Acer’s Chromebook Spin 713 has been at the top of our Best Chromebook list for a few years running now. It’s one of the most beloved Chromebooks of the past several years, and it had a laundry list of things going for it: blazing fast Intel processors, a crisp and high-resolution 3:2 screen, a generous port selection with Thunderbolt 4, all-day battery life, and one of the better keyboards you could find in the Chromebook space. I had very high hopes for its sequel, the Chromebook Spin 714.
So it brings me no pleasure to report that the Chromebook Spin 714 is worse than the 713. That doesn’t make it a terrible computer — and at my Core i5 / 8GB / 256GB unit’s MSRP of $729.99, many of these flaws are more forgivable than they would be at a price of, say, $1,000. But I do see it, unfortunately, as a step back. Here’s why.
The major area in which this device has improved over the 713 is speed. The 714 is one of few Chromebooks that comes with Intel’s 12th Gen processors. It is lightning fast. It handled my heavy multitasking workload just fine, and I can’t imagine it would have a problem running things in Linux, either. Nothing I threw at it — even when I was hopping between 20-25 tabs and apps — generated any heat or made the fans spin up at all. While I tested last year’s Spin 713, the fans were raging basically the whole time. So that’s a welcome improvement.
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This is also, in my opinion, a slightly better-looking computer than the 713. I won’t go so far as to call it a good-looking device — the design is still somewhat boring and drab, and an “Antimicrobial Corning Gorilla Glass” logo etched into the top bezel is particularly unappealing. Still, there are some nice accents around the touchpad that make everything look more professional. And the finish is high-quality — this device was battered around in my backpack without a scratch. Visually and materially, this device is a step up from the 713. (But, I cannot overemphasize, it still looks boring.)
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And finally, there’s a garaged stylus. It lives in a tiny slot in the bottom right corner of the device, and it’s very easy to slip in and out. Writing with it was a mixed bag — the texture was smooth, but the hinge isn’t quite sturdy enough to keep the screen firmly in place while I was writing in laptop mode or tablet mode. I didn’t love the give it had in both cases. To start using the Acer Chromebook Spin 714, you’ll need to agree to the following: You can also say yes or no to the following: In total, that’s three mandatory agreements and five optional agreements to use the Acer Chromebook Spin 714. Okay, time to talk about some of the more puzzling changes Acer made. First, the display. So, yes, the Spin 714’s screen is slightly larger. However, the Spin 713 had one of the most exceptional screens that has ever been put on a Chromebook. It was 3:2 with 2256 x 1504 resolution. It was so roomy, there was zero glare, colors were vivid, and all of this was a huge part of the reason that Chromebook 713 was topping Best Chromebook pages all over the internet. I am picturing that screen right now, and I miss it so much. Please come back to me. Anyway, that’s not the screen the 714 has. This device sports a 1920 x 1200, 16:10 panel. It reaches 340 nits of brightness, whereas the 713 easily passed 400. Look, this screen is fine, but like… meh. It’s fine. Second, one of the ports is gone. Acer removed the microSD slot that the Spin 713 had. The other ports here are fine (you get two USB-C with Thunderbolt 4, one USB 3.2 Gen 1, one HDMI, and one headphone jack). It’s just that the 713 also had all that, plus a microSD slot. And then we get to the battery life. Once again, Intel 12th Gen is displaying shorter battery life than Intel 11th Gen did. I averaged seven and a half hours out of the 11th Gen device (which, bear in mind, had a brighter and higher-resolution screen). I averaged four hours and 56 minutes of continuous work use, at 50 percent brightness, out of this one. And while you may get higher numbers than I did here depending on your workload, it seems very likely that most people will get a sizeably shorter time out of the Spin 714 than they would out of its predecessor. (Charging time was speedy, at least — the 714 juiced up to an hour in just 46 minutes, an improvement over last year.) There are other minor things, too — the 714’s touchpad is smaller, its chassis is thicker and heavier, and there’s no fingerprint sensor. And then, all of that aside, there is the fact that they made the device more expensive. This unit, remember, is $729.99 — a Core i5 / 8GB / 256GB model of the 713 was $699. My model is the cheapest one I’ve been able to find online — I’m also seeing a Core i5 / 16GB unit and a Core i7 / 16GB unit both listed for just over $1,000. Sure, maybe the included stylus and slightly larger screen would justify that price increase in a vacuum. But then I look at the long list of things missing from the 714, the ways in which it’s a step back, and I’m just not convinced. I don’t want to brush past how much extra power the Spin 714 has. The silent fans and cold plastic were very much a noticeable improvement. This likely remains one of the most powerful Chromebooks — if not most powerful devices — you can buy for $729.99. But what makes me sad is that the Spin 713 used to be that. The Spin 713 blew its competitors out of the water with benchmark scores. But it was also great in so many other ways. It had a great screen. It had great battery life. It had a great port selection. Really, the only thing to complain about was the subpar audio (which remains subpar on the 714). The Spin 714, by contrast, mostly has the powerful specs going for it. And while that power certainly keeps it in the conversation, it is not at all the slam-dunk purchase that the 713 was. Records of solar eclipses from a millennium and a half ago have allowed scientists to refine measurements of Earth’s changing rotation. A painstaking review of historical documents from the Byzantine Empire has given scientists timings and locations for five solar eclipses. The results, although consistent with previous findings, place new, tighter constraints on Earth’s variable spin rate, giving us a better understanding of how our planet is changing over time. The length of a day seems like a pretty reliable, unchanging metric. Twenty-four hours in a day: 86,400 seconds. That’s what all our clocks count