Jameela Jamil has dubbed the British 'the most evil people in history' based on the history of the Empire. Read this point-by-point rebuttal by Maxi Gorynski. On the contrary, he says, our Empire was one of the most benign
The Scientific Revolution was significantly influenced by Christian philosophers and scientists, particularly Francis Bacon, who emphasized empirical methods and a rational Creator. The integration of faith and reason laid the foundational principles of modern science. The laws of the physical universe never change and are discoverable using the scientific method.
Analysis of living vertebrates shows that changes in brain evolution helped drive major shifts in reproduction across dinosaurs and birds. A bird egg can look surprisingly oversized for the body that produced it. That puzzle becomes even stranger when viewed through deep time: the largest known bird eggs exceed the largest eggs found from nonavian [...]
Gender ideology was defeated by sex ideology this week. But what both of these outlooks miss is what really makes us men and women, says Dr Sinéad Murphy – and how it protects us from the control of technocracy.
The iPhone X is a testament to device longevity, and durability. I gave mine to a family member when upgrading to an Xs Max in Late 2018, who held onto it all these years through a few different protective cases. Today I got it back where it’ll remain in my collection, after they upgraded to […]
This idea is so powerful—and so longed for—that it’s escaped containment among the Apple crowd. I’ve seen everything from Linux distro to phone updates referred to as Snow Leopard releases, when their vendors cite stability and bug fixes over new features. Likewise, people plead with their vendors for a Snow Leopard release when they feel quality has slipped.
People conflate a bunch of different ideas when talking about Snow Leopard:
Were there really zero no features? No, but there were fewer user-facing ones.
Was the initial release especially low in bugs? No, but it was better than Leopard’s.
Did it feel faster? Yes.
Was the final release especially low in bugs? Yes, it was fantastic.
Was it just because of the longer release cycle before Lion? No, they really did focus on quality for the initial release. And they didn’t add as much stuff mid-cycle as they did with Tiger and Leopard.
Snow Leopard’s stated goal internally was reducing bugs and increasing quality. That is a fact, not marketing. I am not sure why people on the internet don’t believe that, but I was there. If you wanted to ship a feature you had to get explicit approval from leadership and the bar was high. In normal feature releases it operated bottom up “here is what we are planning to ship” and in Snow Leopard it was top down “can we ship this?”.
AFAIK Snow Leopard was the first release of this kind (the first release I worked on was Jaguar or Puma), and was a direct response to taking 8 software updates to stabilize 10.5 and the severity of the bugs found during that cycle and the resulting bad press. Leopard was a HUGE feature release and with it came tons of (bad) bugs.
[…]
Testing was basically engineers, internal QA, some strategic partners like Adobe and MS, and the Apple Seed program (which was tiny). There was very little automated testing. Apple employees are not representative of the population and QA coverage is never very complete. And we sometimes held back features from seed releases when we were worried about leaks, so it wasn’t even the complete OS that was being tested.
Software updates are always needed, though the issues they fix became less severe over time due to larger seeds (aka betas), recovery partitions, and better / more modern development practices. But I can tell you FOR A FACT that Snow Leopard had fewer major bugs over its lifetime, coalesced very quickly, and was extremely solid when Lion was released.
I agree with you that Snow Leopard was billed as no USER VISIBLE features. But people did NOT just fix niggling bugs, it was an architecturally huge release. E.g., it introduced GCD. And unless I’m confusing the year, it rewrote the Mail backend to use it and mail hasn’t had reliable search since.
My memory is that quality was so low that we pushed back the release. With the extra time we did manage to fix enough bugs that it was well received. But internally it was more destabilizing than most releases due to the amount of architectural churn.
Yeah as someone else that worked on Snow Leopard I found this article and ones like it a bit silly. They’re a lot like the old “debug code” posts on Mac forums back in the day trying to explain why Puma was slow (no, you’ve got a G3 and an unaccelerated video card).
Tiger and Leopard were sprawling releases. Tiger covered 32-bit and 64-bit PowerPC, then 32-bit x86, then 64-bit x86 Macs. Tiger was also what I guess I’d say is the first “modern” OSX release, with subsystems like launchd and a more mature OpenDirectory replacing older NeXT subsystems.
Leopard in my experience was a train wreck. It shipped a lot of new features, both user facing and back end frameworks, but the development was seriously impacted from teams losing engineers to iOS. Leopard had features planned assuming 100% availability of SWE’s resources but ended up with 40-50% of SWE’s resources (made up numbers based on my feels at the time). Many new frameworks in Leopard did not land or get stable until very late in the development cycle which meant everything downstream had to scramble right before GM. It was 100% the case that Leopard was not really stable until 10.5.8 and still sucked IMHO.
