The External Field Effect In MOND

Stacy McGaugh explains at his blog, Triton Station, how important it is to consider the external field effect (in which external gravitational fields prevent MOND effects from arising) when using astronomy data to determine if MOND is a good description of reality. Because, when the external field effect is strong enough, MOND reduces to Newtonian gravity.

Quick Human Evolution Hits

* John Hawks makes a pretty convincing case, from several studies using different methodologies but reaching similar conclusions, that about 1.1 to 1.5 million years ago, hominins split into two populations, the smaller of which (about 20% of the total) was the progenitor population of modern humans, Neanderthals, and Denisovans, and the larger of which (about 80% of the total) contributed about 20% to modern human genetic ancestry right around the time, about 300,000 years ago, that modern humans are first found in the archaeological record. The rub: fitting that into a narrative drawn from non-genetic evidence is challenging, because we don't know what ghost population the population that we broke off from and then partially hybridized with represents. He cites to many academic journal articles for his blog post whose citations are in a bibliography at the end of the linked article.

* Footprints from a group of about eight Paranthropus boisei about 1.4 million years ago seem to imply a larger scale of social organization for this early hominin than was previously assumed. The linked story cites to: Kevin G. Hatala, et al., "Insights into hominin body size, locomotion, and behavior from Early Pleistocene trackways in northern Kenya." 123(31) Proceedings of the National Academy of Sciences (2026). DOI: 10.1073/pnas.2530996123

* Descriptions of the last chimpanzee-hominin ancestor may be wrong because we have underestimated the things that primates can do with their feet. The linked story cites to: Luke D. Fannin, Carmen Pape, W. Scott McGraw. "A kinematic convergence in ape and monkey vertical climbing informs debates on early hominin arborealism." 123(35) Proceedings of the National Academy of Sciences (2026) DOI: 10.1073/pnas.260818312

Simple Math Made Hard

It is worth noting that none of the complexities below involve anything more sophisticated that pre-calculus study and logs and trig functions, and perhaps the early part of a first course in calculus, both of which are often taught at the high school level. 

Indirect Experimental Constraints On The X17 Hypothesis

A new analysis constrains the properties of a hypothetical X17 particle using experimental measurements of muon g-2 and electron g-2. It does not rule out the X17 particle hypothesis, although it does meaningfully constrain the properties it can have if it does exist.

We combine the current experimental muon g−2 world average, which incorporates the final Fermilab result, with the latest electron g−2 determinations based on cesium and rubidium measurements to set 95% CL exclusion contours for a pure vector mediator coupled to leptons. We explicitly test the assumption that the electron and muon coupling magnitudes are equal by comparing this restricted case with the case of independent electron and muon couplings and quantify the impact on the allowed parameter space. 

In the minimal visible dark-photon model, both leptons constrain the same kinetic mixing and are analyzed through a combined χ2 analysis. We compare the resulting g−2 bounds with existing accelerator direct-search exclusions and model-dependent astrophysical and cosmological constraints. From the accelerator comparison, we identify a region in the (mA′,|ϵ|) parameter space near 17~MeV, close to the reported X17 mass, that remains allowed by the direct-search contours displayed here but is excluded by the cesium-based electron g−2 constraint. The rubidium-based fit does not exclude this interval. 

For an X17 boson with independent lepton couplings, we constrain the electron and muon couplings separately. Electron-only direct searches leave two disconnected allowed regions near the reported X17 mass: a newly reopened low-coupling interval and a higher-coupling region above the NA64 excluded band. The cesium-based electron g−2 constraint closes the higher-coupling region, while the rubidium-based constraint reduces its extent; neither affects the newly reopened low-coupling interval. 

Using the current experimental muon g−2 world average, we obtain a new g−2-based exclusion region for the muon coupling, with no significant preference for a nonzero coupling.

Raoul Serao, Antonio Capolupo, "Electron and Muon g−2 Constraints on Light Vector Bosons: Dark Photons and the X17 Boson" arXiv:2608.24677 (August 25, 2026).

Proof By Counterexample

Artificial intelligence programs have recent disproved some famous mathematical conjectures by finding counter-examples.

Most mathematical proofs are deductive. They reason, point by point, from axiom, to lemma, to theorem, in a straight forward, X implies Y, Y implies Z, fashion.

Some mathematical proofs, arguably more elegant ones, are inductive. A common structure of an inductive proof is roughly speaking: imagine that this theorem is not true. Then, X could imply Y, and if X implies Y, then Z must have a certain value, but Z can have a different value. Therefore, the theorem must be true.

Another form of inductive proof shows that if proposition X is true that proposition X+1 is true by deduction. Then, it shows that proposition X is true in a separate proof for a particular early case of X (and possibly by other separate proofs for several other early cases of X that come before the one you use to validate the rest of the cases). Thus, for the early case or cases, and all subsequent cases, the conjecture must be true.

Many theorems are also almost always true, but have some "trivial" exceptions, typically for things like values of variables that are equal to zero or one, or for the first few iterations of a series, with the theorem holding only after those iterations.

One of the most elegant and efficient ways to prove that a theorem is not true is with a counterexample. The theorem may be true for every situation or set of values considered, sometimes millions of them, but it takes only one counterexample to show that the theorem is not always true, and hence, is false.

For example, in the case of Fermat's Last Theorem, before it was prove to be true, one could have imagined a counterexample disproving it with just three whole numbers that defied it's rule, that could be stated in a line or two, even thought it has been numerically tested for millions of numbers and in the end, it it would take a proof hundreds of pages long to rigorously establish that it was true deductively.

Disproof of longstanding mathematical conjectures by counterexample is rare, but it has happened, even in the pre-computer era, for theorems that held in vast numbers of examples, with no flaws identified for many decades by extremely smart people trying hard to do so.

