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  • richardmitnick 5:08 pm on September 16, 2018 Permalink | Reply
    Tags: Astronomers Have Found the Universe's Missing Matter, , , , , WIRED   

    From WIRED: “Astronomers Have Found the Universe’s Missing Matter” 

    Wired logo

    from WIRED

    1
    A computer simulation of the hot gas between galaxies hinted at the location of the universe’s missing matter. Princeton University/Renyue Cen.

    09.16.18
    Katia Moskvitch

    For decades, some of the atomic matter in the universe had not been located. Recent papers reveal where it’s been hiding. [No papers cited]

    Astronomers have finally found the last of the missing universe. It’s been hiding since the mid-1990s, when researchers decided to inventory all the “ordinary” matter in the cosmos—stars and planets and gas, anything made out of atomic parts. (This isn’t “dark matter,” which remains a wholly separate enigma.) They had a pretty good idea of how much should be out there, based on theoretical studies of how matter was created during the Big Bang. Studies of the cosmic microwave background (CMB)—the leftover light from the Big Bang—would confirm these initial estimates.

    So they added up all the matter they could see—stars and gas clouds and the like, all the so-called baryons. They were able to account for only about 10 percent of what there should be. And when they considered that ordinary matter makes up only 15 percent of all matter in the universe—dark matter makes up the rest—they had only inventoried a mere 1.5 percent of all matter in the universe.

    Now, in a series of three recent papers, astronomers have identified the final chunks of all the ordinary matter in the universe. (They are still deeply perplexed as to what makes up dark matter.) And despite the fact that it took so long to identify it all, researchers spotted it right where they had expected it to be all along: in extensive tendrils of hot gas that span the otherwise empty chasms between galaxies, more properly known as the warm-hot intergalactic medium, or WHIM.

    Early indications that there might be extensive spans of effectively invisible gas between galaxies came from computer simulations done in 1998. “We wanted to see what was happening to all the gas in the universe,” said Jeremiah Ostriker, a cosmologist at Princeton University who constructed one of those simulations along with his colleague Renyue Cen. The two ran simulations of gas movements in the universe acted on by gravity, light, supernova explosions and all the forces that move matter in space. “We concluded that the gas will accumulate in filaments that should be detectable,” he said.

    Except they weren’t — not yet.

    “It was clear from the early days of cosmological simulations that many of the baryons would be in a hot, diffuse form — not in galaxies,” said Ian McCarthy, an astrophysicist at Liverpool John Moores University. Astronomers expected these hot baryons to conform to a cosmic superstructure, one made of invisible dark matter, that spanned the immense voids between galaxies. The gravitational force of the dark matter would pull gas toward it and heat the gas up to millions of degrees. Unfortunately, hot, diffuse gas is extremely difficult to find.

    To spot the hidden filaments, two independent teams of researchers searched for precise distortions in the CMB, the afterglow of the Big Bang. As that light from the early universe streams across the cosmos, it can be affected by the regions that it’s passing through. In particular, the electrons in hot, ionized gas (such as the WHIM) should interact with photons from the CMB in a way that imparts some additional energy to those photons. The CMB’s spectrum should get distorted.

    Unfortunately the best maps of the CMB (provided by the Planck satellite) showed no such distortions. Either the gas wasn’t there, or the effect was too subtle to show up.

    CMB per ESA/Planck


    ESA/Planck 2009 to 2013

    But the two teams of researchers were determined to make them visible. From increasingly detailed computer simulations of the universe, they knew that gas should stretch between massive galaxies like cobwebs across a windowsill. Planck wasn’t able to see the gas between any single pair of galaxies. So the researchers figured out a way to multiply the faint signal by a million.

    First, the scientists looked through catalogs of known galaxies to find appropriate galaxy pairs — galaxies that were sufficiently massive, and that were at the right distance apart, to produce a relatively thick cobweb of gas between them. Then the astrophysicists went back to the Planck data, identified where each pair of galaxies was located, and then essentially cut out that region of the sky using digital scissors. With over a million clippings in hand (in the case of the study led by Anna de Graaff, a Ph.D. student at the University of Edinburgh), they rotated each one and zoomed it in or out so that all the pairs of galaxies appeared to be in the same position. They then stacked a million galaxy pairs on top of one another. (A group led by Hideki Tanimura at the Institute of Space Astrophysics in Orsay, France, combined 260,000 pairs of galaxies.) At last, the individual threads — ghostly filaments of diffuse hot gas — suddenly became visible.

    2
    (A) Images of one million galaxy pairs were aligned and added together. (B) Astronomers mapped all the gas within the actual galaxies. (C) By subtracting the galaxies (B) from the initial image (A), researchers revealed filamentary gas hiding in intergalactic space. Adapted by Quanta Magazine

    The technique has its pitfalls. The interpretation of the results, said Michael Shull, an astronomer at the University of Colorado at Boulder, requires assumptions about the temperature and spatial distribution of the hot gas. And because of the stacking of signals, “one always worries about ‘weak signals’ that are the result of combining large numbers of data,” he said. “As is sometimes found in opinion polls, one can get erroneous results when one has outliers or biases in the distribution that skew the statistics.”

    In part because of these concerns, the cosmological community didn’t consider the case settled. What was needed was an independent way of measuring the hot gas. This summer, one arrived.

    Lighthouse Effect

    While the first two teams of researchers were stacking signals together, a third team followed a different approach. They observed a distant quasar — a bright beacon from billions of light-years away — and used it to detect gas in the seemingly empty intergalactic spaces through which the light traveled. It was like examining the beam of a faraway lighthouse in order to study the fog around it.

    Usually when astronomers do this, they try to look for light that has been absorbed by atomic hydrogen, since it is the most abundant element in the universe. Unfortunately, this option was out. The WHIM is so hot that it ionizes hydrogen, stripping its single electron away. The result is a plasma of free protons and electrons that don’t absorb any light.

    So the group decided to look for another element instead: oxygen. While there’s not nearly as much oxygen as hydrogen in the WHIM, atomic oxygen has eight electrons, as opposed to hydrogen’s one. The heat from the WHIM strips most of those electrons away, but not all. The team, led by Fabrizio Nicastro of the National Institute for Astrophysics in Rome, tracked the light that was absorbed by oxygen that had lost all but two of its electrons. They found two pockets of hot intergalactic gas. The oxygen “provides a tracer of the much larger reservoir of hydrogen and helium gas,” said Shull, who is a member of Nicastro’s team. The researchers then extrapolated the amount of gas they found between Earth and this particular quasar to the universe as a whole. The result suggested that they had located the missing 30 percent.

    The number also agrees nicely with the findings from the CMB studies. “The groups are looking at different pieces of the same puzzle and are coming up with the same answer, which is reassuring, given the differences in their methods,” said Mike Boylan-Kolchin, an astronomer at the University of Texas, Austin.

    The next step, said Shull, is to observe more quasars with next-generation X-ray and ultraviolet telescopes with greater sensitivity. “The quasar we observed was the best and brightest lighthouse that we could find. Other ones will be fainter, and the observations will take longer,” he said. But for now, the takeaway is clear. “We conclude that the missing baryons have been found,” their team wrote.

    See the full article here .

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  • richardmitnick 6:57 am on September 3, 2018 Permalink | Reply
    Tags: , , , , , , , , , WIRED   

    From The Atlantic via WIRED: “China Built the World’s Largest Telescope. Then Came the Tourists” 

    Atlantic Magazine

    The Atlantic Magazine

    via

    Wired logo

    WIRED

    08.26.18
    Sarah Scoles

    Thousands of people moved[?*] to let China build and protect the world’s largest telescope. And then the government drew in orders of magnitude more tourists, potentially undercutting its own science in an attempt to promote it.

    FAST radio telescope, with phase arrays from Australia [https://sciencesprings.wordpress.com/2017/12/18/from-csiroscope-our-top-telescope-tech-travels-fast/] located in the Dawodang depression in Pingtang County, Guizhou Province, south China

    “I hope we go inside this golf ball,” Sabrina Stierwalt joked as she and a group of other radio astronomers approached what did, in fact, appear to be a giant golf ball in the middle of China’s new Pingtang Astronomy Town.

    Stierwalt was a little drunk, a lot full, even more tired. The nighttime scene felt surreal. But then again, even a sober, well-rested person might struggle to make sense of this cosmos-themed, touristy confection of a metropolis.

    On the group’s walk around town that night, they seemed to traverse the ever-expanding universe. Light from a Saturn-shaped lamp crested and receded, its rings locked into support pillars that appeared to make it levitate. Stierwalt stepped onto a sidewalk, and its panels lit up beneath her feet, leaving a trail of lights behind her like the tail of a meteor. Someone had even brought constellations down to Earth, linking together lights in the ground to match the patterns in the sky.

    1
    The tourist town, about 10 miles from the telescope, lights up at night. Credit Intentionally Withheld

    The day before, Stierwalt had traveled from Southern California to Pingtang Astronomy Town for a conference hosted by scientists from the world’s largest telescope. It was a new designation: China’s Five-Hundred-Meter Aperture Spherical Radio Telescope, or FAST, had been completed just a year before, in September 2016. Wandering, tipsy, around this shrine to the stars, the 40 or so other foreign astronomers had come to China to collaborate on the superlative-snatching instrument.

    For now, though, they wouldn’t get to see the telescope itself, nestled in a natural enclosure called a karst depression about 10 miles away. First things first: the golf ball.

    As the group got closer, they saw a red carpet unrolled into the entrance of the giant white orb, guarded by iridescent dragons on an inflatable arch. Inside, they buckled up in rows of molded yellow plastic chairs. The lights dimmed. It was an IMAX movie—a cartoon, with an animated narrator. Not the likeness of a person but … what was it? A soup bowl?

    No, Stierwalt realized. It was a clip-art version of the gargantuan telescope itself. Small cartoon FAST flew around big cartoon FAST, describing the monumental feat of engineering just over yonder: a giant geodesic dome shaped out of 4,450 triangular panels, above which receivers collect radio waves from astronomical objects.

    FAST’s dish, nestled into a depression, is made of thousands of triangular panels. located in the Dawodang depression in Pingtang County, Guizhou Province, south China located in the Dawodang depression in Pingtang County, Guizhou Province, south China VCGGetty Images

    China spent $180 million to create the telescope, which officials have repeatedly said will make the country the global leader in radio astronomy. But the local government also spent several times that on this nearby Astronomy Town—hotels, housing, a vineyard, a museum, a playground, classy restaurants, all those themed light fixtures. The government hopes that promoting their scope in this way will encourage tourists and new residents to gravitate to the historically poor Guizhou province.

    It is, in some sense, an experiment into whether this type of science and economic development can coexist. Which is strange, because normally, they purposefully don’t.

    The point of radio telescopes is to sense radio waves from space—gas clouds, galaxies, quasars. By the time those celestial objects’ emissions reach Earth, they’ve dimmed to near-nothingness, so astronomers build these gigantic dishes to pick up the faint signals. But their size makes them particularly sensitive to all radio waves, including those from cell phones, satellites, radar systems, spark plugs, microwaves, Wi-Fi, short circuits, and basically anything else that uses electricity or communicates. Protection against radio-frequency interference, or RFI, is why scientists put their radio telescopes in remote locations: the mountains of West Virginia, the deserts of Chile, the way-outback of Australia.

