In a recent interview with Bloomberg, 23andMe CEO Anne Wojcicki said the company was considering splitting its consumer and therapeutics businesses in an effort to boost its stock price and maintain its listing. From a report: Bloomberg noted that the stock has lost more than 90% of its value since the company went public in 2021 through a SPAC merger. Bloomberg said the therapeutics business could be an attractive asset for a larger healthcare company. The business currently has two drug candidates in clinical trials and just received approval to commence testing for a third. The company's DNA database of more than 14 million customers is one of the world's largest. Currently, 23andMe derives most of its revenue from its consumer business, Bloomberg added.

23andMe's stock has been trading below $1 since December, hurt by revelations that hackers were able to access the personal information of around 50% of its subscribers. The company is also facing mounting litigation over the incident. The company is expected to release its Q4 earnings report after market close on Wednesday.

An AI chatbot helped increase the number of patients referred for mental-health services through England's National Health Service (NHS), particularly among underrepresented groups who are less likely to seek help, new research has found. MIT Tech Review: Demand for mental-health services in England is on the rise, particularly since the covid-19 pandemic. Mental-health services received 4.6 million patient referrals in 2022 -- the highest number on record -- and the number of people in contact with such services is growing steadily. But neither the funding nor the number of mental-health professionals is adequate to meet this rising demand, according to the British Medical Association.

The chatbot's creators, from the AI company Limbic, set out to investigate whether AI could lower the barrier to care by helping patients access help more quickly and efficiently. A new study, published this week in Nature Medicine, evaluated the effect that the chatbot, called Limbic Access, had on referrals to the NHS Talking Therapies for Anxiety and Depression program, a series of evidence-based psychological therapies for adults experiencing anxiety disorders, depression, or both. Venture capitalist Vinod Khosla comments on X: This landmark study codifies what we have believed for so long -- that AI will not only increase the quality of care but also massively improve its access, which is one of the largest barriers to good health in all corners of the globe.

The second of a pair of close flybys adds to the treasure trove of data that scientists have about Jupiter's volcanic moon. From a report: On Saturday, NASA's Juno orbiter got a second close-up with Io, Jupiter's third-largest moon and the most volcanic world of our solar system. The Juno spacecraft, which arrived at the gas giant in 2016, is on an extended mission to explore Jupiter's rings and moons. Its latest flyby, which complemented the mission's first close approach on Dec. 30, yielded even more views of the moon's hellish landscape.

Io's violent expulsions of sulfur and additional compounds give the moon its orange, yellow and blue hues. The process is similar to what happens around the volcanoes of Hawaii or the geysers in Yellowstone National Park, according to Scott Bolton, a physicist at the Southwest Research Institute who leads the Juno mission. "That must be what Io is like -- on steroids," he said. He added that it probably smells like those places, too.

Released on Sunday, the most recent shots of Juno are already ripe for discovery. Dr. Bolton saw on the surface of Io what appears to be a double volcanic plume spewing into space -- something that Juno has never caught before. Other scientists are noticing new lava flows and changes to familiar features spotted in past space missions like the Galileo probe, which made numerous close flybys of Io in the 1990s and 2000s. "That's the beauty of Io," said Jani Radebaugh, a planetary scientist at Brigham Young University who is not part of the Juno mission, but collaborates with the team on Io observations. Unlike our own moon, which remains frozen in time, Dr. Radebaugh said, "Io changes every day, every minute, every second."

Last June, Harvard professor Avi Loeb said he may have found fragments of alien technology from a meteor that landed in the waters off of Papua, New Guinea in 2014. "Since then, several researchers unrelated to the expedition have pushed back on his analysis," reports Boston Public Radio. "One October 2023 paper deemed the spherules were made by human-produced coal ash." Now, Loeb has published new findings that he claims debunk that theory.

