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Earth’s last half-billion years were action-packed. During that time, the climate underwent many changes. There have been changes in ocean levels and ice sheets, changes in the atmosphere’s composition, changes in ocean chemistry, and ongoing biological evolution punctuated with extinction events.

A record of Earth’s temperature over the last 485 million years is helping scientists understand how it all played out and illustrating what could happen if we continue to enrich the atmosphere with carbon.

The new temperature record is presented in research titled “A 485-million-year history of Earth’s surface temperature.” It’s published in Science, and the lead author is Emily Judd. Judd is from the Department of Paleobiology at the Smithsonian National Museum of Natural History.

“This research illustrates clearly that carbon dioxide is the dominant control on global temperatures across geological time.”

Jessica Tierney, University of Arizona

The new historical temperature comes from an effort named PhanDA, which stands for Phanerozoic Data Assimilation. PhanDA combined data from climate models with data from geology to determine how the climate has changed over the last nearly 500 million years. The Phanerozoic is Earth’s current geological eon, and it started 538.8 million years ago. It’s known for the proliferation of life, and its beginning is marked by the appearance of the hard shells of animals in the fossil record.

PhanDA is a mix of data and prior simulations by the scientific community. “This approach leverages the strengths of both proxies and models as sources of information, providing an innovative way to explore the temporal and spatial patterns in Earth’s climate across the Phanerozoic,” the researchers write in their paper. It allowed the researchers to reconstruct the climate more thoroughly.

This figure illustrates the data used to create PhanDA. A shows the temporal distribution of proxy data used in PhanDA. B shows the spatial distribution. C shows the range (gray band) and median (black line) of GMSTs within the prior model ensemble for each assimilated stage. Image Credit: Judd et al. 2024.

“This method was originally developed for weather forecasting,” said Judd. “Instead of using it to forecast future weather, here we’re using it to hindcast ancient climates.”

We’re blowing by atmospheric carbon benchmarks, and the Earth is warming. We’re now at over 420 ppm of CO2. The best way to understand what’s coming our way is by looking at the past.

“If you’re studying the past couple of million years, you won’t find anything that looks like what we expect in 2100 or 2500,” said co-author Scott Wing, the curator of paleobotany at the National Museum of Natural History. Wing’s research focuses on the Paleocene–Eocene Thermal Maximum, a period of dramatic global warming 55 million years ago. “You need to go back even further to periods when the Earth was really warm, because that’s the only way we’re going to get a better understanding of how the climate might change in the future.”

During the Paleocene-Eocene Thermal Maximum (PETM), a massive amount of carbon was emitted into the atmosphere and the oceans. The Earth’s temperature reacted swiftly, warming by between five and eight degrees Celsius in only a few thousand years. While a few thousand years might seem long compared to a human lifetime, it’s nearly instantaneous for the climate of an entire planet. It likely triggered the massive extinction of between 35% to 50% of benthic life. Fossils show that during this time, sub-tropical planets grew in the polar regions.

Many scientists think the PETM is the best analogue for what we’re facing today. No matter what we do with our emissions in the next several decades, much of the carbon humanity has released into the atmosphere since the Industrial Revolution will persist in the atmosphere for thousands of years.

Earth’s reconstructed Global Mean Surface Temperature for the past 485 million years. Blue rectangles show the maximum latitudinal ice extent, and orange dashed lines show the timing of the five major mass extinctions of the Phanerozoic. The five orange fishbone symbols mark mass extinctions. Image Credit: Judd et al. 2024.

PhanDA illustrates the unbreakable link between carbon and global warming. According to co-author Jessica Tierney, a paleoclimatologist at the University of Arizona, the link between the climate and carbon is undeniable. “This research illustrates clearly that carbon dioxide is the dominant control on global temperatures across geological time,” said Tierney. “When CO2 is low, the temperature is cold; when CO2 is high, the temperature is warm.”

