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  • richardmitnick 3:13 pm on January 26, 2022 Permalink | Reply
    Tags: "International research network welcomes new partners", BRIdge the Disciplines related to the Galactic Chemical Evolution-or BRIDGCE, Chemical Elements as Tracers of the Evolution of the Cosmos- Infrastructures for Nuclear Astrophysics-ChETEC-INFRA, , LIGO and Virgo, Michigan State University-led International Research Network for Nuclear Astrophysics expands to include three new partners in global quest to answer science’s most important questions., , The Canadian Nuclear Physics for Astrophysics Network-or CaNPAN,   

    From The Michigan State University (US): “International research network welcomes new partners” 

    Michigan State Bloc

    From The Michigan State University (US)

    Jan. 20, 2022
    Karen King

    1
    The Michigan State University-led International Research Network for Nuclear Astrophysics has expanded to include three new partners in its global quest to answer science’s most important questions.
    Credit: FRIB at The Michigan State University (US)

    Michigan State University-led International Research Network for Nuclear Astrophysics expands to include three new partners in global quest to answer science’s most important questions.

    Science is a team sport. Searching for answers to science’s fundamental questions requires not only team effort, but the effort of multiple teams across multiple countries.

    In its quest to answer questions about the evolution and properties of cosmic matter and the origin of the world’s chemical elements, the International Research Network for Nuclear Astrophysics, or IReNA, supported by the National Science Foundation (US) and headquartered at Michigan State University, is expanding to include three new crucial research partners.

    IReNA’s new member networks are:

    BRIdge the Disciplines related to the Galactic Chemical Evolution-or BRIDGCE, is a United Kingdom-wide network supported by the Science and Technology Facilities Council, part of UK Research and Innovation. The goal of this network is to facilitate connections across the different disciplines involved in the study of the origin of the elements and using chemical elements as tracers of the universe’s evolution.

    The Canadian Nuclear Physics for Astrophysics Network-or CaNPAN, in Canada is a collaboration of astrophysicists and nuclear physicists. Its goal is to use Canadian nuclear physics facilities, expertise and equipment — in conjunction with Canadian computing resources — to provide education and advances in the understanding of the creation of the chemical elements and the role of stars in the universe.

    Chemical Elements as Tracers of the Evolution of the Cosmos- Infrastructures for Nuclear Astrophysics-ChETEC-INFRA, in Europe has partner institutions in 17 countries. It provides them access to the infrastructures necessary for nuclear astrophysics research: astronuclear laboratories, supercomputers and telescopes.

    They join six other networks that comprise IReNA: Joint Institute for Nuclear Astrophysics – Center for the Evolution of the Elements, or JINA-CEE; Chemical Elements as Tracers of the Evolution of the Cosmos, or ChETEC; ExtreMe Matter Institute, or EMMI; Nucleosynthesis Grid collaboration, or NuGRID; Collaborative Research Center “The Milky Way System,” or SFB 881; and Japan Forum of Nuclear Astrophysics/UKAKUREN.

    “We are very excited about the ‘bridge over the Atlantic Ocean’ joining the UK BRIDGCE research network and U.S.-based IReNA,” said Chiaki Kobayashi, chair of BRIDGCE’s steering committee and professor of astrophysics at The University of Hertfordshire (UK). “This bridge opens up excellent opportunities to exchange multidisciplinary knowledge and expertise, establish international connections and enhance training of the next generation of researchers. Our goal is to understand the origin of elements such as gold and platinum in the universe.”

    Since its founding in 2019, IReNA has improved communication across countries and disciplines to take advantage of developments in astronomy, nuclear experiments and theory. It is enabled by NSF’s AccelNet program dedicated to support strategic linkages among U.S. research networks and complementary networks abroad. IReNA employs a novel mechanism of connecting regional research networks across the world into a global network of networks.

    IReNA allows its new member networks to expand their access to laboratories and telescopes. IReNA benefits from the expanded pool of expertise and resources provided by the new member networks.

    “For CaNPAN to be able to join the IReNA network is a great opportunity to further collaboration between Canadian nuclear astrophysics researchers and their colleagues in the U.S. and around the world,” said Chris Ruiz, senior scientist at TRIUMF- Canada’s particle accelerator centre [Centre canadien d’accélération des particules](CA) and CaNPAN representative. “Also importantly, it connects students to their peers in the field and really fosters community among the future leaders of the field.”

    “We are excited to partner with IReNA to accelerate progress in our field,” said Daniel Bemmerer, ChETEC-INFRA representative and nuclear astrophysics group leader at The Helmholtz Center Dresden-Rossendorf [Helmholtz-Zentrum Dresden-Rossendorf](DE). “For example, we plan to offer complimentary access to ChETEC-INFRA infrastructures, partner in organizing meetings and improve the worldwide visibility of smaller European research institutions.”

    Nuclear astrophysics is a multidisciplinary field that addresses scientific questions at the intersection of nuclear physics and astrophysics. Research networks connecting nuclear physicists, astronomers and modelers are key to making progress.

    For example, when the observatories known as LIGO and Virgo announced the detection of gravitational waves from the collision of two neutron stars — neutron star merger GW170817 — in August 2017, the event was followed up by detection of electromagnetic emission by a coordinated network of ground and space-based telescopes.

    Caltech/MIT Advanced aLigo at Hanford, WA(US), Livingston, LA(US) and VIRGO Gravitational Wave interferometer, near Pisa(IT).

    This was the first cosmic event observed in both gravitational waves and light. Astronomy and nuclear astrophysics have since entered the multimessenger era. These multimessengers inform modelers about key nuclear physics input needed to understand how chemical elements are synthesized in such energetic cosmic events.

    More powerful accelerators and more sophisticated detectors at both radioactive and stable beam facilities allow for the measurements of short-lived nuclear species never before accessible. The Facility for Rare Isotope Beams, or FRIB, in the United States, for example, will soon produce some of these ephemeral rare isotopes.

    “There hasn’t been a more exciting time to be a researcher in this field,” said Hendrik Schatz, University Distinguished Professor with faculty appointments at FRIB and in MSU’s Department of Physics and Astronomy and director of IReNA and JINA-CEE. Schatz conducts nuclear research at FRIB. “We are at the crossroads of unprecedented scientific opportunities. By building networks of networks like IReNA, we are well-equipped to fully exploit these opportunities and to really accelerate science. We are also able to train the new generation of nuclear astrophysicists in a global and multidisciplinary environment.”

    IReNA is a National Science Foundation AccelNet Network of Networks. AccelNet is designed to accelerate the process of scientific discovery and prepare the next generation of U.S. researchers for multiteam international collaborations. The AccelNet program supports strategic linkages among U.S. research networks and complementary networks abroad that will leverage research and educational resources to tackle grand scientific challenges that require significant coordinated international efforts. Learn more at http://www.irenaweb.org.

    Michigan State University operates FRIB as a user facility for the Office of Nuclear Physics in the U.S. Department of Energy Office of Science.

    Hosting the most powerful heavy-ion accelerator, FRIB will enable scientists to make discoveries about the properties of rare isotopes in order to better understand the physics of nuclei, nuclear astrophysics, fundamental interactions and applications for society, including in medicine, homeland security and industry.

    The U.S. Department of Energy Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of today’s most pressing challenges. For more information, visit http://www.energy.gov/science.

    See the full article here .


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    Michigan State Campus

    The Michigan State University (US) is a public research university located in East Lansing, Michigan, United States. Michigan State University (US) was founded in 1855 and became the nation’s first land-grant institution under the Morrill Act of 1862, serving as a model for future land-grant universities.

    The university was founded as the Agricultural College of the State of Michigan, one of the country’s first institutions of higher education to teach scientific agriculture. After the introduction of the Morrill Act, the college became coeducational and expanded its curriculum beyond agriculture. Today, Michigan State University (US) is one of the largest universities in the United States (in terms of enrollment) and has approximately 634,300 living alumni worldwide.

    U.S. News & World Report ranks its graduate programs the best in the U.S. in elementary teacher’s education, secondary teacher’s education, industrial and organizational psychology, rehabilitation counseling, African history (tied), supply chain logistics and nuclear physics in 2019. Michigan State University (US) pioneered the studies of packaging, hospitality business, supply chain management, and communication sciences. Michigan State University (US) is a member of the Association of American Universities and is classified among “R1: Doctoral Universities – Very high research activity”. The university’s campus houses the National Superconducting Cyclotron Laboratory, the W. J. Beal Botanical Garden, the Abrams Planetarium, the Wharton Center for Performing Arts, the Eli and Edythe Broad Art Museum, the Facility for Rare Isotope Beams, and the country’s largest residence hall system.

    Research

    The university has a long history of academic research and innovation. In 1877, botany professor William J. Beal performed the first documented genetic crosses to produce hybrid corn, which led to increased yields. Michigan State University (US) dairy professor G. Malcolm Trout improved the process for the homogenization of milk in the 1930s, making it more commercially viable. In the 1960s, Michigan State University (US) scientists developed cisplatin, a leading cancer fighting drug, and followed that work with the derivative, carboplatin. Albert Fert, an Adjunct professor at MSU, was awarded the 2007 Nobel Prize in Physics together with Peter Grünberg.

    Today Michigan State University (US) continues its research with facilities such as the Department of Energy (US)-sponsored Plant Research Laboratory and a particle accelerator called the National Superconducting Cyclotron Laboratory [below]. The Department of Energy (US) Office of Science named Michigan State University as the site for the Facility for Rare Isotope Beams (FRIB). The $730 million facility will attract top researchers from around the world to conduct experiments in basic nuclear science, astrophysics, and applications of isotopes to other fields.