out, day after day after day. That’s the beat to which we live our lives. But it’s a bit of an illusion. The rate at which our planet turns slows and accelerates in patterns influenced by a variety of factors both underfoot and overhead. Consider the long-term trend in which our days are gradually stretching ever longer. Based on the fossil record, scientists have deduced that days were just 18 hours long 1.4 billion years ago, and half an hour shorter than they are today 70 million years ago. We seem to be gaining 1.8 milliseconds a century. Then there’s the strange six-year oscillations: scientists have figured out that Earth’s days undergo time variations of plus or minus 0.2 seconds every six years or so. A wobble in Earth’s rotational axis seems to be able to produce anomalies, like a peculiarly short day recorded last year. Just for something different. From core activity, to atmospheric drag, to the expanding orbit of the Moon, a number of factors can influence the actual length of Earth’s days. The discrepancy between the accepted length of a day which we all set our watches to (Universal Time, or UT) and a standardized metric precisely counted out by atomic clocks (Terrestrial Time, or TT) – the most accurate timekeeping devices we have – is a measurement known as ΔT (delta-T). ΔT becomes really important when it comes to solar eclipses. That’s because the positions of the Sun and the Moon are calculated and predicted using TT, but the Moon’s shadow will be falling on a planet operating under UT. So you need to know the difference between the two times in order to predict from where on Earth the eclipse will be visible. But, it also works in reverse! If you have the precise time and location of a solar eclipse, you can work out ΔT. Scientists have been able to work out ΔT from historical records from China, Europe and the Middle East. Three scientists, Hisashi Hayakawa of Nagoya University, Koji Murata of the University of Tsukuba, and Mitsuru Sôma of the National Astronomical Observatory of Japan, have now pored through historical documents from and of the Byzantine Empire to do the same thing. This is to fill in a significant gap: from the fourth to the seventh centuries CE, there is a scarcity of solar eclipse records. It’s fiddly work. Often details that are pertinent to modern studies have not been included in the records, for instance. But the researchers were able to pinpoint five solar eclipses from records that hadn’t previously been analyzed. “Although original eyewitness accounts from this period have mostly been lost, quotations, translations, etc., recorded by later generations provide valuable information,” Murata says. “In addition to reliable location and timing information, we needed confirmation of eclipse totality: daytime darkness to the extent that stars appeared in the sky. We were able to identify the probable times and locations of five total solar eclipses from the 4th to 7th centuries in the Eastern Mediterranean region, in 346, 418, 484, 601, and 693 CE.” Largely, the values for ΔT that the team was able to derive from these results were consistent with previous estimates. However, there were some surprises. From the account of the eclipse that took place on July 19, 418 CE, the researchers identified the site of observation for the eclipse totality as Constantinople. The author, historian Philostorgius, describes the eclipse: “When Theodosius [Emperor Theodosius II] had reached adolescence, on the nineteenth of July at about the eighth hour, the Sun was so completely eclipsed that stars appeared.” Philostorgius lived in Constantinople from around 394 CE until his death, in around 439 CE. It is therefore most likely that he viewed the solar eclipse from there. The previous model for ΔT for this time would have placed Constantinople outside the path of eclipse totality – so the record has allowed the team to adjust ΔT for this time. The other records show slight adjustments too. “Our new ΔTdata fill a considerable gap and indicate that the ΔTmargin for the 5th century should be revised upward, whereas those for the 6th and 7th centuries should be revised downward,” Murata says. Although the tweaks may seem slight, they have considerable implications. They place tighter constraints on the variability of Earth’s rotation on century timescales, and may inform future studies of other geophysical phenomena, such as modeling the planetary interior, and long-term sea level changes. The research has been published in Publications of the Astronomical Society of the Pacific. Activist investor Dan Loeb’s Third Point LLC has bought a new stake in Walt Disney Co. DIS 2.57% and is calling on the media company to buy the rest of Hulu, explore spinning off ESPN and refresh its board. Mr. Loeb on Monday said his firm, which liquidated a large Disney stake earlier this year, has repurchased a “significant stake” in the company and sent a letter to Disney Chief Executive Bob Chapek urging the company to engage with Third Point on a number of issues. Mr. Loeb praised growth in Disney’s streaming subscriber base, but also wanted Disney to more aggressively cut costs and consider a number of steps to shake up its portfolio. The investor’s calls come at an inflection point for Disney and the streaming industry at large, which enjoyed torrential growth during Covid-19 but now face headwinds that include financial losses, domestic subscriber saturation and the introduction of new ad-supported tiers. Mr. Loeb also now represents a fresh challenge for Mr. Chapek, who assumed the CEO job in February 2020, one month before Covid-19 shut down his company’s theme parks and the nation’s movie theaters. Earlier this year, Mr. Chapek found himself under fire from his own employees and Florida Gov. Ron DeSantis over his response to the state’s bill known by opponents as the “Don’t Say Gay” legislation. Mr. Chapek was renewed to a three-year contract this summer, and recent subscriber growth in Disney’s flagship service, Disney+, has shown the company is advancing on the streaming industry’s dominant player, Netflix Inc. A spinoff of ESPN—itself a source of paying subscribers through its ESPN+ offering—would radically alter Disney’s presence in the streaming ecosystem. “We welcome the views of all our investors,” Disney said in response to Third Point’s letter. The company said its board has been continuously refreshed, “with an average tenure of four years.” Third Point is pushing Disney to “make every attempt” to buy up