While proof of the link between climate and carbon isn’t new, this long timeframe drives it home. “The consistency of this relationship is surprising because, on this timescale, we expect solar luminosity to influence climate,” the authors write. “We hypothesize that changes in planetary albedo and other greenhouse gases (e.g., methane) helped compensate for the increasing solar luminosity through time.”

Overall, Earth’s global mean surface temperature (GMST) ranged from 11° to 36°C during the Phanerozoic, a larger range than previously thought. It also shows that greenhouse climates were hotter than thought. The largest temperature swings were in the high latitudes, but tropical temperatures ranged from 22 C to 42 C. This goes against the idea that the tropics have a fixed upper limit and shows that life must have evolved to survive in those higher temperatures.

The research also shows that our current climate is actually cooler than the climate through most of the Phanerozoic. Technically, Earth is in an ice age right now, though the ice is receding and has been for thousands of years. Earth’s current GMST is 15 Celsius, lower than during most of the Phanerozoic.

But while that may sound comforting, it’s not. It’s the rate of change in the GMST that’s dangerous. Our GHG emissions are warming the planet faster than at any time during the Phanerozoic.

“Humans, and the species we share the planet with, are adapted to a cold climate,” Tierney said. “Rapidly putting us all into a warmer climate is a dangerous thing to do.”

This figure from the published research shows the climate states through the Phanerozoic. D shows the latitudinal surface air temperature gradient associated with each of the climate states. Coloured bands show the 16th to 84th percentiles, and coloured lines show the median value. Image Credit: Judd et al. 2024.

While PhanDA is generally in agreement with previous climate reconstructions, it deviates in some ways. For example, cold climate periods don’t always coincide with glaciation and ice ages. Earth’s surface is ever-changing, and that can make some conclusions difficult to reach. “Many of the traditional glacial indicators can have nonglacial origins, complicating the interpretation of the rock record, and limited outcrop of older rocks and poor age control can make it difficult to discern between isolated alpine glaciers and widespread ice sheets,” the authors explain.

But that doesn’t take much away from PhanDA. It strengthens our understanding of climate and carbon.

This figure illustrates the undeniable relationship between atmospheric carbon and a warming climate. B shows PhanDA GMST versus CO2, colour-coded by geologic era. The black dashed line shows the York regression, a statistical method used to draw a straight line between data points with some uncertainties. C shows the CO2 ranges for each of the defined climate states. Image Credit: Judd et al. 024.

Shockingly, the work suggests that Earth’s climate is even more sensitive to CO2 than some current models show.

“PhanDA GMST exhibits a strong relationship with atmospheric CO2 concentrations, demonstrating that CO2 has been the dominant force controlling global climate variations across the Phanerozoic,” the authors write in their conclusion.

The post From Frozen to Sweltering: Earth’s Climate Over the Last 485 Million Years appeared first on Universe Today.

Archaeologists have used AI to discover hundreds of large-scale drawings depicting figures like llamas, decapitated human heads and killer whales armed with knives

Engineers have designed an innovative tubular structural system that can be packed flat for easier transport and pop up into strong building materials. This breakthrough is made possible by a self-locking system inspired by curved-crease origami -- a technique that uses curved crease lines in paper folding.

Scientists who arranged for 48 human bioengineered heart tissue samples to spend 30 days at the International Space Station report evidence that the low gravity conditions in space weakened the tissues and disrupted their normal rhythmic beats when compared to earth-bound samples from the same source.

Researchers have created a computer program that can unravel the mysteries of how proteins work together -- giving scientists valuable insights to better prevent, diagnose and treat cancer and other diseases. The tool uses artificial intelligence (AI) to build the three-dimensional atomic structure of large protein complexes.

New statistical models based on rigorous physiological data from more than 100 surgeries provide objective, accurate measures of 'nociception,' the body's subconscious perception of pain.

Interacting with animals seems to provide emotional support to young people with a serious illness, even when the contact is via letters and not face to face

Given that most of the world doesn’t want Israel to win any wars, it’s natural that the media is full of criticisms of Israel for exploding hundreds of beepers (and some walkie-talkies) that were in the hands of Hezbollah operatives.  (You can see critiques, for example, here, here, and here, and the beeper attacks were also criticized by the miscreant AOC, who never said word one about Hezbollah violating international law with its repeated rocket attacks or about ther death of 12 Druze Israeli children from those rockets.