I haven't very exactly described this kind of conjecture, although I'm sure that a clever mathematician could do so, but let's assume for sake of argument that this kind of conjecture is susceptible to precise definition, and call this kind of conjecture a "near miss conjecture". 

Disproof of a near miss conjecture by counterexample, however, in and of itself, while it is efficient, indeed elegant, is also dissatisfying in the case of conjectures the hold true for so many examples and which defied logical reasoning to show that they are true or false for long periods of active efforts to do so. Disproof of a near miss conjecture by counterexample is dissatisfying because, while they do show that the conjecture is not true, they don't tell why the conjecture doesn't always work, even though it does work for so many cases and logically feels like it should work in every case.

Maybe the near miss conjecture is true for all but a finite set of counterexamples that is well defined, and can be used to modify the conjecture in much the same way as many theorems are modified to exclude a handful of trivial exceptions.

Maybe the near miss conjecture could be true if some other assumption so obvious that even smart people don't recognize that it needs to be made, add it. 

For example, a conjecture about the probability of heads or tails in a coin toss may need to be supplemented with the assumption that the coin doesn't land on its side and thus doesn't generate either a heads or a tails result, rescuing the near miss conjecture, which remains very useful, despite not being perfectly true without the added assumption.

Knowing why a disproof by counterexample is possible adds insight that the counterexample itself often does not.

Razib Khan On Our Current Understanding Of Human Evolution

Razib Khan's latest piece on human evolution in his Unsupervised Learning series takes a step back and looks at how the big picture has changed with new discoveries made in the last several decades.

His main point is that archaic hominin introgression may have originally been a much higher percentage of ancestry, with most archaic hominin introgression expelled in the roughly 1,000 years after the initial introgression due to natural selection and incompatibilities between archaic hominin sourced genes and modern human genes. I suspect that the 10%-20% percentage that he cites is quite a bit too high, but surely this did happen to some extent.

As usual, he educated synthesis of the research and evidence is pretty solid, even if not every assertion he makes in laying out a single coherent narrative (like the Population A and Population B that hybridize to form modern humans, with Neanderthals, Denisovans, and "ghost African" populations all derived from Population A hypothesis in the diagram below) has reached the level of academic consensus yet, and even if there is some room to quibble over fine details.

Some highlights of his piece (but please, click on the link and read the whole thing) are quoted below:

A generation ago, we imagined that Homo sapiens, “thinking man,” emerged fully formed in Africa over 100,000 years ago and swept away all our monstrous kin before us through dint of our sheer genius. Today, it seems more likely that it was we who were the monsters out of the dark, the demons about which Neanderthal mothers would tell their little-ones.

In 2002’s The Dawn of Human Culture, Stanford paleoanthropologist Richard Klein presented what at that time was the standard model of the recent origins of humanity. Some time before 50,000 years ago, a new form of human arose through some sort of mutational jump. Klein posited that our genius, our superiority, was because of a macromutation that enabled us to generate fully articulate language. Before the emergence of this new species of human, there were many varieties of human, or, more precisely, hominin. Neanderthals in Europe and Central Asia, various “archaic” lineages in eastern Eurasia, and also descendants of other Homo forms in Africa. 

Ω humans, whom many popular slogans would refer to as “Africans,” rapidly swept away all these varieties of humanity after 50,000 years.

And so it was for a decade. There were dissents; in 2006 Jeffrey Wall and Michael Hammer published Archaic admixture in the human genome. This paper reflected suspicion among many evolutionary geneticists that the orthodoxy promulgated was too pat and simplistic (see also Magnus Nordborg’s 1998 On the Probability of Neanderthal Ancestry). But‌ despite an underground counter-consensus, very few evolutionary geneticists were vocal on this issue in public. . . . This all changed in 2010, when Svante Paabo and colleagues reported that Neanderthal whole genomes yielded strong evidence of several percent admixture into non-Africans, as well as the discovery of a new human lineage in eastern Eurasia, the Denisovans, who also contributed about 5% of the ancestry of Papuans.

Previous work had almost entirely been a matter of inference derived from contemporary populations. You looked at genetic variation in people alive today and worked backward to plausible models of how that variation could have arisen. In the 1980s, geneticists examined mitochondrial lineages, which represent the direct matrilineal genealogy. Geneticists noticed that all non-African populations nested within African genetic variation. They soon replicated this result with the Y chromosome, passed only through males, and the autosomes (markers on chromosomes 1 through 22) representing the whole genetic heritage. These results neatly dovetailed with the findings of paleoanthropologists like Chris Stringer of the British Museum of Natural History, who argued that modern human morphology, mostly exemplified by traits in human skulls, reflected continuity with African Homo, and not Neanderthals. Following the molecular genetic results, researchers applied similar phylogenetic methods to morphometric traits and discovered the same pattern of non-Africans nesting within African variation.

It was an immaculate and tidy story. . . . And that still seems to be much of the story. But not the entire story.

Over the last few years, geneticists have concluded that a much higher fraction of non-African DNA was originally Neanderthal. In an interview with Dwarkesh Patel Harvard’s David Reich asserted that as much as 10-20% of the overall heritage of early non-Africans, just as they were expanding out of the Near East 50,000 years ago, may have been Neanderthal. 

How then is that today we detect only about 2% Neanderthal genes outside of Africa? 

The genome rapidly sheds genetically incompatible segments within a few thousand years via purifying selection. Because Neanderthals diverged from our predominantly African ancestors 600 to 700,000 years ago, their overall genetic makeup exhibited much more striking incompatibilities with the expanding Africans than occurs when different branches of our own species mix (the deepest division in our own lineage dates to about 200,000 years, when Khoisan ancestors diverged from everyone else). No doubt the same phenomenon applied to Denisovan admixture, which today in some Oceanian populations, like those in New Guinea or the indigenous populations of the Philippines, approaches 5% or so.

