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  • richardmitnick 8:39 am on January 9, 2020 Permalink | Reply
    Tags: , , , Bubble-blowing galaxies could help solve a cosmic mystery", , Science News, What’s interesting about the galaxies being together is they can work together as a team.   

    From Science News: “Bubble-blowing galaxies could help solve a cosmic mystery” 

    From Science News

    January 7, 2020
    Christopher Crockett

    Bubbles of ionized hydrogen surround three galaxies (illustrated) in the very early universe, perhaps providing a peek into how most of the hydrogen in the cosmos became ionized. V. Tilvi et al/arXiv.org 2020, NSF’s Optical-Infrared Astronomy Research Lab, KPNO, AURA

    A trio of bubble-blowing galaxies may offer clues about one of the greatest cosmic makeovers in the history of the universe.

    Sometime during the universe’s first billion or so years, most of the hydrogen atoms in the cosmos became ionized when their electrons were torn away (SN: 11/7/19). Astronomers suspect that this reionization — so called because all hydrogen had been previously ionized for the first few hundred thousand years — was triggered by harsh ultraviolet light from the first generations of stars.

    Reionization era and first stars, Caltech

    Now, researchers say they’ve caught a few galaxies blasting out ionizing light and stripping electrons from surrounding hydrogen just 680 million years after the Big Bang. If so, this would be the first direct evidence of a group of galaxies working together to ionize the early cosmos.

    James Rhoads, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Md., presented the results January 5 during a news conference at a meeting of the American Astronomical Society.

    To look for ionizing galaxies, the team sought out galaxies in the remote universe emitting a specific wavelength of ultraviolet light. Neutral hydrogen absorbs this wavelength, preventing it from reaching Earth, but ionized hydrogen lets it slip by. Using the Mayall 4-meter Telescope on Kitt Peak in Arizona, Rhoads and colleagues went hunting for this light in a well-studied strip of the northern sky.

    NOAO/Mayall 4 m telescope at Kitt Peak, Arizona, USA, Altitude 2,120 m (6,960 ft)

    Kitt Peak National Observatory of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O’odham Nation, 88 kilometers 55 mi west-southwest of Tucson, Arizona, Altitude 2,096 m (6,877 ft)

    They found three galaxies, huddled together, shining with the light — light that took over 13 billion years to reach Earth.

    During that long-ago epoch, much of the universe’s hydrogen was still neutral. But the team argues that these three galaxies have created overlapping bubbles of ionized hydrogen in a sea of neutral hydrogen, allowing the ultraviolet light to escape the galaxies unimpeded. The largest of these bubbles is calculated to be over 6 million light-years across, an estimate based on how much ionizing light the brightest galaxy likely pumped out over its lifetime. That’s large enough for the ongoing expansion of the universe to stretch the light out to a longer wavelength during its travel time, so that by the time it reaches the edge of the bubble, it can pass through the enveloping neutral hydrogen (SN: 7/30/19).

    While the brightest of these three galaxies was known to emit ionizing light, no one had yet noticed that its neighbors did as well, says Brant Roberston, an astrophysicist at the University of California, Santa Cruz, who was not involved with this research.

    “What’s interesting about the galaxies being together is they can work together as a team,” Roberston says. “Once the bubbles around them overlap, then it becomes easier for them to start ionizing a larger region around them than if they each had to work on their own in separate little bubbles.”

    These galaxies are so far away from Earth that it’s tough to measure more than a few properties about them, Rhoads says. So it’s hard to say exactly what lets the galaxies send out so much ionizing radiation.

    To grapple with that question, Rhoads and others are looking closer to home. “We’re studying nearby galaxies that are similar in nature to these ones,” he says. By investigating those closer star systems, “we are able to look for trends in what galaxy properties allow ionizing photons to escape.”

    See the full article here .


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  • richardmitnick 7:07 am on January 7, 2020 Permalink | Reply
    Tags: , , Earth's climate, Science News   

    From Science News: “Climate models agree things will get bad. Capturing just how bad is tricky” 

    From Science News

    Carolyn Gramling

    Scientists still aren’t sure what the worst-case scenario for Earth’s future climate looks like.

    Satellites, such as the Joint Polar Satellite System-1 spacecraft illustrated here, track changes on land, in oceans and in the atmosphere. Scientists use these data to verify how well climate models are reproducing real-world conditions. NOAA Satellites

    Earth’s climatic future is uncertain, but the world needs to prepare for change.

