this in his lecture at FFP11 where he devoted 4 slides to the discussion of the desirability of Lorentz invariance in a theory and the basis for the complication that makes this endeavor a difficult thing to do. I have thought about octonionic CAs, but I need a little more familiarity with the theory of permutahedra and associahedra to crack that nut.

More later,

Jonathan

p.s. - I left another comment above, now hidden. - jjd

    If Maldacena, Marolf, and Myers developed an idea together...

    Maybe it would be called MMM-theory.

    All the Best,

    Jonathan

    "... the difficulty with obtaining Lorentz invariance in any CA based formulation ..." My guess is that, at the Planck scale, Lorentz invariance fails, along with the concepts of spacetime, energy, and quantum information. At the present time, my thinking is as follow: (1) String theory is the mathematics of quantum gravity -- beyond a reasonable doubt. (2) Green, Schwarz, and Witten are in the same ballpark as Feynman, Schwinger, and Tomonaga -- beyond a reasonable doubt. (3) Milgrom is the Kepler of contemporary cosmology -- beyond a reasonable doubt. Am I overconfident about string theory? Am I overconfident about (non-relativistic) MOND?

    Consider the following article:

    "Free Will in the Theory of Everything" by Gerard 't Hooft, 2017, arxIv

    't Hooft's 2017 article seems to reveal no understanding about the importance of Milgrom's MOND. Here is what I think: There are 3 levels of physical reality: Level 1. Classical field theory. Level 2. Quantum field theory. 3. String theory with the infinite nature hypothesis, or string theory with the finite nature hypothesis. String theory with the infinite nature hypothesis, together with supersymmetry and D-branes, can provide mathematical models for any plausible, or implausible, physics. String theory with Wolfram's cosmological automaton predicts dark-matter-compensation-constant = (3.9±.5) * 10^-5 and the empirical validity of the Riofrio-Sanejouand cosmological model. There is an important synergy between string theory with the infinite nature hypothesis and string theory with the finite nature hypothesis because of mathematical embeddings and physical intuition about strings.

    I'll entertain that last possibility for now...

    And I do hold your idols in high regard. Not sure they have an inside track, however. I just read a comment on Sabine's blog about both 't Hooft and Wolfram's view being a non-starter because both space and time are discrete. Go figure. I'll keep an open mind and consider this explanation along with other possibilities. I found some other interesting articles in the Bekenstein memorial volume the Milgrom article is from. I'm not ruling out some possibilities yet, but explanation is needed if they fly. Let's say I have some favored ideas of my own too.

    More later,

    Jonathan

    My impression is that, as of the beginning of February 2020 C.E., both 't Hooft and Wolfram fail to realize that Milgrom is the Kepler of contemporary cosmology -- 't Hooft and Wolfram have some of the correct concepts but they have not appreciated the ideas of Milgrom, Riofrio, Sanejouand, and Pipino. MOND is data-based -- according to Kroupa, non-relativistic MOND is remarkably successful. The Riofrio-Sanejouand cosmological model is data-based. Riofrio published her model in 2004. By studying the same data, Sanejouand independently arrived at the model.

    Sanejouand, Yves-Henri. "A simple varying-speed-of-light hypothesis is enough for explaining high-redshift supernovae data." arXiv preprint astro-ph/0509582 (2005)

    What do I mean by the term "Einstein-Riofrio duality principle"?

    In string theory with the infinite nature hypothesis, the assumption is that, after quantum averaging, Einstein's field equations are 100% correct. Can the ΛCDM model be empirically refuted?

    Lambda-CDM model, Wikipedia

    By using supersymmetry, D-branes, and D-brane charges, my guess is that mathematical models of dark matter particles and the inflaton field can be cleverly adjusted to match any plausible, or implausible, physics.

    My guess is that the string theorists have discovered the "Einstein" part of Einstein-Riofrio duality. In the "Riofrio" part of Enstein-Riofrio duality, there are 3 modifications to Einstein's field equations: cutoff for minimum wavelength, cutoff for maximum wavelength, and

    dark-matter-compensation-constant = (3.9±.5) * 10^-5. Furthermore, the inflaton field is redefined: Guth's inflaton field is replaced by a inflaton field that is defined in terms of the Riofrio-Sanejourand model.

    I think some of those things have already been explored...

    Using D-branes and D-brane charges is what DGP gravity and Cascading DGP is, so Pourhasan, Afshordi, and Mann's idea of a 5-d black --> 4-d white hole might implement that, go along with VSL and you get something like what Afshordi and Magueijo came up with.

