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  • richardmitnick 1:46 pm on October 6, 2018 Permalink | Reply
    Tags: , , , , Science News, The universe’s continued existence implies extra dimensions are tiny, This could be the way the world ends., Where the black hole just was a bubble of space with entirely different laws of physics than the universe we inhabit would begin to grow expanding ever-outward at the speed of light. In its wake atoms   

    From Science News: “The universe’s continued existence implies extra dimensions are tiny” 

    From Science News

    October 5, 2018
    Lisa Grossman

    POP GOES THE UNIVERSE If extra dimensions were large enough, a universe with different laws of physics could bubble up from the death of a black hole. That would be bad news for us: The new version would be uninhabitable. Vectorpocket/shutterstock

    This could be the way the world ends.

    First, a pair of cosmic protons smash together at unimaginable speeds. The tremendous energy of their crash would create a tiny, ephemeral black hole, so small that it would last just a fraction of a second before evaporating.

    Where the black hole just was, a bubble of space with entirely different laws of physics than the universe we inhabit would begin to grow, expanding ever-outward at the speed of light. In its wake, atoms would disintegrate, and the universe as we know it would fizzle out of existence.

    “If you’re standing nearby when the bubble starts to expand, you don’t see it coming,” says Katie Mack, a physicist at North Carolina State University in Raleigh. “If it’s coming at you from below, your feet stop existing before your mind realizes that.”

    That horror movie can happen only if the universe has at least one extra dimension, on top of three of space and one of time.

    But this isn’t the way the world ends — at least it hasn’t yet.

    And so the fact that the universe hasn’t been destroyed by evaporating black holes puts strict limits on the size of extra dimensions, if any actually exist, Mack and Robert McNees of Loyola University Chicago claim in a paper posted online at arXiv.org September 13.

    Scientists have yet to find evidence of extra dimensions, a lack that suggests that any real ones must be minuscule. But their existence could help explain mysteries like dark energy and dark matter, and point the way to new physics beyond the standard model of particle physics (SN: 9/29/18, p. 18), so physicists are eager to probe their properties any way they can.

    Even tiny extra dimensions could have an influence on the universe, physicists suspect. For instance, gravity could leak into these extra dimensions, perhaps explaining why that force appears so much weaker than the other fundamental forces (SN: 9/29/18, p. 8).

    That leakage could also lower the bar for creating miniature black holes — at the tiny distances that the extra dimensions affect, gravity would appear much stronger. “If you have these extra dimensions, you don’t need to get as much matter in as small a space to make a black hole as you would without the extra dimensions,” Mack says.

    That’s why some people thought the Large Hadron Collider at CERN near Geneva might make tiny black holes when it turned on in 2008, but so far none have appeared (SN Online: 6/24/08).

    Nature can collide particles with even higher energies, though. The highest are found in ultrahigh energy cosmic rays, protons that zip between galaxies with energies higher than 8 billion billion electron volts (SN: 10/14/17, p. 7). That’s 100 million times as high as the energies produced by the LHC. If collisions between those particles have made any black holes, then physicists could work out the gravitational reach of any extra dimensions, or how close you have to get to an object before gravity starts acting weird.

    This scenario has a dark side. According to a theory first put forward by Stephen Hawking in the 1970s, energy radiates away from a black hole until the black hole eventually disappears (SN: 4/14/18, p. 12). The smaller the black hole, the faster it evaporates, so any black holes made by colliding cosmic rays would fizzle almost instantaneously, or so the theory goes.

    That could be bad news for the universe. In 2015, theoretical physicist Ruth Gregory of Durham University in England and her colleagues showed mathematically that when black holes evaporate, they can nudge the universe into a state in which the laws of physics are so different that atoms no longer hold together.

    “No structures can exist,” Mack says. “We’d just blink out of existence.”

    This catastrophe is called vacuum decay. It relies on the idea that the fundamental nature of the universe, called its vacuum state, might not be the most stable one possible. There could be another configuration of physical laws, the true vacuum, that sits in a lower energy state.

    Evaporating black holes could provide the bump needed to create a bubble of this true vacuum, Gregory and her colleagues argued. And once some true vacuum exists, the space around it would want to join the true vacuum. The bubble would expand outward at the speed of light, taking the known universe with it.

    “The black holes are quite naughty,” Gregory says. “They really want to seed vacuum decay. It’s a very strong process, if it can proceed.”

    That set of ideas leads to a paradox, Mack and McNees realized. Collisions between ultrahigh energy cosmic rays “should have happened thousands of times,” McNees says. If extra dimensions exist, and if they are large enough for ultrahigh energy cosmic rays to make mini black holes, then vacuum decay should already have happened. The fact that we’re here to wonder about it means that extra dimensions, if they exist, must be even smaller than previously thought.

    Mack and McNees calculated that any extra dimensions must be smaller than about 16 nanometers, or billionths of a meter. In other words, the gravitational influence of the extra dimensions would extend only that far. That’s hundreds of times smaller than the previous best estimates and rules out some of the theories that let gravity leak into extra dimensions.

    The analysis is fun and thorough, says cosmologist Ian Moss of Newcastle University in England, who worked with Gregory on the 2015 paper. But he’s worried that Mack and McNees make too many assumptions about what conditions would lead to vacuum decay.