    Enter climate simulations, which re-create the physical interactions between land, sea and sky using well-known physical laws and equations. Such models can look into the past and reconstruct ancient ice ages or hothouse worlds with the help of data gleaned from rocks and ice cores.

    But climate scientists also use these simulations to envision a range of different possible futures, particularly in response to climate-altering greenhouse gas emissions. These Choose Your Own Adventure–type scenarios aim to predict what’s to come as a result of different emissions levels over the next few decades. That means putting upper and lower boundaries on answers to questions such as: How hot will it get? How high will the seas rise?

    The good news is that climate simulations are getting better at re-creating even the subtlest aspects of climate change, such as the complicated physics of clouds, the impact of aerosols and the capacity for the ocean to absorb heat from the atmosphere.

    But there’s also bad news: More information doesn’t always mean more clarity. And that is now feeding into uncertainty about just how bad the “worst-case scenario” might be for Earth’s climate.

    Five years ago, the probable worst-case climate scenarios were worrisome enough. Under a so-called “business-as-usual” scenario, in which humankind takes no action to abate greenhouse gas emissions, by 2100 the planet was projected to warm between 2.6 degrees and 4.8 degrees Celsius relative to the average Earth temperature from 1986 to 2005 (SN: 4/13/14). Global mean sea level was thought likely to increase by up to a meter in that same scenario, according to the 2014 report by the Intergovernmental Panel on Climate Change, or IPCC.

    But the newest generation of climate models suggests Earth’s climate may be even more sensitive to very high levels of atmospheric carbon dioxide than once thought. And that, in turn, is increasing projections of just how hot it could get.

    “We’re having discussions of ‘Do we believe these models?’” says Andrew Gettelman, a climate scientist with the National Center for Atmospheric Research, or NCAR, in Boulder, Colo.

    That’s because the simulations use the same equations to look at past and future climate conditions. And many simulations still struggle to re-create accurately the climate of very warm time periods in the past, such as the Eocene Epoch (SN: 11/3/15). As the world gets hotter, it turns out, the uncertainties start to ramp up. “Nobody is arguing about whether [the temperature increase will be] less than 2 degrees,” Gettelman says. “We’re arguing about the high end.”

    Turning up the heat

    The first whiff that something very strange was going on with the latest models came in March, at a meeting in Barcelona of scientists and modelers working on next-gen climate simulations. Many of the simulations are destined to be incorporated into the next IPCC assessment report, the first part of which is scheduled for release in April 2021.

    All of the simulations include estimates of something called equilibrium climate sensitivity, or ECS. That basically means how Earth’s future climate is expected to respond to a new normal — specifically, an atmosphere that contains twice as much carbon dioxide as during preindustrial times.

    A similar trend is shown by several well-known simulations, developed by teams at NCAR, the U.S. Department of Energy, England’s Hadley Centre for Climate Prediction and Research in Exeter and the Paris-based Institut Pierre Simon Laplace, or IPSL. In those models, the ECS was higher, meaning the Earth was more sensitive to carbon dioxide, than in previous model generations. If real, that suggests that the gases can exert even more influence on Earth’s atmosphere than thought. Ultimately, that could mean that temperatures could get hotter than even the highest previous projections suggested.

    In September, scientists with IPSL and the French National Center for Scientific Research, or CNRS, also in Paris, went public with their simulations. Based on projections from two separate climate models, the teams reported that average global warming by 2100 could climb as high as 6 to 7 degrees C (or about 11 to 13 degrees Fahrenheit) relative to preindustrial times.

    Like many new-gen climate simulations, the two French models feature finer-scale resolution and better representations of real-world conditions than past simulations. When tested against present-day climate observations, the new simulations also do a better job of reproducing those observations, says CNRS climatologist Olivier Boucher.

    But the high ECS remains a surprise. “Our [model] is better” in terms of the physics, Boucher says. “But it doesn’t automatically translate into having more confidence for the future projections.”

    This ECS conundrum, which so many of the models still show, came up again November 21 at a meeting of the National Academy of Sciences atmospheric and climate science board in Washington, D.C. The likeliest cause of the high ECS, Gettelman said at the meeting, was in how much the models estimate that clouds will enhance warming (SN: 3/22/14). Among other factors, how high the clouds are in the atmosphere matters: Lower-altitude clouds can reflect sunlight back into space, while higher-altitude clouds can trap heat. Gettelman and his colleagues also discussed the significance of clouds in ECS modeling in July in Geophysical Research Letters.