    Standard inflation may not be able to give you what you want, by varying parameters, but if it could Steinhardt thinks this is a pathology, because it fails to yield a single consistent picture. He is not a fan of having a String Theory landscape either, unless we also have a strategy at the ready to sub-select for physically realistic options.

    One would wish for a formulation where it falls out of the model, rather than requiring adjusting parameters. Using the Mandelbrot Set for a guide suggests options like the above noted theories, but it only works out if there are no adjusting factors applied. The pure form of M already describes a scenario like DGP but has no need to adjust brane tension and so forth.

    In fact; it suggests there was torsion on the fabric - as well as tension - which Joy Christian and Fred Diether say is what gave us the spectrum of particles we see. I.e. spin fields and trapped spin in the fabric (torsion) in the early universe produce spinor particles in the current day, according to their model. There is a lot to explore. It's hard for me to keep up.

    Best Wishes,

    Jonathan

    Or you could add Milgrom too...

    Then it would be MMMM-theory.

    Sorry couldn't resist,

    Jonathan

    Just another thought...

    What if the speed of light is a measure of the universe's mass? I we imagine there was a matter-free regime in the radiation dominated early universe; perhaps this translates into a higher light speed. By taking Einstein's venerable equivalence equation, and flipping terms to solve for c, We obtain c^2 = E/m, then let m --> 0 and discover c^2 is unbounded in a universe devoid of mass.

    I interpret this to mean the speed of light is infinite in the 2-d regime near the Planck scale as postulated by many Quantum Gravity theories. But it also might reproduce exactly the effect Sanejouand was talking about - assuming more matter congeals out of energy over time. My essay focuses on a mechanism to do exactly that. Perhaps we are more on the same page than you imagine.

    All the Best,

    Jonathan

      "What if the speed of light is a measure of the universe's mass?" The preceding question, according to my speculation, is the essential question in deciding between string theory with the infinite nature hypotheis (dark matter particles) versus string theory with the finite nature hypothesis (no dark matter particles). If dark-matter-compensation-constant = zero, then my guess is that the Riofrio-Sanejouand model is wrong. If the Riofrio-Sanejouand model is empirically valid, then my guess is that, during each Planck time interval, gravitational energy is transferred from the boundary of the multiverse into the interior of the universe -- implying that the mass-energy of our universe is related to the average speed of light in intergalactic space.

      According to Peebles, "The evidence for the dark matter (DM) of the hot big bang cosmology is about as good as it gets in natural science."

      Peebles, P. James E. "Dark matter." Proceedings of the National Academy of Sciences 112, no. 40 (2015): 12246-12248.

      My understanding of the evidence is that Kroupa is correct about dark matter particles and Peebles is wrong -- but perhaps dark matter particles with weird MONDian properties might be discovered.

      My guess is that string theory is empirically irrefutable. According to Schwarz, "... we explored whether it is possible to interpret the massless spin 2 state in the closed-string spectrum as a graviton. This required carrying out an analysis analogous to the earlier one of Neveu and Scherk. This time one needed to decide whether the interactions of the massless spin 2 particle in string theory agree at low energy with those of the graviton in general relativity (GR). Success was inevitable, because GR is the only consistent possibility at low energies (i.e., neglecting corrections due to higher-dimension operators), and critical string theory certainly is consistent. At least, it contains the requisite gauge invariances to decouple all but the transverse polarizations. Therefore, the harder part of this work was forcing oneself to ask the right question. Finding the right answer was easy. In fact, by invoking certain general theorems, due to Weinberg ... , we were able to argue that string theory agrees with general relativity at low energies ... . Although we were not aware of it at the time, Tamiaki Yoneya had obtained the same result somewhat earlier ... Scherk and I proposed to interpret string theory as a quantum theory of gravity, unified with the other forces. This meant taking the whole theory seriously, not just viewing it as a framework for deriving GR and Yang-Mills theory as limits."