What does this all mean? 

Because natural selection changes allele frequencies in ways that are out of step with the overall genome, the signatures that we get from modern and ancient DNA are deceptive as to the demographic dynamics of early anatomically modern humans and the Neanderthals (and Denisovans) whom they encountered. All the evidence, both ancient and modern, points to a tiny non-African ancestry population between 50 and 60,000 years ago, a few thousand individuals at most (some models posit a bottleneck of 200 breeding individuals!). If 10-20% of the ancestry of the early modern human expansion, also known as the Initial Upper Paleolithic (IUP), was Neanderthal, that implies the integration of hundreds of Neanderthals, as opposed to ten or twenty.

Did Archaic Ghost Hominins Admix With Humans In Africa?

This article supports the highly plausible theory that all humans share pre-Out of Africa admixture with "ghost" archaic hominin populations, but the methodology used is fairly new and untested.

Admixture between modern humans and extinct hominins has shaped the genomes of present-day individuals, but reconstructing this history has been constrained by the scarcity of archaic samples and unadmixed outgroup populations. 

We introduce TRACE, a reference- and outgroup-free approach that uses features of ancestral recombination graphs to identify archaic ancestry. Simulations show TRACE has high precision and low false discovery rates. 

Applied to 1000 Genomes, TRACE recovers known Neanderthal and Denisovan introgression and uncovers ghost admixture from uncharacterized hominins in both Africans and non-Africans. Ghost ancestry persists in Neanderthal and Denisovan ancestry deserts, challenging their interpretation as Homo sapiens–specific regions. In Oceanians, TRACE finds deep lineages are enriched in Denisovan compared to Neanderthal regions, supporting super-archaic introgression. TRACE enables mapping archaic introgression without archaic genomes.

Yulin Zhang, Arjun Biddanda, Sarah A. Johnson, Colm O’Dushlaine, and Priya Moorjani, "Recovering signatures of archaic hominin introgression using ancestral recombination graphs" Science (July 30, 2026) (open access) DOI: 10.1126/science.aef887

Replicating MOND In A Spin-Foam Model

Spin-foam is a quantum gravity approach that quantizes space-time, rather than treating gravity as a separate force with a carrier boson comparable to a photon or a gluon.

We argue that effects of the quantum spin-connection foam, which describes quantum gravity according to the precanonical quantization of General Relativity, may already be observed in the form of the small cosmological constant and a modification of Newtonian dynamics at small accelerations, manifested in the flat rotation curves of galaxies. 

We obtain a modification of the Newtonian potential that takes into account the existence of a fundamental small acceleration scale, a∗ = 8πGℏϰ, where ϰ is a parameter with the dimensions of inverse spatial volume that appears on dimensional grounds. The connection between ϰ and the hadronic scale of the mass gap in the pure Yang-Mills sector of the Standard Model leads to an estimated value of a∗ compatible with the Milgromian acceleration scale in MOND. The connection between a*^2 and the cosmological constant leads to a realistic value of the latter. Milgromian MOND, together with a theoretically distinct interpolating function, is derived under the assumption that classical dynamics is modified by the mean-field acceleration calculated from the simplest solution of precanonical quantum gravity in the nonrelativistic approximation. 

We also indicate that the effects of Newtonian dynamics modified by the spin-connection foam may be observable in the Solar System and even in laboratory experiments.

Igor V. Kanatchikov, Valery A. Kholodnyi, "Effects of Quantum Spin-Connection Foam in the Solar System, Galaxies, and the Universe" arXiv:2608.12404 (August 11, 2026) (The Seventeenth Marcel Grossmann Meeting on Recent Developments in Theoretical and Experimental General Relativity, Astrophysics, and Relativistic Field Theories, Pescara 7-12 July 2024, edited by G. Vereshchagin and R. Ruffini, this https URL, October 2026).

Hadronic B Decay Anomalies

The anomaly of the day is an anomaly in a certain kind of B meson decay. I'm very skeptical and think it will go away and is probably due to poor modeling of the Standard Model prediction, but I'll note its existence in this post for further analysis.

The decays B→PP, where the pseudoscalar P is a π or K, have been studied under the assumption of flavour SU(3) symmetry [SU(3)F]. The global fit shows a 3.6σ discrepancy with the Standard Model (SM). 

Separate fits for ΔS=0 and ΔS=1 decays find parameter sets that differ by a factor of 10, suggesting 1000% SU(3)F breaking, significantly larger than the ∼ 30% breaking expected in the SM. This study has been extended to include final states with η and η′ mesons. The resulting global fit, once again under the assumption of SU(3)F symmetry, is worse, with a 4.1σ deviation from the SM. When theoretical constraints |C˜/T˜| = 0.2 or A˜ = 0 are imposed, the fits worsen, with the discrepancy approaching 5σ. These results hint at new-physics contributions to these decays.

Marianne Bouchard, David London, "Anomalies in Hadronic B Decays" arXiv:2608.11298 (August 11, 2026) (Contribution to the Proceedings of the XVI International Conference on Beauty, Charm, Hyperons in Hadronic Interactions (BEACH 2026), 7-12 June 2026, Firenze, Italy).

Another Alternative To Particle Dark Matter

A Covarying Coupling Constant theory performs similarly to, but not better than MOND. Both are much better at explaining galaxy rotation dynamics than a Cold Dark Matter theory using an NFW dark matter distribution (which is theoretically necessary for truly sterile dark matter particles).