    “Clouds at high latitudes look like they’re quite important,” Gettelman says. The region over the Southern Ocean is one of particular interest, but there are now studies afoot to examine the effects of high-altitude clouds in the Arctic as well as lower-altitude clouds in the tropics.

    A new paradigm

    Puzzling out how to discuss the high-ECS models will likely be a headache for the authors of the next IPCC report. The landscape of climate simulations is getting more complicated in other ways as well.

    For the 2014 IPCC report, climate modelers also participated in the fifth iteration of a project to set standards and scenarios for climate projections. That project is called the World Climate Research Programme’s Coupled Model Intercomparison Project, or CMIP5 for short.

    CMIP5’s future projections were organized using a concept called “representative concentration pathways,” or RCPs. Each pathway outlined a possible climate future based on the physical effects of greenhouse gases, such as carbon dioxide and methane, as they linger in the atmosphere and trap radiation from the sun. An Earth in which greenhouse gas emissions are dramatically and swiftly curbed was represented by a scenario called RCP 2.6. The business-as-usual scenario was known as RCP 8.5.

    The IPCC’s upcoming sixth assessment report will rely on projections from CMIP6, the new more sensitive models. And in them, RCPs are out, and a new paradigm called “shared socioeconomic pathways,” or SSPs, is in.

    The latest generation of climate models, known collectively as CMIP6 models, include projections that take into account possible socioeconomic changes, as well as how different concentrations of greenhouse gases warm the atmosphere. Those socioeconomic changes include trends in economic growth and technological development, particularly in rapidly growing cities such as Mumbai (shown).akksht/Shutterstock

    While RCP projections are based solely on how different concentrations of gases warm the atmosphere, SSP projections also incorporate societal shifts, such as changes in demographics, urbanization, economic growth and technological development. By tracking how such changes can affect future climate change, scientists hope that SSPs can also help nations better assess how to meet their own emissions target pledged under the Paris Agreement (SN: 12/12/15).

    Data drive

    Human behavior isn’t the only source of uncertainty when it comes to envisioning worst-case scenarios. Scientists also are wrestling with simulating the complicated physical interactions of ice and ocean and atmosphere, particularly as temperatures continue to rise.

    “Most oceans have air on top of them, and [some] oceans have ice on top of them. And the ice is moving, the ice is interacting. It’s a very difficult thing,” says Richard Alley, a glaciologist at Penn State.

    Climate models are just now getting to the point where they can reproduce many of these interactions by “coupling” them together into one simulation, Alley says. Doing so is key to accurately projecting possible futures: Such coupled simulations reveal how these interactions feed into one another, raising the potential for even higher temperatures or even higher seas.

    But numerous sources of possible uncertainty remain when it comes to anticipating the so-called worst-case scenario. For example, how fast the seas will rise is linked to how quickly the great ice sheets blanketing Greenland and Antarctica will lose ice to the ocean, through melting or collapse (SN: 9/25/19).

    Climate simulations are still not reproducing that melting well, even in the IPCC’s special report on climate change’s impacts on ice and oceans released in October 2019. That’s partly because scientists don’t fully understand how the ice responds to climate change, says glaciologist Eric Rignot of the University of California, Irvine. “We’re making progress,” he says, “but we are not there.”

    One of the largest uncertainties is how warming oceans can interact with the vast underbellies of glaciers fringing the ice sheets, eroding them, Rignot says. To identify how such erosion might occur requires detailed bathymetry maps, charts of the seafloor that can reveal deep channels that allow warmer ocean water to sneak into fjords and eat away at the glaciers (SN: 4/3/18). He and his colleagues have been creating some of those maps for Greenland.

    New maps of the bathymetry, or seafloor depth, around Greenland are helping scientists see where warm ocean waters may speed the melting of glaciers. In this region of western Greenland, the pink regions represent the fastest-retreating glaciers. Bathymetry is shown on a scale from deepest (in blue) to shallowest (white).L. An et al/Remote Sensing 2019

    Scientists also are trying to get boots-on-the-ground data to tackle other uncertainties, such as how warming can change the behavior of the ice sheets themselves as they stretch, bend and slide across the ground. In 2018, an international collaboration of scientists began a five-year project to study the breakup of the Florida-sized Thwaites Glacier in the West Antarctic Ice Sheet in real time. Warm ocean waters are thinning the glacier, which supports the ice sheet like a buttress, slowing the flow of ice toward the ocean. Thwaites is likely to collapse, possibly within the next few decades.

