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  • richardmitnick 11:29 pm on March 1, 2017 Permalink | Reply
    Tags: , , , WIRED   

    From Wired: “Italy’s Etna Volcano Throws Lava Bombs in Its First Big Eruption of 2017” 

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    WIRED

    03.01.17
    Eric Clemetti

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    Europe’s biggest and most powerful volcano, Mount Etna, erupts sending an ash cloud across the holiday isle of Sicily.

    After one of the most quiet years in decades, Etna has decided to make 2017 a little more exciting. Early this week, the volcano had a moderate strombolian eruption, what the folks who monitor Etna call a “paroxysm,” that produced a lava fountain over the summit of the volcano. Strombolian eruptions (named after nearby Stromboli) are caused by gas-rich magma reaching the surface and erupting explosively. They also tend to produce lava flows at the same time, but they are less intense explosions than a plinian eruption (like what happened at Pinatubo or St. Helens).

    Some of the images of the eruption show a stream of lava coming from the New Southeast Crater while strombolian explosions threw lava bombs hundreds of meters from the vent. The ash from this eruption did not disrupt the air traffic in or out of the airport at nearby Catania—however, past stronger eruptions have caused it to shut down.

    Of course, there was a torrent of hyperbole published about this eruption. But even as dramatic as this eruption looked, it is relatively benign, mainly impacting the summit area of Etna. Always be skeptical of news articles that sell any volcanic eruption as a portend of doom or massive destruction.

    Very few actually are as hazardous as breathless media outlets would suggest. Eruptions at Etna may pose a hazard to air traffic through ash emissions, and slow-moving lava flows could endanger some of the villages and homes on the lower slopes of the volcano. This has happened before, and attempts were made to divert the lava flows (with moderate success). But the lava flow jeopardizes property much more than life; the flows move so slowly that you can likely out-walk them. Etna does have some history of explosive eruptions, but in its most recent activity over the last decade, these events have been very rare.

    Remember, there are a lot of webcams pointed at Etna. You can see a lot of different views (including IR thermal camera) on the INGV webcams, while Radio7 has a variety from different views and EtnaGuide has some near the summit. The next time Etna rumbles, be sure to check it out live.

    See the full article here .

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  • richardmitnick 2:36 pm on January 17, 2017 Permalink | Reply
    Tags: , , It's a bad time to be a physicist, Physicists run to Silicon Valley, , WIRED   

    From WIRED: “Move Over, Coders—Physicists Will Soon Rule Silicon Valley” 

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    Wired

    1
    Oscar Boykin.Ariel Zambelich/WIRED

    It’s a bad time to be a physicist.

    At least, that’s what Oscar Boykin says. He majored in physics at the Georgia Institute of Technology and in 2002 he finished a physics PhD at UCLA. But four years ago, physicists at the Large Hadron Collider in Switzerland discovered the Higgs boson, a subatomic particle first predicted in the 1960s. As Boykin points out, everyone expected it. The Higgs didn’t mess with the theoretical models of the universe. It didn’t change anything or give physcists anything new to strive for. “Physicists are excited when there’s something wrong with physics, and we’re in a situation now where there’s not a lot that’s wrong,” he says. “It’s a disheartening place for a physicist to be in.” Plus, the pay isn’t too good.

    Boykin is no longer a physicist. He’s a Silicon Valley software engineer. And it’s a very good time to be one of those.

    Boykin works at Stripe, a $9-billion startup that helps businesses accept payments online. He helps build and operate software systems that collect data from across the company’s services, and he works to predict the future of these services, including when, where, and how the fraudulent transactions will come. As a physicist, he’s ideally suited to the job, which requires both extreme math and abstract thought. And yet, unlike a physicist, he’s working in a field that now offers endless challenges and possibilities. Plus, the pay is great.

    If physics and software engineering were subatomic particles, Silicon Valley has turned into the place where the fields collide. Boykin works with three other physicists at Stripe. In December, when General Electric acquired the machine learning startup Wise.io, CEO Jeff Immelt boasted that he had just grabbed a company packed with physicists, most notably UC Berkeley astrophysicist Joshua Bloom. The open source machine learning software H20, used by 70,000 data scientists across the globe, was built with help from Swiss physicist Arno Candel, who once worked at the SLAC National Accelerator Laboratory. Vijay Narayanan, Microsoft’s head of data science, is an astrophysicist, and several other physicists work under him.

    It’s not on purpose, exactly. “We didn’t go into the physics kindergarten and steal a basket of children,” says Stripe president and co-founder John Collison. “It just happened.” And it’s happening across Silicon Valley. Because structurally and technologically, the things that just about every internet company needs to do are more and more suited to the skill set of a physicist.

    The Naturals

    Of course, physicists have played a role in computer technology since its earliest days, just as they’ve played a role in so many other fields. John Mauchly, who helped design the ENIAC, one of the earliest computers, was a physicist. Dennis Ritchie, the father of the C programming language, was too.

    But this is a particularly ripe moment for physicists in computer tech, thanks to the rise of machine learning, where machines learn tasks by analyzing vast amounts of data. This new wave of data science and AI is something that suits physicists right down to their socks.

    Among other things, the industry has embraced neural networks, software that aims to mimic the structure of the human brain. But these neural networks are really just math on an enormous scale, mostly linear algebra and probability theory. Computer scientists aren’t necessarily trained in these areas, but physicists are. “The only thing that is really new to physicists is learning how to optimize these neural networks, training them, but that’s relatively straightforward,” Boykin says. “One technique is called ‘Newton’s method.’ Newton the physicist, not some other Newton.”

    Chris Bishop, who heads Microsoft’s Cambridge research lab, felt the same way thirty years ago, when deep neural networks first started to show promise in the academic world. That’s what led him from physics into machine learning. “There is something very natural about a physicist going into machine learning,” he says, “more natural than a computer scientist.”

    The Challenge Space

    Ten years ago, Boykin says, so many of his old physics pals were moving into the financial world. That same flavor of mathematics was also enormously useful on Wall Street as a way of predicting where the markets would go. One key method was The Black-Scholes Equation, a means of determining the value of a financial derivative. But Black-Scholes helped foment the great crash of 2008, and now, Boykin and others physicists say that far more of their colleagues are moving into data science and other kinds of computer tech.

    Earlier this decade, physicists arrived at the top tech companies to help build so-called Big Data software, systems that juggle data across hundreds or even thousands of machines. At Twitter, Boykin helped build one called Summingbird, and three guys who met in the physics department at MIT built similar software at a startup called Cloudant. Physicists know how to handle data—at MIT, Cloudant’s founders handled massive datasets from the the Large Hadron Collider—and building these enormously complex systems requires its own breed of abstract thought. Then, once these systems were built, so many physicists have helped use the data they harnessed.

    In the early days of Google, one of the key people building the massively distributed systems in the company’s engine room was Yonatan Zunger, who has a PhD in string theory from Stanford. And when Kevin Scott joined the Google’s ads team, charged with grabbing data from across Google and using it to predict which ads were most likely to get the most clicks, he hired countless physicists. Unlike many computer scientists, they were suited to the very experimental nature of machine learning. “It was almost like lab science,” says Scott, now chief technology officer at LinkedIn.