The Covarying Coupling Constants (CCC) framework, developed to account for high-redshift JWST observations, contains a mechanism -- a covarying-constant effective mass field keyed to local density -- that modifies galactic dynamics without particle dark matter. 

We test it against the full Spitzer Photometry and Accurate Rotation Curves (SPARC) sample of 175 disc galaxies, extending an earlier study of a few objects. Working in an inverse formulation, in which each model predicts the baryonic rotation curve from the observed one, we compare CCC against Modified Newtonian Dynamics (MOND) and one- and two-parameter Navarro-Frenk-White (NFW) haloes on identical footing, using the reduced χ2ν. We show that the published sharp density turn-off in the earlier study is unphysical and replace it with a smooth transition -- the density-space analogue of the MOND interpolating function, introducing no new parameter. One-parameter smooth-CCC then performs comparably to galaxy-by-galaxy fitted MOND (the lower χ(ν)^2 in 56 per cent of galaxies, mean χ(ν)^2 of 2.58 versus 2.65; the paired difference is not significant), while two-parameter NFW shows a substantially broader fit-quality distribution and a larger tail of poor or boundary-limited fits (mean χ(ν)^2≈7). The CCC turn-off density is not universal (scatter 0.82 dex) and correlates with galaxy size, qualitatively consistent with a spherical reconstruction applied to flattened disc systems. Recast as an acceleration, however, a(t) = V(flat)^2/R(t) has scatter 0.33 dex (on the 91-galaxy resolved subset) -- matching the MOND scale a0 (0.34 dex) -- and comparable magnitude of order 2×10^−10 m/s^2, with its size correlation removed. Though not designed for galactic dynamics, CCC describes rotation curves as well as galaxy-by-galaxy fitted MOND.

Rajendra P. Gupta, Nikolaos Samaras "Testing Covarying Coupling Constants (CCC) against the full SPARC rotation-curve sample: a like-for-like comparison with MOND and NFW" arXiv:2608.11575 (August 12, 2026).

Denisovan Remains May Be Younger Than First Believed

Not long ago, we were finally able to find decent sized bones that proteins provided proteomic evidence (rather than DNA evidence which was not available) were able to match to Denisovans, which were found on the coast of the main island of Taiwan, finally putting a body together with the ghost population implied by DNA evidence. Two more leg bones were recently found.

Earlier dating had suggested an age for the Taiwanese Denisovan remains of about 160,000 years ago, long before modern humans arrived in the region and overlapping with Homo erectus. Analysis of the new leg bones by a more reliable and credible method, however, reveals that they are actually just 45,000 years old, contemporaneous with a modern human presence in the region.

At one level this isn't a surprise. Modern humans in Southeast and East Asia and Oceania have genetic admixture from Denisovans, so they had to overlap at some point. But it is surprising that the two different dating methods differed from each other by a factor of four.

The chemical analysis also suggests that these Denisovans, like Neanderthals, had a diet heavy in meat from large mammals.

My link is to a blog post by John Hawks who cites his sources:

* Chang, Chun-Hsiang, et al., "The first archaic Homo from Taiwan." 6 Nature Communications 6037 (2015). doi:10.1038/ncomms7037

* Grün, R. & Stringer, C., "Direct dating of human fossils and the ever-changing story of human evolution." 322 Quaternary Science Reviews 108379 (2023). https://doi.org/10.1016/j.quascirev.2023.108379

* Kaifu, Y., Chang, et al., "Denisovan leg bones from Taiwan reveal large body size." bioRxiv (2026). https://doi.org/10.64898/2026.08.07.743438

* Tsutaya, et al., "A male Denisovan mandible from Pleistocene Taiwan." 388(6743) Science 176–180 (2025). https://doi.org/10.1126/science.ads3888

* Yoneda, et al., "Habitat and feeding ecology of a Denisovan from Late Pleistocene Taiwan." bioRxiv (2026). https://doi.org/10.64898/2026.08.07.743455

* Zhang, D., et al., "Denisovan DNA in Late Pleistocene sediments from Baishiya Karst Cave on the Tibetan Plateau." 370(6516) Science 584–587 (2020). https://doi.org/10.1126/science.abb6320

Systemic Deviations From The Radial Acceleration Relation?

There is weak evidence that the radial acceleration relation, which is implied by Milgrom's toy-model MOND theory of weak field gravity, requires a single parameter correction is correlated with the compactness of the galaxies measured, primarily in dwarf galaxies.

Query if this could be due to the external field effect or due to gravitationally bound systems that are not in equilibrium? It could also be due to underestimated systemic error in estimating gas fractions, which is much harder to determine that stellar mass.

We ask whether any one-parameter structural correction to the radial acceleration relation (RAR) can be uniquely recovered from SPARC rotation curves, and answer with an identifiability audit: each candidate is benchmarked against per-galaxy nuisance freedom, with predictive scoring against mass-only and data-quality baselines. 

In the full sample (N = 126) the answer is no: a hybrid compactness term improves the fit, but zero-point freedom absorbs the gain, and in cross-validation the model fails to out-predict a mass-only baseline and loses to a quality-flag baseline. 

One regime retains structural information: in gas-dominated, low-acceleration disks -- where MOND's strict locality and ΛCDM feedback models diverge most sharply -- the RAR residual correlates with compactness (r = 0.46, p = 1.3×10^−4), remains significant under hierarchical partial pooling (β = 0.23, p = 1.7×10^−5; N = 63), and survives canonical joint control for quality, sampling, mass, inclination error, and first-order pressure support (r = 0.30, p = 0.02). All significant results pass a Benjamini-Hochberg correction over the declared 27-test family. 

