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  • richardmitnick 9:53 am on July 21, 2019 Permalink | Reply
    Tags: , , , Cecilia Payne, , COSMOS, , 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 1:12 pm on July 11, 2019 Permalink | Reply
    Tags: , Coral on the move to escape sea heat, COSMOS, , ,   

    From University of Washington and COSMOS: “Reefs on the move- Coral reefs shifting away from equator, new study finds” 

    U Washington

    From University of Washington

    AND

    Cosmos Magazine bloc

    From COSMOS Magazine

    July 9, 2019

    1
    Corals and kelp.Soyoka Muko/Nagasaki University

    Coral reefs are retreating from equatorial waters and establishing new reefs in more temperate regions, according to new research published July 4 in the journal Marine Ecology Progress Series. The researchers found that the number of young corals on tropical reefs has declined by 85% — and doubled on subtropical reefs — during the last four decades.

    “Climate change seems to be redistributing coral reefs, the same way it is shifting many other marine species,” said lead author Nichole Price, a senior research scientist at Bigelow Laboratory for Ocean Sciences in Maine. “The clarity in this trend is stunning, but we don’t yet know whether the new reefs can support the incredible diversity of tropical systems.”

    As climate change warms the ocean, subtropical environments are becoming more favorable for corals than the equatorial waters where they traditionally thrived. This is allowing drifting coral larvae to settle and grow in new regions. These subtropical reefs could provide refuge for other species challenged by climate change and new opportunities to protect these fledgling ecosystems.

    “This study is a great example of the importance of collaborating internationally to assess global trends associated with climate change and project future ecological interactions,” said co-author Jacqueline Padilla-Gamiño, an assistant professor at the University of Washington School of Aquatic and Fishery Sciences. “It also provides a nugget of hope for the resilience and survival of coral reefs.”

    The researchers believe that only certain types of coral are able to reach these new locations, based on how far the microscopic larvae can swim and drift on currents before they run out of their limited fat stores. The exact composition of most new reefs is currently unknown, due to the expense of collecting genetic and species diversity data.

    “We are seeing ecosystems transition to new blends of species that have never coexisted, and it’s not yet clear how long it takes for these systems to reach equilibrium,” said co-author Satoshi Mitarai, an associate professor at Okinawa Institute of Science and Technology Graduate University who earned his doctorate at the UW. “The lines are really starting to blur about what a native species is, and when ecosystems are functioning or falling apart.”

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    The study site on Palmyra Atoll, one of the Northern Line Islands that lies between Hawaii and American Samoa.
    Nichole Price/Bigelow Laboratory for Ocean Sciences

    This experiment in the Palmyra Atoll National Wildlife Refuge in the Pacific is allowing researchers to enumerate the number of baby corals settling on a reef.

    Recent studies show that corals are establishing new reefs in temperate regions as they retreat from increasingly warmer waters at the equator.

    Writing in the journal Marine Ecology Progress Series [above], researchers from 17 institutions in six countries report that the number of young corals has declined by 85% on tropical reefs during the last four decades, but -doubled on subtropical reefs.

    “Climate change seems to be redistributing coral reefs, the same way it is shifting many other marine species,” says lead author Nichole Price, from Bigelow Laboratory for Ocean Sciences, US.

    “The clarity in this trend is stunning, but we don’t yet know whether the new reefs can support the incredible diversity of tropical systems.”

    The research team has compiled a global database of studies dating back to 1974, when record-keeping began. They hope other scientists will add to it, making it increasingly comprehensive and useful to other research questions.

    See the full U Washington article here .
    See the full COSMOS article here .


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    The University of Washington is one of the world’s preeminent public universities. Our impact on individuals, on our region, and on the world is profound — whether we are launching young people into a boundless future or confronting the grand challenges of our time through undaunted research and scholarship. Ranked number 10 in the world in Shanghai Jiao Tong University rankings and educating more than 54,000 students annually, our students and faculty work together to turn ideas into impact and in the process transform lives and our world. For more about our impact on the world, every day.
    So what defines us —the students, faculty and community members at the University of Washington? Above all, it’s our belief in possibility and our unshakable optimism. It’s a connection to others, both near and far. It’s a hunger that pushes us to tackle challenges and pursue progress. It’s the conviction that together we can create a world of good. Join us on the journey.

     
  • richardmitnick 11:14 am on July 10, 2019 Permalink | Reply
    Tags: "Tamu Massif no longer our biggest volcano", And this all means that Mauna Loa on the island of Hawaii should once again be considered the world’s largest single volcano., “The largest volcano in the world is really the mid-ocean ridge system which stretches about 65000 kilometres around the world like stitches on a baseball", COSMOS,   

    From COSMOS Magazine: “Tamu Massif no longer our biggest volcano” 

    Cosmos Magazine bloc

    From COSMOS Magazine

    10 July 2019
    Nick Carne

    1
    Tamu Massif – no longer the biggest, but still impressive. University of Houston

    Tamu Massif was declared the largest single volcano in the world when it was located in the Pacific Ocean about 1600 kilometres east of Japan in 2013 – but now it seems it probably isn’t.

