Salient ET impacts, volcanic eruptions and climate events

Version one of this post is from memory. I plan to add links and confirm details later.

ET Impacts:

1. The Tunguska event. Russia, June 30, 1908.

2. The meteor strike that destroyed Sodom and Gomorra. Levant, 1650 BCE.

3. The Young Dryas impact. North America, ca. 12,900 years ago in North America.

4. The Southeast Asian ET impact.  Tens of thousand of years ago.

5. The ET impact that killed the dinosaurs. ca. 66 million years ago.

Volcanic eruptions:

1. Mount Tambora. Indonesia. 1815.

2. The eruptions that led to the Justinian plague. ca. 536 CE.

3.  Pompei. Mount Vesuvius. 76 CE. Italy.

4. The volcanic eruptions at the Upper Paleolithic boundary in Europe that probable drove modern human Cro-Magnon replacement of Neanderthals. Europe. ca. 40,000 years ago.

5. The Toba eruptions ca. 75,000 years ago in Indonesia.

6.  Yosemite's last big eruption ca. 630,000 years ago.

Climate events:

1.  The European Little Ice Age. ca. 1300-1850 CE.

2.  The drought in the American SE that ended ancient Puebloan culture. 

3.  The drought that took down the Mayans. A century or two before Y1K.

4.  The horrible year: 536 CE.

5.  The Bronze Age collapse event. ca. 1200 BCE.

6.  The aridity event that preceded Indo-European expansion and led to collapses in civilizations in Europe, the Middle East, West Asia, and India. ca. 4,000 years ago.

7.  The Green Sahara and its end. ca. 15,000 to 5,000 years ago.

8.  The Younger Dryas. ca. 12,900 years ago. Delayed the Neolthic revolution by about 3,000 years.

9.  The Last Glacial Maximum ca. 20,000 years ago.

Another Dark Matter Particle Model Fail And Other Gravity Papers

Another (fairly byzantine) self-interacting dark matter particle model fails to reproduce the empirically observed baryonic Tully-Fischer relation, which MOND and several other gravity based explanations for dark matter phenomena naturally produce. 

This is a generic problem with the lion's share of all dark matter particle models that do not have ultralight bosons with masses of the same order of magnitude as the mass-energy of hypothetical typical gravitons as their dark matter particles.

But, some geometrical gravity based explanations of dark matter and dark energy phenomena have their own deep problems.

More optimistically, a new, theoretically observable and well-defined quantity to determine if gravity is quantum or classical in nature in future observations has been devised.

A Parts Per Thousand Measurement Of The Electroweak Mixing Angle

The weak mixing angle or Weinberg angleis a parameter in the Weinberg–Salam theory (by Steven Weinberg and Abdus Salam) of the electroweak interaction, part of the Standard Model of particle physics, and is usually denoted as θ(W). It is the angle by which spontaneous symmetry breaking rotates the original W(0) and B(0) vector boson plane, producing as a result the Z(0) boson, and the photon. Its measured value is slightly below 30°, but also varies, very slightly increasing, depending on how high the relative momentum of the particles involved in the interaction is that the angle is used for.

- Wikipedia.

In the Standard Model of Particle Physics, the electroweak mixing angle is a function of the ratio of the W boson mass to the Z boson mass, and is also a function a simple formulas that have the electromagnetic coupling constant and the weak force coupling constant as inputs.

The electroweak mixing angle is of mostly theoretical interest as a key derived parameter in the electroweak force unification (i.e. it can be calculated from other Standard Model fundamental constants) that was a key breakthrough in the development of the Standard Model of Particle Physics. 

A part per thousand measurement honestly isn't all that precise for electroweak physics (some physical constants in electroweak physics are known to parts per million levels or better), but since it doesn't have many direct engineering applications, its measurement is mostly a consistency check on the electroweak portion of the Standard Model as a whole, that provides a fairly tight global constraint on the magnitude of beyond the Standard Model physics of many varieties that can be consistent with the experimental data (in much the same way as muon g-2 measurements do). 