    In 2004, scientists at the Cyclotron produced and observed a new isotope of the element germanium, called Ge-60 In that same year, Michigan State University (US), in consortium with the University of North Carolina at Chapel Hill (US) and the government of Brazil, broke ground on the 4.1-meter Southern Astrophysical Research Telescope (SOAR) in the Andes Mountains of Chile.

    NSF NOIRLab NOAO Southern Astrophysical Research [SOAR ] telescope situated on Cerro Pachón, just to the southeast of Cerro Tololo on the NOIRLab NOAO AURA site at an altitude of 2,700 meters (8,775 feet) above sea level.
    The consortium telescope will allow the Physics & Astronomy department to study galaxy formation and origins. Since 1999, MSU has been part of a consortium called the Michigan Life Sciences Corridor, which aims to develop biotechnology research in the State of Michigan. Finally, the College of Communication Arts and Sciences’ Quello Center researches issues of information and communication management.


    The Michigan State University (US) Spartans compete in the NCAA Division I Big Ten Conference. Michigan State Spartans football won the Rose Bowl Game in 1954, 1956, 1988 and 2014, and the university claims a total of six national football championships. Spartans men’s basketball won the NCAA National Championship in 1979 and 2000 and has attained the Final Four eight times since the 1998–1999 season. Spartans ice hockey won NCAA national titles in 1966, 1986 and 2007. The women’s cross country team was named Big Ten champions in 2019. In the fall of 2019, MSU student-athletes posted all-time highs for graduation success rates and federal graduation rates, according to NCAA statistics.

     
  • richardmitnick 1:12 pm on May 11, 2021 Permalink | Reply
    Tags: "Connecting the smallest and largest scales", Astroparticle physics is undergoing a phase of profound transformation., EuCAPT-European Consortium for Astroparticle Theory, , LIGO and Virgo, The discovery of high-energy cosmic neutrinos with U Wiconsin IceCube., There are strong hints that explanations for dark matter and dark energy; high-energy cosmic rays; matter-antimatter asymmetry; and other enigmas at large lie in the domain of particle physics., We have witnessed the birth of Multi-messenger Astrophysics.   

    From European Organization for Nuclear Research (Organisation européenne pour la recherche nucléaire)(EU) [CERN]: “Connecting the smallest and largest scales” 

    Cern New Bloc

    Cern New Particle Event

    From European Organization for Nuclear Research (Organisation européenne pour la recherche nucléaire)(EU) [CERN]

    10 May, 2021
    Matthew Chalmers

    The first edition of the EuCAPT annual symposium on 5-7 May saw hundreds of physicists discuss the latest opportunities and challenges in theoretical astroparticle physics and cosmology.

    Established in 2019 with its central hub at CERN, the European Consortium for Astroparticle Theory (EuCAPT) aims to bring together the European community of theoretical astroparticle physicists and cosmologists to tackle some of the greatest mysteries in science.

    There are strong hints that explanations for dark matter and dark energy, the origin of high-energy cosmic rays, the matter-antimatter asymmetry, and other enigmas about the universe at large lie in the domain of particle physics. Addressing them therefore demands a highly interdisciplinary approach by a strong and diverse community.

    “Astroparticle physics is undergoing a phase of profound transformation”, says EuCAPT Director Gianfranco Bertone of the Centre for Gravitation and Astroparticle Physics at the University of Amsterdam [Universiteit van Amsterdam] (NL). “We have recently obtained extraordinary results, such as the discovery of high-energy cosmic neutrinos with IceCube and the direct detection of gravitational waves with LIGO and Virgo, and we have witnessed the birth of multi-messenger astrophysics. Yet we have formidable challenges ahead of us.”

    The symposium featured 29 invited presentations and 42 lightning talks given by young researchers, covering every aspect of astroparticle physics and cosmology, from early-universe inflationary dynamics to late-universe structure formation. The event also included a plenary session dedicated to the planning of a community-wide white paper, followed by thematic parallel discussions. An award ceremony congratulated Hannah Banks from the University of Cambridge, Francesca Capel from TU Munich and Charles Dalang from the University of Geneva [Université de Genève](CH) for the best talks by young scientists.

    “The symposium has been a successful opportunity for community building and for looking into the future of astroparticle physics and cosmology,” said Gian Giudice, the Head of CERN’s Theoretical Physics department. “The emphasis on the future was underlined by our choice of selecting almost all speakers from among young researchers.”

    EuCAPT is led by an international steering committee comprising 12 theorists from institutes in France, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom, and from CERN. Its aim is to coordinate scientific and training activities, help researchers attract adequate resources for their projects, and promote a stimulating and open environment in which young scientists can thrive. CERN will act as the central hub of EuCAPT for the first five years.

    See the full article here.


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    Meet CERN in a variety of places:

    Quantum Diaries
    QuantumDiaries

    Cern Courier


    THE FOUR MAJOR PROJECT COLLABORATIONS

    ATLAS

    ALICE

    CMS

    LHCb

    LHC

    OTHER PROJECTS AT CERN

    European Organization for Nuclear Research (Organisation européenne pour la recherche nucléaire)(EU)[CERN] AEGIS.


    CERN FASER is designed to study the interactions of high-energy neutrinos and search for new as-yet-undiscovered light and weakly interacting particles. Such particles are dominantly produced along the beam collision axis and may be long-lived particles, travelling hundreds of metres before decaying. The existence of such new particles is predicted by many models beyond the Standard Model that attempt to solve some of the biggest puzzles in physics, such as the nature of dark matter and the origin of neutrino masses.

     
  • richardmitnick 10:57 pm on February 18, 2021 Permalink | Reply
    Tags: "A Famous Black Hole Gets a Massive Update", , , , Black hole Cygnus X-1, , , LIGO and Virgo,   

    From The New York Times: “A Famous Black Hole Gets a Massive Update” 

    From The New York Times

    Feb. 18, 2021
    Dennis Overbye

    Cygnus X-1, one of the first identified black holes, is much weightier than expected, raising new questions about how such objects form.

    1
    An artist’s impression of the Cygnus X-1 system, a black hole with its orbiting companion star, HDE 226868, 7,200 light-years from Earth. Credit: ICRAR(AU).

    One of the biggest and first known black holes in the Milky Way galaxy is more massive than astronomers thought, a team of scientists announced on Thursday. The finding throws a wrench into long-held models of how massive stars evolve on the way to the ultimate doom.

    Cygnus X-1, an unseen, X-ray-emitting object, and a fat blue star called HDE 226868 circle each other every 5.6 days. Cygnus X-1 was one of the earliest celestial sources of X-rays ever discovered, in 1964, when astronomers began lofting cosmic Geiger counters into space, and one of the first to be considered as a possible black hole. The X-rays are produced by gas that is heated to millions of degrees as it swirls around the cosmic drain.

    With a mass originally estimated at 15 times that of the sun, Cygnus X-1 is one of the most massive and most luminous of the X-ray binary systems known in the Milky Way.

    New measurements have now raised that figure to 21 solar masses. The makeover does not change the overall perception of the cosmos; Cygnus X-1 is still a black hole, an almost science-fictional manifestation of Einsteinian weirdness in celestial reality. But the details of how Cygnus X-1 became a black hole are now in doubt.

    “A significant change in the mass of such a classic and historical astronomical source is a big deal (at least to astronomers),” Daniel Holz, a theoretical astrophysicist at the University of Chicago(US) who was not part of the study, wrote in an email.

    Also by email, James Miller-Jones of the ICRAR(AU) at Curtin University(AU) wrote: “We realized that a 21-solar-mass black hole was too massive to form in the Milky Way with the best existing estimates of the amount of mass lost by massive stars in stellar winds.”

    Dr. Miller-Jones and an international cast of colleagues reported the result in the journal Science and in a pair of companion papers in The Astrophysical Journal: Wind Mass-loss Rates of Stripped Stars Inferred from Cygnus X-1 . and Re-estimating the Spin Parameter of the Black Hole in Cygnus X-1 .

    Story of a black hole

    As one of the papers recounts, the story of Cygnus X-1 starts in the dim past with a pair of massive blue stars orbiting each other. The bigger of the two stars evolved faster, expanded and began spilling hydrogen gas onto its companion star. What remained of the primary star, which started out in its prime with a mass of 55 or 75 times that of the sun, shed more of its mass in fierce stellar winds as its core kept burning. Finally, having exhausted all of its thermonuclear fuel, the spent star collapsed into a black hole.

    Sometimes, depending on circumstance, this endgame collapse is marked by a stupendous supernova explosion.

    SN 1987A remnant, imaged by ALMA. The inner region is contrasted with the outer shell, lacy white and blue circles, where the blast wave from the supernova is colliding with the envelope of gas ejected from the star prior to its powerful detonation. Image credit: ALMA / ESO / NAOJ / NRAO / Alexandra Angelich, NRAO / AUI / NSF.

    In this case, however, Dr. Miller-Jones wrote in an email, “We think that the black hole formed via almost direct collapse into a black hole, rather than in a type II supernova explosion.” Such an explosion, he said, would have kicked the binary star pair out of an assemblage of similarly massive stars in which it formed and, apparently, still lives.

    Since then, the black hole has been feeding, pulling in gas from its puffed-up neighbor, which, with roughly 40 solar masses, has a lot to give, according to Dr. Miller-Jones.

