New T2K Measurements Of Neutrino Oscillation Parameters

The T2K experiment has used to brute force of running lots of collisions and new clever analysis techniques to come up with its latest measurement of neutrino oscillation parameters. 

Jester retweets physicist Peter Denton who notes in commenting on this paper that:

Their weak evidence for CP violation has decreased somewhat. Was just under 3sigma, now just under 2sigma (depending on the choice of prior).

The bottom line is as follows:

Frequentist and Bayesian analyses are presented, including results on sin2θ13 and the impact of priors on the δCP measurement. Both analyses prefer the normal mass ordering and upper octant of sin2θ23 with a nearly maximally CP-violating phase. 

Assuming the normal ordering and using the constraint on sin2θ13 from reactors, sin2θ23=0.561+0.021−0.032 using Feldman--Cousins corrected intervals, and Δm232=2.494+0.041−0.058×10−3 eV2 using constant Δχ2 intervals. The CP-violating phase is constrained to δCP=−1.97+0.97−0.70 using Feldman--Cousins corrected intervals, and δCP=0,π is excluded at more than 90% confidence level. A Jarlskog invariant of zero is excluded at more than 2σ credible level using a flat prior in δCP, and just below 2σ using a flat prior in sinδCP. 

When the external constraint on sin2θ13 is removed, sin2θ13=28.0+2.8−6.5×10−3, in agreement with measurements from reactor experiments. These results are consistent with previous T2K analyses.

From the body text:

The analysis with (without) the reactor constraint sees a Bayes factor (BF) of 3.35 (1.43) for the upper over the lower θ23 octant; 4.21 (1.83) for the normal over inverted mass ordering; and a combined factor of 1.58 (0.63) for upper θ23 octant and normal ordering. 

When calculating the BFs, the alternate hypothesis is any other combination of octant and mass ordering. Interpreting the largest BFs with the Jeffreys’ scale, there is substantial evidence for the normal ordering when marginalising over the octant, and substantial evidence for the upper octant when marginalising over the mass ordering. In the more recent interpretation of BFs by Kass and Raftery, these both correspond to positive evidence. Importantly, the Jeffreys and Kass–Raftery definitions of “evidence” do not equate to the criteria often used in particle physics. For instance, a probability of 95.4% (“2σ”) is equivalent to a BF of 20.7, which is deemed as “decisive” on the Jeffreys’ scale, and as “strong” on the Kass–Raftery scale.

 

LambdaCDM's Satellite Of Satellite And Weak Feedback Effects Problems

The observed satellite galaxies of satellite dwarf galaxies are one hundred times brighter than LambdaCDM simulations suggest that they should be, according to a new preprint. The conclusion is tentative, because it is based upon only four observations from a sample of 117 satellite galaxies. But no satellite of satellite galaxies this bright at all show up in LambdaCDM simulations, so finding this in a little less than 4% of the satellite galaxies in the sample still has considerable statistical power to show a problem with the LambdaCDM model or the simulation used to determine what it predicts.

In a similar challenge to the simulation based predictions of the LambdaCDM model, a new preprint examining the correlations between supermassive central black hole size, the stellar mass of stars in a galaxy, and the redshift at which the galaxy is observed, suggests that the feedback effects included in recent hydrodynamic simulations of galaxy formation are much too strong. 

This is important because strong feedback effects are one of the main tools used to tune dark matter particle simulations to reproduce simulation results that look like the real world. 

But if the models are greatly overstating the extent of real world feedback effects in galaxies, then this gravely undermines the ability of the dark matter particle theories simulated to accurately describe astronomy observations.

Non-Linear Effects In Many Body Self-Gravitating Systems

Gravity Amplification And Shielding In Complex Many Bodies Systems Analyzed With Newtonian Gravity

In order to to develop good intuition about the emergent non-linear behavior of gravity and its dependence upon the shape of the matter distribution involved in complex many bodied systems (even analyzed with Newtonian gravity alone), there is really no alternative to the difficult work of actually running the numbers in various test cases. This is especially true in cases where the computational crutch of spherically symmetric natter distributions is not available. A new paper does that and its conclusions are intriguing and suggestive.

The language is a bit opaque, but the article is basically explaining in a very sterile and mathematical context, how homogeneous matter arranged in sheet and cylinder shapes can enhance gravitational pulls in a manner akin to dark matter phenomena, and how spherical arrangements of matter can give rise to repulsive effects at large distances phenomenologically similar to dark energy phenomena due to gravitational shielding.

The present work analyzes perturbed potentials due to test mass that is added instantaneously at the center of symmetry of the equilibrium isothermal self-gravitating gases. We examine gravitational amplification in the isothermal sheet, cylinder, and sphere, assuming that the systems are highly collisional and reach a new state of thermal equilibrium after perturbation.

Under the assumptions, the isothermal sheet and cylinder amplify gravitational fields due to test sheet and line masses by 68 % and 53 % maximally. On the one hand, in the isothermal sphere, gravitational fields due to test point mass are amplified oscillatorily with radius and show a repulsive effect at large radii.

Yuta Ito, "Gravitational Amplification of Test-Mass Potential in the Self-gravitating Isothermal Gaseous Systems" arXiv:2303.02631 (March 5, 2023) (Subjects:Astrophysics of Galaxies; Solar and Stellar Astrophysics; Statistical Mechanics).

Can The Shape And Matter Density Of Galaxies Explain Their Flat Rotation Curves With Only Newtonian Gravity?

In the same vein, see also, this new preprint which argues that the right mass density variation with radius and proper consideration of the shape of the matter distribution can give rise to the correct non-Keplerian flat rotation curves in four galaxies considered (a result that I am inclined to be more skeptical of, but do not dismiss out of hand):

Dark matter has been a long-standing and important issue in physics, but direct evidence of its existence is lacking. This work aims to elucidate the mystery and show that the dark matter hypothesis is unnecessary. 

We can nicely reproduce the observed rotation curves using only conventional Newtonian dynamics based on experimental surface brightness profiles of several galaxies. Our success is based on realizing that the mass radial distribution follows a stretched exponential decay with a small exponent over a few hundred kiloparsecs. Our quantitative analysis indicates that for these four example galaxies, there is no need to invoke the hypothetical dark matter presently unknown to humans or the modified Newtonian dynamics (MOND) paradigm.

Jau Tang, Qiang Tang, "Reproducing some observed galactic rotation curves without dark matter or modified Newtonian dynamics" arXiv:2303.02811 (March 6, 2023).

A Conjecture About Early Dark Energy

As an aside, I'll also mention a personal observation not supported by papers of which I am aware.