Israel’s pager attack in Lebanon detonated thousands of handheld devices across of a slew of public spaces, seriously injuring and killing innocent civilians.

This attack clearly and unequivocally violates international humanitarian law and undermines US efforts to prevent a…

— Alexandria Ocasio-Cortez (@AOC) September 18, 2024

Further, beepers were in fact invented by a Jew, which I suppose makes them doubly nefarious.

At any rate, I just discovered that Sam Harris has a Substack site, and I got a subscription by begging for it. Sam, as you may recall, wrote after October 7 a terrific and eloquent criticism of Hamas terrorism as being deeply immoral. It’s one of the best short pieces he’s written.

Now Sam’s taken up the Grim Beeper episode, and defends it as a precision targeted operation that had almost no “collateral damage”.  Those who say it was a war crime or violation of humanitarian principles of war are simply off the rails. Click below (I think the article is free), or you can find the piece archived here. 

An excerpt (long one):

Thousands of electronic pagers—and later, hand-held radios—exploded simultaneously, killing dozens and injuring vast numbers of jihadists. This attack, the ingenuity of which cannot be denied, has been widely criticized as a dangerous escalation, as a breach of the rules of war, and most ludicrously, as an act of terrorism.

But if this Trojan Horse operation was as precise as it appears to have been, then it ranks among the most ethical acts of self-defense in memory. There are no “innocent” members of Hezbollah—whose only contributions to human culture have been the ruination of Lebanon and the modern evil of suicide bombing. This Iranian proxy has been firing rockets into northern Israel since October 8th, in response to… well, nothing at all. Israel’s occupation of Lebanon ended a quarter century ago.

If the Israelis managed to target members of Hezbollah by turning their personal electronic equipment into bombs—without seeding such bombs indiscriminately throughout Lebanon—then they achieved a triple victory. First, they killed or maimed the very people who have been trying to murder them, and who have displaced 70,000 innocent Israeli civilians from their homes. Second, they marked actual jihadists among the survivors, presumably making them easier to capture or kill in the future—and, one can only hope, reducing their status in Lebanese society. And third, they have stripped away some of the glamour of jihad. The promise of Paradise is one thing; the prospect of living without fingers or eyes is another.

Again, the righteousness of this attack depends on whether it was as targeted as it seems. Tragically, four children are reported to have been killed. However, compared to almost any other military operation, this act of mass sabotage appears to have produced very few unintended deaths. It is an example of exactly the sort of calibrated violence that Israel’s critics claim to support. And it has delivered a profound psychological blow to one of the most ruthless jihadist organizations on Earth.

Of course, many assert that any acts of retaliation, however precise, simply breed more violence. They seem to believe that pacifism, in some form, must be the ultimate answer to Israel’s existential concerns. After all, how else will the killing stop?

Sam then goes after pacifism with an argument reminiscent of Orwell’s, and in general I agree. Pacificm is injurious to the moral side in a just war, like WWII or, in this case, the war of Israel against Hezbollah. But, as a CO, I would not be able to fight in a war I consider unjust, such as that in Vietnam (my college term paper in Ethics was on figuring out what I considered to be a just war, and I used that paper as supporting evidence in my CO application.)

Sam ends with a question:

. . . . If you are uncomfortable with an operation that precisely targeted a group of jihadists who aspire to commit an actual genocide, just what sort of self-defense on Israel’s part would you support?

It’s an honest question, but of course for many NO form of self-defense is justifiable when it’s Israel defending itself.

Today’s photos come from Uwe Mueller in Deutschland. Mueller’s captions and IDs are indented, and you can enlarge the photos by clicking on them:

Here is a collection of insects that I shot in the Bergisches Land of Germany. I’m not that familiar with insects so it is possible (in fact very likely) that I committed errors with their naming. Any corrections will be appreciated.