    The new measurement of the mass of Cygnus X-1 was serendipitous. “We had not set out to remeasure the distance and black-hole mass,” Dr. Miller-Jones said. “But when we had analyzed our data, we realized its full potential.”

    In the spring of 2016, Dr. Miller-Jones and his group spent six days observing Cygnus X-1 with the National Radio Astronomy Observatory’s Very Long Baseline Array, a nationwide network of antennas operated out of Socorro, NM(US).

    NRAO/VLBA.

    They were trying to investigate the connection between X-ray-emitting gas flowing into the black hole and high-speed radio jets shooting out of it.

    But part of the process allowed them to triangulate the distance to Cygnus X-1, increasing it from about 6,000 light-years to a little over 7,000. Interestingly, Dr. Miller-James noted, this also brought the distance into better agreement with early results from the European Space Agency’s Gaia space telescope, whose measurements had been in mild tension with the previously accepted distance.

    ESA(EU)/GAIA satellite.

    When that change in distance was factored into the calculations of luminosity and mass, the black hole’s estimated mass grew by about 40 percent, to 21 solar masses.

    That was exciting, Dr. Miller-Jones said, but it was not until he talked to a theoretical colleague, Ilya Mandel of Monash University(AU), that he appreciated the full implications of what they had done.

    3
    Astronomers observed the Cygnus X-1 system from different angles, using the Earth’s orbit around the sun to measure the perceived movement of the system against the background stars. Credit: ICRAR(AU).

    The new estimate of mass put Cygnus X-1 above a kind of magic threshold. Astronomers know of a few dozen black hole X-ray binary systems in the Milky Way and nearby, all of which have imputed masses of less than 20 times that of the sun. That apparent limit suggested that it was hard for black holes to grow more massive, at least from the collapse of stars.

    But since 2016, the Laser Interferometer Gravitational-Wave Observatory, or LIGO, and Virgo antennas have been recording the collisions of black holes far out in space, many of them much larger than 20 solar masses.

    MIT /Caltech Advanced aLigo at Hanford, WA(US), Livingston, LA(US) and VIRGO Gravitational Wave interferometer, near Pisa(IT).

    “When the very first GW detection turned out to be a binary composed of two black holes, each of approximately 30 solar masses, it came as a profound shock to many in the community,” wrote Dr. Holz, who is part of a large team studying those results.

    Artist’s by now iconic conception of two merging black holes similar to those detected by LIGO. Credit: Caltech/MIT aLigo/Aurore Simonnet/Sonoma State.

    The contradiction was glaring. The LIGO results suggested that, in general, black holes were more massive than the X-ray results suggested. Much of what is assumed about stellar evolution comes from imagining the details of the cosmic winds that strip mass from dying stars as they sputter out and become black holes. The new results suggest that astronomers need to pare back their calculations of how stars lose their mass.

    “Having revised the mass of the black hole in Cygnus X-1 upward,” Dr. Miller-Jones said, “we realized that we would need to revise downward the mass-loss rate of massive stars in order to explain our measurements. This was the key insight that led us to write this paper, demonstrating the power of scientific collaboration, bringing a diverse range of skills together to attack an interesting problem.”

    Dr. Holz said he was not worried on behalf of the astronomers. The astrophysics of stellar evolution is very complicated, he noted, offering many knobs to turn in the calculations to help the results make sense. “As for making a black hole of this mass, my guess is that stellar modelers will be able to accommodate it without too much trouble,” he said. “They are a very creative bunch!”

    See the full article here .

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  • richardmitnick 4:46 pm on February 13, 2021 Permalink | Reply
    Tags: "In Violation of Einstein Black Holes Might Have ‘Hair’", According to Einstein’s general theory of relativity black holes have only three observable properties: mass; spin; and charge. Additional properties- or “hair”- do not exist., All of this could allow us to probe ideas such as string theory and quantum gravity in a way that has never been possible before., , Black hole hair hair could be detected by gravitational wave observatories., Black hole hair if it exists is expected to be incredibly short-lived lasting just fractions of a second., , ESA Lisa, Instabilities would effectively give some regions of a black hole’s horizon a stronger gravitational pull than others., Instabilities would make otherwise identical black holes distinguishable., LIGO and Virgo, , Some black holes might have instabilities on their event horizons., Yet scientists have begun to wonder if the “no-hair theorem” is strictly true.   

    From Quanta Magazine: “In Violation of Einstein Black Holes Might Have ‘Hair’” 

    From Quanta Magazine

    February 11, 2021
    Jonathan O’Callaghan

    1
    According to Einstein’s general theory of relativity, black holes have only three observable properties: mass, spin and charge. Additional properties, or “hair,” do not exist. Credit: Andriy_A/Shutterstock.

    Identical twins have nothing on black holes. Twins may grow from the same genetic blueprints, but they can differ in a thousand ways — from temperament to hairstyle. Black holes, according to Albert Einstein’s theory of general relativity, can have just three characteristics — mass, spin and charge. If those values are the same for any two black holes, it is impossible to discern one twin from the other. Black holes, they say, have no hair.

    “In classical general relativity, they would be exactly identical,” said Paul Chesler, a theoretical physicist at Harvard University. “You can’t tell the difference.”

    Yet scientists have begun to wonder if the “no-hair theorem” is strictly true. In 2012, a mathematician named Stefanos Aretakis — then at the University of Cambridge (UK) and now at the University of Toronto (CA) — suggested that some black holes might have instabilities [Horizon Instability of Extremal Black Holes] on their event horizons. These instabilities would effectively give some regions of a black hole’s horizon a stronger gravitational pull than others. That would make otherwise identical black holes distinguishable [Physical Review Letters].

    However, his equations only showed that this was possible for so-called extremal black holes — ones that have a maximum value possible for either their mass, spin or charge. And as far as we know, “these black holes cannot exist, at least exactly, in nature,” said Chesler.

    But what if you had a near-extremal black hole, one that approached these extreme values but didn’t quite reach them? Such a black hole should be able to exist, at least in theory. Could it have detectable violations of the no-hair theorem?

    A paper published late last month [Physical Review D] shows that it could. Moreover, this hair could be detected by gravitational wave observatories.

    MIT /Caltech Advanced aLigo at Hanford, WA (US), Livingston, LA, (US) and VIRGO Gravitational Wave interferometer, near Pisa, Italy.

    “Aretakis basically suggested there was some information that was left on the horizon,” said Gaurav Khanna, a physicist at the University of Massachusetts (US) and the University of Rhode Island (US) and one of the co-authors. “Our paper opens up the possibility of measuring this hair.”

    In particular, the scientists suggest that remnants either of the black hole’s formation or of later disturbances, such as matter falling into the black hole, could create gravitational instabilities on or near the event horizon of a near-extremal black hole. “We would expect that the gravitational signal we would see would be quite different from ordinary black holes that are not extremal,” said Khanna.

    If black holes do have hair — thus retaining some information about their past — this could have implications for the famous black hole information paradox put forward by the late physicist Stephen Hawking, said Lia Medeiros, an astrophysicist at the Institute for Advanced Study in Princeton, New Jersey (US). That paradox distills the fundamental conflict between general relativity and quantum mechanics, the two great pillars of 20th-century physics. “If you violate one of the assumptions [of the information paradox], you might be able to solve the paradox itself,” said Medeiros. “One of the assumptions is the no-hair theorem.”

    The ramifications of that could be broad. “If we can prove the actual space-time of the black hole outside of the black hole is different from what we expect, then I think that is going to have really huge implications for general relativity,” said Medeiros, who co-authored a paper in October [
    Physical Review Letters
    ] that addressed whether the observed geometry of black holes is consistent with predictions.

    Perhaps the most exciting aspect of this latest paper, however, is that it could provide a way to merge observations of black holes with fundamental physics. Detecting hair on black holes — perhaps the most extreme astrophysical laboratories in the universe — could allow us to probe ideas such as string theory and quantum gravity in a way that has never been possible before.

    “One of the big issues [with] string theory and quantum gravity is that it’s really hard to test those predictions,” said Medeiros. “So if you have anything that’s even remotely testable, that’s amazing.”

    There are major hurdles, however. It’s not certain that near-extremal black holes exist. (The best simulations at the moment typically produce black holes that are 30% away from being extremal, said Chesler.) And even if they do, it’s not clear if gravitational wave detectors would be sensitive enough to spot these instabilities from the hair.

    What’s more, the hair is expected to be incredibly short-lived, lasting just fractions of a second.

    But the paper itself, at least in principle, seems sound. “I don’t think that anybody in the community doubts it,” said Chesler. “It’s not speculative. It just turns out Einstein’s equations are so complicated that we’re discovering new properties of them on a yearly basis.”

    The next step would be to see what sort of signals we should be looking for in our gravitational detectors — either LIGO and Virgo, operating today, or future instruments like the European Space Agency’s space-based LISA instrument.

    Gravity is talking. Lisa will listen. Dialogos of Eide.


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

    “One should now build upon their work and really compute what would be the frequency of this gravitational radiation, and understand how we could measure and identify it,” said Helvi Witek, an astrophysicist at the University of Illinois, Urbana-Champaign (US). “The next step is to go from this very nice and important theoretical study to what would be the signature.”

    There are plenty of reasons to want to do so. While the chances of a detection that would prove the paper correct are slim, such a discovery would not only challenge Einstein’s theory of general relativity but prove the existence of near-extremal black holes.

    “We would love to know if nature would even allow for such a beast to exist,” said Khanna. “It would have pretty dramatic implications for our field.”