    “You can’t really say that these limits are totally convincing,” he says. “There’s nothing wrong, but there’s so many ifs.”

    See the full article here .


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  • richardmitnick 1:16 pm on October 6, 2018 Permalink | Reply
    Tags: , , , , , Science News   

    From Science News: “A new ultrafast laser emits pulses of light 30 billion times a second” 

    From Science News

    October 5, 2018
    Emily Conover

    The devices pulsate at a higher rate than ever before, thanks to a novel technique.

    FINE-TOOTH COMB An ultrafast laser pulsates faster than any of its predecessors. The new device isolates light of particular frequencies (peaks in blue curves) to create a frequency comb made up of discrete colors of light (vertical bands). Scientists had to eliminate jitter in their experiment to make the comb (progression left to right). D. Carlson/NIST

    Blazingly fast lasers have just leveled up.

    Ultrafast lasers emit short, rapid-fire bursts of light, with each pulse typically lasting tens of millionths of a billionth of a second. A new laser pulses 30 billion times a second — about 100 times as fast as most ultrafast lasers, researchers report in the Sept. 28 Science.

    The speed boost was thanks to a new technique for making ultrafast lasers. Typically, researchers use a technique called mode locking, in which light bounces back and forth in a mirrored cavity in such a way that the light waves build on each other to create short flashes. The new method takes a more “brute force” approach, says study coauthor David Carlson, a physicist at the National Institute of Standards and Technology in Boulder, Colo., by essentially carving up a continuous laser beam into individual pulses.

    Ultrafast lasers can produce what’s known as a frequency comb, light made up of discrete colors. Those evenly spaced hues look like the teeth of a comb when plotted. To make the new approach work, the scientists had to eliminate electronic jitter that would otherwise smear out the comb’s sharp teeth.

    These combs can be used as a kind of “ruler” for light, and are so useful for precisely measuring the frequency of light that part of the 2005 Nobel Prize in physics was awarded to two researchers who had developed the technique (SN: 10/8/05, p. 229). Part of the 2018 Nobel Prize in physics was also awarded to ultrafast laser research, for a method to produce very intense, short laser pulses. But that technology was not used in this work (SN Online: 10/2/2018).

    The faster pulses achieved with the new technique result in a frequency comb with more widely spaced teeth. That property could be useful for calibrating telescope instruments called spectrographs, which slice up light from stars into various colors, aiding scientists in observations such as the hunt for planets beyond the solar system. Those spectrographs can’t distinguish frequencies that are too close together, so the instruments require a wide comb.

    Faster pulses could also speed up certain kinds of imaging of biological tissues. And the laser could be useful for telecommunications, says physicist and electrical engineer Andrew Weiner of Purdue University in West Lafayette, Ind., who called the work a “tour de force.” Each color of light could carry its own stream of information in a fiber-optic cable.

    The researchers “have achieved this amazing level of performance,” says physicist Victor Torres-Company of Chalmers University of Technology in Gothenburg, Sweden. “It’s up to us to think and dream what we could do with this light source.”

    Related journal articles
    See the full article for further references with links.

    See the full article here .


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  • richardmitnick 6:46 pm on September 30, 2018 Permalink | Reply
    Tags: , , , , How Much SETI Has Been Done? Finding Needles in the n-Dimensional Cosmic Haystack, , Science News,   

    From Science News: “We may not have found aliens yet because we’ve barely begun looking” 

    From Science News

    September 30, 2018
    Lisa Grossman

    A new calculation compares the effort so far to exploring a hot tub’s–worth of Earth’s oceans.

    NAIC Arecibo Observatory operated by University of Central Florida, Yang Enterprises and UMET, Altitude 497 m (1,631 ft)

    With no luck so far in a six-decade search for signals from aliens, you’d be forgiven for thinking, “Where is everyone?”

    A new calculation shows that if space is an ocean, we’ve barely dipped in a toe. The volume of observable space combed so far for E.T. is comparable to searching the volume of a large hot tub for evidence of fish in Earth’s oceans, astronomer Jason Wright at Penn State and colleagues say in a paper posted online September 19 at arXiv.org.

    “If you looked at a random hot tub’s worth of water in the ocean, you wouldn’t always expect a fish,” Wright says.

    Still, that’s far more space searched than calculated in 2010 for the 50th anniversary of the search for extraterrestrial intelligence, or SETI. In that work, SETI pioneer Jill Tarter and colleagues imagined a “cosmic haystack” of naturally occurring radio waves she could sift through for the proverbial needle of an artificial, alien beacon (SN Online: 5/29/12).

    SETI’s Jill Tarter

    Her haystack went beyond physical space to include factors such as a possible signal’s duration, frequency, variations and strength, as well as the sensitivity of radio telescopes on Earth that would presumably detect a signal.

    Wow! signal

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

    She concluded that searches had covered about a drinking glass’s worth of seawater — hardly enough to conclude the ocean is fishless.

    Wright and colleagues Shubham Kanodia and Emily Lubar updated Tarter’s calculation by devising a slightly different haystack, including factors like the frequency and bandwidth aliens might broadcast in. It also included more recent SETI searches such as the Breakthrough Listen project (SN Online: 7/20/15).

