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  • richardmitnick 11:20 am on January 16, 2020 Permalink | Reply
    Tags: "Why is Puerto Rico Being Struck by Earthquakes?", , Discover Magazine, ,   

    From Discover Magazine: “Why is Puerto Rico Being Struck by Earthquakes?” 

    DiscoverMag

    From Discover Magazine

    January 7, 2020
    Erik Klemetti

    Multiple large earthquakes have hit Puerto Rico over the past week, all thanks to the geologically-active Caribbean Plate.

    The tectonic plates of the world were mapped in 1996, USGS.

    1
    Map of recent earthquakes from late December into early January 2020 near Puerto Rico. Credit: USGS.

    Since Monday, Puerto Rico has been struck by multiple magnitude 5 and 6 earthquakes. These earthquakes caused significant damage on an island still recovering from the devastation of Hurricane Maria in 2017.

    Most people don’t think of the Caribbean as an area rife for geologic activity, but earthquakes and eruptions are common. The major earthquakes in Puerto Rico and Haiti, as well as eruptions on Montserrat are all reminders that complex interactions between tectonic plates lie along the Caribbean Ocean’s margins.

    The Caribbean plate lies beneath much of the ocean of the same name (see below). It is bounded in the north and east by the North American plate, to the south by the South American plate and to the west by the Cocos plate. There isn’t much land mass above sea level on the plate beyond the islands that stretch from southern Cuba to the Lesser Antilles, along with parts of Central America like Costa Rica and Panama. A few small platelets have been identified along the margins of the plate as well.

    2
    Tectonic plates in the eastern Caribbean with historical earthquakes from 1900-2016 marked. Source: USGS.

    The northern edge of the plate is a transform boundary, where the two plates are sliding by each other. This causes stress that leads to earthquakes, much the same as the earthquakes generated along the San Andreas fault in California. This is why we’ve seen large earthquakes in places like Haiti, the Dominican Republic and now Puerto Rico.

    Head to the east and you reach the curving arc of islands that form the Lesser Antilles. Many of these islands are homes to potentially active volcanoes, such as Soufrière Hills on Montserrat, Pelée on Martinique, La Soufrière on St. Vincent and more. Other islands are homes to relict volcanoes as well. All these volcanoes have been formed by the North American plate sliding underneath the Caribbean, similar to the Cascade Range in the western United States and Canada.

    So, Puerto Rico doesn’t have active volcanoes, but it can experience large earthquakes. One of the most famous in the 1918 San Fermín earthquake that was a magnitude 7.1. Unlike the current temblors, the San Fermín earthquake occurred north of the island under the sea, generating a tsunami. More than 100 people likely died in that event.

    The current spate of earthquakes struck near the southern coast of the island. Both of the largest earthquakes — Monday’s M5.8 and Tuesday’s M6.4 — occurred during the early morning hours, when most people are at home. This heightens the risk of injuries and fatalities if homes collapse, but luckily so far the number of deaths is low. However, there has been significant damage to home and infrastructure already made precarious by the devastation of Hurricane Maria. This means longer-term hazards for the people of Puerto Rico.

    On top of this, the earthquakes have triggered landslides and rockfalls, increasing the threat to the island’s residents. The shaking also destroyed a picturesque natural bridge on the coast of the island. With dozens of aftershocks so far, it may be quite some time before people feel secure again.

    See the full article here .

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  • richardmitnick 12:38 pm on January 11, 2020 Permalink | Reply
    Tags: "Crater From Giant Meteorite Strike Might Be Hidden Under Volcanic Plateau", Although the evidence they present is thorough it’s not quite rock-solid., , Discover Magazine, Earth Observatory of Singapore, , New York Times, PNAS, , The first clue to the meteorite’s impact site came from the bits of glassy debris called tektites that it launched into the air about 800000 years ago., Ultimately a lava field in southern Laos turned up promising results.,   

    From smithsonian.com: “Crater From Giant Meteorite Strike Might Be Hidden Under Volcanic Plateau” 

    smithsonian
    From smithsonian.com

    January 10, 2020
    Theresa Machemer

    1
    A large meteorite can launch bits of molten rock into the atmosphere when it impacts Earth. When that molten rock cools, it forms tektites, shown here. (Photo by Robert Eastman / Alamy Stock Photo)

    Debris from the strike scattered across Earth, but the exact point of impact has been a mystery.

    The impact of a meteorite ranges from an Alabama woman’s giant bruise to the end of the dinosaurs. But one meteorite’s crater has eluded scientists for almost a century, despite the fact that it scattered glass confetti across one-tenth of the Earth’s surface. Now, experts at the Earth Observatory of Singapore have released a study, published in the Proceedings of the National Academy of Sciences, providing new evidence for the crater’s location.

    The first clue to the meteorite’s impact site came from the bits of glassy debris, called tektites, that it launched into the air about 800,000 years ago. The tektites landed across Antarctica, Australia and Asia, so geologist Kerry Sieh searched for signs of the crater in satellite imagery. Sieh’s search has taken years and led him down many dead-ends, Katherine Kornei reports for the New York Times-Hints of Phantom Crater Found Under Volcanic Plateau in Laos, but ultimately a lava field in southern Laos turned up promising results. There, volcanic eruptions long ago covered the land in molten rock, building a layer of igneous rock up to 1,000 feet deep, which could have easily obscured the impact crater.

    The research team began by analyzing previously published chemical characteristics of tektites found in Australia and Asia, and found evidence linking them to the Laotian lava field. They then estimated the age of the tektites and lava flows—the lava at the suspect site was younger than the lava around it—and measured the local gravitational field of the lava bed. Craters are often filled with less dense material that was broken apart on impact, and Sieh’s findings of a weaker gravitational pull provide more evidence of the impact crater’s existence.

    “There have been many, many attempts to find the impact site,” Sieh tells CNN’s Michelle Lim [A huge meteorite smashed into Earth nearly 800,000 years ago. We may have finally found the crater]. “But our study is the first to put together so many lines of evidence, ranging from the chemical nature of the tektites to their physical characteristics, and from gravity measurements to measurements of the age of lavas that could bury the crater.”