    Now that Big Data software is commonplace—Stripe uses an open source version of what Boykin helped build at Twitter—it’s helping machine learning models drive predictions inside so many other companies. That provides physicists with any even wider avenue into the Silicon Valley. At Stripe, Boykin’s team also includes Roban Kramer (physics PhD, Columbia), Christian Anderson (physics master’s, Harvard), and Kelley Rivoire (physics bachelor’s, MIT). They come because they’re suited to the work. And they come because of the money. As Boykin says: “The salaries in tech are arguably absurd.” But they also come because there are so many hard problems to solve.

    Anderson left Harvard before getting his PhD because he came to view the field much as Boykin does—as an intellectual pursuit of diminishing returns. But that’s not the case on the internet. “Implicit in ‘the internet’ is the scope, the coverage of it,” Anderson says. “It makes opportunities much greater, but it also enriches the challenge space, the problem space. There is intellectual upside.”

    The Future

    Today, physicists are moving into Silicon Valley companies. But in the years come, a similar phenomenon will spread much further. Machine learning will change not only how the world analyzes data but how it builds software. Neural networks are already reinventing image recognition, speech recognition, machine translation, and the very nature of software interfaces. As Microsoft’s Chris Bishop says, software engineering is moving from handcrafted code based on logic to machine learning models based on probability and uncertainty. Companies like Google and Facebook are beginning to retrain their engineers in this new way of thinking. Eventually, the rest of the computing world will follow suit.

    In other words, all the physicists pushing into the realm of the Silicon Valley engineer is a sign of a much bigger change to come. Soon, all the Silicon Valley engineers will push into the realm of the physicist.

    See the full article here .

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  • richardmitnick 3:00 pm on January 2, 2017 Permalink | Reply
    Tags: , Deep Within a Mountain Physicists Race to Unearth Dark Matter, , WIRED, , Xenon Collaboration   

    From WIRED: Women in STEM- “Deep Within a Mountain, Physicists Race to Unearth Dark Matter” Elena Aprile 

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    WIRED

    01.01.17
    Joshua Sokol

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    Elena Aprile in her lab at Columbia University.Ben Sklar for Quanta Magazine

    In a lab buried under the Apennine Mountains of Italy, Elena Aprile, a professor of physics at Columbia University, is racing to unearth what would be one of the biggest discoveries in physics.

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    There is five times more dark matter in the Universe than “normal” matter, the atoms and molecules that make up all we know. Yet, it is still unknown what this dominant dark component actually is.

    Today, an international collaboration of scientists inaugurated the new XENON1T instrument designed to search for dark matter with unprecedented sensitivity, at the Gran Sasso Underground Laboratory of INFN in Italy.

    Gran Sasso LABORATORI NAZIONALI del GRAN SASSO
    Gran Sasso LABORATORI NAZIONALI del GRAN SASSO,located in the Abruzzo region of central Italy

    She has not yet succeeded, even after more than a decade of work. Then again, nobody else has, either.

    Aprile leads the XENON dark matter experiment, one of several competing efforts to detect a particle responsible for the astrophysical peculiarities that are collectively attributed to dark matter.

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    These include stars that rotate around the cores of galaxies as if pulled by invisible mass, excessive warping of space around large galaxy clusters, and the leopard-print pattern of hot and cold spots in the early universe.

    For decades, the most popular explanation for such phenomena was that dark matter is made of as-yet undiscovered weakly interacting massive particles, known as WIMPs. These WIMPs would only rarely leave an imprint on the more familiar everyday matter.

    That paradigm has recently been under fire. The Large Hadron Collider located at the CERN laboratory near Geneva has not yet found anything to support the existence of WIMPs. Other particles, less studied, could also do the trick. Dark matter’s astrophysical effects might even be caused by modifications of gravity, with no need for the missing stuff at all.

    The most stringent WIMP searches have been done using Aprile’s strategy: Pour plenty of liquid xenon—a noble element like helium or neon, but heavier—into a vat. Shield it from cosmic rays, which would inundate the detector with spurious signals. Then wait for a passing WIMP to bang into a xenon atom’s nucleus. Once it does, capture out the tiny flash of light that should result.

    These experiments use progressively larger tanks of liquid xenon that the researchers believe should be able to catch the occasional passing WIMP. Each successive search without a discovery shows that WIMPs, if they exist, must be lighter or less prone to leave a mark on normal matter than had been assumed.

    In recent years, Aprile’s team has vied with two close competitors for the title of Most-thorough WIMP Search: LUX, the Large Underground Xenon experiment, a U.S.-based group that split from her team in 2007, and PandaX, the Particle and Astrophysical Xenon experiment, a Chinese group that broke away in 2009. Both collaborators-turned-rivals also use liquid-xenon detectors and similar technology. Soon, though, Aprile expects her team to be firmly on top: The third-generation XENON experiment—larger than before, with three and a half metric tons of xenon to catch passing WIMPs—has been running since the spring, and is now taking data. A final upgrade is planned for the early 2020s.

    The game can’t go on forever, though. The scientists will eventually hit astrophysical bedrock: The experiments will become sensitive enough to pick up neutrinos from space, flooding the particle detectors with noise. If WIMPs haven’t been detected by that point, Aprile plans to stop and rethink where else to look.

    Aprile splits her time between her native Italy and New York City, where in 1986 she became the first female professor of physics at Columbia University. Quanta caught up with her on a Saturday morning in her Brooklyn high-rise apartment that faces toward the Statue of Liberty. An edited and condensed version of the interview follows.

    QUANTA MAGAZINE: How closely do you follow the theoretical back and forth about the nature of dark matter?

    ELENA APRILE: For me, driving the technology, driving the detector, making it the best detector is what makes it exciting. The point right now is that in a couple of years, maybe four or five in total, we will definitely say there is no WIMP or we will discover something.

    I don’t care much about what the theorists say. I go on with my experiment. The idea of the WIMP is clearly today still quite ideal. Nobody could tell you “No, you’re crazy looking for a WIMP.”

    What do you imagine will happen over the next few years in this search?

    If we find a signal, we have to go even faster and build a larger scale detector which we are planning already—in order to have a chance to see more of them, and have a chance to build up the statistics. If we see nothing after a year or two, the same story.

    The plan for the collaboration, for me and how I drive these 130 people, is very clear for the next four or five years. But beyond that, we will go almost to the level that we start really to see neutrinos. If we end up being lucky—if a supernova goes off next to us and we see neutrinos—we will not have found dark matter, but still detect something very exciting.

    How did you get started with this xenon detector technology?

    I started my career as a summer student at CERN. Carlo Rubbia was a professor at Harvard and also a physicist at CERN. He proposed a liquid-argon TPC—time projection chamber. This was hugely exciting as a detector because you can measure precisely the energy of a particle, and you can measure the location of the interaction, and you can do tracking. So, that was my first experience, to build the first liquid-argon ‘baby’ detector—1977, yes, that’s when it started. And then I went to Harvard, and I did my early work with Rubbia on liquid argon. That was the seed that led eventually to the monstrous, huge liquid-argon detector called ICARUS.