    Breakthrough Listen Project


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

    GBO radio telescope, Green Bank, West Virginia, USA

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

    Converting the volume to liters for the sake of analogy, the researchers concluded that SETI has covered the equivalent of 7,700 liters out of 1.335 billion trillion liters of water in Earth’s oceans.

    “We’re finally getting to the point today … that we have a chance of finding something, depending on how much there is to find,” Wright says.

    Laser SETI, the future of SETI Institute research

    See the full article here .


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  • richardmitnick 3:28 pm on September 20, 2018 Permalink | Reply
    Tags: , , , , , , Science News   

    From Science News: “Three new physics experiments could revamp the standard model” 

    From Science News

    September 19, 2018
    Emily Conover

    Physicists build giant machines to study tiny particles.

    MASSIVE MACHINES A researcher stands in the cavernous spectrometer of KATRIN, an experiment in Germany to measure the mass of particles called neutrinos. Michael Zacher

    Diana Parno’s head swam when she first stepped inside the enormous, metallic vessel of the experiment KATRIN. Within the house-sized, oblong structure, everything was symmetrical, clean and blindingly shiny, says Parno, a physicist at Carnegie Mellon University in Pittsburgh. “It was incredibly disorienting.”

    Now, electrons — thankfully immune to bouts of dizziness — traverse the inside of this zeppelin-shaped monstrosity located in Karlsruhe, Germany. Building the experiment took years and tens of millions of dollars. Why create such an extreme apparatus? It’s all part of a bid to measure the mass of itty-bitty subatomic particles known as neutrinos.

    KATRIN, which is short for Karlsruhe Tritium Neutrino Experiment, started test runs in May. The experiment is part of a multipronged approach to the study of particle physics, one of dozens of detectors built in an assortment of odd-looking shapes and sizes. Their mission: dive deep into the standard model, particle physicists’ theory of the subatomic building blocks of matter — and maybe overthrow it.

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

    Standard Model of Particle Physics from Symmetry Magazine

    Developed in the 1960s and ’70s, the standard model has some sizable holes: It can’t explain dark matter — an ethereal substance so far detected only by its gravitational effects — or dark energy, a mysterious oomph that causes the cosmos to expand at an increasing rate. The theory also can’t explain why the universe is made mostly of matter, while antimatter is rare (SN: 9/2/17, p. 15). So physicists are on a quest to revamp particle physics by probing the standard model’s weak points.

    Major facilities like the Large Hadron Collider — the gargantuan accelerator located at CERN near Geneva — haven’t yet found where the standard model goes wrong (SN: 10/1/16, p. 12).


    CERN map

    CERN LHC Tunnel

    CERN LHC particles

    Instead, particle physics experiments have confirmed standard model predictions again and again. “In some sense we are victims of our own success,” says Juan Rojo, a theoretical physicist at Vrije Universiteit Amsterdam. “We don’t have hints about what is the next step.”

    New experiments like KATRIN might be able to ferret out answers. Also joining the ranks are Muon g-2 (pronounced “gee minus two”) at Fermilab in Batavia, Ill., and Belle II in Tsukuba, Japan.

    FNAL Muon g-2 studio

    SuperKEKB accelerator Belle II Credit KEK

    A behind-the-scenes look at these experiments reveals the sweat, joy and sacrifice that goes into each of these difficult enterprises. These efforts involve hundreds of researchers, sport price tags in the tens of millions of dollars and require major technological undertakings: intricate electronics, powerful magnets and ultraclean conditions. Researchers have built complex apparatuses with their own hands, lugged tons of equipment across continents and cleaned the insides of detectors until they gleam.

    Here’s a glimpse at three of the latest standard model challengers.

    Belle II

    KEK High Energy Accelerator Research Organization
    Tsukuba, Japan
    Approximate cost: $50 million

    Belle II KEK High Energy Accelerator Research Organization Tsukuba, Japan

    How it works

    Electrons and their antimatter partners, positrons, take laps around a 3-kilometer long, ring-shaped accelerator and collide at the center of the Belle II detector, producing a class of particles called B mesons. These particles contain a bottom quark, an exotic particle not found in run-of-the-mill matter. Scientists sift through the data produced when B mesons decay inside the 8-meter-tall detector to learn about the particles’ weird ways.

    T. Tibbitts, High Energy Accelerator Research Organization, Institute of Particle and Nuclear Studies

    1. An accelerator sends electrons from one end and positrons from the other into Belle II.

    2. Tracking detectors follow particles’ paths after collision, pinpointing B mesons.

    3. Quartz sensors distinguish between similar types of particles.

    4. A calorimeter measures energies of particles.

    5. Outer layers spot particles that get past inner sections.


    OK, but why?

    Certain B mesons seem to prefer to decay into electrons, rather than their heavier cousins, muons (SN: 5/13/17, p. 16). That goes against the standard model, which says electrons and muons should appear in equal amounts. If this unexpected behavior holds up to scrutiny, something big must be wrong with the theory. B mesons also partake in a process called CP violation, in which antimatter and matter don’t behave like perfect mirror images.

