Enlarge / All steroids past and present share the complex ringed structure but differ in terms of the atoms attached to those rings. (credit: KATERYNA KON/SCIENCE PHOTO LIBRARY)

All of the organisms we can see around us—the plants, animals, and fungi—are eukaryotes composed of complex cells. Their cells have many internal structures enclosed in membranes, which keep things like energy production separated from genetic material, and so on. Even the single-celled organisms on this branch of the tree of life often have membrane-covered structures that they move and rearrange for feeding.

Some of that membrane flexibility comes courtesy of steroids. In multicellular eukaryotes, steroids perform various functions; among other things, they’re used as signaling molecules, like estrogen and testosterone. But all eukaryotes insert various steroids into their membranes, increasing their fluidity and altering their curvature. So the evolution of an elaborate steroid metabolism may have been critical to enabling complex life.

Now, researchers have traced the origin of eukaryotic steroids almost a billion years further back in time. The results suggest that many branches of the eukaryotic family tree once made early versions of steroids. But our branch evolved the ability to produce more elaborate ones—which may have helped us outcompete our relatives.

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Enlarge / Artist's conception of a gamma-ray burst. (credit: NASA)

Supernovae are some of the most energetic events in the Universe. And a subset of those involves gamma-ray bursts, where a lot of the energy released comes from extremely high-energy photons. We think we know why that happens in general terms—the black hole left behind after the explosion expels jets of material at nearly the speed of light. But the details of how and where these jets produce photons are not at all close to being fully worked out.

Unfortunately, these events happen very quickly and very far away, so it's not easy to get detailed observations of them. However, a recent gamma-ray burst that's been called the BOAT (brightest of all time) may be providing us with new information on the events within a few days of a supernova's explosion. A new paper describes data from a telescope that happened to be both pointing in the right direction and sensitive to the extremely high-energy radiation produced by the event.

I need a shower

The "telescope" mentioned is the Large High Altitude Air Shower Observatory (LHAASO). Based nearly three miles (4,400 meters) above sea level, the observatory is a complex of instruments that aren't a telescope in the traditional sense. Instead, they're meant to capture air showers—the complex cascade of debris and photons that are produced when high-energy particles from outer space slam into the atmosphere.

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Anyone who has taken a basic computer science class has undoubtedly spent time devising a sorting algorithm—code that will take an unordered list of items and put them in ascending or descending order. It's an interesting challenge because there are so many ways of doing it and because people have spent a lot of time figuring out how to do this sorting as efficiently as possible.

Sorting is so basic that algorithms are built into most standard libraries for programming languages. And, in the case of the C++ library used with the LLVM compiler, the code hasn't been touched in over a decade.

But Google's DeepMind AI group has now developed a reinforcement learning tool that can develop extremely optimized algorithms without first being trained on human code examples. The trick was to set it up to treat programming as a game.

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Enlarge / On May 22, John Timmer (left) moderated a panel featuring Karin Bok (center) and Nathaniel Wang (right) for the Ars Frontiers 2023 session titled, "Beyond COVID: What Does mRNA Technology Mean for Disease Treatment?" (credit: Ars Technica)

The world of biomedicine has developed a lot of technology that seems a small step removed from science fiction, but the public isn't aware of much of it. One of those technologies, mRNA-based vaccines, however, has been a big exception, as a lot of the public tracked the technology's development as a key step toward emerging from the worst of the pandemic and then received the vaccines in droves.

mRNA technology has a lot of potential applications beyond COVID, and we talked a bit about those during the "Beyond COVID: What Does mRNA Technology Mean for Disease Treatment?" panel at last week's Ars Frontiers event. We've archived the panel on YouTube; if you want to focus on the discussion about mRNA therapies, you can start at the 1-hour, 55-minute mark.

mRNA is a nucleic acid molecule that instructs the cell to make specific proteins. When used as vaccines, the instructions call for a protein produced by a pathogen, such as a virus. "It helps put up a wanted poster for the immune system," was how Nathaniel Wang, co-founder and CEO of Replicate Bioscience, put it.

