The dominant paradigm for dark matter has long been the weakly interacting massive particle (WIMP). WIMPs are hypothetical particles motivated by supersymmetry. This is well-posed scientific hypothesis insofar as it makes a testable prediction: the cold dark matter thought to dominate the cosmic mass budget should be composed of a particle with a mass in the neighborhood of 100 GeV that interacts via the weak nuclear force – hence the name.

That WIMPs couple to the weak nuclear force as well as to gravity is what gives us a window to detect them in the laboratory. They should scatter off of nuclei of comparable mass, albeit only on the rare occasions dictated by the weak force. If we build big enough detectors, we should see it happen. This is what a whole host of massive, underground experiments have been looking for. So far, these experiments have succeeded in failing to detect WIMPs: if WIMPs existed with the properties we predicted them to have, they would have been detected by now.

The failure to find WIMPs has led to the consideration of a myriad of other possibilities. Few of these are as well motivated as the original WIMP. Some have nifty properties that might help with the phenomenology of galaxies. Most are woefully uninformed by such astrophysical considerations, as it is hard enough to do the particle physics without violating some basic constraint.

One possibility that most of us have been reluctant to contemplate is a particle that doesn’t interact at all via strong, weak, or electromagnetic forces. We already know that dark matter cannot interact via electromagnetism, as it wouldn’t be dark. It is similarly difficult to hide a particle that responds to the strong force (though people have of course tried, with strange nuggets in the ’80s and their modern reincarnation, the macro). But why should a particle have to interact at least through the weak force, as WIMPs do? No reason. So what if there is a particle that has zero interaction with standard model particles? It has mass and therefore gravity, but otherwise interacts with the rest of the universe not at all. Let’s call this the Angel Particle, because it will never reveal itself, no matter how much we pray for divine intervention.

I first heard this idea mooted in a talk by Tom Shutt in the early teens. He is a leader in the search for WIMPs, and has been since the outset. So to suggest that the dark matter is something that simply cannot be detected in the laboratory was anathema. A logical possibility to be noted, but only in passing with a shudder of existential dread: the legions of experimentalists looking for dark matter are wasting their time if there is no conceivable signal to detect.

Flash forward a decade, and what was anathema then seems reasonable now that WIMPs remain AWOL. I hear some theorists saying “why not?” with a straight face. “Why shouldn’t there be a particle that doesn’t interact with anything else?”

One the one hand, it’s true. As long as we’re making up particles outside the boundaries of known physics, I know of nothing that precludes us from inventing one that has zero interactions. On the other hand, how would we ever know? We would just give up on laboratory searches, and accept on faith that “gravitational detection” from astronomical evidence is adequate – and indeed, the only possible evidence for invisible mass.

Experimentalists go home! Your services are not required.

To me, this is not physics. There is no way to falsify this hypothesis, or even test it. I was already concerned that WIMPs are not strictly falsifiable. They can be confirmed if found in the laboratory, but if they are not found, we can always tweak the prediction – all the way to this limit of zero interaction, a situation I’ve previously described as the express elevator to hell.

If there is no way to test a hypothesis to destruction, it is metaphysics, not physics. Entertaining the existence of a particle with zero interaction cross-section is a logical possibility, but it is also a form of magical thinking. It provides a way to avoid confronting the many problems with the current paradigm. Indeed, it provides an excuse to never have to deal with them. This way lies madness, and the end of scientific rationalism. We might just as well imagine that angels are responsible for moving objects about.

Indeed, the only virtue of this hypothesis that springs to mind is to address the age-old question: how many angels can dance on the head of a pin? We know from astronomical data that the local density of angel particles must be about 1/4 GeV cm-3. Let’s say the typical pin head is a cylinder with a diameter of 2.5 mm and a thickness of 1 mm, giving it a volume of 10 mm3. Doing a few unit conversions, this means a dark mass of 1 MeV* per pin head, so exactly one angel can occupy the head of a pin if the mass of the Angel particle is 1 MeV.

Of course, we have no idea what the mass of the Angel particle is, so we’ve really only established a limit: 1 MeV is the upper limit for the mass of an angel that can fit on the head of a pin. If it weighs more than 1 MeV, the answer is zero: an angel is too fat to fit on the head of a pin. If angels weighs less than 1 MeV, then they can fit numbers in inverse proportion to their mass. If it is as small as 1 eV, then a million angels can party on the vast dance floor that is the head of a pin.