    And there are other processes not yet included in the CMIP models that could send ice tumbling rapidly into the sea: Meltwater seeps through cracks and crevasses to the base of the ice sheet, lubricating its slide from land to ocean. Meltwater can also refreeze into solid, impermeable slabs that can speed up the flow of newer meltwater into the ocean (SN: 9/18/19). Perhaps most frighteningly, some researchers have suggested that future warming could cause Antarctica’s giant, steep ice cliffs to suddenly lose large chunks of ice to the ocean, rapidly raising sea levels (SN: 2/6/19).

    There’s a good reason why current climate models don’t include the ice cliff hypothesis, Alley says. “The best models, the ones that you can have the most faith that they’re reconstructing what’s happened recently, generally do not spend a lot of effort on breaking things off,” he says. The problem isn’t in simulating the physics of ice bits breaking off, it’s in simulating exactly which ice shelves will break off — and when. That makes the potential error of simulating those processes very large.

    “That’s a lot of the tension in the community right now,” Alley adds. “How to deal with this is still proving very difficult.”

    The IPCC’s 2019 special report noted the ice cliff hypothesis, but considered it extremely unlikely. But that doesn’t mean it’s impossible, Alley says — or that it hasn’t happened in the past. Evidence from ocean sediments reveals that giant icebergs have broken away from continent-based cliffs and melted out at sea in the past. If Thwaites glacier retreats all the way to Antarctica’s interior, ongoing calving could create massive cliffs twice as high and 10 times as wide as any observed in Greenland, he noted in December at the American Geophysical Union’s annual meeting in San Francisco.

    The IPCC is “assuming we’ll get lucky and it won’t happen,” Alley said. But the ocean sediment data raises “really serious questions about that assumption.”

    Gettelman, meanwhile, cautions that the lingering uncertainty in future projections does not mean the world should wait to see what happens or for scientists to figure it out. “It really means we need to do something soon,” he says. Whether the high temperature or sea level rise projections turn out to be real or not, “it’s still pretty bad.”

    See the full article here .


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  • richardmitnick 9:33 am on January 2, 2020 Permalink | Reply
    Tags: "Injecting a TB vaccine into the blood, , BCG, boosts its effectiveness", , not the skin, Science News   

    From Science News: “Injecting a TB vaccine into the blood, not the skin, boosts its effectiveness” 

    From Science News

    Tara Haelle

    The BCG vaccine is notoriously bad at preventing the most common form of tuberculosis.


    PET-CT scans of rhesus monkey lungs show spots of TB infection and tissue inflammation (red and orange). Monkeys that received a TB vaccine intravenously (bottom) were better protected than those who received it just under the skin (top). University of Pittsburgh School of Medicine.

    Delivering a high dose of a vaccine against tuberculosis intravenously, instead of under the skin, greatly improves the drug’s ability to protect against the deadly disease, a new study finds.

    Changing the typical dose and method of administration of the bacille Calmette-Guérin, or BCG, vaccine prevented TB in 90 percent of rhesus monkeys, researchers report online January 1 in Nature.

    Most “astonishing” is that six of the 10 monkeys who received the IV vaccine never even developed an initial infection when exposed to TB, says Joel Ernst, an immunologist who specializes in TB at the University of California, San Francisco. Preventing infection, not just disease — called sterilizing immunity — is extremely rare with any TB vaccine, says Ernst, who was not involved in the study. Thwarting that infection means that no bacteria can reactivate to cause a latent or active TB infection.

    The BCG vaccine has been around for nearly a century and is the only currently licensed TB vaccine. More than 150 countries, but not the United States, regularly use BCG to protect infants against some forms of TB. But the vaccine often fails to prevent the most common type of tuberculosis infection, in the lungs, in adolescents or adults.

    Globally, TB infected 10 million people in 2018. It kills about 1.5 million a year, making it the most lethal infectious disease. Up to 13 million people in the United States have latent TB infection, which induces an immune response but hasn’t progressed to active tuberculosis. An experimental TB vaccine that could help protect people with the latent infection from developing active TB is in the works (SN: 9/25/18).