Three limits temper that survival: it is not significant under rank-based control over the widest proxy set; it resides in faint dwarfs independent surveys do not reach; and after mass control it is shared across the mass-size manifold. Pressure support brackets the interpretation -- isotropic drift correction absorbs a quarter of the amplitude, while a Jeans treatment overcorrects resolved cases -- leaving the physical origin undetermined. The audit's product is the extraction limit: claimed corrections must clear the 0.106 dex per-galaxy nuisance floor, a mass-only baseline, and data-quality stratification.

Lukas A. Sosna, "An Identifiability Audit of One-Parameter Structural Corrections to the Radial Acceleration Relation in SPARC" arXiv:2608.08945 (August 9, 2026).

Is Milgrom's Constant Really Constant?

Reductionist physicists always like to derive physical constants, rather than than simply measure them. This paper proposes a way to do so for modified gravity in a MOND-like theory, expanding the theory's domain of applicability to galaxy clusters while sacrificing the universality of Milgrom's constant, a(0). 

It also hints, as Deur explicitly concludes, that MOND-like effects may be influenced by the extent to which a matter distribution is (or is not) spherically symmetric, and provides a mechanism to explain why MOND-like effects arise.

Modified Newtonian Dynamics (MOND) generally resolves the need for dark matter in galaxy rotation curves introducing a single new constant of acceleration a(0). It is well known that increasing a(0) by a factor of a few can alleviate the residual mass discrepancies that MOND leaves in galaxy clusters. 

Within a parameter-free Machian interpretation of MOND, in which a(0) ∼ GM(u)/R(u)^2 arises from the scalar sum of inverse-square distance gravitational mass contributions in the universe, we promote a(0) to a variable influenced by mass external to a locally enclosed region in the spherically symmetric case. 

Instead of a boost of a(0) in terms of gravitational potentials as in EMOND, we show that a boost in terms of this directionless inverse-square field roughly amounts to the boost needed to accommodate the mass discrepancies of MOND in galaxy clusters. We conclude by beginning to generalize the proposed formulation beyond spherical symmetry.

Manuel Uruena Palomo, Juan David Santander, "Machian MOND: a variable a0 in galaxy clusters" arXiv:2608.04894 (August 5, 2026) (published version in International Journal of Modern Physics D).

Cloud-9

A hydrogen gas cloud, called Cloud-9, that has been observed in deep space in the radio wave frequency, which cannot be seen in the visible light spectrum provides a way to distinguish between different dark matter hypotheses and while the paper below doesn't consider it, between modified gravity theories and dark matter hypotheses.

Starless gas clouds provide a new way to test gravitational dynamics and this is just the first examination of many to come.

Between cold dark matter and self-interacting dark matter, the observations strongly favor self-interacting dark matter, although neither hypothesis is a great fit.

Recently, the Five-hundred-meter Aperture Spherical Telescope discovered a gas-rich hydrogen cloud near M94 in the 21cm band. Lacking an optical counterpart, this object, dubbed Cloud-9, has been identified as a compelling Reionization Limited H Cloud (RELHIC). RELHICs provide exceptionally clean laboratories for probing dark matter, free from the baryonic complexities associated with star formation and feedback. 

We show that the observed hydrogen column density profile of Cloud-9 is consistent with a gas cloud embedded in either a cuspy halo predicted by the standard cold dark matter (CDM) model or a cored halo produced by self-interacting dark matter (SIDM). 

In both cases, the halo must have an unusually diffuse central density. The best-fitting CDM halo lies around 7σ below the cosmological concentration--mass relation, whereas SIDM core-forming halos reduce the tension to only around 3σ. 

We further identify Cloud-9 analogs in the Concerto suite of cosmological zoom-in simulations with velocity-dependent SIDM, demonstrating that RELHICs provide a promising new probe of dark matter self-interactions.

Morgan Ohana, Xingyu Zhang, Hai-Bo Yu, "Cold Dark Matter and Self-Interacting Dark Matter Interpretations of Cloud-9" arXiv:2608.04362 (August 5, 2026).

Meanwhile, another new paper finds that the tight relationship between the distribution of baryonic matter and galactic rotation curves has held true for as far back as at least z=0.42 (i.e. 4.4 billion years ago) with astronomy data.

The Baryonic Tully-Fisher relation (BTFR) is one of the tightest scaling relations for disk galaxies in the local Universe, and therefore is an important tool for studying the fomation and evolution of galaxies. . . . 

A random forest classifier is used to investigate the origin of the outlier component. We find that low signal significance and inaccurate inclinations are the key factors that contribute to the outlier population, indicating that observational effects are the dominant origin. 

Evolutionary trends are examined in three different redshift bins. Both the slope and zero point show consistency within 1-σ uncertainty in the two low redshift bins, indicating no significant evolution.

A Possible Glueball Resonance

A glueball is a strong force bound system without any valence quarks that binds gluons, the carrier bosons of the strong force instead of quarks. A well-established resonance seen in experiments at discovery level significance since 2011, whose internal structure is unclear, is shown in a new preprint to be consistent with a nearly pure pseudoscalar glueball state (i.e. a spin-0, electromagnetically neutral boson with odd parity and no valence quarks).

The properties of glueballs (which depend primarily on a single experimentally measured physical constant, the strong force coupling constant), have been calculated from the very early days of quantum chromodynamics (QCD), which is the Standard Model theory of the strong force. And, there are only a modest number of theoretically possible glueballs. This resonance is on the low end of, but consistent with, the mass predicted for a pseudoscalar glueball.

But distinguishing a glueball resonance from a non-glueball resonance is difficult, and because glueballs are always bosons and share quantum numbers with bosons that include valence quarks, they have a natural tendency to blend with similar bosons making a mere glueball component in a resonance rather than a pure glueball, something that is probably common in reality.