    And the leader of the team that found it is the first to agree.

    “The largest volcano in the world is really the mid-ocean ridge system, which stretches about 65,000 kilometres around the world, like stitches on a baseball,” says William Sager, a geophysicist at the University of Houston, US.

    “This is really a large volcanic system, not a single volcano.”

    In their original paper [Nature Geoscience], Sager and colleagues concluded that Tamu Massif was an enormous shield volcano, formed by far-reaching lava flows emanating from its summit.

    However, new findings by Sager and others, published in the journal Nature Geoscience, conclude that it is a different breed of volcanic mountain altogether.

    A research team from the US, China and Japan analysed magnetic field data over Tamu Massif, finding that magnetic anomalies – perturbations to the field caused by magnetic rocks in the Earth’s crust – resemble those formed at mid-ocean ridge plate boundaries.

    They compiled a magnetic anomaly map using 4.6 million magnetic field readings collected over 54 years along 72,000 kilometres of ship tracks, along with a new grid of magnetic profiles, positioned with modern GPS navigation.

    The map shows that linear magnetic anomalies around Tamu Massif blend into linear anomalies over the mountain itself, implying that the underwater volcano formed by extraordinary mid-ocean ridge crustal formation.

    The new findings also weaken the accepted analogy between eruptions of continental flood basalts and oceanic plateaus because the formation mechanisms are shown to be different, the researchers say.

    Sager is philosophical. “Science is a process and is always changing,” he says. “There were aspects of that explanation that bugged me, so I proposed a new cruise and went back to collect the new magnetic data set that led to this new result.

    “In science, we always have to question what we think we know and to check and double check our assumptions. In the end, it is about getting as close to the truth as possible – no matter where that leads.”

    And this all means that Mauna Loa, on the island of Hawaii, should once again be considered the world’s largest single volcano.

    4
    Mauna Loa Volcano, Hawaii, USA, towers nearly 3,000 m above the much smaller Kilauea Volcano (caldera in left center). Hualalai Volcano is in upper right. In recent years Mauna Loa has not erupted with the frequency of Kilauea, but its 33 historical eruptions have, on average, generated much larger volumes of lava on a daily basis — more than 10 times the lava output from Kilauea’s current Pu`u`O`o eruption. Lava flows on Mauna Loa tend to travel much longer distances in a shorter period of time than those on Kilauea. Thus, warnings and notifications in the first few hours of an eruption are critical for public safety.

    4
    OpenStreetMap – Map of Hawaii

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    Map showing relationship of Mauna Loa to other volcanoes that form the island of Hawai’i—the Big Island.

    See the full article here .


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  • richardmitnick 9:22 am on July 8, 2019 Permalink | Reply
    Tags: "Science history: Fritz Zwicky and the whole dark matter thing", , , , , COSMOS, Dark Matter science,   

    From COSMOS Magazine-“Science history: Fritz Zwicky and the whole dark matter thing” 

    Cosmos Magazine bloc

    From COSMOS Magazine

    08 July 2019
    Jeff Glorfeld

    He’s not a household name, but his influence was significant.

    Dark matter: sounds like a great name for a rock band, or maybe a sci-fi TV series. Of course, it’s both.

    It’s also one of the most intensely studied topics in the world of astronomy and physics.

    In April, Discover magazine published Corey S Powell’s “Out There” column with the headline “Dark matter is real. ‘Dark matter’ is a terrible name for it”, in which he says scientists “have been grappling with the mystery of dark matter for a long time, and I mean a looong time”.

    He says the history of dark-matter investigations “goes back at least to 1906”, when physicist Henri Poincare speculated about the amount of “matière obscure” in the Milky Way. Or to 1846 and the discovery of the planet Neptune, whose existence had been inferred by its gravitational pull well before it was actually observed.

    Our modern understanding of dark matter begins in the early 1930s with Swiss physicist Fritz Zwicky, called by Tom Ritchey, writing for the Swedish Morphological Society, “one of the broadest and most inventive scientists of his time”, and someone who “combined theoretical studies with eminently practical, humanitarian activities”.

    Fritz Zwicky discovered Dark Matter when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, did most of the work on Dark Matter.

    Fritz Zwicky from http:// palomarskies.blogspot.com

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    Fritz Zwicky at the 18-inch Schmidt telescope at Palomar Observatory in the 1930s.
    Caltech Optical Observatories

    Coma cluster via NASA/ESA Hubble

    Astronomer Vera Rubin at the Lowell Observatory in 1965, worked on Dark Matter (The Carnegie Institution for Science)


    Vera Rubin measuring spectra, worked on Dark Matter (Emilio Segre Visual Archives AIP SPL)


    Vera Rubin, with Department of Terrestrial Magnetism (DTM) image tube spectrograph attached to the Kitt Peak 84-inch telescope, 1970. https://home.dtm.ciw.edu

    Zwicky was born in Varna, Bulgaria, in 1898, the son of a Swiss merchant. At the age of six he was sent to Switzerland for schooling. In 1925 he moved to the US and went to work at the California Institute of Technology, in Pasadena.