There was a lot of clean-up needed in MacOS and that was Snow Leopard. It was not a perfect release but 10.6.3 (the second disc pressing IIRC) and onward were very stable. Dropping PowerPC support really helped focus QA since they didn’t need the massive array of test hardware Tiger and Leopard required. You also didn’t need to wrangle builds for four architectures, including multiple compilers as a few libraries (if not whole frameworks) were compiled with ICC on x86 for performance reasons.
The “Snow Leopard wasn’t that great” meme is weird. I’m sure it had its problems like every OSX release did. Unfortunately most OSX releases broke someone’s workflow. Snow Leopard ware no different. But it was always billed internally as a “no new features” release and those features that it did ship faced a very high bar to get in the release. I definitely look back on Snow Leopard as a high water mark for macOS quality in terms of a release.
If you weren’t there then you don’t know why I considered getting a “10.6.8” tattoo at one point. Boot Camp was no longer siloed, zero-drama Exchange support was baked in, Quicktime X hauled ass, and It was the definitive answer to the smoldering wreckage of Vista.
Snow Leopard has always remained the best Apple OS in my memory. For me Mail search was perfect all the time, once spotlight finished indexing it was incredible, iTunes, finder, everything just worked. The consistency was felt everywhere…
The silvery fur of the hamadryas baboon is, under a spectrometer, nearly the exact color of moonlight, which may explain why ancient Egyptians made a monkey the face of their moon god, according to a new study in Time and Mind.
The work, from biological anthropologist Nathaniel Dominy of Dartmouth College and primatologist Catherine Hobaiter of the University of St Andrews, takes an old Egyptological question and points an instrument at it. Thoth, god of the moon, writing, and magic, had two sacred animals: the ibis and the baboon. The ibis makes sense. A curved beak echoing a crescent, white plumage the same color as the moon’s glow.
The baboon, however, has long “defied explanation,” as one Egyptologist put it; the key problem being that baboons didn’t live in Egypt. Egypt’s pantheon features many local creatures, from the jackals that haunted its cemeteries to the cow that stood in for the mother goddess Hathor. But no wild baboon has ever been found in Holocene Egypt. The hundreds recovered from tombs and temples were all imports, carried in by ship from somewhere down the Red Sea coast. Of all the animal gods, the baboon is the only foreigner. “Why would two such different animals be used to represent one deity? Most other Egyptian deities are represented by just one type of animal. Ancient Egyptians were familiar with at least three species of ibis, but they chose the white one for embodying Thoth. They were also familiar with two species of baboon, along with vervet monkeys and patas monkeys, but again they chose the silver-white species,” explained lead author Professor Catherine Hobaiter in a press statement. According to the study, the Egyptians were picky. They knew two species of baboon and three of ibis, and each time they deified only one of each.
“Sacred ibises and hamadryas baboons are different in many ways, but one thing that unites them is their moon-like colour,” Hobaiter said.
To test whether color was the thread, the team recorded reflectance spectra from the hair of 12 baboon specimens at the American Museum of Natural History and lined them up against the measured spectrum of moonlight. The olive baboon came back green, peaking around 525 to 650 nanometers (which is precisely why it is called the olive baboon). The hamadryas came back silver-gray, roughly 65 percent brighter, with a curve the authors call “indistinguishable from moonlight.”
Spectroscopy results of baboon hair. Image: Catherine Hobaiter
According to the study and historical records, the living emblem of Thoth is not just the hamadryas but the mature male, with his heavy silver shoulder mantle and white cheek ruffs. This head of hair is so reflective the authors clock it as brighter than a golden lion tamarin, a monkey practically famous for glowing. The Germans noticed too. Their name for the animal is Silberpavian, the silver baboon.
There is a stranger layer beneath the color. Egyptians kept baboons in their temples partly to watch them, because the animals seemed to answer to the moon. There are historical records which indicate that male baboons in Egypt, during a fifth-century solar eclipse, fell into a state of “grief” and, according to the ancient writer, entered a sort of trance of reverence.
Modern ethologists watching zoo baboons during the2017 total eclipse logged something uncomfortably close: activity falling away, the animals going quiet and huddling together. The Egyptians, in effect, may have kept a small colony of living eclipse detectors and read their unease as devotion.