"What we did is compare 55 elements from the periodic table in coal ash to those special spherules that we found," Loeb said. "And it's clearly very different." From the report: He said his work follows the scientific method: collecting materials, analyzing them and following the evidence. "It's not based on opinions," Loeb said. "And, of course, if you're not part of this scientific process and you are jealous of the attention that it gets, then you can raise a lot of criticism." When asked how he deals with that criticism, he said that, "by now, my skin turned into titanium." [...]

He believes more observatories should be built to expand on research of what's passing through closer to Earth, since astronomers are often fixated on faraway objects. "The best approach to figure it out is actually to do the scientific work of building observatories that look out and check what these objects are," Loeb said. "And if they happen to be birds, or airplanes, or Chinese balloons, so be it. We can move on after that. But we need to figure it out, it's our civil duty as scientists. "The universe is so vast that, rather than keep telling ourselves that there is nothing like us, we should search for it," he added.

Russian cosmonaut Oleg Kononenko set a world record for total time spent in space, "surpassing his compatriot Gennady Padalka who logged more than 878 days in orbit," reports Reuters. From the report: At 0830 GMT Kononenko broke the record, Roscosmos said. Kononenko is expected to reach a total of 1,000 days in space on June 5 and by late September he will have clocked 1,110 days. "I fly into space to do my favourite thing, not to set records," Kononenko told TASS in an interview from the International Space Station (ISS) where he is orbiting about 263 miles (423 km) from the earth. "I am proud of all my achievements, but I am more proud that the record for the total duration of human stay in space is still held by a Russian cosmonaut." The 59-year-old took the top spot from Padalka, who accumulated a total of 878 days, 11 hours, 29 minutes and 48 seconds, Roscosmos said.

Kononenko said that he worked out regularly to counter the physical effects of "insidious" weightlessness, but that it was on returning to earth that the realisation came of how much life he had missed out on. "I do not feel deprived or isolated," he said. "It is only upon returning home that the realisation comes that for hundreds of days in my absence the children have been growing up without a papa. No one will return this time to me." He said cosmonauts could now use video calls and messaging to keep in touch with relatives but getting ready for each new space flight became more difficult due to technological advances.

"The profession of a cosmonaut is becoming more complicated. The systems and experiments are becoming more complicated. I repeat, the preparation has not become easier," he said. Kononenko dreamed of going to space as a child and enrolled in an engineering institute, before undergoing cosmonaut training. His first space flight was in 2008. His current trip to the ISS launched last year on a Soyuz MS-24.

Julia Simon reports via NPR: In a D.C. courtroom, a trial is wrapping up this week with big stakes for climate science. One of the world's most prominent climate scientists is suing a right-wing author and a policy analyst for defamation. The case comes at a time when attacks on scientists are proliferating, says Peter Hotez, professor of Pediatrics and Molecular Virology at Baylor College of Medicine. Even as misinformation about scientists and their work keeps growing, Hotez says scientists haven't yet found a good way to respond. "The reason we're sort of fumbling at this is it's unprecedented. And there is no roadmap," he says. The climate scientist at the center of this trial is Michael Mann. The professor of earth and environmental science at the University of Pennsylvania gained prominence for helping make one of the most accessible, consequential graphs in the history of climate science. First published in the late 1990s, the graph shows thousands of years of relatively stable global temperatures. Then, when humans start burning lots of coal and oil, it shows a spike upward. Mann's graph looks like a hockey stick lying on its side, with the blade sticking straight up. The so-called "hockey stick graph" was successful in helping the public understand the urgency of global warming, and that made it a target, says Kert Davies, director of special investigations at the Center for Climate Integrity, a climate accountability nonprofit. "Because it became such a powerful image, it was under attack from the beginning," he says.

