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  • richardmitnick 12:49 pm on July 21, 2019 Permalink | Reply
    Tags: "A golden era of exploration: ATLAS highlights from EPS-HEP 2019", , , , , , ,   

    From CERN ATLAS: “A golden era of exploration: ATLAS highlights from EPS-HEP 2019” 

    CERN/ATLAS detector

    CERN ATLAS Higgs Event

    CERN ATLAS another view Image Claudia Marcelloni ATLAS CERN


    CERN ATLAS New II Credit CERN SCIENCE PHOTO LIBRARY


    From CERN ATLAS

    20th July 2019
    Katarina Anthony

    1
    Event display of a Higgs boson candidate decaying in the four-lepton channel. (Image: ATLAS Collaboration/CERN)

    Eight years of operation. Over 10,000 trillion high-energy proton collisions. One critical new particle discovery. Countless new insights into our universe. The Large Hadron Collider (LHC) has been breaking records since data-taking began in 2010 – and yet, for ATLAS and its fellow LHC experiments, a golden era of exploration is only just beginning.

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    Figure 1: New ATLAS measurement of the Higgs boson decaying in the four-lepton channel, using the full LHC Run-2 dataset. The distribution of the invariant mass of the four leptons (m4l) is shown. The Higgs boson corresponds to the excess of events (blue) over the non-resonant ZZ* background (red) at 125 GeV. (Image: ATLAS Collaboration/CERN)

    This week, the ATLAS Collaboration presented 25 new results at the European Physical Society’s High-Energy Physics conference (EPS-HEP) in Ghent, Belgium. The new analyses examine the largest-ever proton–proton collision dataset from the LHC, recorded during Run 2 of the accelerator (2015–2018) at the 13 TeV energy frontier.

    The new data have been fertile ground for ATLAS. New precision measurements of the Higgs boson, observations of key electroweak processes and high-precision tests of the Standard Model are among the highlights described below; find the full list of ATLAS public results using the full Run-2 dataset here.

    Studying the Higgs discovery channels

    Just over seven years ago, the Higgs boson was an elusive particle, out of reach from physicists for nearly five decades. Today, not only is the Higgs boson frequently observed, it is studied with such precision as to become a powerful tool for exploration.

    Key to these accomplishments are the so-called “Higgs discovery channels”: H→γγ, where the Higgs boson decays into two photons, and H→ZZ*→4l, where it decays via two Z bosons into four leptons. Though rare, these decays are easily identified in the ATLAS detector, making them essential to both the particle’s discovery and study.

    ATLAS presented new explorations of the Higgs boson in these channels (Figures 1 and 2), yielding greater insight into its behaviour. The new results benefit from the large full Run-2 dataset, as well as a number of new improvements to the analysis techniques. For example, ATLAS physicists now utilise Deep-Learning Neural Networks to assign the Higgs-boson events to specific production modes.

    All four Higgs-boson production modes can now be clearly identified in a single decay channel. ATLAS’ studies of the Higgs boson have advanced so quickly, in fact, that rare processes – such as its production in association with a top-quark pair, observed only just last year – can now been seen in just a single decay channel. The new sensitivity allowed physicists to measure kinematic properties of the Higgs boson with unprecedented precision (Figure 3). These are sensitive to new physics processes, making their exploration of particular interest to the collaboration.

    All four Higgs-boson production modes can now be clearly identified in a single decay channel. ATLAS’ studies of the Higgs boson have advanced so quickly, in fact, that rare processes – such as its production in association with a top-quark pair, observed only just last year – can now been seen in just a single decay channel. The new sensitivity allowed physicists to measure kinematic properties of the Higgs boson with unprecedented precision (Figure 3). These are sensitive to new physics processes, making their exploration of particular interest to the collaboration.

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    Figure 2: Distribution of the invariant mass of the two photons in the ATLAS measurement of H→γγ using the full Run-2 dataset. The Higgs boson corresponds to the excess of events observed at 125 GeV with respect to the non-resonant background (dashed line). (Image: ATLAS Collaboration/CERN)

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    Figure 3: Differential cross section for the transverse momentum (pT,H) of the Higgs boson from the two individual channels (H→ZZ*→4ℓ, H→γγ) and their combination. (Image: ATLAS Collaboration/CERN)

    Searching unseen properties of the Higgs boson

    Having accomplished the observation of Higgs boson interactions with third-generation quarks and leptons, ATLAS physicists are turning their focus to the lighter, second-generation of fermions: muons, charm quarks and strange quarks. While their interactions with the Higgs boson are described by the Standard Model, they have – so far – remained relegated to theory. Results from the ATLAS Collaboration are backing up these theories with real data.

    At EPS-HEP, ATLAS presented a new search for the Higgs boson decaying into muon pairs. This already-rare process is made all the more difficult to detect by background Standard Model processes, which produce muon pairs in abundance.

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    Figure 4: ATLAS search for the Higgs boson decaying to two muons. The plot shows the weighted muon pair invariant mass spectrum (muu) summed over all categories. (Image: ATLAS Collaboration/CERN)

    The new result utilised novel machine learning techniques to provide ATLAS’ most sensitive result yet, with a moderate excess of 1.5 standard deviations expected for the predicted signal. In agreement with this prediction, only a small excess of 0.8 standard deviations is present around the Higgs-boson mass in the data (Figure 4).

    “This result shows that we are now close to the sensitivity required to test the Standard Model’s predictions for this very rare decay of the Higgs boson,” said ATLAS spokesperson Karl Jakobs from the University of Freiburg, Germany. “However, a definitive statement on the second generation will require the larger datasets that will be provided by the LHC in Run 3 and by the High-Luminosity LHC.”

    ATLAS’ growing sensitivity was also clearly on display in the collaboration’s new “di-Higgs” search, where two Higgs bosons are formed via the fusion of two vector bosons. Though one of the rarest Standard Model processes explored by ATLAS, its study gives unique insight into the previously-untested relationship between vector boson and Higgs-boson pairs. A small variation of this coupling relative to the Standard Model value would result in a dramatic rise in the measured cross section. The new search, despite being negative, successfully sets the first constraints on this relationship.

    Entering the Higgs sector

    The Higgs mechanism, giving mass to all elementary particles, is directly connected with profound questions about our universe, including the stability and energy of the vacuum, the “naturalness” of a world described by the Standard Model, and more. As such, the exploration of the Higgs sector is not limited to direct measurements of the Higgs boson – it instead requires a broad experimental programme that will extend over decades.

    A perfect example of this came in ATLAS’ new observation of the electroweak production of two jets in association with a pair of Z bosons. The Z and W bosons are the force carriers of weak interactions and, as they both have a spin of 1, are known as “vector bosons”. The Higgs boson is a vital mediator in “vector-boson scattering”, an electroweak process that contributes to the pair production of vector bosons (WW, WZ and ZZ) with jets. Measurements of these production processes are key for the study of electroweak symmetry breaking via the Higgs mechanism.

    The new ATLAS result – with a statistical significance of 5.5 standard deviations (Figure 5) – completes the experiment’s observation of vector-boson scattering in these critical processes, and sparks new ways to test the Standard Model.

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    Figure 5: Observed and predicted distributions (BDT) in the signal regions of Z-boson pairs decaying to four leptons. The electroweak production of the Z-boson pair is shown in red; the error bars on the data points (black) show the statistical uncertainty on data. (Image: ATLAS Collaboration/CERN)

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    Figure 6: Summary of the mass limits on supersymmetry models set by the ATLAS searches for Supersymmetry. Results are quoted for the nominal cross section in both a region of near-maximal mass reach and a demonstrative alternative scenario, in order to display the range in model space of search sensitivity. (Image: ATLAS Collaboration/CERN)

    Probing new physics

    As the community enters the tenth year of supersymmetry searches at the LHC, the ATLAS Collaboration continues to take a broad approach to the hunt. ATLAS is committed to providing results that are theory-independent as well as signature-based searches, in addition to the highly-targeted, model-dependent ones.

    Along with new, updated limits on various supersymmetry searches using the full Run-2 dataset (Figure 6), ATLAS once again highlighted new searches (first presented at the LHCP2019 conference) for superpartners produced through the electroweak interaction. Generated at extremely low rates at the LHC and decaying into Standard Model particles that are themselves difficult to reconstruct, such supersymmetry searches can only be described by the iconic quote: “not because it is easy, but because it is hard”.

    Overall, the results place strong constraints on important supersymmetric scenarios, which will inform theory developments and future ATLAS searches. Further, they provide examples of how advanced reconstruction techniques can help improve the ATLAS’ sensitivity of new physics searches.

    Asymmetric top-quark production

    The Standard Model continued to show its strength in ATLAS’ new precision measurement of charge asymmetry in top-quark pairs (Figure 7). This intriguing imbalance – where top and antitop quarks are not produced equally at all angles with respect to the proton beam direction – is among the most subtle, difficult and yet vital properties to measure in the study of top quarks.

    The effect of this asymmetry is predicted to be extremely small, however new physics processes interfering with the known production modes can lead to larger (or even smaller) values. ATLAS found evidence of this imbalance, with a significance of four standard deviations, with a value compatible with the Standard Model. The result marks an important milestone for the field, following decades of measurements which began at the Tevatron proton–antiproton collider, the predecessor of the LHC in the USA.

    FNAL/Tevatron


    FNAL/Tevatron map

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    Figure 7: Measured values of the charge asymmetry (Ac) as a function of the invariant mass of the top quark pair system (mtt) in data. (Image: ATLAS Collaboration/CERN)

    Following the data

    As EPS-HEP 2019 drew to a close, it was clear that exploration of the high-energy frontier remains far from complete. With the LHC – and its upcoming HL-­LHC upgrade – set to continue apace, the future of high-energy physics will be guided by the results of ATLAS and its fellow experiments at the energy frontier.

    “Our community is living through data-driven times,” said ATLAS Deputy Spokesperson Andreas Hoecker from CERN. “Experimental results must guide the high-energy physics community to the next stage of exploration. This requires a broad and diverse particle physics research programme. The ATLAS Collaboration is up to taking this challenge!”

    See the full article here .


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  • richardmitnick 11:29 am on July 21, 2019 Permalink | Reply
    Tags: , , , , , , , Is anyone out there?, , , Shelley Wright of UCSD and Niroseti at UCSC Lick Observatory's Nickel Telescope,   

    From WIRED: “An Alien-Hunting Tech Mogul May Help Solve a Space Mystery” 

    Wired logo

    From WIRED

    07.21.19
    Katia Moskvitch

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    Yuri Milner. Billy H.C. Kwok/Getty Images

    In spring 2007, David Narkevic, a physics student at West Virginia University, was sifting through reams of data churned out by the Parkes telescope—a dish in Australia that had been tracking pulsars, the collapsed, rapidly spinning cores of once massive stars.

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

    His professor, astrophysicist Duncan Lorimer, had asked him to search for a recently discovered type of ultra-rapid pulsar dubbed RRAT. But buried among the mountain of data, Narkevic found an odd signal that seemed to come from the direction of our neighboring galaxy, the Small Magellanic Cloud.

    smc

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

    The signal was unlike anything Lorimer had encountered before. Although it flashed only briefly, for just five milliseconds, it was 10 billion times brighter than a typical pulsar in the Milky Way galaxy. It was emitting in a millisecond as much energy as the sun emits in a month.

    What Narkevic and Lorimer found was the first of many bizarre, ultra-powerful flashes detected by our telescopes. For years the flashes first seemed either improbable or at least vanishingly rare. But now researchers have observed more than 80 of these Fast Radio Bursts, or FRBs. While astronomers once thought that what would be later dubbed the “Lorimer Burst” was a one-off, they now agree that there’s probably one FRB happening somewhere in the universe nearly every second.

    And the reason for this sudden glut of discoveries? Aliens. Well, not aliens per se, but the search for them. Among the scores of astronomers and researchers working tirelessly to uncover these enigmatic signals is an eccentric Russian billionaire who, in his relentless hunt for extraterrestrial life, has ended up partly bankrolling one of the most complex and far-reaching scans of our universe ever attempted.