    Studying CP violation might help scientists understand why the universe is composed of matter and not antimatter. In the Big Bang, matter and antimatter were produced in equal measure and should have annihilated into nothingness, but somehow matter gained an upper hand. It’s “the most fundamental question human beings can ask … ‘Why are we here?’ ” says physics graduate student Robert Seddon.

    NARROW FOCUS Scientists insert superconducting magnets into the center of Belle II. The magnets focus the beams of electrons and positrons that collide inside the detector. KEK IPNS


    Karlsruhe Institute of Technology, Germany
    Approximate cost: $70 million

    KATRIN experiment aims to measure the mass of the neutrino using a huge device called a spectrometer (interior shown)Karlsruhe Institute of Technology, Germany

    How it works

    Physicists aim to measure the mass of neutrinos, wily subatomic particles that are nearly impossible to detect. At one end of the 70-meter-long KATRIN, radioactive decays of tritium produce electrons and the antimatter twins of neutrinos. Those antineutrinos escape while the electrons cruise through KATRIN’s blimp-shaped tank and are detected at the other end (SN Online: 10/18/16). The tank, a spectrometer, divvies up the particles according to their energies. Some energy from each tritium decay goes to generating the antineutrino’s mass. That limits how much energy the electron gets. So measuring the electrons’ energies can reveal the mass of neutrinos. KATRIN should officially start taking data next spring.


    T. Tibbitts, M. Arenz et al/J. of Instrumentation 2016

    1. Tritium decays, releasing electrons and antineutrinos, which escape.

    2. Electrons travel along beamline to spectrometer.

    3. The spectrometer sorts electrons by their energies

    4. A magnetic field (dotted lines) shepherds high-energy electrons to a detector at the other end.

    5. An electric field turns low-energy electrons back.

    6. Magnets focus electrons onto the detector.


    OK, but why?

    A neutrino’s mass is a tiny fraction of an electron’s. “Why is it so light?” Parno asks. “That’s mysterious.” The standard model initially predicted that neutrinos have no mass at all. But measurements indicate that the particles must have mass, though how much is still a question. Neutrinos barely interact with matter and are incredibly numerous: Billions of neutrinos sail through your thumbnail each second. These particles are so quirky that scientists want to know more.
    Radioactive rules

    It all starts with tritium. This radioactive version of hydrogen, pumped through the experiment in a gaseous form, emits 100 billion antineutrino and electron pairs each second. In the tritium lab, special rules are in place because of the radioactivity — scientists enter via an air lock and must wash their hands when they leave. The place has a spaceship vibe, says Larisa Thorne, a physics graduate student at Carnegie Mellon University. “I did feel quite like I was on Star Trek.”

    Muon g-2

    Fermilab, Batavia, Ill.
    Approximate cost: $46 million

    MOVING DAY A crane lifts the 50-ton apparatus containing Muon g-2’s magnetic ring, at the start of a cross-country journey to move the ring from Brookhaven National Laboratory in New York to Fermilab in Illinois. Brookhaven National Laboratory [ Muon g-2 started life at CERN]

    How it works

    Muons, heavier relatives of electrons, behave like tiny magnets with a north and south pole. Muon g-2, which started up in February, studies the properties of those minimagnets. Researchers beam thousands of muons into a doughnut-shaped electromagnet about as wide as the width of a basketball court. As muons circulate inside the electromagnet, their poles pivot like wobbling tops. Muons are unstable, so as they circulate, they decay into lighter particles known as positrons. The angles at which those positrons fly off can reveal the rate of the muons’ magnetic gyrations and, therefore, the strength of the muons’ magnets. The researchers will compare the measurement to predictions based on the standard model.

    1. Muons enter the magnet.

    2. Muons circle in the same direction repeatedly.

    3. Muons decay into positrons, which are picked up by detectors that measure energy and particle tracks.
    [Image of the Muon G-2 studio at FNAL is above]

    OK, but why?

    Transient particles blip in and out of existence everywhere in space. Those particles tweak the rate at which the muons gyrate. If undetected particles are out there, Muon g-2’s measurement might not square with predictions. A similar experiment performed at Brookhaven National Laboratory in Upton, N.Y., in the 1990s hinted at a mismatch (SN: 2/17/01, p. 102). Muon g-2 will make a more precise measurement to follow up on that lead.
    One ring

    Muon g-2’s magnetic field is about 30,000 times as strong as Earth’s magnetic field. Such strength is useful only if the magnetic field is ultrauniform. So physicists strategically placed thousands of tiny metal shims — many just a fraction of the thickness of notebook paper — to adjust the magnetic field. Hours of “shimming” left physicists’ hands “covered in dirt and oil and grease,” says physics graduate student Rachel Osofsky of the University of Washington in Seattle. The dirty job was worth it: The magnetic field is now uniform to within 0.0015 percent.

    See the full article here .


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  • richardmitnick 2:36 pm on September 14, 2018 Permalink | Reply
    Tags: , , , , Nuclear pasta in neutron stars may be the strongest material in the universe, , , Science News   

    From Science News: “Nuclear pasta in neutron stars may be the strongest material in the universe” 

    From Science News

    September 14, 2018
    Emily Conover

    Simulations suggest the theoretical substance is 10 billion times as strong as steel.