A Globe wanderer dragonfly (Pantala flavescens) that landed on my balcony and didn’t mind when I took multiple shots of her from close proximity. According to Wikipedia it can be found all around the globe but is quite rare in Europe and made its first appearance in Germany only in 2019.

A Migrant hawker (Aeshna mixta) in flight. These is one of the main dragonfly species that I see at our local pond. Its german name is Herbst-Mosaikjungfer which translates to Fall mosaic virgin, whatever the reason behind this name is:

A Western honey bee (Apis mellifera):

Not too sure if this is a Common wasp (Vespula vulgaris) or a German wasp (Vespula germanica). On another shot I could see one dot on its head. According to Wikipedia the German wasp should have three dots so I guess it is the Common wasp then:

A Polygonia c-album which I find is a strange name for a butterfly:

Another insect that I wasn’t able to identify. Some kind of predatory fly that is eating another insect:

An ant (Tetramorium noclueensis):

An insect identification website told me that this is a fruit fly (Drosophila sp.). However, is it? I shot this in our local forest and the fruit flies that I sometimes find in my kitchen during the fruit season are usually a lot smaller:

Observations confirm astronomers' expectation that early-Universe quasars formed in regions of space densely populated with companion galaxies. DECam's exceptionally wide field of view and special filters played a crucial role in reaching this conclusion, and the observations reveal why previous studies seeking to characterize the density of early-Universe quasar neighborhoods have yielded conflicting results.

An octopus will work with several different species of fish to find and catch prey - and punch those that aren't helping

Astronomer Jo Dunkley is planning to use the Simons Observatory to snare evidence for inflation, the theory that the universe expanded at incredible speed after its birth

Andrew Sullivan’s latest column (click first headline to read, but I couldn’t find an archived version) is a strange one.  His main point—that “progressives’ think that some scientific research should be ignored because it flouts their ideological conventions—is a good one, and one that Luana Maroja and I made before.

In this piece, Sullivan attacks three of these issues: assumption that there are no evolved differences among races, especially in intelligence; that gender reassignment may not always be a good thing; and, an issue I’ve mentioned before, the falsity of recent claims that black newborns have a higher mortality when taken care of by white rather than black physicians (this fact, falsely imputed to racism, actually reflects that underweight black newborns are preferentially given to the care of white doctors).  Sullivan’s conclusion is that science should proceed untrammeled by ideology:

Let science go forward; may it test controversial ideas; may it keep an open mind; may it be allowed to flourish and tell us the empirical truth, which we can then use as a common basis for legitimate disagreements. I think that’s what most Americans want. It’s time we stood up to the bullies and ideologues and politicians who don’t.

He’s right, but he also commits what I see as a serious error.  He describes recent studies by a crack geneticist (David Reich at Harvard) and his colleagues, studies showing that there has been natural selection on several traits within Eurasian “populations” in the last 8000 years. But then Sullivan extrapolates from those results to conclude there must then have been natural selection causing differences among populations.  Now we know that the latter conclusion is true for some traits like skin pigmentation and lactose intolerance, but we can’t willy-nilly conclude from seeing natural selection within a population to averring that known differences among populations in the same trait have diverged genetically via natural selection rather by culture culture (or a combination of culture and selection).

The hot potato here, of course, is IQ or “cognitive performance.”  This does differ among races in the U.S., but the cause of those differences isn’t known (research in this area is pretty much taboo).So even if there’s been natural selection on cognitive performance within Eurasians, as Reich et al. found, one isn’t entitled to conclude that differences among populations (or “races”, a word I avoid because of its historical misuse) must therefore also reflect genetic results of natural selection.

Here’s what Sully says, and basis it on the bioRχiv paper by Akbari et al. (Reich is the senior author) which you can access by clicking below.