The attacks came from groups that reject climate science, some funded by the fossil fuel industry. In the midst of these types of attacks -- including the hacking of Mann's and other scientists' emails by unknown hackers -- Penn State, where Mann was then working, opened an investigation into his research. Penn State, as well as the National Science Foundation, found no evidence of scientific misconduct. But a policy analyst and an author wrote that they were not convinced. The trial in D.C. Superior Court involves posts from right-wing author Mark Steyn and policy analyst Rand Simberg. In an online post, Simberg compared Mann to former Penn State football coach Jerry Sandusky, a convicted child sex abuser. Simberg wrote that Mann was the "Sandusky of climate science," writing that Mann "molested and tortured data (PDF)." Steyn called Mann's research fraudulent. Mann sued the two men for defamation. Mann also sued the publishers of the posts, National Review and the Competitive Enterprise Institute, but in 2021, the court ruled they couldn't be held liable.

In court, Mann has argued that he lost funding and research opportunities. Steyn said in court that if Penn State's president, Graham Spanier, covered up child sexual assault, why wouldn't he cover up for Mann's science. The science in question used ice cores and tree rings to estimate Earth's past temperatures. "If Graham Spanier is prepared to cover up child rape, week in, week out, year in, year out, why would he be the least bit squeamish about covering up a bit of hanky panky with the tree rings and the ice cores?" Steyn asked the court. Mann and Steyn declined to speak to NPR during the ongoing trial. One of Simberg's lawyers, Victoria Weatherford, said "inflammatory does not equal defamatory" and that her client is allowed to express his opinion, even if it were wrong. "No matter how offensive or distasteful or heated it is," Weatherford tells NPR, "that speech is absolutely protected under the First Amendment when it's said against a public figure, if the person saying it believed that what they said was true."

An anonymous reader shares a report: With progress in the battle against cancer progressing slowly on Earth, California researchers have teamed up with astronauts to take the battle to the stars. In space, the weak pull of gravity, also known as microgravity, places cells under incredible stress, causing them to age more rapidly. This phenomenon allows scientists to witness the progression of cancer growth -- and the effect of cancer treatments -- much more rapidly than they could on Earth.

When the Axiom 3 spaceflight launched from Kennedy Space Center in Cape Canaveral, Fla., on Jan. 18, bound for the International Space Station, it took with it four crewmembers and some other unusual passengers -- miniature tumor organoids produced from the cells of cancer patients, grown in the lab by scientists at the University of California San Diego. Axiom 3 was slated for splashdown on Saturday but has been delayed until Tuesday, at the earliest, due to weather, according to SpaceX, which manufactured the Crew Dragon spacecraft used for the mission.

It wasn't the first time the team -- led by Dr. Catriona H.M. Jamieson, a hematologist and medical professor at the college -- sent such samples into space. It previously launched stem cells on multiple Space X flights and noticed that pre-leukemic changes occurred, unseen during the same timeframe in controls on the ground. "We said, 'Wait, what if you send cancer up?'" Jamieson tells Fortune. "'Will the cancer go from bad to worse?' And the answer is yes, under conditions of stress" caused by microgravity.

Researchers at Cern have submitted plans for a next-generation particle accelerator that's at least three times the size of the Large Hadron Collider. The Guardian reports: The Large Hadron Collider, built inside a 27km circular tunnel beneath the Swiss-French countryside, smashes together protons and other subatomic particles at close to the speed of light to recreate the conditions that existed fractions of a second after the big bang. The machine, the world's largest collider, was used in the discovery of the Higgs boson in 2012, nearly 50 years after the particle was proposed by Peter Higgs, the theoretical physicist at the University of Edinburgh, and several other researchers. The feat was honored with the Nobel prize in physics the following year.

But since the discovery of the Higgs boson, the collider has not revealed any significant new physics that might shed light on some of the deepest mysteries of the universe, such as the nature of dark matter or dark energy, why matter dominates over antimatter, and whether reality is permeated with hidden extra dimensions. Cern drew up plans for the next machine, the Future Circular Collider (FCC), in 2019. The $21.5 billion (20 billion euro) machine would have a 91km circumference and aim to smash subatomic particles together at a maximum energy of 100 teraelectronvolts (TeV). The Large Hadron Collider achieves maximum energies of 14TeV.