    FAST’s site used to be remote like that. The country even forcibly relocated thousands of villagers who lived nearby, so their modern trappings wouldn’t interfere with the new prized instrument.

    But then, paradoxically, the government built—just a few miles from the displaced villagers’ demolished houses—this astronomy town. It also plans to increase the permanent population by hundreds of thousands. That’s a lot of cell phones, each of which persistently emits radio waves with around 1 watt of power.

    By the time certain deep-space emissions reach Earth, their power often comes with 24+ zeroes in front: 0.0000000000000000000000001 watts.

    FAST has been in the making for a long time. In the early 2000s, China angled to host the Square Kilometre Array, a collection of coordinated radio antennas whose dishes would be scattered over thousands of miles. But in 2006, the international SKA committee dismissed China, and then chose to set up its distributed mondo-telescope in South Africa and Australia instead.

    Undeterred, Chinese astronomers set out to build their own powerful instrument.

    In 2007, China’s National Development and Reform Commission allocated $90 million for the project, with $90 million more streaming in from other agencies. Four years later, construction began in one of China’s poorest regions, in the karst hills of the southwestern part of the country. They do things fast in China: The team finished the telescope in just five years. In September 2016, FAST received its “first light,” from a pulsar 1,351 light-years away, during its official opening.

    A year later, Stierwalt and the other visiting scientists arrived in Pingtang, and after an evening of touring Astronomy Town, they got down to business.

    See, FAST’s opening had been more ceremony than science (the commissioning phase is officially scheduled to end by September 2019). It was still far from fully operational—engineers are still trying to perfect, for instance, the motors that push and pull its surface into shape, allowing it to point and focus correctly. And the relatively new crop of radio astronomers running the telescope were hungry for advice about how to run such a massive research instrument.

    The visiting astronomers had worked with telescopes that have contributed to understanding of hydrogen emissions, pulsars, powerful bursts, and distant galaxies. But they weren’t just subject experts: Many were logistical wizards, having worked on multiple instruments and large surveys, and with substantial and dispersed teams. Stierwalt studies interacting dwarf galaxies, and while she’s a staff scientist at Caltech/IPAC, she uses telescopes all over. “Each gives a different piece of the puzzle,” she says. Optical telescopes show the stars. Infrared instruments reveal dust and older stars. X-ray observatories pick out black holes. And single-dish radio telescopes like FAST see the bigger picture: They can map out the gas inside of and surrounding galaxies.

    So at the Radio Astronomy Conference, Stierwalt and the other visitors shared how FAST could benefit from their instruments, and vice versa, and talked about how to run big projects. That work had begun even before the participants arrived. “Prior to the meeting, I traveled extensively all over the world to personally meet with the leaders of previous large surveys,” says Marko Krčo, a research fellow who’s been working for the Chinese Academy of Sciences since the summer of 2016.

    He asked the meeting’s speakers, some of those same leaders, to talk about what had gone wrong in their own surveys, and how the interpersonal end had functioned. “How did you organize yourselves?” he says. “How did you work together? How did you communicate?”

    That kind of feedback would be especially important for FAST to accomplish one of its first, appropriately lofty goals: helping astronomers collect signals from many sides of the universe, all at once. They’d call it the Commensal Radio Astronomy FAST Survey, or CRAFTS.

    3
    Above the dish, engineers have suspended instruments that collect cosmic radio waves. Feature China/Barcroft Media/Getty Images

    Most radio astronomical surveys have a single job: Map gas. Find pulsars. Discover galaxies. They do that by collecting signals in a receiver suspended over the dish of a radio telescope, engineered to capture a certain range of frequencies from the cosmos. Normally, the different astronomer factions don’t use that receiver at the same time, because they each take their data differently. But CRAFTS aims to be the first survey that simultaneously collects data for such a broad spectrum of scientists—without having to pause to reconfigure its single receiver.

    CRAFTS has a receiver that looks for signals from 1.04 gigahertz to 1.45 gigahertz, about 10 times higher than your FM radio. Within that range, as part of CRAFTS, scientists could simultaneously look for gas inside and beyond the galaxy, scan for pulsars, watch for mysterious “fast radio bursts,” make detailed maps, and maybe even search for ET. “That sounds straightforward,” says Stierwalt. “Point the telescope. Collect the data. Mine the data.”

    4
    Engineers from FAST and the Australian science agency install the telescope’s CRAFTS receiver. Marko Krčo

    But it’s not easy. Pulsar astronomers want quicktime samples at a wide range of frequencies; hydrogen studiers, meanwhile, don’t need data chunks as often, but they care deeply about the granular frequency details. On top of that, each group adjusts the observations, calibrating them, kind of like you’d make sure your speedometer reads 45 mph when you’re going 45. And they use different kinds of adjustments.

    When we spoke, Krčo had just returned from a trip to Green Bank, where he was testing whether they could set everyone’s speedometer correctly. “I think it will be one of the big sort of legacies of FAST,” says Krčo. And it’s especially important since the National Science Foundation has recently cratered funding to both Arecibo and Green Bank observatories, the United States’ most significant single-dish radio telescopes.


    NAIC Arecibo Observatory, previously the largest radio telescope in the world operated by University of Central Florida, Yang Enterprises and UMET, Altitude 497 m (1,631 ft)

    Green Bank does have financial support, $2 million per year for five years from Yuri Milner’s Breaktrhough Listen Project.

    Breakthrough Listen Project

    1

    Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA



    GBO radio telescope, Green Bank, West Virginia, USA


    CSIRO/Parkes Observatory, located 20 kilometres north of the town of Parkes, New South Wales, Australia

    While they remain open, they have to seek private project money, meaning chunks of time are no longer available for astronomers’ proposals. Adding hours, on a different continent, helps everybody.

    At the end of the conference in Pingtang County, Krčo and his colleagues presented a concrete plan for CRAFTS, giving all the visitors a chance to approve the proposed design. “Each group could raise any red flags, if necessary, regarding their individual science goals or suggest modifications,” says Krčo.

    In addition to the CRAFTS receiver, Krčo says they’ll add six more, sensitive to different frequencies. Together, they will detect radio waves from 70 megahertz to 3 gigahertz. He says they’ll find thousands of new pulsars (as of July 2018, they had already found more than 40), and do detailed studies of hydrogen inside the galaxy and in the wider universe, among numerous other worthy scientific goals.

    “There’s just a hell of a lot of work to do to get there,” says Krčo. “But we’re doing it.”

    For FAST to fulfill its potential, though, Krčo and his colleagues won’t just have to solve engineering problems: They’ll also have to deal with the problems that engineering created.

    During the four-day Radio Astronomy Forum, Stierwalt and the other astronomers did, finally, get to see the actual telescope, taking a bus up a tight, tortuous road through the karst between town and telescope.

    As soon as they arrived on site, they were instructed to shut down their phones to protect the instrument from the radio frequency interference. But not even these astronomers, who want pristine FAST data for themselves, could resist pressing that capture button. “Our sweet, sweet tour guide continually reminded us to please turn off our phones,” says Stierwalt, “but we all kept taking pictures and sneaking them out because no one really seemed to care.” Come on: It’s the world’s largest telescope.

    Maybe their minder stayed lax because a burst here or there wouldn’t make much of a difference in those early days. The number of regular tourists allowed at the site all day is capped at 3,000, to limit RFI, and they have to put their phones in lockers before they go see the dish. Krčo says the site bumps up against the visitor limit most days.

    But tourism and development are complicated for a sensitive scientific instrument. Within three miles of the telescope, the government passed legislation establishing a “radio-quiet zone,” where RFI-emitting devices are severely restricted. No one (not cellular providers or radio broadcasters) can get a transmitting license, and people entering the facility itself will have their electronics confiscated. “No one lives inside the zone, and the area is not open to the general public,” says Krčo, although some with commercial interests, like local farmers, can enter the zone with special permission. The government relocated villagers who lived within that protected area with promises of repayment in cash, housing, and jobs in tourism and FAST support services. (Though a 2016 report in Agence France-Presse revealed that up to 500 relocated families were suing the Pingtang government, alleging “land grabs without compensation, forced demolitions and unlawful detentions.”)

    The country’s Civil Aviation Administration has also adjusted air travel, setting up two restricted flight zones near the scope, canceling two routes, and adding or adjusting three others. “We can still see some RFI from aircraft navigational beacons,” says Krčo. “It’s much less, though, compared to what it’d look like without the adjusted air routes. It’d be impossible to fully clear a large enough air space to create a completely quiet sky.”

    None of the invisible boundaries, after all, function like force fields. RFI that originates from beyond can pass right on through. At least at the five-star tourist hotel, around 10 miles away, there’s Wi-Fi. The tour center, says an American pulsar astronomer, has a direct line of sight to the telescope.

    When Krčo first arrived on the job, he stayed in the astronomy town. “Every morning, we were counting all the new buildings springing up overnight,” Krčo says. “It would be half a dozen.”

    One day, he woke up to a new five-story structure out his window. Couldn’t be, he thought. But he checked a picture he’d taken the day before, and, sure enough, there had been no building in that spot.

    The corn close to town was covered in construction dust. “I’ve never seen anything like that in my whole life,” says Krčo. Today, though, the corn is gone, covered instead in hotels, museums, and shopping centers.

    5
    Before FAST, few large structures existed in this part of China. Feature China/Barcroft Media/Getty Images

    6
    Now, they abound. Liu Xu/Xinhua/Getty Images

    At a press conference in March 2017, Guizhou’s governor declared that the province would build 10,000 kilometers of new highway by 2020, in addition to completing 17 airports and 4,000 kilometers of high-speed train lines. That’s partly to accommodate the hundreds of thousands of people the province expects to relocate here permanently, as well as the tourists. While just those 3,000 people per day will get to visit the telescope itself, there’s no cap on how many can sojourn in Astronomy Town; the deputy director of Guizhou’s reform and development commission, according to China Daily, said it would be “a main astronomical tourism zone worldwide.” “The town has grown incredibly over the last couple of years due to tourism development,” says Krčo. “This has impacted our RFI environment, but not yet to a point where it is unmanageable.”

    Krčo says that geography protects FAST against much of that human interference. “There are a great many mountains between the telescope and the town,” says Krčo. The land blocks the waves, which you’ve seen yourself if you’ve ever tried to pick up NPR in a canyon. But even though the waves can’t go directly into the telescope, Krčo says the team still sees their echoes, reflections beamed down from the atmosphere.

    “People at the visitors’ center have been using cameras and whatnot, and we can see the RFI from that,” he said last November (enforcement seems to have ramped up since then). “During the daytime,” he adds, “our RFI is much worse than nighttime,” largely due to engineers working onsite (that should improve once commissioning is over). But the tourist traps aren’t run and weren’t developed by FAST staff but by various governmental arms—so FAST, really, has no control over what they do.

    The global radio astronomy community has concerns. “I’m absolutely sure that if people are going to bring their toys, then there’s going to be RFI,” says Carla Beaudet, an RFI engineer at Green Bank Observatory, who spends her career trying to help humans see the radio sky despite themselves. Green Bank itself sits in the middle of a strict radio protection zone with a radius of 10 miles, in which there’s no Wi-Fi or even microwaves.