Comcast Corp.’s CMCSA 1.26% remaining minority stake in the streaming giant Hulu before its contractual deadline in early 2024. Under a 2019 agreement, Comcast can require Disney to purchase its NBCUniversal subsidiary’s one-third stake in Hulu by that deadline for at least $9 billion, assuming the streaming service has an equity value greater than $27.5 billion. “We believe that it would even be prudent for Disney to pay a modest premium to accelerate the integration but are cognizant that the seller may have an unreasonable price expectation at this time,” Mr. Loeb’s letter says. Disney and Comcast have been in a dispute over the value of Hulu, The Wall Street Journal previously reported. When Disney took majority control of Hulu in 2019, the service was valued at a minimum of $27.5 billion. Comcast believes the value of Hulu is now closer to $70 billion, people familiar with the matter have said. The two companies have already started to unwind some aspects of their partnership. Comcast’s NBCUniversal earlier this year exercised an option to exit its content-sharing agreement with Disney, the Journal reported. Content from NBCUniversal that previously would have gone to Hulu after airing on NBC and NBC-owned cable channels will now go directly to Peacock, NBCU’s streaming service. Mr. Loeb’s letter also states that there is a “strong case to be made” that Disney should spin off its ESPN business to shareholders to alleviate leverage at the parent company, despite ESPN’s centrality to the company’s streaming offerings and the significant free cash flow it generates. Mr. Loeb suggests that synergies between Disney and ESPN could be replicated through contractual arrangements. A spinoff would drive better long-term value for Disney shareholders and result in a business “no longer haunted by the specter of cord-cutting,” the letter says. Cord-cutting has driven Disney to make drastic changes to its business model in the past. In the summer of 2015, former Disney CEO Robert Iger acknowledged that the company was seeing “some subscriber losses” to ESPN. One year later, ESPN lost two million subscribers, dropping to its lowest count since 2005. That steady decline became an albatross on Disney’s stock price, which fell as investors feared a future in which ESPN—once a top moneymaker—fell in relevance and revenue. ESPN’s troubles—and Wall Street’s response to them—were one reason Mr. Iger would decide to launch his own streaming service. Disney+ premiered in the fall of 2019, and its rocketing growth in its first 18 months caused Disney shares to rise even as Covid-19 wrecked other parts of the business. Hollywood has been rampant with rumors about the future of ESPN since those first indications of subscriber losses, with rivals speculating that a spinoff or sale was in its future. Today, the sports network is one of three core components of Disney’s streaming bundle, along with Disney+ and Hulu. Disney+ has 152.1 million subscribers as of the most recent quarter, ESPN+ has 22.8 million and Hulu has 46.2 million. Mr. Loeb’s letter also urges the company to rethink the makeup of its board and consider a list of potential new members that Third Point has compiled. It also advocates for a wide-ranging cost-cutting program and the continuation of Disney’s pandemic-era suspension of cash dividend payments. Mr. Loeb has been a thorn in the side of studio chiefs before. In 2013, he bought a stake in Sony Group Corp. and publicly criticized the company’s movie arm, Sony Pictures Entertainment. He called on the company to make cuts to the division and introduce “discipline and accountability.” Soon after Mr. Loeb’s disclosure of a 7% stake, Sony Pictures’ then-CEO pledged to find at least $350 million in annual savings. Mr. Loeb sold his stake about a year later, but has called on Sony to make changes to its entertainment division in the years since. Last week, Disney reported better-than-expected earnings and added 14.4 million new subscribers to its Disney+ streaming service, many of which came to the service amid its expansion internationally. The company’s new customer additions brought its total at all of its streaming services, including Disney+, Hulu and ESPN+, to 221.1 million subscribers, which puts Disney’s streaming total narrowly ahead of rival Netflix Inc., which last month reported it had 220.67 million subscribers. Disney’s share price is up more than 12% in the past week, but remains down about 20% since the start of the year, amid a broad pullback in technology and media stocks. Last week, Disney also announced price increases to its streaming services, including for its planned ad-supported tier of Disney+, a move that industry executives and analysts said is intended to help drive profitability at its streamers. Disney, whose direct-to-consumer segment has lost more than $7 billion since Disney+ launched in late 2019, predicts that Disney+ will achieve profitability by September 2024. “We have plenty of room on price value,” Mr. Chapek said last week. Third Point previously held 4.1 million shares of Disney and successfully pushed the company to suspend its $3 billion annual dividend and plow the funds instead into the streaming business. But by the first quarter of this year, the hedge fund had completely exited its position. Mr. Loeb had become worried that it would take years for Disney’s streaming business to reap the profits needed to boost the company’s share price, a person familiar with his thinking told The Wall Street Journal in May. Write to Dean Seal at dean.seal@wsj.com and Erich Schwartzel at erich.schwartzel@wsj.com Copyright ©2022 Dow Jones & Company, Inc. All Rights Reserved. 87990cbe856818d5eddac44c7b1cdeb8 Over the last couple of years, has felt more nebulous than ever. You’d be forgiven for thinking that days are passing by at an increasingly faster clip. According to scientists, that perspective is not wrong. On June 29th, midnight arrived 1.59 milliseconds sooner than expected. It was the shortest day in over half a century, at least since scientists started tracking the pace of the Earth’s rotation with in the 1960s. That wasn’t a one-off occurrence either. In 2020, the planet saw what were, at the time, the 28 shortest days in recorded history. And just last week, on July 26th, the day lasted 1.5 milliseconds less than usual. “Since 2016 the Earth started to accelerate,” Leonid Zotov, a researcher at Lomonosov Moscow State University, told . “This year it rotates quicker than in 2021 and 2020.”