Sullivan (bolding is mine):

But how have human sub-populations changed in the last, say, 10,000 years? A new paper, using new techniques, co-authored by David Reich, among many others, shows major genetic evolution in a single human population — West Eurasians — in the last 14,000 years alone. The changes include: “increases in celiac disease, blood type B, and a decline in body fat percentage, as farming made it less necessary for people to store fat for periods without any food.” Among other traits affected: “lighter skin color, lower risk for schizophrenia and bipolar disease, slower health decline, and increased measures related to cognitive performance.” Guess which trait is the controversial one.

The study was able, for the first time, to show

a consistent trend in allele frequency change over time. By applying this to 8,433 West Eurasians who lived over the past 14,000 years and 6,510 contemporary people, we find an order of magnitude more genome-wide significant signals than previous studies: 347 independent loci with >99% probability of selection.

Not just evolutionary change in the last 14,000 years — but “an order of magnitude” more than any previous studies had been able to show. Gould was not only wrong that human natural selection ended 50,000 years ago — but grotesquely so. Humans have never stopped evolving since we left Africa and clustered in several discrete, continental, genetic sub-populations. That means that some of the differences in these sub-populations can be attributed to genetics. And among the traits affected is intelligence.

The new study is just of “West Eurasians” — just one of those sub-populations, which means it has no relevance to the debate about differences between groups. But it is dramatic proof of principle that human sub-populations — roughly in line with what humans have called “races” — can experience genetic shifts in a remarkably short amount of time. And that West Eurasians got suddenly smarter between 10,000 and 5,000 years ago and then more gradually smarter since.

If the results have no relevance to differences between groups, then why in the next sentence does he extrapolate the results to differences between sub-populations or “races”?

Well, yes, Sullivan does indeed admit that the West Eurasian study (below), showing selection within tjat group, can’t be extrapolated to differences between groups.  But he does so anyway, saying that “it is the dramatic proof of a principle that human sub-populations — roughly in line with what humans have called “races” — can experience genetic shifts in a remarkably short amount of time.

Well, no, it doesn’t really “prove” that.  It’s surely true that 1) if two or more populations show genetic variation in a trait and 2) natural selection ACTS DIFFERENTIALLY in those different populations (or “races” or “subpopulations”), then yes, selection can in principle cause genetic differences among populations.  But this is not an empirical observation, but a hypothetical scenario. It’s almost as if Sullivan wants to use within-population data to show that differences among populations (especially in “cognitive performance”) must, by some kind of logic rather than empirical analysis, also be genetically based, and instilled by natural selection. But he is talking about what is possible, not what is known.

The relevant article below, which is somewhat above my pay grade, shows that Reich’s group used a combination of ancient and modern DNA to look for coordinated changes in the sequences of genes  involved in the same trait. Using GWAS analysis (genome-wide association studies), investigators can find out which segments of the genome are associated with variation in various traits within a population.  This way, for example, you can find out which areas of the genome (I believe there are about 1200) vary in a coordinated fashion with variation in an individual’s smarts (they use “educational attainment” as a surrogate for intelligence.

Click title to read:

Knowing this association, you can then compare the bits of the genome in ancient DNA associated with various traits like those listed above, and then estimate a) whether the bits of the genome that are jointly associated with variation in a trait measured today have changed in a coordinated way (i.e., have the genes affecting body fat in a population today changed over the last 8000 years in a coordinated way, with a decrease in those gene variants associated with higher body fat?); and b) the likelihood that natural selection has changed those bits over time.

Although we don’t, for example, know the “educational attainment” of ancient people, we can see that gene variants associated with higher attainment have increased by positive selection in the past few thousand years, implying that the Eurasian population has gotten smarter.  It’s thus fair to conclude that, within the study population,  there was selection for higher cognitive ability, known to be associated with educational attainment.  Here, for example, are two findings of selection from the paper:

CCR5-Δ32: Positive selection at an allele conferring immunity to HIV-1 infection (panel 7)

The CCR5-Δ32 allele confers complete resistance to HIV-1 infection in people who carry two copies43–45. An initial study dated the rise of this allele to medieval times and hypothesized it may have been selected for resistance to Black Death46, but improved genetic maps revised its date to >5000 years ago and the signal became non-significant47,48. We find that the allele was probably positively selected ∼6000 to ∼2000 years ago, increasing from ∼2% to ∼8% (s =1.1%, π=93%). This is too early to be explained by the medieval pandemic, but ancient pathogen studies show Yersinia was endemic in West Eurasia for the last ∼5000 years49–51, resurrecting the possibility that it was the cause, although other pathogens are possible.