    TOUGH STUFF An exotic substance thought to exist within a type of collapsed star called a neutron star (illustrated) may be stronger than any other known material.
    Casey Reed/Penn State University, Wikimedia Commons

    A strand of spaghetti snaps easily, but an exotic substance known as nuclear pasta is an entirely different story.

    Predicted to exist in ultradense dead stars called neutron stars, nuclear pasta may be the strongest material in the universe. Breaking the stuff requires 10 billion times the force needed to crack steel, for example, researchers report in a study accepted in Physical Review Letters.

    “This is a crazy-big figure, but the material is also very, very dense, so that helps make it stronger,” says study coauthor and physicist Charles Horowitz of Indiana University Bloomington.

    Neutron stars form when a dying star explodes, leaving behind a neutron-rich remnant that is squished to extreme pressures by powerful gravitational forces, resulting in materials with bizarre properties (SN: 12/23/17, p. 7).

    About a kilometer below the surface of a neutron star, atomic nuclei are squeezed together so close that they merge into clumps of nuclear matter, a dense mixture of neutrons and protons. These as-yet theoretical clumps are thought to be shaped like blobs, tubes or sheets, and are named after their noodle look-alikes, including gnocchi, spaghetti and lasagna. Even deeper in the neutron star, the nuclear matter fully takes over. The burnt-out star’s entire core is nuclear matter, like one giant atomic nucleus.

    Nuclear pasta is incredibly dense, about 100 trillion times the density of water. It’s impossible to study such an extreme material in the laboratory, says physicist Constança Providência of the University of Coimbra in Portugal who was not involved with the research.
    Al dente

    When atomic nuclei get squeezed together inside a neutron star, scientists think that globs of nuclear matter form into shapes reminiscent of various types of pasta, including gnocchi (left in these simulations of nuclear pasta), spaghetti (middle) and lasagna (right).

    M.E. Caplan and C.J. Horowitz/Reviews of Modern Physics 2017

    Instead, the researchers used computer simulations to stretch nuclear lasagna sheets and explore how the material responded. Immense pressures were required to deform the material, and the pressure required to snap the pasta was greater than for any other known material.

    Earlier simulations had revealed that the outer crust of a neutron star was likewise vastly stronger than steel. But the inner crust, where nuclear pasta lurks, was unexplored territory. “Now, what [the researchers] see is that the inner crust is even stronger,” Providência says.

    Physicists are still aiming to find real-world evidence of nuclear pasta. The new results may provide a glimmer of hope. Neutron stars tend to spin very rapidly, and, as a result, might emit ripples in spacetime called gravitational waves, which scientists could detect at facilities like the Advanced Laser Interferometer Gravitational-wave Observatory, or LIGO. But the spacetime ripples will occur only if a neutron star’s crust is lumpy — meaning that it has “mountains,” or mounds of dense material either on the surface or within the crust.

    “The tricky part is, you need a big mountain,” says physicist Edward Brown of Michigan State University in East Lansing. A stiffer, stronger crust would support larger mountains, which could produce more powerful gravitational waves. But “large” is a relative term. Due to the intense gravity of neutron stars, their mountains would be a far cry from Mount Everest, rising centimeters tall, not kilometers. Previously, scientists didn’t know how large a mountain nuclear pasta could support.

    “That’s where these simulations come in,” Brown says. The results suggest that nuclear pasta could support mountains tens of centimeters tall — big enough that LIGO could spot neutron stars’ gravitational waves. If LIGO caught such signals, scientists could estimate the mountains’ size, and confirm that neutron stars have superstrong materials in their crusts.

    See the full article here .


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  • richardmitnick 11:31 am on August 18, 2018 Permalink | Reply
    Tags: A distant galaxy appears filled with dark matter, , , , , , , Science News   

    From Science News: “A galaxy 11.3 billion light-years away appears filled with dark matter” 

    From Science News

    August 17, 2018
    Lisa Grossman

    LONG AGO AND FAR AWAY Using the telescopes of the Atacama Large Millimeter/submillimeter Array in Chile (shown), astronomers discovered the most distant yet galaxy that appears to be filled with dark matter.

    A distant galaxy appears filled with dark matter.

    The outermost stars in the Cosmic Seagull, a galaxy 11.3 billion light-years away, race too fast to be propelled by the gravity of the galaxy’s gas and stars alone. Instead, they move as if urged on by an invisible force, indicating the hidden presence of dark matter, astrophysicist Verónica Motta of the University of Valparaíso in Chile and her colleagues report August 8 [The Astrophysical Letters].

    “In our nearby universe, you see these halos of dark matter around galaxies like ours,” Motta says. “So we should expect that in the past, that halo was there, too.”

    Motta and her colleagues used radio telescopes at the Atacama Large Millimeter/submillimeter Array (ALMA) to measure the speed of gas across the Cosmic Seagull’s disk, from the center out to about 9,800 light-years. They found that the galaxy’s stars speed up as they get farther from the galaxy’s center.

    That’s a strange setup for most orbiting objects — when planets orbit a star, for instance, the most distant planets move slowest. But it can be explained if the galaxy’s far reaches are dominated by dark matter that speeds things along. Similar measurements of the Milky Way and neighboring galaxies provided one of the first signs that dark matter may exist, although physicists are still trying to detect the proposed particle directly (SN: 2/4/17, p. 15).