Days have become much longer since the Earth’s formation. As notes, around 1.4 billion years ago, a rotation of the Earth took less than 19 hours. Days have gotten longer by, on average, around one 74,000th of a second each year. But the planet’s rotation can fluctuate on a day-to-day basis. Scientists believe there are a number of factors that may impact the Earth’s rotation, including earthquakes, stronger winds , icecaps melting and refreezing, the moon and the climate. Some have suggested the so-called “Chandler wobble” may have an effect on the rotation too. That phenomenon is a “small, irregular deviation in the Earth’s points of rotation relative to the solid Earth,” as puts it. To account for fluctuations in the lengths of days, since 1972, there have been occasional leap seconds — a single-second addition to Coordinated Universal Time. Should the current trend of shorter days continue, there’s a possibility that a negative leap second may be needed to keep clocks aligned with the planet’s rotation. As such, UTC would skip a second. Leap seconds already cause havoc on ultra-precise systems. Just last week, , which have caused outages at Reddit and Cloudflare over the last decade. A negative leap second could lead to even more chaos. “With the Earth’s rotation pattern changing, it’s very likely that we will get a negative leap second at some point in the future,” Meta engineers Oleg Obleukhov and Ahmad Byagowi . “The impact of a negative leap second has never been tested on a large scale; it could have a devastating effect on the software relying on timers or schedulers.” All products recommended by Engadget are selected by our editorial team, independent of our parent company. Some of our stories include affiliate links. If you buy something through one of these links, we may earn an affiliate commission. NEWYou can now listen to Fox News articles!
New Yorkers were largely split in their opinion of whether the U.S. economy is currently experiencing a recession, a contrast from left-leaning media outlets united in their belief that the country is not experiencing an economic downturn. “I don’t think we’re in a recession,” one New Yorker told Fox News Digital on Monday. “I think technically—some indicators might, people might say that. It doesn’t sound like we’re in a recession to me.” He went on to acknowledge rising prices, but said that the White House and the Fed are “doing their best,” and that the economy overall is doing pretty well, especially in comparison to other countries. Another woman that Fox News Digital spoke to near Times Square said it doesn’t feel like the country is currently experiencing a recession, though it did feel like it before the city reopened following stringent COVID restrictions. COLBERT SKEWERS MSNBC, CNN FOR REDEFINING RECESSION, CLAIMS THEY’RE NOT ‘QUALIFIED’ TO SPEAK ON ISSUE
A New Yorker told Fox News Digital she did not believe the country was currently experiencing a recession, and said things have gotten better since COVID restrictions were lifted. “I don’t feel like there’s a recession, you know they opened up—there’s a lot of jobs. We’re still in a pandemic, however I don’t feel like it’s a recession because people are working. They can go out,” she added. A man that spoke near Radio City Music Hall said some parts of the economy are feeling the pain a “little bit harder” than other sectors, but for many people in New York City it is “life as usual.” “The inflation hurts a bit. But, these things come and go. It’s a cycle. I think we’ll recover pretty nicely, and I’m optimistic. I don’t like to label things a recession just because the media is saying one thing or another—I think we’ll be fine,” he added. But a number of other New Yorkers were adamant that the country is in the midst of a recession, and in some cases knocked the media and politicians for concluding otherwise. RECESSION ‘WORD CHURN’ FROM DEMOCRATS IS NOT WORKING, WARNS WASHINGTON POST COLUMNIST
A New Yorker told Fox News Digital that the media and the White House are ‘changing the definition’ of a recession. “It is a recession,” said another New Yorker. “They’re trying to change the definition, right? So I think the definition is two quarters, and then it’s a recession. So it’s been two negative quarters for the GDP, and they’re still saying it’s not a recession.” He added the media is trying to ignore “the fact” that there is a recession, and that their opinion changes depending on whether a Democrat or a Republican is in office. Another New Yorker said she was not “super confident” in the current economy, saying rising costs in the city, especially with rent, are “out of control.” She also poured cold water on the idea that a strong labor market meant that a recession was not the correct definition. “The people in power definitely need to be doing better,” she concluded. PAUL KRUGMAN DECLARES US NOT IN A RECESSION, CLAIMS ‘NEGATIVITY BIAS’ IN MEDIA
This New Yorker said the U.S. is experiencing a recession, and cited the rising cost of ‘everything,’ especially rent, in New York City. The Washington Post, CNN, The New York Times and others embraced the White House definition of a recession last week after GDP numbers showed consecutive quarters of negative growth as the U.S. economy enters a recession, and pundits on CNN, MSNBC, CBS, ABC and elsewhere also played up the notion of “fears” of a recession, rather than acknowledging the U.S. was now, by definition, going through one. CLICK HERE TO GET THE FOX NEWS APP Other segments on CNN, CBS News, MSNBC, NBC News, and ABC News largely refrained from saying that the country is in a recession, pointing to job growth and consumer spending. 