Selection for light skin at 10 loci (panels 8-17).

We find nine loci with genome-wide signals of selection for light skin, one probable signal, and no loci showing selection for dark skin.

Depending on which level of stringency you want to use to identify natural selection on bits of the DNA, Reich’s group found between 300-5,000 “genes” (DNA bits) that have undergone positive or negative natural selection in our ancestors. But remember this: when you are talking about selection on traits, we didn’t KNOW the traits of our ancestors (like “intelligence” or “propensity to smoke” in our ancestors. Instead, what we see is that gene variants affecting those traits in modern populations have changed over time from ancient populations, with gene variants affecting a given trait changing in a coordinated way (i.e., different bits of DNA associated today with “higher intelligence” have generally increased over time).

Below is a figure from the paper showing 12 traits that have coordinated changes in the genes affecting them. Click to enlarge, and note that the traits vary from darker skin color (DNA bits associated with darker skin color declined in frequency, implying selection for lighter skin), waist to hip ratio (genes affecting this ratio declined in frequency), and both “intelligence” and “years of schooling” (both showing strong increases in “smart” DNA over the last 8,000 years).  It’s a clever analysis.

From paper: Figure 4: Coordinated selection on alleles affecting same traits (polygenic adaptation). The polygenic score of Western Eurasians over 14000 years in black, with 95% confidence interval in gray. Red represents the linear mixed model regression, adjusted for population structure, with slope γ. Three tests of polygenic selection—γ, γsign, and rs—are all significant for each of these twelve traits, with the relevant statistics at the top of each panel.

This is a lovely study (it needs vetting, of course, as this is a preprint), but doesn’t buttress Sullivan’s conclusion that changes within a group wrought by natural selection, such as the changes above, mean that differences between populations must also have been caused by natural selection. That’s simply a mistake, or a fallacy resting on confirmation bias. Sullivan insists, though, that he’s just interested in what the facts are, and those facts must play into any societal changes we want to make. (He’s sort of right here, but not completely, but I’ve discussed this issue in a WaPo book review.)

Sullivan:

Why do I care about this? It’s not because I’m some white supremacist, or Ashkenazi supremacist, or East Asian supremacist. It’s because I deeply believe that recognizing empirical reality as revealed by rigorous scientific methods is essential to liberal democracy. We need common facts to have different opinions about. Deliberately stigmatizing and demonizing scientific research because its results may not conform to your priors is profoundly illiberal. And, in this case, it runs the risk of empowering racists. As Reich wrote in his 2018 op-ed:

I am worried that well-meaning people who deny the possibility of substantial biological differences among human populations are digging themselves into an indefensible position, one that will not survive the onslaught of science. I am also worried that whatever discoveries are made — and we truly have no idea yet what they will be — will be cited as “scientific proof” that racist prejudices and agendas have been correct all along, and that those well-meaning people will not understand the science well enough to push back against these claims.

Scientific illiberalism is on both sides. The denial of natural selection by creationists and the denial of carbon-created climate change by some libertarians is damaging to any sane public discourse, but so too is the denial of any human evolution for 50,000 years by critical race theorists and their Neo-Marxist and liberal champions.

Okay, but I wish he’d been a bit more explicit about the limitations of Reich’s study for concluding things about selection among populations or “races”.  Note, though, that he chastises both Left and Right for committing scientific “illiberalism.”