History being what it is, and not an exact science, the authors are careful not to pretend that their findings are direct evidence as to why Ancient Egyptians made gods of baboons. A spectrometer can confirm that a baboon is the color of moonlight. It cannot confirm that the color is why anyone bowed to it. The argument rests on a2024 etymology tracing Thoth’s name to a word meaning roughly “bright-thing.”
There is also an irony the study mostly steps around. The male’s silver mantle did not evolve to look like the moon; it evolved as a sexual signal, a way for dominant males to advertise themselves to other baboons. The Egyptians took a mating ornament and read it as a message from the sky.
That may be the most human thing in the whole account. The Egyptians were meticulous observers who noticed that one animal, in one sex, at one particular brightness, resembled the thing they worshiped, and decided the resemblance meant something.
One of those baboons even has a name. Harnufi was brought to Egypt in the sixth year of Ptolemy V and entombed 31 years later, on September 6, 168 BC. Someone counted out his life in years, mummified him, and laid him down as a small gray piece of the moon.
MJ Banias is a co-founder of The Debrief, covering science and technology news. You can email him at mj@thedebrief.org or follow him on LinkedIn.
Editor’s Note:Astrobites is a graduate-student-run organization that digests astrophysical literature for undergraduate students. As part of the partnership between the AAS and astrobites, we occasionally repost astrobites content here at AAS Nova. We hope you enjoy this post from astrobites; the original can be viewed at astrobites.org.
Look at an image of the sky taken with a sufficiently sensitive telescope, and you’ll quickly notice that galaxies tend to cluster into two main types: blue spiral galaxies, which have flat disk shapes with a central bulge, and red elliptical galaxies, which look like spherical or elliptical balls of red stars. Blue spiral galaxies can form tens to hundreds of stars every year, while elliptical galaxies have completely stopped forming stars, meaning that some process has to transform star-forming spirals into non-star-forming, or “quiescent,” elliptical galaxies. To form the current population of massive elliptical galaxies, this process had to be common about 2–3 billion years after the Big Bang at “cosmic noon,” the period when star formation in the universe peaked. The processes that “quench” star formation in massive galaxies are still being studied, and one of the best ways to study them is to find galaxies that recently quenched and look for clues about the processes that quenched them.
Post-starburst galaxies are galaxies that have rapidly quenched after a short burst of star formation. Because these galaxies quenched so quickly and so recently, it’s often possible to find signs of whatever quenched them, like the signatures of past galaxy mergers, feedback from supermassive black hole accretion, or the shutoff of gas flowing into the galaxy. Rapid quenching is pretty uncommon now, but it was a much more common way for galaxies to quench at cosmic noon. Understanding post-starburst galaxies at cosmic noon is therefore critical for understanding the formation of massive elliptical galaxies in the local universe.
The Quest for Quenched Galaxies
Today’s article uses data from the JWST Early eXtragalactic Continuum and Emission Line Survey (EXCELS) to identify post-starburst galaxies at cosmic noon and try to determine why they quenched. EXCELS is a spectroscopic survey, so the authors get a spectrum for every galaxy. The spectrum encodes information about the galaxy’s stellar population, including the mass of stars in the galaxy, the number of stars forming every year, and the history of star formation throughout the galaxy’s life.
The authors use a technique called principal component analysis to further divide the sample into young and old post-starbursts. Principal component analysis is a machine-learning technique that learns the most important features of a data set. This technique is used for “dimension reduction,” or reducing the number of data points needed to learn something about the object. A typical spectrum has hundreds or even thousands of data points, which means performing data analysis on a spectrum can be very computationally expensive. Principal component analysis takes these thousands of data points and learns broad patterns that correlate with each other. These patterns are called “supercolors” in the context of spectral data, and they encode things like the overall shape and color of the spectrum as well as the spectral shape around key features (see Figure 1 for a visualization). Since the overall shape, color, and emission/absorption line features of a spectrum come from the galaxy’s stellar population, this method can be used to identify galaxies with lots of star formation a billion years ago but very little star formation today — in other words, post-starburst galaxies.