So I guess we still haven’t answered the age old question, and it looks like we never will.

*An electron is about half an MeV, so it is tempting to imagine dark matter composed of positronium. This does not work for many reasons, not least of which is that a mass of 1 MeV is a coincidence of the volume of the head of a pin that I made up for ease of calculation without bothering to measure the size of an actual pin – not to mention that the size of pins has nothing whatever to do with the dark matter problem. Another reason is that, being composed of an electron and its antiparticle the positron, positronium is unstable and self-annihilates into gamma rays in less than a nanosecond – rather less than the Hubble time that we require for dark matter to still be around at this juncture. Consequently, this hypothesis is immediately off by a factor of 1028, which is the sort of thing that tends to happen when you try to construct dark matter from known particles – hence the need to make up entirely new stuff.

God forbid we contemplate that maybe the force law might be broken. How crazy would that be?

Stacy McGaugh is an astrophysicist and cosmologist who studies galaxies, dark matter, and theories of modified gravity. He is an expert on low surface brightness galaxies, a class of objects in which the stars are spread thin compared to bright galaxies like our own Milky Way. He demonstrated that these dim galaxies appear to be dark matter dominated, providing unique tests of theories of galaxy formation and modified gravity. Professor McGaugh is currently the chair of the Department of Astronomy at Case Western Reserve University in Cleveland, Ohio, and director of the Warner and Swasey Observatory. Previously he was a member of the faculty at the University of Maryland, having also held research fellowships at Rutgers, the Department of Terrestrial Magnetism of the Carnegie Institution of Washington, and the Institute of Astronomy at the University of Cambridge after earning his Ph.D. from the University of Michigan.

59 thoughts on “The Angel Particle”

  1. People still pushing for the “reality” of dark matter in spite of direct evidence for it are just following the herd/groupthink and mostly trying to keep milking the cow of almost unlimited social gullibility.

    At this point they are essentially not different than flat earthers, that they are the majority or mainstream is irrelevant as the history of science clearly shows that the majority/mainstream is almost always wrong and progress in science is almost synonym with showing that that majority or experts of the moment are dead wrong.

    Liked by 1 person

  2. 11292022 I would settle for 1/137 as an explanation,,,good enough for me at this time
    Example :: teaching humans how to think ,,,whatever is to be found ,has been found, COAL IS KING
    teaching humans a lesson !!!
    (On facbook ,just leave public note)

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  3. I wonder if long-term observation of a conveniently-located black hole could test for the “Angel Particle”, by comparing the amount of normal matter going in to the change in mass effects of the black hole.

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  4. “But why should a particle have to interact at least through the weak force, as WIMPs do? No reason.”

    (A minor comment for other readers — I’m sure Stacy is very familiar with this):

    I believe the motivation for the weak force comes from the idea of “freeze out”: IF there were a heavy stable particle that has the weak force and you use known physics to predict how much of it would be around today it turns out its abundance would be similar to the observed dark matter abundance (that you infer in the CDM model). Yes, people have come up with zillions of modifications and loopholes, but the original, simple “WIMP miracle” story is a fair and suggestive hint for weak force dark matter in my opinion.

    I do completely agree with the post’s main point though. Experiment must be the final word. If no one detects the particle then wimp freeze out is only an interesting physics story. And no one should be satisfied closing down the field with an explanation that dark matter is a new particle with only gravity (unless people can think up some other testable implications besides non-detection in WIMP searches).

    Anyway very clear and reasonable as always!

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    1. Sure, we can include these in the grab bag of potential goodies. But they don’t do anything to explain the phenomenology of galaxies, so just seems like more mud to fling at the wall in hopes that some of it sticks.

      Liked by 1 person

  6. “A logical possibility to be noted, but only in passing with a shudder of existential dread: the legions of experimentalists looking for dark matter are wasting their time if there is no conceivable signal to detect.”
    The moment each one comes to the awful conclusion that it was all for naught. But it had to be done, they had to look, and there’s always risk of losing.
    The agony & the ecstasy.
    Hopefully MOND will get a boost of new interest & willingness to analyze your data,
    and collect new data.