    See the full article here .


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    Formerly known as Simons Science News, Quanta Magazine is an editorially independent online publication launched by the Simons Foundation to enhance public understanding of science. Why Quanta? Albert Einstein called photons “quanta of light.” Our goal is to “illuminate science.” At Quanta Magazine, scientific accuracy is every bit as important as telling a good story. All of our articles are meticulously researched, reported, edited, copy-edited and fact-checked.

     
  • richardmitnick 11:49 am on February 4, 2021 Permalink | Reply
    Tags: "Einstein’s theory of general relativity unveiled a dynamic and bizarre cosmos", , , , , LIGO and Virgo, ,   

    From Science News: “Einstein’s theory of general relativity unveiled a dynamic and bizarre cosmos” 

    From Science News

    February 3, 2021
    Elizabeth Quill

    The predictions were right about black holes, gravitational waves and universe expansion.

    1
    Neutron stars (one illustrated) squash the mass equivalent of the sun into the size of a city. Credit: Casey Reed/Penn State.

    Albert Einstein’s mind reinvented space and time, foretelling a universe so bizarre and grand that it has challenged the limits of human imagination. An idea born in a Swiss patent office that evolved into a mature theory in Berlin set forth a radical new picture of the cosmos, rooted in a new, deeper understanding of gravity.

    Out was Newton’s idea, which had reigned for nearly two centuries, of masses that appeared to tug on one another. Instead, Einstein presented space and time as a unified fabric distorted by mass and energy. Objects warp the fabric of spacetime like a weight resting on a trampoline, and the fabric’s curvature guides their movements. With this insight, gravity was explained.

    Einstein presented his general theory of relativity at the end of 1915 in a series of lectures in Berlin. But it wasn’t until a solar eclipse in 1919 that everyone took notice. His theory predicted that a massive object — say, the sun — could distort spacetime nearby enough to bend light from its straight-line course. Distant stars would thus appear not exactly where expected. Photographs taken during the eclipse verified that the position shift matched Einstein’s prediction. “Lights all askew in the heavens; men of science more or less agog,” declared a New York Times headline.

    Even a decade later, a story in Science News Letter, the predecessor of Science News, wrote of Riots to understand Einstein theory (SN: 2/1/30, p. 79). Apparently extra police had to be called in to control a crowd of 4,500 who “broke down iron gates and mauled each other” at the American Museum of Natural History in New York City to hear an explanation of general relativity.

    By 1931, physicist Albert A. Michelson, the first American to win a Nobel Prize in the sciences, called the theory “a revolution in scientific thought unprecedented in the history of science.”

    But for all the powers of divination we credit to Einstein today, he was a reluctant soothsayer. We now know that general relativity offered much more than Einstein was willing or able to see. “It was a profoundly different way of looking at the universe,” says astrophysicist David Spergel of the Simons Foundation’s Flatiron Institute in New York City, “and it had some wild implications that Einstein himself didn’t want to accept.” What’s more, says Spergel (a member of the Honorary Board of the Society for Science, publisher of Science News), “the wildest aspects of general relativity have all turned out to be true.”

    What had been masquerading as a quiet, static, finite place is instead a dynamic, ever-expanding arena filled with its own riot of space-bending beasts. Galaxies congregate in superclusters on scales vastly greater than anything experts had considered before the 20th century. Within those galaxies reside not only stars and planets, but also a zoo of exotic objects illustrating general relativity’s propensity for weirdness, including neutron stars, which pack a fat star’s worth of mass into the size of a city, and black holes, which pervert spacetime so strongly that no light can escape. And when these behemoths collide, they shake spacetime, blasting out ginormous amounts of energy. Our cosmos is violent, evolving and filled with science fiction–like possibilities that actually come straight out of general relativity.

    “General relativity opened up a huge stage of stuff for us to look at and try out and play with,” says astrophysicist Saul Perlmutter of the University of California, Berkeley.

    Saul Perlmutter [The Supernova Cosmology Project] shared the 2006 Shaw Prize in Astronomy, the 2011 Nobel Prize in Physics, and the 2015 Breakthrough Prize in Fundamental Physics with Brian P. Schmidt and Adam Riess [The High-z Supernova Search Team] for providing evidence that the expansion of the universe is accelerating.

    He points to the idea that the universe changes dramatically over its lifetime — “the idea of a lifetime of a universe at all is a bizarre concept” — and the idea that the cosmos is expanding, plus the thought that it could collapse and come to an end, and even that there might be other universes. “You get to realize that the world could be much more interesting even than we already ever imagined it could possibly be.”

    _______________________________________________________________________________________________________
    An expanding picture

    Einstein’s equations of general relativity were a wellspring from which our current view of the cosmos has flowed. That the theory continues to supply so many rich questions is part of what makes it “just incredible,” says David Spergel, an astrophysicist at the Simons Foundation’s Flatiron Institute in New York City. Over the last century, we’ve detected cosmic beasts that defy the imagination. We’ve also learned some crucial facts about our cosmos: The universe is expanding, and at an accelerating rate. The universe began with a bang 13.8 billion years ago. And mysterious forms of matter and energy are shaping the cosmos in unexpected and largely unknown ways. Read about some of the milestones in our expanding picture, including Vera Rubin’s contributions.

    Dark Matter Background
    Fritz Zwicky discovered Dark Matter in the 1930s when observing the movement of the Coma Cluster., Vera Rubin a Woman in STEM denied the Nobel, some 30 years later, did most of the work on Dark Matter.

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


    Coma cluster via NASA/ESA Hubble.


    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.
    Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.
    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.

    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.


    ________________________________________________________________________________________________________
    General relativity has become the foundation for today’s understanding of the cosmos. But the current picture is far from complete. Plenty of questions remain about mysterious matter and forces, about the beginnings and the end of the universe, about how the science of the big meshes with quantum mechanics, the science of the very small. Some astronomers believe a promising route to answering some of those unknowns is another of general relativity’s initially underappreciated features — the power of bent light to magnify features of the cosmos.

    Today’s scientists continue to poke and prod at general relativity to find clues to what they might be missing. General relativity is now being tested to a level of precision previously impossible, says astrophysicist Priyamvada Natarajan of Yale ​University. “General relativity expanded our cosmic view, then gave us sharper focus on the cosmos, and then turned the tables on it and said, ‘now we can test it much more strongly.’ ” It’s this testing that will perhaps uncover problems with the theory that might point the way to a fuller picture.

    And so, more than a century after general relativity debuted, there’s plenty left to foretell. The universe may turn out to be even wilder yet.

    Ravenous beasts

    Just over a century after Einstein unveiled general relativity, scientists obtained visual confirmation of one of its most impressive beasts. In 2019, a global network of telescopes revealed a mass warping spacetime with such fervor that nothing, not even light, could escape its snare. The Event Horizon Telescope released the first image of a black hole, at the center of galaxy M87 (SN: 4/27/19, p. 6).

    EHT map.

    Messier 87*, The first image of the event horizon of a black hole. This is the supermassive black hole at the center of the galaxy Messier 87. Credit: JPL/ Event Horizon Telescope Collaboration released on 10 April 2019.

    “The power of an image is strong,” says Kazunori Akiyama, an astrophysicist at the MIT Haystack Observatory in Westford, Mass., who led one of the teams that created the image. “I somewhat expected that we might see something exotic,” Akiyama says. But after looking at the first image, “Oh my God,” he recalls thinking, “it’s just perfectly matching with our expectation of general relativity.”

    For a long time, black holes were mere mathematical curiosities. Evidence that they actually reside out in space didn’t start coming in until the second half of the 20th century. It’s a common story in the annals of physics. An oddity in some theorist’s equation points to a previously unknown phenomenon, which kicks off a search for evidence. Once the data are attainable, and if physicists get a little lucky, the search gives way to discovery.

    In the case of black holes, German physicist Karl Schwarzschild came up with a solution to Einstein’s equations near a single spherical mass, such as a planet or a star, in 1916, shortly after Einstein proposed general relativity. Schwarzschild’s math revealed how the curvature of spacetime would differ around stars of the same mass but increasingly smaller sizes — in other words, stars that were more and more compact. Out of the math came a limit to how small a mass could be squeezed. Then in the 1930s, J. Robert Oppenheimer and Hartland Snyder described what would happen if a massive star collapsing under the weight of its own gravity shrank past that critical size — today known as the “Schwarzschild radius” — reaching a point from which its light could never reach us. Still, Einstein — and most others — doubted that what we now call black holes were plausible in reality.

    The term “black hole” first appeared in print in Science News Letter. It was in a 1964 story by Ann Ewing, who was covering a meeting in Cleveland of the American Association for the Advancement of Science (SN: 1/18/64, p. 39). That’s also about the time that hints in favor of the reality of black holes started coming in.

    Just a few months later, Ewing reported the discovery of quasars — describing them in Science News Letter as “the most distant, brightest, most violent, heaviest and most puzzling sources of light and radio waves” (SN: 8/15/64, p. 106). Though not linked to black holes at the time, quasars hinted at some cosmic powerhouses needed to provide such energy. The use of X-ray astronomy in the 1960s revealed new features of the cosmos, including bright beacons that could come from a black hole scarfing down a companion star. And the motions of stars and gas clouds near the centers of galaxies pointed to something exceedingly dense lurking within.

    3
    Quasars (one illustrated) are so bright that they can outshine their home galaxies. Though baffling when first discovered, these outbursts are powered by massive, feeding black holes. Credit: Mark Garlick/Science Source.

