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Astronomers have observed three types of black holes in the Universe. Stellar-mass black holes formed from the collapse of a massive star, intermediate mass black holes found in some star clusters, and supermassive black holes that lurk in the centers of galaxies. But there is a fourth type that remains hypothetical an unobserved. Known as primordial black holes, they are thought to have formed from tiny fluctuations in the hot and dense early cosmos. Since they wouldn’t have formed from stars or mergers, they could have a much smaller mass. And with small masses, primordial black holes would be tiny. Their event horizons would be smaller than an apple, perhaps as small as a grain of sand. You can see why they would be hard to find.

If they exist, these dustmote singularities would be a perfect candidate for dark matter. This is not a new idea. Observations of dark matter have ruled out stellar-mass black holes and even planet-mass ones, but they haven’t quite ruled out primordial black holes. So they are a possible explanation for dark matter, but how would we prove it? A new study on the arXiv tries to find out.

Observational constraints on primordial black holes over various mass ranges. Credit: M. Cirelli (2016)

The authors begin by noting that if dark matter really is composed of primordial black holes, then they must be clustered around regular matter in the way dark matter does. There must be a halo of tiny black holes surrounding the Milky Way, and there must be primordial black holes scattered throughout our solar system. The gravitational pull of these tiny black holes should therefore affect the motion of planets, asteroids, and comets in detectable ways. Previous searches turned up nothing, but the authors wanted to know whether the effect would be significant enough to observe with our current technology.

So they ran several computer simulations to calculate the size of the effect. Since the gravitational pull of a single black hole would be tiny, the team looked at how nearby encounters would shift the orbits of solar system bodies. We describe orbital motion by ephemerides tables, so they used simulations to determine how the ephemerides would change over time. What they found was that even if we took a decade’s worth of ephemerides observations, the effect of primordial black holes would be an order of magnitude smaller than the limits of observation. In other words, even if primordial black holes exist their effect is way too tiny to observe in our solar system.

While the result is a bit disappointing, it does contradict a few studies that argue current observations rule out primordial black holes as dark matter. Though they are an unlikely solution to this cosmic mystery, they are still in the game.

Reference: Thoss, Valentin, and Andreas Burkert. “Primordial Black Holes in the Solar System.” arXiv preprint arXiv:2409.04518 (2024).

The post Could We Find Primordial Black Holes in the Solar System? appeared first on Universe Today.

Saturn is well known for its ring system and many recognise that the planets Jupiter, Uranus and Neptune also have rings. Did Earth ever have rings though? A team of researchers suggests that a worldwide collection of impact craters points to the existence of a ring around Earth millions of years ago. It’s possible that Earth captured and destroyed an asteroid that passed too close 466 million years ago. The asteroids torn up debris orbited the Earth as a ring and then the individual chunks entered the atmosphere, landed on the surface and produced the craters observed today. 

Seeing the rings of Saturn against an inky black sky are the very things that grabbed my attention as a ten year old boy. Since then I have been fascinated by all things space. The rings of Saturn, and Jupiter, Uranus and Neptune are made up of a collection of lumps of ice and rock all orbiting around the host planet in the same way our Moon orbits around the Earth. Collectively, and from a distance, they look like a complex system of rings. 

This NASA Hubble Space Telescope photo of Saturn reveals the planet’s cloud bands and a phenomenon called ring spokes. NASA, ESA, STScI, Amy Simon (NASA-GSFC)

The origin of the rings of the giant gas planets has been the cause of many debates over the decades. The most likely explanation is that the rings formed from the remains of moons or other celestial bodies that wondered a  little too close. The intense gravitational force from the planets tore the objects apart in a process known as tidal disruption. 

In a paper published by Andrew G. Tomkins and a team of researchers they suggest Earth too may have had its own rings in the past. Interactions between Earth and material from within our Solar System has been clearly evident. The Arizona crater and the Chicxulub impact event have left their scars on our planet but in the last 540 million years there was an increase in cratering events. Recorded in limestone deposits around the world are higher levels of chondrite (stony) meteorites and micrometeorite debris. At the same time there seems to have been an increase in seismic and tsunami activity although the correlation between the two is not confirmed. 

