A Generalized MOND Paradigm For Weak Gravitational Fields And Experimental Confirmation Of GR In Strong Gravitational Fields

This new (published) paper is a provocative generalization of the MOND paradigm, although still not a true "FundaMOND" in the sense of providing a rigorous, fundamental physical explanation for why the phenomenological MOND paradigm is observed in Nature. 

Notably, MOND addresses gravity in the extremely weak gravitational field regime.

The primary author, Robin Eappen, who is a doctoral student in astrophysics, is not well know. But Pavel Kroupa is one of the leading MOND proponents (and is perhaps a little less mainstream in his scientific positions and his manner of advocating for them, than either Mordehai Milgrom who devised MOND in 1983, his now deceased colleague in astrophysics, Jacob Bekenstein, or Stacey McGaugh, one of MOND's leading proponents in the current generation of astrophysicists).

Mass discrepancies in galaxies are empirically known to appear only below a characteristic acceleration scale a(0). 

Here we show that this behaviour is not limited to galaxies: it extends continuously across the full hierarchy of self-gravitating stellar systems, from gas-rich dwarfs and spirals to massive early-type galaxies, and further down to compact stellar clusters. 

We introduce the Milgromian dynamics (MOND) depth index DM, together with dynamical maturity index T = t(cross)/t(H), dynamical collisionality index T(1) = t(cross)/t(relax), with t(cross) being the crossing time, t(H) the Hubble time and t(relax) the median two-body relaxation time, and the MOND acceleration index A = a(bar)/a(0). 

We uncover a well-defined two-dimensional dividing surface in dynamical space. The "dark matter phenomenon" is found only in systems that are both in the deep-MOND regime (a(bar) < a(0)) and collisionless (t(relax) > t(H)), while high-acceleration, collisional systems (a(bar) > a(0), t(relax) << t(H)), including globular clusters and UCDs, show no evidence for a mass discrepancy. 

This clean dynamical separation defines a new, physically motivated classification scheme for stellar systems, unifying galaxies and clusters under one framework. The observed division emerges naturally within the MOND framework and provides a useful diagnostic for examining how different gravitational paradigms account for the origin of the mass discrepancy.

Robin Eappen, Pavel Kroupa, "The MOND Depth Index and Dynamical Maturity Clock: Toward a Universal Classification of Galaxies and Star Clusters" arXiv:2603.18135 (March 18, 2026) (published in 14(2) Galaxies 22 (2026)).

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In other gravity news, a series of three papers (one, two and three) look at gravitational wave observations of extremely strong gravitational fields created by black holes and/or neutron star binary systems to test General Relativity (GR) in this regime in various ways. 

All of this evidence is consistent with GR and more tightly constrains deviations from GR in this strong field context than prior tests of GR.

Nailing Neutrino-Nucleus Interaction Rates

An experimental test of how frequently neutrinos interact with atomic nuclei has a best fit value of the Standard Model expectation and an uncertainty of less than ± 15%, which is impressive given how slight the interaction is, fit 10^22 trials yielding just 124 observed interactions.

The COHERENT collaboration reports the most precise measurement of the coherent elastic neutrino-nucleus scattering cross section to date. This measurement was performed with COHERENT's germanium detector array, Ge-Mini, at the Spallation Neutron Source at Oak Ridge National Laboratory. 

A cumulative exposure of 4.68 × 10^22 protons on target yielded a total number of observed counts of 124 + 14 −12 and a flux-averaged cross section of 1.00 ± 0.10 (statistical) ± 0.10 (systematic) relative to the standard-model expectation of 5.9 × 10^−39 cm^2. 

The well-understood energy and timing distributions of the neutrino source allow for independent measurements of muon- and electron-neutrino scattering rates. This information is used to improve constraints on non-standard neutrino interactions mediated by heavy particles.

M. Adhikari, et al., "Measurement of coherent elastic neutrino nucleus scattering on germanium by COHERENT" arXiv:2603.17951 (March 18, 2026).

Palau Is An Oceania Outlier

This is a further refinement of an already pretty well worked out story of Oceanian origins. 

The ultimate source of Oceanian and Austronesian seafaring people was one of the indigenous tribes of what is now called Taiwan (we have identified which of them it was based upon linguistic evidence), via island Southeast Asia.  

Before expanding very far east, however, these Formosan origin Lapita people admixed with Papuan people (in an encounter that amounted to a hostile conquest).

This "graphical abstract" really sums up a new paper on the topic. 

Note that the dates in this image are "before present", i.e. before 1950 by archeological convention, and not BCE. The initial settlement of Palau was roughly contemporaneous with the Greek "dark ages" after Bronze Age collapse, for example, while the admixture of the people who settled Palau was contemporaneous with the Late Bronze Age in Europe.

An educated layman's explanation of the paper explains: 

About 3200 years ago, Southeast Asian seafarers known as the Lapita pushed east into the tropical islands of the Pacific Ocean, hitting nearly every habitable isle in that corner of the globe from New Guinea to Fiji and Tonga. As they did so, they left behind artifacts of their culture, including pottery stamped with distinctive geometric patterns.

But on Palau, there’s not a single shard of Lapita pottery—and the island’s inhabitants speak a language that’s distinct from the tongues spoken on other Pacific islands. So who were the first Palauans, and where did they come from?

A new study published last week in Cell suggests an answer. Genetic evidence confirms Palau’s first settlers descended from Southeast Asians who had intermingled with the Papuans, Indigenous peoples who settled the island of New Guinea some 50,000 years ago.

“It’s lovely to see a piece of Pacific history—which we’ve traditionally been at a bit of a loss to explain—finally start to come together into a more understandable story,” says Murray Cox, a computational biologist at Massey University of New Zealand who wasn’t involved in the new work.

The discovery builds on previous ancient DNA research into the origins of the Lapita themselves. That work, led by evolutionary biologist David Reich at Harvard University and his colleagues, showed that Lapita were essentially pure Southeast Asians of Taiwanese roots—but that modern populations on Pacific islands showed Papuan ancestry, too. The studies suggested this Papuan ancestry came in about 2500 years ago, as Papuans began to join the same canoe voyages that had earlier carried Lapita settlers into the region.

From Science.

The underlying paper in Cell is as follows:

Highlights

• Ancient DNA of 21 individuals from Palau spans around 2,400 years

• Papuan-East Asian admixture in Palauans predates initial settlement

• Over 2,900 years of genetic continuity in Palau

• Shared East Asian-Papuan admixture in Palau and eastern Indonesia 

Summary 

The first people reached Remote Oceania 3,000 years before present (BP), arriving roughly simultaneously in the southwest Pacific, the Marianas Archipelago, and Palau. However, no genome-wide ancient DNA data have been available from Palau, a gap we address by reporting 21 individuals from four archaeological sites dating between 2,900 and 500 BP. 

All had approximately 60% ancestry related to East Asians and 40% to Papuans, similar to present-day Palauans, the longest stretch of population continuity anywhere in Remote Oceania. The lengths of contiguous Papuan ancestry segments in the oldest individuals show that major admixture between Papuans and East Asians in the ancestors of all sampled Palauans began prior to first settlement. This differs from the pattern in the southwest Pacific, where sampled individuals of the Lapita archaeological culture from three different islands had almost entirely East Asian ancestry, with large amounts of Papuan admixture observed only hundreds of years later. 

Yue-Chen Liu, et al., "Papuan admixture predated the settlement of Palau" (March 10, 2026).