On Friday, the Cern council discussed a midterm review of a feasibility study for the FCC. If the plans go ahead, the organization would ask for approval in the next five years and hope to have the machine built and ready for operations in the 2040s when the LHC has completed its runs. Prof Fabiola Gianotti, the director general of Cern, said: "If approved, the FCC would be the most powerful microscope ever built to study the laws of nature at the smallest scales and highest energies, with the goal of addressing some of the outstanding questions in today's fundamental physics and our understanding of the universe."

An anonymous reader quotes a report from Popular Science: As detailed in the new issue of the journal Cell Stem Cell, University of Wisconsin-Madison researchers have developed a novel 3D-printing approach for creating cultures that grow and operate similar to brain tissue. While traditional 3D-printing involves layering "bio-ink" vertically like a cake, the team instead tasked their machine to print horizontally, as if playing dominoes. As New Atlas explains, researchers placed neurons grown from pluripotent stem cells (those capable of becoming multiple different cell types) within a new bio-ink gel made with fibrinogen and thrombin, biomaterials involved in blood clotting. Adding other hydrogels then helped loosen the bio-ink to solve for the 3 encountered during previous 3D-printed tissue experiments. According to Su-Chun Zhang, a research lead and UW-Madison professor of neuroscience and neurology, the resultant tissue is resilient enough to maintain its structure, but also sufficiently malleable to permit adequate levels of oxygen and nutrient intake for the neurons. "The tissue still has enough structure to hold together but it is soft enough to allow the neurons to grow into each other and start talking to each other," Zhang explains in a recent university profile.

Because of their horizontal construction, the new tissue cells formed connections not only within each layer, but across them, as well -- much like human neurons. The new structures could interact thanks to producing neurotransmitters, and even created support cell networks within the 3D-printed tissue. In these experiments, the team printed both cerebral cortex and striatum cultures. Although responsible for very different functions -- the former associated with thought, language, and voluntary movement; the latter tied to visual information -- the two 3D-printed tissues could still communicate, "in a very special and specific way," Zhang said. Researchers believe their technique isn't limited to creating just those two types of cultures, but hypothetically "pretty much any type of neurons [sic] at any time," according to Zhang. This means the 3D-printing method could eventually help study how healthy portions of the brain interact with parts affected by Alzheimers, examining cell signal pathways in Downs syndrome, as well as use tissue to test new drugs. "Our brain operates in networks," Zhang explained. "We want to print brain tissue this way because cells do not operate by themselves. They talk to each other. This is how our brain works and it has to be studied all together like this to truly understand it."

The "technology building blocks" for space solar are already available, reports Clean Technica. "It's just a matter of scaling, systems integration, and adjustments for space-hardiness."

And several groups are looking at it — including the U.S. Space Force To help push costs down, the California Institute of Technology has proposed a sandwich-type solar module that integrates solar harvesting along with conversion to a radio frequency into one compact package, accompanied by a built-in antenna. Last month researchers at the school wrapped up a months-long, in-space test of different types of solar cells. Another approach is illustrated by the Michigan startup Virtus Solis, an industry partner of the University of Bristol. Last June the company and the school received £3.3 million in funding from the UK Net Zero Innovation program, for developing an open-source model for testing the performance of large, centralized antennas in space. "The concept depends upon the use of gigascale antenna arrays capable of delivering over 2GW of power from space onto similar gigascale antenna arrays either at sea or on the ground," the school explained.

As for how such a thing would be launched into space, that's where the U.S. Space Force comes in. Last August, the Space Force awarded a small business contract to the U.S. startup Orbital Composites. The company is tasked with the mission of developing its patented "quantum antenna" and in-space fabrication tools for secure communications in space applications, including space-to-space as well as space-to-Earth and vice versa. The basic idea is to let 3D printing doing much of the work in space. According to Orbital, in-space fabrication would save more than 100 times the cost of applying conventional fabrication methods to large-scale orbiting antennas. "By harnessing the potential of In-Space Servicing, Assembly, and Manufacturing (ISAM), the company eyes the prospect of creating significantly larger space antennas," Orbital Composites explains. "By fabricating antennas in space, larger and more complex designs are possible that eliminate the constraints of launch and rocket fairings...."