    By the new study’s calculations, the meteorite was about 1.2 miles wide and created a crater 8 miles wide and 11 miles long. It would have struck our planet at a speed fast enough to melt the Earth beneath it, material that was thrown into the air to create tektites. The impact also would have sent boulders flying at 1,500 feet per second, Leslie Nemo writes for Discover [Found: Crater From Asteroid Impact That Covered 10% of Earth’s Surface in Debris], some of which Sieh spotted in a hill that was cut through by a road a few miles away from the suspected impact site.

    Although the evidence they present is thorough, it’s not quite rock-solid. In a commentary [PNAS] that accompanied the study, impact crater expert Henry Melosh writes that Sieh and his team “present the best candidate yet for the long-sought source crater,” but adds, “one of my impact-savvy colleagues read the paper and was unconvinced. As with all possible impact craters, proof will rest on finding shock-metamorphosed rocks, minerals, and melt.”

    Melosh points out that the crater is smaller than previously expected for this meteorite, and that it would have had to land at an unusually shallow angle to create the oval shape that Sieh’s team proposes. To provide the strongest evidence that this is the crater they’ve been looking for, scientists would have to drill through the lava flows, which are in a tropical jungle, and recover rock samples from below.

    Sieh tells Nemo that he would be supportive of anyone who wants to complete that work.

    See the full article here .

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    Smithsonian magazine and Smithsonian.com place a Smithsonian lens on the world, looking at the topics and subject matters researched, studied and exhibited by the Smithsonian Institution — science, history, art, popular culture and innovation — and chronicling them every day for our diverse readership.

     
  • richardmitnick 1:27 pm on December 28, 2019 Permalink | Reply
    Tags: Discover Magazine,   

    From Discover Magazine: “Quantum Computers Finally Beat Supercomputers in 2019” 

    DiscoverMag

    From Discover Magazine

    December 28, 2019
    Stephen Ornes

    1
    LSU physicist Jonathan Dowling (right), shown with alumnus Todd Moulder, has pushed the growth rate in quantum computing. (Credit: LSU)

    In his 2013 book, Schrödinger’s Killer App, Louisiana State University theoretical physicist Jonathan Dowling predicted what he called “super exponential growth.” He was right. Back in May, during Google’s Quantum Spring Symposium, computer engineer Hartmut Neven reported the company’s quantum computing chip had been gaining power at breakneck speed.

    2
    Google’s Sycamore chip is kept cool inside their quantum cryostat.
    (Image: © Eric Lucero/Google, Inc.)

    The subtext: We are venturing into an age of quantum supremacy — the point at which quantum computers outperform the best classical supercomputers in solving a well-defined problem.

    Engineers test the accuracy of quantum computing chips by using them to solve a problem, and then verifying the work with a classical machine. But in early 2019, that process became problematic, reported Neven, who runs Google’s Quantum Artificial Intelligence Lab. Google’s quantum chip was improving so quickly that his group had to commandeer increasingly large computers — and then clusters of computers — to check its work. It’s become clear that eventually, they’ll run out of machines.

    Case in point: Google announced in October that its 53-qubit quantum processor had needed only 200 seconds to complete a problem that would have required 10,000 years on a supercomputer.

    Neven’s group observed a “double exponential” growth rate in the chip’s computing power over a few months. Plain old exponential growth is already really fast: It means that from one step to the next, the value of something multiplies. Bacterial growth can be exponential if the number of organisms doubles during an observed time interval. So can computing power of classical computers under Moore’s Law, the idea that it doubles roughly every year or two. But under double exponential growth, the exponents have exponents. That makes a world of difference: Instead of a progression from 2 to 4 to 8 to 16 to 32 bacteria, for example, a double-exponentially growing colony in the same time would grow from 2 to 4 to 16 to 256 to 65,536.

    Neven credits the growth rate to two factors: the predicted way that quantum computers improve on the computational power of classical ones, and quick improvement of quantum chips themselves. Some began referring to this growth rate as “Neven’s Law.” Some theorists say such growth was unavoidable.

    We talked to Dowling (who suggests a more fitting moniker: the “Dowling-Neven Law”) about double exponential growth, his prediction and his underappreciated Beer Theory of Quantum Mechanics.

    Q: You saw double exponential growth on the horizon long before it showed up in a lab. How?

    A: Anytime there’s a new technology, if it is worthwhile, eventually it kicks into exponential growth in something. We see this with the internet, we saw this with classical computers. You eventually hit a point where all of the engineers figure out how to make this work, miniaturize it and then you suddenly run into exponential growth in terms of the hardware. If it doesn’t happen, that hardware falls off the face of the Earth as a nonviable technology.

    Q: So you weren’t surprised to see Google’s chip improving so quickly?

    A: I’m only surprised that it happened earlier than I expected. In my book, I said within the next 50 to 80 years. I guessed a little too conservatively.

    Q: You’re a theoretical physicist. Are you typically conservative in your predictions?

    People say I’m fracking nuts when I publish this stuff. I like to think that I’m the crazy guy that always makes the least conservative prediction. I thought this was far-out wacky stuff, and I was making the most outrageous prediction. That’s why it’s taking everybody by surprise. Nobody expected double exponential growth in processing power to happen this soon.

    Q: Given that quantum chips are getting so fast, can I buy my own quantum computer now?

    A: Most of the people think the quantum computer is a solved problem. That we can just wait, and Google will sell you one that can do whatever you want. But no. We’re in the [prototype] era. The number of qubits is doubling every six months, but the qubits are not perfect. They fail a lot and have imperfections and so forth. But Intel and Google and IBM aren’t going to wait for perfect qubits. The people who made the [first computers] didn’t say, “We’re going to stop making bigger computers until we figure out how to make perfect vacuum tubes.”

    Q: What’s the big deal about doing problems with quantum mechanics instead of classical physics?

    A: If you have 32 qubits, it’s like you have 232 parallel universes that are working on parts of your computation. Or like you have a parallel processor with 232 processors. But you only pay the electric bill in our universe.

    Q: Quantum mechanics gets really difficult, really fast. How do you deal with that?

    A: Everybody has their own interpretation of quantum mechanics. Mine is the Many Beers Interpretation of Quantum Mechanics. With no beer, quantum mechanics doesn’t make any sense. After one, two or three beers, it makes perfect sense. But once you get to six or 10, it doesn’t make any sense again. I’m on my first bottle, so I’m in the zone.