    Zwicky and German-born astronomer Walter Baade used a revolutionary new telescope at the Mount Palomar mountain-top observatory in southern California to photograph large areas of the sky quickly, with little distortion, to map out hundreds of thousands of galaxies, now called the Zwicky Catalogue of Galaxies.

    They discovered that galaxies tended to cluster, “opening up a new chapter in the history of astronomy and cosmology”, Ritchey says.

    At the same time, Zwicky applied the “virial theorem” of gravitational potential energy to the Coma cluster of galaxies, which led him to propose evidence of unseen mass, so starting off the debate on what is now called dark matter.

    In his new book, Underland, Robert Macfarlane says Zwicky observed that the galaxies “were revolving much faster than expected, especially towards the outer reaches of the cluster. At such speeds, individual galaxies should have broken their gravitational hold on one another, dispersing the cluster.

    “There was, Zwicky determined, only one possible explanation. There had to be another source of gravity, powerful enough to hold the cluster together given the speeds of revolution of the observable bodies. But what could supply such huge gravitational field strength, sufficient to tether whole galaxies – and why could he not see this ‘missing mass’?

    “Zwicky found no answers to his questions , but in asking them he began a hunt that continues today. His ‘missing mass’ is now known as ‘dark matter’ – and proving its existence and determining its properties is one of the grail-quests of modern physics.”

    Zwicky and Baade also observed “bright novae” in order to determine the distance to galaxies, coining the term “supernova”, which Zwicky proposed marked the transition from ordinary stars to neutron stars – which he was the first to hypothesise – and were the origin of cosmic rays.

    “This was an amazing (and correct) triple hypothesis and was an important step in the still on-going project to determine the size and age of the (visible) universe,” says Ritchey.

    See the full article here .


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  • richardmitnick 10:16 am on July 6, 2019 Permalink | Reply
    Tags: , , Australian Square Kilometre Array Pathfinder (ASKAP), , Caltech Owens Valley Long Wavelength Array, , COSMOS, , FRBs are surprisingly common with perhaps 2000 of them pinpricking the sky every day, One of the big issues in astrophysics he adds is that most of the matter in the universe is invisible to us., , The vast majority are one-off events   

    From COSMOS Magazine: “A decade waiting (and working), then two FRBs nailed in a week” 

    Cosmos Magazine bloc

    From COSMOS Magazine

    06 July 2019
    Richard A Lovett

    But Australian and US astronomers took different approaches.

    1
    An artist’s impression of Australia’s ASKAP radio telescope observing fast radio bursts.
    OZGRAV, SWINBURNE UNIVERSITY OF TECHNOLOGY.

    In less than a week as June became July, two teams of radio astronomers – one in Australia, the other in the US – announced they had independently accomplished a decade-long astronomical quest: identifying the sources of powerful blasts of intergalactic radiation known as fast radio bursts (FRBs).

    FRBs are enormous blazes of radio energy that in a few milliseconds can broadcast as much energy in radio waves as the monthly output of the sun in all forms combined.

    What causes them is unknown, but it can only be something dramatic, such as a collision between neutron stars, or even a neutron stars falling into a black hole. “For a long time, there were more theories than [known] bursts,” says Keith Bannister, an astronomer with CSIRO’s Australia Telescope National Facility (ATNF) and leader of the Australian team.

    FRBs are surprisingly common, with perhaps 2000 of them pinpricking the sky every day, Bannister says, but only a tiny fraction are detectable, “because traditional radio telescopes only see a small fraction of the sky”.

    Also, the vast majority are one-off events, making it incredibly difficult to figure out what galaxy they are coming from, once they are spotted.

    In an effort to solve this problem, Bannister’s team equipped 36 identical 12-metre radio telescopes that together form the Australian Square Kilometre Array Pathfinder (ASKAP) in Western Australia with a “phased array feed” that allowed each dish to see 36 distinct patches of the sky at once, each about 200 times larger than the full moon.

    They also upgraded their software to rapidly triangulate on an FRB via 0.1 nanosecond differences in the time it takes the signal to reach the various telescopes in the array: a method, Bannister says, that allowed them to pinpoint its origin to a precision of 1/50,000th of a degree – the width of a human hair, 200 metres away.

    The US team took a different approach. Rather than retrofitting an existing telescope array, it built a new one from the ground up.

    Due to the extreme brightness of FRBs, “Keith Bannister and I both realised that we can utilise relatively insensitive but wide field-of view telescopes to try to localise them,” says its leader, Vikram Ravi, a radio astronomer at California Institute of Technology, Pasadena.

    His team therefore purchased 10 broad-field-of-view 4.5-meter radio antennas – instruments not much larger than the best satellite TV dishes – and laid them out in the Owens Valley of eastern California, at a total cost of under $US500,000.