3M plans to spin off its $8.6 billion health care business, a move meant to sharpen its focus and boost profitability. While not a complete breakup like those proposed by industrial peers General Electric and Toshiba, the decision announced Tuesday will profoundly reshape Maplewood-based 3M and chart a new course for its yet-to-be-named health care spinoff. “It’s a great opportunity for both businesses,” chief executive Mike Roman told the Star Tribune. “Actively managing our portfolio really helps us complement the value we create with our innovation and the businesses that we build.” The health care business accounts for a quarter of 3M’s revenue. Products include bandages, regulated medical devices, oral care and health care IT. Once complete, the 3M health care spinoff will be the third-largest medical technology company in the state after Medtronic and Boston Scientific. The remaining company, which will keep the 3M name, last year posted $26.8 billion in sales across its other segments: safety and industrial, consumer, transportation and electronics. The company will have a 19.9% stake in the health care spin-off that it will sell off over time, company leaders said. Roman told employees today that, for the time being, little will change. 3M has more than 90,000 global employees and about 10,000 in Minnesota. “There were a lot of questions about next steps and how we go forward,” he said. “What happens to employees, the name of the business, the locations and the buildings for those businesses will be decided over the next 15 to 18 months.” At nearly $9 billion in revenue, the spinoff would fall between Hormel and Polaris at No. 13 on the Star Tribune’s annual public company ranking — if it is headquartered in Minnesota. The separation is expected to be complete by the end of 2023. The move follows other industrial conglomerates, such as General Electric and Johnson & Johnson, that recently announced plans to break apart various segments into different companies. Many investors view such moves as a way to unlock a particular segment’s trapped value that might be buried beneath a corporation’s mountain of disparate priorities. Analysts largely lauded the 3M’s planned spinoff Tuesday, but questions remain over how the new businesses will fare. “This is a stable, low growth, profitable business,” Wolfe Research analyst Nigel Coe wrote about the health care business. He added the decision to spin it off “is some acknowledgement of the need for cash.” In recent weeks, 3M’s stock has been trading at its lowest levels in nearly a decade. Shares rose 5% Tuesday, closing at $140.82. “We have positioned health care to be successful as a stand-alone enterprise,” Roman told investors Tuesday morning. “Both companies will sharpen their focus to continue investing and winning in global end markets and have greater flexibility to strategically deploy capital, drive innovation, and accelerate growth.” The planned spinoff also comes less than three years after 3M grew its health care business with its largest ever acquisition, the $6.7 billion purchase of medical device company Acelity. For most of its 120-year history, 3M has focused on acquiring businesses — growing and evolving from an abrasives manufacturer to the major industrial supplier and consumer products maker it is today. But in recent years, 3M has been divesting more than acquiring. In addition to a still pending sale of its food safety business, 3M has offloaded 15 different businesses in the past decade, according to Mergr, a mergers and acquisitions database. One of the company’s largest spinoffs created Imation in 1996. After the spinoff, 3M will retain PFAS and earplug litigation liabilities, which are seen as a major drag on the company’s bottom line and stock. 3M saw sales and profitability slip across all of its divisions this spring compared to the year before. Revenue for the company’s second quarter, which ran April through June, totaled $8.7 billion. The company’s profit was almost entirely wiped out by Combat Arms and PFAS litigation costs. 3M earned a $2.2 billion profit before those and other expenses; the unadjusted quarterly profit was $78 million. On Tuesday, 3M announced plans to resolve the Combat Arms earplug litigation by sending its Aearo Technologies subsidiary through bankruptcy and setting $1 billion in a trust fund to pay claims. There are about 230,000 outstanding cases brought by U.S. military service members and veterans who allege the earplugs were faulty and caused hearing damage. Aearo filed for Chapter 11 bankruptcy protection on Tuesday. The company is also paying hundreds of millions of dollars to settle PFAS concerns in Belgium, though it faces ongoing litigation in the U.S. “We plan to vigorously defend ourselves,” Roman said. On Tuesday, 3M lowered its 2022 full-year financial outlook due to a strong U.S. dollar and the possibility of a recession. New research from Caltech proposes a new solution to a longstanding mystery about thin gas disks rotating around young stars. The key to solving a longstanding mystery about thin gas disks rotating around young stars: the motion of a tiny number of charged particles. This is according to a new study from the California Institute of Technology (Caltech). These rotating gas disks, called accretion disks, last tens of millions of years and are an early phase of solar system evolution. They contain a small fraction of the mass of the star around which they swirl; imagine a Astrophysicists recognized long ago that when this inward spiraling transpires, it should cause the radially inner part of the disk to spin increasingly faster, according to the law of the conservation of angular momentum. To understand the basic idea of the conservation of angular momentum, think of spinning figure skaters: when their arms are outstretched, they spin slowly, but as they draw their arms in, they spin faster and faster. The law of angular momentum conservation states that the angular momentum in a system stays constant, and angular momentum is proportional to velocity times radius. Therefore, if the skater’s radius decreases because they have pulled their arms in, then the only way to keep angular momentum constant is to increase the spin velocity. The inward spiral motion of the accretion disk is analogous to a skater drawing their arms in—and as such, the inner part of the accretion disk should spin faster. Astronomical observations do indeed show that the inner part of an accretion disk does spin faster. Curiously, however, it does not spin as fast as predicted by the law of conservation of angular momentum.