    See the full article here .

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  • richardmitnick 2:18 pm on December 10, 2019 Permalink | Reply
    Tags: "Scientists Find a Shipworm That Eats and Lives Inside Rocks", , , Discover Magazine, , Lithoredo abatanica   

    From Discover Magazine : “Scientists Find a Shipworm That Eats, and Lives Inside, Rocks” 

    DiscoverMag

    From Discover Magazine

    1
    Unlike any other shipworm known to science, Lithoredo abatanica chews through, leaving behind twisted tunnels. (Credit: Marvin A. Altamia and J. Reuben Shipway)

    Between a rock and a hard place? That’s just where Lithoredo likes it.

    Researchers found the new-to-science shipworm, a kind of clam, in the Abatan River on the Philippines’ Bohol Island. It was a stunning sight.

    “It is unlike any other shipworm, both in its appearance and its unusual habits, and this was apparent from the very first moment I laid eyes on it,” says marine biologist Dan Distel, executive director of the Ocean Genome Legacy Center at Northeastern University and senior author of the June paper describing the animal in the journal Proceedings of the Royal Society B.

    Shipworms got their name because they bore through wood that’s in contact with water, eating the material. They leave behind tunnels lined with the calcium carbonate that they secrete, similar to the way their clam kin build shells. Shipworms have been a maritime plague for millennia, destroying boats and piers. But Lithoredo abatanica nibbled its way down a different evolutionary path. This shipworm eats rock.

    2
    Individuals such as this 4-inch-long specimen secrete calcium carbonate that hardens into a burrow lining. (Credit: Marvin A. Altamia and J. Reuben Shipway)

    Distel’s field colleagues, acting on a tip from an earlier French expedition about shipworms apparently boring into the Abatan River’s bedrock, had to strap on snorkeling gear to search for the animals.

    “[We] picked up these rocks, swam them over to the bank and proceeded to crack [them] open with a hammer and chisel,” says Reuben Shipway, the paper’s lead author and a marine biologist at the University of Portsmouth. “Splitting the rock open to reveal several shipworms inside was just so bizarre.”

    Specimens of Lithoredo range from less than an inch to more than a foot long. Perhaps not surprisingly, given its unique diet, the animal lacks the sharp, wood-chewing pseudo-teeth of all its relatives and instead has broad, spatula-like chompers.

    2
    Holes in a piece of limestone made by the new species of shipworm. (Credit: Marvin A. Altamia and J. Reuben Shipway)

    Finding the rock-eating shipworm raises a broader issue. Because the shell-like burrow linings of shipworms can survive in the fossil record long after the wood around them is gone, these tube-like structures have been used by researchers as a proxy for the presence of woody material in ancient environments.

    Lithoredo’s dining preference for limestone means that scientists can no longer make such an assumption. The animals who left the linings behind might have just been rocking out.

    “I think people tend to assume that nearly everything is known about the diversity of life on our planet, but nothing could be further from the truth,” says Distel. “The world is full of amazing creatures that have yet to be discovered, creatures that are stranger than fiction.”

    See the full article here.

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  • richardmitnick 5:59 pm on November 30, 2019 Permalink | Reply
    Tags: , , Black phosphorus, , , Chromium triiodide, Discover Magazine, , , Phosphorene, ,   

    From Discover Magazine: “Move over Graphene: Next-Gen 2D Materials Could Revolutionize Technology” 

    DiscoverMag

    From Discover Magazine

    November 29, 2019
    John Wenz

    Move over, flat carbon. Meet borophene, phosphorene and the rest of the next generation of “atomically thin” super-materials.

    1
    An illustration of graphene’s hexagonal molecular structure. (Credit: OliveTree/Shutterstock)

    The wonder material graphene — an array of interlinked carbon atoms arranged in a sheet just one atom thick — promised a world of applications, including super-fast electronics, ultra-sensitive sensors and incredibly durable materials. After a few false starts, that promise is close to realization. And a suite of other extremely thin substances is following in its wake.

    Graphene got its beginnings in 2003, when scientists at the University of Manchester found they could peel off a gossamer film of the material just by touching a piece of ordinary sticky tape to a block of purified graphite — the solid form of carbon that’s mixed with clay and used as the “lead” in most pencils. Graphene proved stronger than steel but extremely flexible, and electrons could zip through it at high speeds. It earned its discoverers the Nobel Prize in 2010, but researchers spent years struggling to manufacture it on larger scales and figuring out how its remarkable properties could best be used.

    They didn’t get it right straight out of the gate, says Todd Krauss, a chemist at the University of Rochester. “Scientists are pretty bad at predicting what’s going to be useful in applications,” he says.

    With its atom-thin sheets layered into tiny particles known as quantum dots, graphene was tried as a microscopic medical sensor, but it didn’t perform as desired, Krauss says. With its sheets rolled up into straw-like nanotubes, graphene was built into items like hockey sticks and baseball bats in the hopes that its strength and durability could better existing carbon fiber. But Krauss notes that there has since been a trend away from using nanotubes in consumer products. (Some also worry that long carbon nanotubes could harm the lungs since they have been shown to have some chemical resemblance to asbestos.)

    Today graphene is finding its way into different types of products. “Graphene is here,” says Mark Hersam of Northwestern University. Layered over zinc, graphene oxide is actively being developed as a replacement, with higher storage capacity, for the sometimes unreliable graphite now used in battery anodes. And nanotubes were recently used as transistors to build a microprocessor, replacing silicon (unlike flat graphene, nanotubes can be coaxed into acting like a semiconductor). Though the microprocessor was primitive by modern computing standards, akin to the processing level of a Sega Genesis, materials scientists think it could ultimately pave the way for more efficient, faster and smaller carbon components for computer processors.

    At the same time, a new generation of two-dimensional materials is emerging. The success of graphene further fueled the ongoing effort to find useful atomically thin materials, working with a range of different chemicals, so as to exploit the physical properties that emerge in such super-thin substances. The newcomers include an insulator more efficient than conventional ones at stopping the movement of electrons, and another that allows electrons to glide across it at a good percent of the speed of light, with little friction. Researchers think some of these may one day replace silicon in computer chips, among other potential uses.