    Liked by 1 person

  8. If a particle doesn’t interact via any force other than gravity, how does it get created in the first place, during the big bang or at any time? At least a hypothetical WIMP can be created using a weak interaction. Can a particle with mass be created purely from gravitational force?

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    1. I have no idea. You are correct that WIMPs are relics that had been in thermal equilibrium mediated by the weak force, and that natural origin story does not apply to the angel. So we would have to look for another formation mechanism, which can happen – it doesn’t have to be thermal. Here it is tempting to get religious: Let there be angels…

      Liked by 1 person

    2. There is observational and theoretical evidence that gravity is spacetime curvature (pure geometry) as emitted from supermassive black holes(10% SMB energy emitted as gravitational waves See LIGO SMB Merger report). I believe the author of this article is correct with stating WIMPs are located around the 100Gev area however, what a particle accelerator and detector in a lab cannot do perfectly as nature does with SMBs is accrete large masses allowing the particles to stabilize and work their gravitational spacetime curvature magic.

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  9. Dark matter only interacting via gravity is the nightmare scenario for theoretical particle astrophysicists in the same way that the non-detection of superpartners at the LHC was the nightmare for supersymmetry theorists, because it means that their preferred theory no longer has any meaningful ties to reality and all their time and effort has been wasted. And just like the sypersymmetry theorists. I’d expect the particle dark matter physicists to give up on the field in the next few years and move on to something else.

    Liked by 3 people

    1. Anyhow, less particle physicists theorising about dark matter particles would be healthier for the field in general, because it means that it allows alternatives to dark matter to have more space in the public consciousness, such as modified gravity approaches and gravity self-interaction approaches.

      Liked by 2 people

    2. I consider half of String Theory to be interesting mathematics, regardless of whether it is fundamental physics, would you agree?

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        1. Empirical evidence reigns supreme but for some theory takes precedence over it, obviously this is not objective but dogmatic.

          Naive Reductionism always leads to a departure from objectivity because once you have a set of basic principles that appear to describe the elementary components of a system then everything should be reduced/explained/predicted from these principles, so any new empirical evidence should fit, otherwise it is wrong or we need to postulate a “dark matter” because our assumptions are universal, they can’t be wrong.

          A departure from objectivity is the unavoidable end result of Naive Reductionism: assuming that a theory have universal range of applicability.

          Objectivity is the only guide and Reality is a source of unlimited irreducible facts, dogmatism is the alternative.

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        2. I also think it would have started better without oh so sure statements about new particles. There should have been a separation of concerns between determining the real elementary particles experimentally and formulating a general theoretic framework for elementary particles. If the theory has appeal, cool, but why then jump without evidence to “this should be how nature works”? Of course that’s what you want to know as theorist and these ideas give interesting leads, but the experimental data must always remain the final deciding factor.

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          1. We’ve been chasing atomism since Democritus. All that has been found are focal points that somehow seem to be on a spectrum with fields at the other end. Logically there is some dynamic in the middle, like a convection cycle, between these ends.

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        3. From your perspective, the situation may be frustrating. But from my point of view, the situation is excellent. The situation is excellent for becoming immortal or at least very famous. We know extremely much and understand very little.

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  10. Many years ago, I came across this interview with Carver Mead, who, among many other accomplishments, did the math behind Moore’s Law. Where he argues, after decades working and designing at the quantum level, there are no real “particles.” That it’s waves all the way down;

    http://worrydream.com/refs/Mead%20-%20American%20Spectator%20Interview.html

    “Once upon a time, Caltech’s Richard Feynman, Nobel Laureate leader of the last great generation of physicists, threw down the gauntlet to anyone rash enough to doubt the fundamental weirdness, the quark-boson-muon-strewn amusement park landscape of late 20th-century quantum physics. “Things on a very small scale behave like nothing you have direct experience about. They do not behave like waves. They do not behave like particles …or like anything you have ever seen. Get used to it.”

    Carver Mead never has.

    As Gordon and Betty Moore Professor of Engineering and Applied Science at Caltech, Mead was Feynman’s student, colleague and collaborator, as well as Silicon Valley’s physicist in residence and leading intellectual. He picks up Feynman’s challenge in a new book, Collective Electrodynamics (MIT Press), declaring that a physics that does not make sense, that defies human intuition, is obscurantist: It balks thought and intellectual progress. It blocks the light of the age.”