Barringer Crater, also known as Meteor Crater, in Arizona. This crater was formed around 50,000 years ago by the impact of a nickel-iron meteorite. Near the top of the image, the visitors center, complete with tour buses on the parking lot, provides a sense of scale. Credit: National Map Seamless Viewer/US Geological Service

The increase in meteoric material in limestone has been suggested as being caused by a general increase in asteroid dust across the inner Solar System but an interesting alternative theory has been suggested by Tomkins and his team. They propose instead that a large chondrite asteroid experienced a near-miss with Earth around 466 million years ago. If the object passed within the Roche limit of Earth, then Earth’s gravitational field will be strong enough to stop any smaller object from being held together by gravity. It would therefore break-up and lead to the formation of a debris ring.

The team investigated the impact sites of the 21 meteorite impacts known to coincide with the increase in meteorite activity in the Ordovician period. They then calculated the probability that the identified impact points resulted from randomly distributed impact events. This would be the likely cause of all the impactors came from the asteroid belt scenario. Instead the team concluded that the impact structure were located near to the equator as would be the case if they came from a single body that broke up in orbit. The resultant decay of the ring particles would have lasted several tens of millions of years before finally settling in the limestone records for future researchers to unearth. 

Source : Evidence suggesting that earth had a ring in the Ordovician

The post Earth Might Have Had Rings Half a Billion Years Ago appeared first on Universe Today.

In 2022, physicists were excited by hints that something was wrong with our understanding of the universe - but new results have put that in doubt

In my book, which I will now shamelessly promote – The Skeptics’ Guide to the Future – my coauthors and I discuss the incredible potential of information-based technologies. As we increasingly transition to digital technology, we can leverage the increasing power of computer hardware and software. This is not just increasing linearly, but geometrically. Further, there are technologies that make other technologies more information-based or digital, such as 3D printing. The physical world and the virtual world are merging.

With current technology this is perhaps most profound when it comes to genetics. The genetic code of life is essentially a digital technology. Efficient gene-editing tools, like CRISPR, give us increasing control over the genetic code. Arguably two of the most dramatic science and technology news stories over the last decade have been advances in gene editing and advances in artificial intelligence (AI). These two technologies also work well together – the genome is a large complex system of interacting information, and AI tools excel at dealing with large complex systems of interacting information. This is definitely a “you got chocolate in my peanut butter” situation.

A recent paper nicely illustrates the synergistic power of these two technologies – Interpreting cis-regulatory interactions from large-scale deep neural networks. Let’s break it down.

Cis-regulatory interactions refer to several regulatory functions of non-coding DNA. Coding DNA, which is contained within genes (genes contain both coding and non-coding elements) directly code for amino acids which are assembled into polypeptides and then folded into functional proteins. Remember the ATCG four letter base code, with three bases coding for a specific amino acid (or coding function, like a stop signal). This is coding DNA. Noncoding DAN regulates how coding DNA is transcribed into proteins.

There are, for example, promoter sequences, which are necessary for transcription in eukaryotes. There are also enhancer sequences which increase transcription, and silencer sequences which decrease transcription. Interactions among these various regulatory segments control how much of which proteins any particular cell will make, while responding dynamically to its metabolic and environmental needs. It is a horrifically complex system, as one might imagine.

CRISPR gives us the ability to not only change the coding sequence of a gene (or remote or splice in entire genes), it can also be used to alter regulation of gene expression. It can reversibly turn off, and then back on again, the transcription of a gene. But doing so messes with this complex systems of regulatory sequences, so the more we understand about it, the better. Also, we are discovering that there are genetic diseases that do not involve mutations of coding DNA but of regulatory DNA. So again, the more we understand about the regulatory system, the better we will be able to study and eventually treat diseases of gene expression regulation.

This is a perfect job for AI, and in this case specifically, deep neural networks (DNN). The problem with conventional research into a massive and complex system like the human genome (or any genome) is that the number of individual experiments you would need to do in order to address even a single question can be vast. You would need the resources of laboratory time, personnel and money to do thousands of individual experiments. Or – we could let AI do those experiments virtually, at a tiny fraction of the cost and time. This is exactly the tool that the researchers have developed. They write:

“Here we present cis-regulatory element model explanations (CREME), an in silico perturbation toolkit that interprets the rules of gene regulation learned by a genomic DNN. Applying CREME to Enformer, a state-of-the-art DNN, we identify cis-regulatory elements that enhance or silence gene expression and characterize their complex interactions.”