    There are other ways of dealing with RFI—and Krčo says FAST has a permanent team of engineers dedicated to dealing with interference. One solution, which can pick up the strongest contamination, is a small antenna mounted to one of FAST’s support towers. “The idea is that it will observe the same RFI as the big dish,” says Krčo. “Then, in principle, we can remove the RFI from the data in real time.”

    At other telescopes, astronomers are developing machine-learning algorithms that could identify, extract, and compensate for dirty data. All telescopes, after all, have human contamination, even the ones without malls next door. You can’t stop a communications satellite from passing overhead, or a radar beam from bouncing the wrong way across the mountains. And while you can decide not to build a tourist town in the first place, you probably can’t stop a tidal wave of construction once it’s crested.

    In their free evenings at the Radio Astronomy Forum, Stierwalt and the other astronomers wandered through the development. Across from their luxury hotel, workers were constructing a huge mall. It was just scaffolding then, but sparks flew from tools every night. “So the joke was, ‘I wonder if we’ll be able to go shopping at the mall by the end of our trip,’” says Stierwalt.

    At the end of the conference, Stierwalt rode a bus back to the airport, awed by what she’d seen. The karst hills, dipping and rising out the window, looked like those in Puerto Rico, where she had used the 300-meter Arecibo telescope for weeks at a time during her graduate research.

    When she tried to check in for her flight, she didn’t know where to go, what to do. An agent wrote her passport number down wrong.

    A young Chinese man, an astronomer, saw her struggle and approached her. “I’m on your flight,” he said, “and I’ll make sure you get on it.”

    In line after line, they started talking about other things—life, science. “I was describing the astronomy landscape for me,” she says. Never enough jobs, never enough research money, necessary competition with your friends. “For him, it’s very different.”

    He lives in a country that wants to accrete a community of radio astronomers, not winnow one down. A country that wants to support (and promote) ambitious telescopes, rather than defund the ones it has. China isn’t just trying to build a tourist economy around its telescope—it’s also trying to build a scientific culture around radio astronomy.

    That latter part seems like a safe bet. But the first is still uncertain. So is how the tourist economy will affect—for better or worse—FAST’s scientific payoff. “Much like their CRAFTS survey is trying to make everyone happy—all the different kinds of radio astronomers—this will be a true test of ‘Can you make everyone happy?’” says Stierwalt. “Can you make a prosperous astronomy town right next to a telescope that doesn’t want you to be using your phone or your microwave?”

    Right now, nobody knows. But if the speed of everything else in Guizhou is any indication, we’ll all find out fast.

    [* I had previously read, which I cannot any longer back up, that FAST was built in a fortunately found an empty natural bowl in the land. If anyone can correct me, please do]

    See the full article here .

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  • richardmitnick 1:33 pm on August 11, 2018 Permalink | Reply
    Tags: , , , , , Quasars are now known to be supermassive black holes feeding on surrounding gas not stars., , WIRED, Zwicky Transit Facility at California’s Palomar Observatory   

    From Wired: “Star-Swallowing Black Holes Reveal Secrets in Exotic Light Shows” 

    Wired logo

    From Wired

    08.11.18
    Joshua Sokol

    Black holes, befitting their name and general vibe, are hard to find and harder to study. You can eavesdrop on small ones from the gravitational waves that echo through space when they collide—but that technique is new, and still rare. You can produce laborious maps of stars flitting around the black hole at the center of the Milky Way or nearby galaxies. Or you can watch them gulp down gas clouds, which emit radiation as they fall.

    Now researchers have a new option. They’ve begun corralling ultrabright flashes called tidal disruption events (TDEs), which occur when a large black hole seizes a passing star, shreds it in two and devours much of it with the appetite of a bear snagging a salmon. “To me, it’s sort of like science fiction,” said Enrico Ramirez-Ruiz, an astrophysicist at University of California, Santa Cruz, and the Niels Bohr Institute.

    During the past few years, though, the study of TDEs has transformed from science fiction to a sleepy cottage industry, and now into something more like a bustling tech startup.

    Automated wide-field telescopes that can pan across thousands of galaxies each night have uncovered about two dozen TDEs. Included in these discoveries are some bizarre and long-sought members of the TDE zoo. In June, a study in the journal Nature described an outburst of X-ray light in a cluster of faraway stars that astronomers interpreted as a midsized black hole swallowing a star. That same month, another group announced in Science that they had discovered what may be brightest ever TDE, one that illuminated faint gas at the heart of a pair of merging galaxies.

    These discoveries have taken place as our understanding of what’s really happening during a TDE comes into sharper focus. At the end of May, a group of astrophysicists proposed [The Astrophysical Journal Letters] a new theoretical model for how TDEs work. The model can explain why different TDEs can appear to behave differently, even though the underlying physics is presumably the same.

    Astronomers hope that decoding these exotic light shows will let them conduct a black hole census. Tidal disruptions expose the masses, spins and sheer numbers of black holes in the universe, the vast majority of which would be otherwise invisible. Theorists are hungry, for example, to see if TDEs might unveil any intermediate-mass black holes with weights between the two known black hole classes: star-size black holes that weigh a few times more than the sun, and the million- and billion-solar-mass behemoths that haunt the cores of galaxies. The Nature paper claims they may already have.


    A numerical simulation of the core of a star as it’s being consumed by a black hole. Video by Guillochon and Ramirez-Ruiz

    Researchers have also started to use TDEs to probe the fundamental physics of black holes. They can be used to test whether black holes always have event horizons—curtains beyond which nothing can return—as Einstein’s theory of general relativity predicts.

    Meanwhile, many more observations are on the way. The rate of new TDEs, now about one or two per year, could jump up by an order of magnitude [Stellar Tidal Disruption Events in General Relativity]even by the end of this year because of the Zwicky Transient Facility, which started scanning the sky over California’s Palomar Observatory in March.

    Zwicky Transit Facility at California’s Palomar Observatory schematic

    Zwicky Transit Facility at California’s Palomar Observatory

    And with the addition of planned observatories, it may increase perhaps another order of magnitude in the years to come.Researchers have also started to use TDEs to probe the fundamental physics of black holes. They can be used to test whether black holes always have event horizons—curtains beyond which nothing can return—as Einstein’s theory of general relativity predicts.

    “The field has really blossomed,” said Suvi Gezari at the University of Maryland, one of the few stubborn pioneers who staked their careers on TDEs during leaner years. She now leads the Zwicky Transient Facility’s TDE-hunting team, which has already snagged unpublished candidates in its opening months, she said. “Now people are really digging in.”

    Searching for Star-Taffy

    In 1975, the British physicist Jack Hills first dreamed up a black-hole-eats-star scenario as a way to explain what powers quasars—superbright points of light from the distant universe. (Quasars are now known to be supermassive black holes feeding on surrounding gas, not stars.) But in 1988, the British cosmologist Martin Rees realized [Nature]that black holes snacking on a star would exhibit a sharp flare, not a steady glow. Looking for such flares could let astronomers find and study the black holes themselves, he argued.

    Nothing that fit the bill turned up until the late 1990s. That’s when Stefanie Komossa, at the time a graduate student at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, found massive X-ray flares [Discovery of a giant and luminous X-ray outburst from the optically inactive galaxy pair RXJ1242.6-1119] from the centers of distant galaxies that brightened and dimmed according to the Rees predictions.

    The astronomical community responded to these discoveries—based on just a few data points—with caution. Then in the mid-2000s, Gezari, then beginning a postdoc at the California Institute of Technology, searched for and discovered her own handful of TDE candidates. She looked for flashes of ultraviolet light, not X-rays as Komossa had. “In the old days,” Gezari said, “I was just trying to convince people that any of our discoveries were actually due to a tidal disruption.”

    Soon, though, she had something to sway even the doubters. In 2010, Gezari discovered an especially clear flare, rising and falling as modelers predicted. She published it in Nature in 2012, catching other astronomers’ attention. In the years since, large surveys in optical light, sifting through the sky for changes in brightness, have taken over the hunt. And like Komossa’s and Gezari’s TDEs, which had both been fished out of missions designed to look for other things, the newest batch showed up as bycatch. “It was, oh, why didn’t we think about looking for these?” said Christopher Kochanek, an astrophysicist at Ohio State University who works on a project designed to search for supernovas [ASAS-SN OSU All-Sky Automated Survey for Supernovae].

    Now, with a growing number of TDEs in hand, astrophysicists are within arm’s reach of Rees’s original goal: pinpointing and studying gargantuan black holes. But they still need to learn to interpret these events, divining their basic physics. Unexpectedly, the known TDEs fall into separate classes [A unified model for tidal disruption events]. Some seem to emit mostly ultraviolet and optical light, as if from gas heated to tens of thousands of degrees. Others glow fiercely with X-rays, suggesting temperatures an order of magnitude higher. Yet presumably they all have the same basic physical root.

    To be disrupted, an unlucky star must venture close enough to a black hole that gravitational tides exceed the internal gravity that binds the star together. In other words, the difference in the black hole’s gravitational pull on the near and far sides of the star, along with the inertial pull as the star swings around the black hole, stretches the star out into a stream. “Basically it spaghettifies,” said James Guillochon, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics.

    The outer half of the star escapes away into space. But the inner half—that dense stream of star-taffy—swirls into the black hole, heating up and releasing huge sums of energy that radiate across the universe.

    With this general mechanism understood, researchers had trouble understanding why individual TDEs can look so distinct. One longstanding idea appeals to different phases of the star-eating process. As the star flesh gets initially torn away and stretched into a stream, it might ricochet around the black hole and slam into its own tail. This process might heat the tail up to ultraviolet-producing temperatures—but not hotter. Then later—after a few months or a year—the star would settle into an accretion disk, a fat bagel of spinning gas that theories predict should be hot enough to emit X-rays.

    See the full article here .


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    Please help promote STEM in your local schools.

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  • richardmitnick 2:41 pm on July 22, 2018 Permalink | Reply
    Tags: , , , , , , , , Sau Lan Wu, WIRED,   

    From LHC at CERN and University of Wisconsin Madison via WIRED and Quanta: Women in STEM “Meet the Woman Who Rocked Particle Physics—Three Times” Sau Lan Wu 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead

    CERN

    U Wisconsin

    via

    Wired logo

    WIRED

    originated at

    Quanta Magazine
    Quanta Magazine

    7.22.18
    Joshua Roebke

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    Sau Lan Wu at CERN, the laboratory near Geneva that houses the Large Hadron Collider. The mural depicts the detector she and her collaborators used to discover the Higgs boson. Thi My Lien Nguyen/Quanta Magazine

    In 1963, Maria Goeppert Mayer won the Nobel Prize in physics for describing the layered, shell-like structures of atomic nuclei. No woman has won since.

    One of the many women who, in a different world, might have won the physics prize in the intervening 55 years is Sau Lan Wu. Wu is the Enrico Fermi Distinguished Professor of Physics at the University of Wisconsin, Madison, and an experimentalist at CERN, the laboratory near Geneva that houses the Large Hadron Collider.

    LHC

    CERN map


    CERN LHC Tunnel

    CERN LHC particles

    Wu’s name appears on more than 1,000 papers in high-energy physics, and she has contributed to a half-dozen of the most important experiments in her field over the past 50 years. She has even realized the improbable goal she set for herself as a young researcher: to make at least three major discoveries.