    What if it’s really the atomism paradigm that’s wrong? That it’s generations of preconceptions and artifacts of measurement devices? That there are no tiny things, just permutations of positive and negative charge?

    Then we might start thinking of matter as an effect of this centripetal dynamic, referred to as gravity, rather than gravity a property of mass.

    That would be the nightmare scenario. Which would extend far beyond theoretical physics. How do we explain materialism, not to mention reductionism, if there ultimately is no “matter?”

    Liked by 2 people

  12. if by 2023 X17 particle is verified what does this means that for dark matter vs. MOND ?

    X17 particle could rewrite dark matter theoretical issue

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    1. So by X17 I presume you mean that we actually discover some form of new, unexpected particle. What it means for this debate depends on what its properties are. How does it interact with other particles? What is its mass? How many of them are there? If there is a particle that checks all the necessary boxes, then that would solve the problem. That’s a tall order – there was a time I thought it was crazy to suppose that the neutrino had mass, but it was once a leading candidate for the dark matter. So, I figured, if it turns out to have mass, then surely that is the answer to the dark matter problem. Well, wrong and wrong – neutrinos do have mass, but it is no where near enough to help. So we’re at a point where one needs to do a LOT more than make up a new particle, but so far that’s all we’ve managed.

      Liked by 1 person

      1. the PADME experiment, the NA64 experiment at CERN SPS, ARIEL experiments Montreal Tandem accelerator are all in the search for X17, the particle physics interpretation of the anomaly observed by the ATOMKI nuclear physics experiment possible results for 2023. if successful i would like your opinions.

        could dark matter particles be some combination of axion, sterile neutrinos, and Planck relics

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        1. Ah – I hadn’t heard that name for it before. There are many small anomalies that get a lot of attention because there is so little new particle physics left to do. Most of these fail to launch – the anomalies go away after some months. That’s normal – not every hint of new physics pans out; most do not. If this does, then I’ll get interested. Until then, it is Schrodinger’s anomaly, both viable and not. I’ve learned to wait for the box to be opened before investing too much in any one claim. So I don’t know if X17 would make a viable dark matter candidate. Probably not – there can be other particles that have everything to do with the anomaly they cause and nothing to do with the dark matter problem. People like to leap to the conclusion that it might because the situation has become that desperate. Desperation is not a strong scientific argument.

          Liked by 1 person

  13. Just chuckling at the thought that here we are, speculating on what is matter…
    it’s not finite real things we call particles, but fields (according to Sean Carroll)….or strings,
    or spinfoams, extra-dimensions at the Planck level…yet it all works somehow to create us.

    I’d love to know the history of just one proton that’s currently a part of my body, since the Big Bang or whatever happened 13.8 billion years ago.
    If they could only talk.

    Liked by 1 person

    1. What I do see is energy expressing form.
      Energy drives the wave, the fluctuations rise and fall.
      Consequently the energy goes past to future, because the forms it expresses come and go, future to past. Tomorrow becomes yesterday, because the earth turns.
      So the energy radiates out, as the forms coalesce in, because the waves synchronize, as a path of least resistance. Basically synchronization versus harmonization. Between black holes and black body radiation. Mass is the information wrapped up in this somewhat stable, intermediate stage, that our tactile sensibilities prioritize.
      Consequently we have nodes and networks, organisms and ecosystems, particles and fields.

      Liked by 1 person

        1. Consciousness also goes past to future, while the perceptions, emotions and thoughts giving it form and structure go future to past. Though it’s the digestive system processing the energy, while the central nervous system sorts the information, so there is an intellectual tendency to focus on the patterns. Thus the obsession with math.
          The gut decides, the head advises.

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  14. ‘Something’ is altering the gravitational force law as implied by MOND at galactic and extra-galactic scales. That ‘something’ correlates tightly with the baryonic mass such that the MOND ‘foot’ fits nearly perfectly in a very wide range of galactic ‘shoe’ sizes and styles. But once a large number of shoes are assembled on a cluster ‘rack’ MOND’s correlation with baryonic mass is off by a factor of about 2. So there is a temptation to impute the existence of some unseen particles, even in MOND, to accommodate the galactic cluster scale. But any such particles have a tall order to fill. They must explain the dynamics of galaxies without the inherent problems associated with the Concordance model’s Dark Matter halos. In fact it would seem that DM halos need to be abandoned altogether as all attempts to shoehorn this paradigm into galactic behavior have proven quite ridiculous as the LCDM cobblers have demonstrated with attempts at achieving comfortable fits via mechanisms like feedback, etc. Yet the particle approach can’t be ruled out as attested by Alexander Deur’s quantum version of gravitational self-interaction invoking gravitons. But whether gravitational self-interaction is sufficiently robust to explain deviations from Newtonian behavior at large scales is still apparently controversial.