      Schwarz, John H. "The early history of string theory and supersymmetry." arXiv preprint arXiv:1201.0981 (2012)

      Consider 2 viewpoints (A & B) concerning string theory: Viewpoint A. If an individual string could be measured, then a stringy generalization of Heisenberg's uncertainty principle would be revealed. Spacetime is doomed in terms of mathematical symmetries of the string landscape. At the Planck scale, there is curling up of extra special dimensions. An electron is a wave-particle possibility that probabilistically propagates through spacetime. Measurement is something that experimental physicists do. Strings are geometric completions of quantum probability amplitudes. After quantum averaging, Einstein's field equations are 100% correct. Viewpoint B. An individual string cannot in principle be measured. String vibrations are entirely virtual. Heisenberg's uncertainty principle is empirically valid whenever and wherever measurement can occur. Spacetime is doomed in terms of Wolfram's cosmological automaton (which is defined by 4 or 5 simple rules). At the Planck scale, there are no extra spatial dimensions -- string vibrations are confined to 3 copies of the Leech lattice. An electron is an approximate, computational possibility that discontinuously, computationally propagates in the interior of the multiverse generated by Wolfram's automaton. All measurement occurs in terms of quantum information, but time, space, energy, and quantum informations are merely approximations generated by Wolfram's automaton. Measurement is a natural process that separates the boundary of the multiverse from the interior of the multiverse. During each Planck time interval, gravitational energy is transferred from the boundary of the multiverse into the interior of the multiverse. There are a huge (but finite) number of alternate universes, all of which are on the boundary of the multiverse. The multiverse is mathematically isomorphic to a 72-dimensional holographic, digital computer in the form of a giant ball controlled by the monster group, the 6 pariah groups, and Wolfram's cosmological automaton. There are 6 basic quarks because there are 6 pariah groups. Einstein's field equations, after quantum averaging, require 3 modifications: a Koide cutoff, a Lestone cutoff, and dark-matter-compensation-constant = (3.9±.5) * 10^-5 . The 3 modifications are required to model Milgrom's MOND and the Riofrio-Sanejouand cosmological model (which allows the redefinition of the inflaton field). The string theorists think that Viewpoint B is nonsense -- are they correct?

      9 days later

      Does string theory with the finite nature hypothesis provide a new paradigm for understanding uncertainty?

      Louis Marmet founded "A Cosmology Group" (ACG) to publicize problems with the Lambda-CDM model.

      ACG Position (with empirical evidence聽against the Lambda-CDM model)

      Louis Marmet, York University

      In string theory with the infinite nature聽hypothesis, the string vibrations聽are not synchronized among alternate universes -- thus allowing 聽a chaos of incomprehensibility in terms of physical experiments. In string theory with Wolfram's cosmological automation, there are 2 highly testable predictions:

      (1) relativistic MOND (i.e. dark-matter-compensation-constant = (3.9卤.5) * 10^-5) and

      (2) the Riofrio cosmological model (which allows the replacement of Guth's inflaton field by a new inflaton field defined in terms of the Riofrio cosmological model).

      Can supersymmetry be empirically refuted? No, because all of the superpartners might have wavelengths that are too short or too long for detection. Is supersymmetry useful in theoretical physics? Yes, supersymmetry is needed for the Einstein-Riofrio duality principle. In string theory with the infinite nature hypothesis, we assume that, after quantum averaging, Einstein's field equations are 100% correct. In string theory with the finite nature hypothesis, we assume that, after quantum averaging, Einstein's field equations need 3 corrections. Put D-brane supercharges on gravitons, gravitinos, inflatons, and inflatinos. This allows an embedding of a model of string theory with the finite nature hypothesis into a model of string theory with the infinite nature hypothesis.

        Is uncertainty infinite or finite? Is nature infinite or finite?

        According to Tegmark, " ... infinity is an extremely convenient approximation for which we haven't discovered convenient alternatives."

        "Infinity Is a Beautiful Concept -- And It's Ruining Physics" by Mag Tegmark, Discover Magazine, 2015

        I have suggested 3 modifications to Einstein's field equations:

        "Einstein's field equations: 3 criticisms", 2017

        One modification attempts to refute the hypothesis that energy-density continuously approaches zero. Another modification attempts to refute the hypothesis that energy-density can be infinitely large. The modification dark-matter-compensation-constant = (3.9±.5) * 10^-5 attempts to provide a model for relativistic MOND. The hypothesis that nature is finite seems to be in conflict with the hypothesis that, after quantum averaging, Einstein's field equations are 100% correct.

        Marmet is a very nice man...

        He spoke at one of the first Physics conferences I attended CCC-2 (2nd Crisis in Cosmology Conf.) and Louis was inspirational. Many of the objections raised in his stated position linked above still stand. Possibly of interest would be the diagram from his proceedings paper which is reproduced on its cover, detailing the redshift predictions for various (10 different) models 'Angular distance a s a function of redshift.' I think I still have an electronic copy of that volume on one of my working computers, and I can forward his paper with that diagram if you like.

        All the Best,

        Jonathan