    Her team’s finding contrasts with a recent claim that such distant galaxies are oddly lacking in dark matter. That idea comes from a 2017 study by astronomer Reinhard Genzel of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, and his colleagues, who found more than 100 distant galaxies keep their slower stars at the edges and faster stars closer in — little to no dark matter required (SN: 4/15/17, p. 10).

    “In the astrophysical community, the [Genzel] result has been viewed with both excitement and skepticism,” says cosmologist Richard Ellis of University College London, who was not involved in either work. “It makes a lot of sense for others to examine galaxies at these [distances] in different ways.”

    Motta and her colleagues were able to probe dark matter in the most distant galaxy yet, thanks to a massive galactic train wreck called the Bullet Cluster that acted as a huge cosmic telescope.

    M. Markevitch et al/CfA/CXC/NASA (X-ray); D. Clowe et al/U. Ariz./Magellan, ESO WFI, STScI/NASA (lensing map); D. Clowe et al/U. Ariz./Magellan, STScI/NASA (optical)

    The Cosmic Seagull lies behind the Bullet Cluster from Earth’s perspective, and the cluster’s mass distorts the Seagull’s light in a phenomenon called gravitational lensing.

    That distortion earned the disk-shaped galaxy its name — the first images reminded Motta’s team of the seagull logo of a popular music festival in Viña del Mar, Chile. But it also made the galaxy appear magnified by a factor of 50 — a new record.

    “Motta et al have exquisite data,” but their observations are limited, Ellis wrote in an e-mail. The team looked at only one galaxy, and that galaxy is much smaller and less massive than those that seem short on dark matter. Furthermore, the observations don’t cover the entire galactic disk, so the stars may be slower farther out than the team can see.

    Motta agrees that a distant slowdown is possible, although her observations cover the same portion of the galaxy’s disk as the study of galaxies that seem light on dark matter.

    “We are roughly at the place in which we should see the turning point” from fast to slow stars, if it exists, she says. “But we need to extend the study to get that.” Her team has been granted more time with ALMA next year to keep looking.

    See the full article here .


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  • richardmitnick 8:54 am on August 12, 2018 Permalink | Reply
    Tags: , , , , NASA Voyager 1 and 2, , New Horizons may have seen a glow at the solar system’s edge, Science News   

    From Science News: “New Horizons may have seen a glow at the solar system’s edge” 

    From Science News

    August 9, 2018
    Lisa Grossman

    The ultraviolet signal may mark a wall of hydrogen where the sun’s influence wanes.

    HELLO FROM THE OTHER SIDE The sun’s journey through the galaxy may build a wall of hydrogen near the edge of the solar system (curved line to the left of this illustration). The New Horizons spacecraft may have seen evidence of just such a wall. Adler Planetarium/IBEX/NASA

    The New Horizons spacecraft has spotted an ultraviolet glow that seems to emanate from near the edge of the solar system.

    NASA New Horizons spacecraft

    That glow may come from a long-sought wall of hydrogen that represents where the sun’s influence wanes, the New Horizons team reports online August 7 in Geophysical Research Letters.

    “We’re seeing the threshold between being in the solar neighborhood and being in the galaxy,” says team member Leslie Young of the Southwest Research Institute, based in Boulder, Colo.

    Even before New Horizons flew past Pluto in 2015 (SN: 8/8/15, p. 6), the spacecraft was scanning the sky with its ultraviolet telescope to look for signs of the hydrogen wall. As the sun moves through the galaxy, it produces a constant stream of charged particles called the solar wind, which inflates a bubble around the solar system called the heliosphere. Just beyond the edge of that bubble, around 100 times farther from the sun than the Earth, uncharged hydrogen atoms in interstellar space should slow when they collide with solar wind particles. That build-up of hydrogen, or wall, should scatter ultraviolet light in a distinctive way.

    The two Voyager spacecraft saw signs of such light scattering 30 years ago.

    NASA/Voyager 1

    NASA/Voyager 2

    One of those craft has since exited the heliosphere and punched into interstellar space (SN: 10/19/13, p. 19).

    New Horizons is the first spacecraft in a position to double-check the Voyagers’ observations. It scanned the ultraviolet sky seven times from 2007 to 2017, space scientist Randy Gladstone of the Southwest Research Institute in San Antonio and colleagues report. As the spacecraft travelled, it saw the ultraviolet light change in a way that supports the decades-old observations. All three spacecraft saw more ultraviolet light farther from the sun than expected if there is no wall. But the team cautions that the light could also be from an unknown source farther away in the galaxy.

    “It’s really exciting if these data are able to distinguish the hydrogen wall,” says space scientist David McComas of Princeton University, who was not involved in the new work. That could help figure out the shape and variability of the solar system’s boundary (SN: 5/27/17, p. 15).

    After New Horizons flies past the outer solar system object Ultima Thule on New Year’s Day 2019 (SN Online: 3/14/18), the spacecraft will continue to look for the wall about twice each year until the mission’s end, hopefully 10 to 15 years from now, Gladstone says.