    It’s been difficult to create an effective TB vaccine because the bacteria that cause the disease, Mycobacterium tuberculosis, enter cells, where they’re more protected from antibodies, which primarily attack outside cells. Fighting most intracellular infections requires immune cells called T cells to attack the infected cells, says immunologist Robert Seder of the National Institute of Allergy and Infectious Diseases Vaccine Research Center in Bethesda, Md.

    Delivering the BCG vaccine just under the skin causes the body to make some T cells to fight TB. But not enough of these cells are created and get to where they need to be and stay there — the lungs, for example — limiting the vaccine’s effectiveness, says JoAnne Flynn, a microbiologist and immunologist at the University of Pittsburgh’s Center for Vaccine Research.

    A malaria infection similarly requires T cells to fight the malaria parasite inside cells, Seder says. After his success with an intravenous malaria vaccine in another trial [Science], researchers wondered: If they injected BCG vaccine directly into the blood, where it could travel throughout the body, would it trigger the creation of enough T cells in the tissues where the cells need to be?

    Flynn, Seder and their colleagues tested five BCG formulations in macaques: a standard under-the-skin, or intradermal, human dose; a high dose given under the skin (100 times greater concentration than the human dose); an aerosol high dose administered with a mask; an intravenous high dose; and a combination of high-dose aerosol and standard-dose intradermal. Six months later, the research exposed the five differently vaccinated groups of macaques and a sixth unvaccinated control group to TB.

    All of the unvaccinated, standard-dose intradermal and aerosol-vaccinated macaques developed the bacterial infection. The eight macaques that received the intradermal high dose did not have significantly better protection than those that got the standard dose, Flynn says. All but one of those eight developed infection, though two monkeys cleared it several weeks later. In contrast, six of 10 IV-vaccinated macaques never developed a TB infection, and three had fewer than 45 individual TB bacteria in the lungs, a very low amount, and went on to clear the infection.

    One possible reason that the vaccine worked better when given intravenously is the high number of T cells induced by the IV vaccine — 100 times as many in those macaques’ airways compared with the intradermal and aerosol groups. Potentially more important is the discovery that the vaccine induced production of tissue-resident memory T cells [Immunity], primed T cells in the tissue itself, not just the blood.

    Punam Mangtani, an epidemiologist at the London School of Hygiene and Tropical Medicine, calls the research “a rare and exciting proof-of-concept study.”

    Preventing TB in adolescents and adults is crucial, Flynn says, so the major question is whether this approach would be safe and effective in that target population. The only adverse effects seen in the macaques were a temporary, modest increase in inflammation. Ernst says one safety concern is whether intravenous BCG could induce a harmful inflammatory response in people with latent TB infection — about a quarter of the planet’s population. It’s not clear if this vaccine could help or harm those with latent infections, which the researchers plan to test in monkeys. If it could cause harm, screening before vaccination would be necessary.

    For now, the next step is to test how low a dose still offers protection, Flynn says. “This study really provides us hope that a truly effective vaccine against TB is on the horizon,” she says. “I’ve been in the field for 30 years, and I feel we are making progress in really starting to understand the disease and vaccines that can prevent infection.”

    See the full article here .


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  • richardmitnick 8:57 am on December 29, 2019 Permalink | Reply
    Tags: "A chip made with carbon nanotubes not silicon marks a computing milestone", , , Science News   

    From Science News: “A chip made with carbon nanotubes, not silicon, marks a computing milestone” 

    From Science News

    August 28, 2019
    Maria Temming

    The sun may be setting on silicon. Now, computer chips made with carbon nanotubes (one pictured) are the up-and-comers.
    G. Hills et al/Nature 2019

    “Silicon Valley” may soon be a misnomer.

    Inside a new microprocessor, the transistors — tiny electronic switches that collectively perform computations — are made with carbon nanotubes, rather than silicon. By devising techniques to overcome the nanoscale defects that often undermine individual nanotube transistors (SN: 7/19/17), researchers have created the first computer chip that uses thousands of these switches to run programs.

    The prototype, described in the Aug. 29 Nature, is not yet as speedy or as small as commercial silicon devices. But carbon nanotube computer chips may ultimately give rise to a new generation of faster, more energy-efficient electronics.