Modified gravity theories, generically predict the formation of galaxies earlier than in LambdaCDM models.

In Deur's model of gravity, and probably some other gravitational models as well (such as the one discussed above), the same mechanisms that give rise to dark matter phenomena can also lead to what amounts to gravitational shielding that reduces the gravitational pull of the galaxy on objects outside it. This looks observationally, similar to dark energy.

One common approach to trying to resolve the Hubble tension between the apparent Hubble constant in the early universe and the apparent Hubble constant much closer to today, is to hypothesize "early dark energy."

If dark energy phenomena really arise hand in hand with galaxy formation, however, then the early galaxy formation that occurs in modified gravity theories should also give rise to earlier dark energy phenomena. And, since galaxy formation appears to be particular concentrated in the very early universe when there is a sudden burst of galaxy formation that exhausts much of the supply of star forming material almost as soon as it is possible to form galaxies, a burst of early dark energy which would distort the Hubble constant is exactly what one would expect.

Explaining High Energy Neutrino Bursts

Finally, while not strictly on topic, an analysis in a new preprint provides a possible explanation of high energy neutrino bursts seen at at the IceCube neutrino observatory, using only careful consideration of boring well established physics, which had previously puzzled astronomers.

Where Have The Missing Globular Clusters Gone?

A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of member stars. . . . 

Early in the 20th century the distribution of globular clusters in the sky was some of the first evidence that the Sun is far from the center of the Milky Way. Globular clusters are found in nearly all galaxies. In spiral galaxies like the Milky Way they are mostly found in the outer spheroidal part of the galaxy – the galactic halo. 

They are the largest and most massive type of star cluster, tending to be older, denser, and composed of lower abundances of heavy elements than open clusters, which are generally found in the disks of spiral galaxies. The Milky Way has more than 150 known globulars, and there may be many more.

From Wikipedia (star clusters, which are clumps of stars that are smaller than galaxies, are not to be confused with galaxy clusters, which are clumps of many whole galaxies, which together with the "cosmic web" of matter in the universe, are the largest structures in existence in the universe).

We believe that we have a reasonably good understanding of the astrophysical processes that give rise to globular clusters in galaxies. But, globular clusters are observed to be about 23 times less common than simply back of napkin estimates would suggest.

This could be due to "cluster evaporation", due to mergers of globular clusters into other structures or larger globular clusters, or due to other astrophysical processes that have not been accounted for in coming up with this quick estimate of how many of them there should be.

We don't understand the known factors that are in play in astrophysical mass assembly process at this scale well enough to even begin to speculate on any "new physics" effects that could contribute to this discrepancy between theoretical expectations and our astronomy observations.

Planets With Weird Orbits And White Dwarfs Can Be Well Suited For Life

Improved astrophysics and climate modeling, and better telescopes, are allowing us to better understand where there are conditions best suited to life in our galaxy.

It appears that planets with high levels of axial title that have highly elongated orbits may actually be better suited to creating habitable conditions for life than planets with little axial tilt and near circular orbits. 

Obliquity means having an axil tilt relative to the plane in which a planet is rotating.

Eccentricity is the extent to which an elliptical orbit of a planet deviations from being circular.

Planetary obliquity and eccentricity influence climate by shaping the spatial and temporal patterns of stellar energy incident at a planet's surface, affecting both the annual mean climate and magnitude of seasonal variability. 

Previous work has demonstrated the importance of both planetary obliquity and eccentricity for climate and habitability, but most studies have not explicitly modeled the response of life to these parameters. While exaggerated seasons may be stressful to some types of life, a recent study found an increase in marine biological activity for moderately high obliquities <45∘ assuming an Earth-like eccentricity. However, it is unclear how life might respond to obliquities >45∘, eccentricities much larger than Earth's, or the combination of both. 

To address this gap, we use cGENIE-PlaSim, a 3-D marine biogeochemical model coupled to an atmospheric general circulation model, to investigate the response of Earth-like marine life to a large range of obliquities (0-90∘) and eccentricities (0-0.4). 

We find that marine biological activity increases with both increasing obliquity and eccentricity across the parameter space we considered, including the combination of high obliquity and high eccentricity. We discuss these results in the context of remote biosignatures, and we argue that planets with high obliquity and/or eccentricity may be superhabitable worlds that are particularly favorable for exoplanet life detection.

Jonathan Jernigan, Émilie Laflèche, Angela Burke, Stephanie Olson, "Superhabitability of High-Obliquity and High-Eccentricity Planets" arXiv:2303.02188 (March 3, 2023) (published at 944 ApJ 205). https://doi.org/10.3847/1538-4357/acb81c

Another potentially attractive place for life outside Earth is on planets with short period orbits around white dwarf stars - these planets are heated by both the sunlight from its star and by the tidal tug and release on the planet itself (presumably giving rise to geothermal heating) caused by the gravitational interactions of the star and the planet with each other. 

In recent years, there have been a growing number of observations indicating the presence of rocky material in short-period orbits around white dwarfs. 

In this Letter, we revisit the prospects for habitability around these post-main-sequence star systems. In addition to the typically considered radiative input luminosity, potentially habitable planets around white dwarfs are also subjected to significant tidal heating. The combination of these two heating sources can, for a narrow range of planetary properties and orbital parameters, continuously maintain surface temperatures amenable for habitability for planets around white dwarfs over time scales up to 10 Gyr. We show that for a specific locus of orbital parameter space, tidal heating can substantially extend the timescale of continuous habitability for a planet around a white dwarf.

Juliette Becker, Darryl Z. Seligman, Fred C. Adams, Marshall J. Styczinski, "The Influence of Tidal Heating on the Habitability of Planets Orbiting White Dwarfs" arXiv:2303.02217 (March 3, 2023) (Accepted to ApJL).

One factors that makes the existence of life beyond Earth plausible is our detection of complex organic molecules, such as CH₃OH, C₂H₃CN, CH₃OCHO, CH₃COCH₃, aGg'-(CH_2LOH)₂, ¹³CO, CO(2-1), and SiO(5-4), in the matter spewing out of distant galaxies.

This would give the development of life a huge head start if some of those molecules ended up in a place that was otherwise habitable.

Lepton Universality Has Been Reaffirmed; Where Does That Leaves Us?

The latest results reaffirm the conclusion that lepton universality (i.e. the principal that electrons, muons, and tau leptons are identical except for their masses, which is part of the Standard Model of Physics) holds in all interactions experimentally measured to date. Earlier tensions with this conclusion were due to a flawed analysis of the data.

This is particularly a blow to proposals for leptoquarks or vector-like quarks that had been proposed to address the lepton universality violation anomalies that had previously seemed to be present.