    Caltech Owens Valley Long Wavelength Array-currently hosts LEDA, the largest correlator ever built, Owens Valley, California, Altitude 1,222 m (4,009 ft)

    “It was a shoestring experiment,” Ravi says. “I literally moved them in place and focused them by hand.” The ultimate goal, he adds, is to expand the project to include 110 such dishes.

    Finding the sources of FRBs is important for two reasons. One is simply that it helps us figure out what causes them. The FRB located by Bannister’s team, for example, came not from the centre of its galaxy, but from its outskirts – “or at least its suburbs”, Bannister says. “This means our FRB wasn’t produced by a gigantic black hole at the galaxy’s centre.”

    Ravi adds that both the FRBs come from mature, Milky Way style galaxies. That’s interesting because the only other FRB whose source has ever been identified – a repeating burster whose repeated bursts made it easier to localise – came from a very different type of galaxy. That one had 1000 times less mass but was in a “starburst” stage, in which it was forming new stars at an extremely rapid pace.

    Based on that, one theory had been that FRBs came from the deaths of such galaxies’ most giant youthful stars, which live fast and die in blazes of glory known as superluminous supernovae.

    But such gigantic explosions are uncommon in more mature galaxies, suggesting that in the case of the two FRBs identified by Bannister’s team and Ravi’s, superluminous supernovae probably didn’t play a role.

    Localising the sources of FRBs is also important, Ravi says, because FRBs can be used as probes of the distribution of matter in the universe.

    One of the big issues in astrophysics, he adds, is that most of the matter in the universe is invisible to us.

    Much of that is dark matter, an enigmatic substance to date is detected only by its gravity, but the vast bulk of normal matter is also invisible, Ravi says. All that’s known is that it’s very hot – on the order of a million degrees or more – and very diffuse, partly contained in tenuous halos around galaxies, but possibly also dispersed throughout the intergalactic medium.

    FRBs, Ravi says, offer a way to figure out where this unseen matter lies, and how it is distributed.

    That’s because as the radio burst travels through this diffuse medium, different frequencies travel at slightly different speeds. It’s not a big difference, but it’s enough that an FRB signal can become stretched as it travels, with higher frequencies travelling faster, and lower frequencies travelling slower.

    “We observe the burst arriving first at the high frequencies, then later at the low frequencies,” Ravi says, an effect that can stretch a millisecond FRB to nearly a second.

    Different parts of the signal can also reach us by different paths, in which they start out travelling in a slightly different direction than the main part of the signal, then are refracted back into our own line of sight.

    “It’s sort of like why stars twinkle,” Ravi says.

    The effect is small, but it’s a sign that the medium through which the FRB signal propagated might have been “clumpy”, rather than uniformly distributed.

    To figure all of this out, Ravi says, it’s really useful to know how far an FRB signal has been travelling before it reaches us (and to know how many other galaxies it has passed close to. That’s another reason why it’s useful to locate the source galaxies of as many such signals as possible.

    Shami Chatterjee, a radio astronomer at Cornell University, Ithaca, New York, and leader of the team that located the source of the repeating FRB, agrees.

    Bannister’s find (and by extension, Ravi’s), he says, is “a magnificent technical achievement” that should, among other things, open the floodgates to more such findings, allowing FRBs to live up to their promise as probes of the intergalactic medium.

    “Once we have a few dozen,” he says, “FRBs will be one of the only viable probes of the intergalactic medium.”

    See the full article here .


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  • richardmitnick 9:45 am on July 6, 2019 Permalink | Reply
    Tags: , , , , COSMOS, , , , Neutron star collisions   

    From COSMOS Magazine: “We are stardust. And Big Bang dust.” 

    Cosmos Magazine bloc

    From COSMOS Magazine

    06 July 2019
    Katie Mack

    Neutron star collisions appear to be essential to our chemical origin story.

    1
    Artist’s now iconic conception shows two merging black holes similar to those detected by LIGO in 2017.
    LIGO/Caltech/MIT/Sonoma State (Aurore Simonnet)

    When, in 2017, the LIGO experiment detected gravitational waves from two neutron stars colliding, it sent electromagnetic and gravitational ripples through the universe and the astronomical community.

    This remarkable event, hotly anticipated but never before seen in this way, did more than give us a few new data points about the deaths of stars – it fundamentally changed our understanding of where we and our constituent atoms come from.

    You may have heard before that “we are stardust”. This isn’t wrong. But it’s not the whole story, either.

    A star is, fundamentally, an alchemy machine. It starts as a giant ball of mostly hydrogen gas, slowly crushing its central regions with the pressure of its own gravity. The core of a star eventually gets so hot and dense that it becomes a nuclear reactor, fusing hydrogen into helium.

    In the core of our own sun, this process is converting hundreds of millions of tons of hydrogen into helium every second; what we receive as sunlight is essentially just the waste heat from the reaction.

    This is how the vast majority of stars spend their lives: steadily burning themselves up, turning hydrogen into helium for billions of years. In their final death throes, as they become red giants ready to expel their outer layers, the fusion flares up in bursts, making lithium, carbon and nitrogen, and a smattering of heavier elements.