One area in which his conclusions seem more sound, however, involves gender and trans issues:

You see this [scientific illiberalism] also in the left’s defense of “no questions asked” gender reassignment for autistic, trans, and mainly gay children on the verge of puberty. The best scientific systematic studies find no measurable health or psychological benefit for the children — and a huge cost for the thousands of gay or autistic or depressed kids who later regret destroying their natural, functioning, sexed bodies. And a new German-American study has just “found that the majority of gender dysphoria-related diagnoses, including so-called gender incongruence, recorded in a minor or young adult’s medical chart were gone within within five or six years.” Yet the entire US medical establishment refuses to budge.

I should say that my own priors might also need checking. Maybe some, well-screened kids would be better off with pre-pubertal transition. Right now, we just don’t know. That’s why I favor broad clinical trials to test these experiments, before they are applied universally, and why I believe kids should have comprehensive mental health evaluations before being assigned as trans. And yet, as I write, such evaluations are being made illegal in some states, and gay kids are being mutilated for life before puberty, based on debunked science — and Tim Walz and the entire transqueer movement is adamant that no more rigorous research is needed.

Agreed!  I think that Sullivan should have added that studies do show that adults accrue overall benefits from changing gender (at least that’s what I remember). If that’s the case, then he’s made another omission that. if admitted would strengthen his credibility (always admit the caveats with your conclusions!) But I think he’s dead-on right about affirmative therapy for minors.

(h/t: Christopher)

CRISPR-Cas is used broadly in research and medicine to edit, insert, delete or regulate genes in organisms. TnpB is an ancestor of this well-known 'gene scissor' but is much smaller and thus easier to transport into cells. Using protein engineering and AI algorithms, researchers have now enhanced TnpB capabilities to make DNA editing more efficient and versatile, paving the way for treating a genetic defect for high cholesterol in the future.

If there really are advanced alien civilizations out there, you’d think they’d be easy to find. A truly powerful alien race would stride like gods among the cosmos, creating star-sized or galaxy-sized feats of engineering. So rather than analyzing exoplanet spectra or listening for faint radio messages, why not look for the remnants of celestial builds, something too large and unusual to occur naturally?

The most common idea is that aliens might build something akin to a Dyson sphere. In their need for more powerful energy sources, an advanced civilization might harness the entire output of a star. They wrap a star within a sphere to capture every last photon of stellar energy. Such an object would have a strange infrared or radio spectrum. An alien glow that is faint and unique. So astronomers have searched for Dyson spheres in the Milky Way, and have found some interesting candidates.

One major search was known as Project Hephaistos, which used data from Gaia, 2MASS, and WISE to look at five million candidate objects. From this they found seven unusual objects. They appear to be M-type red dwarfs at first glance, but have spectra that don’t resemble simple stars. This kind of star-like infrared object is exactly what you’d expect from a Dyson sphere. But of course extraordinary claims require extraordinary evidence, and that’s where things get fuzzy.

Almost immediately after the paper was published, other astronomers noted that the seven objects could also be hot Dust-Obscured Galaxies, or hotDOGs. These are quasars, so they appear star-like, but are obscured by such a tremendous amount of dust that they mostly emit in the infrared. And their spectra can be quite different from a M-type star. So the challenge is to distinguish between a hotDOG and a Dyson sphere. Which is where a new paper on the arXiv comes in.

Rather than trying to specifically distinguish between the two, the authors instead look at the distribution of known hotDOGS. They found that statistically about 1 in 3,000 quasars are of the hotDOG type, so that a broad search for Dyson spheres would likely include some dusty quasars. The authors go on to note that any civilization powerful enough to build star-scale structures would also have the ability to obscure their infrared signal. We can’t simply assume that aliens would build a Dyson sphere in such an obvious way. Overall, the authors argue, the seven candidate superstructures can be accounted for by hotDOGs and other phenomena, thus there is currently no clear evidence for alien superstructures.

Reference: Suazo, Matías, et al. “Project Hephaistos–II. Dyson sphere candidates from Gaia DR3, 2MASS, and WISE.” Monthly Notices of the Royal Astronomical Society 531.1 (2024): 695-707.

Reference: Blain, Andrew W. “Did WISE detect Dyson Spheres/Structures around Gaia-2MASS-selected stars?.” arXiv preprint arXiv:2409.11447 (2024).