The measurement of the R(Xe/µ) ratio in the region p(l)∗ > 1.3 GeV is 1.033 ± 0.010stat ± 0.020 sys which is compatible with the Standard Model prediction of 1.006 ± 0.001 within 1.2σ [13]. At the time of presenting, this result was the most precise branching-fraction based test of lepton flavour universality, now superseded by the latest R(K), R(K∗) measurement from LHCb [14]. Importantly, the R(Xe/µ) result is compatible with the 2019 exclusive result from Belle on R(D∗ e/µ) which was measured to be 1.01 ± 0.01stat ± 0.03sys [15].

From the body text of Priyanka Cheema,"Semileptonic and Leptonic B Physics at Belle II" arXiv:2303.01730 (March 3, 2023) (conference paper in advance of PLR publication).

The Big Picture In High Energy Physics

There is very little room left to deviate from the Standard Model.

The demise of the lepton universality violation anomaly in the experimental data coincides with the probable disappearance of the muon g-2 anomaly due to better calculations of the Standard Model expectation, and data that continues to disfavor and virtually rule out sterile neutrino theories. And, of course, the W boson mass anomaly based upon reanalyzed Tevatron data, which never credible as further analysis is revealing, since it is so out of step with all other high precision measurements made of that particle's mass, in part because the Tevatron data reanalysis used a subtly atypical definition of the W boson mass.

Of these, the experimental data confirmation of the improved lattice QCD calculations of muon g-2 is perhaps the most important, because it is a global measure of low to medium energy scale deviations from the Standard Model, at least up to the energy scales that can be reached by a next generation particle collider.

Similarly, after a decade of Higgs boson experimentation at the Large Hadron Collider (LHC), all of the data is consistent with a Standard Model Higgs boson with a mass of about 125 GeV, although uncertainties in some of the measurements leave wiggle room for alternatives that is narrowed incrementally with the experimental results from each new LHC run of data and is released on an annual basis. There have been no statistically significant signs of additional Higgs bosons. Also, the measured Higgs boson mass is significant because it has a value that prevents a mathematical breakdown of the Standard Model calculations up to the "grand unification theory" (GUT) scale and demands at least "metastable" vacuum (i.e. one where a vacuum collapse of the universe could happen, but is mathematically unlikely to occur on timeframes equal to the current lifetime of the universe).

Slowly but surely, the minimum experimentally supported lifetime of the proton (which is completely stable in the Standard Model) and the frequency with which neutrinoless double beta decay occurs (which is impossible in the Standard Model) are getting ever closer to the Standard Model expectation. The absence of proton decay at the levels observed ruled out the possibility of the simplest grand unified theories of particle physics long ago. 

The non-detection of neutrinoless double beta decay to date (which is a function of Majorana neutrino mass if neutrinos have Majorana mass and does not occur at all if neutrinos have Dirac mass), is so far consistent with neutrino oscillation data suggesting very small (meV scale) mass differences between the three neutrino mass eigenstates, with cosmology data suggesting that the sum of the three neutrino masses is close to the minimum allowed by neutrino oscillation data, and with direct observations of neutrino masses, which while much less strict than those from the other methods mentioned above still constrain the lightest neutrino mass to be significantly less than 1 eV at the 95% confidence level and have best fit values that are smaller than that. 

High energy physics (HEP) is not entirely free of tensions between experiment and Standard Model predicted values, particularly with respect to the consistency of the measured CKM matrix element values with each other (there are nine experimental observables that the Standard Model proposes can be summarized with four parameters that result in unitary weak force flavor transition probabilities for quarks) and when it comes to the properties exotic hadrons. 

But, none of these tensions have a character or magnitude that is widely seen in the HEP-physics community as a lightly sign of beyond the Standard Model physics. 

Alas, however, currently there is also sufficient uncertainty in the two dozen or so experimentally measured parameters of the Standard Model (fifteen masses, four CKM matrix elements, four PMNS matrix elements, and three coupling constants, for a total of 26 parameters, with a few less degrees of freedom since some of these experimentally measured parameters are  functionally related to each other) to distinguish between a variety of "within the Standard Model" additional functional relationships between these parameters that could greatly reduce the number of degrees of freedom in the Standard Model. There are also a couple of experimentally fixed parameters, like Planck's constant, the magnitude of the electron charge, and the speed of light (now used to define units of measurement at a value equal to the most accurate measurements before it was defined definitionally), which while they are not normally considered Standard Model parameters, are necessary to do Standard Model physics.

Most extrapolations of the Standard Model, whose parameters vary with energy scale according to equations called beta functions that can be determined exactly from theory, at very high energies also exclude the impact of unifying the Standard Model with gravity which in a quantum gravity theory should have a subtle by exactly calculable impact on the very high energy behavior of the running of the Standard Model physical constants - which is a known flaw that can be ignored at experimental scale energies given their current precisions.

In short, there is no strong high energy physics motivation at this time for any beyond the Standard Model physics at any kind. Phenomenology efforts to suggest new physics are mostly of the "God of the gaps" variety that exploit experimental results that are fully consistent with the Standard Model but due to their uncertainties, can tolerate moderate deviations from it.

In all probability, the next generation collider will not have high enough energies to detect any new physics that existing experiments don't already strongly disfavor. Existing constraints strongly disfavor new physics at least up to energy scales about a hundred times as great as the LHC. And, there are basically no hints that there will be anything but a new physics desert anywhere between the energies of the LHC and the GUT scale. Nothing we observe positively suggests any need of motivation for new physics at these scales.

We are firmly ensconced in what particle physicists call the "nightmare scenario" - meaning one in which there are no prospects for them to discover new physics in the foreseeable future. 

Really, the best they can do at this point is to better grasp the strong force (QCD) physics of extremely ephemeral and rare exotic hadrons like tetraquarks, pentaquarks, hexaquarks, and so improbably that they are virtually impossible to create top quark hadrons. And, this is mostly a question of more precise measurements and better computing, not of high energy colliders.

Similarly, bridging the gap from hadrons like protons and neutron and pions to the complex assemblies of hadrons found in nuclear physics at a first principles level, is a long term project that we are not particularly close to achieving. But, the laws of physics and relevant fundamental parameters involved are know perfectly for all practical purposes for these kinds of inquiries except for greater precision measurements of the Standard Model parameters (especially the strong coupling constants and some of the quark masses).

There are likewise parameters of neutrino physics to be measured more precisely. But this situation should be dramatically improved in a decade or two by experiments currently in the pipeline.

The Situation In Astrophysics

The situation in astrophysics is quite different. 