    Other materials now in development have even higher aspirations, such as advancing scientists toward one of the most tantalizing goals in chemistry — the creation of high-temperature superconductors.

    Speedy Electrons

    In graphene, carbon atoms link up in an orderly honeycomb pattern, each atom sharing electrons with three neighboring carbon atoms. That structure allows any added electrons to move speedily across its surface. Ordinarily, a single electron might move through a conducting metal like copper at 1.2 inches per minute (given a 12-gauge wire with 10 amps of electricity). But in early experiments on graphene, electrons zipped along at 2.34 billion inches per minute — which could make for electronics that charge in just a few minutes and eventually in a matter of seconds.

    Graphene’s physical properties have inspired many potential applications, including in medicine. A variant of graphene, graphene oxide, is being studied as an experimental drug delivery vehicle. Seen here through a microscope, this chunk of graphene oxide is about 80 nanometers high. A single sheet of graphene is just 0.34 nanometers thick.

    Graphene conducts heat just as well as it conducts electricity. It’s also one of the strongest materials ever studied — stronger than steel, it can stop a bullet — but oddly stretchy too, meaning it’s both flexible and tough.

    Other 2D materials under exploration may have similar attributes as well as novel qualities all their own, but chemical impurities have until recently kept them hidden, says Angela Hight Walker, a project leader at the National Institute of Standards and Technology in Gaithersburg, Maryland. “We’re now getting to the point where we can see the new physics that’s been covered up by poor sample quality,” she says.

    One of the newcomers is black phosphorus, explored by Hersam and his coauthor Vinod Sangwan in the 2018 Annual Review of Physical Chemistry. When white phosphorus — a caustic, highly reactive chemical — is super-heated under high pressure, it becomes a flaky, conductive material with graphite-like behavior. Peeling off an atom-thin layer of this black phosphorus with sticky tape produces a material called phosphorene. First fabricated in 2014, phosphorene rivals graphene in terms of strength and ability to efficiently move electrons. But at the atomic level, it isn’t as perfectly flat as graphene — and that has intriguing consequences.

    Phosphorene interacts with electrons and photons in quirky ways, pointing to potential uses in future computer chips and fiber optics.

    In graphene, carbon atoms lie side by side, hence its flatness. But phosphorene’s 2D configuration looks a bit like a pleat, with two atoms at a lower level connected to two at a higher level, forming what’s called a bandgap. This wavy structure, in turn, affects the flow of electrons in a way that makes phosphorene a “semiconductor,” meaning that it’s very easy to switch the flow of electrons on or off. Phosphorene, like silicon, could find application in computer chips, where the toggled electrons represent 1s or 0s.

    Phosphorene also is especially good at emitting or absorbing photons at infrared wavelengths. This optical trick gives phosphorene huge potential for use in fiber-optic communication, Hersam says, because the bandgap matches the energy of infrared light near-exactly. It could also prove very useful in solar cells.

    Working with phosphorene is not easy, however. It is highly unstable and rapidly oxidizes unless stored correctly. “Literally, it will decompose if it is sitting out in the room,” Hight Walker says, typically in less than a minute. Layering it with other 2D materials could help protect the fragile chemical.

    Two Sides of Boron

    Boron would seem an odd fit for electronic applications. It’s better known as a fertilizer, an ingredient in fiberglass or (combined with salt) a laundry-detergent additive. But make it very thin and very flat, and boron begins to act more like a metal, conducting electricity easily. Two-dimensional boron, called borophene, is also ultra-flexible and transparent. Combined with its conductive properties, borophene’s flexibility and transparency could eventually make it a go-to material for new gadgets, including ultra-thin, foldable touch screens.

    Like graphene, borophene’s structure allows electrons to fly through it. It’s such a good conductor that it’s now being studied as a way to boost energy storage in lithium-ion batteries. Some researchers even think it might be coaxed into superconducting states at relatively high temperatures — though that’s still very cold (initial tests show the effect between minus-415 to minus-425 degrees Fahrenheit). Most current superconductors work close to absolute zero, or nearly minus -460 degrees F. A superconducting material allows electrons to move through it without any resistance, creating the potential for a device that accomplishes robust electronic feats while using only a small amount of power.

    3
    Emerging 2D materials phosphorene, borophene and boron nitride form thin films. Their atomic arrangements are viewed here from above and in profile. (Credit: Modified from V.K. Sangwan and M.C. Hersam/AR Physical Chemistry 2018)

    In the form of borophene, boron can conduct electrons like a metal. Yet, as part of a 2D-film of boron nitride, it can block the flow of electrons quite effectively. “In other words, 2D boron and [2D] boron nitride are on opposite ends of the electrical conductivity spectrum,” Hersam says.

    Boron nitride’s insulative property has come in handy for research on other 2D materials. Take that ephemeral black phosphorus: One way scientists have managed to keep it stable enough to study is by sandwiching it between two sheets of boron nitride.

    Even as it is blocking electrons, however, boron nitride will allow photons to pass, says physicist Milos Toth of the University of Technology Sydney, who coauthored an article about the potential of boron nitride, and other 2D materials, in the 2019 Annual Review of Physical Chemistry. That’s ideal for creating things called single-photon sources, which can emit a single particle of light at a time and are used in quantum computing, quantum information processing and physics experiments.

    Magnetic Material

    Another atomically thin material creating quite a buzz in materials science circles is a compound of chromium and iodine called chromium triiodide. It’s the first 2D material that naturally generates a magnetic field. Scientists working on chromium triiodide propose the material could eventually find uses in computer memory and storage, as well as in more research-focused purposes such as controlling how an electron spins.

    There’s a hitch, Hersam says: “This material is extremely hard to work with,” because it is both tough to synthesize and unstable once it’s made. Right now the only way to work with it is at extremely low temperatures, at minus-375 degrees Fahrenheit and below. But boron nitride might again come to the rescue: Some chromium triiodide samples have been preserved for months on end inside boron nitride sandwiches.