    Later, I left Rubbia and I accepted the position of assistant professor here at Columbia. I got interested in continuing with liquid-argon detectors, but for neutrino detection from submarines. I got my first grant from DARPA [the Defense Advanced Research Projects Agency]. They didn’t give a damn about supernova neutrinos, but they wanted to see neutrinos from the [nuclear] Russian submarines. And then we had Supernova 1987A, and I made a proposal to fly a liquid-argon telescope on a high-altitude balloon to detect the gamma rays from this supernova.

    I studied a lot—the properties of argon, krypton, xenon—and then it became clear that xenon is a much more promising material for gamma-ray detection. So I turned my attention to liquid xenon for gamma-ray astrophysics.

    How did that swerve into a search for dark matter?

    I had this idea that this detector I built for gamma-ray astrophysics could have been, in another version, ideal to look for dark matter. I said to myself: “Maybe it’s worth going into this field. The question is hot, and maybe we have the right tool to finally make some progress.”

    It’s atypical that the NSF [National Science Foundation], for someone new like me, will fund the proposal right away. It was the strength of what I had done all those years with the a liquid-xenon TPC for gamma-ray astrophysics. They realized that this woman can do it. Not because I’m very bold and I proposed a very aggressive program—which of course is typical of me—but I think it was the work that we did for another purpose which gave the strength to the XENON program, which I proposed in 2001 to the NSF.

    What was it like to go from launching high-altitude balloons to working underground?

    We had quite a few balloon campaigns. It’s something that I would do again, and I didn’t appreciate it then. You get your detector ready, you sit it on this gondola. At some point you are ready, but you can’t do anything because every morning you go and you wait for the weather guy to tell you if it’s the right moment to fly. In that scenario you are a slave to something bigger than you, which you can’t do anything about. You go on the launch pad, you look at the guy measuring, checking everything, and he says “No.”

    Underground, I guess, there is no such major thing holding you from operating your detector. But there are still, in the back of your mind, thoughts about the seismic resilience of what you designed and what you built.

    In a 2011 interview with The New York Times about women at the top of their scientific fields, you described the life of a scientist as tough, competitive and constantly exposed. You suggested that if one of your daughters aspired to be a scientist you would want her to be made of titanium. What did you mean by that?

    Maybe I shouldn’t demand this of every woman in science or physics. It’s true that it might not be fair to ask that everyone is made of titanium. But we must face it—in building or running this new experiment—there is going to be a lot of pressure sometimes. It’s on every student, every postdoc, every one of us: Try to go fast and get the results, and work day and night if you want to get there. You can go on medical leave or disability, but the WIMP is not waiting for you. Somebody else is going to get it, right? This is what I mean when I say you have to be strong.

    Going after something like this, it’s not a 9-to-5 job. I wouldn’t discourage anyone at the beginning to try. But then once you start, you cannot just pretend that this is just a normal job. This is not a normal job. It’s not a job. It’s a quest.

    In another interview, with the Italian newspaper La Repubblica, you discussed having a brilliant but demanding mentor in Carlo Rubbia, who won the Nobel Prize for Physics in 1984. What was that relationship like?

    It made me of titanium, probably. You have to imagine this 23-year-old young woman from Italy ending up at CERN as a summer student in the group of this guy. Even today, I would still be scared if I were that person. Carlo exudes confidence. I was just intimidated.

    He would keep pushing you beyond the state that is even possible: “It’s all about the science; it’s all about the goal. How the hell you get there I don’t care: If you’re not sleeping, if you’re not eating, if you don’t have time to sleep with your husband for a month, who cares? You have a baby to feed? Find some way.” Since I survived that period I knew that I was made a bit of titanium, let’s put it that way. I did learn to contain my tears. This is a person you don’t want to show weakness to.

    Now, 30 years after going off to start your own lab, how does the experience of having worked with him inform the scientist you are today, the leader of XENON?

    For a long time, he was still involved in his liquid-argon effort. He would still tell me, “What are you doing with xenon; you have to turn to argon.” It has taken me many years to get over this Rubbia fear, for many reasons, probably—even if I don’t admit it. But now I feel very strong. I can face him and say: “Hey, your liquid-argon detector isn’t working. Mine is working.”

    I decided I want to be a more practical person. Most guys are naive. All these guys are naive. A lot of things he did and does are exceptional, yes, but building a successful experiment is not something you do alone. This is a team effort and you must be able to work well with your team. Alone, I wouldn’t get anywhere. Everybody counts. It doesn’t matter that we build a beautiful machine: I don’t believe in machines. We are going to get this damn thing out of it. We’re going to get the most out of the thing that we built with our brains, with the brains of our students and postdocs who really look at this data. We want to respect each one of them.

    See the full article here .

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  • richardmitnick 12:02 pm on December 14, 2016 Permalink | Reply
    Tags: , Mount St. Helens, WIRED   

    From WIRED: “A Swarm of Earthquakes Shakes Mount St. Helens” 

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    Wired

    12.13.16
    Erik Klemetti

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    An aerial view of Mount St.Helens in Washington State from May 2009.Getty Images

    Mount St. Helens is keeping up its unsettled 2016, this time with another small earthquake swarm. The USGS detected over 120 earthquakes over the last few days, all occurring 2-4 kilometers (1-2 miles) beneath the volcano and all very small (less than M1). These earthquakes, like the ones that happened earlier this year, are likely caused by magma moving or faults adjusting as pressure changes within the magmatic system underneath Mount St. Helens. It doesn’t change the status of the volcano: It’s active, taking what will likely be a brief rest before its next eruption. That could still be years from now.

    See the full article here .

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  • richardmitnick 8:25 am on October 3, 2016 Permalink | Reply
    Tags: A New Generation of Astronomers Is on the Hunt for the Next Earth, ESPRESSO, EXPRES, WIRED   

    From WIRED: “A New Generation of Astronomers Is on the Hunt for the Next Earth” 

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    Wired

    10.03.16
    Sarah Scoles

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    An artist’s rendering of the planet Proxima b orbiting the red dwarf star Proxima Centauri.M. Kornmesser/ESO.

    About a month ago, astronomers announced they had found a new exoplanet—this one, orbiting in the habitable zone of the nearest star to Earth. Proxima b is exciting because it’s nearby, and someday someone might send a spaceprobe to it. Plus, it has a mass close to Earth’s—making it more likely to be livable.

    But Proxima b is also notable because scientists know its mass at all. Many of the 44 potentially habitable exoplanets have been found by Kepler-style transit searches, which watch and wait for planets to pass in front of stars and eclipse some of their light.

    Planet transit. NASA/Ames
    Planet transit. NASA/Ames

    But that only gives you a measure of a planet’s radius. Proxima b popped out of a different technique, one that, for the most part, hasn’t been sensitive enough to see planets like Earth. And advances in that technique—including a new instrument called EXPRES—could improve detection enough for scientists to find and weigh lots of other Earth-mass planets.

    That exoplanet-finding method, called a radial velocity search, works by detecting the seesaw of a star pulled around by its planet’s gravity. The back-and-forth movement in each orbit takes the star ever so slightly toward us, and then ever so slightly away from us. Rinse and repeat, at regular intervals. When the star moves in our direction, its light waves appear a little squished—bluer. When it moves away, the waves appear stretched—redder.