On one hand, the standard version of General Relativity with a cosmological constant used in the LambdaCDM Standard Model of Cosmology itself has only two experimentally measured physical constants that go into this law of nature - Newton's constant G (known to parts per 10,000 or so), and the cosmological constant (known much less precisely). The free parameters of the relevant laws of physics are few and don't need a lot of tuning.

But the data tell us that General Relativity with a cosmological constant as conventionally applied with ordinary matter alone is extremely inconsistent with what astronomers observe. There is either something wrong with our theory of gravity as conventionally applied, or there is a lot of dark matter out there.

Astronomy observations fit into the simply six parameter LambdaCDM model (plus a couple of parameters for a massive neutrino extension of it) can fix the relative proportions by mass-energy equivalent of ordinary matter, dark matter, neutrinos, and dark energy (a.k.a. the effects of the cosmological constant) as well as elucidating the topology of the universe (very nearly Euclidian).

But, while LambdaCDM is a decent first order simple approximation of our universe's cosmology, upon closer inspection it starts to fall apart. 

Its simplest form with sterile collisionless dark matter is inconsistent with galaxy dynamics, produces galaxies too late, gets key aspects of galaxy cluster dynamics wrong, and has other more or less independent shortcomings that have been more recently noticed or are more techincal that amount to a dozen or so in all. Simple variations like very light dark matter particles with quantum properties that impact their dynamics and self-interacting dark matter models don't solve all of these problems. Yet, variations from truly sterile dark matter should be observable more directly than the current observations have thus far, and this has greatly narrowed the parameter space for dark matter candidates of almost all of the leading proposals.

Also, in the LambdaCDM model, the Hubble constant should be a constant, and the large scale structure of the universe should be homogeneous, and should be isotropic. But, all three of those assumptions are increasingly in tension with observation. Early 21cm background radiation measurements are inconsistent with dark matter although there have been serious questions posed as to the accuracy of these early observations.

The supersymmetric thermal WIMP candidate for dark matter at the electroweak mass scale, which was the original prime candidate for dark matter, has been basically ruled out. Warm dark matter and sterile neutrinos are likewise in deep trouble. MACHOs (Massive compact halo objects) were ruled out decades ago. Primordial black holes and exotic hadron dark matter particles made out of ordinary matter are also both basically ruled out as well. The viable parameter space for self-interacting dark matter is small and faces serious challenges at solving the problems it was devised to create. 

Also, once you get beyond a single class of sterile dark matter particles, Occam's Razor ceases to favor dark matter particle explanations for dark matter phenomena. If this model doesn't work, dark matter particle theories are introducing not just a new particle but a new force.

The hypothetical X17 boson, which was proposed based upon apparent deviations between the predicted and observed angles of decays in certain nuclear decays that are very hard to model correctly with QCD which is an accurate but low precision part of the Standard Model, even if it existed, wouldn't have the right properties to make it a viable dark matter candidate either. There is very good reason so far to believe that the X17 boson does not exist, although a couple of experiments in the near future will confirm this conclusion.

Axion-like particle (ALP) dark matter is much less well motivated than its proponents claim, because the case that a particle called the axion that was invented to explain why the strong force is indifferent to the direction of time, is weak and ill-motivated. By process of elimination, however, this ultralight bosonic dark matter candidate (whose particles start to approach the minscule mass-energy of gravitons) is perhaps the least definitely constrained or ruled out dark matter particle candidate. To be perfectly honest, however, I haven't followed the various papers narrowing the ALP parameter space - largely because the exclusions in individual experiments and papers are so small, and because they are highly model dependent which makes them hard to compare. Most ALP models, however, propose particles that ought to be relatively easy to detect experimentally with small to medium budget instruments, if you have an experiment tuned to the right ALP properties.

We've now reached the point where gravity based solutions are starting to look good by comparison.

The most well known gravitational tweak, MOND (for modified Newtonian Dynamics) performs remarkably well in the case of the weak field area of galaxy scale systems. It improves on the baryonic matter only dynamics for galaxy clusters and large scale structure but doesn't complete solve those problems. The right way to generalize it relativistically isn't clear, although progress as been made to explain the impossible early galaxy problem and the cosmic microwave background patterns without dark matter particles using relativistic generalizations.

There are also several gravity based approaches, like Deur's general relativity considering self-interactions in weak gravitational fields in large system, Moffat's MOG theories, emergent gravity, conformal gravity, non-local gravity, and some other proposals that call attention to GR effects usually neglected or modify gravity that I've explored less deeply at this blog, which show promise of having easier relativistic generalizations and a broader range of applicability than MOND while reproducing its successes. Many of these are promising but starved for attention, although some early efforts like TeVeS, one of the first relativistic generalizations of gravity, have lost some of their shine.

Other proposals for gravity modification, like massive gravity, are qualitatively strongly disfavored even though they make interesting models to consider to understand relativistic physics.

The good news for astrophysics is that we have a torrent of data gushing in from improved observational instruments (crudely "telescopes" in the most general sense of the word) and improved analytical tools to crunch this big data. So, we can afford to let the data guide the way forward for us and can try all of the approaches to gather different kinds of data in different ways. Gravitational wave detectors are the latest addition to the types of "telescopes" that are out there.

There are also big picture theoretical issues to deal with in astrophysics. Classical GR is not easily made consistent with the quantum physics foundations of the Standard Model, which would be much easier to integrate with a quantum gravity model that either quantized space-time or has a force carrying spin-2 massless gravity, or both. And there are well know practical problems to doing Standard Model type calculations with massless spin-2 gravitons in non-trivial cases, especially at higher energies, because hypothetical gravitons would have self-interactions (more technically, it is a non-linear, non-Abelian theory), and because the naive theory is "non-renormalizable" which is the methodological trick that makes other Standard Model physics problems tractable mathematically.

We have no strong observational cues to tell us if gravity really is quantum  or classical in character, and conventional wisdom holds that distinguishing the differences between the two is very hard, especially outside ultra-strong gravitational fields like those found near black holes and at the time of the Big Bang.

My strong intuition is that just a very subtle tweak from General Relativity as conventionally applied, probably without a cosmological constant, like Deur's work on gravity, can solve all of  the outstanding problems associated with dark matter, dark energy, and more. It can do this without new particles or truly new fields. It can also be much more easily be generalized to a quantum theory than GR with a cosmological constant. 

The calculation issues associated with a non-Abelian, non-renormalizable theory are surmountable as illustrated by the successes of the gravity as QCD squared paradigm and other methodological tools that are just starting to get more attention like lattice quantum gravity, mean field, and scalar field approximations with higher order refinements.

There are likewise good theoretical foundations for most of the open questions in cosmology that arguably aren't even true "scientific" questions that very on philosophy.