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In December 2022, founder Elon Musk gave an update on his other, other company, the brain implant startup Neuralink. As early as 2020, the company had been saying it was close to starting clinical trials of the implants, but the December update suggested those were still six months away. This time, it seems that the company was correct, as it now claims that the Food and Drug Administration (FDA) has given its approval for the start of human testing.

Neuralink is not ready to start recruiting test subjects, and there are no details about what the trials will entail. Searching the ClinicalTrials.gov database for "Neuralink" also turns up nothing. Typically, the initial trials are small and focused entirely on safety rather than effectiveness. Given that Neuralink is developing both brain implants and a surgical robot to do the implanting, there will be a lot that needs testing.

It's likely that these will focus on the implants first, given that other implants have already been tested in humans, whereas an equivalent surgical robot has not.

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Enlarge / Wetlands like this may end up a complicated patchwork of regulated and unregulated areas thanks to the latest Supreme Court decision. (credit: Stefano Madrigali)

On Thursday, the US Supreme Court issued a ruling that severely limits the Environmental Protection Agency's ability to regulate pollution under the Clean Water Act. The ruling applies to wetlands that are connected to bodies of water that fall under the Clean Water Act's regulatory scheme, with the court now ruling that those connections need to be direct and contiguous for the act to apply. This would remove many wetlands separated by small strips of land—including artificial structures like levees—from oversight by the EPA.

The decision is a somewhat unusual one in that all nine justices agree that the people who originally sued the EPA should prevail. But there was a very sharply worded 5-4 disagreement over what the word "adjacent" means.

Whose waters are these?

The Clean Water Act was a major piece of environmental regulation due to the sometimes horrific pollution prevalent in the early 1970s. Its text applies regulations to the "waters of the United States," a term that has proven sufficiently vague that it has been the subject of various lawsuits and federal regulatory policies over the years. Several geographic features—seasonal streams, human-made water features, and marshlands without a direct connection to rivers—have all been subject to dispute.

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Enlarge (credit: Douglas Rissing)

Many Americans have been shocked by the frequency with which people who claim to love our democracy have supported blatantly undemocratic efforts to limit people's ability to vote or to selectively discard votes already cast. Unfortunately, this sort of democratic backsliding is far from a US-specific problem. Despite widespread support for democracy in countries like Venezuela and Hungary, people have turned out in large numbers to vote for autocrats.

A new study performed in the US suggests at least one explanation for the problem: People across the political spectrum appear to believe their political opponents are likely to take anti-democratic action if given the opportunity. And the strength of this belief correlates with a slightly increased willingness to take those actions first.

Nobody says they like this stuff

The finding, from a University of California, Berkeley-Massachusetts Institute of Technology collaboration, is based on demographically representative survey populations, which were asked about several potential anti-democratic actions. For example, those surveyed were asked if they agreed with reducing the number of voting facilities in towns that support the opposing party. Similar questions got at things like banning rallies, limiting freedom of expression, ignoring court rulings, or resorting to violence. After being asked for their own opinions, people were then asked whether they thought their political opponents supported these anti-democratic approaches.

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Enlarge (credit: John Timmer)

Foldable bikes offer a pretty obvious trade-off: the convenience of something you can easily pick up and store in the corner of an office or small apartment, but with some compromises in the cycling experience. Typically, putting a greater emphasis on one of those will mean sacrificing a bit on the other.

But e-bikes offer the possibility to sidestep some of that trade-off, boosting aspects of cycling performance without adding much in the way of added bulk. And the Gocycle G4 provides an excellent demonstration of how well that formula can work out, offering excellent performance in a thoughtfully designed package that is easy to pick up and lug around. It's not so good that it will completely replace a regular bike, but it comes a lot closer than I expected, and it has a number of brilliantly designed features.

All that said, the bike still has a couple of issues that temper my enthusiasm a bit.

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Enlarge / An artist's conception of what a volcano-rich exoplanet might look like. (credit: NASA’s Goddard Space Flight Center/Chris Smith)

For most of the exoplanets we've discovered, we know very few details. We know a bit about the star they orbit and maybe a partial list of other planets in the same system. And we typically know either how large they are or how heavy they are. It's not a lot to go on.