    Wu was an integral member of one of the two groups that observed the J/psi particle, which heralded the existence of a fourth kind of quark, now called the charm. The discovery, in 1974, was known as the November Revolution, a coup that led to the establishment of the Standard Model of particle physics.

    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.


    Standard Model of Particle Physics from Symmetry Magazine

    Later in the 1970s, Wu did much of the math and analysis to discern the three “jets” of energy flying away from particle collisions that signaled the existence of gluons—particles that mediate the strong force holding protons and neutrons together. This was the first observation of particles that communicate a force since scientists recognized photons of light as the carriers of electromagnetism. Wu later became one of the group leaders for the ATLAS experiment, one of the two collaborations at the Large Hadron Collider that discovered the Higgs boson in 2012, filling in the final piece of the Standard Model.

    CERN ATLAS Higgs Event


    CERN/ATLAS detector

    She continues to search for new particles that would transcend the Standard Model and push physics forward.

    Sau Lan Wu was born in occupied Hong Kong during World War II. Her mother was the sixth concubine to a wealthy businessman who abandoned them and her younger brother when Wu was a child. She grew up in abject poverty, sleeping alone in a space behind a rice shop. Her mother was illiterate, but she urged her daughter to pursue an education and become independent of volatile men.

    Wu graduated from a government school in Hong Kong and applied to 50 universities in the United States. She received a scholarship to attend Vassar College and arrived with $40 to her name.

    Although she originally intended to become an artist, she was inspired to study physics after reading a biography of Marie Curie. She worked on experiments during consecutive summers at Brookhaven National Laboratory on Long Island, and she attended graduate school at Harvard University. She was the only woman in her cohort and was barred from entering the male dormitories to join the study groups that met there. She has labored since then to make a space for everyone in physics, mentoring more than 60 men and women through their doctorates.

    Quanta Magazine joined Sau Lan Wu on a gray couch in sunny Cleveland in early June. She had just delivered an invited lecture about the discovery of gluons at a symposium to honor the 50th birthday of the Standard Model. The interview has been condensed and edited for clarity.

    2
    3
    Wu’s office at CERN is decorated with mementos and photos, including one of her and her husband, Tai Tsun Wu, a professor of theoretical physics at Harvard.
    Thi My Lien Nguyen/Quanta Magazine

    You work on the largest experiments in the world, mentor dozens of students, and travel back and forth between Madison and Geneva. What is a normal day like for you?

    Very tiring! In principle, I am full-time at CERN, but I do go to Madison fairly often. So I do travel a lot.

    How do you manage it all?

    Well, I think the key is that I am totally devoted. My husband, Tai Tsun Wu, is also a professor, in theoretical physics at Harvard. Right now, he’s working even harder than me, which is hard to imagine. He’s doing a calculation about the Higgs boson decay that is very difficult. But I encourage him to work hard, because it’s good for your mental state when you are older. That’s why I work so hard, too.

    Of all the discoveries you were involved in, do you have a favorite?

    Discovering the gluon was a fantastic time. I was just a second- or third-year assistant professor. And I was so happy. That’s because I was the baby, the youngest of all the key members of the collaboration.

    The gluon was the first force-carrying particle discovered since the photon. The W and Z bosons, which carry the weak force, were discovered a few years later, and the researchers who found them won a Nobel Prize. Why was no prize awarded for the discovery of the gluon?

    Well, you are going to have to ask the Nobel committee that. [Laughs.] I can tell you what I think, though. Only three people can win a Nobel Prize. And there were three other physicists on the experiment with me who were more senior than I was. They treated me very well. But I pushed the idea of searching for the gluon right away, and I did the calculations. I didn’t even talk to theorists. Although I married a theorist, I never really paid attention to what the theorists told me to do.

    How did you wind up being the one to do those calculations?

    If you want to be successful, you have to be fast. But you also have to be first. So I did the calculations to make sure that as soon as a new collider at at DESY [the German Electron Synchrotron] turned on in Hamburg we could see the gluon and recognize its signal of three jets of particles.

    DESY Helmholtz Centres & Networks: DESY’s synchrotron radiation source: the PETRA III storage ring (in orange) with the three experimental halls (in blue) in 2015.

    We were not so sure in those days that the signal for the gluon would be clear-cut, because the concept of jets had only been introduced a couple of years earlier, but this seemed to be the only way to discover gluons.

    You were also involved in discovering the Higgs boson, the particle in the Standard Model that gives many other particles their masses. How was that experiment different from the others that you were part of?

    I worked a lot more and a lot longer to discover the Higgs than I have on anything else. I worked for over 30 years, doing one experiment after another. I think I contributed a lot to that discovery. But the ATLAS collaboration at CERN is so large that you can’t even talk about your individual contribution. There are 3,000 people who built and worked on our experiment [including 600 scientists at Brookhaven National Lab, NY, USA]. How can anyone claim anything? In the old days, life was easier.

    Has it gotten any easier to be a woman in physics than when you started?

    Not for me. But for younger women, yes. There is a trend among funding agencies and institutions to encourage younger women, which I think is great. But for someone like me it is harder. I went through a very difficult time. And now that I am established others say: Why should we treat you any differently?

    Who were some of your mentors when you were a young researcher?

    Bjørn Wiik really helped me when I was looking for the gluon at DESY.

    How so?

    Well, when I started at the University of Wisconsin, I was looking for a new project. I was interested in doing electron-positron collisions, which could give the clearest indication of a gluon. So I went to talk to another professor at Wisconsin who did these kinds of experiments at SLAC, the lab at Stanford. But he was not interested in working with me.

    So I tried to join a project at the new electron-positron collider at DESY. I wanted to join the JADE experiment [abbreviated from the nations that developed the detector: Japan, Germany (Deutschland) and England]. I had some friends working there, so I went to Germany and I was all set to join them. But then I heard that no one had told a big professor in the group about me, so I called him up. He said, “I am not sure if I can take you, and I am going on vacation for a month. I’ll phone you when I get back.” I was really sad because I was already in Germany at DESY.

    But then I ran into Bjørn Wiik, who led a different experiment called TASSO, and he said, “What are you doing here?” I said, “I tried to join JADE, but they turned me down.” He said, “Come and talk to me.” He accepted me the very next day.

    4
    TASSO detector at PETRA at DESY

    And the thing is, JADE later broke their chamber, and they could not have observed the three-jet signal for gluons when we observed it first at TASSO. So I have learned that if something does not work out for you in life, something else will.

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    Wu and Bjørn Wiik in 1978, in the electronic control room of the TASSO experiment at the German Electron Synchrotron in Hamburg, Germany. Dr. Ulrich Kötz

    You certainly turned that negative into a positive.

    Yes. The same thing happened when I left Hong Kong to attend college in the US. I applied to 50 universities after I went through a catalog at the American consulate. I wrote in every application, “I need a full scholarship and room and board,” because I had no money. Four universities replied. Three of them turned me down. Vassar was the only American college that accepted me. And it turns out, it was the best college of all the ones I applied to.

    If you persist, something good is bound to happen. My philosophy is that you have to work hard and have good judgment. But you also have to have luck.

    I know this is an unfair question, because no one ever asks men, even though we should, but how can society inspire more women to study physics or consider it as a career?

    Well, I can only say something about my field, experimental high-energy physics. I think my field is very hard for women. I think partially it’s the problem of family.

    My husband and I did not live together for 10 years, except during the summers. And I gave up having children. When I was considering having children, it was around the time when I was up for tenure and a grant. I feared I would lose both if I got pregnant. I was less worried about actually having children than I was about walking into my department or a meeting while pregnant. So it’s very, very hard for families.

    I think it still can be.

    Yeah, but for the younger generation it’s different. Nowadays, a department looks good if it supports women. I don’t mean that departments are deliberately doing that only to look better, but they no longer actively fight against women. It’s still hard, though. Especially in experimental high-energy physics. I think there is so much traveling that it makes having a family or a life difficult. Theory is much easier.

    You have done so much to help establish the Standard Model of particle physics. What do you like about it? What do you not like?

    It’s just amazing that the Standard Model works as well as it does. I like that every time we try to search for something that is not accounted for in the Standard Model, we do not find it, because the Standard Model says we shouldn’t.

    But back in my day, there was so much that we had yet to discover and establish. The problem now is that everything fits together so beautifully and the Model is so well confirmed. That’s why I miss the time of the J/psi discovery. Nobody expected that, and nobody really had a clue what it was.

    But maybe those days of surprise aren’t over.

    We know that the Standard Model is an incomplete description of nature. It doesn’t account for gravity, the masses of neutrinos, or dark matter—the invisible substance that seems to make up six-sevenths of the universe’s mass. Do you have a favorite idea for what lies beyond the Standard Model?

    Well, right now I am searching for the particles that make up dark matter. The only thing is, I am committed to working at the Large Hadron Collider at CERN. But a collider may or may not be the best place to look for dark matter. It’s out there in the galaxies, but we don’t see it here on Earth.

    Still, I am going to try. If dark matter has any interactions with the known particles, it can be produced via collisions at the LHC. But weakly interacting dark matter would not leave a visible signature in our detector at ATLAS, so we have to intuit its existence from what we actually see. Right now, I am concentrating on finding hints of dark matter in the form of missing energy and momentum in a collision that produces a single Higgs boson.

    What else have you been working on?What else have you been working on?

    Our most important task is to understand the properties of the Higgs boson, which is a completely new kind of particle. The Higgs is more symmetric than any other particle we know about; it’s the first particle that we have discovered without any spin. My group and I were major contributors to the very recent measurement of Higgs bosons interacting with top quarks. That observation was extremely challenging. We examined five years of collision data, and my team worked intensively on advanced machine-learning techniques and statistics.

    In addition to studying the Higgs and searching for dark matter, my group and I also contributed to the silicon pixel detector, to the trigger system [that identifies potentially interesting collisions], and to the computing system in the ATLAS detector. We are now improving these during the shutdown and upgrade of the LHC. We are also very excited about the near future, because we plan to start using quantum computing to do our data analysis.

    6
    Wu at CERN. Thi My Lien Nguyen/Quanta Magazine

    Do you have any advice for young physicists just starting their careers?

    Some of the young experimentalists today are a bit too conservative. In other words, they are afraid to do something that is not in the mainstream. They fear doing something risky and not getting a result. I don’t blame them. It’s the way the culture is. My advice to them is to figure out what the most important experiments are and then be persistent. Good experiments always take time.

    But not everyone gets to take that time.

    Right. Young students don’t always have the freedom to be very innovative, unless they can do it in a very short amount of time and be successful. They don’t always get to be patient and just explore. They need to be recognized by their collaborators. They need people to write them letters of recommendation.

    The only thing that you can do is work hard. But I also tell my students, “Communicate. Don’t close yourselves off. Try to come up with good ideas on your own but also in groups. Try to innovate. Nothing will be easy. But it is all worth it to discover something new.”

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    In achievement and prestige, the University of Wisconsin–Madison has long been recognized as one of America’s great universities. A public, land-grant institution, UW–Madison offers a complete spectrum of liberal arts studies, professional programs and student activities. Spanning 936 acres along the southern shore of Lake Mendota, the campus is located in the city of Madison.