We aren't there yet and it make take the deaths of the current generation of scientists to be replaced by a new generation with more up to date assessments of the state of the data and an openness to new world views and paradigms to get there. 

But, I'm an optimist. I've seen glimpses of the promised land from the border of that era and I'm confident that eventually, we will get there, and leave the "dark ages" of astrophysics and cosmology behind us for good, if not in my children's lives, in the lives of my grandchildren.

Another cause for optimism is that even if human physicists with disciplinary sociological blinders the deter them from discovering the truth flounder, sociology-free machine learning approaches to deducting physical laws may make progress where the human scientists fail.

Footnote

The relatively large mass of the Higgs boson, mH≃125 GeV coupled with the (as yet) lack of discovery of any supersymmetric particle at the LHC, has pushed the supersymmetry breaking scale to several TeV or higher.

From here. 

Grapes Were Domesticated In West Asia And The Caucasus 11,000 Years Ago

Contrary to previous understandings, grapes for food and wine were among the first domesticated crops in the Fertile Crescent Neolithic package of crops, and were independently domesticated in two places (the Near East and the Caucasus) with European grapes derived from the Near Eastern domestication. These grapes were then crossed with local wild grape varieties.

A new study reveals that Vitis vinifera was first domesticated around 11,000 years ago, according to a March 2 journal article in Science. The new research, based on genetics data of over 3,500 grape types, suggests that grapevines were first domesticated around 3,000 years prior than previously believed.

Previous archaeological research suggested that Vitis vinifera was first cultivated in the Transcaucasian region around 6,000— to 8,000 years ago, according to the National Library of Medicine.

The study conducted by an international group of researchers also reveals surprising information about the origins of grape domestication. The first cultivated grapevines were traced back to Western Asia and the Caucasus some 11,000 years ago.

Researchers analyzed genetic data from 3,525 domesticated and wild grape varieties to pinpoint the origin of table and wine grapes. It’s believed that the grapevines cultivated in Western Asia traveled to Europe, sparking agricultural pursuits in the area. The data indicates that humans dispersed grapevines along migratory routes into Europe and subsequently created unique grapevines growing both domestically and in the wild.

From here. The journal article and its summary and abstract as well as some key figures from the Supplemental Materials are as follows:

Origins and domestication of grapevines

Humans have extensively shaped the organisms around us through domestication. Although wine and table grapes have been important culturally for thousands of years, their origin has been difficult to pinpoint because of uneven sampling of modern cultivars. Dong et al. analyzed genetic data from about 3500 cultivated and wild grape varieties from around the world. The results of their analysis reveal the effects of climate on historic population sizes, suggest concurrent domestications of wine and table grapes, and identify variants associated with domestication traits such as berry color and palatability. These results increase our understanding of how humans and the environment shaped this domesticated crop. —CNS

Abstract

We elucidate grapevine evolution and domestication histories with 3525 cultivated and wild accessions worldwide. 

In the Pleistocene, harsh climate drove the separation of wild grape ecotypes caused by continuous habitat fragmentation. Then, domestication occurred concurrently about 11,000 years ago in Western Asia and the Caucasus to yield table and wine grapevines. The Western Asia domesticates dispersed into Europe with early farmers, introgressed with ancient wild western ecotypes, and subsequently diversified along human migration trails into muscat and unique western wine grape ancestries by the late Neolithic. 

Analyses of domestication traits also reveal new insights into selection for berry palatability, hermaphroditism, muscat flavor, and berry skin color. These data demonstrate the role of the grapevines in the early inception of agriculture across Eurasia.

Yang Dong, et al., "Dual domestications and origin of traits in grapevine evolution" 379 (6635) Science 892-901 (MARCH 2, 2023). DOI: 10.1126/science.add8655. First Supplemental Materials file here.

The abstract of a related commentary article is as follows:

The domestication of plants that underpin the rise of human civilization is increasingly recognized as a complex interplay of processes across a culturally connected landscape. On page 892 of this issue, Dong et al. reveal more of this complexity by reporting the unraveling of the evolutionary events that led to grape (Vitis vinifera ssp. vinifera) domestication. 

By incorporating the effects of glacial oscillations on biogeographical distributions of the wild progenitor (Vitis vinifera ssp. sylvestris) across Eurasia, they resolved two separate domestication processes from two distinct populations of sylvestris in the Near East and South Caucasus that were separated during the last glacial advance. They found that although the South Caucasus domestication is associated with early winemaking, the origin of wine in Western Europe is associated with cross-fertilization (introgression) between Western Europe’s wild populations and domesticated grapes originating from the Near East that were initially used as food sources.

Surprising Genetic Diversity Among European Hunter-Gatherers

Given the relative homogeneity of Y-DNA haplogroups (predominantly one clade of Y-DNA I) and mtDNA haplogroups (predominantly a few kinds of mtDNA U) among European hunter-gatherers before the Neolithic Revolution arrived there, you might expect a similar lack of diversity in their autosomal DNA. This turns out not to be the reality.

The role of the Italian refuge in during the Upper Paleolithic Ice Age and the repopulation of Europe that followed when it retreated has also been more or less completely upended. It was a dead end and completely replaced in the Mesolithic era.

New ancient DNA reported in an article in Nature reveals that there were great regional variation in the DNA and even phenotypes of European hunter-gatherers, despite the loss of diversity that it suffered during the Upper Paleolithic ice age there from which it was repopulated in the Mesolithic era from relict populations in what turn out to be basically two of three small communities in addition to migration from more distant parts of Southeast Europe and West Asia. 

According to the magazine Science at the link above:

[T]he Gravettians were not a single people. New DNA evidence, published today in Nature, shows Gravettians in France and Spain were genetically distinct from groups living in what is now the Czech Republic and Italy. “What we thought was one homogenous thing in Europe 30,000 years ago is actually two distinct groups,” says Mateja Hajdinjak, a molecular biologist at the Max Planck Institute for Evolutionary Anthropology who was not part of the new study.

The Gravettian data are part of a larger trove of ancient European DNA that reveals striking genetic diversity within apparently unified prehistoric cultures. The sweeping study analyzed 116 newly sequenced genomes and hundreds of previously published ones, ranging from about 45,000 years ago, when the first modern humans reached the continent, to about 6000 B.C.E., and from the Iberian Peninsula to the western steppes of modern-day Russia. . . .

Many of the samples were in poor condition and some came from unusual contexts, like the now-submerged landscape between the British Isles and the Netherlands known as Doggerland. New analytical methods and increasingly powerful DNA sequencing tools enabled researchers to squeeze information from extremely degraded bones and teeth, including some that contained just 1% of their original genetic material. . . .