    This is “a very important milestone in the development of this technology,” says Qing Cao, a materials scientist at the University of Illinois at Urbana-Champaign not involved in the work.

    The heart of every transistor is a semiconductor component, traditionally made of silicon, which can act either like an electrical conductor or an insulator. A transistor’s “on” and “off” states, where current is flowing through the semiconductor or not, encode the 1s and 0s of computer data (SN: 4/2/13). By building leaner, meaner silicon transistors, “we used to get exponential gains in computing every single year,” says Max Shulaker, an electrical engineer at MIT. But “now performance gains have started to level off,” he says. Silicon transistors can’t get much smaller and more efficient than they already are.

    Because carbon nanotubes are almost atomically thin and ferry electricity so well, they make better semiconductors than silicon. In principle, carbon nanotube processors could run three times faster while consuming about one-third of the energy of their silicon predecessors, Shulaker says. But until now, carbon nanotubes have proved too finicky to construct complex computing systems.

    One issue is that, when a network of carbon nanotubes is deposited onto a computer chip wafer, the tubes tend to bunch together in lumps that prevent the transistor from working. It’s “like trying to build a brick patio, with a giant boulder in the middle of it,” Shulaker says. His team solved that problem by spreading nanotubes on a chip, then using vibrations to gently shake unwanted bundles off the layer of nanotubes.

    A new kind of computer chip (array of chips on the wafer pictured above) contains thousands of transistors made with carbon nanotubes, rather than silicon. Although the current prototypes can’t compete with silicon chips for size or speed yet, carbon nanotube-based computing promises to usher in a new era of even faster, more energy-efficient electronics.G. Hills et al/Nature 2019

    Another problem the team faced is that each batch of semiconducting carbon nanotubes contains about 0.01 percent metallic nanotubes. Since metallic nanotubes can’t properly flip between conductive and insulating, these tubes can muddle a transistor’s readout.

    In search of a work-around, Shulaker and colleagues analyzed how badly metallic nanotubes affected different transistor configurations, which perform different kinds of operations on bits of data (SN: 10/9/15). The researchers found that defective nanotubes affected the function of some transistor configurations more than others — similar to the way a missing letter can make some words illegible, but leave others mostly readable. So Shulaker and colleagues carefully designed the circuitry of their microprocessor to avoid transistor configurations that were most confused by metallic nanotube glitches.

    “One of the biggest things that impressed me about this paper was the cleverness of that circuit design,” says Michael Arnold, a materials scientist at the University of Wisconsin–Madison not involved in the work.

    With over 14,000 carbon nanotube transistors, the resulting microprocessor executed a simple program to write the message, “Hello, world!” — the first program that many newbie computer programmers learn to write.

    The newly minted carbon nanotube microprocessor isn’t yet ready to unseat silicon chips as the mainstay of modern electronics. Each one is about a micrometer across, compared with current silicon transistors that are tens of nanometers across. And each carbon nanotube transistor in this prototype can flip on and off about a million times each second, whereas silicon transistors can flicker billions of times per second. That puts these nanotube transistors on par with silicon components produced in the 1980s.

    Shrinking the nanotube transistors would help electricity zip through them with less resistance, allowing the devices to switch on and off more quickly, Arnold says. And aligning the nanotubes in parallel, rather than using a randomly oriented mesh, could also increase the electric current through the transistors to boost processing speed.

    See the full article here .


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  • richardmitnick 6:58 am on December 24, 2019 Permalink | Reply
    Tags: "How 2019’s space missions explored distant worlds", Japan’s Hayabusa2 spacecraft, JAXA’s original Hayabusa spacecraft, , , , , Science News   

    From Science News: “How 2019’s space missions explored distant worlds” 

    From Science News

    Maria Temming

    Planets, asteroids and Arrokoth were the focus of new discoveries.

    Japan’s Hayabusa2 spacecraft, whose shadow is visible in this image, took this photo of the asteroid Ryugu in February after briefly touching down on the asteroid’s surface to collect a sample. The spacecraft is now heading back to Earth.
    JAXA, Univ. of Tokyo, Kochi Univ., Rikkyo Univ., Nagoya Univ., Chiba Inst. Of Technology, Meiji Univ., Univ. of Aizu, AIST

    JAXA/Hayabusa 2 Credit: JAXA/Akihiro Ikeshita

    From asteroids to exoplanets, spacecraft are leaving no space rock unturned. While agencies in China, India and Israel made headlines with missions to the moon, here are some other places that space probes scouted in 2019.