There have only been a few resonances that have been convincingly interpreted as a near pure glueball, and this is one of them. But the fact that this is an analysis of a lone author which has not yet been published in a peer reviewed journal bodes caution in accepting this conclusion as definitive. But to the extent that this analysis holds up, it confirms an important qualitative prediction of QCD (i.e. the existence of glueballs with various quantum numbers that have their predicted masses).

In this work, we take the X(2370) with J^PC = 0−+ as a glueball consists of three valence gluons, and construct a six-quark current based on rigorous current-field duality to obtain the glueball-quark Lagrangian. Then we perform Fierz transformation to bosonize the quark current into a series of three pseudoscalar mesons. At last, we obtain ratios among the partial decay widths of the glueball to three pseudoscalar mesons in a model-independent way, which are compatible with the experimental data from the BESIII Collaboration and support assigning the X(2370) as a glueball.

Zhi-Gang Wang, "Analysis of the X(2370) as a glueball based on rigorous current-field duality" arXiv:2608.03362 (August 4, 2026).

In other physics news, the Higgs boson continues to be consistent with Standard Model expectations in newly observed ways.

Sterile Neutrino Parameter Space Further Constrained

Observations of high energy out space sourced neutrinos from an Earth based neutrino detector further constrain the parameter space of possible sterile neutrinos in a way that the LHC, reactor experiments, and an Antarctica based cosmic ray observatory do not.

While the sterile neutrino mass range probed (1-100 TeV) is vastly greater than the active neutrino mass range, this is a sterile neutrino mass range frequently considered in see saw neutrino mass models, so it is relevant for discriminating between hypotheses.

The money chart, below, is a bit difficult to explain, but the key point is that it adds new constraints that rule out sterile neutrinos with certain properties with masses ca. 12-120 TeV, that other experiments can't probe. 

We investigate the sensitivity of the Pierre Auger Observatory to physics beyond the Standard Model arising from magnetic-moment-induced transitions between active and heavy sterile neutrinos. Such dipole portal interactions can enhance neutrino-nucleon cross sections above a kinematic threshold set by the sterile neutrino mass, leading to observable modifications of neutrino detection rates at ultrahigh energies (UHE). 

We estimate the impact of these interactions on both down-going and Earth-skimming neutrino detection channels, the contrasting responses of which enable discrimination between an enhanced neutrino flux and a modified interaction cross section. Using the non-observation of UHE neutrino candidates, we derive neutrino-flux-dependent constraints with 90% confidence-level on the transition magnetic moment for sterile neutrino masses in the range 1 TeV-100 TeV. Under the assumed flux scenarios, the resulting flavor-independent limits extend existing bounds into previously unexplored parameter space.

Pierre Auger Collaboration, "Search for active-sterile neutrino transitions using Pierre Auger Observatory data" arXiv:2608.01496 (August 2, 2026).

A New Higgs Boson Mass Measurement

Every new precision measurement of the Higgs boson mass is golden, and it is increasingly being pinned down to some precision.

A measurement of the Higgs boson mass in the diphoton decay channel is performed using proton-proton collision data at a center-of-mass energy of 13 TeV. The data set recorded with the CMS detector between 2016 and 2018 is used, corresponding to an integrated luminosity of 138 fb−1. A refined detector calibration and new analysis techniques are employed to improve the precision of the results compared to earlier measurements. The Higgs boson mass is measured to be mH = 125.13 ± 0.15 GeV = 125.13 ± 0.10 (stat) ± 0.12 (syst) GeV. 

In addition, a combination with the mass measurement at center-of-mass energies of 7 and 8 TeV in the diphoton final state is performed resulting in mH = 125.06 ± 0.14 GeV = 125.06 ± 0.09 (stat) ± 0.11 (syst) GeV.

CMS Collaboration, "A measurement of the Higgs boson mass in the diphoton decay channel in proton-proton collisions at s√ = 13TeV" arXiv:2607.28396 (July 30, 2026) (Submitted to Physics Letters B.).

This result compares to a Particle Data Group global average of 125.13 ± 0.11 GeV (S = 1.5).

LambdaCMD Still Broken

No matter how much you fuss with the LambdaCDM based simulations, they generically predict the wrong number and type of satellite galaxies (related study here) producing a 2.4 sigma tension:

The kinematic approach yields a larger diversity in central dark matter densities than expected from the CDM population, as inferred from the stellar-to-halo mass relation, with compact ultra-faints appearing overdense and larger systems appearing underdense. For the ultra-faint dwarfs with at least 10 stars with spectroscopic measurements, this discrepancy persists at the ~2.4σ level across all considered systematic variations on the semi-analytic modeling.

The Hubble tension remains unresolved, which implies that the cosmological constant, Lamba, of the LambdaCDM model, isn't actually constant. And at galaxy scales, CDM has lots of problems:

Small-scale cosmic structure provides a powerful test of the fundamental nature of dark matter (DM). A wide range of DM models impact matter clustering on small scales, including warm, fuzzy, and (self-)interacting DM. In these scenarios, DM physics such as free-streaming, wave interference, and self/Standard Model interactions alter the abundance and internal structure of DM halos. Cosmological and astrophysical probes of nonlinear structure---including dwarf galaxies, strong lensing, the Lyman-α forest, stellar streams, and high-redshift galaxies---are therefore sensitive to these effects. 

Here, we review DM constraints provided by small-scale structure, focusing on observables that probe scales smaller than ∼1 Mpc, which define the frontier of current measurements. We summarize how these constraints have been translated to limits on microphysical DM models, and we discuss key modeling uncertainties and observational systematics. Finally, we highlight the growing importance of probe combination and simulation-based inference for this field, and we overview upcoming observational facilities that will sharpen small-scale structure tests of DM physics.