But, unlike muon g-2, at least at the precisions at which we can measure it, the electroweak mixing angle only receives electromagnetic force and weak force contributions, and does not receive QCD strong force contributions.

The measurement of this physical constant described in the paper below is made at the momentum scale of the Z boson pole mass, about 91.19 GeV/c^2, which in an energy range known as the electroweak scale.

This energy scale is considerably greater than the mass-energies of first and second generation quarks, the electrons, muons, tau leptons, protons, neutrons, and the light mesons that bind protons and neutrons in atomic nuclei. But, it is considerably less the the maximum momentum scales that can be reached at the Large Hadron Collider (LHC), which is the highest energy particle collider. 

The energy scale at which this measurement is made is about three orders of magnitude higher in energy scale than the energy scale at which the anomalous magnetic moment of the muon (i.e. muon g-2) is measured, which is about 0.10566 GeV/c^2.

This contribution presents a overview of a recent CMS-based determination of the effective leptonic weak mixing angle, sin2θℓeff, derived from forward-backward asymmetry measurements in Drell-Yan events at 13 TeV. Although the CMS analysis achieved a major reduction in uncertainties, its overall precision is ultimately limited by residual parton distribution function (PDF) uncertainties. 

This proceeding highlights the role of complementary CMS observables, which probe distinct parton-density combinations and provide additional constraints beyond those obtained from the original asymmetry measurement alone. 

The improved analysis yields a substantially reduced total uncertainty, resulting in sin2θℓeff = 0.23156 ± 0.00024. This result is consistent with the Standard Model prediction and represents the highest precision achieved so far in an individual determination of this parameter.

Arie Bodek, Hyon-San Seo, Un-Ki Yang, "Summary of the Precision Measurements of the Electroweak Mixing Angle in the Region of the Z pole" arXiv:2601.20717 (January 28, 2026).

The value measured by the CMS experiment at the LHC is about 0.00005 lower than the Standard Model prediction (which is about 0.2 sigma and indicates that the uncertainty in the measurement is probably overstated with conservative assumptions about its accuracy).

This result, more clearly than past experimental results, favors the Standard Model of Particle Physics over the beyond the Standard Model "two Higgs doublet" model, which which there are four extra Higgs bosons, two charged Higgs bosons (positive and negative), one odd parity Higgs boson, and one heavy even parity Higgs boson. 

Earlier LHC measurements (in blue), Tevatron measurements (in green), and pre-Tevatron measurements from LEP and SLD (in black), were collectively inconclusively in their relative preferences for the Standard Model compared to a two Higgs doublet model. The CDF M(W) value below is an outlier that has never been taken very seriously, and probably the product of some sort of subtle analysis error.

Cosmology Evidence For A Normal Neutrino Hierarchy

Cosmology data increasingly favors, even under dynamical dark energy models, a normal neutrino mass hierarchy over an inverted neutrino mass hierarchy, although still not at the five sigma "discovery" level.

Constraints from direct measurements of the neutrino's absolute masses are much less constraining, although neutrino oscillation data also favors a normal neutrino mass hierarchy, in a completely independent measurement, to a similar degree.

We present cosmological parameters measurements from the full combination of DESI DR1 galaxy clustering data described with large-scale structure effective field theory. By incorporating additional datasets (photometric galaxies and CMB lensing cross-correlations) and extending the bispectrum likelihood to smaller scales using a consistent one-loop theory computation, we achieve substantial gains in constraining power relative to previous analyses. 

Combining with the latest DESI baryon acoustic oscillation data and using cosmic microwave background (CMB) priors on the power spectrum tilt and baryon density, we obtain tight constraints on the ΛCDM model, finding the Hubble constant H0=69.08±0.37 kms−1Mpc−1, the matter density fraction Ωm=0.2973±0.0050, and the mass fluctuation amplitude σ8=0.815±0.016 (or the lensing parameter S8≡σ8Ωm/0.3‾‾‾‾‾‾‾√=0.811±0.016), corresponding to 0.6%, 1.7%, and 2% precision respectively. Adding the Pantheon+ supernova sample (SNe), we find a preference of 2.6σ for the w0wa dynamical dark energy model from low-redshift data alone, which increases to 2.8σ when exchanging the SNe with Planck CMB data. 