Essentially this is a two-step process. Enformer is a DNN that plows through tons of data to learn the rules of gene regulation. The problem with some of these AIs, however, is that they spit out answers but not necessarily the steps that led to the answers. This is the so-called “black box” problem of some AIs. But genetics researchers want to know the steps – they want to know the individual regulatory elements that Enformer identified as the building blocks for the overall rules the produce. That is what CREME does – it looks at the rule output of Enformer and reverse engineers the cis-regulatory elements.

The combination essentially allows genetics researchers to run thousands of virtual experiments in silico to build a picture of cis-regulatory elements and interactions that make up the web of rules that control gene expression. This is great example of how AI can potentially dramatically increase the pace of scientific research. It also highlights how genetics is perhaps ideally suited to reap the benefits of AI-enhanced research, because it is already an inherently digital science.

This is perhaps the sweat spot for AI-enhanced scientific research – look through billions of potential targets and tell me which 2 or 3 I should focus on. This also applies to drug research and material science, where the number of permutations – the potential space – of possible solutions is incredibly vast. For many types of research, AI is condensing down months or years of research into hours or days of processing time.

For genetics these two technologies (AI and gene-editing such as, but not limited to, CRISPR) combine to give us incredible knowledge and control over the literal code of life. It still takes a lot of time to translate this into specific practical applications, but they are coming. We already, for example, have approved therapies for genetic diseases, like sickle cell, that previously had no treatments that could alter their course. More is coming.

This field is getting so powerful, in fact, that we are discussing the ethics of potential applications. I understand why people might be a little freaked out at the prospect of tinkering with life at its most fundamental level. We need a regulatory framework that allows us to reap the immense benefits without unleashing unintended consequences, which can be similarly immense. For now this largely means that we don’t mess with the germ line, and that anything a company wishes to put out into the world has to be individually approved. But like many technologies, as both AI and genetic manipulation gets cheaper, easier, and more powerful, the challenge will be maintaining effective regulation as the tech proliferates.

For now, at least, we can remain focused on ethical biomedical research. I expect in the next 5-20 years we will see not only increasing knowledge of genetics, but specific medical applications. There is still a lot of low hanging fruit to be picked.

The post The Potential of AI + CRISPR first appeared on NeuroLogica Blog.

A ring of asteroid debris could have orbited Earth for tens of millions of years, and perhaps even have altered the planet's climate

The Moon has inspired poets and artists, musicians and playwrights. The sight of our one and only Moon is familiar to anyone that has ever glanced up at the night time (and sometimes day time sky!) Every so often though, our Moon (note the use of capital ‘M’)is joined by a small asteroid that wanders too close. Astronomers have detected an 11-metre wide asteroid that has the snappy name 2024 PT5 and it came within 567,000 kilometres of Earth and will become a temporary satellite from 29 September until 25 November when it will leave our system. 

Planets, comets, satellites and asteroids are the main constituents of our Solar System, plus of course, the Sun. The asteroids are small rocky objects that orbit the Sun with the majority in orbits between Mars and Jupiter. These remnants of the early Solar System come in a wide range of sizes from those measuring just a few centimetres to others measuring hundreds of kilometres. They have no atmosphere and are usually irregular in shape. 

The asteroid Dimorphos was captured by NASA’s DART mission just two seconds before the spacecraft struck its surface on Sept. 26, 2022. Observations of the asteroid before and after impact suggest it is a loosely packed “rubble pile” object. Credit: NASA/JHUAPL

Asteroids that pass within 1.3 astronomical units (one astronomical unit is the average distance between the Sun and Earth) are typically referred to as near-earth objects (NEOs.) Their proximity to Earth means they may – if not immediately – pose a potential impact threat to Earth. Most NEO’s pass by harmlessly on each orbit but they are tracked for future threats. The study of this family of asteroids helps us to understand about the formation of the Solar System. 

On occasions, Earth can capture asteroids from the NEO group and for a short period, pull them into an orbit. These temporary captures can be very short lived not even lasting for an entire orbit before returning to their regular trajectory.  Others like 2006RH120 remained in orbit around Earth for a year, while some have been captured for more than a year. These mini-moon events have even turned out to be pieces of space junk like one identified in 2020 which turned out to be a rocket booster from the launch of Surveyor 2 in 1966!