     
  • richardmitnick 4:19 pm on June 19, 2018 Permalink | Reply
    Tags: , Sunway TaihuLight China, , Why the US and China's brutal supercomputer war matters, WIRED   

    From Wired: “Why the US and China’s brutal supercomputer war matters” 

    Wired logo

    Wired

    19 June 2018
    Chris Stokel-Walker

    ORNL IBM AC922 SUMMIT supercomputer. Credit: Carlos Jones, Oak Ridge National Laboratory/U.S. Dept. of Energy

    Thought global arms races are all about ballistic missiles, space or nuclear development? Think again: the new diplomatic frontline is over processing power and computer chips.
    Multi-million dollar projects to eke out an advantage in processing power aren’t really about science, they’re an exercise in soft power.

    A major shift has taken place, with a new claimant to the crown of world’s fastest supercomputer. IBM’s Summit at Oak Ridge National Laboratory in Tennessee uses Power9 CPUs and NVIDIA Tesla V100 GPUs and has 4,068 servers powered by ten petabytes of memory working concurrently to process 200,000 trillion calculations per second – 200 petaflops. That’s a lot of numbers – and here’s one more. Summit’s processing power is 117 petaflops more than the previous record-holder, China’s TaihuLight.

    Sunway TaihuLight, China, US News

    While it may seem significant, it’s actually largely symbolic, says Andrew Jones of the Numerical Algorithms Group, a high-performance computing consultancy. “I put no value on being twice as fast or 20 per cent faster other than bragging rights.”

    That’s not to say that supercomputers don’t matter. They are “being driven by science”, says Jack Dongarra, a computer science professor at the University of Tennessee and the compiler of the world’s top 500 supercomputer list. And science is driven today by computer simulation, he adds – with high-powered computers crucial to carry out those tests.

    Supercomputers can crunch data far faster and more easily than regular computers, making them ideal for handling big data – from cybersecurity to medical informatics to astronomy. “We could quite easily go another four or five orders of magnitude and still find scientific and business reasons to benefit from it,” says Jones.

    Oak Ridge, where Summit is housed, is already soliciting bids for a project called Coral II, the successor to the Coral project which resulted in the Summit supercomputer. The Coral II will involve three separate hardware systems, each of which has a price tag of $600 million, says Dongarra. The goal? To build a supercomputer capable of calculating at a rate of exaflops – five times faster than Summit.

    While they are faster and more powerful, supercomputers are actually not much different from the hardware we interact with on a daily basis, says Jones. “The basic components are the same as a standard server,” he says. But because of their scale, and the complexity involved in programming them to process information as a single, co-ordinated unit, supercomputer projects require significant financial outlay to build, and political support to attract that funding.

    That political involvement transforms them from a simple computational tool into a way of exercising soft power and stoking intercontinental rivalries.

    With Summit, the US has wrested back the title of the world’s most powerful supercomputer for the first time since 2012 – though it still languishes behind China in terms of overall processing power. China is the home of 202 of the 500 most powerful supercomputers, having overtaken the US in November 2017.

    “What’s quite striking is that in 2001 there were no Chinese machines that’d be considered a supercomputer, and today they dominate,” explains Dongarra. The sudden surge of supercomputers in China over the last two decades is an indication of significant investment, says Jones. “It’s more a reflection of who’s got their lobbying sorted than anything else,” he adds.

    Recently, the Chinese leadership has been drifting away “from an aspirational ‘catch-up with the west’ mentality to aspiring to be world class and to lead,” says Jonathan Sullivan, director of the China Policy Institute at the University of Nottingham. “These achievements like the longest bridge, biggest dam and most powerful supercomputer aren’t just practical solutions, they also have symbolic meaning,” he adds.

    Or putting it differently: bragging rights matter enormously to whoever’s on top.

    [TaihuLight is about 2 years old. The Chinese supercomputer people have not been sitting on their hands. They knew this was coming. We will see how long Summit is at the top.]

    See the full article here .


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    Please help promote STEM in your local schools.

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  • richardmitnick 3:27 pm on April 6, 2018 Permalink | Reply
    Tags: , , , , , , Virginia Trimble, WIRED,   

    From UCSC and UC Irvine via WIRED: Women in STEM – “The Woman Who Knows Everything About the Universe” Virginia Trimble 

    UC Santa Cruz

    UC Santa Cruz

    UC Irvine bloc

    UC Irvine

    WIRED

    1
    For 16 years, Virginia Trimble read every astronomy paper in 23 journals. Now, her review papers are part of the canon. Universitat de València.

    In 1965, physicist Richard Feynman was busy.

    Richard Feynman © Open University

    He was busy winning the Nobel Prize, and he was busy learning to draw. One day during that productive time in his life, he saw astrophysics student Virginia Trimble striding across Caltech’s campus and thought, There’s a good model.

    Soon, she was posing for him a couple Tuesdays a month, in exchange for $5.50 each session and a lot of physics talk. She was studying a nebula, and he was, sometimes, sharing anecdotes that would later appear in one of his books, which featured everything from his bongo playing to his work on the Manhattan Project. Treatment of women in professional and academic situations has changed—and significantly so—since those sixties-California-campus days. Trimble was a student at a university that enrolled few women, in a field that enlisted few women. But her experience at Caltech wasn’t limited to sidelining model gigs. Those early days of learning and research were the beginning of a five-decade career that has turned Trimble into a powerhouse of astronomy.

    I first encountered Trimble’s work when I was an undergraduate astrophysics major. On the first day of seminar, my professor handed out a 101-page stack of paper. Flipping through its 13 sections, he explained that Trimble trawled the scientific journals and collated the year’s cosmic progress into a tome like this one. It wasn’t just a review paper laying out the state of atmospheric studies of Jupiter, or asteroid hunting, or massive star formation. It was all of everything important that had happened the previous year in astronomy—broad, comprehensive, and utterly unusual. Most unusual of all was that it contained jokes.

    Today, new technologies promise to synthesize masses of publication data for scientists. But before artificial intelligence even tried, astronomers had Trimble, who wrote these comprehensive articles every year. For 16 years, she devoted her mind to this task of curation, contextualization, and commentary. And throughout her career, she has largely eschewed long-term research with fancy telescopes, competitive funding, and approving nods from university administrators. Refusing narrow focus, she has gone solo on most of her 850 publications, focusing as much on the nature of doing astronomy as studying the universe itself.

    “I just asked questions,” she says, “and sometimes found a way to answer them.” That’s business as usual for Trimble, who has spent much of her career branching off from the already thin bough of bushwhacking female astronomers.

    When Trimble enrolled at UCLA in the 1960s, she wanted to major in archaeology. But the school only offered that field of study to graduate students. Right there in the A section of the catalog, though, was “astronomy,” a topic that her father informed her she’d always been interested in.

    So she enrolled as an astronomy student, living at home while attending the university’s gifted program. Which she was—gifted. In a 1962 LIFE package about California’s educational system, a journalist profiled Trimble for a piece called Behind a Lovely Face, a 180 I.Q. The title acted surprised that a pretty lady might also have a productive brain—but Trimble quickly made it clear that people should cease to be surprised at her smarts.

    Trimble’s father was right, and she felt drawn to the mysteries of the universe. After she finished her undergraduate degree, Trimble was accepted to a PhD program at Caltech. “It was only later that I looked in their catalog and saw that women were only admitted under exceptional circumstances,” she says, “exceptional” usually meaning “married to a male Caltech admittee.” There, Trimble studied the Crab Nebula, the dust, gas, and plasma sent speeding into space during a supernova explosion whose light reached Earth in 1054.

    Supernova remnant Crab nebula. NASA/ESA Hubble

    To work on this project, she applied for time at Palomar Observatory, an iconic be-domed telescope east of San Diego.


    Caltech Palomar Observatory, located in San Diego County, California, US, at 1,712 m (5,617 ft)

    She was only the third woman to use the telescope, and only the second to actually be granted her own time on it (Vera Rubin, a dark-matter pioneer, was the first).

    Vera Rubin measuring spectra (Emilio Segre Visual Archives AIP SPL)

    Astronomer Vera Rubin at the Lowell Observatory in 1965. (The Carnegie Institution for Science)

    The nebula’s contents are still, these centuries later, lit. They beam out bright radiation across a spectrum of wavelengths. Today, scientists know that a pulsar—the corpse of a massive star, as dense as an atomic nucleus and the size of a city, spinning 30 times a second—lurks at the center and energizes it. But back when Trimble was doing her dissertation, pulsars were just being discovered, and no one knew the Crab hosted one. “It was quite a mystery what kept the thing as bright as it is now,” she says.

    For her doctoral work, she measured the motions of the nebula’s filaments, and found, among other things, that the gas had sped up its flight from the center of the explosion since that explosion had happened (weird!) and that it was around 6,500 light-years away. Discovery was all right, but its details—so many photographic plates, so many similar, tedious observations—wasn’t the most fun. She sang, danced, on the side, to liven life up. But did she enjoy the telescope part? I ask. Going to a mountaintop, commanding a large instrument, gathering her own data about the universe with her own hands?

    “Noooooo,” she says. “It was cold, and I hate being cold.”

    Trimble soon realized she didn’t want to look at the Crab Nebula—or at supernova remnants more generally, or at anything, really—for the rest of her life. She preferred independence to teams. She didn’t want to hand a bunch of her grant money over to UC Irvine, where she became a tenured astronomer. So, instead of all that, she started publishing papers that took an aerial view of the field of astronomy.

    Like any scientist, she liked to wonder. And, when people began asking her to give big talks at conferences, she started wondering more about how science gets made, and why, and by whom. “I always figured this was my opportunity to say something that might not otherwise not get said,” she says. So instead of, say, summarizing the conference’s topic, she analyzed big-picture questions: How did this sub-field become interesting? Why are we worrying about this particular research subject now? Whose work did we leave out at this meeting?

    She wondered whether it paid to go to a good graduate school, in terms of career advancement (it did). She wondered which telescopes birthed the most papers, and found that a huge number of papers came from non-celebrity instruments. She wondered about the narrative arc that led to scientific consensus, and wrote a paper that tracked the progress of different scientific debates—over things like the nature of Jupiter’s Great Red Spot and the existence of dark matter.

    And then there was that time she trolled her colleagues, publishing this paper suggesting that the blue star next to a suspected black hole—the first real black hole candidate—was smaller than people thought. If that was true, it would also mean the black hole was smaller. Too small, in fact, to be a black hole at all. Two different groups instantly set out to prove her incorrect.

    “I knew it was wrong when I suggested doing it,” she says. “It was a way to get people to go out and do observations.”

    Much of her work seems to demand that astronomers think differently, perhaps situate themselves a little more, rather than imagining that their research is standalone, decoupled from larger culture. She’s recently been working, for instance, on a series about how World War I influenced the development of general relativity, and on a chapter for a book about people who maybe should have won the Nobel Prize and didn’t.

    “Is it fun?” I ask.

    “It’s certainly fun,” she says, “or I wouldn’t do it.”

    If Trimble was asking questions other astronomers didn’t think of, or at least didn’t investigate, it may have been because she knew so much more than them. Each year starting in 1991, she read every article—every one—in 23 journals. “I quickly decided whether this was anything I would ever want to know about again,” she says. If it was, it got a line in her notebook (two lines if it was super interesting). When it came time to write, she’d go back to her notebook, cull a bit, organize the entries into topics, and then write what was essentially a historical record of that annum, with the year’s accumulated cosmic knowledge.