Collisions between neutral atoms and a much smaller number of charged particles may explain why the inner part of the solar system spin faster. Scientists have investigated many possible explanations for why accretion disk angular momentum is not conserved over the years. Some hypothesized that friction between the inner and outer rotating parts of the accretion disk might slow down the inner region. Calculations, however, demonstrate that accretion disks have very little internal friction. According to the dominant current hypothesis, magnetic fields cause a phenomenon known as a “magnetorotational instability” that results in the production of magnetic turbulence and gas—effectively forming friction that slows down the rotational speed of inward spiraling gas. “That concerned me,” says Paul Bellan, professor of applied physics at Caltech. “People always want to blame turbulence for phenomena they do not understand. There’s a big cottage industry right now arguing that turbulence accounts for getting rid of angular momentum in accretion disks.” A decade and a half ago, Bellan began investigating the question by analyzing the trajectories of individual atoms, electrons, and ions in the gas that constitutes an accretion disk. His goal was to determine how the individual particles in the gas behave when they collide with each other, as well as how they move in between collisions, to see if angular momentum loss could be explained without invoking turbulence.
As he explained over the years in a series of papers and lectures that were focused on “first principles”—the fundamental behavior of the constituent parts of accretion disks—charged particles (i.e., electrons and ions) are affected by both gravity and magnetic fields, whereas neutral atoms are only affected by gravity. This difference, he suspected, was key. Caltech graduate student Yang Zhang attended one of those talks after taking a course in which he learned how to create simulations of molecules as they collide with each other to produce the random distribution of velocities in ordinary gases, such as the air we breathe. “I approached Paul after the talk, we discussed it, and ultimately decided that the simulations might be extended to charged particles colliding with neutral particles in magnetic and gravitational fields,” Zhang says. Ultimately, Bellan and Zhang created a computer model of a spinning, super-thin, virtual accretion disk. The simulated disk contained around 40,000 neutral and about 1,000 charged particles that could collide with each other, and the model also factored in the effects of both gravity and a magnetic field. “This model had just the right amount of detail to capture all of the essential features,” Bellan says, “because it was large enough to behave just like trillions upon trillions of colliding neutral particles, electrons, and ions orbiting a star in a magnetic field.” The computer simulation showed collisions between neutral atoms and a much smaller number of charged particles would cause positively charged ions, or cations, to spiral inward toward the center of the disk, while negatively charged particles (electrons) spiral outward toward the edge. Neutral particles, meanwhile, lose angular momentum and, like the positively charged ions, spiral inward to the center.
A careful analysis of the underlying physics at the subatomic level—in particular, the interaction between charged particles and magnetic fields—shows that angular momentum is not conserved in the classical sense, though something called “canonical angular momentum” is indeed conserved. Canonical angular momentum is the sum of original ordinary angular momentum plus an additional quantity that depends on the charge on a particle and the magnetic field. For neutral particles, there is no difference between ordinary angular momentum and canonical angular momentum, so worrying about canonical angular momentum is unnecessarily complicated. But for charged particles—cations and electrons—the canonical angular momentum is very different from the ordinary angular momentum because the additional magnetic quantity is very large. Because electrons are negative and cations are positive, the inward motion of ions and outward motion of electrons, which are caused by collisions, increases the canonical angular momentum of both. Neutral particles lose angular momentum as a result of collisions with the charged particles and move inward, which balances out the increase in the charged-particle canonical angular momentum. It is a small distinction, but makes a huge difference on a solar system-wide scale, says Bellan, who argues that this subtle accounting satisfies the law of conservation of canonical angular momentum for the sum of all particles in the entire disk; only about one in a billion particles needs to be charged to explain the observed loss of angular momentum of the neutral particles.
Furthermore, Bellan says, the inward motion of cations and outward motion of electrons results in the disk becoming something like a gigantic battery with a positive terminal near the disk center and a negative terminal at the disk edge. Such a battery would drive electric currents that flow away from the disk both above and below the plane of the disk. These currents would power astrophysical jets that shoot out from the disk in both directions along the disk axis. Indeed, jets have been observed by astronomers for over a century and are known to be associated with accretion disks, though the force behind them has long been a mystery. Reference: “Neutral-charged-particle Collisions as the Mechanism for Accretion Disk Angular Momentum Transport” by Yang Zhang and Paul M. Bellan, 17 May 2022, Astrophysical Journal. Bellan and Yang’s paper was published in the Astrophysical Journal on May 17. Funding for this research came from the National Science Foundation. The motion of a tiny number of charged particles may solve a longstanding mystery about thin gas disks rotating around young stars, according to a new study from Caltech. These features, called accretion disks, last tens of millions of years and are an early phase of solar system evolution. They contain a small fraction of the mass of the star around which they swirl; imagine a Saturn-like ring as big as the solar system. They are called accretion disks because the gas in these disks spirals slowly inward toward the star. Scientists realized long ago that when this inward spiraling occurs, it should cause the radially inner part of the disk to spin faster, according to the law of the conservation of angular momentum. To understand conservation of angular momentum, think of spinning figure skaters: when their arms are outstretched, they spin slowly, but as they draw their arms in, they spin faster. Angular momentum is proportional to velocity times radius, and the law of angular momentum conservation states that the angular momentum in a system stays constant. So, if the skater’s radius decreases because they have drawn their arms in, then the only way to keep angular momentum constant is to increase the spin velocity.