This 1964 photograph shows a Centaur upper-stage rocket before being mated to an Atlas booster. A similar Centaur was used during the launch of Surveyor 2 two years later. Credit: NASA

Asteroid 2024 PT5 is a NEO that was discovered on 7 August 2024 by ATLAS, the Asteroid Terrestrial-impact Last Alert System. It measures 11 metres across and can approach within 1 million kilometres of Earth in an orbit whose path resembles a horseshoe shape. This complex type of orbit occurs when a smaller object orbits a relatively larger object. In the case of 2024 PT5, the gravitational attraction of Earth changes the shape of the asteroids elliptical orbit. The horseshoe shape is only evident when the orbit of the asteroid is mapped relative to both the Sun and the Earth.

The dynamics of the two objects means that for a period of 56 days from 29 September to 25 November, 2024 PT5 will officially orbit the Earth although it is only classed as a ‘temporary captured flyby.’ It will only perform one single orbit however before it returns to its usual heliocentric, Sun centred orbit. This won’t be the only time though as it is predicted to return again in 2055. 

Don’t get too excited about seeing it though. The object will be far too faint to be seen with the naked eye, even beyond the visual range of amateur telescopes. It is however possible for experienced amateur astronomers to capture images of the asteroid using astronomical imaging techniques.

Source : A Two-month Mini-moon: 2024 PT5 Captured by Earth from September to November

The post Earth Will Have a Tiny New Mini-Moon for a Few Months appeared first on Universe Today.

15 popular myths about sleeping, debunked.

AI reviews the medical literature on the mechanisms of various SCAMs

The post AI and the SCAM Literature first appeared on Science-Based Medicine.

The number of people worldwide directly killed by antibiotic resistance will rise to 1.9 million a year by 2050, according to the most comprehensive study so far

When the James Webb Space Telescope was launched on Christmas Day in 2021, it faced a whole host of intriguing questions. By the time it finally launched, astronomers had a big list of targets begging for the type of detailed observations that only the powerful infrared space telescope could perform. One of the targets was an ancient, massive galaxy that’s basically dead and forms no new stars.

The results are in, and an international team of astronomers know what happened to the quiescent galaxy.

The growth and evolution of galaxies is a key field of study in astronomy. How did we get from the Big Bang to today, when massive galaxies like our own Milky Way populate the Universe? Astronomers have learned that supermassive black holes (SMBHs) reside at the heart of massive galaxies and have shaped their galaxies in powerful ways.

SMBHs create powerful active galactic nuclei (AGN) in galaxies’ cores. As an SMBH draws material toward it, the material collects in an accretion disk. The material is heated to extremely high temperatures and gives off energy across the electromagnetic spectrum, creating an AGN that can outshine the rest of the galaxy.

AGN are powerful objects. According to theory, they have the power to disrupt the supply of cold star-forming gas and to dramatically slow the star formation rate (SFR) in their host galaxy. They blow winds of star-forming gas out of their galaxies, which slows the SFR. Astronomers call this quenching, and it’s frequently observed in massive galaxies called quiescent galaxies.

Now, the JWST has observed an ancient massive galaxy named GS-10578 at redshift z?=?3.064. It’s nicknamed ‘Pablo’s Galaxy,’ and for such an early stage in the Universe’s evolution, it’s massive: it holds about two billion solar masses. But Pablo’s Galaxy is quenched, meaning most of its star formation happened between 12.5 and 11.5 billion years ago. Many local massive galaxies are quenched, which helped propel the development of the theory of AGN quenching.

A team of scientists has presented their research into Pablo’s Galaxy in a new paper titled “A fast-rotator post-starburst galaxy quenched by supermassive black-hole feedback at z?=?3.” The paper is published in Nature Astronomy, and the co-lead author is Francesco D’Eugenio from the Kavli Institute for Cosmology and the Cavendish Laboratory at the University of Cambridge in the UK.

“We found the culprit. The black hole is killing this galaxy and keeping it dormant, by cutting off the source of ‘food’ the galaxy needs to form new stars.”