But we can infer a lot when we start combining those details. That's the case for a newly discovered exoplanet orbiting a small star about 90 light-years from Earth. The planet itself has a radius and mass very similar to the Earth's, suggesting it also has a rocky composition. Based on what we know of the star, it can potentially contain liquid water. And, based on the forces exerted by nearby planets, it's likely to have very active geology, potentially including volcanoes.

An extra, extra-solar planet

The exosolar system at the star LP 791-18 was first discovered by the Transiting Exoplanet Survey Satellite (TESS). TESS had spotted two planets orbiting LP 791-18, which is one of the smallest—and thus dimmest—stars known to host planets. The innermost planet, LP 791-18b, is about 20 percent larger than Earth and takes less than a day to complete an orbit, meaning it's close enough to the star to be very hot. Farther out, with a five-day orbit, is LP 791-18c, a sub-Neptune that's more than double Earth's size.

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Enlarge / These complex creatures seem to be the earliest branch of the animal tree. We're more closely related to sponges than we are to them. (credit: Getty Images)

Ask someone to think of an animal, and chances are they'll come up with one of our relatives among the mammals. A few people might go further afield and mention other vertebrates, like birds and fish. But these barely scratch the surface of animal diversity, with things like cephalopods, insects, and echinoderms all having distinct features.

And that's before you get to the really weird stuff, like the radially symmetric Cnidarians, or the sponges that lack muscle and nerve cells. Or the comb jellies, which move themselves around by spinning lots of thread-like cilia. Or the truly bizarre placozoans, disk-like creatures that have two sides but no interior and digest things on their surface.

For people who tend to think that evolution involves adding ever-greater complexity to organisms, it's tempting to imagine that the animal family tree came about by progressively adding more stuff, like nerve cells and muscles. But there has been a steady flow of genetic studies that hint that there are two separate lineages that ended up with nerve cells. The results of these studies were a bit dependent upon the genes and species chosen for the analysis. But a new study that's not as dependent upon individual genes now firmly places sponges as more closely related to humans than some other animals with a nervous system.

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Enlarge / Lutetium, the metal at the core of superconductivity claims. (credit: L Yagovy)

On Monday, the journal Nature released a report from Nanjing University researchers that had attempted to replicate an earlier paper that described a compound that superconducted at room temperature and relatively moderate pressures. Despite persuasive evidence that they've produced the same chemical, the team indicates they see no sign of superconductivity, even down to extremely low temperatures.

The failure will undoubtedly raise further questions about the original research, which came from a lab that had an earlier paper on superconductivity retracted.

Bold claims

The work is part of a growing body of literature on metals complexed with hydrogen. These hydrogen-rich chemicals can form at ambient conditions, but added pressure can force additional hydrogen atoms into the structure. The resulting high-pressure compounds have ingredients—spare electrons from the metal, light nuclei from the hydrogen—that are thought to favor the formation of Cooper pairs from the electrons, a key ingredient in superconductivity. And a number of hydrogen-rich chemicals have been found to superconduct at over 200 K (-75° C) if the pressure is high enough.

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Enlarge / The arc of thin, distorted objects around the center of this image is a clear indication of gravitational lensing. (credit: Patrick Kelly, University of Minnesota)

Anyone who has ever measured something twice, like the width of a doorway, and gotten two different answers knows how annoying it can be. Now imagine you're a physicist, and what you're measuring tells us something fundamental about the Universe. There are a number of examples like this—we can't seem to get measurements to agree on how long neutrons survive outside of atomic nuclei, for example.

But few of these are more fundamental to the Universe's behavior as disagreements over what's called the Hubble Constant, a measure of how quickly the Universe is expanding. We've measured it using information in the cosmic microwave background and gotten one value. And we've measured it using the apparent distance to objects in the present-day Universe and gotten a value that differs by about 10 percent. As far as anyone can tell, there's nothing wrong with either measurement, and there's no obvious way to get them to agree.

Now, researchers have managed to make a third, independent measure of the Universe's expansion by tracking the behavior of a gravitationally lensed supernova. When first discovered, the lens had created four images of the supernova. But sometime later, a fifth appeared, and that time delay is influenced by the Universe's expansion—and thus the Hubble constant.