    Liked by 3 people

    1. Even MOND, as general relativity, has a limited range of applicability.

      Expecting that a single theory can be applied to multiple levels of complexity structures, like galaxies and then cluster of galaxies, is the trademark of naive reductionism.

      Just look at condensed matter Physics to see the similarities.

      Again as P. Anderson said: More is different.

      Complexity is a boundary for the predictive/explanatory power of any theory, ignoring this is naive reductionism and the root of many problems in theoretical physics.

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  15. @David Schroeder
    “…the MOND ‘foot’ fits nearly perfectly in a very wide range of galactic ‘shoe’ sizes and styles.” Great metaphor & assessment of the current situation. If the shoe fits… 😉

    Liked by 1 person

    1. @3dcal
      Thank you for the compliment. In that comment I was going to mention a personal theory paper, that I’ve been working on like forever, but then thought better of it, as it would sound like a broken record – always near completion, but never quite there, like in Zeno’s Paradox. The model tries to resolve the DM/DE mystery by invoking gravitons, as does Alexandre Deur’s theory but from an entirely different approach. However, while Deur’s work is wholly professional, my model is, for sure, amateur and very speculative. In fact, ironically, it has a pair of built-in ‘Angel particles’ that carry a unique type of charge. While these particles arise from a symmetry operation, it is not supersymmetry. But I won’t say any more as it’s not proper to discuss personal theories, especially amateur ones, on this and other blogs. When or if I finish the paper I’ll put it up on the viXra platform.

      Liked by 1 person

  16. Angel particle, a.k.a. sterile dark matter or purely collisionless DM, is pretty much ruled out too.

    This follows from evidence including that:

    (1) inferred DM halos don’t take a NFW halo shape. See, e.g., Mariia Khelashvili, Anton Rudakovskyi, Sabine Hossenfelder, “Dark matter profiles of SPARC galaxies: a challenge to fuzzy dark matter” arXiv:2207.14165 (July 28, 2022); Nicolas Loizeau, Glennys R. Farrar, “Galaxy rotation curves disfavor traditional and self-interacting dark matter halos, preferring a disk component or ad-hoc Einasto function” arXiv 2105:00119 (April 30, 2021); Pengfei Li, Federico Lelli, Stacy McGaugh, James Schombert, “A comprehensive catalog of dark matter halo models for SPARC galaxies” (January 28, 2020). arXiv 2001.10538 and https://arxiv.org/abs/1905.02739 and https://arxiv.org/abs/1701.02698 and James S. Bullock, Michael Boylan-Kolchin, “Small-Scale Challenges to the ΛCDM Paradigm” (July 13, 2017, last updated September 2, 2019) arXiv 1707.04256; Marie Korsaga, et al., “GHASP: an Hα kinematics survey of spiral galaxies – XII. Distribution of luminous and dark matter in spiral and irregular nearby galaxies using Rc-band photometry” (September 17, 2018); Theodorus Maria Nieuwenhuizen “Subjecting dark matter candidates to the cluster test” (October 3, 2017); Lin Wang, Da-Ming Chen, Ran Li “The total density profile of DM halos fitted from strong lensing” (July 31, 2017) and https://arxiv.org/pdf/1305.7452v2.pdf

    (2) baryon feedback effects can’t solve the problem. See https://arxiv.org/abs/1706.03324 ;

    (3) distributions of hydrogen in interstellar space are also inconsistent with it. See Zhixing Li, Hong Guo, Yi Mao, “Theoretical Models of the Atomic Hydrogen Content in Dark Matter Halos” arXiv:2207.10414 (July 21, 2022); and