    Black holes stand out among other cosmic beasts for how extreme they are. The largest are many billion times the mass of the sun, and when they rip a star apart, they can spit out particles with 200 trillion electron volts of energy. That’s some 30 times the energy of the protons that race around the world’s largest and most powerful particle accelerator, the Large Hadron Collider.

    CERN (CH) LHC Map


    SixTrack CERN (CH) LHC particles.

    As evidence built into the 1990s and up to today, scientists realized these great beasts not only exist, but also help shape the cosmos. “These objects that general relativity predicted, that were mathematical curiosities, became real, then they were marginal. Now they’ve become central,” says Natarajan.

    We now know supermassive black holes reside at the centers of most if not all galaxies, where they generate outflows of energy that affect how and where stars form. “At the center of the galaxy, they define everything,” she says.

    Sgr A* from ESO VLT.


    Star S0-2 Andrea Ghez Keck/UCLA Galactic Center Group at SGR A*, the supermassive black hole at the center of the Milky Way.


    SGR A and SGR A* from Penn State and NASA/Chandra.

    Though visual confirmation is recent, it feels as though black holes have long been familiar. They are a go-to metaphor for any unknowable space, any deep abyss, any endeavor that consumes all our efforts while giving little in return.

    Real black holes, of course, have given plenty back: answers about our cosmos plus new questions to ponder, wonder and entertainment for space fanatics, a lost album from Weezer, numerous episodes of Doctor Who, the Hollywood blockbuster Interstellar.

    For physicist Nicolas Yunes of the University of Illinois at Urbana-Champaign, black holes and other cosmic behemoths continue to amaze. “Just thinking about the dimensions of these objects, how large they are, how heavy they are, how dense they are,” he says, “it’s really breathtaking.”


    What does a black hole look like? [Updated] |
    Science News.

    Spacetime waves

    When general relativity’s behemoths collide, they disrupt the cosmic fabric. Ripples in spacetime called gravitational waves emanate outward, a calling card of a tumultuous and most energetic tango.

    Einstein’s math predicted such waves could be created, not only by gigantic collisions but also by explosions and other accelerating bodies. But for a long time, spotting any kind of spacetime ripple was a dream beyond measure. Only the most dramatic cosmic doings would create signals that were large enough for direct detection. Einstein, who called the waves “gravitationswellen”, was unaware that any such big events existed in the cosmos.

    6
    Gravitational waves ripple away from two black holes that orbit each other before merging (shown in this simulation). The merging black holes created a new black hole that’s much larger than those found in previous collisions. Credit: Deborah Ferguson, Karan Jani, Deirdre Shoemaker and Pablo Laguna/Georgia Tech, Maya Collaboration.

    Beginning in the 1950s, when others were still arguing whether gravitational waves existed in reality, physicist Joseph Weber sunk his career into trying to detect them. After a decade-plus effort, he claimed detection in 1969, identifying an apparent signal perhaps from a supernova or from a newly discovered type of rapidly spinning star called a pulsar. In the few years after reporting the initial find, Science News published more than a dozen stories on what it began calling the “Weber problem” (SN: 6/21/69, p. 593). Study after study could not confirm the results. What’s more, no sources of the waves could be found. A 1973 headline read, “The deepening doubt about Weber’s waves” (SN: 5/26/73, p. 338).

    Weber stuck by his claim until his death in 2000, but his waves were never verified. Nonetheless, scientists increasingly believed gravitational waves would be found. In 1974, radio astronomers Russell Hulse and Joseph Taylor spotted a neutron star orbiting a dense companion. Over the following years, the neutron star and its companion appeared to be getting closer together by the distance that would be expected if they were losing energy to gravitational waves. Scientists soon spoke not of the Weber problem, but of what equipment could possibly pick up the waves. “Now, although they have not yet seen, physicists believe,” Dietrick E. Thomsen wrote in Science News in 1984 (SN: 8/4/84, p. 76).

    It was a different detection strategy, decades in the making, that would provide the needed sensitivity. The Advanced Laser Interferometry Gravitational-wave Observatory, or LIGO, which reported the first confirmed gravitational waves in 2016, relies on two detectors, one in Hanford, Wash., and one in Livingston, La. Each detector splits the beam of a powerful laser in two, with each beam traveling down one of the detector’s two arms. In the absence of gravitational waves, the two beams recombine and cancel each other out. But if gravitational waves stretch one arm of the detector while squeezing the other, the laser light no longer matches up.

    MIT /Caltech Advanced aLigo .

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

    Caltech/MIT Advanced aLigo detector installation Hanford, WA, USA.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy.

    The machines are an incredible feat of engineering. Even spacetime ripples detected from colliding black holes might stretch an arm of the LIGO detector by as little as one ten-thousandth of the width of a proton.

    When the first detection, from two colliding black holes, was announced, the discovery was heralded as the beginning of a new era in astronomy.

    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 (IT) came online in August 2018.

    It was Science News’ story of the year in 2016, and such a big hit that the pioneers of the LIGO detector won the Nobel Prize in physics the following year.

    Scientists with LIGO and another gravitational wave detector, Virgo, based in Italy, have by now logged dozens more detections (SN: 1/30/21, p. 30). Most of the waves have emanated from mergers of black holes, though a few events have featured neutron stars. Smashups so far have revealed the previously unknown birthplaces of some heavy elements and pointed to a bright jet of charged subatomic particles that could offer clues to mysterious flashes of high-energy light known as gamma-ray bursts. The waves also have revealed that midsize black holes, between 100 and 100,000 times the sun’s mass, do in fact exist — along with reconfirming that Einstein was right, at least so far.

    Just five years in, some scientists are already eager for something even more exotic. In a Science News article about detecting black holes orbiting wormholes via gravitational waves, physicist Vítor Cardoso of Instituto Superior Técnico in Lisbon, Portugal, suggested a coming shift to more unusual phenomena: “We need to look for strange but exciting signals,” he said (SN: 8/29/20, p. 12).

    Gravitational wave astronomy is truly only at its beginnings. Improved sensitivity at existing Earth-based detectors will turn up the volume on gravitational waves, allowing detections from less energetic and more distant sources. Future detectors, including the space-based LISA, planned for launch in the 2030s, will get around the troublesome noise that interferes when Earth’s surface shakes.

    “Perhaps the most exciting thing would be to observe a small black hole falling into a big black hole, an extreme mass ratio inspiraling,” Yunes says. In such an event, the small black hole would zoom back and forth, back and forth, swirling in different directions as it followed wildly eccentric orbits, perhaps for years. That could offer the ultimate test of Einstein’s equations, revealing whether we truly understand how spacetime is warped in the extreme.

    See the full article here .


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  • richardmitnick 1:14 pm on January 8, 2021 Permalink | Reply
    Tags: "Radio telescopes could give us a new view of gravitational waves", ARCADE2 was a balloon experiment flown over Texas., , , LIGO and Virgo, , , , The EDGES radio telescope sheds light on primordial gravitational waves.   

    From physicsworld.com: “Radio telescopes could give us a new view of gravitational waves” 

    From physicsworld.com

    05 Jan 2021
    Edwin Cartlidge

    EDGES telescope in a radio quiet zone at the Murchison Radio-astronomy Observatory in Western Australia.


    Cosmic time machine: the EDGES radio telescope sheds light on primordial gravitational waves. Credit:Suzyj/CC BY-SA 4.0.

    The cosmic microwave background (CMB) is a rich source of information about the early universe, and now physicists in Switzerland and Germany reckon it could also serve as a detector of high-frequency gravitational waves, which are ripples in space–time.

    CMB per ESA/Planck.

    Indeed, the researchers have used pre-existing radio observations of the CMB to calculate new upper limits on the size of high-frequency primordial gravitational waves.

    The best developed technique for detecting gravitational waves, and the one used to discover them in 2015, relies on interferometry. In LIGO and other observatories, laser beams are deflected between mirrors at the ends of long (several kilometres) evacuated pipes and then interfere with one another.

    When a gravitational wave travels through the Earth it causes tiny changes in the distance between the mirrors, which is observed as changes in how the light interferes.

    The size of interferometers like LIGO makes them most sensitive to gravitational waves within a certain frequency band – from about 10 Hz to 10 kHz – meaning that much of the gravitational-wave spectrum remains unexplored. While the planned space-based LISA observatory will target lower frequencies in the millihertz range to detect waves from supermassive black holes, observations at megahertz, gigahertz or even higher frequencies could provide a window on exotic phenomena in the very young, hot universe.

    Gravity is talking. Lisa will listen. Dialogos of Eide.


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

    Detecting these high frequencies could also provide new insights into the fundamental constituents of nature, by allowing tests of the Standard Model of particle physics at energies beyond the most powerful particle colliders.

    Standard Model of Particle Physics via http://www.plus.maths.org .

    The Gertsenshtein effect

    To observe these higher frequencies, physicists have investigated a range of alternative approaches. This latest effort relies on the Gertsenshtein effect, which involves gravitational waves converting into electromagnetic waves (or vice versa) in the presence of a magnetic field.

    While other researchers have looked for this effect in the results of pre-existing terrestrial experiments, Valerie Domcke at the CERN laboratory in Geneva and Camilo Garcia Cely at DESY in Hamburg have come up with a way for detecting the effect at cosmic scales. The idea is to scrutinize the spectrum of the all-pervasive CMB, which was produced about 400,000 years after the Big Bang when electrons combined with protons to form neutral hydrogen. Whereas today’s leading cosmological model tells us that this spectrum should be that of a black body, significant cosmic conversion of gravitational to electromagnetic radiation at megahertz to gigahertz frequencies would instead raise the intensity of the CMB’s low frequency “tail”.