    Transits tell us a planet’s radius. Radial velocities tell us a planet’s mass. But a planet’s overall density, and so its composition, only comes from their powers combined. If scientists only knew how wide you were and not how much you weighed, they wouldn’t know if you were gassy or rocky. The same is true of planets. So being able to detect Earth-sized planets with the radial velocity method will help scientists to figure out if they actually are Earth-like. That’s an express goal of EXPRES, and the Yale lab led by astronomer Debra Fischer that is developing it.

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    EXPRES

    The Hardware

    EXPRES is a spectrograph, a device that can measure the regular, repeating shifts from radial velocity changes. They split incoming light up by wavelength—like a prism, if prisms provided lots of data. The previous state-of-the-astronomical-art, an instrument called HARPS, was installed on a 3.6-meter telescope in Chile by the University of Geneva in Switzerland in 2003. But HARPS doesn’t comb the star’s spectrum finely enough to see the littlest, lice-like planets. And it doesn’t take stars’ natural noise into account enough.

    ESO/HARPS
    “ESO/HARPS

    ESO 3.6m telescope & HARPS at LaSilla
    ESO 3.6m telescope & HARPS at LaSilla, Chile.

    “We’re used to the idea that the exoplanet research is this booming industry,” Fischer says. But she begs to differ. For the past five years, she says, “our ability to detect planets has absolutely flattened out.” Proxima b, a planet 1.3 times the mass of Earth, is the smallest-mass planet yet found with the radial velocity technique. But scientists only found it because Proxima is so close (cosmically speaking) to us, as well as very close to its low-mass star. Because of those proximities, the back-and-forth showed up stronger than it would have in a different system.

    Fischer (and every other exoplanet scientist) wants to find more worlds like that. But current instruments, including HARPS, can only pick up velocities of about 1 meter per second—10 times higher than Earth’s 10 centimeter per second pull on the Sun. “The precision of our instruments isn’t good enough,” says Fischer. “That’s what EXPRES is setting out to try to change.”

    Algorithmic advances

    The team has changed the physical technology—the hardware—to make EXPRES more precise. But the EXPRES team also innovates on the software side, using simulations to inform hardware development and subtracting out intractable noise.

    Here’s the problem: The red- and blueshifts in starlight don’t come only from gentle planetary prods.

    Stars are not calm beasts. Their atmospheres roil, boil, and send out huge plumes of particles and radiation. “It’s sort of like a fountain going off in every direction,” says Fischer. That movement—along with the stars’ wholesale motion—shifts the light. And scientists have to disentangle which shifts come from the fountain and which from the planetary tug-of-war.

    Planets shift the whole spectrum—from low-energy light to high-energy—at once, by the same amount. Atmospheric activity, on the other hand, causes different shifts in different parts of a star’s spectrum.

    Think about ultraviolet images of the Sun compared to infrared ones, says Fischer. In UV light, huge loops swing out from the solar atmosphere—they’re moving fast and shine much brighter than the Sun’s disk. Their velocity shifts show up strong. But switch to an IR picture of that same time period, and where the loops popped out, you’ll see only little surface spots. Because of their smallness and their slowness, they don’t really reveal themselves.

    That difference has let the team sift the global from the local. “As soon as you tell me there’s a difference, you’ve opened the door a crack,” says Fischer. “Now, we get to kick in the door.”

    EXPRES will ultra-finely split the light according to wavelength. And then before the team uses wavelength to calculate velocity, they find the “stellar jitter” and sift it out. And by “they,” they mean astrostatistician Jessi Cisewski, who developed the sort-and-separate algorithms.

    Road tripping

    The EXPRES team hopes to deliver the instrument to its permanent home—the Discovery Channel Telescope at Lowell Observatory in Flagstaff—in May of next year, and begin work by September 2017. They will drive it to Arizona in a U-Haul truck, with hopefully some thematic playlists blaring in the background.

    Discovery Channel Telescope at Lowell Observatory, Happy Jack AZ
    Discovery Channel Telescope at Lowell Observatory, Happy Jack AZ, USA

    The Discovery Channel Telescope is a good fit for EXPRES because it has active optics that autocorrect for distortions. It’s also a marsupial: It has a pouch for five different instruments and can switch between them in just 60 seconds. That way, even if there’s just a little bit of open time on the telescope, operators can switch to the EXPRES pouch at the end of someone else’s project, and only waste a minute. EXPRES will get data on the regular, which is key to seeing the periodic signals from planets.

    They’ll use that time to do the 100 Earths Project, looking at a few hundred well-studied stars all over the sky to find 100 Earth-ish-mass planets, creating a catalog big enough to actually draw conclusions.

    The EXPRES team is, of course, not the only group hoping to make it big with small-planet measurements. The closest comparable instrument will come from the same Geneva scientists who developed HARPS. This project—called ESPRESSO—will arrive at the Very Large Telescope in Chile around the same time EXPRES gets to Arizona.

    ESO/Espresso on the VLT
    ESO/Espresso on the VLT

    “The planet Proxima Centauri b, which was recently discovered with HARPS, is a foretaste of what will be possible with ESPRESSO,” says Francesco Pepe, who leads ESPRESSO’s evolution. He says the hard- and software will also let them look into the atmospheres of other worlds from the surface of our own, exposing “the ‘inner nature’ of exoplanets.”

    In a 2013 presentation, Pepe recalled a time 10 years before, when HARPS first put eyes on the sky and scientists thought they had butted up against technological and stellar limits. Radial-velocity searches had gotten as good as they could get, people thought (silly people). “Today, we know that reality is different, fortunately,” he said.

    Now, they will just have to see who makes that reality reality first. Regardless, the instrument name will begin with an E.

    See the full article here .

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  • richardmitnick 8:54 am on July 13, 2016 Permalink | Reply
    Tags: , Colli Albani Volcanic District on the outskirts of Rome, , WIRED   

    From WIRED: “Could a Volcano Be Waking Up on the Outskirts of Rome?” 

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    Wired

    07.13.16
    Erik Klemetti

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    An aerial view of Castel Gandolfo, Lake Albano and the Alban Hills in Lazio, Italy. DeAgostini/Getty Images

    Italy has some of the most potentially hazardous volcanoes on Earth. The pair of Vesuvius and the Campi Flegrei around the Bay of Naples are a looming danger for over 3 million people when either of those volcanoes reawakens. Etna, although not as directly hazardous as Vesuvius, is one of the most active volcanoes on the planet, and its explosive eruptions can impact air travel. New research in Geophysical Research Letters by Fabrizio Marra and others is suggesting we add another to the list of potentially perilous Italian volcanoes: the Colli Albani Volcanic District on the outskirts of Rome.