Combining full-shape data with BAO, CMB, and SNe likelihoods, we improve the dark energy figure-of-merit by 18% and bound the sum of the neutrino masses to Mν<0.057 eV in ΛCDM and Mν<0.095 eV in the w0wa dynamical dark energy model (both at 95\% CL). 

This represents an improvement of 25% over the background expansion constraints and the strongest bound on neutrino masses in w0waCDM to date. Our results suggest that the preference for the normal ordering of neutrino mass states holds regardless of the cosmological background model, and is robust in light of tensions between cosmological datasets.

Mikhail M. Ivanov, et al., "Reanalyzing DESI DR1: 4. Percent-Level Cosmological Constraints from Combined Probes and Robust Evidence for the Normal Neutrino Mass Hierarchy" arXiv:2601.16165 (January 22, 2026).

CDM Fails Again

I'm not surprised, but again and again and again, the evidence against cold dark matter theories piles up. 

The properties of substructure in galaxy clusters, exquisitely probed by gravitational lensing, offer a stringent test of dark matter models. Combining strong and weak lensing data for massive clusters, we map their total mass--dominated by dark matter--over the dynamic range needed to confront small-scale predictions for collisionless cold dark matter (CDM). Using state-of-the-art lens models, we extract four key subhalo properties: the mass function, projected radial distribution, internal density profile, and tidal truncation radius. 

We find that the subhalo mass function and truncation radii are consistent with CDM expectations. In contrast, the inner density profiles and radial distribution of subhalos are strongly discrepant with CDM. The incidence of galaxy-galaxy strong lensing (GGSL) from subhalo cores exceeds CDM predictions by nearly an order of magnitude, requiring inner density slopes as steep as γ≳2.5 within r≲0.01R200 consistent with core-collapsed self-interacting dark matter (SIDM), while the same subhalos behave as collisionless in their outskirts. Additionally, the observed radial distribution of subhalos hosting bright cluster member galaxies, explicitly modeled in the lens reconstructions, remains incompatible with CDM. Together, these small-scale stress tests reveal an intriguing paradox and challenge the dark matter microphysics of purely collisionless CDM and motivate hybrid scenarios, such as a dual-component model with both CDM and SIDM, or entirely new classes of dark matter theories.

Priyamvada Natarajan, Barry T. Chiang, Isaque Dutra, "New CDM Crisis Revealed by Multi-Scale Cluster Lensing" arXiv:2601.07909 (January 12, 2026).

Lava Worlds

Until most of my posts, this isn't notable because it sheds light on any deeper laws of physics. It is just amazing that worlds like this exist.

Lava worlds are rocky planets with dayside skins made molten by stellar irradiation. Tidal heating on these shortest-period planets is more than skin deep. We show how orbital eccentricities of just a few percent (within current observed bounds and maintained secularly by exterior companions) can create deep magma oceans. ``Lava tidal waves'' slosh across these oceans; we compute the multi-modal response of the ocean to tidal forcing, subject to a coastline at the day-night terminator and a parameterized viscous drag. Wave interference produces a dayside heat map that is spatially irregular and highly time-variable; hotspots can wander both east and west of the substellar point, and thermal light curves can vary and spike aperiodically, from orbit to orbit and within an orbit. Heat deposited by tides is removed in steady state by a combination of fluid, mushy, and solid-state convection in the mantle. For Earth-sized planets with sub-day periods, the entire mantle may be tidally liquified.

Mohammad Farhat, Eugene Chiang, "Magma Ocean Waves and Thermal Variability on Lava Worlds" arXiv:2601.07080 (January 11, 2026) (Submitted to AAS Journals).

Baryonic Feedback

One of the ways to overcome the discrepancies between dark matter particle theories and what we observe is to attribute the discrepancies to baryonic feedback effects that are not terribly well understood. An ambitious new paper with many co-authors examines feedback effects in multiple cosmology simulations. The trouble is that the feedback seems to aggravate the discrepancies between what of observed and what simulations predict, rather than resolving them. 