The DNA also sheds light on what happened to these ancient Europeans when the climate worsened between 25,000 and 19,000 years ago, a time known as the last glacial maximum when much of Northern and central Europe was blanketed in ice more than 1 kilometer thick. Archaeologists had assumed people including the Gravettians retreated into ice-free areas in southern Europe beginning about 26,000 years ago, then filtered back north several thousand years later as the glaciers melted. That scenario appears to hold true in the Iberian Peninsula and the south of France: People living there before the ice reached its peak persist through the worst of the cold spell, then surge back north and east as the continent warms.

But the Italian Peninsula, long thought to have been a relatively secure refuge, showed something different. Despite what looked to archaeologists like evidence of continuous occupation during and after the glacial maximum, DNA reveals the refuge was actually a dead end. “We expected Italy to be a climate refugium, but there’s a sharp and complete turnover—it’s a big surprise,” Posth says. “The Gravettian population completely disappears.” Instead, after the glacial maximum, people in Italy show genetic links to the Near East, suggesting a new population arrived from the Balkans. . . .

About 14,000 years ago, when temperatures across the continent rose sharply in the space of a few centuries, archaeologists recognized cultural changes. But they thought the changes reflected an existing population adapting to hunt in warmer, more heavily forested landscapes. Instead, DNA shows an almost complete population replacement: The people who survived the glacial maximum, known as the Magdalenians, all but vanish and are replaced by populations moving north from postglacial Italy.

The study also looked at the final era of hunter-gatherers in Europe, beginning 10,000 years ago as warming continued to transform the open steppe to dense forests and rich wetlands. Here, again, the genes revealed a surprising wrinkle: Despite broadly similar hunting and gathering lifestyles, people in Western Europe remain genetically distinct from those east of the Baltic Sea.

They even looked different: Genetic data suggest that before the arrival of farmers in northern Europe around 6000 B.C.E., hunter-gatherers in Western Europe had dark skin and light eyes. People in Eastern Europe and Russia, meanwhile, had light skin and dark eyes. Most surprising, despite the lack of geographic barriers between modern-day Germany and Russia, the two groups spent millennia not mingling. “From 14,000 years ago to 8000 years ago, they do not mix at all,” Posth says. But he acknowledges that the team’s samples don’t cover the continent completely, and the likely contact zones—in Poland and Belarus, for example—lack samples. More genetic data from those areas might show the two populations mixing locally.

The source article and its abstract are as follows:

Modern humans have populated Europe for more than 45,000 years. Our knowledge of the genetic relatedness and structure of ancient hunter-gatherers is however limited, owing to the scarceness and poor molecular preservation of human remains from that period. Here we analyse 356 ancient hunter-gatherer genomes, including new genomic data for 116 individuals from 14 countries in western and central Eurasia, spanning between 35,000 and 5,000 years ago. 

We identify a genetic ancestry profile in individuals associated with Upper Palaeolithic Gravettian assemblages from western Europe that is distinct from contemporaneous groups related to this archaeological culture in central and southern Europe, but resembles that of preceding individuals associated with the Aurignacian culture. 

This ancestry profile survived during the Last Glacial Maximum (25,000 to 19,000 years ago) in human populations from southwestern Europe associated with the Solutrean culture, and with the following Magdalenian culture that re-expanded northeastward after the Last Glacial Maximum. 

Conversely, we reveal a genetic turnover in southern Europe suggesting a local replacement of human groups around the time of the Last Glacial Maximum, accompanied by a north-to-south dispersal of populations associated with the Epigravettian culture. From at least 14,000 years ago, an ancestry related to this culture spread from the south across the rest of Europe, largely replacing the Magdalenian-associated gene pool. 

After a period of limited admixture that spanned the beginning of the Mesolithic, we find genetic interactions between western and eastern European hunter-gatherers, who were also characterized by marked differences in phenotypically relevant variants. 

Posth, C., Yu, H., Ghalichi, A. et al. Palaeogenomics of Upper Palaeolithic to Neolithic European hunter-gatherers. 615 Nature 117–126 (March 1, 2023) (open access). https://doi.org/10.1038/s41586-023-05726-0

The paper also notes that:

A companion paper describes genome-wide data of a 23,000-year-old Solutrean-associated individual from southern Iberia that extend the evidence of genetic continuity across the LGM in southwestern Europe.

The reference to this paper is as follows:

Villalba-Mouco, V. et al. A 23,000-year-old southern-Iberian individual links human groups that lived in Western Europe before and after the Last Glacial Maximum. Nat. Ecol. Evol., https://doi.org/10.1038/s41559-023-01987-0 (2023).

The abstract to that open access paper states:

Human populations underwent range contractions during the Last Glacial Maximum (LGM) which had lasting and dramatic effects on their genetic variation. The genetic ancestry of individuals associated with the post-LGM Magdalenian technocomplex has been interpreted as being derived from groups associated with the pre-LGM Aurignacian. However, both these ancestries differ from that of central European individuals associated with the chronologically intermediate Gravettian. Thus, the genomic transition from pre- to post-LGM remains unclear also in western Europe, where we lack genomic data associated with the intermediate Solutrean, which spans the height of the LGM. Here we present genome-wide data from sites in Andalusia in southern Spain, including from a Solutrean-associated individual from Cueva del Malalmuerzo, directly dated to ~23,000 cal yr BP. The Malalmuerzo individual carried genetic ancestry that directly connects earlier Aurignacian-associated individuals with post-LGM Magdalenian-associated ancestry in western Europe. This scenario differs from Italy, where individuals associated with the transition from pre- and post-LGM carry different genetic ancestries. This suggests different dynamics in the proposed southern refugia of Ice Age Europe and posits Iberia as a potential refugium for western European pre-LGM ancestry. More, individuals from Cueva Ardales, which were thought to be of Palaeolithic origin, date younger than expected and, together with individuals from the Andalusian sites Caserones and Aguilillas, fall within the genetic variation of the Neolithic, Chalcolithic and Bronze Age individuals from southern Iberia.

Impossible Early Galaxies Firmly Established

The New Paper In Nature

A new paper in Nature (and its abstract) are as follows (footnotes in the abstract omitted):

Galaxies with stellar masses as high as ~ 10^11 solar masses have been identified out to redshifts z ~ 6, approximately one billion years after the Big Bang. It has been difficult to find massive galaxies at even earlier times, as the Balmer break region, which is needed for accurate mass estimates, is redshifted to wavelengths beyond 2.5 μm. Here we make use of the 1-5 μm coverage of the JWST early release observations to search for intrinsically red galaxies in the first ≈ 750 million years of cosmic history. In the survey area, we find six candidate massive galaxies (stellar mass > 10^10 solar masses) at 7.4 ≤ z ≤ 9.1, 500–700 Myr after the Big Bang, including one galaxy with a possible stellar mass of ~10^11 solar masses. If verified with spectroscopy, the stellar mass density in massive galaxies would be much higher than anticipated from previous studies based on rest-frame ultraviolet-selected samples.