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    https://www.researchgate.net/figure/263410453_fig1_Fig-1-Digital-Elevation-Model-of-the-Colli-Albani-Volcanic-District-showing-the-main

    Now, the Colli Albani (also known as the Alban Hills) has already been identified as having a volcanic past. It consists of a large caldera (10 by 12 kilometers) that was likely created during the Colli Albani’s most active period from 608,000 to 351,000 years ago. That’s when it produced some massive explosive eruptions totaling over 280 cubic kilometers (67 cubic miles!) of volcanic debris. Since then, activity has calmed down, with a period from 309,000 to 241,000 years ago that was dominated by strombolian eruptions and lava flows (think Etna). The area’s most recent activity has been mainly small explosive eruptions of less than 1 cubic kilometer each, forming small cones or maars (pits).

    This change in behavior is good news for Rome, because the Colli Albani appears to be more regular in the spacing of its eruptions than most volcanoes. In their new study, Marra and team identify dormancy and recurrence intervals for the Colli Albani that, since 608,000 years ago, have varied from 29,000±2,000 to 57,000±4,000 years, averaging 41,000±2,000 years between eruptions and 38,000±2,000 years between periods of renewed activity (see below). If you look at the last 100,000 years (Caution: small sample size!), Marra and others argue that the recurrence interval drops to ~31,000 years. Considering it has been 36,000 years since the last eruptions, they claim that the Colli Albani might be ready for new eruptions.

    3
    Figure from Marra and others (2016), showing eruptions at the Colli Albani over the past 900,000 years. The recurrence interval of eruptions is marked in yellow since ~600,000 years. The red line represents uplift in the area while the grey peaks represent the volume and duration of eruptions.Marra and others (2016), Geophysical Research Letters

    Why would the Colli Albani be such a well-behaved volcanic system when it comes to regularly-spaced eruptive activity? Marra and others suggest that the regional stress changes due the the tectonic setting (subduction and extension, a strange combination) of this part of Italy can cause the Colli Albani to become active again. As the stresses change, they can either seal pathways for magma to reach the surface (cause “dormancy”) or open those pathways (extension), causing new magma to rise towards the surface, generating uplift and hydrothermal features. Based on observations of recent earthquakes and borehole data, it appears that the area has entered a period of extension in the last few hundred years.

    On their own, these ideas might be intriguing but not a cause for concern. However, studies of the land’s surface around Rome by InSAR and geodetic surveys over the last ~50 years have shown 50 centimeters (~20 inches) of uplift in the parts of the Colli Albani that have seen previous eruptions. Since 1993, an area on the western side of the Colli Albani has been rising on average 2.6 mm (0.1 inches) per year.

    The region also saw small earthquake swarms in 1990-91. And regional geophysical studies suggest that somewhere beneath the Colli Albani—at depths between 5-10 kilometers (3.1-6.2 miles)—is a zone that could be partially molten magma. (To add to the fun, three years ago a new fumarole [vent for volcanic gases] opened near the Leonardo da Vinci International Airport, although its distance from the Colli Albani makes it a tenuous connection to this activity).

    So, we have a volcanic system that seems to regularly reactivate on timescales of ~31-36,000 years, and it’s been about that amount of time since its last eruptions. Combine that with signs of volcanic unrest (albeit pretty mild signs), and you get an area that likely needs close attention, especially considering it is only 25 kilometers (16 miles) from central Rome.

    See the full article here .

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  • richardmitnick 4:15 pm on June 17, 2016 Permalink | Reply
    Tags: A new fundamental particle, Anomaly in the decays of excited beryllium-8 atoms, , , The Mysterious X Boson Could Upend the Standard Model. If It Actually Exists, WIRED, X Boson   

    From WIRED: “The Mysterious X Boson Could Upend the Standard Model. If It Actually Exists” 

    Wired logo

    Wired

    06.17.16
    Natalie Wolchover

    1
    This experimental apparatus at the Institute for Nuclear Research at the Hungarian Academy of Sciences in Debrecen was used to detect possible evidence of a new particle.Courtesy of Attila Krasznahorkay

    Last year, a team of nuclear physicists in Hungary observed an anomaly in the decays of excited beryllium-8 atoms—an unexpected preference for spitting out pairs of particles with a particular angle of separation. The bump in the physicists’ data was unmistakable, with odds of less than one in 100 billion of arising by chance. Reporting the anomaly in Physical Review Letters in January, the researchers argued that it could signify the existence of a new fundamental particle. But at first, few took notice.

    That changed in April with a much-discussed paper by Jonathan Feng, a theoretical particle physicist at the University of California, Irvine, and colleagues. After spending months translating the nuclear physics finding into the language of particle physics and ensuring that no particle physics experiments contradicted it, the Irvine team determined that the beryllium-8 anomaly is “beautifully” explained by the presence of a previously unknown “vector boson”—a type of particle that would wield a little-felt fifth force of nature.

    The proposed boson has become lunch-table talk in physics departments far and wide, and plans are afoot for testing the idea. If the particle is confirmed, it would be a definite “ticket to Stockholm” that “would completely upend our understanding of the universe,” said Jesse Thaler, a theoretical particle physicist at the Massachusetts Institute of Technology. Unlike the Higgs boson—the particle discovered in 2012 that was the last missing piece of the Standard Model of particle physics—this unforeseen boson and accompanying force would lead the way to a more complete theory of nature.

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.
    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth

    Physicists desperately seek an extension of the Standard Model to account for dark matter, neutrino masses, unification of the forces and other mysteries. (In a forthcoming paper, the Irvine team will propose a Standard Model extension that includes the new boson.) Stressing that he has a high bar for experimental anomalies after seeing many bumps come and go in the past, Feng said, “I’m more excited than I’ve been about things for a long time.”

    Remarkably, whereas the world’s biggest supercollider was needed to produce the heavy Higgs boson, the hypothetical Hungarian boson is so lightweight, with a mass only 34 times that of the electron, that it could have turned up in experiments decades ago. If it really exists, how did it go unnoticed for so long? Most experts will remain skeptical until further evidence of the particle rolls in—even Feng. “It’s a huge claim to say a fifth force has been discovered, and I recognize that,” he said. “Obviously, you need to check it.”

    See the full article here .

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  • richardmitnick 12:12 pm on May 21, 2016 Permalink | Reply
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    From WIRED: “New Evidence Could Overthrow the Standard View of Quantum Mechanics” 

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    WIRED

    05.21.16
    Dan Falk

    1
    Olena Shmahalo/Quanta Magazine

    Of the many counterintuitive features of quantum mechanics, perhaps the most challenging to our notions of common sense is that particles do not have locations until they are observed. This is exactly what the standard view of quantum mechanics, often called the Copenhagen interpretation, asks us to believe. Instead of the clear-cut positions and movements of Newtonian physics, we have a cloud of probabilities described by a mathematical structure known as a wave function. The wave function, meanwhile, evolves over time, its evolution governed by precise rules codified in something called the Schrödinger equation. The mathematics are clear enough; the actual whereabouts of particles, less so. Until a particle is observed, an act that causes the wave function to “collapse,” we can say nothing about its location. Albert Einstein, among others, objected to this idea. As his biographer Abraham Pais wrote: “We often discussed his notions on objective reality. I recall that during one walk Einstein suddenly stopped, turned to me and asked whether I really believed that the moon exists only when I look at it.”