    Ever since Narkevic spotted the first burst, scientists have been wondering what could produce these mesmerizing flashes in deep space. The list of possible sources is long, ranging from the theoretical to the simply unfathomable: colliding black holes, white holes, merging neutron stars, exploding stars, dark matter, rapidly spinning magnetars, and malfunctioning microwaves have all been proposed as possible sources.

    While some theories can now be rejected, many live on. Finally though, after more than a decade of searching, a new generation of telescopes is coming online that could help researchers to understand the mechanism that is producing these ultra-powerful bursts. In two recent back-to-back papers, one published last week and one today, two different arrays of radio antennas—the Australian Square Kilometer Array Pathfinder (ASKAP) and Caltech’s Deep Synoptic Array 10 at the Owens Valley Radio Observatory (OVRO) in the US—have for the first time ever been able to precisely locate two different examples of these mysterious one-off FRBs.

    Australian Square Kilometre Array Pathfinder (ASKAP) is a radio telescope array located at Murchison Radio-astronomy Observatory (MRO) in the Australian Mid West. ASKAP consists of 36 identical parabolic antennas, each 12 metres in diameter, working together as a single instrument with a total collecting area of approximately 4,000 square metres.

    Caltech’s Deep Synoptic Array 10 dish array at Owens Valley Radio Observatory, near Big Pine, California USA, Altitude 1,222 m (4,009 ft

    Physicists are now expecting that two other new telescopes—Chime (the Canadian Hydrogen Intensity Mapping Experiment) in Canada and MeerKAT in South Africa—will finally tell us what produces these powerful radio bursts.

    CHIME Canadian Hydrogen Intensity Mapping Experiment -A partnership between the University of British Columbia, the University of Toronto, McGill University, Yale and the National Research Council in British Columbia, at the Dominion Radio Astrophysical Observatory in Penticton, British Columbia, CA Altitude 545 m (1,788 ft)

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

    But Narkevic’s and Lorimer’s discovery nearly got binned. For a few months after they first spotted the unusually bright burst, it looked like the findings wouldn’t make it any further than Lorimer’s office walls, just beyond the banks of the Monongahela River that slices through the city of Morgantown in West Virginia.

    Soon after detecting the burst, Lorimer asked his former graduate adviser Matthew Bailes, an astronomer at Swinburne University in Melbourne, to help him plot the signal—which to astronomers is now a famous and extremely bright energy peak, rising well above the power of any known pulsar. The burst seemed to come from much, much further away than where the Parkes telescope would usually find pulsars; in this case, probably from another galaxy, potentially billions of light-years away.

    “It just looked beautiful. I was like, ‘Whoa, that’s amazing.’ We nearly fell off our chairs,” recalls Bailes. “I had trouble sleeping that night because I thought if this thing is really that far away and that insanely bright, it’s an amazing discovery. But it better be right.”

    Within weeks, Lorimer and Bailes crafted a paper and sent it to Nature—and swiftly received a rejection. In a reply, a Nature editor raised concerns that there had been only one event, which appeared way brighter than seemed possible. Bailes was disappointed, but he had been in a worse situation before. Sixteen years earlier, he and fellow astronomer Andrew Lyne had submitted a paper claiming to have spotted the first ever planet orbiting another star—and not just any star but a pulsar. The scientific discovery turned out to be a fluke of their telescope. Months later, Lyne had to stand up in front of a large audience at an American Astronomical Society conference and announce their mistake. “It’s science. Anything can happen,” says Bailes. This time around, Bailes and Lorimer were certain that they had it right and decided to send their FRB paper to another journal, Science.

    After it was published, the paper immediately stirred interest; some scientists even wondered whether the mysterious flash was an alien communication. This wasn’t the first time that astronomers had reached for aliens as the answer for a seemingly inexplicable signal from space; in 1967, when researchers detected what turned out to be the first pulsar, they also wondered whether it could be a sign of intelligent life.

    Just like Narkevic decades later, Cambridge graduate student Jocelyn Bell had stumbled across a startling signal in the reams of data gathered by a radio array in rural Cambridgeshire.

    Women in STEM – Dame Susan Jocelyn Bell Burnell

    Dame Susan Jocelyn Bell Burnell, discovered pulsars with radio astronomy. Jocelyn Bell at the Mullard Radio Astronomy Observatory, Cambridge University, taken for the Daily Herald newspaper in 1968. Denied the Nobel.

    Dame Susan Jocelyn Bell Burnell at work on first plusar chart 1967 pictured working at the Four Acre Array in 1967. Image courtesy of Mullard Radio Astronomy Observatory.

    Dame Susan Jocelyn Bell Burnell 2009

    Dame Susan Jocelyn Bell Burnell (1943 – ), still working from http://www. famousirishscientists.weebly.com

    Not much of the array is left today; in the fields near the university where it once stood, there’s an overgrown hedge, hiding a collection of wonky, sad-looking wooden poles that were once covered in a web of copper wire designed to detect radio waves from faraway sources. The wire has long been stolen and sold on to scrap metal dealers.

    “We did seriously consider the possibility of aliens,” Bell says, now an emeritus professor at Oxford University. Tellingly, the first pulsar was half-jokingly dubbed LGM-1 —for little green men. With only half a year left until the defense of her PhD thesis, she was less than thrilled that “some silly lot of little green men” were using her telescope and her frequency to signal to planet Earth. Why would aliens “be using a daft technique signaling to what was probably still a rather inconspicuous planet?” she once wrote in an article for Cosmic Search Magazine.

    Just a few weeks later, however, Bell spotted a second pulsar, and then a third just as she got engaged, in January 1968. Then, as she was defending her thesis and days before her wedding, she discovered a fourth signal in yet another part of the sky. Proof that pulsars had to be a natural phenomenon of an astrophysical origin, not a signal from intelligent life. Each new signal made the prospect even more unlikely that groups of aliens, separated by the vastness of the space, were somehow coordinating their efforts to send a message to an uninteresting hunk of rock on the outskirts of the Milky Way.

    Lorimer wasn’t so lucky. After the first burst, six years would pass without another detection. Many scientists began to lose interest. The microwave explanation persisted for a while, says Lorimer, as skeptics sneered at the notion of finding a burst that was observed only once. It didn’t help that in 2010 Parkes detected 16 similar pulses, which were quickly proven to be indeed caused by the door of a nearby microwave oven that had been opened suddenly during its heating cycle.

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    Yuri Milner on stage with Mark Zuckerberg at a Breakthrough Prize event in 2017. Kimberly White/Getty Images

    When Avi Loeb first read of Lorimer’s unusual discovery, he too wondered if it was nothing more than the result of some errant wiring or miscalibrated computer. The chair of the astronomy department at Harvard happened to be in Melbourne in November 2007, just as Lorimer’s and Bailes’ paper appeared in Science, so he had a chance to discuss the odd burst with Bailes. Loeb thought the radio flash was a compelling enigma—but not much more than that.

    Still, that same year Loeb wrote a theoretical paper arguing that radio telescopes built to detect very specific hydrogen emissions from the early universe would also be able to eavesdrop on radio signals from alien civilizations up to about 10 light-years away. “We have been broadcasting for a century—so another civilization with the same arrays can see us from a distance out to 50 light-years,” was Loeb’s reasoning. He followed up with another paper on the search for artificial lights in the solar system. There, Loeb showed that a city as bright as Tokyo could be detected with the Hubble Space Telescope even if it was located right at the edge of the solar system. In yet another paper he argued how to detect industrial pollution in planetary atmospheres.

    Ever since he was a little boy growing up in Israel, Loeb has been fascinated with life—on Earth and elsewhere in the universe. “Currently, the search for microbial life is part of the mainstream in astronomy—people are looking for the chemical fingerprints of primitive life in the atmosphere of exoplanets,” says Loeb, who first dabbled in philosophy before his degree in physics.

    But the search for intelligent life beyond Earth should also be part of the mainstream, he argues. “There is a taboo, it’s a psychological and sociological problem that people have. It’s because there is the baggage of science fiction and UFO reports, both of which have nothing to do with what actually goes on out there in space,” he adds. He’s frustrated with having to explain—and defend—his point of view. After all, he says, billions have been poured into the search for dark matter over decades with zero results. Should the search for extraterrestrial intelligence, more commonly known as SETI, be regarded as even more fringe than this fruitless search?

    Lorimer didn’t follow Loeb’s SETI papers closely. After six long and frustrating years, his luck turned in 2013, when a group of his colleagues—including Bailes—spotted four other bright radio flashes in Parkes’ data. Lorimer felt vindicated and relieved. More detections followed and the researchers were on a roll: At long last, FRBs had been confirmed as a real thing. After the first event was dubbed “Lorimer’s Burst,” it swiftly made it onto the physics and astronomy curricula of universities around the globe. In physics circles, Lorimer was elevated to the position of a minor celebrity.

    Keeping an eye on events from a distance was Loeb. One evening in February 2014, at a dinner in Boston, he started chatting to a charismatic Russian-Israeli called Yuri Milner, a billionaire technology investor with a background in physics and a well-known name in Silicon Valley. Ever since he could remember, Milner had been fascinated with life beyond Earth, a subject close to Loeb’s heart; the two instantly hit it off.

    Milner came to see Loeb again in May the following year, at Harvard, and asked the academic how long it would take to travel to Alpha Centauri, the star system closest to Earth.

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    Loeb replied he would need half a year to identify the technology that would allow humans to get there in their lifetime. Milner then asked Loeb to lead Breakthrough Starshot, one of five Breakthrough Initiatives the Russian oligarch was about to announce in a few weeks—backed by $100 million of his own money and all designed to support SETI.

    Breakthrough Starshot Initiative

    Breakthrough Starshot

    ESO 3.6m telescope & HARPS at LaSilla, 600 km north of Santiago de Chile at an altitude of 2400 metres.

    SPACEOBS, the San Pedro de Atacama Celestial Explorations Observatory is located at 2450m above sea level, north of the Atacama Desert, in Chile, near to the village of San Pedro de Atacama and close to the border with Bolivia and Argentina

    SNO Sierra Nevada Observatory is a high elevation observatory 2900m above the sea level located in the Sierra Nevada mountain range in Granada Spain and operated maintained and supplied by IAC

    Teide Observatory in Tenerife Spain, home of two 40 cm LCO telescopes

    Observatori Astronòmic del Montsec (OAdM), located in the town of Sant Esteve de la Sarga (Pallars Jussà), 1,570 meters on the sea level

    Bayfordbury Observatory,approximately 6 miles from the main campus of the University of Hertfordshire

    Fast-forward six months, and at the end of December 2015 Loeb got a call asking him to prepare a presentation summarizing his recommended technology for the Alpha Centauri trip. Loeb was visiting Israel and about to head on a weekend trip to a goat farm in the southern part of the country. “The following morning, I was sitting next to the reception of the farm—the only location with internet connectivity—and typing the PowerPoint presentation that contemplated a lightsail technology for Yuri’s project,” says Loeb. He presented it at Milner’s home in Moscow two weeks later, and the Breakthrough Initiatives were announced with fanfare in July 2015.

    The initiatives were an adrenaline shot in the arm of the SETI movement—the largest ever private cash injection into the search for aliens. One of the five projects is Breakthrough Listen, which was championed, among others, by the famous astronomer Stephen Hawking (who has died since) and British astronomer royal Martin Rees.

    Breakthrough Listen Project

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    UC Observatories Lick Autmated Planet Finder, fully robotic 2.4-meter optical telescope at Lick Observatory, situated on the summit of Mount Hamilton, east of San Jose, California, 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


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

    Newly added

    CfA/VERITAS, a major ground-based gamma-ray observatory with an array of four 12m optical reflectors for gamma-ray astronomy in the GeV – TeV energy range. Located at Fred Lawrence Whipple Observatory, Mount Hopkins, Arizona, US in AZ, USA, Altitude 2,606 m (8,550 ft)

    Echoing the film Contact, with Jodie Foster playing an astronomer listening out for broadcasts from aliens (loosely based on real-life SETI astronomer Jill Tarter), the project uses radio telescopes around the world to look for any signals from extraterrestrial intelligence.