Figure 1: An example of principal component analysis for sample star-forming (SF), quiescent (Qu), and post-starburst (PSB) galaxy spectra (left-hand side). Principal component analysis simplifies a many-dimensional data set (for example, spectra) into fewer dimensions. In this case, Super-Color 1 measures the overall color of the spectrum (shown on the left-hand side as the slope of the spectra, marked with red lines), while Super-Color 2 measures the shape of the spectrum around 4,000 angstroms (orange box). The authors use principal component analysis to identify post-starburst galaxies for further analysis (right-hand side). [Adapted from Skarbinski et al. 2026]
The authors apply principal component analysis to the galaxies in their sample and find that 11 of the galaxies in their sample are classified as post-starburst, 9 are quiescent, and 4 still have some star formation. To further analyze the stellar populations of the post-starbursts in their sample, the authors use a program called Bagpipes to fit the galaxies’ spectra. Bagpipes is a spectral energy distribution fitting software, which means that it takes the observed spectrum of a real galaxy and tries to match it to a library of different stellar spectra. By measuring the relative contribution of different kinds of stars (which all have different lifetimes), Bagpipes can compute the likely history of star formation in the galaxy (e.g., when the star formation rate peaked) as well as the present-day properties of the galaxy (things like the mass in stars versus dust and the current star formation rate). The authors use the galaxies’ star formation histories to try to find clues as to how they quenched.
How Quickly Do Post-Starbursts Quench?
First, the authors measure something called a “quenching timescale,” which they define as the length of time between when the galaxy’s star formation rate peaked and when it fell low enough that the galaxy was quenched. The quenching timescale depends on which process shut down star formation in the galaxy — feedback from black hole accretion or star formation should cause fast quenching, while galaxies that are starved of gas from the intergalactic medium should quench more slowly. The authors find that 15 of their galaxies quenched in under 500 million years, 6 took between 500 million and 1 billion years, and 3 took longer than 1 billion years to quench. The galaxies that had the highest peak star formation rates quenched the fastest, suggesting that feedback from star formation could have played a role in quenching these galaxies.
Figure 2: Possible evolutionary tracks in supercolor for two example galaxies as they quench. The galaxy in the top panel quenches quickly and has post-starburst supercolors for about a billion years, while the galaxy in the bottom panel quenches without ever going through the post-starburst phase. The authors use these tracks to determine how important the post-starburst phase is for quenching massive galaxies. [Skarbinski et al. 2026]
Next, the authors measure how important the post-starburst phase is to form massive quiescent galaxies. Not all galaxies that quench go through a post-starburst phase; some objects, especially those that quench slowly, will transition directly from star forming to quiescent. The authors use the star formation histories from their spectral energy distribution fits to predict how the galaxies’ supercolors changed after their star formation peaked (Figure 2) and find that six of the nine quiescent galaxies went through a post-starburst phase in the past, while the other three did not. For the objects that went through a post-starburst phase, the median time spent as a post-starburst was around 600 million years.The authors can use this measured “visibility timescale” to constrain whether the post-starburst phase is important for forming massive quiescent galaxies. If the fraction of post-starburst galaxies in a sample is high, that can be for two reasons: either a larger fraction of galaxies will eventually go through a post-starburst phase, or the post-starburst phase is very long, making it easy to find post-starburst galaxies. Using the measured timescale of 600 million years and combining with results from another article, the authors find that 40% of quiescent galaxies likely went through a post-starburst phase; for the more massive end of the sample, this fraction increases to around 73% due to the shorter visibility timescale. This suggests that the post-starburst phase is very important for forming the kind of massive quiescent galaxies we see in the local universe.
While the post-starburst phase is important, the different quenching timescales present across the sample suggest that multiple pathways existed to quench galaxies at cosmic noon, similar to what has been found in less-distant galaxies and at cosmic noon in othersamples. This is also supported by the fact that four of the five galaxies with sufficient data show evidence of an actively accreting supermassive black hole that may help shut down star formation in many (but perhaps not all) massive galaxies. While the precise processes that quench massive galaxies are still uncertain, one thing is clear: JWST EXCELS at solving the mystery!
Original astrobite edited by Anavi Uppal.
About the author, Margaret Verrico:
I am a fourth-year graduate student at the University of Illinois Urbana-Champaign. I study the connection between supermassive black hole transients and their host galaxies. I am also an avid knitter and reader, and I am passionate about opening up STEM opportunities for people of all backgrounds.
For 35 years, the Hubble Space Telescope has looked out into the Universe. Now, Lego is inviting builders to look inward with its latest model of the orbiting observatory.
The new Lego Icons Hubble Space Telescope (set no. 11382) was released on August 1 for $140 at the toy company's stores and its online shop. The 1,252-piece kit builds a 15-inch-long (38-cm) desktop model that is about twice as large as the previously released Lego Hubble models.
The Icons Hubble is the first to be sized in comparison to a Lego minifigure, such that the included astronaut provides a sense of scale for the telescope.