Ethan O. Nadler, Keir K. Rogers, Alex Drlica-Wagner, "Dark Matter Constraints from Small-Scale Cosmic Structure" arXiv:2607.28564 (July 30, 2026) (73 pages, submitted to Reviews of Modern Physics). The conclusion of this article states:

Over the past two decades, measurements of small scale structure have evolved from potential challenges to the CDM paradigm into a powerful probe of the fundamental nature of DM. For example, the combination of increasingly complete observations of faint galaxies and stellar streams, advances in strong lensing, and the development of flexible, empirically-grounded modeling frameworks has enabled robust inference that connects DM microphysics to data at the small-scale frontier. As a result, these probes now provide among the most stringent constraints on many DM properties, complementing LSS analyses and terrestrial experiments. At the same time, our understanding of small-scale cosmology remains incomplete, and new tensions have emerged on highly nonlinear scales, many of which are related to the inner densities of low-mass subhalos. 

Small-scale structure will likely play a central role in an eventual DM discovery. In the presence of a terrestrial detection, cosmological confirmation will be essential to show that newly-detected particles are the cosmological DM, and small-scale structure provides a uniquely sensitive avenue to achieve this goal. Conversely, evidence for departures from collisionless CDM inferred from nonlinear structure would offer critical guidance for direct detection and collider experiments by narrowing the viable particle DM parameter space. Thus, small-scale structure acts as a bridge between astrophysics and particle physics, creating interdisciplinary opportunities at the interface of astrophysical data and particle theory. 

A key milestone in the coming years will be the detection (or robust exclusion) of DM halos with masses below the galaxy formation threshold. Establishing the existence of completely dark halos would open a new observational window into structure formation and enable the most incisive small-scale structure tests of DM physics to date. On the other hand, an absence of such systems would constitute strong evidence against CDM and for DM physics beyond gravity. Either outcome will mark an important transition in our understanding of DM. 

Realizing the potential of upcoming small-scale structure data will require both observational and theoretical advances. On the observational side, next-generation facilities will dramatically increase the statistical power of current probes while enabling the first DM constraints from new data. On the theoretical side, progress will depend on accurately modeling nonlinear structure across DM scenarios, robustly marginalizing over the impact of baryonic physics on small-scale structure, and combining data from multiple probes in a unified framework. Together, these developments point toward a future in which small-scale structure enables precision tests—and perhaps discovery—of fundamental DM physics.

This article, however, is far too tentative and unwilling to drawn any conclusions from an already abundant supply of observations in its exceptionally long review of the literature and prospects for future study.

While the Hubble tension has received more widespread mainstream attention, the galaxy and galaxy cluster scale issues with cold dark matter particles is, IMHO, the far greater challenge to the LambdaCDM model. In measure after measure, it fails irremediably. 

The Linguistic Golden Age

The most notable findings of the study are that the number of languages in the world was already starting to decline five hundred years before the Columbian exchange and the Renaissance, and that small pre-agricultural populations placed an effective limit on the number of languages spoken in the pre-Holocene era. The peak number of languages was on the order of 10,000 to 35,000 according to the study under various model assumptions.

A linguistic “golden age” flourished between 1,000 to 3,000 years ago when tens of thousands of languages were spoken throughout the world, according to a new study coauthored by Yale linguist Claire Bowern that traces trajectories in global language diversity over the past 12,000 years.

The golden age was followed by a period of rapid decline in linguistic diversity that coincided with the rise of large states and multinational empires, such as the Roman Empire, the researchers found. The finding challenges a commonly held view that widespread language extinction began later, about 500 years ago, with the onset of European colonial expansion.

The languages of expanding states and empires were disproportionately likely to survive while those of absorbed, displaced, or declining populations disappeared, the researchers concluded. This means that the roughly 7,600 languages spoken or signed today represent a small and historically biased sample of the languages that once existed, which has important implications for the study of global patterns in language and culture, they said. . . .

The study, which was published July 23 in the journal Science, is the result of a long international collaboration between experts in language, demography, and evolutionary biology. . . .

Direct evidence of languages doesn’t exist before the appearance of writing about 6,000 years ago. So for the study, the researchers combined ethnographic information, estimates of prehistoric population size, and statistical and social-computational modelling to estimate linguistic diversity over the course of the Holocene — the current geological epoch that began about 12,000 years ago.

To gauge the likely distribution and sizes of populations before the advent of agriculture, the researchers used ethnographic data from 171 hunter-gatherer and fisher societies whose traditional subsistence and mobility had not been profoundly transformed by contact with food-producing populations. They combined these estimates with independent analyses suggesting that the global human population 12,000 years ago was between approximately 4.4 and 7 million. Assuming that the number of languages in the early Holocene corresponded with the number of distinct groups that the total human population could accommodate at the time, between 4,500 and 6,200 languages were spoken 12,000 years ago, the study’s models estimated.

The world immediately before agriculture was probably not exceptionally rich in languages,” said lead author Damián Blasi, an ICREA (Catalan Institution for Research and Advanced Studies) research professor based at the Center for Brain & Cognition at the Pompeu Fabra University in Barcelona, Spain. “There were most likely fewer languages than there are today. Linguistic diversity then grew alongside the human population for thousands of years.”

To capture fluctuations in linguistic diversity as populations expanded dramatically following the onset of agriculture and technological innovation and then contracted through wars, plagues, and other ecological factors, the researchers modelled thousands of possible trajectories connecting language estimates at the beginning of the Holocene with the present.

The models consistently produced patterns indicating that language diversity peaked between 1,000 and 3,000 years ago when upwards of tens of thousands of languages were being spoken worldwide, this period that the researchers call the world’s linguistic “golden age.”