    Jill Tarter Image courtesy of Jill Tarter

    After the Breakthrough Initiatives were announced, Milner’s money quickly got invested into the deployment of cutting-edge technology—such as computer storage and new receivers—at existing radio telescopes, including Green Bank in West Virginia and Parkes in Australia; whether the astronomers using these observatories believed in alien life or not, they welcomed the investment with open arms. It didn’t take long to receive the first scientific returns.

    After the Breakthrough Initiatives were announced, Milner’s money quickly got invested into the deployment of cutting-edge technology—such as computer storage and new receivers—at existing radio telescopes, including Green Bank in West Virginia and Parkes in Australia; whether the astronomers using these observatories believed in alien life or not, they welcomed the investment with open arms. It didn’t take long to receive the first scientific returns.

    In August 2015 one of the previously spotted FRBs decided to make a repeat appearance, triggering headlines worldwide because it was so incredibly powerful, brighter than the Lorimer Burst and any other FRB. It was dubbed “the repeater” and is also known as the Spitler Burst, because it was first discovered by astronomer Laura Spitler of the Max Planck Institute for Radio Astronomy in Bonn, Germany.

    Max Planck Institute for Radio Astronomy

    Max Planck Institute for Radio Astronomy Bonn Germany

    Over the next few months, the burst flashed many more times, not regularly, but often enough to allow researchers to determine its host galaxy and consider its possible source—likely a highly magnetized, young, rapidly spinning neutron star (or magnetar).

    This localization was done with the Very Large Array (VLA), a group of 27 radio dishes in New Mexico that feature heavily in the film Contact. But the infrastructure at Green Bank Telescope upgraded by Breakthrough Listen caught the repeating flashes many more times, says Lorimer—allowing researchers to study its host galaxy more in detail. “It’s wonderful—they have a mission to find ET, but along the way they want to show that this is producing other useful results for the scientific community,” he adds. Detecting FRBs has quickly become one of the main objectives of Breakthrough Listen.

    Netting the repeater was both a boon and a hindrance—on the one hand, it eliminated models that cataclysmic events such as supernova explosions were causing FRBs; after all, these can happen only once. On the other hand, it deepened the mystery. The repeater lives in a small galaxy with a lot of star formation—the kind of environment where a neutron star could be born, hence the magnetar model. But what about all the other FRBs that don’t repeat?

    Researchers started to think that perhaps there were different types of these bursts, each with its own source. Scientific conferences still buzz with talks of mights and might-nots, with physicists eagerly debating possible sources of FRBs in corridors and at conference bars. In March 2017, Loeb caused a media frenzy by suggesting that FRBs could actually be of alien origin—solar-powered radio transmitters that might be interstellar light sails pushing huge spaceships across galaxies.

    That Parkes is part of the SETI project is obvious to any visitor. Walking up the flight of stairs to the circular operating tower below the dish, every button, every door, and every wall nostalgically screams 1960s, until you reach the control room full of modern screens where astronomers remotely control the antenna to observe pulsars.

    Up another flight of stairs is the data storage room, stacked with columns and columns of computer drives full of blinking lights. One thick column of hard drives is flashing neon blue, put there by Breakthrough Listen as part of a cutting-edge recording system designed to help astronomers search for every possible radio signal in 12 hours of data, much more than ever before. Bailes, who now splits his time between FRB search and Breakthrough Listen, takes a smiling selfie in front of Milner’s drives.

    While many early FRB discoveries were made with veteran telescopes—single mega dishes like Parkes and Green Bank—new telescopes, some with the financial backing of Breakthrough Listen, are now revolutionizing the FRB field.

    Deep in South African’s semi-desert region of the Karoo, eight hours by car from Cape Town, stands an array of 64 dishes, permanently tracking space. They are much smaller than their mega-dish cousins, and all work in unison. This is MeerKAT [above], another instrument in Breakthrough Listen’s growing worldwide network of giant telescopes. Together with a couple of other next-generation instruments, this observatory might hopefully tell us one day, probably in the next decade, what FRBs really are.

    The name MeerKAT means “More KAT,” a follow up to KAT 7, the Karoo Array Telescope of seven antennas—although real meerkats do lurk around the remote site, sharing the space with wild donkeys, horses, snakes, scorpions and kudus, moose-sized mammals with long, spiraling antlers. Visitors to MeerKAT are told to wear safety leather boots with steel toes as a precaution against snakes and scorpions. They’re also warned about the kudus, which are very protective of their calves and recently attacked the pickup truck of a security guard, turning him and his car over. Around MeerKAT there is total radio silence; all visitors have to switch off their phones and laptops. The only place with connectivity is an underground “bunker” shielded by 30-centimeter-thick walls and a heavy metal door to protect the sensitive antennas from any human-made interference.

    MeerKAT is one of the two precursors to a much bigger future radio observatory—the SKA, or Square Kilometer Array.

    SKA Square Kilometer Array

    SKA South Africa

    Once SKA is complete, scientists will have added another 131 antennas in the Karoo. The first SKA dish has just been shipped to the MeerKAT site from China. Each antenna will take several weeks to assemble, followed by a few more months of testing to see whether it actually works the way it should. If all goes well, more will be commissioned, built, and shipped to this faraway place, where during the day the dominant color is brown; as the sun sets, however, the MeerKAT dishes dance in an incredible palette of purples, reds, and pinks, as they welcome the Milky Way stretching its starry path just above. MeerKAT will soon be an incredible FRB machine, says Bailes.

    There is another SKA precursor—ASKAP in Australia.

    Australian Square Kilometre Array Pathfinder (ASKAP) is a radio telescope array located at Murchison Radio-astronomy Observatory (MRO) in the Australian Mid West. ASKAP consists of 36 identical parabolic antennas, each 12 metres in diameter, working together as a single instrument with a total collecting area of approximately 4,000 square metres.

    Back in 2007, when Lorimer was mulling over the Nature rejection, Ryan Shannon was finishing his PhD in physics at Cornell University in New York—sharing the office with Laura Spitler, who would later discover the Spitler Burst. Shannon had come to the US from Canada, growing up in a small town in British Columbia. About half an hour drive from his home is the Dominion and Radio Astronomical Observatory (DRAO)—a relatively small facility that was involved in building equipment for the VLA.

    5

    NRAO/Karl V Jansky Expanded Very Large Array, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

    Subconsciously, says Shannon, DRAO must have impacted his choice of career. And it was at DRAO that a few years later a totally new telescope—Chime [above]—would be built that would greatly impact the nascent field of FRB research. But in 2007 that was still to come. After graduating from Cornell in 2011, Shannon decided not to stay close to home—“something my mum would’ve wanted.” Instead, he moved to Australia and ultimately to Swinburne University on the outskirts of Melbourne.

    Shannon joined Bailes’ team in 2017—and by then astronomers had begun to understand why they weren’t detecting more FRBs, even though they were already estimating that these flashes were happening hundreds of times every day, if not more. “Our big radio telescopes don’t have wide fields of view, they can’t see the entire sky—that’s why we missed nearly all FRBs in the first decade of realizing these things exist,” says Shannon.

    When he, Bailes, and other FRB hunters saw the ultra-bright repeater, the Spitler Burst, they understood that there were fast radio bursts which could be found even without gigantic telescopes like Parkes, by using instruments that have a wider field of view. So they started building ASKAP [above]—a new observatory conceived in 2012 and recently completed in the remote Australian outback. It sports 36 dishes with a 12-meter diameter each, and just like with MeerKAT, they all work together.

    To get to ASKAP, in a very sparsely populated area in the Murchison Shire of Western Australia, one has to first fly to Perth, change for a smaller plane bound for Murchison, then squeeze into a really tiny single propeller plane, or drive for five hours across 150 kilometers of dirt roads. “When it rains, it turns to mud, and you can’t drive there,” says Shannon, who went to the ASKAP site twice, to introduce the local indigenous population to the new telescope constructed—with permission—on their land and see the remote, next-generation ultra-sensitive radio observatory for himself.

    MeerKAT and ASKAP bring two very different technological approaches to the hunt for FRBs. Both observatories look at the southern sky, which makes it possible to see the Milky Way’s bright core much better than in the northern hemisphere; they complement old but much upgraded observatories like Parkes and Arecibo in South America. But the MeerKAT dishes have highly sensitive receivers which are able to detect very distant objects, while ASKAP’s novel multi-pixel receivers on each dish offer a much wider field of view, enabling the telescope to find nearby FRBs more often.

    “ASKAP’s dishes are less sensitive, but we can observe a much larger portion of the sky,” says Shannon. “So ASKAP is going to be able to see things that are usually intrinsically brighter.” Together, the two precursors will be hunting for different parts of the FRB population—since “you want to understand the entire population to know the big picture.”

    MeerKAT only started taking data in February, but ASKAP has been busy scanning the universe for FRBs for a few years now. Not only has it already spotted about 30 new bursts, but in a new paper just released in Science, Shannon and colleagues have detailed a new way to localize them despite their short duration, which is a big and important step toward being able to determine what triggers this ultra-bright radiation. Think of ASKAP’s antennas as the eye of a fly; they can scan a wide patch of the sky to spot as many bursts as possible, but the antennas can all be made to point instantly in the same direction. This way, they make an image of the sky in real time, and spot a millisecond-long FRB as it washes over Earth. That’s what Shannon and his colleagues have done, and for the first time ever, managed to net one burst they named FRB 180924 and pinpoint its host galaxy, some 4 billion light-years away, all in real time.

    Another team, at Caltech’s Owens Valley Radio Observatory (OVRO) in the Sierra Nevada mountains in California, have also just caught a new burst and traced it back to its source, a galaxy 7.9 billion light years away.

    Caltech’s Deep Synoptic Array 10 dish array at Owens Valley Radio Observatory, near Big Pine, California USA, Altitude 1,222 m (4,009 ft

    And just like Shannon, they didn’t do it with a single dish telescope but a recently built array of 10 4.5-meter antennas called the Deep Synoptic Array-10. The antennas act together like a mile-wide dish to cover an area on the sky the size of 150 full moons. The telescope’s software then processes an amount of data equivalent to a DVD every second. The array is a precursor for the Deep Synoptic Array that, when built by 2021, will sport 110 radio dishes, and may be able to detect and locate more than 100 FRBs every year.

    What both ASKAP’s and OVRO’s teams found was that their presumably one-off bursts originated in galaxies very different from the home of the first FRB repeater. Both come from galaxies with very little star formation, similar to the Milky Way and very different from the home of the repeater, where stars are born at a rate of about a hundred times faster. The discoveries show that “every galaxy, even a run-of-the-mill galaxy like our Milky Way, can generate an FRB,” says Vikram Ravi, an astronomer at Caltech and part of the OVRO team.

    But the findings also mean that the magnetar model, accepted by many as the source of the repeating burst, does not really work for these one-off flashes. Perhaps, Shannon says, ASKAP’s burst could be the result of a merger of two neutron stars, similar to the one spotted two years ago by the gravitational wave detectors LIGO and Virgo in the US and Italy, because both host galaxies are very similar. “It’s a bit spooky that way,” says Shannon. One thing is clear though, he adds: The findings show that there is likely more than one type of FRBs.

    Back in Shannon’s hometown in Canada, the excitement has also been growing exponentially because of CHIME. Constructed at the same time as MeerKAT and ASKAP, this is a very different observatory; it has no dishes but antennas in the form of long buckets designed to capture light. In January, the CHIME team reported the detection of the second FRB repeater and 12 non-repeating FRBs. CHIME is expected to find many, many more bursts, and with ASKAP, MeerKAT and CHIME working together, astronomers hope to understand the true nature of the enigmatic radio flashes very soon.