    Here’s what she liked best about it: “I got to tell these nasty jokes,” she says. Like this one, from the 2005 paper that I read in college: “If every galaxy has [a black hole], why do people talk about them so much? Well, the same could probably be said about human private parts, which also have in common with black holes a central location and, as a rule, concealing material around.”

    But around 2007, editorial interest in the review declined, around the same time that printing and reading journal articles on paper went out of fashion. “I can’t read 6,000 papers online,” she says. Staring at a screen that long is intense. “I start seeing jagged lightning patterns,” she says.

    Now, no single person knows what all the world’s astronomers do all day. And it would be hard for a younger scientist to take Trimble’s task on again: Academic science doesn’t value broad-mindedness, in practice. It’s a publish or perish world full of big collaborations, in which most people nest in their niche of the knowledge-creation establishment.

    But despite that, the larger astronomical community seems to agree that Trimble’s contributions were valuable. Trimble has been a vice president within the International Astronomical Union and the vice president of the American Astronomical Society, which also gave her the George Van Biesbroeck prize, “for long-term extraordinary or unselfish service to astronomy.” The American Association of Physics Teachers gave her its Klopsteg Memorial Lecture Award, which “recognizes outstanding communication of the excitement of contemporary physics to the general public.”

    But, perhaps most fittingly, the International Astronomical Union recently named an asteroid after her. Now called 9271Trimble, the space rock travels solo, within a belt of others like itself.

    When I called to interview Trimble for this article, she asked if I received the 40 or so scanned pages she sent—the beginning of her memoir. In it, she recounts those posing sessions at Caltech. Feynman “didn’t like silence,” Trimble wrote, so he talked, and sometimes listened. “Heard many of the anecdotes that appear in Surely You’re Joking,” she continued, referring to Feynman’s most-famous book, “and some that don’t.”

    The memoir is obviously unfinished, she says—dozens of pages and not even past her early years. “I got bored,” she explains. “I just got bored.” It was never, after all, Trimble’s style to stick to one topic.

    See the full article here .

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    Since 1965, the University of California, Irvine has combined the strengths of a major research university with the bounty of an incomparable Southern California location. UCI’s unyielding commitment to rigorous academics, cutting-edge research, and leadership and character development makes the campus a driving force for innovation and discovery that serves our local, national and global communities in many ways.

    With more than 29,000 undergraduate and graduate students, 1,100 faculty and 9,400 staff, UCI is among the most dynamic campuses in the University of California system. Increasingly a first-choice campus for students, UCI ranks among the top 10 U.S. universities in the number of undergraduate applications and continues to admit freshmen with highly competitive academic profiles.

    UCI fosters the rigorous expansion and creation of knowledge through quality education. Graduates are equipped with the tools of analysis, expression and cultural understanding necessary for leadership in today’s world.

    Consistently ranked among the nation’s best universities – public and private – UCI excels in a broad range of fields, garnering national recognition for many schools, departments and programs. Times Higher Education ranked UCI No. 1 among universities in the U.S. under 50 years old. Three UCI researchers have won Nobel Prizes – two in chemistry and one in physics.

    The university is noted for its top-rated research and graduate programs, extensive commitment to undergraduate education, and growing number of professional schools and programs of academic and social significance. Recent additions include highly successful programs in public health, pharmaceutical sciences and nursing science; an expanding education school; and a law school already ranked among the nation’s top 10 for its scholarly impact.

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    UCO Lick Shane Telescope
    UCO Lick Shane Telescope interior
    Shane Telescope at UCO Lick Observatory, UCSC

    Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

    Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

    UC Santa Cruz campus
    The University of California, Santa Cruz, opened in 1965 and grew, one college at a time, to its current (2008-09) enrollment of more than 16,000 students. Undergraduates pursue more than 60 majors supervised by divisional deans of humanities, physical & biological sciences, social sciences, and arts. Graduate students work toward graduate certificates, master’s degrees, or doctoral degrees in more than 30 academic fields under the supervision of the divisional and graduate deans. The dean of the Jack Baskin School of Engineering oversees the campus’s undergraduate and graduate engineering programs.

    UCSC is the home base for the Lick Observatory.

    Lick Observatory's Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building
    Lick Observatory’s Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building

    Search for extraterrestrial intelligence expands at Lick Observatory
    New instrument scans the sky for pulses of infrared light
    March 23, 2015
    By Hilary Lebow
    1
    The NIROSETI instrument saw first light on the Nickel 1-meter Telescope at Lick Observatory on March 15, 2015. (Photo by Laurie Hatch) UCSC Lick Nickel telescope

    Astronomers are expanding the search for extraterrestrial intelligence into a new realm with detectors tuned to infrared light at UC’s Lick Observatory. A new instrument, called NIROSETI, will soon scour the sky for messages from other worlds.

    “Infrared light would be an excellent means of interstellar communication,” said Shelley Wright, an assistant professor of physics at UC San Diego who led the development of the new instrument while at the University of Toronto’s Dunlap Institute for Astronomy & Astrophysics.

    Wright worked on an earlier SETI project at Lick Observatory as a UC Santa Cruz undergraduate, when she built an optical instrument designed by UC Berkeley researchers. The infrared project takes advantage of new technology not available for that first optical search.

    Infrared light would be a good way for extraterrestrials to get our attention here on Earth, since pulses from a powerful infrared laser could outshine a star, if only for a billionth of a second. Interstellar gas and dust is almost transparent to near infrared, so these signals can be seen from great distances. It also takes less energy to send information using infrared signals than with visible light.

    5
    UCSC alumna Shelley Wright, now an assistant professor of physics at UC San Diego, discusses the dichroic filter of the NIROSETI instrument. (Photo by Laurie Hatch)

    Frank Drake, professor emeritus of astronomy and astrophysics at UC Santa Cruz and director emeritus of the SETI Institute, said there are several additional advantages to a search in the infrared realm.

    “The signals are so strong that we only need a small telescope to receive them. Smaller telescopes can offer more observational time, and that is good because we need to search many stars for a chance of success,” said Drake.

    The only downside is that extraterrestrials would need to be transmitting their signals in our direction, Drake said, though he sees this as a positive side to that limitation. “If we get a signal from someone who’s aiming for us, it could mean there’s altruism in the universe. I like that idea. If they want to be friendly, that’s who we will find.”

    Scientists have searched the skies for radio signals for more than 50 years and expanded their search into the optical realm more than a decade ago. The idea of searching in the infrared is not a new one, but instruments capable of capturing pulses of infrared light only recently became available.

    “We had to wait,” Wright said. “I spent eight years waiting and watching as new technology emerged.”

    Now that technology has caught up, the search will extend to stars thousands of light years away, rather than just hundreds. NIROSETI, or Near-Infrared Optical Search for Extraterrestrial Intelligence, could also uncover new information about the physical universe.

    “This is the first time Earthlings have looked at the universe at infrared wavelengths with nanosecond time scales,” said Dan Werthimer, UC Berkeley SETI Project Director. “The instrument could discover new astrophysical phenomena, or perhaps answer the question of whether we are alone.”

    NIROSETI will also gather more information than previous optical detectors by recording levels of light over time so that patterns can be analyzed for potential signs of other civilizations.

    “Searching for intelligent life in the universe is both thrilling and somewhat unorthodox,” said Claire Max, director of UC Observatories and professor of astronomy and astrophysics at UC Santa Cruz. “Lick Observatory has already been the site of several previous SETI searches, so this is a very exciting addition to the current research taking place.”

    NIROSETI will be fully operational by early summer and will scan the skies several times a week on the Nickel 1-meter telescope at Lick Observatory, located on Mt. Hamilton east of San Jose.

    The NIROSETI team also includes Geoffrey Marcy and Andrew Siemion from UC Berkeley; Patrick Dorval, a Dunlap undergraduate, and Elliot Meyer, a Dunlap graduate student; and Richard Treffers of Starman Systems. Funding for the project comes from the generous support of Bill and Susan Bloomfield.

     
  • richardmitnick 3:26 pm on March 19, 2018 Permalink | Reply
    Tags: , , , , , , To Understand the Universe Physicists Are Building Their Own, , WIRED   

    FromUBC via Wired: “To Understand the Universe, Physicists Are Building Their Own” 

    U British Columbia bloc

    University of British Columbia

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    Wired

    03.16.18
    Katia Moskvitch

    1
    Inflation is impossible to prove directly. Which is why some physicists want to mimic it in a lab. PASIEKA/GETTY IMAGES.

    Silke Weinfurtner is trying to build the universe from scratch. In a physics lab at the University of Nottingham—close to the Sherwood forest of legendary English outlaw Robin Hood—she and her colleagues will work with a huge superconducting coil magnet, 1 meter across. Inside, there’s a small pool of liquid, whose gentle ripples stand to mimic the matter fluctuations that gave rise to the structures we observe in the cosmos.

    Weinfurtner isn’t an evil genius hell-bent on creating a world of her own to rule. She just wants to understand the origins of the one we already have.

    The Big Bang is by far the most popular model of our universe’s beginnings, but even its fans disagree about how it happened. The theory depends on the existence of a hypothetical quantum field that stretched the universe ultra-rapidly and uniformly in all directions, expanding it by a huge factor in a fraction of a second: a process dubbed inflation. But that inflation or the field responsible for it—the inflaton—is impossible to prove directly. Which is why Weinfurtner wants to mimic it in a lab.

    If the Big Bang theory is right, the baby universe would have been created with tiny ripples—so-called ‘quantum fluctuations’—which got stretched during inflation and turned into matter and radiation, or light. These fluctuations are thought to have eventually magnified to cosmic size, seeding galaxies, stars, and planets. And it’s these tiny ripples that Weinfurtner wants to model with that massive superconducting magnet. Inside, she’ll put a circular tank, some 6 centimeters in diameter, filled with layered water and butanol (the liquids have different densities, so they don’t mix).

    Then, her group of researchers will kick in the artificial gravity distortions. “The strength of the magnetic field varies with its position,” says Richard Hill, one of the paper’s co-authors. “By moving the pool to different regions of the field, the effective gravitational force can be increased or decreased,” he says, “and can even be turned upside-down.”

    By varying gravity, the team hopes to create ripples—but unlike those on a pond, the distortions will appear between the two liquids. “By carefully adjusting the speed of the ripples we can model an inflating universe,” says another team member, Anastasios Avgoustidis. In cosmic inflation, space rapidly expands while the ripples of matter propagate at a constant speed—and in the experiment, the speed of the ripples rapidly decreases as the liquid’s volume remains constant. “The equations describing the propagation of ripples in these two scenarios are identical,” Avgoustidis says.

    That’s important: If the resulting fluctuations look as if they might trigger structures like those found in today’s universe, then we may have had a glimpse of how inflation worked.

    This isn’t the first time Weinfurtner—or anyone else—has tried to mimic cosmic phenomena on a tiny scale. Around the world, astrophysicists can be found in labs, developing ever more sophisticated set-ups using sound waves that travel just like light waves in strong gravitational fields, or magnets to trigger perturbations in fluids and gases.

    Last June, Weinfurtner used a large water tank with a sink in the middle to mimic another difficult-to-observe phenomenon: the superradiance of a black hole. And it was William Unruh, a physicist at the University of British Columbia in Vancouver (and Weinfurtner’s advisor a decade ago), who pioneered the idea of simulating gravity in a lab in 1981. After all, “we cannot rerun the universe—and cannot live long enough to see the results of the experiment if we could,” says Unruh.