If you're guessing that a hookup between Virtus and Orbital is in the works, that's a good guess. On February 1, at the SpaceCOM conference in Orlando, Florida, Virtus Solis let slip that it is working with Orbital Composites on a space solar pilot project. If all goes according to plan, the project will be up and running in 2027, deploying Virtus's robot-enabled fabrication system with Orbital's 3D printing. As of this writing the two companies have not posted details, but Space News picked up the thread. "The 2027 mission is designed to showcase critical power-generation technologies including in-space assembly of solar panels and transmission of more than one kilowatt to Earth," Space News explained. "The news release calls the 2027 mission "a precursor to large-scale commercial megawatt-class solar installations in space by 2030...."

To be clear, Orbital's press release about its new Space Force quantum antenna contract does not mention anything in particular about space solar. However, the pieces of the puzzle fit. Along with the Virtus and Grumman connections, in October of 2022 Orbital won a small business contract through SpaceWERX, the Space Force's innovative technologies funding arm, to explore the capabilities of ISAM systems.
"SpaceWERX comes under the umbrella of the U.S. Air Force's AFWERX innovation branch, which has developed a program called SSPIDR, short for Space Solar Power Incremental Demonstrations and Research Project," the article points out. (While Virtus believes most space-based solar power systems could deliver megawatt hours of electricity at prices comparable to today's market.)

An anonymous reader shared this report from Slate: Last November, the American Ornithological Society, or AOS, announced that it would change the common names of all American birds named after people. There are 152 such "eponymic" names (that is, birds that are named after a specific person, like Bicknell's Thrush) on the AOS' official checklist, and the group is planning to start with between 70 and 80 species predominantly found in the U.S. and Canada. In the coming years, birds like Cooper's Hawk, Wilson's Snipe, and Lincoln's Sparrow will be stripped of their eponyms and given new common English names.

The eponymic naming issue has been heating up in the bird world for a few years now. Birds got their English names when they were "discovered" by Western scientists, or otherwise identified as a new species. This meant ornithologists had the honor of coming up with whatever moniker they wanted, and frequently named birds in honor of a benefactor, a friend, or the person who shot the first known specimen. But a growing number of ornithologists and nonscientist birders are questioning why we're stuck with names decided on a whim hundreds of years ago, especially when the names aren't very good...

Rather than attempt the impossible task of reviewing the people with birds named after them one by one, the AOS said it would just scrap them all and start from scratch. But that's where the real challenge comes in — because lots of bird names are pretty bad. Not offensive bad, like named after a Confederate general, but just unsatisfactory bad. There was never any standardization for how common bird names were granted, which means those names are all over the place and provide little guidance for what renaming should look like.
Birds are named after their identifying features, size, habitat, the sound they make, or where they were first discovered. So the American Ornithological Society announced it will "conduct an open, inclusive, and scientifically rigorous pilot program in 2024 to develop its new approach to English bird names in the U.S. and Canada." [T]here are few specifics yet, and no easy way to organize the public and whittle down suggestions in the lawless and nonsensical world of bird names. But the AOS has committed to change: Unlike the closed-door decisions of the past, this will be a public process. The plan is to take suggestions — from field marks, Indigenous names, colloquialisms ... from anywhere — narrow it down, somehow, to a few options, and let people decide... Our new bird names won't be ideal — none of them are — but, for the first time, they will belong to us.