    But will they fulfill Milner’s dream and successfully complete SETI, the search for extraterrestrial intelligence? Lorimer says that scientists hunting for FRBs and pulsars have for decades been working closely with colleagues involved in SETI projects.

    After all, Loeb’s models for different—alien—origins of FRBs are not fundamentally wrong. “The energetics when you consider what we know from the observations are consistent and there’s nothing wrong with that,” says Lorimer. “And as part of the scientific method, you definitely want to encourage those ideas.” He personally prefers to find the simplest natural explanation for the phenomena he observes in space—but until we manage to directly observe the source of these FRBs, all theoretical ideas should stand, as long as they are scientifically sound—whether they involve aliens or not.

    Any image repeats in this post were required for complete coverage.

    See the full article here .

    Totally missing from this article on SETI-

    SETI Institute


    SETI/Allen Telescope Array situated at the Hat Creek Radio Observatory, 290 miles (470 km) northeast of San Francisco, California, USA, Altitude 986 m (3,235 ft)

    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).jpg

    Shelley Wright of UC San Diego, with NIROSETI, developed at U Toronto, at the 1-meter Nickel Telescope at Lick Observatory at UC Santa Cruz

    Laser SETI, the future of SETI Institute research

    SETI@home, a BOINC project originated in the Space Science Lab at UC Berkeley

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  • richardmitnick 9:53 am on July 21, 2019 Permalink | Reply
    Tags: , , , Cecilia Payne, , , , Payne discovered that hydrogen and helium are the dominant elements of the stars -1925 Ph.D. thesis., ,   

    From COSMOS Magazine: Women in STEM- “This week in science history: The woman who found hydrogen in the stars is born” Cecilia Payne 

    Cosmos Magazine bloc

    From COSMOS Magazine

    THIS POST IS DEDICATED TO L.Z. OF RUTGERS PHYSICS AND HP, WHO BROUGHT CECILIA PAYNE TO MY ATTENTION. I HOPE HE SEES THIS. IF HE SEES IT, HE CAN ADVISE ME BY EMAIL.

    1
    Meet the Woman Who Discovered the Composition of the Stars, Cecilia Payne. Mental Floss, Caitlin Schneider August 26, 2015

    Cecilia Payne is today recognised as an equal to Newton and Einstein, but it wasn’t always so.

    10 May 2018
    Jeff Glorfeld

    2
    Cecilia Payne, photographed in 1951. Bettmann / Contributor / Getty Images

    Cecilia Payne, born on May 10, 1900, in Wendover, England, began her scientific career in 1919 with a scholarship to Cambridge University, where she studied physics. But in 1923 she received a fellowship to move to the United States and study astronomy at Harvard. Her 1925 thesis, Stellar Atmospheres, was described at the time by renowned Russian-American astronomer Otto Struve as “the most brilliant PhD thesis ever written in astronomy”.

    In the January, 2015, Richard Williams of the American Physical Society, wrote: “By calculating the abundance of chemical elements from stellar spectra, her work began a revolution in astrophysics.”

    In 1925 Payne received the first PhD in astronomy from Radcliffe, Harvard’s college for women, – because Harvard itself did not grant doctoral degrees to women.

    In the early 1930s she met Sergey Gaposchkin, a Russian astronomer who could not return to the Soviet Union because of his politics. Payne was able to find a position at Harvard for him. They married in 1934.

    Finally, in 1956, she achieved two Harvard firsts: she became its first female professor, and the first woman to become department chair.

    In a 2016 article about Payne for New York magazine, writer Dava Sobel reports that when she arrived at Harvard, Payne found the school had a collection of several hundred thousand glass photographs of the night sky, taken over a period of 40 years. Many of these images stretched starlight into strips, or spectra, marked by naturally occurring lines that revealed the constituent elements.

    As she painstakingly examined these plates, Payne reached her controversial – and groundbreaking – conclusion: that unlike on Earth, hydrogen and helium are the dominant elements of the stars.

    At the time, most scientists believed that because stars contained familiar elements such as silicon, aluminium and iron, similar to Earth’s make-up, they would be present in the same proportions, with only small amounts of hydrogen.

    Although the presence of hydrogen in stars had been known since the 1860s, when chemical analysis at a distance first became possible, no one expected the great abundance claimed by Payne.

    Richard Williams, writing for the American Physical Society in 2015, said: “The giants – Copernicus, Newton, and Einstein – each in his turn, brought a new view of the universe. Payne’s discovery of the cosmic abundance of the elements did no less.”

    However, at the time of her thesis publication the foremost authority on stellar composition, Henry Norris Russell, of Princeton University, convinced Payne that her conclusions had to be wrong, encouraging her write that her percentages of hydrogen and helium were “improbably high” and therefore “almost certainly not real”.

    But in brilliant vindication, Russell devoted the next four years to studying Payne’s findings, and in the issue of the Astrophysical Journal, he agreed with her and cited her 1925 study, concluding for the record that the great abundance of hydrogen “can hardly be doubted”.

    Cecilia Payne-Gaposchkin died on December 7, 1979.

    See the full article here .


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  • richardmitnick 7:13 am on July 21, 2019 Permalink | Reply
    Tags: "Where Do Supermassive Black Holes Come From?", , , , Caltech/MIT Advanced aLigo and Advanced VIRGO, , , , , ,   

    From Western University, CA and WIRED: “Where Do Supermassive Black Holes Come From?” 

    From Western University Canada

    2
    Scott Woods, Western University, Illustration of supermassive black hole
    via

    WIRED

    Wired logo
    NASA

    June 28, 2019

    Researchers decipher the history of supermassive black holes in the early universe.

    At Western University
    MEDIA CONTACT:
    Jeff Renaud, Senior Media Relations Officer,
    519-661-2111, ext. 85165,
    519-520-7281 (mobile),
    jrenaud9@uwo.ca, @jeffrenaud99

    07.18.19
    From Wired
    Meredith Fore

    1
    NASA

    A pair of researchers at Western University in Ontario, Canada, developed their model by looking at quasars, which are supermassive black holes.

    Astronomers have a pretty good idea of how most black holes form: A massive star dies, and after it goes supernova, the remaining mass (if there’s enough of it) collapses under the force of its own gravity, leaving behind a black hole that’s between five and 50 times the mass of our Sun. What this tidy origin story fails to explain is where supermassive black holes, which range from 100,000 to tens of billions of times the mass of the Sun, come from. These monsters exist at the center of almost all galaxies in the universe, and some emerged only 690 million years after the Big Bang. In cosmic terms, that’s practically the blink of an eye—not nearly long enough for a star to be born, collapse into a black hole, and eat enough mass to become supermassive.

    One long-standing explanation for this mystery, known as the direct-collapse theory, hypothesizes that ancient black holes somehow got big without the benefit of a supernova stage. Now a pair of researchers at Western University in Ontario, Canada—Shantanu Basu and Arpan Das—have found some of the first solid observational evidence for the theory. As they described late last month in The Astrophysical Journal Letters, they did it by looking at quasars.

    Quasars are supermassive black holes that continuously suck in, or accrete, large amounts of matter; they get a special name because the stuff falling into them emits bright radiation, making them easier to observe than many other kinds of black holes. The distribution of their masses—how many are bigger, how many are smaller, and how many are in between—is the main indicator of how they formed.

    Astrophysicists at Western University have found evidence for the direct formation of black holes that do not need to emerge from a star remnant. The production of black holes in the early universe, formed in this manner, may provide scientists with an explanation for the presence of extremely massive black holes at a very early stage in the history of our universe.

    After analyzing that information, Basu and Das proposed that the supermassive black holes might have arisen from a chain reaction. They can’t say exactly where the seeds of the black holes came from in the first place, but they think they know what happened next. Each time one of the nascent black holes accreted matter, it would radiate energy, which would heat up neighboring gas clouds. A hot gas cloud collapses more easily than a cold one; with each big meal, the black hole would emit more energy, heating up other gas clouds, and so on. This fits the conclusions of several other astronomers, who believe that the population of supermassive black holes increased at an exponential rate in the universe’s infancy.

    “This is indirect observational evidence that black holes originate from direct-collapses and not from stellar remnants,” says Basu, an astronomy professor at Western who is internationally recognized as an expert in the early stages of star formation and protoplanetary disk evolution.

    Basu and Das developed the new mathematical model by calculating the mass function of supermassive black holes that form over a limited time period and undergo a rapid exponential growth of mass. The mass growth can be regulated by the Eddington limit that is set by a balance of radiation and gravitation forces or can even exceed it by a modest factor.

    “Supermassive black holes only had a short time period where they were able to grow fast and then at some point, because of all the radiation in the universe created by other black holes and stars, their production came to a halt,” explains Basu. “That’s the direct-collapse scenario.”

    But at some point, the chain reaction stopped. As more and more black holes—and stars and galaxies—were born and started radiating energy and light, the gas clouds evaporated. “The overall radiation field in the universe becomes too strong to allow such large amounts of gas to collapse directly,” Basu says. “And so the whole process comes to an end.” He and Das estimate that the chain reaction lasted about 150 million years.

    The generally accepted speed limit for black hole growth is called the Eddington rate, a balance between the outward force of radiation and the inward force of gravity. This speed limit can theoretically be exceeded if the matter is collapsing fast enough; the Basu and Das model suggests black holes were accreting matter at three times the Eddington rate for as long as the chain reaction was happening. For astronomers regularly dealing with numbers in the millions, billions, and trillions, three is quite modest.

    “If the numbers had turned out crazy, like you need 100 times the Eddington accretion rate, or the production period is 2 billion years, or 10 years,” Basu says, “then we’d probably have to conclude that the model is wrong.”

    There are many other theories for how direct-collapse black holes could be created: Perhaps halos of dark matter formed ultramassive quasi-stars that then collapsed, or dense clusters of regular mass stars merged and then collapsed.

    For Basu and Das, one strength of their model is that it doesn’t depend on how the giant seeds were created. “It’s not dependent on some person’s very specific scenario, specific chain of events happening in a certain way,” Basu says. “All this requires is that some very massive black holes did form in the early universe, and they formed in a chain reaction process, and it only lasted a brief time.”

    The ability to see a supermassive black hole forming is still out of reach; existing telescopes can’t look that far back yet. But that may change in the next decade as powerful new tools come online, including the James Webb Space Telescope, the Wide Field Infrared Survey Telescope, and the Laser Interferometer Space Antenna—all of which will hover in low Earth orbit—as well as the Large Synoptic Survey Telescope, based in Chile.

    NASA/ESA/CSA Webb Telescope annotated

    NASA/WFIRST

    Gravity is talking. Lisa will listen. Dialogos of Eide

    ESA/LISA Pathfinder

    ESA/NASA eLISA space based, the future of gravitational wave research

    LSST Camera, built at SLAC

    LSST telescope, currently under construction at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    In the next five or 10 years, Basu adds, as the “mountain of data” comes in, models like his and his colleague’s will help astronomers interpret what they see.

    Avi Loeb, one of the pioneers of direct-collapse black hole theory and the director of the Black Hole Initiative at Harvard, is especially excited for the Laser Interferometer Space Antenna. Set to launch in the 2030s, it will allow scientists to measure gravitational waves—fine ripples in the fabric of space-time—more accurately than ever before.

    “We have already started the era of gravitational wave astronomy with stellar-mass black holes,” he says, referring to the black hole mergers detected by the ground-based Laser Interferometer Gravitational-Wave Observatory.

    Its space-based counterpart, Loeb anticipates, could provide a better “census” of the supermassive black hole population.

    For Basu, the question of how supermassive black holes are created is “one of the big chinks in the armor” of our current understanding of the universe. The new model “is a way of making everything work according to current observations,” he says. But Das remains open to any surprises delivered by the spate of new detectors—since surprises, after all, are often how science progresses.