Galaxy cores behave more or less like galaxies without dark matter phenomena, while the dynamics of galactic fringes are dominated by dark matter phenomena. And, more massive galaxies are less proportionately dark matter phenomena driven than less massive galaxies. Yet, these are just the opposite of the effects of baryonic feedback in the simulations considered.

Baryonic processes such as radiative cooling and feedback from massive stars and active galactic nuclei (AGN) directly redistribute baryons in the Universe but also indirectly redistribute dark matter due to changes in the gravitational potential. In this work, we investigate this "back-reaction" of baryons on dark matter using thousands of cosmological hydrodynamic simulations from the Cosmology and Astrophysics with MachinE Learning Simulations (CAMELS) project, including parameter variations in the SIMBA, IllustrisTNG, ASTRID, and Swift-EAGLE galaxy formation models. 

Matching haloes to corresponding N-body (dark matter-only) simulations, we find that virial masses decrease owing to the ejection of baryons by feedback. Relative to N-body simulations, halo profiles show an increased dark matter density in the center (due to radiative cooling) and a decrease in density farther out (due to feedback), with both effects being strongest in SIMBA (> 450% increase at r < 0.01 Rvir). The clustering of dark matter strongly responds to changes in baryonic physics, with dark matter power spectra in some simulations from each model showing as much as 20% suppression or increase in power at k ~ 10 h/Mpc relative to N-body simulations. 

We find that the dark matter back-reaction depends intrinsically on cosmology (Omega_m and sigma_8) at fixed baryonic physics, and varies strongly with the details of the feedback implementation. These results emphasize the need for marginalizing over uncertainties in baryonic physics to extract cosmological information from weak lensing surveys as well as their potential to constrain feedback models in galaxy evolution.

Matthew Gebhardt, et al., "Cosmological back-reaction of baryons on dark matter in the CAMELS simulations" arXiv:2601.06258 (January 9, 2026).

A new paper suggesting an interacting dark energy model is also intriguing.

Recent DESI baryon acoustic oscillation data reveal deviations from ΛCDM cosmology, conventionally attributed to dynamical dark energy (DE). We demonstrate that these deviations are equally, if not better, explained by interactions between dark matter and dark energy (IDE), without requiring a time-varying DE equation of state. Using a unified framework, we analyze two IDE models--coupled quintessence and coupled fluid--against the latest CMB (Planck, ACT, SPT), DESI BAO, and SN (including DES-Dovekie recalibrated) data. Both IDE scenarios show robust evidence for non-vanishing interactions at the 3-5σ level, with marginalized constraints significantly deviating from the ΛCDM limit. This preference persists even under DES-Dovekie SN recalibration, which weakens dynamical DE evidence. Crucially, for the same number of free parameters, IDE models provide fits to low- and high-redshift data that match or exceed the performance of the CPL dynamical DE parametrization. Our results establish IDE as a physically motivated alternative to dynamical DE, highlighting the necessity of future cosmological perturbation measurements (e.g., weak lensing, galaxy clustering) to distinguish between these paradigms.

Tian-Nuo Li, et al., "Strong Evidence for Dark Sector Interactions" arXiv:2601.07361 (January 11, 2026).

See also a new paper exploring Moffat's modified gravity approach, and a new paper examining the warm dark matter hypothesis.

Stacy McGaugh On Thin Galaxies

Astrophysicist Stacy McGaugh, at his Triton Station blog, observes that there are far more thin spiral galaxies than expected from cold dark matter halo explanations of galactic rotation curves. MOND does much better in this respect.

This is notable because MOND wasn't designed to produce this data point, and because once again, MOND is predictive while the LambdaCDM model of cosmology is not.

He is mostly highlighting results from a December 2025 paper by Benavides et al., that had escaped my notice in the daily flood of new astronomy papers. Some key illustrations from that paper:

q is a mathematical measurement of how thin a galaxy is relative to its diameter (roughly speaking, thickness divided by diameter). The chart above demonstrates how measurement effects driven by the angle of inclination at which we see galaxies make a world with many thin galaxies look more evenly spread.