    The researchers specifically looked for distortions in the CMB spectrum generated before the first stars formed and hydrogen started reionizing, some 150 million years or so after the universe came into being. During these “dark ages” there were few free electrons to scatter photons, so the probability of oscillations occurring between gravitational and electromagnetic waves was higher than it would otherwise have been.

    EDGES and ARCADE2

    To set new limits on the size of gravitational waves at high frequencies, Domcke and Garcia Cely analysed data from two radio telescopes designed to peer far back in time. One, EDGES [above], consists of two dipole antennas and a dish located in the desert of Western Australia. The other, ARCADE2, was a balloon experiment flown over Texas.

    2
    Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE) is a program which utilizes high-altitude balloon instrument package intended to measure the heating of the universe by the first stars and galaxies after the big bang and search for the signal of relic decay or annihilation. In July 2006 a strong residual radio source was found using the radiometer, approximately six times what is predicted by theory. This phenomenon is known as “space roar” and remains an unsolved problem in astrophysics.

    The researchers found they could indeed use the data to set new limits, although they did have to make an assumption about the strength of cosmic magnetic fields. With the fields set low, their results were less stringent than those from putative terrestrial oscillations – the maximum amplitudes at 78 MHz (EDGES) and 3-30 GHz (ARCADE2) coming in at one part in 10^12 and 10^14 respectively. But with the fields set high, those limits dropped to one part in 10^21 and 10^24 respectively, the latter being seven orders of magnitude lower than limits imposed by the most sensitive laboratory experiment.

    Domcke and Garcia Cely argue that their new approach to gravitational-wave detection could improve substantially as radio telescopes become more sensitive – particularly as scientists develop new facilities to measure the 21 cm line in neutral hydrogen, which is central to studies of reionization. More sensitive telescopes would set tighter limits on primordial gravitational waves or could even reveal their existence. They say that this radiation could in principle be produced by sources such as merging light black holes or from clouds of dark matter around spinning black holes.

    They add that excess photons with frequencies below 10 GHz have been observed by both EDGES and ARCADE2. However, they point out that this excess would imply that gravitational waves have far more energy than that inferred from other cosmological observations. As a result, they say that astrophysical sources, “are a more likely explanation for the excess radiation observed”.

    A paper describing the work has been accepted for publication in Physical Review Letters.

    See the full article here .


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    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    We engage with policymakers and the general public to develop awareness and understanding of the value of physics and, through IOP Publishing, we are world leaders in professional scientific communications.
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  • richardmitnick 12:18 pm on November 7, 2020 Permalink | Reply
    Tags: "Eccentricity Spin and the Origins of Colliding Black Holes", , , , , , LIGO and Virgo   

    From AAS NOVA: “Eccentricity, Spin, and the Origins of Colliding Black Holes” 

    AASNOVA

    From AAS NOVA

    6 November 2020
    Susanna Kohler

    Artist’s iconic conception of two merging black holes similar to those detected by LIGO Credit: LIGO-Caltech/MIT/Sonoma State /Aurore Simonnet.

    The tally of merging black holes detected by the LIGO-Virgo gravitational-wave detectors continues to grow; the most recent data release brings the total to nearly 50 collisions! But how do these black-hole binaries form in the first place?

    1
    Still from a simulation showing how black holes might dynamically form as they interact in the chaotic cores of globular clusters. Credit: Carl Rodriguez/Northwestern Visualization.

    Two Formation Channels

    Before two black holes can collide in a burst of gravitational waves, they must first be bound together in an inspiraling binary pair.

    There are two leading theories for how such pairs of black holes might arise in our universe. In isolated binary evolution, two massive stars of a stellar binary independently evolve into black holes. In dynamical encounters, single black holes pair up into binaries through gravitational interactions in the center of a dense, crowded star cluster.

    Two Observational Clues

    How can we determine which formation channel produced the black-hole binaries we’ve detected so far? Two observational signatures, in particular, could point to a dynamical merger:

    1.Spin misalignment
    Due to conservation of angular momentum, black holes in isolated binaries are expected to have aligned spins. Black holes that pair up via dynamical encounters, on the other hand, are likely to have random, misaligned spins.
    2.Orbital eccentricity
    If a binary evolves in isolation, any initial eccentricity is damped long before the black holes merge. In the dynamical scenario, however, the abruptly formed binaries can merge before their orbits have time to circularize.

    Masses in the Stellar Graveyard GWTC-2 plot v1.0 BY LIGO-Virgo. Credit: Frank Elavsky and Aaron Geller at Northwestern University.

    The vast majority of mergers we’ve detected so far have had gravitational-wave signals consistent with low-mass, spin-aligned binaries with circular orbits — preventing us from differentiating between the two formation channels. One recent merger, however, is a promising candidate for further study: GW190521.

    One Intriguing Collision

    GW190521 has set records as a heavyweight: the merging components were ~85 and ~66 solar masses. These unusually large black holes already hint at a dynamical formation for the binary: it’s easier to explain black holes of this mass if they grew via successive mergers in a dense stellar environment.

    Now, a team of scientists led by Isobel Romero-Shaw (Monash University and OzGrav, Australia) has followed up on this clue, modeling the GW190521 signal with a variety of waveforms to explore the binary’s eccentricity and spin alignment.

    Romero-Shaw and collaborators show that we can’t currently differentiate between two models: one with non-zero eccentricity and aligned spins, and the other with a circular orbit but misaligned spins. Both models, however, are highly favored over models with circular orbits and aligned spins — which means that a dynamical formation channel is likely for GW190521.

    As LIGO-Virgo continues to amass detections, we may soon be able to build a statistical picture of how these black-hole binaries formed. But in the meantime, careful modeling of individual collisions like GW190521 are providing valuable insight.

    Citation

    “GW190521: Orbital Eccentricity and Signatures of Dynamical Formation in a Binary Black Hole Merger Signal,” Isobel Romero-Shaw et al 2020 ApJL 903 L5.

    https://iopscience.iop.org/article/10.3847/2041-8213/abbe26

    See the full article here .


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    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.
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  • richardmitnick 12:05 pm on November 6, 2020 Permalink | Reply
    Tags: "Debate Erupts Over How ‘Forbidden’ Black Holes Grow", LIGO and Virgo, Middleweight black holes have finally been detected.,   

    From Quanta Magazine: “Debate Erupts Over How ‘Forbidden’ Black Holes Grow” 

    From Quanta Magazine

    November 3, 2020
    Adam Mann

    Once missing in action, middleweight black holes have finally been detected. Now researchers are trying to figure out how they grow from small ones.

    1
    Credit: Samuel Velasco/Quanta Magazine.

    Until recently, black holes — those celestial spheres so dense that not even light can escape their gravitational pull — only seemed to come in size small or XXL. Astrophysicists inferred the presence of small “stellar” black holes weighing up to about 50 times the mass of the sun, as well as gargantuan black holes millions or billions of times heavier that sit in the centers of galaxies.

    “It’s like seeing infants and then seeing adults, but you don’t see the teenagers,” said Priyamvada Natarajan, an astrophysicist at Yale University.

    Then, on May 21, 2019, midsize black holes were unambiguously detected for the first time when the U.S.-based Laser Interferometer Gravitational-Wave Observatory (LIGO) and its European counterpart Virgo captured the tremor from a pair of black holes merging in the depths of space.

    MIT /Caltech Advanced aLigo .

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

    Caltech/MIT Advanced aLigo detector installation Hanford, WA, USA.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy.

    According to their analysis, the pair weighed 66 and 85 solar masses.

    Since the finding became official in September of this year, a debate has developed. The question is how intermediate-size black holes arise. Smaller black holes might grow to middleweight by guzzling gas and dust. Or they might inflate by consuming one another, enlarging with each successive merger. “Whether one of these processes is relevant, or both, is unclear,” said Imre Bartos, a physicist at the University of Florida. The genesis of intermediate-size black holes matters because it intersects with a number of other astrophysical plotlines.

    What’s certain is that the 66- and 85-solar-mass black holes must have grown somehow, because they couldn’t have formed at those sizes from the gravitational collapse of stars.

    Near the end of large stars’ lives, they fuse hydrogen in their cores into heavier and heavier elements. But once they reach iron, less energy comes out of fusion than goes in, and fusion stops. Unable to hold up the star’s weighty outer layers, the dense core gravitationally collapses, triggering a spectacular supernova explosion and leaving behind an ultra-compact and heavy remnant: the black hole.

    Messier 87*, The first image of the event horizon of a black hole. This is the supermassive black hole at the center of the galaxy Messier 87. Image via JPL/ Event Horizon Telescope Collaboration released on 10 April 2019.

    4
    Intermediate black hole Alain Riazuelo of Centre Nationnal de la Recherche Scientifique (FR) , via Wikipedia

    At least, that’s the case for stars up to a certain size. If the core of an enormous star is between 65 and 135 times the sun’s mass, it can reach astounding temperatures of nearly 300 million degrees Celsius, causing particles of light to spontaneously convert into pairs of electrons and positrons. With the disappearance of radiation pressure, the bulky outer layers gain the upper hand and fall inward with even greater ferocity than they do in a typical supernova. The entire core detonates like a bomb, completely incinerating the star and leaving nothing in its wake.