    Because of its finicky properties, chromium triiodide may not itself end up built into devices, Hight Walker says. “But when we understand the physics of what’s happening, we can go look for this 2D magnetic behavior in other materials.” A number of 2D magnetic materials are now being explored — single-layer manganese crystals woven into an insulating material is one possibility.

    Thin Sandwichesere

    Wrangling any of these thin layers into something usable may ultimately depend — literally — on how they stack up. Different super-thin materials would be layered together so that the properties inherent in each material can complement one another. “We have insulators, semiconductors, metals and now magnets,” Hight Walker says. “Those are the pieces that you need to make almost anything you want.”

    One potential application especially exciting to Hight Walker is in quantum computing. Unlike traditional computing, in which bits of information are either ones or zeroes, quantum computing allows each “qubit” of information to be both one and zero at once. In principle, this would allow quantum computers to quickly solve problems that would take an impossibly long time with conventional machines.

    Right now, though, most qubits are made of superconductors that have to be kept freezing cold, limiting their real-world use and motivating the search for new types of superconducting materials. For this reason, researchers are eager to explore borophene’s ability to superconduct. (Graphene, layered a certain way, also has shown potential superconducting properties.)

    But a stacked material involving several superconducting layers separated by strong insulators could enable smaller, more stable qubits that don’t require quite as low temperatures — which could reduce the overall size of quantum computers. Right now, these are room-sized affairs, much like early computers were. Reducing their size is going to require novel approaches and, possibly, very thin materials — layered sheet by little sheet.

    See the full article here .

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  • richardmitnick 4:57 pm on October 21, 2019 Permalink | Reply
    Tags: "Hubble Reveals New Evidence for Controversial Galaxies Without Dark Matter", , , , , Discover Magazine   

    From Discover Magazine: “Hubble Reveals New Evidence for Controversial Galaxies Without Dark Matter” 

    DiscoverMag

    From Discover Magazine

    October 21, 2019
    Jake Parks

    1
    This new and incredibly deep image from Hubble shows the dim and diffuse galaxy NGC 1052-DF4. New research presents the strongest evidence yet that this strange galaxy is basically devoid of dark matter. (Credit: NASA/ESA/STScI/S. Danieli et al.)

    Astronomers have all but confirmed the universe has at least one galaxy that’s woefully deficient in dark matter. The new finding not only indicates that galaxies really can exist without dark matter, but also raises fundamental questions about how such oddball galaxies form in the first place.

    The research, posted October 16 on the preprint site arXiv, used Hubble’s keen eye to take new, deep images of the ghostly galaxy NGC 1052-DF4 (or DF4 for short). Equipped with fresh observations, the researchers identified the bizarre galaxy’s brightest red giant stars (called the Tip of the Red Giant Branch, or TRGB). Because TRGB stars all shine with the same true brightness when viewed in infrared, the only thing that should affect how bright they appear is their distance.

    So, by identifying the galaxy’s TRGB and using that to determine DF4’s distance, the new data essentially confirms the galaxy is located some 61 million light-years away. And according to the researchers, this essentially debunks other studies that claim DF4 is much closer and therefore contains a normal amount of dark matter.

    “I think this is definitive,” co-author Pieter van Dokkum of Yale University told Astronomy via email.

    The Debate Over Galaxies Without Dark Matter

    Over the last few years, there’s been a controversy brewing in the astronomical community. In 2018, van Dokkum and his team stumbled upon a ghostly galaxy, nicknamed DF2, that seemed to lack any significant amount of dark matter [Nature]. And because dark matter is thought to account for about 85 percent of all matter in the universe, the apparent discovery of the first galaxy without the elusive substance raised a lot of eyebrows.

    One such skeptic was Ignacio Trujillo of the Instituto de Astrofisica de Canarias. Intrigued by the extraordinary claim of a galaxy without dark matter, Trujillo and his team quickly carried out their own analysis of DF2. Based on a variety of methods, Trujillo’s team determined that DF2 was actually much closer than van Dokkum’s team claimed — some 42 million light-years away rather than 61 million light-years. This, Trujillo argued in a 2019 study [MNRAS], meant that DF2 wasn’t as strange as initially thought, and instead hides about as much dark matter as you would expect from your average, run-of-the-mill galaxy.

    But then, just six days later, van Dokkum’s team published yet another study [The Astrophysical Journal Letters]identifying a second galaxy, named DF4, that was located about the same distance away as DF2 and likewise lacked dark matter. Yet again, Trujillo and his colleagues went about calculating their own distance to DF4. Based on the Hubble data available at the time, the non-dark-matter camp identified what they thought was DF4’s TRGB. But according to the newly presented Hubble data — which picked up many more, much fainters stars — Trujillo’s team may have misidentified the TRGB.

    “In the new data, there really is no ambiguity,” says study author Shany Danieli of Yale University. “We think the new data really rule out the [the closer distance derived by Trujillo’s group]. The TRGB is generally seen as definitive, as its physics is well understood.”

    What Does a Galaxy Without Dark Matter Mean?

    If these latest results hold up to the scrutiny that’s likely to come, then discovering the first (and possibly second) galaxy without dark matter would fundamentally change our understanding of how we think galaxies form and evolve.

    “[DF4 and DF2] point to an alternative channel for building galaxies — and they even raise the question whether we understand what a galaxy is,” van Dokkum says. Right now, he says, we think that galaxies begin with dark matter, which is how they’re able to gravitationally attract the massive amounts of gas and dust needed to kick-start star formation.

    “The thing is, we have no idea how star formation would proceed in the absence of dark matter,” van Dokkum says. “All we can say is that there must have been very dense gas early on in their history,” otherwise, the galaxies couldn’t create new stars.

    But is this latest distance determination to DF4 really robust enough to start exploring the implications of finding a galaxy without dark matter?

    “Yes, that’s our hope. We’d love to move to discuss what these galaxies mean, rather than whether our measurements were correct,” Danieli says.

    “That said,” she added, “we fully agree with everyone that ‘extraordinary claims require extraordinary evidence”‘

    See the full article here .