    If the ultraviolet light drops off at some point, then New Horizons may have left the wall in its rear view mirror. But if the light never fades, then its source could be farther ahead — coming from somewhere deeper in space, says team member Wayne Pryor of Central Arizona College in Coolidge.

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

  • richardmitnick 9:58 am on June 21, 2018 Permalink | Reply
    Tags: , Science News, Underwater fiber-optic cables could moonlight as earthquake sensors   

    From Science News: “Underwater fiber-optic cables could moonlight as earthquake sensors” 

    From Science News

    June 14, 2018
    Maria Temming

    MOTION OF THE OCEAN FLOOR The network of submarine fiber-optic cables that deliver work emails and cat videos to computers around the world could double as undersea earthquake detectors. Existing cables are shown in purple; planned cables are in blue.

    The global network of seafloor cables may be good for more than ferrying digital communication between continents. These fiber-optic cables could also serve as underwater earthquake detectors, researchers report online June 14 in Science.

    “It’s a very exciting proposition,” says Barbara Romanowicz, a seismologist at the University of California, Berkeley and the Collège de France in Paris.

    Almost all seismic stations around the world are based on land, leaving many oceanic earthquakes undetected. Harnessing the million-plus kilometers of underwater fiber-optic cables to monitor seafloor earthquakes would be “a great step forward” for studying Earth’s interior, Romanowicz says.

    What’s more, quake-detecting cables could bolster tsunami alert systems. “The more [seismic] stations feeding into a tsunami warning system, the faster it can give a warning,” says study coauthor Richard Luckett, a seismologist at the British Geological Survey in Edinburgh.

    To use a telecommunication cable as a seismic sensor, researchers inject light from a laser into one end of the optical fiber and monitor the light that exits the other end. When a seismic wave rattles the cable, it distorts the laser light travelling through it. By comparing the original laser signal with the light that exits the cable, researchers determine how much the beam was distorted along the way — and therefore the strength of the seismic wave that strummed the cable.

    Combining measurements from multiple fiber-optic cables can triangulate the earthquake’s point of origin, explains study coauthor Giuseppe Marra, a frequency metrology researcher at the National Physical Laboratory in Teddington, England. Once researchers know the strength of a seismic wave when it passed the cable and where the wave started, they can determine the original earthquake’s magnitude.

    Submarine seismology

    An underwater fiber-optic cable stretching from Malta to Sicily sensed a magnitude 3.4 quake in the Mediterranean Sea on September 2, 2017. Researchers confirmed this detection with two nearby seismometers. One seismometer near the Malta end of the cable, closer to the earthquake’s epicenter, detected the quake shortly before the cable, and a seismometer near the Sicily end identified it shortly after.


    Marra and colleagues tested their quake-detecting technique on both land-based and submarine fiber-optic cables. One 79-kilometer cable in southern England sensed vibrations from quakes originating in New Zealand and Japan that seismometers put at magnitude 7.9 and 6.9, respectively. Other land-based cables in the United Kingdom and Italy sensed a magnitude 7.3 quake that rocked the Iraq-Iran border last November. And an underwater cable that runs 96 kilometers from Sicily to Malta detected a magnitude 3.4 tremor emanating from the middle of the Mediterranean Sea last September. This seismic sensing technique still needs to be tested on longer cables that cross oceans, Marra says.

    Fiber-optic cables that identify earthquakes far from land could provide new insight into geologic goings-on under the sea. For instance, better views of seafloor movements could help researchers understand how volcanism at mid-ocean ridges creates new oceanic crust, Luckett says (SN: 10/19/13, p. 22). Monitoring seafloor seismic activity could also help scientists study mantle plumes, upwellings of hot, buoyant rock within Earth’s mantle, Romanowicz says (SN: 10/22/11, p. 8).

    See the full article here .


    Please help promote STEM in your local schools.

    Stem Education Coalition

  • richardmitnick 10:14 am on June 20, 2018 Permalink | Reply
    Tags: , , , , Dark fusion?, , , Science News   

    From Science News: “If real, dark fusion could help demystify this physics puzzle” 

    From Science News

    June 6, 2018
    Emily Conover

    DARK CLOUDS Galaxies and galaxy clusters are surrounded by dark matter (illustrated in blue over an image of the cluster Abell 2744; red indicates gas). Dark matter particles may undergo a process called dark fusion, one scientist suggests. XMM-Newton/ESA, WFI/ESO, NASA, CFHT

    Fusion may have a dark side. A shadowy hypothetical process called “dark fusion” could be occurring throughout the cosmos, a new study suggests.

    The standard type of fusion occurs when two atomic nuclei unite to form a new element, releasing energy in the process. “This is why the sun shines,” says physicist Sam McDermott of Fermilab in Batavia, Ill. A similar process — dark fusion — could occur with particles of dark matter, McDermott suggests in a paper published in the June 1, 2018 in Physical Review Letters.

    If the idea is correct, the proposed phenomenon may help physicists resolve a puzzle related to dark matter — a poorly understood substance believed to bulk up the mass of galaxies. Without dark matter, scientists can’t explain how galaxies’ stars move the way they do. But some of the quirks of how dark matter is distributed within galaxy centers remain a mystery.