    To fill in the rest of the periodic table, though, we need stars much more massive than our own. A star more than about eight times as massive as the sun contains at its centre a nuclear furnace that’s burning unimaginably hot.

    After it tears through its supply of hydrogen in the core, it climbs up the list of elements, burning helium, carbon, neon, oxygen and silicon, until after only a few million years the centre of the star is iron and the fusion radiation that had been puffing the star up finally runs out.

    At that point, nothing can stop the star from collapsing on itself, resulting in a spectacular supernova explosion. In the end, at the centre of the debris field will be either a super-dense neutron star or a black hole.

    It’s this final explosion itself, rather than the interior burning, that creates the star’s ultimate chemical legacy. For a brief moment, a shock wave explodes through the layers of the star, creating heat and pressure so intense that a blast front of nuclear fusion carries a radioactive shell of new elements out into interstellar space.

    The universe is seeded with stardust, ready to coalesce into new stars, new planets, new life. For years, it was thought that these stellar deaths were the main mechanisms by which the universe was enriched with metals and other heavy elements.

    But evidence has been mounting that for heavy metals like gold, platinum and uranium, the supernova is just the beginning. It’s the tiny, dense, neutron star that carries within it the potential to explode across the rest of the periodic table.

    Which brings us back to the LIGO detection. When the signal was first seen, astronomers around the world trained their telescopes on the same part of the sky. The resulting observations showed a clear sign in the brief flash that the stars had created enough gold to outweigh the Earth several times over.

    2

    https://reports.news.ucsc.edu/neutron-star-merger/
    Please access this huge project on the 2017 find
    Credits

    Writing:
    Tim Stephens
    Video:
    Nick Gonzales
    Photos:
    Carolyn Lagattuta
    Header image:
    Illustration by Robin Dienel courtesy of the Carnegie Institution for Science
    Design and development:
    Rob Knight
    Project managers:
    Sherry Main, Scott Hernandez-Jason, Tim Stephens

    Neutron star collisions appear to be essential to our chemical origin story. We are born of unimaginable violence in the stellar generations that came before our own. But there’s more to the story.

    Most of the atoms in our bodies didn’t come from stars at all. They are, in fact, much more ancient. If you count up all the atoms in your body, more than 60% will be hydrogen, and the majority of the hydrogen in the universe has never been in a star at all.

    Hydrogen, or, specifically, the protons that would later join with electrons to make neutral hydrogen atoms, was created in the primordial fire of the Big Bang itself.

    In the first moments of the universe, every part of space was filled with a kind of prenuclear plasma hotter and denser than the centre of even the most massive star.

    As this fire expanded and cooled, protons and neutrons, the building blocks of atomic nuclei, first came into being.

    Hydrogen appeared in the form of solitary protons, along with small amounts of helium and lithium. These nuclei have persisted for the 13.8 billion years since those first moments, coming together in stars and, eventually, us.

    So, yes, you are stardust. But you are also the ashes of the Big Bang: ancient atomic alchemy brought together by the inexorable flow of gravity and time.

    See the full article here .


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  • richardmitnick 1:06 pm on June 30, 2019 Permalink | Reply
    Tags: , COSMOS, , ,   

    From COSMOS Magazine: “Thanks to AI, we know we can teleport qubits in the real world” 

    Cosmos Magazine bloc

    From COSMOS Magazine

    26 June 2019
    Gabriella Bernardi

    Deep learning shows its worth in the word of quantum computing.

    1
    We’re coming to terms with quantum computing, (qu)bit by (qu)bit.
    MEHAU KULYK/GETTY IMAGES

    Italian researchers have shown that it is possible to teleport a quantum bit (or qubit) in what might be called a real-world situation.

    And they did it by letting artificial intelligence do much of the thinking.

    The phenomenon of qubit transfer is not new, but this work, which was led by Enrico Prati of the Institute of Photonics and Nanotechnologies in Milan, is the first to do it in a situation where the system deviates from ideal conditions.

    Moreover, it is the first time that a class of machine-learning algorithms known as deep reinforcement learning has been applied to a quantum computing problem.

    The findings are published in a paper in the journal Communications Physics.

    One of the basic problems in quantum computing is finding a fast and reliable method to move the qubit – the basic piece of quantum information – in the machine. This piece of information is coded by a single electron that has to be moved between two positions without passing through any of the space in between.

    In the so-called “adiabatic”, or thermodynamic, quantum computing approach, this can be achieved by applying a specific sequence of laser pulses to a chain of an odd number of quantum dots – identical sites in which the electron can be placed.

    It is a purely quantum process and a solution to the problem was invented by Nikolay Vitanov of the Helsinki Institute of Physics in 1999. Given its nature, rather distant from the intuition of common sense, this solution is called a “counterintuitive” sequence.

    However, the method applies only in ideal conditions, when the electron state suffers no disturbances or perturbations.