    (4) the insufficiently strong correlation with baryonic matter in collisionless DM models. See, e.g., Aidan Zentner, Siddharth Dandavate, Oren Slone, Mariangela Lisanti, “A Critical Assessment of Solutions to the Galaxy Diversity Problem” arXiv:2202.00012 (January 31, 2022), and https://arxiv.org/abs/2202.00038; Lorenzo Posti, S. Michael Fall “Dynamical evidence for a morphology-dependent relation between the stellar and halo masses of galaxies” Accepted for publication in A&A. arXiv:2102.11282 [astro-ph.GA] (February 22, 2021); Paolo Salucci, “The distribution of dark matter in galaxies” (November 21, 2018) (60 pages, 28 Figures ~220 refs. Invited review for The Astronomy and Astrophysics Review); https://arxiv.org/abs/2008.04052 and Antonino Del Popolo et al., “Correlations between the Dark Matter and Baryonic Properties of CLASH Galaxy Clusters” (August 6, 2018) and https://arxiv.org/abs/2010.01186; Edo van Uitert, et al., “Halo ellipticity of GAMA galaxy groups from KiDS weak lensing” (October 13, 2016); Paolo Salucci and Nicola Turini, “Evidences for Collisional Dark Matter In Galaxies?” (July 4, 2017).

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    1. Yes, there are different levels of viability. If we simply want “a possible particle” that constitutes some unseen mass in the universe, then sure – there are lots of possibilities, and many of them can be made to pass the bar to be candidates for cold dark matter. To me, that is a very low bar. One really needs to explain the the rich phenomenology encapsulated by the simple MOND formula, for which there are exactly zero satisfactory candidates. There are a few merely unsatisfactory ones (dipolar dark matter, superfluid dark matter) that are still viable. However, by this higher standard, we can immediately exclude the vast bulk of DM candidates as having no possibility of becoming viable. In this I include WIMPs and any other idea that must rely on gastrophysical effects like feedback to somehow magically “look like” MOND. This should become a textbook example for philosophers and historians of science for how science can go off the rails.

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  17. Stacy,

    I like your blog.
    Of all the blogs I know, I like your blog more than any other.
    For the following reasons:
    – Everything is explained in a way that a 12 year old can understand. The first Einstein criterion for understanding.
    – You base your reasoning on an experiment or observation.
    – The blog has a clear goal and worthwhile objective.

    Particle physicists have as their first problem:
    There are no particles. We know this from the double slit experiment.
    There are no waves either. We also know that from the double-slit experiment.
    Wave-particle dualism is just the acceptance of a contradiction.
    Sometimes I read something like: An electron is a wave function.
    A wave function is a dead mathematical object used by humans.
    But an electron exists also without this mathematics.
    An electron exists also without any QFT physicists.

    But well, let’s give it all a chance:

    The WIMPs must then not only be particularly dark, but also miraculous.
    In areas with low baryonic mass they are frequent or gravitationally very effective,
    but in areas with a lot of baryonic matter they are rare or gravitationally less effective….
    Your blog post: https://tritonstation.com/2016/10/03/four-strikes/

    It is relaxing for me to read your blog.
    I can think about MOND in a relaxed way.
    And I get an idea how a particle realizes the Lorentz transformation, this
    sqrt(1-v^2/c^2)

    Stefan

    Liked by 2 people

    2. What if the “energy” and whatever information can be extracted from it are not the same?
      What if they are in fact diametrically opposed?
      Say energy expands toward infinity, as information coalesces toward equilibrium? Both entropic.
      That energy, manifesting the present, goes to the future, while any information collapses into the past. Potential versus residual. The present consumes the past. Cause becomes effect.

      I suppose the first issue would be whether the field could wrap its collective head around even considering it, given the overwhelming focus on the information. My experience is that it simply does not compute. Even the generally open minded cannot let go of their belief in the school of thought.

      (Given my 20 years of irritating bloggers on wordpress, I suspect I’m on the main troll list and while Stacy has allowed me access to this, my like button doesn’t work, so assume I am liking various posts.)

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  18. It seems we are locked into a reductio ad absurdum. The infinite is divided by nil. It had Einstein in a quandary. What does it mean? Holy cow. Am I the only one who knows the answer?

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  19. Here’s a thought. Reductio at observant can be put into notation. A note from Alien School. For those who are observant.

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  20. Even Open AI ChatGPT had been trained to believe in the “reality” of dark matter:

    Me: Dark Matter doesn’t exist.