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Enlarge / Natural gas plants like these may find themselves burning hydrogen over the next 20 years. (credit: Ron and Patty Thomas)

Today, the Biden administration formally announced its planned rules for limiting carbon emissions from the electrical grid. The rules will largely take effect in the 2030s and apply to gas- and coal-fired generating plants. Should the new plan go into effect, the operators of those plants will either need to capture carbon or replace a large fraction of their fuel with hydrogen. The rules will likely hasten coal's disappearance from the US grid and start pushing natural gas turbines to a supplemental source of power.

Whether they go into effect will largely depend on legal maneuvering and the results of future elections. But first, the rules themselves.

Clearing the air

In 2007, the US Supreme Court ruled that the Clean Air Act applied to greenhouse gas emissions. This allows the EPA to set state-level standards to limit the release of greenhouse gasses, with the states given some leeway on how they reach those standards. Since then, the court has clarified that these standards must be met on a per-plant basis rather than at the grid level; the EPA can't set rules that assume that the grid has more generation from solar and less from coal plants.

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Enlarge / The quantum network is a bit bulkier than Ethernet. (credit: ETH Zurich / Daniel Winkler)

A new experiment uses superconducting qubits to demonstrate that quantum mechanics violates what's called local realism by allowing two objects to behave as a single quantum system no matter how large the separation between them. The experiment wasn't the first to show that local realism isn't how the Universe works—it's not even the first to do so with qubits.

But it's the first to separate the qubits by enough distance to ensure that light isn't fast enough to travel between them while measurements are made. And it did so by cooling a 30-meter-long aluminum wire to just a few milliKelvin. Because the qubits are so easy to control, the experiment provides a new precision to these sorts of measurements. And the hardware setup may be essential for future quantum computing efforts.

Getting real about realism

Albert Einstein was famously uneasy with some of the consequences of quantum entanglement. If quantum mechanics were right, then a pair of entangled objects would behave as a single quantum system no matter how far apart the objects were. Altering the state of one of them should instantly alter the state of the second, with the change seemingly occurring faster than light could possibly travel between the two objects. This, Einstein argued, almost certainly had to be wrong.

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Enlarge (credit: Tad Denson)

Oil and gas producers in the US are required by law to seal and cap their wells once they're finished producing. But a new survey of wells along the Gulf of Mexico coast indicates that there are 14,000 wells that aren't producing, are unlikely to be brought back into service, and are uncapped.

The bad news is that the estimated cost of capping them all would run into the area of $30 billion dollars. The good news is that, in most cases, one of the major oil companies will be responsible for these costs.

Put a cork in it

The basic risk of uncapped wells is that material doesn't necessarily stop coming out of them when the equipment the well was connected to is switched off and removed. One obvious potential problem is continued seepage of hydrocarbons. Light material like methane and simple hydrocarbons typically end up being digested by microbial life, which converts it to carbon dioxide that will typically find its way to the atmosphere. More complicated molecules will be insoluble and remain behind as contamination.

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Enlarge / CDC Director Rochelle Walensky testifying before Congress. (credit: Drew Angerer)

On Friday, the Centers for Disease Control and Prevention Director Rochelle Walensky announced that she'd be stepping down from her position at the end of June. The announcement came the same day that the World Health Organization announced that COVID no longer constituted an emergency, and Walensky's resignation letter made reference to that: “The end of the COVID-19 public health emergency marks a tremendous transition for our country, for public health, and in my tenure as CDC Director.”

Walensky took on the directorship of the CDC at a very challenging time. The agency was dealing with a number of self-inflicted wounds, such as the failure of its initial tests for SARS-CoV-2 and confused advice on the value of masks. Layered on top of that was a degree of political interference from a White House that wanted to minimize the risk and damage of the pandemic. This included the sidelining of CDC experts who gave realistically grim warnings at the start of the pandemic and the editing of public health guidance by White House political appointees. By the start of the Biden administration, the once-flagship public health organization had lost a lot of its credibility and suffered from severe morale problems.