    Thus, Prati and colleagues Riccardo Porotti and Dario Tamaschelli of the University of Milan and Marcello Restelli of the Milan Polytechnic, took a different approach.

    “We decided to test the deep learning’s artificial intelligence, which has already been much talked about for having defeated the world champion at the game Go, and for more serious applications such as the recognition of breast cancer, applying it to the field of quantum computers,” Prati says.

    Deep learning techniques are based on artificial neural networks arranged in different layers, each of which calculates the values for the next one so that the information is processed more and more completely.

    Usually, a set of known answers to the problem is used to “train” the network, but when these are not known, another technique called “reinforcement learning” can be used.

    In this approach two neural networks are used: an “actor” has the task of finding new solutions, and a “critic” must assess the quality of these solution. Provided a reliable way to judge the respective results can be given by the researchers, these two networks can examine the problem independently.

    The researchers, then, set up this artificial intelligence method, assigning it the task of discovering alone how to control the qubit.

    “So, we let artificial intelligence find its own solution, without giving it preconceptions or examples,” Prati says. “It found another solution that is faster than the original one, and furthermore it adapts when there are disturbances.”

    In other words, he adds, artificial intelligence “has understood the phenomenon and generalised the result better than us”.

    “It is as if artificial intelligence was able to discover by itself how to teleport qubits regardless of the disturbance in place, even in cases where we do not already have any solution,” he explains.

    “With this work we have shown that the design and control of quantum computers can benefit from the using of artificial intelligence.”

    See the full article here .


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    Please help promote STEM in your local schools.

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  • richardmitnick 11:12 am on June 27, 2019 Permalink | Reply
    Tags: "Planets in multiple-star systems may be habitable", , , , , COSMOS, U Texas Arlington   

    From U Texas Arlington via COSMOS: “Planets in multiple-star systems may be habitable” 

    1

    From U Texas Arlington

    via

    27 June 2019
    Richard A Lovett

    But don’t expect life to be easy, or even stable.

    1
    Planets in multiple-star systems may be habitable. But just how habitable? Stocktrek Images via Getty Images

    In a finding that’s great news for fans of Luke Skywalker’s fictional home planet Tatooine, scientists say planets in multiple-star systems may be habitable – though in keeping with Tatooine’s hardscrabble image, it may be an uphill battle.

    Astronomers have long known that multiple-star systems are common. “Most stars are members of binaries [other than the coolest dwarf stars],” Manfred Cuntz, an astrophysicist at the University of Texas at Arlington, said at this this week’s at AbSciCon 19 conference in Bellevue, Washington, US.

    And, astronomers are learning, many of these binary-star systems have planets – some circling a single star, and some circling both at once.

    Life on these planets could have a hard go of it, however.

    Partly that’s because multiple stars can perturb a planet’s orbit, precluding any chance for life as we know it to survive. But even for planets in stable orbits, these stars can produce habitable zones that change dramatically as the stars move around each other.

    The habitable zone is the region in a planetary system where an earthlike world would receive enough stellar energy for liquid water to exist on its surface. Being in the habitable zone isn’t the only requirement for a world to be habitable, but it’s long been considered an important starting point.

    With single-star systems like ours, it’s a simple concept, defined by the brightness of the star and how far you are from it.

    But on Tatooine-like worlds, the habitable zone varies as the stars move around each other, changing their distances from the planet and thereby changing the amount of stellar energy it receives – an effect that can be particularly pronounced if the two stars aren’t of the same brightness.

    The result, says Siegfried Eggl of the University of Washington, Seattle, is a significant restriction in the range of orbits that can allow planets to remain in the habitable zone – never too hot and never too cold – regardless of the changing positions of their stars.

    That said, a planet in a double-star system might still be habitable even it occasionally finds itself outside of the habitable zone, so long as it doesn’t stay there too long.

    How much time a planet can tolerate outside of the habitable zone depends on how quickly its atmosphere reacts to changes in incoming sunlight, Eggl says.

    If the atmosphere is thin, the planet’s climate will react quickly to such excursions, and it won’t be able to tolerate long ones. But if its “climate inertia” is large, it might be able to tolerate longer excursions into regions of too much or too little heat, so long as it gets the right amount of energy, on average.

    But that’s not the only problem Tatooine-like worlds must deal with. They can also see dramatic changes in their seasonal cycles, with the differences between summer and winter sometimes being moderate, and sometimes extreme.

    The problem stems from the planet’s tilt, technically called its obliquity.

    On Earth, this is 23½ degrees, and gives rise to our seasons, as our planet turns first one hemisphere, then the other toward the Sun.

    But the force of other objects’ gravities can cause this obliquity to change. On Earth, this change is limited to a 2.4-degree range, but that’s enough for the changes to be linked to such major climate changes as ice ages.

    In binary star systems, this effect can be radically stronger, says Billy Quarles of Georgia Institute of Technology, Atlanta, Georgia, especially if the planet’s orbit doesn’t lie in the same plane as its stars’ orbits around each other.