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  • richardmitnick 11:38 am on October 19, 2019 Permalink | Reply
    Tags: "Some Volcanoes Create Undersea Bubbles Up to a Quarter Mile Wide", , Discover Magazine,   

    From Discover Magazine: “Some Volcanoes Create Undersea Bubbles Up to a Quarter Mile Wide” 

    DiscoverMag

    From Discover Magazine

    October 18, 2019
    Meeri Kim

    1
    A plume of steam flows upward from Bogoslof volcano, a partially submerged volcano that created giant underwater bubbles when it erupted in 2017. (Credit: Dave Withrow, Alaska Volcano Observatory)

    As a geophysicist at the Alaska Volcano Observatory, John Lyons spends much of his days trying to decipher the music of volcanic eruptions. Sensitive microphones scattered across the Aleutian Arc — a chain of over 80 volcanoes that sweeps westward from the Alaskan peninsula — eavesdrop on every explosion, tremor and burp.

    In 2017, the partially submerged volcano Bogoslof erupted, sending clouds of ash and water vapor as high as 7 miles above sea level and significantly disrupting air traffic in the area. Throughout the nine months that the volcano remained active, the observatory’s microphones picked up a strange, low-and-slow melody that repeated over 250 times.

    “Instead of happening very fast and with high frequencies, which is typical for explosive eruptions, these signals were really low frequency, and some of them had periods up to 10 seconds,” said Lyons.

    The source of the odd sounds remained a mystery for months, until one of Lyons’ colleagues stumbled upon a striking description of the ocean’s surface during a 1908 Bogoslof eruption, observed from a Navy ship. As reported in a 1911 issue of The Technical World Magazine, officers reported seeing a “gigantic dome-like swelling, as large as the dome of the capitol at Washington [D.C.].” The dome shrank and grew until finally culminating in “great clouds of smoke and steam … gradually growing in immensity until the spellbound spectators began to fear they would be engulfed in a terrific cataclysm.”

    Lyons and his colleagues wondered if the low-frequency signals they heard could correspond to huge bubbles of gas forming just under the surface of the ocean. They modeled the sounds as overpressurized gas bubbles near the water-air interface, inspired by studies of magmatic bubbles that formed at the air-magma interface of Italy’s Stromboli volcano, which emitted similar signals but of shorter duration.

    Their results, published in the journal Nature Geoscience on Monday, suggest that submerged volcanic explosions can indeed produce Capitol dome-sized bubbles — and according to their calculations, these would be considered on the smaller side. The bubble diameters from the 2017 Bogoslof eruption were estimated to range from 100 to 440 meters (328 to 1,444 feet), with the largest stretching more than a quarter-mile across.

    “It’s hard to imagine a bubble so big, but the volumes of gas that we calculated to be inside the bubbles are similar to the volumes of gas that have been calculated for [open air] explosions,” said Lyons. “Take the big cloud of gas and ash that’s emitted from a volcano and imagine sticking that underwater. It has to come out somehow.”

    The researchers propose that gargantuan bubbles would arise from the unique interaction between cold seawater and hot volcanic matter. As magma begins to ascend from the submarine vent, the seawater rapidly chills the outer layer, producing a gas-tight cap over the vent. This rind of semicooled lava eventually pops like a champagne cork as a result of the pressure in the vent, releasing the gases trapped underneath as a large bubble. The bubble in the water grows larger and eventually pokes out into the air. After a few rounds of expansion and contraction, the bubble breaks, releasing the gas and producing eruption clouds in the atmosphere.

    The low-frequency sounds come from the bubble alternately growing and shrinking as it attempts to find an equilibrium between the expansion of the gas inside and the constriction of the shell, made up of mostly seawater and volcanic ash. The findings represent the first time such activity has been recorded with infrasound monitoring, which detects sound waves traveling in the air below the threshold of human hearing. Researchers are increasingly turning to the technique as a way to supplement traditional seismic data and gain more insight into eruption dynamics.

    “I find the work groundbreaking and impactful,” said Jeffrey B. Johnson, a geophysicist at Boise State University in Idaho who was not involved in the study. “Giant bubbles which defy the imagination are able to oscillate and produce sound that you can record several kilometers away.”

    Aside from the 1908 Bogoslof eruption, two other recorded observations match this phenomenon of giant bubbles emerging from the sea: the 1952-53 eruption of the Myojin volcano in Japan and the 1996 eruption of the Karymsky volcano in Russia. A report on the latter event describes “a rapidly rising, dark grey, smooth-surfaced bulbous mass of expanding gas and pyroclasts, probably maintained by surface tension within a shell of water.” The bubble grew to an estimated height of 450 meters above the sea surface.

    To witness these bubbles in real life is a challenge, since submerged volcanoes are often remote and surrounded by lots of ocean — not to mention, one’s timing has to be perfect. But Lyons hopes to follow up on this work by studying the dynamics of similar systems that are more approachable and directly observable, such as geysers or mud pots. He envisions listening in on the sounds coming from these types of bubbles to check the validity of certain assumptions they had to make in their model, such as the viscosity of the water.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

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  • richardmitnick 4:22 pm on October 14, 2019 Permalink | Reply
    Tags: "The Cosmos’ Most Powerful Magnets May Form When Stars Collide", AREPO simulation code, , , , Blue stragglers, , Discover Magazine   

    From Discover Magazine: “The Cosmos’ Most Powerful Magnets May Form When Stars Collide” 

    DiscoverMag

    From Discover Magazine

    October 14, 2019
    Jake Parks

    1
    These snapshots of two merging stars in action show the overall strength of the magnetic field in color (yellow is more magnetic), as well as the magnetic field lines (hatching). The stars on the left, which don’t have very strong magnetic fields, are just about to merge into a more massive and magnetic star (right). According to new research, such mergers can dramatically bolster the strength of the final star’s magnetic field. (Credit: F. Schneider et al./Nature volume 574, pages 211–214 (2019))

    More than 60 years ago, astronomers realized about 10 percent of massive stars have powerful magnetic fields bursting from their surfaces. But the exact origins of these magnetic fields —which can reach hundreds to thousands of times the strength of the Sun’s — has so far remained a mystery.

    The answer, it turns out, may be due to a collision between two normal stars.

    A team of scientists recently used cutting-edge simulations to uncover an evolutionary path they think explains the formation of extremely magnetic stars. And as a cherry on top, their findings may also shed light on the origins of a slew of other astronomical oddities. These mysteries include magnetars (a rare type of hyper-magnetic neutron star), blue stragglers (massive stars that appear too young for their age), and maybe even enigmatic cosmic events like fast radio bursts and super-luminous supernovae.