    Analog gravity experiments have gotten more sophisticated since Unruh’s first experiment, which used a fluid simulation of gravity to show that the event horizon of a real black hole does to light what a sonic black hole does to sound. In other words: What we can measure and express in the lab can be used to explore properties of astrophysical black holes. It even works for the famous Hawking radiation, the prediction that black holes radiate heat and at some point will totally evaporate. A few years ago, Jeff Steinhauer of the Technion in Haifa, Israel, discovered the radiation’s sonic analog [Nature Physics].

    Simulations are being used to study other aspects of inflation, too. A few years ago, a team led by Christoph Westbrook of CNRS (The French National Center for Scientific Research) in Paris studied the production of quantum particles by ‘wiggling’ a ring Bose Einstein condensate—a state of matter in which the atoms have been cooled to near absolute zero, making them behave as a single quantum object [PACS]. During inflation, the temperature of the universe dropped drastically, before starting to rise again when the inflation ceased with the process called ‘reheating’—leading to the ordinary Big Bang expansion.

    Another experiment last October, led by physicist Stephen Eckel at the Joint Quantum Institute at the National Institute of Standards and Technology and University of Maryland, also used a Bose Einstein condensate to observe the stretching of sound waves—analogous to the stretching, or redshifting, of light that happens as the universe expands. The team also observed an effect similar to the reheating process.

    Weinfurtner says that her ‘novel’ setup can work without a Bose Einstein condensate. That means that the system will be too hot to observe quantum fluctuations directly, says Unruh. But the authors argue that it will be possible to observe the fluctuations via the thermal noise in their system—an analog of quantum noise.

    Their approach, say the authors, will allow them to mimic a long expansion phase, achieving—using the technical language—‘many e-folds,’ a parameter that measures the duration of inflation. Researchers believe that inflation increased the size of the universe by more than a factor of 10^26—or more than 60 e-folds—in just a fraction of a second. The new experiment, if successful, would simulate inflation for much longer period than previous lab set-ups, or have “many more e-folds than any other, enough to put the results beyond doubt,” says Ian Moss of the University of Newcastle. “You need some time to elapse for the system to forget its initial conditions and settle down to the state governed by inflationary fluctuations,” he says.

    “It is possible that they will uncover new physics that help to inform future cosmological models,” says Eckel. “Or, on the reverse, help to test some aspect of future cosmological models.”

    Not everyone is convinced that simulating our universe’s first moments in the lab will help cosmology, though. Ted Jacobson of the University of Maryland thinks that such experiments are “not so much verifying something we are uncertain about, but rather implementing and observing it in a lab.” Why mimic the universe in the lab? “It’s fun. And it may suggest new phenomena we didn’t think of in cosmology,” he says.

    Avi Loeb, an astrophysicist at Harvard University, is not as optimistic. He says that Weinfurtner’s proposed analogy of creating ripples between two fluids in a tank will not extend to the “fundamental physical nature” of quantum fluctuations—because the experiment simply reproduces the equations physicists already use to describe inflation. If these equations are missing a fundamental ingredient, the experiment will not reveal it. “While analog laboratory experiments could incorporate quantum mechanical effects, they do not involve the interplay of quantum mechanics with gravity in the way that black holes and inflation do,” he says.

    Weinfurtner’s experiment is tailored to reproduce our existing notion of inflation, Loeb adds – but it’s not meant to test it at a fundamental level. “The only way to get a discrepancy between the experiment and our notion of inflation is if we did the math wrong for one of these systems. Otherwise, we will learn nothing new,” he says.

    The real test of inflation would be, Loeb says, the production of the substance that propelled it—the inflaton—in the lab. But this would require reaching energies up to a trillion times larger than those achieved in our most powerful particle accelerator, the Large Hadron Collider—and such a test seems unlikely in the near future.

    “Just mimicking the equations of an analogous system is a metaphor to the real system, not an actual test of its fundamental properties,” says Loeb. It’s like “smelling food instead of eating the actual food,” he adds, only “the latter has the real value.”

    That’s true, but sometimes the smells from a kitchen can tell you a lot about what was served for dinner.

    See the full article here .

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    The University of British Columbia is a global centre for research and teaching, consistently ranked among the 40 best universities in the world. Since 1915, UBC’s West Coast spirit has embraced innovation and challenged the status quo. Its entrepreneurial perspective encourages students, staff and faculty to challenge convention, lead discovery and explore new ways of learning. At UBC, bold thinking is given a place to develop into ideas that can change the world.

     
  • richardmitnick 1:26 pm on January 1, 2018 Permalink | Reply
    Tags: , , WIRED   

    From WIRED: “The Sunny Optimism of Clean Energy Shines Through Tech’s Gloom” 

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    WIRED

    01.01.18
    Clive Thompson

    1
    ZOHAR LAZAR

    The mood around tech is dark these days. Social networks are a cesspool of harassment and lies. On-demand firms are producing a bleak economy of gig labor. AI learns to be racist. Is there anyplace where the tech news is radiant with old-fashioned optimism? Where good cheer abounds?

    Why, yes, there is: clean energy. It is, in effect, the new Silicon Valley—filled with giddy, breathtaking ingenuity and flat-out good news.

    This might seem surprising given the climate-change denialism in Washington. But consider, first, residential solar energy. The price of panels has plummeted in the past decade and is projected to drop another 30 percent by 2022. Why? Clever engineering breakthroughs, like the use of diamond wire to slice silicon wafers into ever-skinnier slabs, producing higher yields with less raw material.

    Manufacturing costs are down. According to US government projections, the fastest-growing occupation of the next 10 years will be solar voltaic installer. And you know who switched to solar power last year, because it was so cheap? The Kentucky Coal Museum.

    Tech may have served up Nazis in social media streams, but, hey, it’s also creating microgrids—a locavore equivalent for the solar set. One of these efforts is Brooklyn-based LO3 Energy, a company that makes a paperback-sized device and software that lets owners of solar-equipped homes sell energy to their neighbors—verifying the transactions using the blockchain, to boot. LO3 is testing its system in 60 homes on its Brooklyn grid and hundreds more in other areas.

    “Buy energy and you’re buying from your community,” LO3 founder Lawrence Or­sini tells me. His chipsets can also connect to smart appliances, so you could save money by letting his system cycle down your devices when the network is low on power. The company uses internet logic—smart devices that talk to each other over a dumb network—to optimize power consumption on the fly, making local clean energy ever more viable.

    But wait, doesn’t blockchain number-crunching use so much electricity it generates wasteful heat? It does. So Orsini invented DareHenry, a rack crammed with six GPUs; while it processes math, phase-­changing goo absorbs the outbound heat and uses it to warm a house. Blockchain cogeneration, people! DareHenry is 4 feet of gorgeous, Victorian­esque steampunk aluminum—so lovely you’d want one to show off to guests.

    Solar and blockchain are only the tip of clean tech. Within a few years, we’ll likely see the first home fuel-cell systems, which convert natural gas to electricity. Such systems are “about 80 percent efficient,” marvels Garry Golden, a futurist who has studied clean energy. (He’s also on LO3’s grid, with the rest of his block.)

    The point is, clean energy has a utopian spirit that reminds me of the early days of personal computers. The pioneers of the 1970s were crazy hackers, hell-bent on making machines cheap enough for the masses. Everyone thought they were nuts, or small potatoes—yet they revolutionized communication. When I look at Orsini’s ­blockchain-based energy-trading routers, I see the Altair. And there are oodles more inventors like him.

    Mind you, early Silicon Valley had something crucial that clean energy now does not: massive federal government support. The military bought tons of microchips, helping to scale up computing. Trump’s band of climate deniers aren’t likely to be buyers of first resort for clean energy, but states can do a lot. California already has, for instance, by creating quotas for renewables. So even if you can’t afford this stuff yourself, you should pressure state and local officials to ramp up their solar energy use. It’ll give us all a boost of much-needed cheer.

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  • richardmitnick 1:19 pm on December 2, 2017 Permalink | Reply
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    From WIRED: “A Hidden Supercluster Could Solve the Mystery of the Milky Way” 

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    WIRED

    12.02.17
    Liz Kruesi

    1
    The Vela supercluster in its wider surroundings: The image displays the smoothed redshift distribution of galaxies in and around the Vela supercluster (larger ellipse; VSC). The centre of the image, so-called the Zone of Avoidance, is covered by the Milky Way (with its stellar fields and dust layers shown in grey scale), which obscures all structures behind it. Colour indicates the distance ranges of all galaxies within 500 – 1000 million light years (yellow is close to the peak of the Vela supercluster, green is nearer and orange further away). The ellipse marks the approximate extent of the Vela Supercluster, crossing the Galactic Plane. The VSC structure was revealed thanks to the new low latitude spectroscopic redshifts. Given its prominence on either side of the plane of the Milky Way it would be highly unlikely for these cosmic large-scale structures not to be connected across the Galactic Plane. The structure may be similar in aggregate mass to the Shapley Concentration (SC, smaller ellipse), although much more extended. The so-called “Great Attractor” (GA), located much closer to the Milky Way, is an example of a large web structure that crosses the Galactic Plane, although much smaller in extent than VSC. The central, dust-shrouded part of the VSC remains unmapped in the current Vela survey. Also visible are the Milky Way’s two satellite galaxies, LMC and SMC, located south of the Galactic plane. Image credit: Thomas Jarrett (UCT)

    2
    An illustration of the Vela Supercluster peeking out from behind the Milky Way’s Zone of Avoidance. Mike Zeng/Quanta Magazine

    Glance at the night sky from a clear vantage point, and the thick band of the Milky Way will slash across the sky. But the stars and dust that paint our galaxy’s disk are an unwelcome sight to astronomers who study all the galaxies that lie beyond our own. It’s like a thick stripe of fog across a windshield, a blur that renders our knowledge of the greater universe incomplete. Astronomers call it the Zone of Avoidance.

    3
    Zone of Avoidance. NASA/Spitzer

    Renée Kraan-Korteweg has spent her career trying to uncover what lies beyond the zone. She first caught a whiff of something spectacular in the background when, in the 1980s, she found hints of a potential cluster of objects on old photographic survey plates. Over the next few decades, the hints of a large-scale structure kept coming.

    Late last year, Kraan-Korteweg and colleagues announced that they had discovered an enormous cosmic structure: a “supercluster” of thousands upon thousands of galaxies. The collection spans 300 million light years, stretching both above and below the galactic plane like an ogre hiding behind a lamppost. The astronomers call it the Vela Supercluster, for its approximate position around the constellation Vela.

    Milky Way Movers

    The Milky Way, just like every galaxy in the cosmos, moves. While everything in the universe is constantly moving because the universe itself is expanding, since the 1970s astronomers have known of an additional motion, called peculiar velocity. This is a different sort of flow that we seem to be caught in. The Local Group of galaxies—a collection that includes the Milky Way, Andromeda and a few dozen smaller galactic companions—moves at about 600 kilometers per second with respect to the leftover radiation from the Big Bang.