    “Seasons around these binaries may be a lot more variable than on Earth,” he says. “There are times when there are no seasons, and others when seasons [are larger], on a time scale of a few tens of thousands of years.”

    But that doesn’t mean everything about binary star systems reduces their planets’ habitability.

    Paul Mason, an astrophysicist at New Mexico State University, Las Cruces, New Mexico, argues that there is a “binary habitability mechanism” that can sometimes enhance a planet’s chances of being habitable.

    It works, Mason says, by reducing the risk of hyper-intense solar flares.

    On our own planet, these create dramatic northern and southern lights, bombard astronauts and satellites in dangerous amounts of radiation, disrupt communications, and pose risks to electronics and power grids.

    But many stars, especially in their youths have enormous flares that are risks not just to technology, but to life itself. These gigantic flares can erode a young planet’s atmosphere, blast its water vapor off into space, and kill a potentially habitable world in its youth.

    The strength and frequency of these flares, however, is dependent on the star’s rotation rate: the faster it spins the more flares it produces.

    Young stars spin quickly, slowing down as they age. But in binary star systems, tidal forces between the stars can put the brakes on their spins, rapidly taming their youthful activity. The result, Mason says, is that in some circumstances, “conditions for life are enhanced.”

    Conditions around these stars, he says, could therefore be “better than earth-like” – at least compared to what Earth experienced in its first billion years. “The Earth suffered a lot of water [and] atmosphere loss,” he says.

    In fact, he says, whatever other issues they pose, binary star systems could actually provide the best niches for life in the galaxy.

    Luke Skywalker would undoubtedly agree.

     
  • richardmitnick 10:45 am on June 17, 2019 Permalink | Reply
    Tags: , , “There is a quasar in the Milky Way’s future”, , , COSMOS, Feeding black holes produce large amounts of X-rays, Giant black holes form when two galaxies each with black holes at its own heart collide, Nobody before had ever caught one in the act of making the transition from red to blue, , Red quasars are common as are blue ones   

    From COSMOS Magazine: “New class of quasars offers clue to fate of our galaxy” 

    Cosmos Magazine bloc

    From COSMOS Magazine

    17 June 2019
    Richard A Lovett

    Astronomers looking for the blue ones make an important discovery.

    1
    The Milky Way, as seen from Lake Tekapo, New Zealand. There is a quasar in its future, astronomers now believe. ARUTTHAPHON POOLSAWASD / Getty Images

    Astronomers peering back in time by studying galaxies so far away that their light has been travelling for more than half the age of the universe have discovered a new class of quasar – and a clue to the ultimate fate of our own galaxy.

    Quasars are the most luminous objects in the universe, emitting as much energy as 10 trillion suns, says Allison Kirkpatrick, an astronomer at the University of Kansas, Lawrence, US, and are associated with gigantic black holes at the heart of the largest galaxies.

    “I am a black-hole hunter, and quasars are the most massive of these,” she said at a meeting of the American Astronomical Society in St. Louis, Missouri.

    Such giant black holes form when two galaxies, each with black holes at its own heart, collide.

    At that point, several things happen.

    First, the collision stirs up the gas and dust in these galaxies, pushing it toward their centres. Then, the gas and dust start to fall into the black holes, now in the process of merging.

    “They begin to feed rapidly on the gas around them,” Kirkpatrick says. “This is the quasar stage. They are almost universally produced by major mergers.”

    Feeding black holes produce large amounts of X-rays, but initially, these X-rays are blocked by the gas and dust clouds that have been drawn into the merging galaxies’ centre.

    “It obscures the X-rays,” says Kirkpatrick says – but the heated gas and dust isn’t invisible. Instead of X-rays, it emits vast amounts of infrared light that can be detected by earthly astronomers.

    “We have a dust-reddened quasar,” she says, “[with] very massive black-hole activity going on, but hidden from view.”

    Then, things shift. The powerful radiation being emitted by the quasar overcomes the gravity drawing dust and gas inward toward it, and rapidly blows dust and gas entirely out of the galaxy. “Now we see a luminous blue quasar,” she says.

    But nobody before had ever caught one in the act of making the transition, where the gas and dust have been blown out of the inner part of the galaxy, but not yet out of its outer reaches.

    To find one, Kirkpatrick’s team examined the 1600 most active known quasars, looking for ones that were blue – indicating that their cores had been swept sufficiently free of gas and dust for us to see the quasar itself – but which also emitted a lot of infrared light, indicating that their outer reaches still contained rings of hot gas and dust.

    And, while such objects were rare, Kirkpatrick’s team found 22 of them, all six to 12 billion light years away, including a galaxy that had both a blue quasar and 100 times more dust than our own Milky Way.

    That said, it’s a transition phase. “This new population of quasars are rare and short-lived, she says.

    They also mark the beginning of these galaxies’ deaths, because without their gas and dust, they can no longer form new stars. “We believe that it is the massive black hole that kills them,” Kirkpatrick says.

    And while her study was peering six billion to 12 billion years back in time, it also predicts the future our own Milky Way. “There is a quasar in the Milky Way’s future,” she says.