    But there’s another view—one that’s been around for almost a century—in which particles really do have precise positions at all times. This alternative view, known as pilot-wave theory or Bohmian mechanics, never became as popular as the Copenhagen view, in part because Bohmian mechanics implies that the world must be strange in other ways. In particular, a 1992 study claimed to crystalize certain bizarre consequences of Bohmian mechanics and in doing so deal it a fatal conceptual blow. The authors of that paper concluded that a particle following the laws of Bohmian mechanics would end up taking a trajectory that was so unphysical—even by the warped standards of quantum theory—that they described it as “surreal.”

    Nearly a quarter-century later, a group of scientists has carried out an experiment in a Toronto laboratory that aims to test this idea. And if their results, first reported* earlier this year, hold up to scrutiny, the Bohmian view of quantum mechanics—less fuzzy but in some ways more strange than the traditional view—may be poised for a comeback.

    Saving Particle Positions

    Bohmian mechanics was worked out by Louis de Broglie in 1927 and again, independently, by David Bohm in 1952, who developed it further until his death in 1992. (It’s also sometimes called the de Broglie–Bohm theory.) As with the Copenhagen view, there’s a wave function governed by the Schrödinger equation. In addition, every particle has an actual, definite location, even when it’s not being observed. Changes in the positions of the particles are given by another equation, known as the “pilot wave” equation (or “guiding equation”). The theory is fully deterministic; if you know the initial state of a system, and you’ve got the wave function, you can calculate where each particle will end up.

    That may sound like a throwback to classical mechanics, but there’s a crucial difference. Classical mechanics is purely “local”—stuff can affect other stuff only if it is adjacent to it (or via the influence of some kind of field, like an electric field, which can send impulses no faster than the speed of light). Quantum mechanics, in contrast, is inherently nonlocal. The best-known example of a nonlocal effect—one that Einstein himself considered, back in the 1930s—is when a pair of particles are connected in such a way that a measurement of one particle appears to affect the state of another, distant particle. The idea was ridiculed by Einstein as “spooky action at a distance.” But hundreds of experiments, beginning in the 1980s, have confirmed that this spooky action is a very real characteristic of our universe.

    In the Bohmian view, nonlocality is even more conspicuous. The trajectory of any one particle depends on what all the other particles described by the same wave function are doing. And, critically, the wave function has no geographic limits; it might, in principle, span the entire universe. Which means that the universe is weirdly interdependent, even across vast stretches of space. The wave function “combines—or binds—distant particles into a single irreducible reality,” as Sheldon Goldstein, a mathematician and physicist at Rutgers University, has written.

    The differences between Bohm and Copenhagen become clear when we look at the classic “double slit” experiment, in which particles (let’s say electrons) pass through a pair of narrow slits, eventually reaching a screen where each particle can be recorded. When the experiment is carried out, the electrons behave like waves, creating on the screen a particular pattern called an “interference pattern.” Remarkably, this pattern gradually emerges even if the electrons are sent one at a time, suggesting that each electron passes through both slits simultaneously.

    Those who embrace the Copenhagen view have come to live with this state of affairs—after all, it’s meaningless to speak of a particle’s position until we measure it. Some physicists are drawn instead to the Many Worlds interpretation of quantum mechanics, in which observers in some universes see the electron go through the left slit, while those in other universes see it go through the right slit—which is fine, if you’re comfortable with an infinite array of unseen universes.

    By comparison, the Bohmian view sounds rather tame: The electrons act like actual particles, their velocities at any moment fully determined by the pilot wave, which in turn depends on the wave function. In this view, each electron is like a surfer: It occupies a particular place at every specific moment in time, yet its motion is dictated by the motion of a spread-out wave. Although each electron takes a fully determined path through just one slit, the pilot wave passes through both slits. The end result exactly matches the pattern one sees in standard quantum mechanics.

    2
    Lucy Reading-Ikkanda for Quanta Magazine

    For some theorists, the Bohmian interpretation holds an irresistible appeal. “All you have to do to make sense of quantum mechanics is to say to yourself: When we talk about particles, we really mean particles. Then all the problems go away,” said Goldstein. “Things have positions. They are somewhere. If you take that idea seriously, you’re led almost immediately to Bohm. It’s a far simpler version of quantum mechanics than what you find in the textbooks.” Howard Wiseman, a physicist at Griffith University in Brisbane, Australia, said that the Bohmian view “gives you a pretty straightforward account of how the world is…. You don’t have to tie yourself into any sort of philosophical knots to say how things really are.”

    But not everyone feels that way, and over the years the Bohm view has struggled to gain acceptance, trailing behind Copenhagen and, these days, behind Many Worlds as well. A significant blow came with the paper known as “ESSW,”** an acronym built from the names of its four authors. The ESSW paper claimed that particles can’t follow simple Bohmian trajectories as they traverse the double-slit experiment. Suppose that someone placed a detector next to each slit, argued ESSW, recording which particle passed through which slit. ESSW showed that a photon could pass through the left slit and yet, in the Bohmian view, still end up being recorded as having passed through the right slit. This seemed impossible; the photons were deemed to follow “surreal” trajectories, as the ESSW paper put it.

    The ESSW argument “was a striking philosophical objection” to the Bohmian view, said Aephraim Steinberg, a physicist at the University of Toronto. “It damaged my love for Bohmian mechanics.”

    But Steinberg has found a way to rekindle that love. In a paper published*** in Science Advances, Steinberg and his colleagues—the team includes Wiseman, in Australia, as well as five other Canadian researchers—describe what happened when they actually performed the ESSW experiment. They found that the photon trajectories aren’t surrealistic after all—or, more precisely, that the paths may seem surrealistic, but only if one fails to take into account the nonlocality inherent in Bohm’s theory.

    The experiment that Steinberg and his team conducted was analogous to the standard two-slit experiment. They used photons rather than electrons, and instead of sending those photons through a pair of slits, they passed through a beam splitter, a device that directs a photon along one of two paths, depending on the photon’s polarization. The photons eventually reach a single-photon camera (equivalent to the screen in the traditional experiment) that records their final position. The question “Which of two slits did the particle pass through?” becomes “Which of two paths did the photon take?”

    Importantly, the researchers used pairs of entangled photons rather than individual photons. As a result, they could interrogate one photon to gain information about the other. When the first photon passes through the beam splitter, the second photon “knows” which path the first one took. The team could then use information from the second photon to track the first photon’s path. Each indirect measurement yields only an approximate value, but the scientists could average large numbers of measurements to reconstruct the trajectory of the first photon.

    The team found that the photon paths do indeed appear to be surreal, just as ESSW predicted: A photon would sometimes strike one side of the screen, even though the polarization of the entangled partner said that the photon took the other route.

    But can the information from the second photon be trusted? Crucially, Steinberg and his colleagues found that the answer to the question “Which path did the first photon take?” depends on when it is asked.

    At first—in the moments immediately after the first photon passes through the beam splitter—the second photon is very strongly correlated with the first photon’s path. “As one particle goes through the slit, the probe [the second photon] has a perfectly accurate memory of which slit it went through,” Steinberg explained.

    But the farther the first photon travels, the less reliable the second photon’s report becomes. The reason is nonlocality. Because the two photons are entangled, the path that the first photon takes will affect the polarization of the second photon. By the time the first photon reaches the screen, the second photon’s polarization is equally likely to be oriented one way as the other—thus giving it “no opinion,” so to speak, as to whether the first photon took the first route or the second (the equivalent of knowing which of the two slits it went through).