    Cores between about 50 and 65 solar masses undergo a series of partial explosions until they drop below the range where electron-positron formation occurs; they then gravitationally collapse into black holes. This means that, theoretically, black holes with between 50 and 135 solar masses can’t be created by stars.

    Yet even before the recent detection, many astrophysicists suspected that black holes in that forbidden range should exist. This is because they hypothesized that stellar black holes might grow into the supermassive ones that anchor galaxies by passing through a middle stage.

    Natarajan, who has long worked on intermediate-mass black hole growth models, collected her latest ideas in a paper posted online on September 19 [MNRAS]. She favors scenarios where small black holes are born in nuclear star clusters, dense collections of stars found near galactic centers. These initial pipsqueak black holes sweep through the cluster, growing fat on gas and dust, until they settle at a single location and stop gaining weight. Depending on how much material the cluster contains and how long the black hole wanders, intermediate entities with a wide range of final masses could develop, including potentially both of the black holes detected by LIGO/Virgo.

    But Bartos and other researchers working on “hierarchical merger” models, in which black holes grow by eating one another rather than by accruing gas and dust, point to one major supporting detail in the LIGO/Virgo data.

    Black holes can have angular momentum, or “spin,” that ranges between extremes designated 0 and 1. When two similar-size black holes combine, the spin of the resulting black hole is most likely to be around 0.7. The final black hole produced in the merger seen by LIGO/Virgo, for instance, had a spin of 0.72. But, tellingly, the two black holes involved in the merger had similar spins, pegged at 0.69 and 0.73, suggesting that they might have each formed in previous mergers.

    Masses in the Stellar Graveyard GWTC-2 plot v1.0 BY LIGO-Virgo Frank Elavsky and Aaron Geller at Northwestern University.

    “It looks like this event is consistent with the idea that black holes merge repeatedly,” said Emanuele Berti, an astrophysicist at Johns Hopkins University who studies hierarchical mergers.

    On the other hand, Berti notes that gas and dust accreting onto black holes should also affect their spins. Material falling into a black hole theoretically forms a rotating disk as it drains toward the central point, and this disk’s rotation can transfer to the hole. The details of this process have yet to be fully worked out, but infalling material could in principle be responsible for the observed spins. “We cannot conclude in all honesty that this was a second-generation merger,” Berti said.

    There’s another possible mark against the multi-merger theory: When two black holes with unequal masses orbit one another, Berti explained, they spray gravitational waves the way a rotating sprinkler sprays water, rather than radiating the waves symmetrically in all directions. “Then, at the moment of the merger, you shut off the water,” Berti said. “The gravity waves go one way and the [resulting black hole] goes another.” The black hole could end up moving with a speed of tens of millions of kilometers per hour, rapidly escaping whatever environment it’s in. Slowing it down enough for another merger would be difficult.

    Black holes that form in nuclear star clusters, Natarajan’s preferred birthplace, would be less liable to rocket off from gravitational kicks. That’s because such clusters occur in the vicinity of supermassive black holes, whose colossal influence could rein in speedy objects and potentially allow black holes to meet partners.

    A single merger event won’t settle the debate.

    “I think for now there’s a lot of different possible formation channels,” said Laura Blecha, a theoretical astrophysicist at the University of Florida. “That might be a different story even six months from now with new models or new LIGO detections.”

    Though the gravitational wave observatory is currently shut down due to the ongoing COVID-19 pandemic, upgrades over the next few years should increase its detection rate from roughly one black hole merger per week to one every hour.

    “There’s going to be an explosion of these events,” said Bartos.

    In the meantime, the current crop of data will continue to give astronomers lots to chew over. In late October, a reanalysis of LIGO/Virgo’s data by outside astronomers [GW190521 may be an intermediate mass ratio inspiral] suggested that the merger in question might have involved two black holes of extremely unequal weight — something like 16 and 166 times the sun’s mass, instead of 66 and 85 solar masses. If so, then both black holes could have arisen from stellar collapse, since their masses straddle the forbidden range. They needn’t have grown at all. Such a possibility would still require some explaining, though, since the heftier partner would have arisen from an unusually huge star. It all goes to show that researchers have only begun to peek into a previously invisible domain.

    See the full article here .


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    Formerly known as Simons Science News, Quanta Magazine is an editorially independent online publication launched by the Simons Foundation to enhance public understanding of science. Why Quanta? Albert Einstein called photons “quanta of light.” Our goal is to “illuminate science.” At Quanta Magazine, scientific accuracy is every bit as important as telling a good story. All of our articles are meticulously researched, reported, edited, copy-edited and fact-checked.

     
  • richardmitnick 10:43 am on October 3, 2020 Permalink | Reply
    Tags: , , , , , , LIGO and Virgo, , , ,   

    From Science Magazine: “With to-do list checked off, U.S. physicists ask, ‘What’s next?’” 

    From Science Magazine

    Oct. 2, 2020
    Adrian Cho

    SURF-Sanford Underground Research Facility, Lead, South Dakota, USA.


    1
    Physicists at the Stanford Underground Research Facility assemble the heart of the Lux-Zeplin dark matter detector, which will hold 7 tons of liquid xenon. Credit: Matthew Kapust/Sanford Underground Research Facility.

    LZ xenon detector in the Surface Assembly Lab cleanroom at SURF

    As U.S. particle physicists contemplate their future, they find themselves victims of their own surprising success. Seven years ago, the often fractious community hammered out its current research road map and rallied around it. Thanks to that unity—and generous budgets—the Department of Energy (DOE), the field’s main U.S. sponsor, has already started on almost every project on the list.

    So next week, as U.S. particle physicists start to drum up new ideas for the next decade in a yearlong Snowmass process—named for the Colorado ski resort where such planning exercises once took place—they have no single big project to push for (or against). And in some subfields, the next steps seem far less obvious than they were 10 years ago. “We have to be much more open minded about what particle physics and fundamental physics are,” says Young-Kee Kim of the University of Chicago and chair of the American Physical Society’s division of particles and fields, which is sponsoring the planning exercise.

    Ten years ago, the U.S. particle physics community was in disarray. The high-energy frontier had passed to CERN, the European particle physics laboratory near Geneva where, in 2012, the world’s biggest atom smasher, the Large Hadron Collider (LHC), blasted out the long-sought Higgs boson, the last piece in particle physicists’ standard model. Some physicists wanted the United States to build a huge experiment to fire elusive particles called neutrinos long distances through Earth to study how they “oscillate”—morph from one of their three types to another—as they zip along. Others wanted the United States to help push for the next big collider.

    CERN FCC Future Circular Collider details of proposed 100km-diameter successor to LHC.


    China Circular Electron Positron Collider (CEPC) map. It would be housed in a hundred-kilometer- (62-mile-) round tunnel at one of three potential sites. The documents work under the assumption that the collider will be located near Qinhuangdao City around 200 miles east of Beijing.


    ILC schematic, being planned for the Kitakami highland, in the Iwate prefecture of northern Japan.

    Those tensions came to a head during the last Snowmass effort in 2013, and the subsequent deliberations of the particle physics project prioritization panel (P5), which wrote the road map. U.S. researchers agreed to build the neutrino experiment, but make it bigger and better by inviting international partners. They also decided to continue to participate fully in the LHC, and to pursue a variety of smaller projects at home. The next collider would have to wait. Most important, DOE officials warned, the squabbling and backstabbing had to stop. In fact, physicists recall, the 2013 process had an informal motto: “Bickering scientists get nothing.”

    Physicists have just started to build the current plan’s centerpiece. The Long-Baseline Neutrino Facility (LBNF) at Fermi National Accelerator Laboratory (Fermilab) in Illinois will shoot the particles through 1300 kilometers of rock to the Deep Underground Neutrino Experiment (DUNE) in South Dakota, a detector filled with 40,000 tons of frigid liquid argon. LBNF/DUNE, which should come on in 2026, aims to be the definitive study of neutrino oscillations and whether they differ between neutrinos and antineutrinos, which could help explain how the universe generated more matter than antimatter.

    FNAL LBNF/DUNE from FNAL to SURF, Lead, South Dakota, USA.


    SURF DUNE LBNF Caverns at Sanford Lab.

    “The angst in the neutrino community is a lot lower than it was last time around,” says Kate Scholberg, a neutrino physicist at Duke University. “The DUNE program will be going on at least into the 2030s.” However, researchers are already thinking of upgrades to the $2.6 billion experiment, she notes.

    In other areas, the future looks less certain. The last time around, for example, scientists had a pretty clear path forward in their search for particles of dark matter—the so-far-unidentified stuff that appears to pervade the galaxies and bind them with its gravity. Researchers had built small underground detectors that searched for the signal of weakly interacting massive particles (WIMPs), the leading dark matter candidate, bumping into atomic nuclei. The obvious plan was to expand the detectors to the ton scale.

    Now, two multiton WIMP detectors are under construction. But so far WIMPs haven’t shown up, and scaling up that technology further “is probably not going to work very well anymore,” says Marcelle Soares-Santos, a physicist at the University of Michigan, Ann Arbor. “So we need to think a little bit more out of the box.” Researchers are now contemplating a hunt for other types of dark matter particles, using new detectors that exploit quantum mechanical effects to achieve exquisite levels of sensitivity.

    A perennial question for the field is what the next great particle collider will be. The obvious need is for one that fires electrons into positrons to crank out copious Higgs bosons and study their properties in detail, says Meenakshi Narain, a physicist at Brown University. But possible designs vary. Physicists in Japan are discussing such a Higgs factory in the form of a 30-kilometer-long linear electron-positron collider. Meanwhile, CERN has begun a study of an 80- to 100-kilometer circular collider. China has plans for a similar circular collider.