    The research was published October 9 in the journal Nature.

    Magnetic mergers

    When two stars collide, it sends their surfaces spinning and simultaneously kicks off enormous amounts of turbulence. This dramatically boosts the final star’s magnetic field.

    As the star spins, its inner layers rotate faster than its outer layers — a process called differential rotation. Running through and connecting each of these layers are magnetic field lines, Fabian Schneider of Heidelberg University and author of the new study told Astronomy. Because each layer rotates at a different speed, the magnetic field lines connecting the layers get twisted and tangled up, Schneider says. This serves to amplify the overall strength of the magnetic field.

    “Now comes the turbulence,” Schneider explained. During a merger event, stellar material gets violently sloshed around. This turbulence further stirs the magnetic field lines, exponentially increasing the star’s magnetism.

    But the new research doesn’t just describe how colliding stars can form insanely magnetized stars, it also may explain the origins of a bizarre class of strange objects called blue stragglers.

    3
    Blue straggler stars within the globular cluster M55 are circled in this color-magnitude diagram, which plots the color and overall brightness of stars of the same age. Middle-aged, main-sequence stars fall along the thick band spanning from the lower-right to the center of this image. When they evolve to red giants, they start climbing up the thin band to the upper-right. Rejuvenated blue stragglers are stars so massive (and therefore short-lived) that they seem like they should already be on the red giant branch, but they instead form their own extended population along the main sequence. (Credit: B.J. Mochejska, J. Kaluzny (CAMK), 1-m Swope Telescope)

    Carnegie Institution 1-meter Swope telescope at Las Campanas, Chile, 100 kilometres (62 mi) northeast of the city of La Serena. near the north end of a 7 km (4.3 mi) long mountain ridge. Cerro Las Campanas, near the southern end and over 2,500 m (8,200 ft) high, at Las Campanas, Chile

    [/caption]

    Making a blue straggler

    Blue stragglers are a unique class of stars that masquerade as stars younger than they truly are. These “rejuvenated” stars are much hotter — making them bluer — and brighter than your average main-sequence (or middle-aged) star of a similar apparent age.

    But what is the fountain of youth that keeps blue stragglers looking so fresh? A leading theory is that merging with another star will do the trick. And this new research supports that notion.

    First off, typical main-sequence stars power themselves by fusing hydrogen into helium in their cores. But when the hydrogen in their cores runs out, they move on to fusing concentric shells of hydrogen around their now-inert cores. This causes the star to balloon up into a red giant, moving it off the main-sequence and into the so-called red giant branch.

    But if two main-sequence stars collide, their material gets mixed together. The resulting merged product now has a restocked reservoir of hydrogen in its core, which allows it to chug along as a more massive — yet still main-sequence — blue straggler instead of evolving into a red giant.

    “This just means that post-merger stars have more nuclear fuel to then live longer,” Schneider says. “In other words, their internal clock has been set back.”

    But that only makes the newly formed star appear younger. “The point is simply that the blue straggler could have lived for a long time as lower-mass stars and then merged to become this more massive blue straggler,” Schneider says. “It’s high mass fooling us into thinking it must be younger.”

    Scientists first suggested a collision between two stars could generate strong magnetic fields more than a decade ago. “But until now, we weren’t able to test this hypothesis because we didn’t have the necessary computational tools,” said co-author Sebastian Ohlmann of the computing center at the Max Planck Society near Munich in a press release.

    But thanks to the powerful AREPO simulation code, the researchers were finally able to show that two merging stars, which originally lacked much magnetism, can join forces and create a new, highly magnetize star with a face lift.

    According to the study’s abstract, “This can explain the properties of the magnetic ‘blue straggler’ star τ Sco,” which is located less than 500 light-years away in the constellation Scorpius. Because τ Sco has an apparent age of less than five million years, while its birth cluster appears to be closer to 10 million years old, the researchers think the oddball star may be a prime example of what stellar mergers can produce.

    But that’s not all.

    The study’s abstract goes on to state: “Such massive blue straggler stars seem likely to be the progenitors of magnetars, perhaps giving rise to some of the enigmatic fast radio bursts observed, and their supernovae may be affected by their strong magnetic fields.”

    Magnetars are a rare breed of neutron stars with absurdly powerful magnetic fields that reach some 5 quadrillion (one quadrillion is 1,000 trillions) times stronger than Earth’s. “Magnetars are thought to have the strongest magnetic fields in the universe,” said co-author Friedrich Röpke of the Heidelberg Institute for Theoretical Studies in a press release.

    “We are suggesting that magnetars could be the natural end product of [main-sequence] and probably also pre-[main-sequence] mergers,” Schneider says. “The biggest and yet-unsolved question is whether the magnetic field produced in the merger can survive up to the supernova stage, and then whether the magnetic field is indeed maintained in the forming neutron star when the core of the star collapses.”

    “This still needs to be seen,” Schneider says, “but I think our suggestion is a very promising channel to finally understand the origin of magnetars and their strong magnetic fields.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

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  • richardmitnick 1:11 pm on October 10, 2019 Permalink | Reply
    Tags: "The Milky Way’s Supermassive Black Hole Erupted With a Violent Flare a Few Million Years Ago", , , , , Discover Magazine,   

    From Discover Magazine: “The Milky Way’s Supermassive Black Hole Erupted With a Violent Flare a Few Million Years Ago” 

    DiscoverMag

    From Discover Magazine

    October 9, 2019
    Erika K. Carlson

    1
    A flare erupted from the Milky Way’s center some 3.5 million years ago. While Earth wouldn’t be in any danger if it happened today, the light would be clearly visible. (Credit: James Josephides/ASTRO 3D)

    Astronomers believe supermassive black holes probably lurk in the centers of most large galaxies. These gargantuan black holes can gather swirling disks of material around them as their gravity attracts stars and gases. In some cases, these disks can emit vast amounts of light and even shoot huge jets of matter into space. The center of such an eventful galaxy is called an active galactic nucleus, or AGN.

    Our own Milky Way seems to have a relatively calm center, but astronomers suspect this wasn’t always the case.