    Local Group. Andrew Z. Colvin 3 March 2011

    Andromeda Galaxy Adam Evans

    Small Magellanic Cloud. NASA/ESA Hubble and ESO/Digitized Sky Survey 2

    Large Magellanic Cloud. Adrian Pingstone December 2003

    Over the past few decades, astronomers have tallied up all the things that could be pulling and pushing on the Local Group — nearby galaxy clusters, superclusters, walls of clusters and cosmic voids that exert a non-negligible gravitational pull on our own neighborhood.

    Laniakea supercluster. From Nature The Laniakea supercluster of galaxies R. Brent Tully, Hélène Courtois, Yehuda Hoffman & Daniel Pomarède at http://www.nature.com/nature/journal/v513/n7516/full/nature13674.html. Milky Way is the red dot.

    The biggest tugboat is the Shapley Supercluster, a behemoth of 50 million billion solar masses that resides about 500 million light years away from Earth (and not too far away in the sky from the Vela Supercluster). It accounts for between a quarter and half of the Local Group’s peculiar velocity.

    3
    Shapley Supercluster. http://www.atlasoftheuniverse.com/superc/shapley.html

    The remaining motion can’t be accounted for by structures astronomers have already found. So astronomers keep looking farther out into the universe, tallying increasingly distant objects that contribute to the net gravitational pull on the Milky Way. Gravitational pull decreases with increasing distance, but the effect is partly offset by the increasing size of these structures. “As the maps have gone outward,” said Mike Hudson, a cosmologist at the University of Waterloo in Canada, “people continue to identify bigger and bigger things at the edge of the survey. We’re looking out farther, but there’s always a bigger mountain just out of sight.” So far astronomers have only been able to account for about 450 to 500 kilometers per second of the Local Group’s motion.

    Astronomers still haven’t fully scoured the Zone of Avoidance to those same depths, however. And the Vela Supercluster discovery shows that something big can be out there, just out of reach.

    In February 2014, Kraan-Korteweg and Michelle Cluver, an astronomer at the University of Western Cape in South Africa, set out to map the Vela Supercluster over a six-night observing run at the Anglo-Australian Telescope in Australia. Kraan-Korteweg, of the University of Cape Town, knew where the gas and dust in the Zone of Avoidance was thickest; she targeted individual spots where they had the best chance of seeing through the zone. The goal was to create a “skeleton,” as she calls it, of the structure. Cluver, who had prior experience with the instrument, would read off the distances to individual galaxies.

    That project allowed them to conclude that the Vela Supercluster is real, and that it extends 20 by 25 degrees across the sky. But they still don’t understand what’s going on in the core of the supercluster. “We see walls crossing the Zone of Avoidance, but where they cross, we don’t have data at the moment because of the dust,” Kraan-Korteweg said. How are those walls interacting? Have they started to merge? Is there a denser core, hidden by the Milky Way’s glow?

    And most important, what is the Vela’s Supercluster’s mass? After all, it is mass that governs the pull of gravity, the buildup of structure.

    How to See Through the Haze

    While the Zone’s dust and stars block out light in optical and infrared wavelengths, radio waves can pierce through the region. With that in mind, Kraan-Korteweg has a plan to use a type of cosmic radio beacon to map out everything behind the thickest parts of the Zone of Avoidance.

    The plan hinges on hydrogen, the simplest and most abundant gas in the universe. Atomic hydrogen is made of a single proton and an electron. Both the proton and the electron have a quantum property called spin, which can be thought of as a little arrow attached to each particle. In hydrogen, these spins can line up parallel to each other, with both pointing in the same direction, or antiparallel, pointing in opposite directions. Occasionally a spin will flip—a parallel atom will switch to antiparallel. When this happens, the atom will release a photon of light with a particular wavelength.

    The likelihood of one hydrogen atom’s emitting this radio wave is low, but gather a lot of neutral hydrogen gas together, and the chance of detecting it increases. Luckily for Kraan-Korteweg and her colleagues, many of Vela’s member galaxies have a lot of this gas.

    During that 2014 observing session, she and Cluver saw indications that many of their identified galaxies host young stars. “And if you have young stars, it means they recently formed, it means there’s gas,” Kraan-Korteweg said, because gas is the raw material that makes stars.

    The Milky Way has some of this hydrogen, too—another foreground haze to interfere with observations. But the expansion of the universe can be used to identify hydrogen coming from the Vela structure. As the universe expands, it pulls away galaxies that lie outside our Local Group and shifts the radio light toward the red end of the spectrum. “Those emission lines separate, so you can pick them out,” said Thomas Jarrett, an astronomer at the University of Cape Town and part of the Vela Supercluster discovery team.

    While Kraan-Korteweg’s work over her career has dug up some 5,000 galaxies in the Vela Supercluster, she is confident that a sensitive enough radio survey of this neutral hydrogen gas will triple that number and reveal structures that lie behind the densest part of the Milky Way’s disk.

    That’s where the MeerKAT radio telescope enters the picture. Located near the small desert town of Carnarvon, South Africa, the instrument will be more sensitive than any radio telescope on Earth. Its 64th and final antenna dish was installed in October, although some dishes still need to be linked together and tested. A half array of 32 dishes should be operating by the end of this year, with the full array following early next year.

    SKA Meerkat telescope, 90 km outside the small Northern Cape town of Carnarvon, SA

    Kraan-Korteweg has been pushing over the past year for observing time in this half-array stage, but if she isn’t awarded her requested 200 hours, she’s hoping for 50 hours on the full array. Both options provide the same sensitivity, which she and her colleagues need to detect the radio signals of neutral hydrogen in thousands of individual galaxies hundreds of light years away. Armed with that data, they’ll be able to map what the full structure actually looks like.

    Cosmic Basins

    Hélène Courtois, an astronomer at the University of Lyon, is taking a different approach to mapping Vela. She makes maps of the universe that she compares to watersheds, or basins. In certain areas of the sky, galaxies migrate toward a common point, just as all the rain in a watershed flows into a single lake or stream. She and her colleagues look for the boundaries, the tipping points of where matter flows toward one basin or another.

    A few years ago, Courtois and colleagues used this method to attempt to define our local large-scale structure, which they call Laniakea. The emphasis on defining is important, Courtois explains, because while we have definitions of galaxies and galaxy clusters, there’s no commonly agreed-upon definition for larger-scale structures in the universe such as superclusters and walls.

    Part of the problem is that there just aren’t enough superclusters to arrive at a statistically rigorous definition. We can list the ones we know about, but as aggregate structures filled with thousands of galaxies, superclusters show an unknown amount of variation.

    Now Courtois and colleagues are turning their attention farther out. “Vela is the most intriguing,” Courtois said. “I want to try to measure the basin of attraction, the boundary, the frontier of Vela.” She is using her own data to find the flows that move toward Vela, and from that she can infer how much mass is pulling on those flows. By comparing those flow lines to Kraan-Korteweg’s map showing where the galaxies physically cluster together, they can try to address how dense of a supercluster Vela is and how far it extends. “The two methods are totally complementary,” Courtois added.

    The two astronomers are now collaborating on a map of Vela. When it’s complete, the astronomers hope that they can use it to nail down Vela’s mass, and thus the puzzle of the remaining piece of the Local Group’s motion—“that discrepancy that has been haunting us for 25 years,” Kraan-Korteweg said. And even if the supercluster isn’t responsible for that remaining motion, collecting signals through the Zone of Avoidance from whatever is back there will help resolve our place in the universe.

    See the full article here .

    Please help promote STEM in your local schools.

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  • richardmitnick 12:21 pm on September 11, 2017 Permalink | Reply
    Tags: , , WIRED   

    From WIRED: “The Astonishing Engineering Behind America’s Latest, Greatest Supercomputer” 

    Wired logo

    WIRED

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    HOTLITTLEPOTATO

    If you want to do big, serious science, you’ll need a serious machine. You know, like a giant water-cooled computer that’s 200,000 times more powerful than a top-of-the-line laptop and that sucks up enough energy to power 12,000 homes.

    You’ll need Summit, a supercomputer nearing completion at the Oak Ridge National Laboratory in Tennessee.

    ORNL IBM Summit Supercomputer

    When it opens for business next year, it’ll be the United States’ most powerful supercomputer and perhaps the most powerful in the world. Because as science gets bigger, so too must its machines, requiring ever more awesome engineering, both for the computer itself and the building that has to house it without melting. Modeling the astounding number of variables that affect climate change, for instance, is no task for desktop computers in labs. Some goes for genomics work and drug discovery and materials science. If it’s wildly complex, it’ll soon course through Summit’s circuits.

    Summit will be five to 10 times more powerful than its predecessor, Oak Ridge’s Titan supercomputer, which will continue running its science for about a year after Summit comes online.

    ORNL Cray Titan XK7 Supercomputer

    (Not that there’s anything wrong with Titan. It’s just that at 5 years old, the machine is getting on in years by supercomputer standards.) But it’ll be pieced together in much the same way: cabinet after cabinet of so-called nodes. While each node for Titan, all 18,688 of them, consists of one CPU and one GPU, with Summit it’ll be two CPUs working with six GPUs.

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    Diagram showing how chilled water is delivered to the building.
    Heery International

    Think of the GPU as a turbocharger for the CPU in this relationship. While not all supercomputers use this setup, known as a heterogeneous architecture, those that do get a boost―each of the 4,600 nodes in Summit can manage 40 teraflops. So at peak performance, Summit will hit 200 petaflops, a petaflop being one million billion operations a second. “So we envision research teams using all of those GPUs on every single node when they run, that’s sort of our mission as a facility,” says Stephen McNally, operations manager.

    Performing all those operations sucks up a lot of power and generates a ton of heat. That poses a daunting challenge for Heery, the company charged with preventing Summit from overheating and powering the building that houses it. Heery’s piping in 20 megawatts of electricity (the supercomputer itself will run on 15 megawatts), enough juice to power a decent-sized city. “12,000 Southern homes with their air conditioners cranking would be roughly 20 megawatts of power,” says George Wellborn, senior associate at Heery. Luckily, Oak Ridge is hooked up to the Tennessee Valley Authority, which in Tennessee alone has a generating capacity of nearly 20,000 megawatts from 19 hydroelectric dams, two nuclear power plants, and too many other sources to get into here.

    Another engineering pickle: Each of the supercomputer’s 4,600 nodes needs to be cooled individually. Summit will use water. (Titan uses a refrigerant. You could also cool your electronics in a bath of mineral oil, if you were so inclined.) “Every one of those nodes is using a cold plate technology, where we’re putting water through a cold plate that’s directly on top,” says Jim Rogers, director for computing and facilities. “So 70 percent of the heat that’s generated by this thing can be absorbed by that cold plate.”

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    Overhead view of Summit. Heery International

    Curiously, this isn’t super-chilled water―it’s a comfortable 70 degrees Fahrenheit. Why? Because if you drop the temperature too much, you’ll form dew, which is a great way to ruin a supercomputer. “You have to have higher flow rates to carry the heat away,” Rogers says (we’re talking a max flow of nearly 8,000 gallons per minute), “but that tradeoff is good in terms of energy efficiency and operating cost.”

    Summit still has to … summit some final steps before it can start crunching heavy-duty science. Its cabinets should all be installed by late October, then it will undergo a year of testing and debugging. But soon enough, one of the most impressive devices humankind has ever assembled will go node to node with the best supercomputers in the world.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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