That golden age ended with the rise of states and multinational empires as the dominant groups spread their languages, cultures, and pathogens to previously independent populations, the study shows. European colonialism intensified the steep decline in linguistic diversity, but did not cause it, according to the study.

The loss of so much linguistic diversity over the course of two millennia affected the development of today’s languages, the researchers said.

“The languages we see today are the survivors of a massive and highly selective historical bottleneck,” said study coauthor Russell Gray, director of the Department of Linguistic and Cultural Evolution at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. “A linguistic feature may be common not because it is inherently efficient or better for communication, but because it happened to be carried by populations that expanded. Extinction may have shaped linguistic diversity much more profoundly than we previously appreciated.”

"Study uncovers lost ‘golden age’ of languages: A new study coauthored by Yale linguist Claire Bowern suggests that tens of thousands of languages were spoken between 1,000 and 3,000 years ago." via a Yale University press release.

Conventional linguistic reconstruction methods struggle to reconstruction linguistic pre-history much before 4,000 to 8,000 years ago.

The 7,600 languages spoken today is rapidly falling (according to Ethnologue, there are approximately 7,159 known languages spoken around the world today). A very large share of all languages spoken today have a small number of speakers or are moribund and on the brink of extinction in the next couple of generations or sooner. 

The general consensus is that between 6,000 and 7,000 languages are currently spoken. Some linguists estimate that between 50% and 90% of them will be severely endangered or dead by the year 2100. The 20 most common languages, each with more than 50 million speakers, are spoken by 50% of the world's population, but most languages are spoken by fewer than 10,000 people. . . . More than 50% of the world's endangered languages are located in just eight countries: India, Brazil, Mexico, Australia, Indonesia, Nigeria, Papua New Guinea and Cameroon.

From Wikipedia. About 107 languages are spoken by 7 million people or more and about 200 languages are spoken by a million people or more. A list of the number of languages per country can be found here. 

Roughly 40% of languages have less than 1,000 speakers (that's a total of 3,193 endangered languages) spoken collectively by much less than 3 million people out of 8.3 billion people in the world. About 10 million people speak a language that is spoken by 10,000 or fewer people. About 46 languages have only a single speaker. The Ainu language of Japan has 10 speakers. The median Australian Aboriginal language has 10 speakers. The median Native American language in the U.S. has 12 speakers. The median Brazilian indigenous language has 210 speakers. The median Papuan language has 1,315 speakers. The median Indonesian language has 3,500 speakers. The median Mexican indigenous language has 4,730 speakers. The median languages spoken in Cameroon has 10,000 speakers. The median language in Nigeria has 14,000 speakers. The median language in India has 35,000 speakers. 

Reviving an extinct or endangered or purely liturgical language is not impossible but is very difficult and there have been only about twenty moderately successful attempts to do so. The most successful effort has been the Hebrew language.

The Model Dependence Of Cosmological Neutrino Mass Estimates

Even with greatly relaxed cosmology based bounds in neutrino mass that free it from the strong model dependence it has in the deeply flawed ΛCDM model, cosmology based limits on neutrino mass have a 90% confidence level upper bound that is about five times more strict than direct measurements of neutrino mass.

The relaxed less model dependent bound on neutrino mass still limits the lightest neutrino mass to about 60 meV in an inverted hierarchy scenario, and to about 73 meV in a normal neutrino mass hierarchy. In the restrictive and model dependent ΛCDM model estimation of the neutrino masses, there is a normal neutrino mass hierarchy and the lightest neutrino mass can't be much more than 2 meV which a best fit value that is much smaller than that.

Very low neutrino masses greatly limits the role that neutrinos can play to make up the gap between modified gravity theories that account for most, but not all, dark matter phenomena, such as MOND.

Neutrino oscillations establish that neutrinos are massive, providing the only laboratory detection of physics beyond the Standard Model. Direct kinematic experiments bound the electron-neutrino mass to m(νe) < 0.45 eV (KATRIN, 90% CL), implying ∑m(ν) ≲ 1.3 eV. 

Conversely, cosmology within ΛCDM is highly constraining: Planck CMB, CMB lensing, and DESI DR2 BAO yield ∑m(ν) < 0.056 eV (95% CL), in 2-3σ tension with the inverted-ordering floor (0.10 eV). However, this bound relies on ΛCDM, while data hint at an evolving dark energy. 

To determine the model dependence of cosmic neutrino mass bounds, we deconstruct each probe's sensitivity to late-time physics and pursue two robust routes to a ∑m(ν) bound: 

(i) The existing dark-energy-marginalized route, retaining all data and marginalizing over (w(0),w(a)), is shown to also be immune to flexible binned and cubic w(a) histories, yielding ∑m(ν) < 0.152 eV, sharpening to σ(∑m(ν)) ≈ 0.043 eV with Simons Observatory lensing and Spec-S5 BAO.

(ii) A new late-Universe-free route combines primary CMB, marginalizing over acoustic-peak smoothing via Alens, with the reconstructed lensing spectrum CκκL, removing late-time expansion dependence by construction. This yields ∑m(ν) < 0.41 eV today, tightening to 0.31 eV (Simons Observatory) and 0.28 eV (cosmic-variance limit) across all tested dark-energy models. These relaxed bounds trade statistical power for model independence. Interestingly, they land in the sensitivity range targeted by next-generation laboratory experiments like Project 8 (m(νe) ∼ 0.1 eV), motivating vital synergies between future cosmological and terrestrial neutrino measurements.

Frank J. Qu, et al., "Measuring Cosmic Neutrino Masses Independently of Dark Energy" arXiv:2607.24742 (July 27, 2026).