The inward spiral motion of the accretion disk is akin to a skater drawing their arms in—and as such, the inner part of the accretion disk should spin faster. Indeed, astronomical observations show that the inner part of an accretion disk does spin faster. Curiously, though, it does not spin as fast as predicted by the law of conservation of angular momentum. Over the years, researchers have investigated many possible explanations for why accretion disk angular momentum is not conserved. Some thought friction between the inner and outer rotating parts of the accretion disk might slow down the inner region. However, calculations show that accretion disks have negligible internal friction. The leading current theory is that magnetic fields create what is called a “magnetorotational instability” that generates gas and magnetic turbulence—effectively forming friction that slows down the rotational speed of inward spiraling gas. “That concerned me,” says Paul Bellan, professor of applied physics. “People always want to blame turbulence for phenomena they do not understand. There’s a big cottage industry right now arguing that turbulence accounts for getting rid of angular momentum in accretion disks.” A decade and a half ago, Bellan began investigating the question by analyzing the trajectories of individual atoms, electrons, and ions in the gas that constitutes an accretion disk. His goal was to determine how the individual particles in the gas behave when they collide with each other, as well as how they move in between collisions, to see if angular momentum loss could be explained without invoking turbulence. As he explained over the years in a series of papers and lectures that were focused on “first principles”—the fundamental behavior of the constituent parts of accretion disks—charged particles (i.e., electrons and ions) are affected by both gravity and magnetic fields, whereas neutral atoms are only affected by gravity. This difference, he suspected, was key. Caltech graduate student Yang Zhang attended one of those talks after taking a course in which he learned how to create simulations of molecules as they collide with each other to produce the random distribution of velocities in ordinary gases, such as the air we breathe. “I approached Paul after the talk, we discussed it, and ultimately decided that the simulations might be extended to charged particles colliding with neutral particles in magnetic and gravitational fields,” Zhang says. Ultimately, Bellan and Zhang created a computer model of a spinning, super-thin, virtual accretion disk. The simulated disk contained around 40,000 neutral and about 1,000 charged particles that could collide with each other, and the model also factored in the effects of both gravity and a magnetic field. “This model had just the right amount of detail to capture all of the essential features,” Bellan says, “because it was large enough to behave just like trillions upon trillions of colliding neutral particles, electrons, and ions orbiting a star in a magnetic field.” The computer simulation showed collisions between neutral atoms and a much smaller number of charged particles would cause positively charged ions, or cations, to spiral inward toward the center of the disk, while negatively charged particles (electrons) spiral outward toward the edge. Neutral particles, meanwhile, lose angular momentum and, like the positively charged ions, spiral inward to the center. A careful analysis of the underlying physics at the subatomic level—in particular, the interaction between charged particles and magnetic fields—shows that angular momentum is not conserved in the classical sense, though something called “canonical angular momentum” is indeed conserved. Canonical angular momentum is the sum of original ordinary angular momentum plus an additional quantity that depends on the charge on a particle and the magnetic field. For neutral particles, there is no difference between ordinary angular momentum and canonical angular momentum, so worrying about canonical angular momentum is unnecessarily complicated. But for charged particles—cations and electrons—the canonical angular momentum is very different from the ordinary angular momentum because the additional magnetic quantity is very large. Because electrons are negative and cations are positive, the inward motion of ions and outward motion of electrons, which are caused by collisions, increases the canonical angular momentum of both. Neutral particles lose angular momentum as a result of collisions with the charged particles and move inward, which balances out the increase in the charged-particle canonical angular momentum. It is a small distinction, but makes a huge difference on a solar system-wide scale, says Bellan, who argues that this subtle accounting satisfies the law of conservation of canonical angular momentum for the sum of all particles in the entire disk; only about one in a billion particles needs to be charged to explain the observed loss of angular momentum of the neutral particles. Furthermore, Bellan says, the inward motion of cations and outward motion of electrons results in the disk becoming something like a gigantic battery with a positive terminal near the disk center and a negative terminal at the disk edge. Such a battery would drive electric currents that flow away from the disk both above and below the plane of the disk. These currents would power astrophysical jets that shoot out from the disk in both directions along the disk axis. Indeed, jets have been observed by astronomers for over a century and are known to be associated with accretion disks, though the force behind them has long been a mystery. Bellan and Yang’s paper was published in The Astrophysical Journal on May 17. Novel experiment validates widely speculated mechanism behind the formation of stars