    MIT /Caltech Advanced aLigo



    VIRGO Gravitational Wave interferometer, near Pisa, Italy


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    LSC LIGO Scientific Collaboration


    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project

    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger

    Gravity is talking. Lisa will listen. Dialogos of Eide

    ESA/eLISA the future of gravitational wave research

    Localizations of gravitational-wave signals detected by LIGO in 2015 (GW150914, LVT151012, GW151226, GW170104), more recently, by the LIGO-Virgo network (GW170814, GW170817). After Virgo came online in August 2018


    Skymap showing how adding Virgo to LIGO helps in reducing the size of the source-likely region in the sky. (Credit: Giuseppe Greco (Virgo Urbino group)

    See the full WIRED article here .
    See the full Western University article here .

    The University of Western Ontario (UWO), corporately branded as Western University as of 2012 and commonly shortened to Western, is a public research university in London, Ontario, Canada. The main campus is on 455 hectares (1,120 acres) of land, surrounded by residential neighbourhoods and the Thames River bisecting the campus’s eastern portion. The university operates twelve academic faculties and schools. It is a member of the U15, a group of research-intensive universities in Canada.

    The university was founded on 7 March 1878 by Bishop Isaac Hellmuth of the Anglican Diocese of Huron as the Western University of London, Ontario. It incorporated Huron University College, which had been founded in 1863. The first four faculties were Arts, Divinity, Law and Medicine. The Western University of London became non-denominational in 1908. Beginning in 1919, the university has affiliated with several denominational colleges. The university grew substantially in the post-World War II era, as a number of faculties and schools were added to university.

    Western is a co-educational university, with more than 24,000 students, and with over 306,000 living alumni worldwide. Notable alumni include government officials, academics, business leaders, Nobel Laureates, Rhodes Scholars, and distinguished fellows. Western’s varsity teams, known as the Western Mustangs, compete in the Ontario University Athletics conference of U Sports.

    Wired logo

    WIRED

    See the full article here .

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  • richardmitnick 12:28 pm on July 20, 2019 Permalink | Reply
    Tags: "Ask Ethan: What Does ‘Truth’ Mean To A Scientist?", , , , ,   

    From Ethan Siegel: “Ask Ethan: What Does ‘Truth’ Mean To A Scientist?” 

    From Ethan Siegel
    July 20 2019

    1
    If you look farther and farther away, you also look farther and farther into the past. The farthest we can see back in time is 13.8 billion years: our estimate for the age of the Universe. It’s the extrapolation back to the earliest times that led to the idea of the Big Bang. While everything we observe is consistent with the Big Bang framework, it’s not something that can ever be proven. (NASA / STSCI / A. FELID)

    NASA/ESA Hubble Telescope

    It’s very different from the colloquial meanings of “true-and-false” or “right-and-wrong.”

    In many ways, the human endeavor of science is the ultimate pursuit of truth. By asking the natural world and Universe questions about itself, we seek to gain an understanding of what the Universe is like, what the rules that govern it are, and how things came to be the way they are today. Science is the full suite of knowledge that we gain from observing, measuring, and performing experiments that test the Universe, but it’s also the process through which we perform those investigations. It might be easy to see how we gain knowledge from that endeavor, but how do scientists arrive at the idea of a scientific truth? That’s Curtis Brand’s question, as he asks:

    I was speaking to a friend [who’s] an economic analyst, and his personal definition of a truth was when something’s 51%+ likely to happen… In science, do you ever truly accept anything as a truth, and if so, on what grounds do you typically decide its worthy of being called “true”?

    When we’re speaking scientifically, “truth” is something very different than how we colloquially use it. Here’s how.

    2
    One of the great puzzles of the 1500s was how planets moved in an apparently retrograde fashion. This could either be explained through Ptolemy’s geocentric model (L), or Copernicus’ heliocentric one (R). However, getting the details right to arbitrary precision was something that would require theoretical advances in our understanding of the rules underlying the observed phenomena, which led to Kepler’s laws and eventually Newton’s theory of universal gravitation. (ETHAN SIEGEL / BEYOND THE GALAXY)

    Let’s consider the following statement: “the Earth is round.” If you’re not a scientist (and also not a flat-Earther), you might think that this statement is unimpeachable. You might think of this as being scientifically true. In fact, stating that the Earth is round is a valid scientific conclusion and a scientific fact, at least if you contrast a round Earth with a flat Earth.

    But there’s always an additional nuance and caveat at play. If you were to measure the diameter of the Earth across our equator, you’d get a value: 7,926 miles (12,756 km). If you measured the diameter from the north pole to the south pole, you’d get a slightly different value: 7,900 miles (12,712 km). The Earth is not a perfect sphere, but rather a near-spherical shape that bulges at the equator and is compressed at the poles.

    3
    Planet Earth, viewed in its entirety (as much as one can see at once) from the GOES-13 satellite. In this image, the planet may appear to be perfectly spherical, but its equatorial diameter is slightly larger than its polar diameter: Earth is more accurately approximated by an oblate spheroid than by a perfectly round sphere. (NASA / GODDARD SPACE FLIGHT CENTER / GOES-13 / NOAA)

    4
    NOAA GOES R satellite with Earth

    To a scientist, this illustrates extremely well the caveats associated with a term like scientific truth. Sure, it’s more true that the Earth is a sphere than that the Earth is a disc or a circle. But it isn’t an absolute truth that the Earth is a sphere, because it’s more correct to call it an oblate spheroid than a sphere. And even if you do, calling it an oblate spheroid isn’t the absolute truth, either.

    There are surface features on Earth that demonstrate significant departures from a smooth shape like either a sphere or an oblate spheroid. There are mountain ranges, rivers, valleys, plateaus, deep oceans, trenches, ridges, volcanoes and more. There are locations where the land extends more than 29,000 feet (nearly 9,000 meters) above sea level, and places where you won’t touch the Earth’s surface until you’re 36,000 feet (11,000 meters) beneath the ocean’s surface.

    There are a few important ways of thinking scientifically that differ from how we think colloquially.

    There are no absolute truths in science; there are only approximate truths.
    Whether a statement, theory, or framework is true or not depends on quantitative factors and how closely you examine or measure the results.
    Every scientific theory has a finite range of validity: inside that range, the theory is indistinguishable from true, outside of that range, the theory is no longer true.

    This represents an enormous difference from how we commonly think about fact vs. fiction, truth vs. falsehood, or even right vs. wrong.

    5
    According to legend, the first experiment to show that all objects fell at the same rate, irrespective of mass, was performed by Galileo Galilei atop the Leaning Tower of Pisa. Any two objects dropped in a gravitational field, in the absence of (or neglecting) air resistance, will accelerate down to the ground at the same rate. This was later codified as part of Newton’s investigations into the matter, which superseded the earlier notions of a constant downward acceleration, which apply only to the surface of the Earth. (GETTY IMAGES)

    For example, if you drop a ball on Earth, you can ask the quantitative, scientific question of how it will behave. Like everything on Earth’s surface, it will accelerate downwards at 9.8 m/s² (32 ft/s²). And this is a great answer, because it’s approximately true.

    In science, though, you can start looking more deeply, and seeing where this approximation is no longer true. If you perform this experiment at sea level, at a variety of latitudes, you’ll find that this answer actually varies: from 9.79 m/s² at the equator to 9.83 m/s² at the poles. If you go to higher altitudes, you’ll find that the acceleration starts to slowly decrease. And if you leave the Earth’s gravitational pull, you’ll find that this rule isn’t universal at all, but is rather superseded by a more general rule: the law of Universal gravitation.

    5
    The Apollo mission trajectories, made possible by the Moon’s close proximity to us. Newton’s law of universal gravitation, despite the fact that it’s been superseded by Einstein’s General Relativity, is still so good at being approximately true on most Solar System scales that it encapsulates all the physics we need to travel from Earth to the Moon and land on its surface, and return. (NASA’S OFFICE OF MANNED SPACE FLIGHT, APOLLO MISSIONS)

    This laws is even more generally true. Newton’s law of universal gravitation can explain all the successes of modeling Earth’s acceleration as a constant, but it can also do much more. It can describe the orbital motion of the moons, planets, asteroids and comets of the solar system, as well as how much you’d weigh on any of the planets. It describes how the stars move around inside galaxies, and even allowed us to predict how to send a rocket to land humans on the Moon, with extraordinarily accurate trajectories.

    But even Newton’s law has its limits. When you move close to the speed of light, or get very close to an extremely large mass, or want to know what’s occurring on cosmic scales (such as in the case of the expanding Universe), Newton won’t help you. For that, you have to supersede Newton and move on to Einstein’s General Relativity.

    6
    An illustration of gravitational lensing showcases how background galaxies — or any light path — is distorted by the presence of an intervening mass, but it also shows how space itself is bent and distorted by the presence of the foreground mass itself. Before Einstein put forth his theory of General Relativity, he understood that this bending must occur, even though many remained skeptical until (and even after) the solar eclipse of 1919 confirmed his predictions. There is a significant difference between Einstein’s and Newton’s predictions for the amount of bending that should occur, due to the fact that space and time are both affected by mass in General Relativity. (NASA/ESA)

    Gravitational Lensing NASA/ESA

    For the trajectories of particles moving close to the speed of light, or to obtain very accurate predictions for the orbit of Mercury (the Solar System’s closest and fastest planet), or to explain the gravitational bending of starlight by the Sun (during an eclipse) or by a large collection of mass (such as in the case of gravitational lensing, above), Einstein’s theory gets it right where Newton’s fails. In fact, for every observational or experimental test we’ve thrown at General Relativity, from gravitational waves to the frame-dragging of space itself, it’s passed with flying colors.

    Does that mean that Einstein’s theory of General Relativity can be taken as a scientific truth?

    When you apply it to these specific scenarios, absolutely. But there are other scenarios we can apply it to, all of which are not yet sufficiently tested, where we fully expect that it won’t give quantitatively accurate predictions.

    8
    Even two merging black holes, one of the strongest sources of a gravitational signal in the Universe, doesn’t leave an observable signature that could probe quantum gravity. For that, we’ll have to create experiments that probe either the strong-field regime of relativity, i.e., near the singularity, or that take advantage of clever laboratory setups. (SXS, THE SIMULATING EXTREME SPACETIMES (SXS) PROJECT (BLACK-HOLES.ORG))
    The SXS project is a collaborative research effort involving multiple institutions. Our goal is the simulation of black holes and other extreme spacetimes to gain a better understanding of Relativity, and the physics of exotic objects in the distant cosmos.
    The SXS project is supported by Canada Research Chairs, CFI, CIfAR, Compute Canada, Max Planck Society, NASA, NSERC, the NSF, Ontario MEDI, the Sherman Fairchild Foundation, and XSEDE.

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    There are many questions we can ask about reality that require us to understand what’s happening where gravity is important or where the curvature of spacetime is extremely strong: just where you’d want Einstein’s theory. But when the distance scales you’re thinking about are also very small, you expect quantum effects to be important as well, and General Relativity cannot account for those. These include questions such as the following:

    What happens to the gravitational field of an electron when it passes through a double slit?
    What happens to the information of the particles that form a black hole, if the black hole’s eventual state is to decay into thermal radiation?
    And what is the behavior of a gravitational field/force at and around a singularity?

    Einstein’s theory won’t just get these answers wrong, it won’t have sensible answers to offer. In these regimes, we know we require a more advanced theory, such as a valid quantum gravitational theory, to tell us what’s going to happen under these circumstances.

    20
    Encoded on the surface of the black hole can be bits of information, proportional to the event horizon’s surface area. When the black hole decays, it decays to a state of thermal radiation. Whether that information survives and is encoded in the radiation or not, and if so, how, is not a question that our current theories can provide the answer to. (T.B. BAKKER / DR. J.P. VAN DER SCHAAR, UNIVERSITEIT VAN AMSTERDAM)

    Yes, masses at the surface of Earth accelerate downwards at 9.8 m/s², but if we ask the right questions or perform the right observations or experiments, we can find where and how this description of reality is no longer a good approximation of the truth. Newton’s laws can explain that phenomenon and many others, but we can find observations and experiments that show us where Newton, too, is insufficient.