Labbé, I., van Dokkum, P., Nelson, E. et al. "A population of red candidate massive galaxies ~600 Myr after the Big Bang." Nature (February 22, 2023). https://doi.org/10.1038/s41586-023-05786-2 (Open access version available at https://arxiv.org/abs/2207.12446).

Why Is This Paper Important?

The Bottom Line

The paper is notable because it is the most extreme and definitive example of astronomy observations that give rise to the "impossible early galaxy problem" of the LamdaCDM model which is often described as the "Standard Model of Cosmology."

Simply put, the LambdaCDM model predicts that the formation of galaxies of this size should take place far later after the Big Bang than the time frames in which they have been observed by astronomers to exist.

Previous LambdaCDM Galaxy Formation Predictions Compared

One widely accepted prediction was made by astrophysicist Carlos Frenk at a scientific conference in October of 1998 based upon LambdaCDM simulations had been that there would be no galaxies before redshift z=7. This corresponds to a look back time of 13.01 billion years, which is about 770 million years after the Big Bang, which implies that galaxies start forming about 55% to 10% more slowly in the LambdaCDM model than the earliest galaxies must start to form given what has been observed to form so far by the JWST. And, new observations of earlier galaxies over the lifetime of the JWST's mission can only make that gap worse, not weaker, if even earlier galaxies are located.

Like most things in astronomy and cosmology, this LambdaCDM prediction for the time period in which galaxies start to form had a margin of error, but it wasn't a big one and had largely been confirmed by later calculations and simulations made in using the bare LambdaCDM model over the next quarter of a century. And, the LambdaCDM model was so admirable, in part, because it had so few complications and parameters to leave wiggle room in its predictions, and yet was still a good fit to the data for decades.

But now, the new paper in Nature is reporting six reasonably large galaxies at redshifts of z=7.4 ≤ z ≤ 9.1, which at the high end, is much earlier in time than Frenk's LambdaCDM model prediction of z=7. Frenck's 1998 prediction has been only slightly tweaked over the next quarter century and is a precise enough prediction to be significantly different, statistically, from the results announce in the new paper in Nature.

The Impossible Early Galaxies Problem

A published paper from 2016 articulated the "impossible early galaxies" problem as follows:

The current hierarchical merging paradigm and ΛCDM predict that the z∼ 4-8 universe should be a time in which the most massive galaxies are transitioning from their initial halo assembly to the later baryonic evolution seen in star-forming galaxies and quasars. However, no evidence of this transition has been found in many high-redshift galaxy surveys including CFHTLS, Cosmic Assembly Near-infrared Deep Extragalactic Survey (CANDELS), and Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH), which were the first studies to probe the high-mass end at these redshifts. Indeed, if halo mass to stellar mass ratios estimated at lower-redshift continue to z∼ 6-8, CANDELS and SPLASH report several orders of magnitude more M∼ 10^12-13M⊙ halos than is possible to have been formed by those redshifts, implying that these massive galaxies formed impossibly early.

We consider various systematics in the stellar synthesis models used to estimate physical parameters and possible galaxy formation scenarios in an effort to reconcile observation with theory. Although known uncertainties can greatly reduce the disparity between recent observations and cold dark matter merger simulations, there remains considerable tension with current theory even if taking the most conservative view of the observations.

Steinhardt, Charles. L. ; Capak, Peter; Masters, Dan; Speagle, Josh S., "The Impossible Early Galaxies Problem" 824(1) The Astrophysical Journal, article id. 21, 9 pp. (June 2016). DOI: 10.3847/0004-637X/824/1/21 (open access copy available at arXiv:1506.01377).

Thus, there were strong observational hints that there might be an "impossible early galaxy problem", for example, from the Hubble space telescope's observations and other "telescopes" (using the term loosely to describe a variety of astronomy instruments) that can probe highly redshifted objects long before the paper above published yesterday in Nature based upon JWST observations was released.

But, since the James Webb Space Telescope is so much more powerful than any earlier telescope when it comes to probing high redshift objects, what were previously strong hints that there might be big galaxies very soon after the Big Bang turned almost immediately after the JWST came online into multiple clear and unequivocal examples of galaxies of given sizes long before LambdaCDM said that they should exist. The JWST has also seen more galaxies at higher redshifts (i.e. more recently after the Big Bang) than any other "telescopes" before it has (even though it has been on line only briefly). This paper discusses the oldest galaxies seen to date, just 500-700 million years after the Big Bang, that look far more like modern galaxies than the LambdaCDM model should have made possible at this early time period in the universe.

To oversimplify the narrative somewhat, LambdaCDM assumes that in the early universe clumps of dark matter start to accumulate from random differences in matter density, which make it possible for ordinary matter to become concentrated enough to form stars, which in turn end up in clumps of proto-galaxies. These clumps undergoing a "hierarchal" process of repeated mergers and the collide into each other, until they eventually form modern sized galaxies.

The LambdaCDM model, once its six parameters are fitted to astronomy observations, provides data that makes it possible to make reasonable estimates of the rate at which dark matter becomes clumpy, the rate at which stars form, and the rate at which mergers occur, from which it is possible to make reasonable estimates of when galaxies of a certain size ought to appear.

But evidence provided by the JWST, exemplified by this paper with the earliest examples of early galaxies, makes clear that either something about the calculations used to make those predictions, or the LambdaCDM model itself, are wrong in this respect.

The jury is out regarding why galaxies formed much earlier than expected in the LambdaCDM model, even though something is clearly amiss.

What About The LambdaCDM Model Does This Paper Show Is Broken?

One of the main pieces of experimental evidence that previously inspired confidence in the accuracy of the LambdaCDM model was its ability to describe essentially all cosmological scale observations at a large scale structure level with just six astronomy observation fixed parameters, each of which has been measured with some precision.

The LambdaCDM model, once its six parameters are fitted, is, for example, an extraordinarily good match to the observed pattern of the cosmic background radiation (CMB) which came into being during the "recombination era" about 0.38 million years after the Big Bang. (See generally here for the conventional chronology of the universe after the Big Bang in cosmology.) Star and galaxy formation can't happen in any appreciable amount until after the recombination era when ordinary matter and photons (i.e. "radiation") decouple from each other because protons and electrons have been bound together into neutral atoms and the temperature of the universe has cooled sufficiently to allow for greater clumping of matter. So, we think that LambdaCDM gets the "starting line" of the star and galaxy formation process right even after this new paper.

