A genomic study of Greenland sharks, thought to be the longest-lived vertebrates on the planet, is hinting at the secrets to their epic lifespan and cancer resistance.

Earth has many unique features for a planet, such as a magnetic field, a large moon, and plate tectonics. It’s also the only planet we know of that harbors life. These facts form the basis of the Rare Earth hypothesis, which posits that we haven’t found aliens because other planets in the Galaxy probably don’t have all the right conditions for life. 

Another characteristic of Earth is that about 30% of its surface is land and about 70% is ocean. Recently, Columbia University Assistant Professor David Kipping investigated whether the proportion of Earth’s surface covered by dry land versus ocean, or its land fraction, is another reason Earth is habitable not only for simple single-celled organisms, but also for intelligent species like humans. 

To test this hypothesis, Kipping created 4 statistical models of planets with different land fractions that intelligent aliens could potentially evolve on. First, he created an equation to describe the likelihood that a planet in its star’s habitable zone has a particular land fraction, known as a probability distribution. Kipping weighted this probability distribution toward the extreme ends, making it more likely that a planet would be covered by a single huge landmass or a single vast ocean than by a mix of both, as on Earth. 

Kipping then incorporated this land fraction probability distribution into his statistical models to calculate the probability that a random planet will have that land fraction and host intelligent life. The 4 scenarios Kipping tested were: 1) that intelligent life is more likely to emerge on land-dominated planets, 2) that it’s more likely to emerge on ocean-dominated planets, 3) that it’s more likely to emerge on planets with roughly equal amounts of land and ocean, and 4) that its emergence is independent of a planet’s land fraction. 

As a first step in determining the kinds of planets intelligent aliens would tend to emerge on, Kipping used each model to predict the probability that intelligent life would emerge on a planet with the same land fraction as Earth. He then compared these probabilities by calculating the ratios between each value. Because Earth is the only known planet with intelligent life, a model that predicted a greater probability for humanity’s existence on Earth would be more likely to reflect reality.

Kipping considered it strong evidence that a given model was more realistic than another if the ratio between 2 of them was greater than 10, meaning one model was 10 times more likely to predict the existence of Earth and humanity. Kipping found that no comparison of any 2 models passed this threshold. However, the models assuming that intelligent life prefers ocean-dominated planets or planets with a land-ocean balance were 2.5 and 3 times more likely to predict the existence of humanity than the model assuming that intelligent life prefers land-dominated planets. Additionally, the model assuming that intelligent life prefers a land-ocean balance was always more likely to predict humanity than any other model, though marginally. 

Kipping also addressed whether finding more planets with intelligent life would affect which model was deemed most realistic, for example, if scientists discovered conclusive evidence of life on Mars in its distant past. Here, Kipping identified 2 complications. First, it’s uncertain how much of Mars’s surface was once covered by water – some estimate it had a land fraction as high as 81%, while others estimate it was as low as 25%. Second, proving that Mars once had life would not prove it once had intelligent life.

Regardless, Kipping reran the models assuming that ancient Mars had a land fraction comparable to Earth’s. Adding this second data point produced ratios similar to those in the earlier Earth-only calculations, meaning it still didn’t make any single model 10 times more likely to predict the existence of humans and Martians, respectively. 

Kipping then took the 10-times threshold and reversed the calculations to find what conditions would exceed it. In doing so, he calculated that astronomers would need to find 14 other planets with intelligent life and known land fractions to robustly determine whether intelligent life is more likely to occur on desert planets, ocean planets, balanced planets, or without bias.

Kipping concluded that he can’t yet definitively state whether there is something special about Earth’s land fraction when it comes to producing intelligent species. However, Earth’s existence would suggest that intelligent life is unlikely to favor extreme desert planets, so the Milky Way probably isn’t filled with Tatooines and Jakkus. And while his analysis doesn’t debunk the Rare Earth hypothesis, it does undermine the argument that Earth’s ocean size explains why Earth is rare. 

The post Is Earth’s water why intelligent life evolved here? appeared first on Sciworthy.

Scientists have developed “living plastics” that can be programmed to break themselves down when triggered. Many plastic items are made for one-time use, but the materials can remain in the environment for years. Researchers are exploring a different approach: living plastics, materials built with microbes that can be activated to break down the polymer when [...]

Clinical trials in China are getting attention at an international oncology gathering in Chicago. China’s surging biotechnology industry is fueling alarm that U.S. dominance in the field is waning.

In the book "Bitter Honey," writer and researcher Jennie Durant explores how industrial agriculture is destroying bees — and what can be done to stop them.

The babies were part of a vaccine trial for a respiratory virus in the 1960s and died shortly after. Their families said they had been unaware of the trial until recently.