    Even replacing Newton’s laws with Einstein’s General Relativity leads to the same story: Einstein’s theory can successfully explain everything that Newton’s can, plus additional phenomena. Some of those phenomena were already known when Einstein was constructing his theory; others had not yet been tested. But we can be certain that even Einstein’s greatest accomplishment will someday be superseded. When it does, we fully expect it will happen in exactly the same way.

    21
    Quantum gravity tries to combine Einstein’s General theory of Relativity with quantum mechanics. Quantum corrections to classical gravity are visualized as loop diagrams, as the one shown here in white. Whether space (or time) itself is discrete or continuous is not yet decided, as is the question of whether gravity is quantized at all, or particles, as we know them today, are fundamental or not. But if we hope for a fundamental theory of everything, it must include quantized fields, which General Relativity does not do on its own. (SLAC NATIONAL ACCELERATOR LAB)

    Science is not about finding the absolute truth of the Universe. No matter how much we’d like to know what the fundamental nature of reality is, from the smallest subatomic scales to the largest cosmic ones and beyond, this is not something science can deliver. All of our scientific truths are provisional, and we must recognize that they are only models or approximation of reality.

    Even the most successful scientific theories imaginable will, by their very nature, have a limited range of validity. But we can theorize whatever we like, and when a new theory meets the following three criteria:

    it achieves all of the successes of the prevailing, pre-existing theory,
    it succeeds where the current theory is known to fail,
    and it makes novel predictions for hitherto unmeasured phenomena, distinct from the prior theory, that pass the critical observational or experimental tests,

    it will supersede the current one as our best approximation of a scientific truth.

    Inflationary Universe. NASA/WMAP

    All of our currently held scientific truths, from the Standard Model of elementary particles to the Big Bang to dark matter and dark energy to cosmic inflation and beyond, are only provisional.

    Standard Model of Particle Physics (LATHAM BOYLE AND MARDUS OF WIKIMEDIA COMMONS)

    Coma cluster via NASA/ESA Hubble, the original example of Dark Matter discovered during observations by Fritz Zwicky and confirmed by Vera Rubin

    Dark Energy Camera Enables Astronomers a Glimpse at the Cosmic Dawn. CREDIT National Astronomical Observatory of Japan



    Dark Energy Camera Enables Astronomers a Glimpse at the Cosmic Dawn. CREDIT National Astronomical Observatory of Japan

    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex Mittelmann Cold creation

    They describe the Universe extremely accurately, succeeding in regimes where all prior frameworks have failed. Yet they all have limitations to how far we can take their implications before we arrive at a place where their predictions are no longer sensible, or no longer describe reality. They are not absolute truths, but approximate, provisional ones.

    No experiment can ever prove that a scientific theory is true; we can only demonstrate that its validity either extends or fails to extend to whatever regime we test it in. The failure of a theory is actually the ultimate scientific success: an opportunity to find an even better scientific truth to approximate reality. It’s being wrong in the best way imaginable.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 11:08 am on July 20, 2019 Permalink | Reply
    Tags: "Yes Virtual Particles Can Have Real Observable Effects", A neutron star despite being mostly made of neutral particles produces the strongest magnetic fields in the Universe., As particle-antiparticle pairs pop in-and-out of existence they can interact with real particles, , , , , , In 2016 scientists were able to locate a neutron star that was close enough and possessed a strong enough magnetic field to make these observations possible., On scales of both the very large and the very small we do far better by applying our best scientific theories extracting physical predictions and then observing and measuring the critical phenomena., , Real particles like electrons or photons leaving signatures imprinted on the real particles that are potentially observable., The light around RX J1856.5–3754 is just perfect., The nature of our quantum Universe is puzzling counterintuitive and testable. The results don’t lie., Vacuum birefringence, When you apply a strong magnetic field particles and antiparticles have opposite charges from one another., When you have particle/antiparticle pairs present in empty space you might think they simply pop into existence live for a little while and then re-annihilate and go back into nothingness.   

    From Ethan Siegel: “Yes, Virtual Particles Can Have Real, Observable Effects” 

    From Ethan Siegel
    July 19, 2019

    1
    As electromagnetic waves propagate away from a source that’s surrounded by a strong magnetic field, the polarization direction will be affected due to the magnetic field’s effect on the vacuum of empty space: vacuum birefringence. By measuring the wavelength-dependent effects of polarization around neutron stars with the right properties, we can confirm the predictions of virtual particles in the quantum vacuum. (N. J. SHAVIV / SCIENCEBITS)

    The nature of our quantum Universe is puzzling, counterintuitive, and testable. The results don’t lie.

    Although our intuition is an incredibly useful tool for navigating daily life, developed from a lifetime of experience in our own bodies on Earth, it’s often horrid for providing guidance outside of that realm. On scales of both the very large and the very small, we do far better by applying our best scientific theories, extracting physical predictions, and then observing and measuring the critical phenomena.

    Without this approach, we never would have come to understood the basic building blocks of matter, the relativistic behavior of matter and energy, or the fundamental nature of space and time themselves. But nothing matches the counterintuitive nature of quantum vacuum. Empty space isn’t completely empty, but consists of an indeterminate state of fluctuating fields and particles. It’s not science fiction; it’s a theoretical framework with testable, observable predictions. 80 years after Heisenberg first postulated an observational test, humanity has confirmed it. Here’s what we’ve learned.

    2
    An illustration between the inherent uncertainty between position and momentum at the quantum level. There is a limit to how well you can measure these two quantities simultaneously, and uncertainty shows up in places where people often least expect it. (E. SIEGEL / WIKIMEDIA COMMONS USER MASCHEN)

    Discovering that our Universe was quantum in nature brought with it a lot of unintuitive consequences. The better you measured a particle’s position, the more fundamentally indeterminate its momentum was. The shorter an unstable particle lived, the less well-known its mass fundamentally was. Material objects that appear to be solid on macroscopic scales can exhibit wave-like properties under the right experimental conditions.

    But empty space holds perhaps the top spot when it comes to a phenomenon that defies our intuition. Even if you remove all the particles and radiation from a region of space — i.e., all the sources of quantum fields — space still won’t be empty. It will consist of virtual pairs of particles and antiparticles, whose existence and energy spectra can be calculated. Sending the right physical signal through that empty space should have consequences that are observable.

    3
    An illustration of the early Universe as consisting of quantum foam, where quantum fluctuations are large, varied, and important on the smallest of scales. (NASA/CXC/M.WEISS)

    The particles that temporarily exist in the quantum vacuum themselves might be virtual, but their effect on matter or radiation is very real. When you have a region of space that particles pass through, the properties of that space can very much have real, physical effects that be predicted and tested.

    One of those effects is this: when light propagates through a vacuum, if space is perfectly empty, it should move through that space unimpeded: without bending, slowing, or breaking into multiple wavelengths. Applying an external magnetic field doesn’t change this, as photons, with their oscillatory electric and magnetic fields, don’t bend in a magnetic field. Even when your space is filled with particle/antiparticle pairs, this effect doesn’t change. But if you apply a strong magnetic field to a space filled with particle/antiparticle pairs, suddenly a real, observable effect arises.

    4
    Visualization of a quantum field theory calculation showing virtual particles in the quantum vacuum. (Specifically, for the strong interactions.) Even in empty space, this vacuum energy is non-zero. As particle-antiparticle pairs pop in-and-out of existence, they can interact with real particles like electrons or photons, leaving signatures imprinted on the real particles that are potentially observable. (DEREK LEINWEBER)

    When you have particle/antiparticle pairs present in empty space, you might think they simply pop into existence, live for a little while, and then re-annihilate and go back into nothingness. In empty space with no external fields, this is true: Heisenberg’s energy-time uncertainty principle applies, and so long as all the relevant conservation laws are still obeyed, this is all that happens.

    But when you apply a strong magnetic field, particles and antiparticles have opposite charges from one another. Particles with the same velocities but opposite charges will bend in opposite directions in the presence of a magnetic field, and light that passes through a region of space with charged particles that move in this particular fashion should exhibit an effect: it should get polarized. If the magnetic field is strong enough, this should lead to an observably large polarization, by an amount that’s dependent on the strength of the magnetic field.

    5
    There have been many attempts to measure the effect of vacuum birefringence in a laboratory setting, such as with a direct laser pulse setup as shown here. However, they have been unsuccessful so far, as the effects have been too small to be seen with terrestrial magnetic fields, even with gamma rays at the GeV scale.(YOSHIHIDE NAKAMIYA, KENSUKE HOMMA, TOSEO MORITAKA, AND KEITA SETO, VIA ARXIV.ORG/ABS/1512.00636)

    This effect is known as vacuum birefringence, occurring when charged particles get yanked in opposite directions by strong magnetic field lines. Even in the absence of particles, the magnetic field will induce this effect on the quantum vacuum (i.e., empty space) alone. The effect of this vacuum birefringence gets stronger very quickly as the magnetic field strength increases: as the square of the field strength. Even though the effect is small, we have places in the Universe where the magnetic field strengths get large enough to make these effects relevant.

    Earth’s natural magnetic field might only be ~100 microtesla, and the strongest human-made fields are still only about 100 T. But neutron stars give us the opportunity for particularly extreme conditions, giving us large volumes of space where the field strength exceeds 10⁸ (100 million) T, ideal conditions for measuring vacuum birefringence.

    6
    A neutron star, despite being mostly made of neutral particles, produces the strongest magnetic fields in the Universe, a quadrillion times stronger than the fields at the surface of Earth. When neutron stars merge, they should produce both gravitational waves and also electromagnetic signatures, and when they cross a threshold of about 2.5 to 3 solar masses (depending on spin), they can become black holes in under a second. (NASA / CASEY REED — PENN STATE UNIVERSITY)

    How do neutron stars make such large magnetic fields? The answer may not be what you think. Although it might be tempting to take the name ‘neutron star’ quite literally, it isn’t made exclusively out of neutrons. The outer 10% of a neutron star consists mostly of protons, light nuclei, and electrons, which can stably exist without being crushed at the neutron star’s surface.

    Neutron stars rotate extremely rapidly, frequently in excess of 10% the speed of light, meaning that these charged particles on the outskirts of the neutron star are always in motion, which necessitated the production of both electric currents and induced magnetic fields. These are the fields we should be looking for if we want to observe vacuum birefringence, and its effect on the polarization of light.

    7
    Light coming from the surface of a neutron star can be polarized by the strong magnetic field it passes through, thanks to the phenomenon of vacuum birefringence. Detectors here on Earth can measure the effective rotation of the polarized light. (ESO/L. CALÇADA)

    It’s a challenge to measure the light from neutron stars: although they’re quite hot, hotter even than normal stars, they’re tiny, with diameters of just a few dozen kilometers. A neutron star is like a glowing Sun-like star, at perhaps two or three times the temperature of the Sun, compressed into a volume the size of Washington, D.C.

    Neutron stars are very faint, but they do emit light from all across the spectrum, including all the way down into the radio part of the spectrum. Depending on where we choose to look, we can observe the wavelength-dependent effects that the effect of vacuum birefringence has on the light’s polarization.

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    VLT image of the area around the very faint neutron star RX J1856.5–3754. The blue circle, added by E. Siegel, shows the location of the neutron star. Note that despite appearing very faint and red in this image, there is enough light reaching our detectors for us, with the proper instrumentation, to search for this vacuum birefringence effect. (ESO)

    ESO VLT at Cerro Paranal in the Atacama Desert, •ANTU (UT1; The Sun ),
    •KUEYEN (UT2; The Moon ),
    •MELIPAL (UT3; The Southern Cross ), and
    •YEPUN (UT4; Venus – as evening star).
    elevation 2,635 m (8,645 ft) from above Credit J.L. Dauvergne & G. Hüdepohl atacama photo,


    Glistening against the awesome backdrop of the night sky above ESO_s Paranal Observatory, four laser beams project out into the darkness from Unit Telescope 4 UT4 of the VLT, a major asset of the Adaptive Optics system

    All of the light that’s emitted must pass through the strong magnetic field around the neutron star on its way to our eyes, telescopes, and detectors. If the magnetized space that it passes through exhibits the expected vacuum birefringence effect, that light should all be polarized, with a common direction of polarization for all the photons.