    The problem isn’t that Bohm trajectories are surreal, said Steinberg. The problem is that the second photon says that Bohm trajectories are surreal—and, thanks to nonlocality, its report is not to be trusted. “There’s no real contradiction in there,” said Steinberg. “You just have to always bear in mind the nonlocality, or you miss something very important.”

    Faster Than Light

    Some physicists, unperturbed by ESSW, have embraced the Bohmian view all along and aren’t particularly surprised by what Steinberg and his team found. There have been many attacks on the Bohmian view over the years, and “they all fizzled out because they had misunderstood what the Bohm approach was actually claiming,” said Basil Hiley, a physicist at Birkbeck, University of London (formerly Birkbeck College), who collaborated with Bohm on his last book, The Undivided Universe. Owen Maroney, a physicist at the University of Oxford who was a student of Hiley’s, described ESSW as “a terrible argument” that “did not present a novel challenge to de Broglie–Bohm.” Not surprisingly, Maroney is excited by Steinberg’s experimental results, which seem to support the view he’s held all along. “It’s a very interesting experiment,” he said. “It gives a motivation for taking de Broglie–Bohm seriously.”

    On the other side of the Bohmian divide, Berthold-Georg Englert, one of the authors of ESSW (along with Marlan Scully, George Süssman and Herbert Walther), still describes their paper as a “fatal blow” to the Bohmian view. According to Englert, now at the National University of Singapore, the Bohm trajectories exist as mathematical objects but “lack physical meaning.”

    On a historical note, Einstein lived just long enough to hear about Bohm’s revival of de Broglie’s proposal—and he wasn’t impressed, dismissing it as too simplistic to be correct. In a letter to physicist Max Born, in the spring of 1952, Einstein weighed in on Bohm’s work:

    “Have you noticed that Bohm believes (as de Broglie did, by the way, 25 years ago) that he is able to interpret the quantum theory in deterministic terms? That way seems too cheap to me. But you, of course, can judge this better than I.”

    But even for those who embrace the Bohmian view, with its clearly defined particles moving along precise paths, questions remain. Topping the list is an apparent tension with special relativity, which prohibits faster-than-light communication. Of course, as physicists have long noted, nonlocality of the sort associated with quantum entanglement does not allow for faster-than-light signaling (thus incurring no risk of the grandfather paradox or other violations of causality). Even so, many physicists feel that more clarification is needed, especially given the prominent role of nonlocality in the Bohmian view. The apparent dependence of what happens here on what may be happening there cries out for an explanation.

    “The universe seems to like talking to itself faster than the speed of light,” said Steinberg. “I could understand a universe where nothing can go faster than light, but a universe where the internal workings operate faster than light, and yet we’re forbidden from ever making use of that at the macroscopic level—it’s very hard to understand.”

    *Science paper:
    Experimental nonlocal and surreal Bohmian trajectories

    **Science paper:
    Surrealistic Bohm Trajectories

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  • richardmitnick 10:32 am on May 6, 2016 Permalink | Reply
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    From wired: “Mount St. Helens Is Recharging Its Magma Stores, Setting Off Earthquake Swarms” 

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    Wired

    05.05.16
    Erik Klemetti

    1
    Mt St Helens, Washington, USA

    2
    This GPS station on Mount St. Helens is one of the many ways volcanologists can monitor the day-to-day activity at an active volcano (even when its at rest).Adam Mosbrucker / USGS

    When it comes down to it, volcanoes spend most of their existence not erupting. If you look at almost any volcano, it might have a bout of eruption for days to months at a time, then go quiet for decades, centuries or more. So when you think about the activity at any given volcano, you should not only concern yourself with what might be happening when the volcano is actually coughing stuff up (erupting), but also when, at the surface, things look perfectly calm.

    There are a number of ways to examine what a volcano was/is doing during these periods of repose. My research* is like that of a historian, trying to understand what was going on before eruptions that have already happened. I do this by looking at the evidence of changes in the magmatic system recorded in the crystals that are brought up during an eruption. There you find the record of intrusions of new magma occurring frequently, even during times when the volcanic system might not erupt for 100,000 years! So the real action at many volcanoes might be happening kilometers beneath our feet.

    Now, if you want to be more like a journalist and look at what might be going in at the moments between eruptions, you can turn to seismology. At many volcanoes, there is a constant background din of small earthquakes caused by magma, hot gasses, hot water, or faults underneath the volcano. They can occur in swarms and across a wide range of depths—from the mantle source of the magma all the way to the surface. You can use the number of earthquakes and their depth to start to weave a story of how magma might be moving underneath a volcano during those quiet periods.

    2
    Sometimes keeping a seismic station running during winter is difficult. USGS technicians Kelly Swinford and Amberlee Darold are shown here getting a St. Helens station back online on March 30, 2016.Seth Moran / USGS

    The USGS and the Pacific Northwest Seismic Network has arrays of seismometers on many of the Cascade volcanoes to watch these earthquakes, so hopefully we’ll know well in advance if any of these volcanoes are waking up. It isn’t easy to keep the seismic array on these volcanoes running during the winter, as the picture of the seismometer on Mount St. Helens above image shows! So you should be impressed that we have the near real-time seismic data at our fingertips.

    One such story of a volcano recharging is being written right now at Mount St. Helens in Washington. Since the start of 2016 (see below), an earthquake swarm has been detected underneath the currently-quiet Washington volcano. These earthquakes have been occurring from depths of ~2 to over 7 kilometers beneath the volcano. USGS volcanologists and seismologists are interpreting this swarm as a response to the slow “recharging” for the volcano, where new magma is rising up underneath St. Helens as it slumbers. As the magma intrudes, it imparts pressure on the rock around it and it heats up water/releases gases that can add to that pressure. This generates small earthquakes as the rocks shift in response to that stress.

    3
    A compilation of earthquakes under Mount St. Helens from 1988-2016. Magmatic recharge swarms are marked, along with the most recent earthquake swarm. USGS / Cascade Volcano Observatory.

    Now, this might make some people nervous, but if you look at the compilation of earthquakes from St. Helens over its periods of repose since 1988 (see above), you can see that it has had a lot of recharge events—and most of these don’t directly lead to an eruption. In fact, if you look at the biggest recharge swarms prior to the 2004 revival of eruptions, it might have been 5 years between that big recharge event in 1998-99 and the 2004 eruptions.

    Even in the time since the end of the 2004-08 eruptions, there have been little earthquake swarms: early 2012, early 2014, and now the most vigorous in 2016. These are all normal behavior for a volcano as active as St. Helens. As the USGS report on the earthquake swarm mentions, there are no other signs of potential eruption right now: no changes in gas emissions, no deformation, and no shallow seismicity (<2 kilometers) that are generally associated with an impeding eruption. However, it does mean that even as St. Helens sleeps, the magma that will likely take part in the next eruption is working its way up towards the surface, likely stopping along the way to crystallize and interact with the residue of previous eruptions.