Scientists have long known that migrating birds and homing pigeons navigate in part by sensing the Earth's magnetic fields, especially at night or in overcast conditions when visual landmarks or sunshine are in short supply. But exactly where this magneto-sensing occurs in the body—and the mechanism that enables it—remains a matter of intense debate. A new paper published in the journal Science suggests that homing pigeons have iron-rich immune cells in their livers that help them detect magnetic fields and transmit that information to the brain.

There are three primary hypotheses for how birds might sense Earth's geomagnetic field. One is a compass-like mechanism, whereby the Earth exerts a pull on magnetic particles in a bird's upper beak that relays directional information via a large nerve in the cranium. A second is that it happens biologically via cellular ion channels sensitive to voltage, enabling birds to sense changes in the magnetic field. And a third suggests that physical effects on retinal pigments enable birds to detect photons and send signals to the brain, although this mechanism is really only viable in the light.

None fully explain how animals can sense magnetic fields. However, “We had some clues that the liver and spleen have magnetic properties, because they break down red blood cells and so store much iron in the body,” said co-author Clivia Lisowski of the University of Bonn and the University Hospital Bonn. This refers to a 2015 paper suggesting that red pulp macrophages in the spleens of mice and humans are intrinsically superparamagnetic and hence more sensitive to magnetic fields. But it wasn't clear if those properties were involved in any kind of magnetoreception.

Read full article

Comments

© Christian Ziegler/ Max Planck Institute of Animal Behavior

How animals navigate by Earth's magnetic field is hotly debated. New research in pigeons points to iron-laden liver immune cells as the compass.

The billionaire’s new roots in Argentina are said to be partly motivated by concerns about the future of the United States and shared beliefs with Argentina’s right-wing leader.

Pope Leo XIV’s spiritual message on artificial intelligence arrived as Silicon Valley’s A.I. enthusiasts pursue their own spirituality through technology.

Hours of diving videos and hundreds of survey responses reveal the common diver mistakes that can cause irreversible reef damage.

It takes a village to deliver a whale calf. That’s what the most detailed video ever of a sperm whale birth shows.

In the footage, a female whale in labor is surrounded by others assisting her. Almost all of her helpers are female. But not all are related to the birthing mom. This shows that sperm whales benefit from cooperation, just as humans do.

Because getting to watch the birth of a whale is extremely rare, only a few scientific studies have described them. Some of those reports have noted other whales helping the mom through the birthing process. But scientists had never caught this on video.

In 2023, David Gruber was part of a team that got very lucky. Gruber is a marine biologist. He works with Project CETI, a nonprofit dedicated to sperm whale research. Project CETI is partly based on the island of Dominica in the Caribbean Sea. Gruber was in a boat right off the coast when his team caught the birth.

The researchers weren’t looking for a whale birth. They just happened to be in the right place, at the right time — with the right equipment. Using two drones, the team caught the whole 34-minute birthing process on tape.

A group of 10 whales surrounded the laboring mom. After the birth, her assistants took turns lifting the newborn to the surface for hours. This allowed the calf to breathe air until it could swim on its own.

The whales seemed to include the scientists in this event, Gruber says. “They literally carried the baby right past the front of our boat.” His group shared its video in Science on March 26.

Helping hands — or fins

Project CETI has been studying sperm whales around Dominica for long enough that Gruber and his colleagues could identify every individual in the video. “Not only did we capture such an amazing dataset, but we actually knew each of these whales,” he says.

Computers tracked each whale’s position in the footage. Then, a team member labeled each animal. A whale named Rounder was giving birth, the researchers determined. They also figured out what each of the other 10 whales did and how they were related to the mom. 

Rounder’s helpers included whales from two different female lines. These are like whale families, also called kin groups. The kin groups’ teamwork was surprising, because these groups don’t usually spend time together searching for food. But whales from the two groups fully mixed for hours after the birth. All helped lift the newborn calf at some point.

The four whales that helped hold the calf the most were its mother, aunt, an older kin member and one whale from outside the calf’s kin group. Holding the baby up is very important, because it can’t float on its own yet. Without help, Gruber says, “it would have sunk.”

Killer whales, belugas and other cetaceans have also been seen pushing newborns to the surface. This behavior may go back to when those species shared a common ancestor, Gruber says.

The wails of labor

Along with the video, the researchers also recorded audio of the birth. They analyzed these sounds with help from some other researchers. 

Sperm whales make sounds called codas. The scientists looked for changes in things like the codas’ rhythm. Those codas changed during important moments in the birth. One specific coda was heard more frequently during the birth. The team reported its findings March 26 in Scientific Reports.

Different sounds being linked with the birth is not surprising, says Denise Herzing. She’s a marine biologist who heads the Wild Dolphin Project. Based in Jupiter, Fla., this nonprofit focuses on Atlantic spotted dolphins.