This chart illustrates that LambdaCDM simulations dramatically underestimate the proportion of thin galaxies at all but the highest masses (and that many models don't even manage that match to reality at any point).

A final illustration is from one of McGaugh's own papers in 1998 and shows that MOND tends to produce flatter galaxies than Newtonian physics does (even though, unlike Deur's model, MOND is spherically symmetric, rather than relying, in part, on  the shape of a galaxy to demonstrate the dark matter replacing gravitational effect).

Neutrino Oscillations Disfavor Dark Dimensions And Right Handed Neutrinos

Two moderately popular beyond the Standard Model neutrino physics models are strongly disfavored by empirical data.

Right-handed neutrinos are naturally induced by dark extra dimension models and play an essential role in neutrino oscillations. The model parameters can be examined by the long-baseline neutrino oscillation experiments. In this work, we compute the predicted neutrino oscillation spectra within/without extra dimension models and compare them with the experimental data. We find that the neutrino data in the T2K and NOvA experiments are compatible with the standard neutrino oscillation hypothesis. The results set the stringent exclusion limit on the extra dimension model parameters at a high confidence level. The derived constraints on dark dimension right-handed neutrinos are complementary to those results from the collider experiments and cosmological observations.

Ai-Yu Bai, Auttakit Chatrabhuti, Yin-Yuan Huang, Hiroshi Isono, Jian Tang, "Dark Dimension Right-handed Neutrinos Confronted with Long-Baseline Oscillation Experiments" arXiv:2601.00790 (January 2, 2026).

An Alternative To MOND and Dark Matter

This deserves further attention. 

We present a new empirical model for galaxy rotation curves that introduces a velocity correction term omega, derived from observed stellar motion and anchored to Keplerian baselines. Unlike parametric halo models or modified gravity theories, this approach does not alter Newtonian dynamics or invoke dark matter distributions. Instead, it identifies a repeatable kinematic offset that aligns with observed rotation profiles across a wide range of galaxies. Using SPARC data [1], we demonstrate that this model consistently achieves high fidelity fits, often outperforming MOND and CDM halo models in RMSE and R-squared metrics without parametric tuning. The method is reproducible, minimally dependent on mass modeling, and offers a streamlined alternative for characterizing galactic dynamics. While the velocity correction omega lacks a definitive physical interpretation, its empirical success invites further exploration. We position this model as a local kinematic tool rather than a cosmological framework, and we welcome dialogue on its implications for galactic structure and gravitational theory. Appendix B presents RMSE and R2 comparisons showing that this method consistently outperforms MOND and CDM halo models across a representative galaxy sample.

David C. Flynn, Jim Cannaliato, "A New Empirical Fit to Galaxy Rotation Curves" arXiv:2601.00522 (January 2, 2026) (published at 12 Front. Astron. Space Sci. 1680387 (2025)).

Fairies And Fungi

* Fairy rings are a fungal phenomena.

* Fairies are often depicted as chthonic with underground halls, and eating fairy food traps you in their world forever. Fungi are one of the few living things that can survive and thrive underground without light.

* The Santa Claus myth and Christmas tree ornaments are deeply tied to hallucinogenic mushroom use by shamans in places where reindeer roam.

* Fungi are pervasively present in temperate forests which are seen as a natural habitat of fairies and were places feared in medieval times.

* Fairies are associated with glamours and deception, and many fungi, such as ergot, cause hallucinations and a sense of distortion of time..

* Fungal infections can make insects and small plants look and behave weirdly in ways that could cause them to be called fairies.

* The bane of fairies, iron and to a lesser degree salt, are inorganic while fungi are organic.

* Curious children eating mushrooms that cause their death or cause them to act abnormally could be associated with the changling myth.

* Fungi come in many varieties that are hard to distinguish from each other like fungi.

* Fungi have properties that distinguish them from "normal" biological things like plants and animals.

* Could "fairy dust" be spores or yeast?

* Mushrooms are of a scale often associated with fairies.

* There is a forests, fairies, and fungi sticker book anthology.

* Fairies are often depicted as amoral or having fundamentally different motivations than humans, which is a fit to fungi and its effects on mankind.