    Zoom and enhance

    Touring Pluto in 2015 may have been New Horizons’ main event (SN: 12/26/15, p. 16), but flying by what used to be called Ultima Thule was an awesome encore.

    WORLD LIKE NO OTHER Long out of reach, Pluto came into focus in 2015 with the NASA/Mew Horizons mission.

    Arrokoth appears as a ruddy deformed snowman in this composite image acquired by NASA’s New Horizons spacecraft as it sped past on January 1, 2019. NASA gave Ultima Thule a new official name, Arrokoth.
    NASA, Johns Hopkins University Applied Physics Laboratory, Southwest Research Institute, Roman Tkachenko

    I spy exoplanets

    NASA’s Transiting Exoplanet Survey Satellite, or TESS, racked up eight exoplanet finds in its first few months of observation (SN: 2/2/19, p. 12).

    NASA/MIT TESS replaced Kepler in search for exoplanets

    That initial cache included some weirdos, such as a planet that is about as dense as pure water and a “lava world” known as LHS 3844b that sizzles at about 540° Celsius. TESS has since discovered a new type of exoplanet called an ultrahot Neptune, which appears to be a fluffy gas giant in the process of stripping down to its rocky core (SN: 8/31/19, p. 11).

    Among the exoplanets discovered by NASA’s Transiting Exoplanet Survey Satellite, TESS, is LHS 3844b (illustrated), a “lava world” slightly bigger than Earth.TESS/NASA and MIT

    Asteroids to go

    The Japan Aerospace Exploration Agency’s Hayabusa2 is expected to become the second spacecraft ever to bring a bit of asteroid back to Earth, after the original Hayabusa probe returned with a souvenir from the asteroid Itokawa in 2010.

    JAXA’s original Hayabusa spacecraft

    Hayabusa2 touched down on the asteroid Ryugu in February to fetch a sample from the asteroid’s surface (SN Online: 2/22/19). Then, to get a deeper sample, Hayabusa2 fired a copper projectile at Ryugu to punch a crater into the asteroid (SN Online: 4/5/19). The probe then ducked down to snag some rubble excavated from the interior (SN: 8/17/19, p. 14). Scientists won’t know exactly how much of Ryugu was collected until Hayabusa2, which started its journey home on November 13, arrives at Earth in late 2020.

    Another sample-return mission, NASA’s OSIRIS-REx, is still orbiting its asteroid.

    NASA OSIRIS-REx Spacecraft

    When the spacecraft first arrived at Bennu in December 2018, observations unveiled a rugged surface littered with boulders — bad news for a probe designed to navigate more beachlike terrain (SN: 4/13/19, p. 10).

    This mosaic image of asteroid Bennu is composed of 12 PolyCam images collected on Dec. 2 by the OSIRIS-REx spacecraft from a range of 15 miles (24 km). The image was obtained at a 50° phase angle between the spacecraft, asteroid and the Sun, and in it, Bennu spans approximately 1,500 pixels in the camera’s field of view.

    Using OSIRIS-REx’s detailed mapping of Bennu from orbit, NASA selected a site for sample collection in the asteroid’s northern hemisphere (SN Online: 12/12/19). Bits of Bennu, to be returned in 2023, may reveal whether a similar asteroid could have delivered to early Earth a molecular starter pack for life (SN: 1/19/19, p. 20).

    The space probe zipped by this Kuiper Belt object, now called Arrokoth, on New Year’s Day (SN Online: 12/30/18).

    Kuiper Belt. Minor Planet Center

    Scientists were on the edge of their seats as the probe snapped pictures and sent higher- and higher-resolution images over several weeks, revealing the visage of Arrokoth to look like an elongated blob, then a snowman and finally a pair of lumpy pancakes (SN: 3/16/19, p. 15). Uncovering the origins of Arrokoth’s awkward shape may lend insight into the early stages of planet formation (SN: 4/13/19, p. 11).

    Meanwhile, on Mars

    NASA’s Mars InSight mission may have made the first recording of a Marsquake. InSight’s seismometer is covered by the domed shield shown here.JPL-Caltech/NASA

    NASA/Mars InSight Lander

    InSight arrived on the Red Planet in November 2018, and the rookie lander may have already captured the first recording of a Marsquake (SN Online: 4/23/19). Unlike tremors on Earth, underground rumblings on Mars are thought to result from the planet contracting as it cools. Studying such seismic signals could help scientists better understand the structure of Mars’ deep interior.