“Marine mammals, in general, have specific sounds during specific behavioral contexts,” says Herzing.

After the birth, the sperm whales also ran into several pilot whales. Now, the sperm whales’ vocal style changed more. That might be because pilot whales sometimes bother sperm whales.

It takes a village

Giving birth is one of the most critical moments of a female whale’s life. Such high stakes might have driven these mammals to evolve cooperative instincts, the researchers say.

This is spot on, Herzing says. “We see different alliances of dolphins grouping into bigger groups to fight off a predator or to mate.”

Sharing the birth with the world took cooperation from the human team, too. Many scientists had to work together to film the video, analyze it and map the relationships between the whales. “It was a very profound experience for all of us,” says Gruber.

Kinematics: The Velocity-Time Function Author’s Preface: A Collaborative Approach to Lesson Development The intention behind what I hope will be a series of articles on Kinematics (this one being the first) is to begin an open, collaborative process of lesson development on Physics Forums. In order to expedite this workflow, I am making deliberate use...

It helped to have a number of features to aid survival following the end-Cretaceous mass extinction.

The administration is delaying a phaseout of hydrofluorocarbons, potent planet-warming chemicals used in air-conditioning and refrigeration.

© Gene J. Puskar/Associated Press

Most people think of Mars as a big red dustball, but researchers recently found Martian mineral deposits suggesting it was once warm and humid. The team used the Compact Reconnaissance Imaging Spectrometer aboard NASA’s Mars Reconnaissance Orbiter to analyze specific wavelengths of visible and near-infrared light from minerals on Mars’s surface to determine their chemical composition from afar.

Past researchers identified layered silicate minerals, called clays, across the Martian surface. Clays form when water interacts with rock, and record the amounts and chemical compositions of the waters that formed them. As water interacted with Martian surface rocks, it picked up more mobile elements like magnesium and iron and carried them to lower depths in the Martian soils, while less mobile elements like aluminum stayed in place. This process, called leaching, created 2 distinct layers of clays in the Martian rocks. 

Scientists have proposed 2 main hypotheses for how these layered clays formed on Mars. The first is that they formed through underwater leaching in pools or lakes sometime in Mars’ past. The second is that they formed across the Martian surface, where a widespread humid environment provided the moisture needed to leach them. 

To evaluate these hypotheses, a team led by researchers at Purdue University recently estimated the “true” thicknesses of Martian clay layers with a method scientists had previously only used on Earth. Rock layers containing clays can become tilted, making them appear thicker or thinner than they actually are. To address this discrepancy, the team used the High Resolution Imaging Science Experiment (HiRISE) tool on the Mars Reconnaissance Orbiter to create high-resolution elevation maps of the Martian surface. Then they combined these maps with surface composition data from the Compact Reconnaissance Imaging Spectrometer to create 3D composition maps. 

Using the 3D composition maps, the researchers found where each clay layer was exposed at the surface and traced it underground to estimate an angle of tilt. They then used trigonometry to calculate the true thicknesses of each clay layer. They analysed 46 regions across the Martian surface, and found that the combined thickness of both clay layers was around 20 to 680 feet (6 to 200 meters), with an average of about 190 feet (60 meters). That’s a maximum thickness as high as a 60-story building! 

Next, the researchers tested the extent of the clay deposits in a large ancient Martian valley known as the Mawrth Vallis Region. They focused on this region because it had large elevation changes, and scientists in the past had already collected high-resolution chemical composition and elevation data there. 

They explained that if the clay layers were restricted to the lowest parts of the valley where water once existed, and had changing thicknesses and boundaries between layers, this would provide strong evidence in favor of the “underwater leaching” hypothesis. In contrast, if the clay layers were more widespread, with consistent layer boundaries and thicknesses, this would provide strong evidence of a humid surface environment, in favor of the “surface leaching” hypothesis. 

The researchers found that the clay layers extended beyond the lowest parts of the valley and had consistent layer boundaries across more than half a mile (about a kilometer) of elevation change. Thus, they concluded that the clay layers formed by surface leaching in a humid environment. 

These findings conflict with climate models of early Mars, which generally suggest that the Martian surface rarely got above freezing temperatures. To address this discrepancy, the team proposed that these deposits could have formed over a long period of time rather than in a consistently warm and wet environment. If the surface was frozen most of the time, but got above freezing in short bursts, these clay deposits could still have formed, just over a much longer time period. In this case, the Mars climate models and the researchers’ findings would agree.

The researchers acknowledged that their study has some limitations, particularly regarding the sparse sample locations. Though they found strong evidence for a widespread humid environment on early Mars, more in-depth studies of locations like Mawrth Vallis could better constrain the specific surface environmental conditions under which these clays formed and potentially reconcile their data with Martian climate models.

The post Clay minerals suggest a warm, wet past for Mars appeared first on Sciworthy.