    However, Vladimir Shiltsev, an accelerator physicist at Fermilab, says those aren’t the only potential options. “The real picture is much murkier.” Snowmass organizers have received at least 16 different proposals for colliders, including one that would smash together muons—heavier, unstable cousins of electrons—and another that would use photons. Snowmass participants should consider all options, Shiltsev says.

    Joe Lykken, Fermilab’s deputy director for research, suggests physicists could even push for DOE to support a massive experiment that has nothing to do with particles: a next-generation detector of gravitational waves, ripples in spacetime set off when massive objects such as black holes spiral into each other. Their discovery in 2015 by the Laser Interferometer Gravitational-Wave Observatory (LIGO) opened a new window on the universe.

    LIGO consists of two L-shaped optical instruments with arms 4 kilometers long in Louisiana and Washington; it was built by the National Science Foundation. The next generation of ground-based detectors could be 10 times as big, and might better fit DOE, which specializes in scientific megaprojects, Lykken says. “It starts to sound like the kind of thing that the DOE would be interested in and maybe required for,” he says.

    During the coming year, Snowmass participants will air the more than 2000 ideas researchers have already proffered in two-page summaries. Then, a new P5 will formulate a new plan. Whatever ideas scientists come up with, to execute their new plan they’ll have to maintain the harmony that in recent years has made their planning process an exemplar to other fields. “Being unified is the new norm for us,” quips Jim Siegrist, DOE’s associate director for high energy physics. “So we have to continue to keep a lid on divisiveness and that’ll be a challenge.”

    MIT /Caltech Advanced aLigo .

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

    Caltech/MIT Advanced aLigo detector installation Hanford, WA, USA.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy.

    See the full article here.


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  • richardmitnick 12:12 pm on September 28, 2020 Permalink | Reply
    Tags: "Quantum entanglement realized between distant large objects", , LIGO and Virgo, , , University of Copenhagen DK   

    From Niels Bohr Institute DK: “Quantum entanglement realized between distant large objects” 

    University of Copenhagen DK

    Niels Bohr Institute bloc

    From Niels Bohr Institute DK

    28 September 2020
    Eugene Simon Polzik, Professor
    polzik@nbi.ku.dk
    Phone: +45 35 32 54 24
    Mobil: +45 23 38 20 45

    A team of researchers at the Niels Bohr Institute, University of Copenhagen, have succeeded in entangling two very different quantum objects. The result has several potential applications in ultra-precise sensing and quantum communication and is now published in Nature Physics.

    1
    Light propagates through the atomic cloud shown in the center and then falls onto the SiN membrane shown on the left. As a result of interaction with light the precession of atomic spins and vibration of the membrane become quantum correlated. This is the essence of entanglement between the atoms and the membrane. Credit: Niels Bohr Institute DK.

    Entanglement is the basis for quantum communication and quantum sensing. It can be understood as a quantum link between two objects which makes them behave as a single quantum object.

    Now, researchers from the Niels Bohr Institute DK, University of Copenhagen DK, have succeeded in making entanglement between two distinctly different and distant objects. One is a mechanical oscillator, a vibrating dielectric membrane, and the other is a cloud of atoms, each acting as a tiny magnet – what physicists call spin. These very different entities have now become possible to entangle by connecting them with photons, particles of light.Atoms can be useful in processing quantum information and the membrane – or mechanical quantum systems in general – can be useful for storage of quantum information.

    Professor Eugene Polzik, who led the effort, states that: “With this new technique, we are on route to pushing the boundaries of the possibilities of entanglement. The bigger the objects, the further apart they are, the more disparate they are, the more interesting entanglement becomes from both fundamental and applied perspectives. With the new result, entanglement between very different objects has become possible”.

    What is entanglement and how is it applied?

    In order to understand the full reach of the new result, it is important to understand exactly what the concept of entanglement means:

    Sticking to the example of spins entangled with a mechanical membrane, imagine the position of the vibrating membrane and the tilt of the total spin of all atoms, akin to a spinning top. If both objects move randomly, but we can observe that both of them move right or left at the same time, we call it a correlation. Such correlated motion is normally limited to the so-called zero-point motion – the residual, uncorrelated motion of all matter that occurs even at absolute zero temperature. This limits our knowledge about any of the systems. In their experiment, Eugene Polzik’s team has entangled the systems, which means that they move in a correlated way with a precision better than the zero-point motion. “Quantum mechanics is like a double-edged sword – it gives us wonderful new technologies, but also limits precision of measurements which would seem just easy from a classical point of view” – says a team member, Michał Parniak. Entangled systems can remain perfectly correlated even if they are at a distance from each other – a feature that has puzzled researchers from the very birth of quantum mechanics more than 100 years ago.

    PhD student Christoffer Østfeldt explains further: “Imagine the different ways of realizing quantum states as a kind of zoo of different realities or situations with very different qualities and potentials. If, for example, we wish to build a device of some sort, in order to exploit the different qualities they all possess and in which they perform different functions and solve a different task, it will be necessary to invent a language they are all able to speak. The quantum states need to be able to communicate, for us to use the full potential of the device. That’s what this entanglement between two elements in the zoo has shown we are now capable of”.

    A specific example of perspectives of entangling different quantum objects is quantum sensing. Different objects possess sensitivity to different external forces. For example, mechanical oscillators are used as accelerometers and force sensors, whereas atomic spins are used in magnetometers. When only one of the two different entangled objects is subject to external perturbation, entanglement allows it to be measured with a sensitivity not limited by the object’s zero-point fluctuations.

    The outlook for the future applications of the new technique

    There is a fairly immediate possibility for application of the technique in sensing both for tiny oscillators and big ones. One of the biggest scientific pieces of news in recent years was the first detection of gravity waves, made by the Laser Interferometer Gravitational-wave Observatory (LIGO).

    MIT /Caltech Advanced aLigo .

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

    Caltech/MIT Advanced aLigo detector installation Hanford, WA, USA.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy.

    VIRGO Gravitational Wave interferometer, near Pisa, Italy.

    LIGO senses and measures extremely faint waves caused by astronomical events in deep space, such as black hole mergers or neutron star mergers. The waves can be observed because they shake the mirrors of the interferometer. But even LIGO’s sensitivity is limited by quantum mechanics because the mirrors of the laser interferometer are also shaken by the zero-point fluctuations. Those fluctuations lead to noise preventing observation of the tiny motion of the mirrors caused by gravitational waves.

    Limitless precision in measurements likely to be achievable

    It is, in principle, possible to generate entanglement of the LIGO mirrors with an atomic cloud and thus cancel the zero-point noise of the mirrors in the same way as it does for the membrane noise in the present experiment. The perfect correlation between the mirrors and the atomic spins due to their entanglement can be used in such sensors to virtually erase uncertainty. It simply requires us to take information from one system and apply the knowledge to the other. In such a way, we could learn both about the position and the momentum of LIGO’s mirrors at the same time, entering a so-called quantum-mechanics-free subspace and taking a step towards limitless precision of measurements of motion. A model experiment demonstrating this principle is on the way at Eugene Polzik’s laboratory.

    See the full article here .


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    Stem Education Coalition

    Niels Bohr Institute Campus

    Niels Bohr Institute DK (Danish: Niels Bohr Institutet DK) is a research institute of the University of Copenhagen. The research of the institute spans astronomy, geophysics, nanotechnology, particle physics, quantum mechanics and biophysics.

    The Institute was founded in 1921, as the Institute for Theoretical Physics of the University of Copenhagen DK, by the Danish theoretical physicist Niels Bohr, who had been on the staff of the University of Copenhagen since 1914, and who had been lobbying for its creation since his appointment as professor in 1916. On the 80th anniversary of Niels Bohr’s birth – October 7, 1965 – the Institute officially became The Niels Bohr Institute. Much of its original funding came from the charitable foundation of the Carlsberg brewery, and later from the Rockefeller Foundation.

    During the 1920s, and 1930s, the Institute was the center of the developing disciplines of atomic physics and quantum physics. Physicists from across Europe (and sometimes further abroad) often visited the Institute to confer with Bohr on new theories and discoveries. The Copenhagen interpretation of quantum mechanics is named after work done at the Institute during this time.

    On January 1, 1993 the institute was fused with the Astronomic Observatory, the Ørsted Laboratory and the Geophysical Institute. The new resulting institute retained the name Niels Bohr Institute.

    The University of Copenhagen (UCPH) DK (Danish: Københavns Universitet) is the oldest university and research institution in Denmark. Founded in 1479 as a studium generale, it is the second oldest institution for higher education in Scandinavia after Uppsala University (1477). The university has 23,473 undergraduate students, 17,398 postgraduate students, 2,968 doctoral students and over 9,000 employees. The university has four campuses located in and around Copenhagen, with the headquarters located in central Copenhagen. Most courses are taught in Danish; however, many courses are also offered in English and a few in German. The university has several thousands of foreign students, about half of whom come from Nordic countries.

    The university is a member of the International Alliance of Research Universities (IARU), along with University of Cambridge, Yale University, The Australian National University, and UC Berkeley, amongst others. The 2016 Academic Ranking of World Universities ranks the University of Copenhagen as the best university in Scandinavia and 30th in the world, the 2016-2017 Times Higher Education World University Rankings as 120th in the world, and the 2016-2017 QS World University Rankings as 68th in the world. The university has had 9 alumni become Nobel laureates and has produced one Turing Award recipient

     
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