    In 2016, scientists were able to locate a neutron star that was close enough and possessed a strong enough magnetic field to make these observations possible. Working with the Very Large Telescope (VLT) in Chile, which can take fantastic optical and infrared observations, including polarization, a team led by Roberto Mignani was able to measure the polarization effect from the neutron star RX J1856.5–3754.

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    A contour plot of the phase-averaged linear polarization degree in two models (left and right): for an isotropic blackbody and for a model with a gaseous atmosphere. At top, you can see the observational data, while at the bottom, you can see what you get if you subtract out the theoretical effect of vacuum birefringence from the data. The effects match partically perfectly. (R.P. MIGNANI ET AL., MNRAS 465, 492 (2016))

    The authors were able to extract, from the data, a large effect: a polarization degree of around 15%. They also calculated what the theoretical effect from vacuum birefringence ought to be, and subtracted it out from the actual, measured data. What they found was spectacular: the theoretical effect of vacuum birefringence accounted for practically all of the observed polarization. In other words, the data and the predictions matched almost perfectly.

    You might think that a closer, younger pulsar (like the one in the Crab Nebula) might be better suited to making such a measurement, but there’s a reason that RX J1856.5–3754 is special: its surface is not obscured by a dense, plasma-filled magnetosphere.

    If you watch a pulsar like the one in the Crab Nebula, you can see the effects of opacity in the region surrounding it; it’s simply not transparent to the light we’d want to measure.

    Supernova remnant Crab nebula. NASA/ESA Hubble

    But the light around RX J1856.5–3754 is just perfect. With the polarization measurements in this portion of the electromagnetic spectrum from this pulsar, we have confirmation that light is, in fact, polarized in the same direction as the predictions arising from vacuum birefringence in quantum electrodynamics. This is the confirmation of an effect predicted so long ago — in 1936 — by Werner Heisenberg and Hans Euler that, decades after the death of both men, we can now add “theoretical astrophysicist” to each of their resumes.

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    The future X-ray observatory by the ESA, Athena, will include the capability of measuring the polarization of X-ray light from space, something that none of our leading observatories today, such as Chandra and XMM-Newton, can do. (ESA / ATHENA COLLABORATION)

    NASA/Chandra X-ray Telescope

    ESA/XMM Newton

    Now that the effect of vacuum birefringence has been observed — and by association, the physical impact of the virtual particles in the quantum vacuum — we can attempt to confirm it even further with more precise quantitative measurements. The way to do that is to measure RX J1856.5–3754 in the X-rays, and measuring the polarization of X-ray light.

    While we don’t have a space telescope capable of measuring X-ray polarization right now, one of them is in the works: the ESA’s Athena mission. Unlike the ~15% polarization observed by the VLT in the wavelengths it probes, X-rays should be fully polarized, displaying right around an 100% effect. Athena is currently slated for launch in 2028, and could deliver this confirmation for not just one but many neutron stars. It’s another victory for the unintuitive, but undeniably fascinating, quantum Universe.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 9:43 am on July 20, 2019 Permalink | Reply
    Tags: , , , , , NASA Frontier Development Lab,   

    From SETI Institute: “NASA Frontier Development Lab Returns to Silicon Valley to Solve New Challenges with AI” 

    SETI Logo new
    From SETI Institute

    Jun 24, 2019

    1

    Next week, NASA’s Frontier Development Lab, the SETI Institute, and FDL’s private sector and space agency partners will kick off its fourth annual summer research accelerator, applying the latest techniques in machine learning and artificial intelligence to address important science and exploration research challenges. This year, 24 early career Ph.Ds in AI and interdisciplinary natural science domains will be working in six interdisciplinary teams on challenge questions in the areas of space weather, lunar resources, Earth observation and astronaut health.

    “Since its inception, FDL has proven the efficacy of interdisciplinary research and the power of public-private partnership,” said Bill Diamond, president and CEO of the SETI Institute. “We are building on the extraordinary accomplishments of the researchers and mentors from the first three years and are excited to welcome another international group of amazing young scientists for this year’s program. We are also extremely grateful to all our private sector partners and especially to Google Cloud for their leadership role.”

    Partner organizations support FDL by providing funding, supplying hardware, AI/ML algorithms, datasets, software and cloud-compute resources. They also support working teams with mentors and subject matter experts and hosting key events, such as the first-week AI boot camp and the final public team presentations. This year, FDL is pleased to welcome back partners Google Cloud, Intel, IBM, KX, Lockheed Martin, Luxembourg Space Agency, and NVIDIA. We are also pleased to welcome our new partners Canadian Space Agency, HPE and Element AI.

    For the past three years, FDL has demonstrated the potential of applied AI to deliver important results to the space program in a very intense sprint, when supported in this way by a consortium of motivated partners. This approach has proven critical in unlocking meaningful progress in the complex and often systemic nature of AI problems.

    “NASA has been at the forefront of machine learning – e.g. robotics,” said Madhulika Guhathakurta, program scientist and heliophysicist on detail at NASA’s Ames Research Center in Silicon Valley. “But we’re now witnessing an inflection point, where AI promises to become a tool for discovery – where the ability to process vast amount of heterogeneous data, as well as massive amount of data collected over decades, allows us to revisit the physics-based models of the past – to better understand underlying principles and radically improve time to insight.”

    Each team is comprised of two Ph.D. or postdoc researchers from the space sciences and two data scientists, supported by mentors in each area. This year’s participants come from 13 countries and will be working on these challenges:

    Disaster prevention, progress and response (floods)
    Lunar resource mapping/super resolution
    Expanding the capabilities of NASA’s solar dynamics observatory
    Super-resolution maps of the solar magnetic field covering 40 years of space weather events
    Enhanced Predictability of GNSS Disturbances
    Generation of simulated biosensor data

    Additionally, three teams in Europe will be addressing disaster prevention, progress and response (floods), ground station pass scheduling and assessing the changing nature of atmospheric phenomena, in partnership with the European Space Agency (ESA).

    FDL 2019 kicks off next week at NVIDIA headquarters in Santa Clara, California, where teams will participate in a one-week intensive boot camp. The program concludes on August 15 at Google in Mountain View, California where teams will present the results of their work. Throughout the summer, teams will be working at the SETI Institute and NASA’s Ames Research Center near Mountain View.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    SETI Institute


    About the SETI Institute

    What is life? How does it begin? Are we alone? These are some of the questions we ask in our quest to learn about and share the wonders of the universe. At the SETI Institute we have a passion for discovery and for passing knowledge along as scientific ambassadors.

    The SETI Institute is a 501 (c)(3) nonprofit scientific research institute headquartered in Mountain View, California. We are a key research contractor to NASA and the National Science Foundation (NSF), and we collaborate with industry partners throughout Silicon Valley and beyond.

    Founded in 1984, the SETI Institute employs more than 130 scientists, educators, and administrative staff. Work at the SETI Institute is anchored by three centers: the Carl Sagan Center for the Study of Life in the Universe (research), the Center for Education and the Center for Outreach.

    The SETI Institute welcomes philanthropic support from individuals, private foundations, corporations and other groups to support our education and outreach initiatives, as well as unfunded scientific research and fieldwork.

    A Special Thank You to SETI Institute Partners and Collaborators
    • Campoalto, Chile, NASA Ames Research Center, NASA Headquarters, National Science Foundation, Aerojet Rocketdyne,SRI International

    Frontier Development Lab Partners
    • Breakthrough Prize Foundation, European Space Agency, Google Cloud, IBM, Intel, KBRwyle. Kx Lockheed Martin, NASA Ames Research Center, Nvidia, SpaceResources Luxembourg, XPrize

    In-kind Service Providers
    • Gunderson Dettmer – General legal services, Hello Pilgrim – Website Design and Development Steptoe & Johnson – IP legal services, Danielle Futselaar

    SETI/Allen Telescope Array situated at the Hat Creek Radio Observatory, 290 miles (470 km) northeast of San Francisco, California, USA, Altitude 986 m (3,235 ft)

    SETI Institute – 189 Bernardo Ave., Suite 100
    Mountain View, CA 94043
    Phone 650.961.6633 – Fax 650-961-7099
    Privacy PolicyQuestions and Comments

    Also in the hunt, but not a part of the SETI Institute


    SETI@home, a BOINC project originated in the Space Science Lab at UC Berkeley

    BOINCLarge

    BOINC is a leader in the field(s) of Distributed Computing, Grid Computing and Citizen Cyberscience.BOINC is more properly the Berkeley Open Infrastructure for Network Computing, developed at UC Berkeley.

     
  • richardmitnick 9:24 am on July 20, 2019 Permalink | Reply
    Tags: , , , Beyond the Galileo Experiment, , ,   

    From SETI Institute: “100 YEARS OF THE IAU: Beyond the Galileo Experiment” 

    SETI Logo new
    From SETI Institute

    Jul 5, 2019

    1

    Galileo’s closest approach to our planet in December 1990 allowed scientists to perform the first controlled experiment for the search for life on Earth from space.

    NASA/Galileo 1989-2003

    Ten months earlier, Voyager 1 had returned the iconic ‘Pale Blue Dot’ image.

    NASA/Voyager 1

    1
    The Pale Blue Dot” by Carl Sagan

    From beyond the orbit of Neptune, Earth appeared as a mere fraction of a pixel. The planetary portrait was captured at the suggestion of Carl Sagan, who was also the designer of the Galileo flyby experiment. The Pale Blue Dot became an instant symbol for a civilization stepping out of its planetary cradle in search of life beyond Earth. Success would require that humanity redefine itself from a cosmic perspective. Within 10 months of the Pale Blue Dot delivering the philosophical message, the Galileo experiment provided a scientific roadmap for the journey.

    In a commentary commissioned by Nature Astronomy for the 100th Anniversary of the IAU and published on July 5th, 2019, Dr. Nathalie A. Cabrol, astrobiologist and Director of the SETI Institute Carl Sagan Center for Research shows how, 26 years after its publication, A search for life on Earth from the Galileo spacecraft by Sagan et al. (1993) reveals a fused vision of a future of biosignature detection in the Solar System and beyond that is even more relevant today.

    You can read the full article at Nature:
    https://www.nature.com/articles/s41550-019-0839-3.epdf?author_access_token=WXdpWIIvGJeTn1khGF67RdRgN0jAjWel9jnR3ZoTv0M2090hjzd3iAY8Y_7pOmkQ5jAuZcceUL2M1XuY4rFPJyt9-TBcnJZ6XSIJC-WNDLxBjEGkpL8QTL3WuqNPMnZX3qjmxGEUwidwNtPSm9-6bQ%3D%3D

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    SETI Institute


    About the SETI Institute

    What is life? How does it begin? Are we alone? These are some of the questions we ask in our quest to learn about and share the wonders of the universe. At the SETI Institute we have a passion for discovery and for passing knowledge along as scientific ambassadors.

    The SETI Institute is a 501 (c)(3) nonprofit scientific research institute headquartered in Mountain View, California. We are a key research contractor to NASA and the National Science Foundation (NSF), and we collaborate with industry partners throughout Silicon Valley and beyond.

    Founded in 1984, the SETI Institute employs more than 130 scientists, educators, and administrative staff. Work at the SETI Institute is anchored by three centers: the Carl Sagan Center for the Study of Life in the Universe (research), the Center for Education and the Center for Outreach.

    The SETI Institute welcomes philanthropic support from individuals, private foundations, corporations and other groups to support our education and outreach initiatives, as well as unfunded scientific research and fieldwork.