Security researcher Brian Krebs brings us the news that America's Cybersecurity & Infrastructure Agency (CISA) has had a large store of plaintext passwords, SSH private keys, tokens, and "other sensitive CISA assets" exposed in a public GitHub repo since at least November 2025.

The now-offline public repo—named, somewhat aspirationally, "Private-CISA"—was brought to Krebs' attention by GitGuardian's Guillaume Valadon, who was alerted to the repo's presence by GitGuardian's public code scans. Krebs says that Valadon approached him after receiving no responses from the Private-CISA repo's owner.

In an email to Krebs, Valadon claimed that the repo's commit logs show that GitHub's default protections against committing secrets—protections designed to protect unwitting or unskilled developers against exactly this kind of stupidness—had been disabled by the repo's administrator.

Read full article

Comments

© Dzmitry Skazau / Getty

Stars are mostly made of 2 elements: hydrogen and helium. While this has always been the case, those 2 elements and lithium were the only elements in existence when the Big Bang occurred around 14 billion years ago. When the first stars exploded, they released those primordial elements, as well as heavier elements produced by nuclear fusion inside them. 

Astronomers call all elements heavier than hydrogen and helium metals, a term chemists use quite differently. Subsequent generations of stars, including the Sun, formed in clouds of gas and dust enriched with these metals, such as carbon, oxygen, magnesium, and silicon. Scientists estimate that modern stars are 1% to 5% metal by mass.

Astronomers claim there is no solid evidence that stars contain exceptionally high amounts of metals, but some, called chemically peculiar stars, appear to. Astronomers study stars by looking at the patterns of light they emit, called spectra. Each element produces a unique light pattern, so astronomers can compare the light patterns in a star’s spectra to determine how much of each element is present, especially in the outer layers of the star. Researchers theorize that chemically peculiar stars don’t actually have more metals than average stars. Instead, they think that metals from their interiors diffuse to their outer layers more than in most stars.

A team of researchers from the American Association of Variable Star Observers and Masaryk University in Czechia recently observed 85 chemically peculiar stars to understand their behavior and better classify them. For their study, they first used the General Catalog of CP Stars, published in 2009 in Astronomy & Astrophysics, to identify targets across the 4 classes of these stars, labeled CP1 through CP4. CP1 stars have strong spectral patterns for iron and other heavy elements, CP2 stars have strong patterns for silicon, chromium, strontium, and europium, CP3 stars have strong patterns for mercury and manganese, and CP4 stars have either unusually weak or usually strong helium patterns. 

The team compiled a list of 85 stars to observe, then used the BRIght Target Explorer (BRITE) Constellation to monitor changes in their brightness. The BRITE Constellation is a set of 5 satellites equipped with telescopes and cameras for either red or blue light. Using the BRITE Constellation, the team monitored each star for several days. 

They found that 74 of these 85 chemically peculiar stars varied in brightness during their survey. They attributed this to the varied abundance of metals on their surfaces, which would form dark patches that go in and out of view from Earth’s perspective as the stars rotate. The team observed that 6 of these 74 stars appeared to change in brightness over multiple periods. They were surprised by this result because a star’s brightness wouldn’t vary over multiple periods if the changes were due to rotation. They compared their findings to data other scientists had collected from these stars with the Transiting Exoplanet Survey Satellite, or TESS, and found that all 6 stars had been misclassified as chemically peculiar stars.

The other 11 chemically peculiar stars appeared to show no periodic changes in their brightness, suggesting that they’re stationary. The team claimed that some CP1 and CP3 stars don’t rotate, but they identified cases in which CP2 and CP4 stars that ought to rotate appeared to be stationary. They suggested 2 potential reasons for this. One is that these CP2 and CP4 stars are misclassified, requiring more thorough analysis of their spectra to confirm their classifications. The other is that the stars rotate slowly, with rotational periods of 50 days or longer, which would be difficult to distinguish from those of totally stationary stars.

The team concluded that more astronomers should revisit the historical classifications of stars, especially as technology advances and more space-based telescopes become available. This strategy would allow future researchers to draw better data from research archives and catalogs. Additionally, they claimed that their method of pairing long-term monitoring via small satellites with TESS data is well-suited for refining classifications, identifying misclassified objects, and further exploring the structure and mechanics of chemically peculiar stars.

The post What makes ‘chemically peculiar stars’ peculiar? appeared first on Sciworthy.

Introduction This article is written by way of a reference for my longstanding PF colleague and prolific poster of challenging Maths/geometry problems @chwala . The particular post this article will discuss is an example of one such problem which he raised on Physics Forums. https://www.physicsforums.com/threads/find-angle-adb-in-this-isoceles-triangle-given-some-extra-information.1063874/ The Problem We take the liberty of including the original...