    Dark matter is thought to be composed of reclusive particles that don’t interact much with ordinary matter — the stuff that makes up stars, planets and living creatures. That introverted nature is what makes the enigmatic particles so hard to detect. But dark matter may not be totally antisocial (SN: 3/3/18, p. 8). “Why wouldn’t the dark matter particles interact with each other? There’s really no good reason to say they wouldn’t,” says physicist Manoj Kaplinghat of the University of California, Irvine.

    Scientists have suggested that dark matter particles might ricochet off one another. But the new study goes a step further, proposing that pairs of dark matter particles could fuse, forming other unknown types of dark matter particles in the process.

    Such dark fusion could help explain why dark matter near the centers of galaxies is more evenly distributed than expected. In computer simulations of galaxy formation, the density of dark matter rises sharply toward a cusp in the center of a galaxy. But in reality, galaxies have a core evenly filled with dark matter.

    Those simulations assume dark matter particles don’t interact with one another. But dark fusion could change how the particles behave, giving them energy that would provide the oomph necessary to escape entrapment in a galaxy’s dense cusp, thereby producing an evenly filled core.

    “You can kick [particles] around through this interaction, so that’s kind of cool,” says physicist Annika Peter of the Ohio State University in Columbus. But, she says, dark fusion might end up kicking the particles out of the galaxy entirely, which wouldn’t mesh with expectations: The particles could escape the halo of dark matter that scientists believe surrounds each galaxy.

    For now, if fusion does have an alter ego, scientists remain in the dark.

    See the full article here .

    Please help promote STEM in your local schools.

    Stem Education Coalition

  • richardmitnick 2:14 pm on June 19, 2018 Permalink | Reply
    Tags: , , , , , Science News   

    From Science News: “Magnetic fields may be propping up the Pillars of Creation” 

    From Science News

    June 15, 2018
    Emily Conover

    The structure’s internal magnetism could mean the columns of gas and dust will be long-lived.

    PILLAR OF STRENGTH Columns of cosmic gas and dust dubbed the Pillars of Creation (shown in this image from the Hubble Space Telescope) may be propped up by an internal magnetic field. NASA, ESA, Hubble Heritage Team/STScI and AURA

    The Pillars of Creation may keep standing tall due to the magnetic field within the star-forming region.

    For the first time, scientists have made a detailed map of the magnetic field inside the pillars, made famous by an iconic 1995 Hubble Space Telescope image (SN Online: 1/6/15). The data reveal that the field runs along the length of each pillar, perpendicular to the magnetic field outside. This configuration may be slowing the destruction of the columns of gas and dust, astronomer Kate Pattle and colleagues suggest in the June 10 Astrophysical Journal Letters.

    Hot ionized gas called plasma surrounds the pillars, located within the Eagle Nebula about 7,000 light-years from Earth. The pressure from that plasma could cause the pillars to pinch in at the middle like an hourglass before breaking up. However, the researchers suggest, the organization of the magnetic field within the pillars could be providing an outward force that resists the plasma’s onslaught, preventing the columns from disintegrating.

    The Pillars of Creation may keep standing tall due to the magnetic field within the star-forming region.

    For the first time, scientists have made a detailed map of the magnetic field inside the pillars, made famous by an iconic 1995 Hubble Space Telescope image (SN Online: 1/6/15). The data reveal that the field runs along the length of each pillar, perpendicular to the magnetic field outside. This configuration may be slowing the destruction of the columns of gas and dust, astronomer Kate Pattle and colleagues suggest in the June 10 Astrophysical Journal Letters.

    FIELD OF DREAMS A map of the magnetic field within the Pillars of Creation reveals that the orientation of the field runs roughly parallel to each skinny column. White bars indicate the field’s orientation in that location. K. Pattle et al/Astrophysical Journal Letters 2018

    Hot ionized gas called plasma surrounds the pillars, located within the Eagle Nebula about 7,000 light-years from Earth. The pressure from that plasma could cause the pillars to pinch in at the middle like an hourglass before breaking up. However, the researchers suggest, the organization of the magnetic field within the pillars could be providing an outward force that resists the plasma’s onslaught, preventing the columns from disintegrating.

    Eagle Nebula NASA/ESA Hubble Public Domain

    The team studied light emitted from the pillars, measuring its polarization — the direction of the wiggling of the light’s electromagnetic waves — using the James Clerk Maxwell Telescope in Hawaii. Dust grains within the pillars are aligned with each other due to the magnetic field. These aligned particles emit polarized light, allowing the researchers to trace the direction of the magnetic field at various spots.

    “There are few clear measurements of the magnetic fields in objects like pillars,” says Koji Sugitani of Nagoya City University in Japan. To fully understand the formation of such objects, more observations are needed, he says.

    Studying objects where stars are born, such as the pillars, could help scientists better understand the role that magnetic fields may play in star formation (SN: 6/9/18, p. 12). “This is really one of the big unanswered questions,” says Pattle, of National Tsing Hua University in Hsinchu, Taiwan. “We just don’t have a very good idea of whether magnetic fields are important and, if they are, what they are doing.”

    See the full article here .

    Please help promote STEM in your local schools.

    Stem Education Coalition

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