Francesco D’Eugenio, Kavli Institute for Cosmology, University of Cambridge, UK

“Local, massive, quiescent galaxies stand like colossal wrecks of glorious but remote star-formation histories (SFHs) and mighty and rapid quenching, the likes of which have no present-day equals,” the authors write. “The James Webb Space Telescope (JWST) has enabled us for the first time to witness these monumental galaxies during the long-gone epoch when they arose and fell.”

“Based on earlier observations, we knew this galaxy was in a quenched state: it’s not forming many stars given its size, and we expect there is a link between the black hole and the end of star formation,” said co-lead author Dr Francesco D’Eugenio from Cambridge’s Kavli Institute for Cosmology. “However, until Webb, we haven’t been able to study this galaxy in enough detail to confirm that link, and we haven’t known whether this quenched state is temporary or permanent.”

“In the early universe, most galaxies are forming lots of stars, so it’s interesting to see such a massive dead galaxy at this period in time,” said co-author Professor Roberto Maiolino, also from the Kavli Institute for Cosmology. “If it had enough time to get to this massive size, whatever process that stopped star formation likely happened relatively quickly.”

Pablo’s Galaxy is sometimes called a ‘blue nugget,’ a class of galaxies thought to exist only in the early Universe. Blue nuggets are massive and extremely compact, and astronomers think they’re precursors to modern quiescent galaxies called ‘red nuggets.’ Blue nuggets are experiencing ‘gas-rich compaction.’ That means that there’s a central burst of star formation that’s driven by disk instability or gas-rich major mergers. That burst is followed by quenching, which leaves a red nugget galaxy.

Artist’s illustration of a “red nugget” galaxy. Credits: X-ray: NASA/CXC/MTA-Eötvös University/N. Werner et al., Illustration: NASA/CXC/M. Weiss

“As we will show, GS-10578 is, instead, already a red nugget in an advanced stage of quenching,” the authors write. They explain that it’s merging with several low-mass satellite galaxies and “is undergoing powerful, ejective feedback from its SMBH.”

The researchers say they’ve direct evidence that AGN feedback can quench star formation in early galaxies. Previous observations with other telescopes show that galaxies have fast outflowing winds of gas. That gas is hot, making it easier to see, but it didn’t provide evidence that SMBHs and AGN can quench star formation. That’s because the gas is hot, and stars form from cold, dense gas.

Pablo’s Galaxy is no different. It’s expelling large quantities of hot gas at velocities high enough to escape the galaxy completely. The SMBH and its AGN are pushing the gas out.

But the JWST made the difference in these new observations. It observed a new component of the outflowing wind made of cold gas. The cold gas doesn’t emit light, but the JWST is extremely sensitive and can detect it by the way it blocks out light from distant galaxies in the background. Critically, without cold gas, a galaxy struggles to form stars and becomes quenched.

This figure illustrates some of the research findings. It shows Pablo’s Galaxy in the middle, with five low-mass satellite galaxies merging. The inset (b) shows detail from the main image. The cyan outline is offset to the northwest and represents the outflow of cold gas that is quenching star formation in the galaxy. Image Credit: D’Eugenio and Maiolino et al. 2024.

The amount of gas being expelled by the AGN-driven winds is greater than the amount needed to form new stars.

“We found the culprit,” said D’Eugenio. “The black hole is killing this galaxy and keeping it dormant, by cutting off the source of ‘food’ the galaxy needs to form new stars.”

These are exciting results, but the authors caution that this is just one galaxy. “GS-10578 represents a unique opportunity to study how the most massive galaxies in the Universe became—and stayed—quiescent,” the authors explain in their research. “Even though we cannot draw general conclusions from a single target, we show that AGN feedback is capable of powering neutral-gas outflows with high velocity and high mass loading, sufficient to interrupt star formation by removing its cold-gas fuel.”

There are also still outstanding questions. Other galaxies similar to Pablo’s Galaxy also show that outflow winds of cold gas could be key to galaxies’ quenching. “How exactly these outflows are coupled with the AGN is not yet clear,” the authors write. They explain that only a census of similar galaxies can tell us whether these strong ejections of star-forming gas are a key mechanism for causing quenching or if the ejection of gas is merely episodic.