"Japan's first moon mission has likely come to an end after a surprising late-game comeback," reports Mashable, "with the spacecraft taking one last photo of its surroundings before the deep-freeze of night... showing ominous shadows cast upon a slope of the Shioli crater, its landing site on the near side of the moon." Since Monday, the spacecraft has analyzed rocks around the crater with a multi-band spectral camera. JAXA picked the landing spot because of what it could tell scientists about the moon's formation... The special camera completed its planned observation, able to study more targets than originally expected, according to an English translation of a news release from the space agency... "Based on the large amount of data we have obtained, we are proceeding with (analyses) to identify rocks and estimate the chemical composition of minerals, which will help solve the mystery of the origin of the moon," JAXA said in a statement translated by Google...

The spacecraft has now entered a dormant state, prompted by nightfall on the moon. Because one rotation of the moon is about 27 Earth days, the so-called "lunar night," when the moon is no longer receiving sunlight, lasts about two weeks. Not much can survive the -270 degrees Fahrenheit brought on by darkness — not even robots. In this freezing temperature, soldered joints on hardware and mechanical parts break, and batteries die. But rest assured, the JAXA team will try to communicate with its scrappy moon lander when the sun rises again.
In mid-week Japan's space agency posted that "Although SLIM was not designed for the harsh lunar nights, we plan to try to operate again from mid-February, when the Sun will shine again on SLIM's solar cells."

Later they posted that they'd sent a command to turn on SLIM's communicator again "just in case, but with no response, we confirmed SLIM had entered a dormant state. This is the last scene of the Moon taken by SLIM before dusk."

Nicholas Wise is a fluid dynamics researcher who moonlights as a scientific fraud buster, reports Science magazine. And last June he "was digging around on shady Facebook groups when he came across something he had never seen before." Wise was all too familiar with offers to sell or buy author slots and reviews on scientific papers — the signs of a busy paper mill. Exploiting the growing pressure on scientists worldwide to amass publications even if they lack resources to undertake quality research, these furtive intermediaries by some accounts pump out tens or even hundreds of thousands of articles every year. Many contain made-up data; others are plagiarized or of low quality. Regardless, authors pay to have their names on them, and the mills can make tidy profits.

But what Wise was seeing this time was new. Rather than targeting potential authors and reviewers, someone who called himself Jack Ben, of a firm whose Chinese name translates to Olive Academic, was going for journal editors — offering large sums of cash to these gatekeepers in return for accepting papers for publication. "Sure you will make money from us," Ben promised prospective collaborators in a document linked from the Facebook posts, along with screenshots showing transfers of up to $20,000 or more. In several cases, the recipient's name could be made out through sloppy blurring, as could the titles of two papers. More than 50 journal editors had already signed on, he wrote. There was even an online form for interested editors to fill out...

Publishers and journals, recognizing the threat, have beefed up their research integrity teams and retracted papers, sometimes by the hundreds. They are investing in ways to better spot third-party involvement, such as screening tools meant to flag bogus papers. So cash-rich paper mills have evidently adopted a new tactic: bribing editors and planting their own agents on editorial boards to ensure publication of their manuscripts. An investigation by Science and Retraction Watch, in partnership with Wise and other industry experts, identified several paper mills and more than 30 editors of reputable journals who appear to be involved in this type of activity. Many were guest editors of special issues, which have been flagged in the past as particularly vulnerable to abuse because they are edited separately from the regular journal. But several were regular editors or members of journal editorial boards. And this is likely just the tip of the iceberg.
The spokesperson for one journal publisher tells Science that its editors are receiving bribe offers every week..

Thanks to long-time Slashdot reader schwit1 for sharing the article..

The New York Times reports on a potential fix for global warming being proiposed by "a small but growing number of astronomers and physicists... the equivalent of a giant beach umbrella, floating in outer space. " The idea is to create a huge sunshade and send it to a far away point between the Earth and the sun to block a small but crucial amount of solar radiation, enough to counter global warming. Scientists have calculated that if just shy of 2% of the sun's radiation is blocked, that would be enough to cool the planet by 1.5 degrees Celsius, or 2.7 Fahrenheit, and keep Earth within manageable climate boundaries. The idea has been at the outer fringes of conversations about climate solutions for years. But as the climate crisis worsens, interest in sun shields has been gaining momentum, with more researchers offering up variations. There's even a foundation dedicated to promoting solar shields.