    Some clues suggest that a flare of energetic radiation burst from our galaxy’s center within the last few million years. In a new study, a team of researchers now describe another piece of evidence that the Milky Way burped out such a flare, with the research also pointing to the supermassive black hole in our galaxy’s center, called Sagittarius A*, or Sgr A*, as being responsible.

    The team estimated this event occurred about 3.5 million years ago, give or take a million years. That would mean the Milky Way’s center transitioned from an active to a quiet phase pretty recently in Earth’s history, possibly when early human ancestors were roaming the planet.

    The flare would have been visible to the naked eye, shining about 10 times fainter than the full moon across a broad spectrum of light wavelengths.

    “It would look like the cone of light from a movie projector as it passes through a smoky theater,” University of Sydney astrophysicist and lead study author Jonathan Bland-Hawthorn said in an email.

    The researchers describe their findings in an upcoming paper in The Astrophysical Journal.

    Following the Trail

    Clues to the Milky Way’s active history include giant bubbles of gas ballooning out from the disk of the galaxy. The bubbles, which emit high-energy X-ray and gamma-ray radiation, could have formed when jets of matter shot out from the galaxy’s center.

    The new piece of evidence comes from examining a stream of gas that arcs around the Milky Way. This stream is like a trail that two dwarf galaxies, called the Large and Small Magellanic Clouds, leave as they orbit the Milky Way. The research team studied ultraviolet light coming from this gas trail, called the Magellanic Stream.

    The characteristics of the UV light indicate that gases in some sections of the stream are in an excited state. Only a very energetic event, like a beam of radiation from an active galactic nucleus, could have done this, according to Bland-Hawthorn. This means that our own home galaxy had an active galactic nucleus phase in the past.

    “I think AGN flickering is what goes on for all of cosmic time,” Bland-Hawthorn said via email. “All galaxies are doing this” — like volcanoes that can lie quietly for long stretches of time but suddenly erupt.

    Learning more about the central black hole of our galaxy is an exciting area of research, he added.

    “I think Sgr A* is the future of astrophysics, like searching for life signatures around planets,” Bland-Hawthorn said. “I am excited by what we will learn over the next 50 years.”

    See the full article here .

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  • richardmitnick 5:42 pm on September 11, 2019 Permalink | Reply
    Tags: "Giant Bubbles Spotted Rushing Out from Milky Way’s Center", , , , , Discover Magazine   

    From Discover Magazine: “Giant Bubbles Spotted Rushing Out from Milky Way’s Center” 

    DiscoverMag

    From Discover Magazine

    September 11, 2019
    Mara Johnson-Groh

    1
    The MeerKAT telescope is superimposed on a radio image of the Milky Way’s center. Radio bubbles extend from between the two nearest antennas to the upper right corner, with filaments running parallel to the bubbles. (Credit: South African Radio Astronomy Observatory/MeerKAT)

    The Milky Way is blowing bubbles. Two giant radio bubbles, extending out from the galaxy for over 1,400 light years, were just discovered in X-ray data. Astronomers think the bubbles started forming a few million years ago due to some type of cataclysmic event near the galaxy’s central supermassive black hole.

    The bubbles’ location also closely matches the range of over 100 narrow, magnetized filaments of radio emissions that stretch for tens of light years in length. First discovered 35 years ago, these filaments’ origins have remained a mystery, but the bubbles’ discovery may now provide an answer.

    “The filaments have been a mystery for a long time,” said Ian Heywood, astronomer at the University of Oxford and lead author on the new discovery. He says their results hint that the event that created the bubbles could have also produced high-energy charged particles that created the filaments.

    The symmetry of the bubbles billowing above and below the galaxy suggests they were formed by an extremely energetic explosion near the supermassive black hole at the center of the Milky Way. The most likely explanation is a flare up in the black hole’s activity as it gobbled up extra nearby material and burped out other particles and radiation. The bubbles could also have been created by an extreme burst in star formation that sent a shock wave across the galactic center. Or possibly, it was a combination of both events.

    The discovery, published on September 11 in the journal Nature, used the MeerKAT telescope, a radio telescope with 64 antennas, at the South African Radio Astronomy Observatory (SARAO) in South Africa.

    SKA SARAO Meerkat telescope(s), 90 km outside the small Northern Cape town of Carnarvon, SA

    Astronomers there were taking some of the first science images with the new telescope, looking at the radio emissions of the central galactic region, when they made the surprising discovery.

    “These enormous bubbles have until now been hidden by the glare of extremely bright radio emission from the center of the galaxy,” said Fernando Camilo of SARAO in Cape Town, and a co-author on the paper, in a press release.

    The astronomers were specifically looking at a type of radio emission called synchrotron radiation. This type or radiation is created when relativistic electrons — those traveling at nearly the speed of light — encounter strong magnetic fields, which imparts a particular signature on the light. Astronomers often use this type of radiation to pinpoint highly energetic regions in space.

    The new discovery isn’t the first giant bubble seen escaping from the Milky Way. In 2010, astronomers discovered two similar giant bubbles of gamma ray radiation blossoming above and below the galaxy, extending a combined length of 50,000 light-years. Now known as the Fermi bubbles, the origin of these balloons of radiation is still unexplained, but likely linked to the galaxy’s central supermassive black hole. The astronomers on this latest research think that the new radio bubbles they’ve discovered may have been caused by a smaller but similar event.

    “These fascinating radio bubbles provide a new window into understanding recent activity at the galactic center,” Andrew Fox, astronomer at the Space Telescope Science Institute, in Baltimore, Maryland, who was not involved with the new research, said via email. “Other observations taken across the electromagnetic spectrum have revealed evidence for a burst of activity several million years ago, and these new observations provide another clue. Taken together, the results show that the Milky Way blows bubbles on different scales.”

    By connecting the origin location of the bubbles to the central black hole region of the galaxy, astronomers are starting to learn more about the processes in this dynamic region. It may also help them learn about events unfolding in other galaxies. Evidence for giant gamma ray bubbles, like the Fermi bubbles, have also been seen outside the Milky Way in its nearest neighbor, the Andromeda galaxy.

    See the full article here .

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    Please help promote STEM in your local schools.

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