    A Special Thank You to SETI Institute Partners and Collaborators
    • Campoalto, Chile, NASA Ames Research Center, NASA Headquarters, National Science Foundation, Aerojet Rocketdyne,SRI International

    Frontier Development Lab Partners
    • Breakthrough Prize Foundation, European Space Agency, Google Cloud, IBM, Intel, KBRwyle. Kx Lockheed Martin, NASA Ames Research Center, Nvidia, SpaceResources Luxembourg, XPrize

    In-kind Service Providers
    • Gunderson Dettmer – General legal services, Hello Pilgrim – Website Design and Development Steptoe & Johnson – IP legal services, Danielle Futselaar

    SETI/Allen Telescope Array situated at the Hat Creek Radio Observatory, 290 miles (470 km) northeast of San Francisco, California, USA, Altitude 986 m (3,235 ft)

    SETI Institute – 189 Bernardo Ave., Suite 100
    Mountain View, CA 94043
    Phone 650.961.6633 – Fax 650-961-7099
    Privacy PolicyQuestions and Comments

    Also in the hunt, but not a part of the SETI Institute


    SETI@home, a BOINC project originated in the Space Science Lab at UC Berkeley

    BOINCLarge

    BOINC is a leader in the field(s) of Distributed Computing, Grid Computing and Citizen Cyberscience.BOINC is more properly the Berkeley Open Infrastructure for Network Computing, developed at UC Berkeley.

     
  • richardmitnick 8:52 am on July 20, 2019 Permalink | Reply
    Tags: , , , , , ,   

    From SETI Institute : “Search for space aliens comes up empty, but extraterrestrial life could still be out there” 

    SETI Logo new
    From SETI Institute

    Jul 1, 2019
    Seth Shostak

    1
    Credit: Breakthrough Listen / Danielle Futselaar

    The “Breakthrough Listen” initiative listened in on 1,300 star systems and found no sign of E.T. But the search is set to expand.

    Breakthrough Listen Project

    1

    UC Observatories Lick Autmated Planet Finder, fully robotic 2.4-meter optical telescope at Lick Observatory, situated on the summit of Mount Hamilton, east of San Jose, California, 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


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

    Newly added-

    CfA/VERITAS, a major ground-based gamma-ray observatory with an array of four 12m optical reflectors for gamma-ray astronomy in the GeV – TeV energy range. Located at Fred Lawrence Whipple Observatory, Mount Hopkins, Arizona, US in AZ, USA, Altitude 2,606 m (8,550 ft)

    The search for extraterrestrial intelligence, or SETI, is a numbers game — and bigger numbers are better. The more places you look for alien beings — the more expansive your search — the greater the chance you’ll turn up proof of their existence. So it’s notable that Breakthrough Listen, a privately funded, decade-long research project based at the University of California, Berkeley, just announced a significant number of new observations. And while the researchers didn’t uncover any signals from extraterrestrials, they’ve taken a major step forward in the search.

    The basic premise of SETI — that we live in a galaxy festooned with brainy societies — rests upon the hypothesis that there must be many habitats in the Milky Way where complex biology has had a chance to evolve and thrive.

    Milky Way NASA/JPL-Caltech /ESO R. Hurt. The bar is visible in this image

    There are about a trillion planets in the Milky Way. If you represented each planet with a marble and laid them all out on the ground cheek by jowl, they’d cover an area larger than Washington, D.C. It doesn’t take an outsize imagination to expect that at least some fraction of this multitude are home to clever inhabitants.

    But how many is “some?” Even Nostradamus would struggle to come up with a precise answer. So let’s say one planet in a million, which doesn’t sound terribly brash (and we’re not even counting moons!). In that case, our galaxy has spawned roughly a million societies. Even if this estimate is hundreds or thousands of times too optimistic, there could still be plenty of aliens to find.

    But if this straw-man argument suggests that extraterrestrials are out there, it also suggests that detecting them will require a lot of searching. The new results from Breakthrough Listen — an examination of roughly 1,300 nearby stars — has approximately doubled the tally of reconnoitered real estate. This was not a trivial effort; it took scientists three years of heavy-duty work using large antennas in West Virginia and Australia. For each of these star systems, they carefully sifted through several billion radio channels, looking for a signal of the type that only a radio transmitter can produce.

    Frank Drake with his Drake Equation. Credit Frank Drake


    Drake Equation, Frank Drake, Seti Institute

    SETI/Allen Telescope Array situated at the Hat Creek Radio Observatory, 290 miles (470 km) northeast of San Francisco, California, USA, Altitude 986 m (3,235 ft)

    The bottom line of the new observations? No extraterrestrial radio emissions were detected. Sure, there were plenty of signals, but all could be ascribed to human activity — either transmitters here on Earth or orbiting satellites.

    If that surprises or disappoints you, get a grip. Those 1,300 stars represent only a minuscule sample of the total planetary population.

    It’s also worth noting that the new observations were reviewed only by the Breakthrough Listen team. Maybe they missed something. Others might apply their own signal-decoding algorithms and do their own analyses of this massive thicket of numbers and find something interesting. The Berkeley folks have made their data publicly accessible online just in case others want to try their personal favorite algorithm.

    Still, it’s clear that SETI so far has failed to come home with a kewpie doll. Neither Breakthrough Listen nor any other SETI project has picked up a compelling narrow-band radio signal — one that’s at a single spot on the radio dial — that clearly originates from a source beyond our solar system. But Breakthrough Listen at least has refined the equipment, developed the software and trained a half-dozen grad students, all with the intention of continuing and expanding the search.

    Indeed, the Breakthrough Listen team is thinking big. Their long-term goal is to target a million star systems — exceeding by hundreds of times the total number of targets scrutinized by SETI since the birth of the field 60 years ago.

    Examining a million stellar environments might sound impractical, but it’s not. While it took three years to add 1,300 to the list of observed systems, the speed of the search is increasing. It won’t take a century or two to add a million more. The actual timescale is closer to a decade. That should buoy readers who hope to be among the first humans to learn whether aliens really exist.

    Sure, there are no guarantees, and SETI rests upon a hypothesis that’s impossible to falsify. It may be that there is an abundance of inhabited worlds but that 21st century SETI technology — mostly listening for alien radio signals — is incapable of detecting them. But such caveats are no reason to stop trying, any more than we should abandon efforts to find a cure for the common cold just because none has yet been found.

    SETI has always butted up against the fact that the universe is very large and mostly empty — and that exploring large chunks of it takes a long time. But there’s both hope and expectation that, as the numbers grow, so too will the chance that one day we’ll find a scratchy signal — one that will change all future history.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    SETI Institute

    About the SETI Institute

    What is life? How does it begin? Are we alone? These are some of the questions we ask in our quest to learn about and share the wonders of the universe. At the SETI Institute we have a passion for discovery and for passing knowledge along as scientific ambassadors.

    The SETI Institute is a 501 (c)(3) nonprofit scientific research institute headquartered in Mountain View, California. We are a key research contractor to NASA and the National Science Foundation (NSF), and we collaborate with industry partners throughout Silicon Valley and beyond.

    Founded in 1984, the SETI Institute employs more than 130 scientists, educators, and administrative staff. Work at the SETI Institute is anchored by three centers: the Carl Sagan Center for the Study of Life in the Universe (research), the Center for Education and the Center for Outreach.

    The SETI Institute welcomes philanthropic support from individuals, private foundations, corporations and other groups to support our education and outreach initiatives, as well as unfunded scientific research and fieldwork.

    A Special Thank You to SETI Institute Partners and Collaborators
    • Campoalto, Chile, NASA Ames Research Center, NASA Headquarters, National Science Foundation, Aerojet Rocketdyne,SRI International

    Frontier Development Lab Partners
    • Breakthrough Prize Foundation, European Space Agency, Google Cloud, IBM, Intel, KBRwyle. Kx Lockheed Martin, NASA Ames Research Center, Nvidia, SpaceResources Luxembourg, XPrize

    In-kind Service Providers

    Gunderson Dettmer – General legal services
    Hello Pilgrim – Website Design and Development
    Steptoe & Johnson – IP legal services
    Danielle Futselaar

    SETI/Allen Telescope Array situated at the Hat Creek Radio Observatory, 290 miles (470 km) northeast of San Francisco, California, USA, Altitude 986 m (3,235 ft)

    SETI Institute – 189 Bernardo Ave., Suite 100
    Mountain View, CA 94043
    Phone 650.961.6633 – Fax 650-961-7099
    Privacy PolicyQuestions and Comments

    Also in the hunt, but not a part of the SETI Institute


    SETI@home, a BOINC project originated in the Space Science Lab at UC Berkeley

    BOINCLarge

    BOINC is a leader in the field(s) of Distributed Computing, Grid Computing and Citizen Cyberscience.BOINC is more properly the Berkeley Open Infrastructure for Network Computing, developed at UC Berkeley.

     
  • richardmitnick 1:37 pm on July 19, 2019 Permalink | Reply
    Tags: "Heating Up a Solar Flare", , , , ,   

    From AAS NOVA: “Heating Up a Solar Flare” 

    AASNOVA

    From AAS NOVA

    19 July 2019
    Kerry Hensley

    1
    NASA’s Solar Dynamics Observatory captures a solar flare in the act. [NASA/SDO]

    NASA/SDO

    Powerful solar flares are dazzlingly bright in ultraviolet and X-ray images of the Sun. Despite their demands for attention, there’s still a lot that we don’t know about these unpredictable eruptions.

    Clues from 121.6 nm

    2
    These Solar Dynamics Observatory images of the Sun show a solar flare in three extreme ultraviolet wavelengths. From left to right: 17.1, 30.4, and 13.1 nanometers. [NASA/GSFC/SDO]

    Solar flares shoot energetic particles and photons from across the electromagnetic spectrum into interplanetary space. In order to understand how energy is released in solar flares, we need to first know how energy is injected.

    To explore where flares get their energy, a team led by Jie Hong (Nanjing University, China) focused on a familiar feature of the ultraviolet solar spectrum: the 121.6-nm hydrogen Lyman-α emission line, produced by the roiling, turbulent hydrogen gas in the Sun’s atmosphere. The shape and behavior of the Lyman-α emission line can be used to learn about many different types of activity in the Sun’s chromosphere and corona — including solar flares.

    3
    Evolution of Lyman-α profiles over time. The top row shows the time evolution of the profiles in the non-thermal heating case. The asymmetry of the peaks transitions from long to short wavelengths as time and energy increase. The bottom row shows the thermal heating case (left) and the thermal heating plus a soft electron beam case (right). In the thermal heating case, the double peak morphs into a single peak.[Hong et al. 2019]

    Modeling Flare Emission

    Hong and collaborators used radiative hydrodynamics to model solar flares heated by different mechanisms. Their goal was to explore how the type of heating might change the shape of the Lyman-α line we observe.

    In particular, they examined two means of heating the flares: a thermal mechanism where the energy comes from conduction from nearby plasma, and a non-thermal mechanism where the heat is provided by a beam of energetic electrons generated by magnetic reconnection. In the non-thermal case, they also varied the strength of the heating by an order of magnitude.

    After allowing the modeled flares to evolve for eight or ten seconds, the researchers looked for subtle changes in the shape of the Lyman-α profile that could be linked to the underlying heating mechanism.

    The asymmetries and peaks of the modeled emission lines showed distinctive patterns and behavior over time — fingerprints, Hong and collaborators argue, that could help identify the source of heat for an observed flare.

    Flare Photography

    Hong and collaborators note that their modeling efforts will complement future solar observations, helping to clarify the complex picture of flare evolution.

    In particular, they look forward to the joint NASA-ESA Solar Orbiter mission, set to launch in 2020, which will be the first spacecraft to snap extreme-ultraviolet pictures of the Sun from out of the ecliptic plane, and China’s Advanced Space-Based Solar Observatory (ASO-S), which is scheduled for launch in 2022. ASO-S will carry a dedicated Lyman-α imager.

    ESA/NASA Solar Orbiter depiction

    4

    After decades of observations, it looks like the field of flare research is still heating up!

    Citation

    “The Response of the Lyα Line in Different Flare Heating Models,” Jie Hong et al 2019 ApJ 879 128.
    https://iopscience.iop.org/article/10.3847/1538-4357/ab262e

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

     
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