The post Those Aren't Dyson Spheres, They're HotDOGs appeared first on Universe Today.

Ancient DNA extracted from layers of sediment in a Czech forest shows how a drop in biodiversity coincided with a shift to pig herding about 4000 years ago

An atlas doesn’t seem to be an essential item in cars these days but think about them and most people will think about distances. An atlas of the stars not only covers distances but must also take into account time too. The Andromeda galaxy for example is so far away that its light takes 2.5 million years to reach us. A team of researchers have now built a catalogue that contains information on millions of galaxies including their distance and looks back in time up to 10 billion years!

Like anything that has – hmmmm lots of stuff, there are always catalogues to capture information about them. Astronomy is no different and there are plenty of catalogues; Messier, New General, Second Cambridge Catalogue of Radio Sources and the Two Micron All Sky Survey, the list goes on. Now a new catalogue has been created to provide information on millions of distant galaxies. It’s been created by a collaboration of organisations led by the Institute of Space Sciences as a result of the Physics of the Accelerating Universe Survey (PAUS.)

This new NASA/ESA Hubble Space Telescope shows Messier 96, a spiral galaxy just over 35 million light-years away in the constellation of Leo (The Lion). It is of about the same mass and size as the Milky Way. It was first discovered by astronomer Pierre Méchain in 1781, and added to Charles Messier’s famous catalogue of astronomical objects just four days later. The galaxy resembles a giant maelstrom of glowing gas, rippled with dark dust that swirls inwards towards the nucleus. Messier 96 is a very asymmetric galaxy; its dust and gas is unevenly spread throughout its weak spiral arms, and its core is not exactly at the galactic centre. Its arms are also asymmetrical, thought to have been influenced by the gravitational pull of other galaxies within the same group as Messier 96. This group, named the M96 Group, also includes the bright galaxies Messier 105 and Messier 95, as well as a number of smaller and fainter galaxies. It is the nearest group containing both bright spirals and a bright elliptical galaxy (Messier 105).

Over a period of 200 nights between 2015 and 2019, the teams embarked on their survey using the PAUCAM mounted upon the William Herschel Telescope (WHT) in La Palma. The camera is mounted at the prime focus of the WHT giving it a whopping 1 degree field of view. There are filter trays in front of the CCDs with 42 narrowband filters ranging from 4400 to 8600 angstroms. The team used the different filters to image the same field numerous times. The light from more distant objects will be shifted toward the red end of the spectrum and the multiple images of the same field will enable distance calculations to be made.

The William Herschel Telescope, part of the Isaac Newton group of telescopes, located on Canary Island. Credit: ing.iac.es

Overall, the survey covers 50 square degrees on the sky. To put that into context, the full moon measures half a degree across so the full survey maps out an area of sky equivalent to about 250 full moons. Having analysed the full set of images, the catalogue that has been developed includes data for 1.8 million objects which will be the foundations for astronomers to better understand the structure of the Universe. 

Understanding the structure of the universe is to understand the distribution of dark matter and dark energy. Dark energy is thought to make up 70 percent of the Universe but we still don’t know what it is. We can see its effect in the accelerated expansion of the Universe but its nature remains a mystery to us. The new survey will help to shine a light on dark energy with its comprehensive data set of galaxies that span more than 10 billion light years. 

This multiwavelength image of the Cloverleaf ORC (odd radio circle) combines visible light observations from the DESI (Dark Energy Spectroscopic Instrument) Legacy Survey in white and yellow, X-rays from XMM-Newton in blue, and radio from ASKAP (the Australian Square Kilometer Array Pathfinder) in red. X. Zhang and M. Kluge (MPE), B. Koribalski (CSIRO)

The results are a significant step forward in research into the cosmic distance scale and offers an extensive catalogue of photometric redshift measurements as they appeared billions of years ago. Over the months that follow, the team are planning on exploring galaxy clustering and galaxy shapes to help understand the evolution of the universe. 

Source : New cosmic distance catalogue to unlock the mysteries of Universe formation

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