    ChatGPT AI: I’m sorry, but that statement is incorrect. Dark matter is a hypothetical form of matter that is believed to make up about 27% of the universe. It is called “dark” because it does not interact with light in the same way that ordinary matter does, making it difficult to detect. While the existence of dark matter has not yet been proven conclusively, there is strong evidence to support its existence.

    You can interact with this AI here:
    https://chat.openai.com/chat?

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    1. I was wondering about that. It depends on the training set the AI gets, obviously. I’d say that it needs to read my papers, but it isn’t reading in the sense that you and I comprehend. It is scanning and assigning a score to common phrase occurrences, so it will slavishly repeat the most common mantra – just as you provoked it to do. I wonder if some more indirect prompt might get a different response, but I doubt it: there has already been a qualitative study where an expert posed statements in his field to it, only to have it authoritatively tell him he is wrong about the thing he is an authority on. It’s like a distillation of all the worst that social media has to offer.

      Liked by 1 person

      1. Actually I recommended it to read your articles here but it said that it doesn’t have access to the internet, obviously its training set is being limited to “mainstream” sources.

        Thanks for your reply, your articles are essential reading for science “dissidents”.

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      2. Actually, you can get ChatGPT to take essentially any position you want, if you are ingenious enough with the prompt.

        I didn’t try to make it a MOND advocate, but here are its opinions on the baryonic Tully-Fisher relation: https://pastebin.com/0PGxz1Wn

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        1. You can also make it “understand” that the rotational speed of galaxies is an emergent property of the system, making dark matter superfluous, by introducing it first the idea of emergence via classical mechanics as an emergent property of a large set of quantum particles and relating it to More is Different from P. Anderson.

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        2. Me:
          You don’t need to introduce any new particles to explain the rigidity of solids, exactly as you don’t need to introduce dark matter to explain the rotational speed of galaxies.

          ChatGPT:
          That’s correct. In both cases, the emergent properties that arise from the interactions between the individual components of the system are sufficient to explain the behavior of the system as a whole. In the case of solid rigidity, the interactions between the atoms or molecules that make up the solid are enough to explain the solid’s rigidity, without the need to introduce any new particles or other entities. Similarly, in the case of the rotational speed of galaxies, the interactions between the individual stars, gas, and other matter in the galaxy are enough to explain the galaxy’s behavior, without the need to invoke the existence of dark matter.

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        1. But it is getting better and better, a great help to generate basic code, debugging, generating summaries, even being better than humans in programing code competitions.

          It will reach a point when raw data can be feed into AIs to generate synthesizing hypothesis without any preexisting biases, many existing mainstream ideas will become obsolete immediately.

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  21. any comment

    Astrophysics > Astrophysics of Galaxies
    [Submitted on 26 Sep 2022]
    Dwarf galaxies with central cores in modified Newtonian dynamics (MOND) gravity
    J. Sanchez Almeida (1 and 2) ((1) Instituto de Astrofisica de Canarias, La Laguna, Spain, (2) Departamento de Astrofisica, Universidad de La Laguna, Spain)

    Some dwarf galaxies are within the Mondian regime at all radii, i.e., the gravitational acceleration provided by the observed baryons is always below the threshold of g†≃1.2×10−10ms−2. These dwarf galaxies often show cores, in the sense that assuming Newton’s gravity to explain their rotation curves, the total density profile ρ(r) presents a central plateau or {\em core} (dlogρ/dlogr→0 when r→0). Here we show that under MOND gravity, the existence of this core implies a baryon content whose density gbar must decrease toward the center of the gravitational potential (gbar→0 when r→0). Such drop of baryons toward the central region is neither observed nor appears in numerical simulations of galaxy formation following MOND gravity. We analyze the problem posed for MOND as well as possible workarounds.

    Comments: Accepted for publication in ApJ
    Subjects: Astrophysics of Galaxies (astro-ph.GA)
    Cite as: arXiv:2209.12547 [astro-ph.GA]

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  22. Satcy, here is a simple way to put your argument: particles have, by definition, inertial mass. To measure inertial mass, the particles must alow to be pushed or stopped. This HAS to happen by some non-gravitational interaction. A particle that has no such interaction does not have a way to measure its inertial mass. It is not a particle in the usual sense.

    A thing that has no short-range interactions is a thing that cannot be pushed. It thus is not a particle.

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