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This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no When disordered magnetic materials are cooled to just the right temperature, something interesting happens. The spins of their atoms ‘freeze’ and lock into place in a static pattern, exhibiting cooperative behavior not usually displayed. Now for the first time, physicists have seen the opposite. When fractionally heated, the naturally occurring magnetic element neodymium freezes, turning all our expectations topsy turvy. “The magnetic behavior in neodymium that we observed is actually the opposite of what ‘normally’ happens,” said physicist Alexander Khajetoorians of Radboud University in the Netherlands. “It’s quite counterintuitive, like water that becomes an ice cube when it’s heated up.” In a conventional ferromagnetic material, such as iron, the magnetic spins of the atoms all align in the same direction; that is, their north and south magnetic poles are oriented the same way in three-dimensional space. But in some materials, such as some alloys of copper and iron, the spins are instead quite random. This state is what is known as a spin glass. You might be thinking “but neodymium is well known for making excellent magnets” and you’d be right… but it has to be mixed with iron in order for the spins to align. Pure neodymium doesn’t behave like other magnets; it was only two years ago that physicists determined this material is, in fact, best described as a self-induced spin glass. Now, it seems, neodymium is even stranger than we thought. When you heat a material, the rise in temperature increases the energy in that material. In the case of magnets, this increases the motion of the spins. But the opposite also occurs: When you cool down a magnet, the spins slow. For spin glasses, freezing temperature is the point at which the spin glass behaves more like a conventional ferromagnet. Led by physicist Benjamin Verlhac of Radboud University, a team of scientists wanted to probe how neodymium behaves under changing temperatures. Interestingly, they found that raising the temperature of neodymium from -268 degrees Celsius to -265 degrees Celsius (-450.4 to -445 Fahrenheit) induced the freeze state usually seen when cooling a spin glass. When the scientists cooled the neodymium back down, the spins once again fell into disarray. It’s unclear why this occurs, since it’s very rare that a natural material behaves in the ‘wrong’ way, contrary to how all the other materials of its kind behave. However, the scientists believe that it may have to do with a phenomenon called frustration. This is when a material is unable to attain an ordered state, resulting in a disordered ground state, such as we see in spin glasses. It’s possible, the researchers said, that neodymium has certain correlations in its spin glass state that are dependent on temperature. Raising the temperature weakens these, and also therefore the frustration, allowing the spins to settle into an alignment. Further investigation could reveal the mechanism behind this odd behavior in which order emerges from disorder with the addition of energy; the researchers note this has implications ranging far beyond physics. “This ‘freezing’ of the pattern does not normally occur in magnetic material,” Khajetoorians explained. “If we ultimately can model how these materials behave, this could also be extrapolated to the behavior of a wide range of other materials.” The research has been published in Nature Physics. Max Verstappen looked borderline untouchable throughout most of a sodden qualifying session at the British Grand Prix. But a spin from rival Charles Leclerc on the Monegasque’s final flying lap in Q3 saw Verstappen forced to settle for a philosophical P2, behind maiden pole-winner Carlos Sainz. No driver could get within four-tenths of Verstappen through the opening two segments of qualifying, the Dutchman in scintillating form after the heavens had opened at Silverstone 10 minutes ahead of the session start. But a spin from Verstappen on his first flying lap proven an ill portent, with provisional pole-sitter Verstappen then forced to lift off the throttle on his final lap when Leclerc spun in front on him – as Sainz came from nowhere to claim his maiden pole position, leaving Verstappen second. READ MORE: Sainz pips Verstappen to take maiden pole in wet British Grand Prix qualifying “I think it was a good qualifying,” said Verstappen. “The car was working really well, I felt comfortable. Just in Q3, it can be a little bit of a lottery, and I had a yellow flag on my final lap, so I had to back out of it a bit in the final corners, which at the end cost me pole. “But these things can happen. In the wet especially, everything needs to work well for you and it didn’t for me in the final lap. But overall our car is very good in dry and wet conditions so that’s also I think really important for tomorrow… Anything is possible for tomorrow.” Asked to comment on the first pole of his former Toro Rosso team mate Sainz, meanwhile, Verstappen replied generously: “It was good from Carlos, I think he had also a very solid qualifying. You can see it’s all the time very close between all of us up front, so we’re going to give it a good go and hopefully we can finish ahead.”
2022 British GP Qualifying: Verstappen’s dramatic save in the wet at Silverstone
Verstappen was backed up by Sergio Perez in P4, as Mercedes’ expected renaissance didn’t quite materialise, Lewis Hamilton P5 as George Russell took P8. But while Perez too was hindered by Leclerc’s spin, he was also confident for the race. “It wasn’t ideal, but on the other hand, it wasn’t too disappointing in a way towards the end,” said Perez. “I had Charles [spinning] right ahead of me, so my last two laps were not ideal, maybe there was a bit more in it, but P4, we can fight from there… and hopefully tomorrow in the race, we’re able to be a lot more competitive.” AS IT HAPPENED: All the action from qualifying for the British Grand Prix Red Bull team boss Christian Horner, meanwhile, revealed his shock that Verstappen had still managed to set a competitive time on the lap where he spun in Q3, saying: “He did a 180 and he only lost two seconds as he crossed the line, that was the ridiculous thing about it… It wasn’t part of the plan but Max likes to find the limit. It was just a shame he didn’t get that last lap but to still end up on the front row, after a tricky session like that, is a good place to be.” Red Bull now go in search of their first British Grand Prix win since Mark Webber’s triumph a decade ago – while Verstappen will look to emulate his 70th Anniversary Grand Prix Silverstone win from 2020.%2Fcdn.vox-cdn.com%2Fuploads%2Fchorus_asset%2Ffile%2F23464325%2Fbfarsace_160101_5219_0006.jpg&w=2400&q=75)
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Why Doesn’t the Inside of the Solar System Spin Faster?
DOI: 10.3847/1538-4357/ac62d5Why does inside of solar system not spin faster? Old mystery has possible new solution
Yang Zhang et al, Neutral-charged-particle Collisions as the Mechanism for Accretion Disk Angular Momentum Transport, The Astrophysical Journal (2022). DOI: 10.3847/1538-4357/ac62d5
California Institute of Technology
Why does inside of solar system not spin faster? Old mystery has possible new solution (2022, July 6)
retrieved 7 July 2022
from https://phys.org/news/2022-07-solar-faster-mystery-solution.html
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Physicists Are Startled by This Magnetic Material That ‘Freezes’ When Heated
Verstappen philosophical after Leclerc spin costs him shot at Silverstone pole
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