    It might take a big recharge event to really get the system primed for the next eruption. This question—what might ultimately trigger that next eruption—is one of the big ones in volcanology. However, what we can say is that no volcano is truly “dormant” when it’s not erupting. It’s just that most of the action is happening far beneath our feet.

    *Science Paper:
    Localized Rejuvenation of a Crystal Mush Recorded in Zircon Temporal and Compositional Variation at the Lassen Volcanic Center, Northern California

    See the full article here .

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  • richardmitnick 7:02 pm on January 27, 2016 Permalink | Reply
    Tags: , , , , , WIRED   

    From WIRED.com: “The Death of General Relativity Lurks in a Black Hole’s Shadow” 

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    Wired

    01.27.16
    Lizzie Wade

    Black hole in color
    Chi-kwan Chan, Feryal Ozel, and Dimitrios Psaltis

    Nothing gets out of a black hole—not even light. Once a star, a planet, a piece of dust, or even a single photon crosses the limit known as the event horizon, it’s not coming out again. Pulled into the crushing gravity of the singularity at the black hole’s heart, it vanishes from the universe.

    That’s a big problem if what you really want from a black hole is a photograph. By definition, it’s impossible. All light getting sucked in means no light reflects back—so a black hole is invisible, across the spectrum. And, duh, invisible objects don’t show up in photographs.

    But thanks to a new telescope, Tim Johannsen, an astrophysicist at the Perimeter Institute and the University of Waterloo in Ontario, Canada, may be able to get a black hole pic after all. A loophole in physics means he might be able to see not the black hole itself, but its shadow. And, no big deal, but that photo just might overturn Albert Einstein’s theory of general relativity.

    So…wait. Black holes have shadows? Sort of. As gas and dust and other cosmic material approaches a black hole, “that stuff heats up, like millions and millions of degrees,” Johannsen says. That superheated matter swirls around the black hole in what’s called an accretion disk; because it’s so hot, the accretion disk emits a lot of light.

    Some of those photons zoom out towards Earthbound telescopes, while others cross the event horizon and fall into the void. So when astronomers look at a black hole, what they expect to see is a ring of bright light—the accretion disk—surrounding a circle of nothingness. That circle of nothingness is the shadow. (The black hole itself is just a single point within.) You can see a model of that here:


    Download mp4 video here .

    At least, that’s the idea. No one has ever actually seen a black hole’s shadow. “Despite their enormous mass, black holes are also exceedingly small,” says Avery Broderick, Johannsen’s colleague at the Perimeter Institute and the University of Waterloo. Seen from Earth, the shadow of Sagittarius A*, the supermassive black hole at the center of the Milky Way (also known as Sgr A*, which astrophysicists pronounce “Saj-A-star”) is just 1/35,000,000th the width of the Moon, or 50 microarcseconds wide.

    Sag A prime
    Sgr A*

    Here’s where that new telescope comes in. Maybe. Johannsen, Broderick, and their colleagues hope the Event Horizon Telescope will be able to resolve Sgr A*’s shadow. The EHT is actually nine [radio] telescopes (and counting), all working together and each located in a different spot on Earth.

    Event Horizon Telescope map
    EHT map

    Telescopes of the EHT

    ALMA

    ALMA Array
    APEX

    ESO APEX

    Arizona Radio Observatory (U. of Arizona)

    Arizona Radio Observatory

    Caltech Submillimeter Observatory

    Caltech Submillimeter Observatory

    CARMA

    CARMA Array

    Harvard Smithsonian Center for Astrophysics Submillimeter Array

    SMA Submillimeter Array

    Institut de Radioastronomie Millimetrique (IRAM) 30m

    IRAM

    James Clerk Maxwell Telescope (JCMT)

    The Large Millimeter Telescope Alfonso Serrano (LMT)

    Plateau de Bure interferometer

    IRAM Interferometer Submillimeter Array of Radio Telescopes

    South Pole Telescope]

    South Pole Telescope

    Coordinating those telescopes’ observations allows them to work as one big telescope that is, in essence, as big as the planet. The bigger your telescope, the higher your resolution. “The Event Horizon Telescope has the capability to produce the highest-resolution images in the history of astronomy”, Broderick says. “That means, for the first time, we can see what happens right down in the immediate vicinity of black hole event horizons.”

    Scientists working on the EHT hope to see images in the spring of 2017. But they already have some ideas of what they’ll get. General relativity describes gravity not as a force drawing two objects together, but rather as the warped spacetime that governs each of those objects movements.

    Spacetime with Gravity Probe B
    Artist concept of Gravity Probe B orbiting the Earth to measure space-time, a four-dimensional description of the universe including height, width, length, and time. NASA

    Concentrate a big enough mass in a small enough region of spacetime, and its gravity will be inescapably huge—voila, you’ve got a black hole. If that sounds weird to you, well, it took 50 years for astronomers to discover that black holes were real objects, not just a quirk of general relativity’s math.

    The problem is, general relativity is really good at describing giant things like stars, but breaks down utterly when it comes to really teeny tiny things like photons and quarks. To talk about those, you need a different theory: quantum mechanics. The central problem in physics today is that the theories are fundamentally incompatible. To figure that out, physicists are keen to find places where the theories overlap or break down—like, for example, the event horizon of a black hole.

    General relativity doesn’t just predict the existence of black holes. It also precisely describes the size and shape of their shadows. Sgr A*’s shadow is supposed to be perfectly circular and 50 microarcseconds wide. “What would it look like if general relativity were wrong?” wonders Broderick (and just about every other astrophysicist on the planet). There are two possibilities. “The shadow could be more egg shaped,” says Johannsen. “That would be a smoking gun for a GR violation.” It might also be slightly smaller or bigger than general relativity predicts. All he needs to figure it out is the picture from the EHT. (Johannsen and Broderick just published a paper outlining their strategy in Physical Review Letters.)

    And what if Sgr A*’s shadow doesn’t look the way general relativity says it should? Well, that would be great. If the results held up, physicists could start looking for alternative theories of gravity that did predict the shadow’s size and shape. Success wouldn’t mean the new theory would automatically be the successor to general relativity, of course. But it’s a good way to figure out which theories might be on the right track, so you can give their other predictions a closer look.

    Johannsen’s favorite possibility involves extra dimensions. A shortcoming of general relativity is that it doesn’t explain why gravity is so much weaker than the other fundamental forces. “Let’s assume there is another space dimension. Gravity would immediately penetrate that and become kind of diluted,” Johannsen says. In other words, gravity isn’t weak, it’s just working across more dimensions than the other forces. Amazingly, theories that predict those extra dimensions also predict a different size for Sgr A*’s shadow. In a couple years, finally proving—or falsifying—this weird new physics could “literally be as ‘easy’ as putting a ruler across the image,” Johannsen says.

    “We’re getting this amazing opportunity to finally put Einstein to the test around the most enigmatic and striking predictions of this theory,” Broderick says. If Einstein is wrong, general relativity won’t go away—it’s too good at what it does. It just won’t be the whole story anymore. Isaac Newton was plenty right about how gravity worked here on Earth; Einstein revolutionized our understanding of the universe. But the universe is big enough to have room for someone to come along and do it again.

    See the full article here .

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