But, the new paper's observations imply that the universe went from giving birth to its first stars after recombination ended, to producing galaxies similar in scale to many galaxies we see today at very low redshifts (about 13,780 million years after recombination), in just 500 to 700 million years. This strongly suggests that some other part of the LambdaCDM model, that crops up later in the history of galaxy formation in the universe and the larger span of the chronology of cosmology, is broken.

Are The Observations In This Paper Credible And Likely To Hold Up?

This result is highly credible because it confirms pre-JWST strong hints that these early galaxies existed. As noted above "high-redshift galaxy surveys including CFHTLS, Cosmic Assembly Near-infrared Deep Extragalactic Survey (CANDELS), and Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH)" were already pointing to this result seven years ago, although much more equivocally than the new data from the JWST does.

The new paper's results are also credible observations because many other JWST observations also identify early galaxies, even though they have not yet been published, have been released to the public, and in some cases have been disclosed in preprints of articles that have been accepted for publication in leading astronomy journals (e.g. here and here and here). So, independent confirmations of the existence of early galaxies established in the Nature article using JWST observation of other candidate galaxies at very high redshifts over the course of the next year or so, are a near certainty.

Another reason that this result is credible is that the impossible early galaxy problem with the LambdaCDM model isn't the only recent crack in that model's predictions.

A full review of discrepancies between astronomy observations and the LambdaCDM model is beyond the scope of this thread. But it suffices to say that there are half a dozen or a dozen or so distinct and independent discrepancies between LambdaCDM model predictions and astronomy observations that are currently being actively investigated in areas that range from galaxy and galaxy cluster observations to different kinds of cosmology scale observations.

Some of those discrepancies may turn out to be experimental methodology issues or require slight tweaks to how the LambdaCDM predictions are calculated that are no big deal in the greater scheme of things. Others discrepancies, however, may turn out to be as serious a challenge to the LambdaCDM model as the impossible early galaxy problem that the new paper in Nature has highlighted.

This is a very different situation than the one that exists for the Standard Model of Particle Physics, where every time a discrepancy or tension between the Standard Model's predictions and experiment has cropped up over the last half century (except with respect to neutrino mass), it has subsequently promptly been ruled out with more experiments and better analysis, and there are only a few weak discrepancies between the Standard Model and experiment currently in play.

So, the scientific community is already primed right now to be more receptive to challenges to the "Standard Model of Cosmology" than it is to tensions between experimental results and the Standard Model of Particle Physics.

Alternatives To The LambdaCDM Model

If the LambdaCDM model is "broken" what alternatives exist to it?

There are multiple possible ways that the LambdaCDM model could be tweaked. One of those many possible alternatives is to look at a gravity based explanation of dark matter phenomena.

Models that attempt to explain dark matter phenomena with a modification to the laws of gravity or how they operate, rather than with dark matter particles, generically predict earlier galaxy formation than the LambdaCDM model does, consistent with the new JWST observations.

For example, galaxies were predicted to form in the time frame now observed by Bob Sanders in October of 1997 in the MOND (modified Newtonian dynamics) paradigm which is the most widely discussed gravitation based approach to explaining dark matter phenomena, even though it is itself a mere phenomenological toy model theory. Sanders predicted that: “Objects of galaxy mass are the first virialized objects to form (by z=10) and larger structure develops rapidly.” This is a little less than 500 million years after the Big Bang.

A JWST observation of a galaxy that may be as earlier as z=9.1 after only an initial quick search shortly after it has become operational, is consistent with that prediction and is at odds with the LambdaCDM prediction.

(This post substantially recaps a Physics Forum post here).

Early Bows and Arrows In Context

Researchers found the telltale stone points in a rock shelter that was inhabited by early modern humans about 54,000 years ago in what is now southern France. Until now, 12,000-year-old wooden artifacts in Northern Europe were the earliest concrete evidence of bow-and-arrow technology on the continent.

The stone points are the earliest evidence in Europe for the use of bows and arrows by early modern humans and suggests that the technology may have given this human lineage an edge over the Neanderthals for hunting prey, the researchers propose in a paper published Feb. 22 in the journal Science Advances. 

. . .

In a study published in the journal Science Advances last year, many of the same researchers reported finding teeth and stone artifacts that showed early modern humans occupied the site between 56,700 and 51,700 years ago — pushing back the earliest known date of the arrival of early modern humans in Europe by about 10,000 years. . . .

The stone and bone points found in the rock shelter at Grotte Mandrin in the Rhône River valley aren't the oldest evidence for bows and arrows anywhere, however; supposed arrowheads, also associated with early modern humans, found in South Africa are more than 70,000 years old.

From Live Science.

The Upper Paleolithic era which corresponds roughly to the period when behaviorally modern human hunter-gatherers appear, long after anatomically modern humans appear ca. 200,000-300,000 years ago. It has conventionally been dated to about 50,000 years ago (reinforced by estimates from contemporary genetics to find a common ancestor for non-African humans). 

But, really start to sea behavioral modernity that distinguished modern humans from other archaic hominins, including fishing implements, bone tools, and artistic work, as well as bows and arrows, at about 70,000 years ago in Africa, which is also around the time that modern humans start to enter Southeast Asia and Australia. 

This was probably a time of expansions of a culture of modern humans that made these behavioral leaps, not just leaving Africa, but also within Africa, that would more or less put in place the demographic make up of Africa until the Holocene era (ca. 10,000 years ago). One major development between the start of behavioral modernity ca. 70,000 years ago, and the Holocene, ca. 10,000 years ago, however, was the domestication of the dog, perhaps 30,000 years ago.

We can say with increasing confidence that some modern humans did leave Africa earlier than 70,000 years ago, reaching the Levant, Arabia, and India. But, the earliest evidence of modern humans in Europe dates only to about 54,000 years ago, modern humans reached the Americas much later, and they reached much of Oceania (beyond the Philippines and Papua New Guinea) only in the Holocene era.

Also, humans were completed banished from most of Europe and Northern and Central Asia in the Ice Age that brought the Last Glacial Maximum ca. 20,000 years ago, except for a handful of refuges in Beringia, Iberia, Italy, the Caucasus Mountains, and perhaps the Altai and even Tibet, only to repopulate these regions afterwards. 

There may have been a tiny and marginally viable population of modern humans in the Americas prior to the Last Glacial Maximum, but they didn't thrive and may even have gone extinct before being replenished the glaciers that encased much of northern North America finally started to subside.