Walensky took on the task of restoring trust and reforming the agency, starting a restructuring program meant to get CDC to focus on getting the data needed to craft public health advice rather than generate academic publications. Better communication to the public was also a major goal of the reforms.

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Enlarge (credit: Arthur Morris)

Reasoning about probabilities is something humans can't always manage especially well, but it's clearly a skill we're capable of. In the wider world of animals, however, there are very few species we can say are able to make choices based on probabilities. So far, the only animals that have demonstrated the ability to make choices based on statistics are our fellow primates and the kea, an alpine parrot from New Zealand.

All the species where this ability had been seen have a large brain relative to their body size, a feature that is associated with many advanced cognitive capabilities. So it was reasonable to conclude that statistical reasoning required some significant mental horsepower. But a study released on Thursday indicates that managing probabilities may be more widespread than we think since an animal with a relatively small brain—the giraffe—is apparently capable of it.

Chances are...

Reasoning based on probability and statistics sounds complicated, but we do it all the time. We weigh the likelihood of various factors when deciding what to bet in poker or which route to take on a commute. We're not always good about it; if we were, we'd freak out more about driving than we do about air travel. But the capacity to do so is there.

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We have various ways of seeing what the brain is up to, from low-resolution electrodes that track waves of activity that ripple across the brain, to implanted electrodes that can follow the activity of individual cells. Combined with a detailed knowledge of which regions of the brain are involved in specific processes, we've been able to do remarkable things, such as using functional MRI (fMRI) to determine what letter a person was looking at or an implant to control a robotic arm.

But today, researchers announced a new bit of mind reading that's impressive in its scope. By combining fMRI brain imaging with a system that's somewhat like the predictive text of cell phones, they've worked out the gist of the sentences a person is hearing in near real time. While the system doesn't get the exact words right and makes a fair number of mistakes, it's also flexible enough that it can reconstruct an imaginary monologue that goes on entirely within someone's head.

Making functional MRI functional

Functional MRI is a way of seeing what parts of the brain have been active. By tuning the sensitivity of the imaging to pick up differences in the flow of blood, it's possible to identify areas within the brain that are replenishing their energy after having processed some information. It has been extremely useful for understanding how the brain operates, but it also has some significant limitations.

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Enlarge / The next generation of reactors may be small and modular and use different coolants. (credit: Getty Images)

"The race against climate change is both a marathon and a sprint," declares a new report from the US National Academies of Science. While we need to start decarbonizing immediately with the tech we have now—the sprint—the process will go on for decades, during which technology that's still in development could potentially play a critical role.

The technology at issue in the report is a new generation of nuclear reactors based on different technology; they're smaller and easier to build, and they could potentially use different coolants. The next generation of designs is working to avoid the delays and cost overruns that are crippling attempts to build additional reactors both here and overseas. But their performance in the real world will remain an unknown until next decade at the earliest, placing them squarely in the "marathon" portion of the race.

The new report focuses on what the US should do to ensure that the new generation of designs has a chance to be evaluated on its merits.

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Enlarge / WASP-39b is much closer to its host star than any of our Solar System's planets are to the Sun. (credit: NASA)

Up until a few decades ago, the only planets we knew about were in our own Solar System, and that shaped the way we thought about planet formation and planetary chemistry. Now, with the identification of a large population of exoplanets, we have a lot of examples of things we've never seen before: mini Neptunes, super Earths, and hot Jupiters abound.

Figuring out what all these new things tell us is a bit of a mixed bag. It's relatively easy to determine a planet's density and how much energy it will receive from its host star. But a given density is typically compatible with a range of materials—solid rock can work out to be the same as a large metal core and puffy atmosphere, for example. And the planet's temperature will depend heavily on things like the composition of its atmosphere and how much light its surface reflects.

So figuring out what we're looking at when we see data on an exoplanet is hard. But with the successful commissioning of the Webb Space Telescope, we're starting to get a bit further. In Wednesday's issue of Nature, scientists used data from the new telescope to infer the chemistry of a hot gas giant and find that there are things going on that we wouldn't see in our own Solar System.

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