    That’s because our galaxy will eventually collide with the Andromeda galaxy, a galaxy about the size of our own, currently about 2.5 million light years away.

    Both galaxies have giant black holes at their centres. Neither black hole is currently doing anything dangerous, but when they collide, Kirkpatrick says, both will light up dramatically.

    “That will dominate our night sky,” she says. “They will be incredibly bright. The nice plane of the Milky Way will be dominated by this bright halo [marking the location of the merging black holes].”

    Then, all the gas and dust will be blown out of the merged galaxies and star and planet formation will be shut off. Existing planets will probably survive, Kirkpatrick says, “but you won’t get anything new. They’ll just be going around red dwarfs until eventually [their stars] burn out”.

    Not that this is anything of immediate concern to humans. The merger won’t occur for another three to four billion years, Kirkpatrick says. “That will be about the same time the sun has turned into a red giant, so we will have other problems to occupy us at the time.”

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

     
  • richardmitnick 12:09 pm on May 22, 2019 Permalink | Reply
    Tags: "Silicon surges as quantum tech favourite", COSMOS,   

    From UNSW via COSMOS Magazine: “Silicon surges as quantum tech favourite” 

    U NSW bloc

    From University of New South Wales

    via

    Cosmos Magazine bloc

    COSMOS Magazine

    22 May 2019
    Alan Duffy

    1
    Beads made of silicon balanced on the head of a pin. Once thought to be useful only in traditional computing, the element is enjoying a new lease of life in quantum research. Credit: Texas Instruments/Getty Images

    Three breakthrough papers published in just the past year have confirmed that silicon is neck-and-neck with competing technology for quantum computing, including those under active research by corporate giants Google, Microsoft and IBM.

    Creating the quantum entangled pairs that form the qubits, the heart of quantum computation, has thus far required the use of complex, exotic materials and structures, such as from honeycomb boron nitride and trapping molecules in lasers.

    Although these techniques are incredibly promising they have one significant downside – throwing away the trillions of dollars and decades of research and development invested in the traditional computing material, silicon.

    Now an Australian team led by Andrew Dzurak from the University of New South Wales (UNSW) has made a series of breakthroughs that have suddenly made silicon a leading focus for materials research quantum computer development.

    Qubits hold great promise, but unlike bits in traditional computing, they are error prone. This means millions are required for complex calculations to allow for error correction.

    Using existing techniques for forming quantum entangled pairs, any potential quantum computer would be unfeasibly large. That’s why three recent papers by the UNSW researchers are so important.

    The first, published in the journal Nature Electronics, showed silicon reaching an accuracy (or fidelity) for one-qubit logic of 99.96%.

    “This puts it on an even par with all other competing qubit technologies”, explains Dzurak, “since all qubits have errors, and these must be kept very low if we want to do useful computations, otherwise the final answers to calculations will be unreliable.”

    The result was followed up by a second paper, in the journal Nature, which demonstrated that two-qubit computations had reached 98% accuracy, an important step because linking qubits together is how quantum computations are undertaken.

    “We think that we’ll achieve significantly higher fidelities in the near future, opening the path to full-scale, fault-tolerant quantum computation,” says Dzurak.

    “We’re now on the verge of a two-qubit accuracy that’s high enough for quantum error correction.”

    These two sets of findings are key to constructing more feasible quantum computers, because greater accuracy means fewer redundant qubits are required for error correction.

    A third paper, just published in the journal Nature Nanotechnology, took the team’s work to an all-new practical level.

    “It shows it is possible to read out the state of a quantum bit in a silicon device using only a single wire (in this case a nanoscale electrode), vastly simplifying the on-chip electronics needed for a full-scale quantum processor chip,” explains Dzurak.

    The fewer qubits required for processing problems, combined with reducing the size of read-outs required for each qubit enough, dramatically reduces the size and complexity of a quantum computer, thus bringing it that much closer to reality.

    And industry has taken note.

    The advances have made possible the scaling up of a system using silicon, based on industry-standard complementary metal-oxide-semiconductor (CMOS) transistors, in a joint venture between UNSW, Australian company Silicon Quantum Computing (SQC) and the CMOS chip manufacturing capabilities at the French technology agency CEA.

    In using silicon for the quantum computing revolution, Australian researchers have shown that an old element can be taught new tricks.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    U NSW Campus

    Welcome to UNSW Australia (The University of New South Wales), one of Australia’s leading research and teaching universities. At UNSW, we take pride in the broad range and high quality of our teaching programs. Our teaching gains strength and currency from our research activities, strong industry links and our international nature; UNSW has a strong regional and global engagement.

    In developing new ideas and promoting lasting knowledge we are creating an academic environment where outstanding students and scholars from around the world can be inspired to excel in their programs of study and research. Partnerships with both local and global communities allow UNSW to share knowledge, debate and research outcomes. UNSW’s public events include concert performances, open days and public forums on issues such as the environment, healthcare and global politics. We encourage you to explore the UNSW website so you can find out more about what we do.

     
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