A recent study led by the University of Utah explored scattering dust deep into space, while a team at the Massachusetts Institute of Technology is looking into creating a shield made of "space bubbles." Last summer, Istvan Szapudi, an astronomer at the Institute for Astronomy at the University of Hawaii, published a paper that suggested tethering a big solar shield to a repurposed asteroid. Now scientists led by Yoram Rozen, a physics professor and the director of the Asher Space Research Institute at Technion-Israel Institute of Technology, say they are ready to build a prototype shade to show that the idea will work.

To block the necessary amount of solar radiation, the shade would have to be about 1 million square miles, roughly the size of Argentina, Rozen said. A shade that big would weigh at least 2.5 million tons — too heavy to launch into space, he said. So, the project would have to involve a series of smaller shades. They would not completely block the sun's light but rather cast slightly diffused shade onto Earth, he said. Rozen said his team was ready to design a prototype shade of 100 square feet and is seeking between $10 million and $20 million to fund the demonstration. "We can show the world, 'Look, there is a working solution, take it, increase it to the necessary size," he said...

Rozen said the team was still in the predesign phase but could launch a prototype within three years after securing funds. He estimated that a full-size version would cost trillions (a tab "for the world to pick up, not a single country," he said) but reduce the Earth's temperature by 1.5 Celsius within two years. "We at the Technion are not going to save the planet," Rozen said. "But we're going to show that it can be done."

Jennifer Ouellette reports via Ars Technica: A typical lawn sprinkler features various nozzles arranged at angles on a rotating wheel; when water is pumped in, they release jets that cause the wheel to rotate. But what would happen if the water were sucked into the sprinkler instead? In which direction would the wheel turn then, or would it even turn at all? That's the essence of the "reverse sprinkler" problem that physicists like Richard Feynman, among others, have grappled with since the 1940s. Now, applied mathematicians at New York University think they've cracked the conundrum, per a recent paper published in the journal Physical Review Letters -- and the answer challenges conventional wisdom on the matter. "Our study solves the problem by combining precision lab experiments with mathematical modeling that explains how a reverse sprinkler operates," said co-author Leif Ristroph of NYU's Courant Institute. "We found that the reverse sprinkler spins in the 'reverse' or opposite direction when taking in water as it does when ejecting it, and the cause is subtle and surprising." [...]

Enter Leif Ristroph and colleagues, who built their own custom sprinkler that incorporated ultra-low-friction rotary bearings so their device could spin freely. They immersed their sprinkler in water and used a special apparatus to either pump water in or pull it out at carefully controlled flow rates. Particularly key to the experiment was the fact that their custom sprinkler let the team observe and measure how water flowed inside, outside, and through the device. Adding dyes and microparticles to the water and illuminating them with lasers helped capture the flows on high-speed video. They ran their experiments for several hours at a time, the better to precisely map the fluid-flow patterns.

Ristroph et al. found that the reverse sprinkler rotates a good 50 times slower than a regular sprinkler, but it operates along similar mechanisms, which is surprising. "The regular or 'forward' sprinkler is similar to a rocket, since it propels itself by shooting out jets," said Ristroph. "But the reverse sprinkler is mysterious since the water being sucked in doesn't look at all like jets. We discovered that the secret is hidden inside the sprinkler, where there are indeed jets that explain the observed motions." A reverse sprinkler acts like an "inside-out rocket," per Ristroph, and although the internal jets collide, they don't do so head-on. "The jets aren't directed exactly at the center because of distortion of the flow as it passes through the curved arm," Ball wrote. "As the water flows around the bends in the arms, it is slung outward by centrifugal force, which gives rise to asymmetric flow profiles." It's admittedly a subtle effect, but their experimentally observed flow patterns are in excellent agreement with the group's mathematical models.