The JWST also answered another outstanding question about quenched galaxies. Our theoretical models showed that when a galaxy’s star formation was quenched, it was a turbulent event that violently destroyed the galaxy’s shape. Pablo’s Galaxy still displays the stately disk-shape of an untroubled galaxy. Its stars are moving in a uniform, predictable way.

This figure from the study shows the Pablo Galaxy’s orderly rotation. The observed velocity difference is because one side is moving away from us and is red-shifted from our perspective, while the other is moving toward us and is blue-shifted. Image Credit: D’Eugenio and Maiolino et al. 2024.

The JWST is working exactly as intended. By bringing the ancient Universe into view, it’s answering many longstanding questions in astronomy, astrophysics, and cosmology.

“We knew that black holes have a massive impact on galaxies, and perhaps it’s common that they stop star formation, but until Webb, we weren’t able to directly confirm this,” said Maiolino. “It’s yet another way that Webb is such a giant leap forward in terms of our ability to study the early universe and how it evolved.”

The post A Black Hole has Almost Halted Star Formation in its Galaxy appeared first on Universe Today.

Archaeologists are using AI and US spy satellite imagery from the cold war to find ancient underground aqueducts that helped humans survive in the desert

When I walk home in the afternoon these days, I always have a bag of walnuts or unsalted peanuts with me.  There are an unpredictable number of squirrels on my route home, and now that the Quad is open (it has been fenced off all summer for paving of the walks), squirrels are starting to appear in single-digit numbers, and they look SKINNY.

Also, after a tough day, there is nothing to cheer one up more than giving a nut to a hungry squirrel.

At any rate, I fed a couple on my way across the quad today (1 nut each), but then encountered a hungry little fellow (or girl) near the Presidential House. I gave it a peanut, and it grabbed it up immediately. But instead of eating the nut, the rodent sat there on its haunches about ten feet away from me with the nut in its mouth, staring at me. It was as if he wanted another nut.

I was a bit reluctant to proffer another peanut because, unlike chipmunks, squirrels lack cheek pouches, and where would he put it? But I tossed him another nut. He grabbed that one up, too, and then he had two peanuts sticking out of his mouth.  I thought he’d eat one of them, but how could he? If he tried, he’d drop one of the nuts.

Eventually Mr. (or Ms.) Squirrel ran up a tree and sat on a low branch, still staring at me. Both nuts were hanging out of his mouth like fangs. I don’t know what happened in the end, but as I left, he was still sitting on the branch and staring at me with two nuts in his mouth:

 

Imagine simply telling your vehicle, 'I'm in a hurry,' and it automatically takes you on the most efficient route to where you need to be. Engineers found that an autonomous vehicle (AV) can do this with the help of ChatGPT or other chatbots made possible by artificial intelligence algorithms called large language models.

Imagine simply telling your vehicle, 'I'm in a hurry,' and it automatically takes you on the most efficient route to where you need to be. Engineers found that an autonomous vehicle (AV) can do this with the help of ChatGPT or other chatbots made possible by artificial intelligence algorithms called large language models.

Researchers harnessed the power of sunlight to transform two of the most harmful greenhouse gases into valuable chemicals. The discovery could help combat climate change and provide a more sustainable way to produce certain industrial products.

Researchers used robotics and additive manufacturing to toughen cement-based material with precisely placed hollow tubes. The result is more than 5 times tougher than counterparts.

Researchers developed RAPTOR, a patent-pending optical counterfeit detection method for chips used in semiconductor devices. It leverages deep learning to identify tampering. It improves upon traditional methods, which face challenges in scalability and discriminating between natural degradation and adversarial tampering.

You're a hotshot working to contain a wildfire. The conflagration jumps the fire line, forcing your crew to flee using pre-determined escape routes. At the start of the day, the crew boss estimated how long it should take to get to the safety zone. With the flames at your back, you check your watch and hope they were right. Firefighters, disaster responders, rural health care workers and professionals in myriad other fields need a tool that incorporates all aspects of a landscape's structure to estimate travel times.

Renewable energy sources like wind and solar are critical to sustaining our planet, but they come with a big challenge: they don't always generate power when it's needed. To make the most of them, we need efficient and affordable ways to store the energy they produce, so we have power even when the wind isn't blowing or the sun isn't shining.

An experiment tested six generative large language models against students in an online introductory biomedical and health informatics course. The models scored higher than as many as three quarters of the real-world students in the class.