    While InSight had its ear to the ground, the veteran Curiosity rover was measuring the consistency of a Martian mountain (SN Online: 1/31/19).

    NASA/Mars Curiosity Rover

    As Curiosity scaled Mount Sharp, accelerometer readings indicated surprisingly loose rock beneath the rover’s wheels — suggesting that winds formed the mountain by sweeping sediment into a giant pile.

    See the full article here .


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  • richardmitnick 8:31 am on December 19, 2019 Permalink | Reply
    Tags: "These science claims from 2019 could be big deals — if true", Science News   

    From Science News: “These science claims from 2019 could be big deals — if true” 

    From Science News

    December 18, 2019
    Cassie Martin

    Neutron star mergers (the aftermath of one is shown in this illustration) may be a source of short gamma-ray bursts, a team reported in February. O.S. SALAFIA, G. GHIRLANDA, CXC and GSFC/NASA, B. WILLIAMS ET AL

    Discoveries about dinosaurs’ death knell, a watery exoplanet, a new hominid species and more are keeping us on the edge of our seats. But these reports require more proof before they can earn a spot on our list of top stories of the year.

    Dino doomsday

    When an asteroid smashed into Earth about 66 million years ago, it triggered an immense earthquake. A fossil site in North Dakota records the mayhem [PNAS] in the hours after impact, scientists reported in the Proceedings of the National Academy of Sciences. But what’s more tantalizing is what the researchers may have left out of their scientific paper. Robert DePalma, a paleontologist at the University of Kansas in Lawrence and an author on the paper, told the New Yorker that the team found fossilized dinosaurs, pterosaurs and even feathers at the site (SN: 4/27/19, p. 10). Because so few dinosaur fossils from just before the impact have been found, some scientists think that the animals were already dying out. If dinosaur fossils do exist at the site, that’s more evidence that the asteroid impact was to blame.

    Soggy skies

    Water vapor detected in the atmosphere of an exoplanet 110 light-years away from Earth had astronomers saying K2 18b is the first known planet orbiting a distant star that might have liquid water (SN: 10/12/19 & 10/26/19, p. 6). K2 18b might even have water clouds and rain, scientists suggest. Observations with NASA’s James Webb Space Telescope, slated to launch in 2021, could help determine if and how much liquid water, thought to be a key ingredient for life, K2 18b has. But even if the exoplanet is awash in the wet stuff, that doesn’t mean the planet is habitable (SN Online: 10/4/19).

    Exoplanet K2 18b (shown in this artist’s impression) may have liquid water in its atmosphere.M. Kornmesser,NASA/ESA Hubble

    What lies beneath

    A cache of tiny animal carcasses was dredged up from Antarctica’s perpetually ice-covered Lake Mercer, scientists revealed this year. The find was a surprise because this extreme environment was thought to be friendly only for microbes (SN: 2/16/19, p. 11). The limits of habitability may be less narrow than previously thought. But it’s also possible that the remains — including what look like tardigrades, crustaceans, spiders and worms — were carried into the lake by ice or water.

    Hello, Homo luzonensis

    Fossils discovered in a Philippine cave suggest that an unknown hominid species roamed the island now called Luzon at least 50,000 years ago. The proposed new species, dubbed Homo luzonensis, lived around the same time that small hominids wandered the Indonesian island called Flores. The shape and size of some of the fossils match corresponding bones from known Homo species. But the combination of features is unique, researchers say. If confirmed as a separate species, H. luzonensis would be the latest addition to the human evolutionary family tree. The find would also indicate that several Homo groups inhabited East Asia and Southeast Asian islands by the time humans reached southern China, complicating scientists’ view of hominid evolution in Asia (SN: 5/11/19 & 5/25/19, p. 7).

    These fossil teeth belonged to a hominid species that roamed an island in what’s now the Philippines at least 50,000 years ago, scientists say.Callao Cave Archaeology Project

    Stellar jet-setter

    When two neutron stars crashed into each other, as reported in Science News’ top story of 2017 (SN: 12/23/17 & 1/6/18, p. 19), the collision blasted a jet of charged particles into space, new observations suggest (SN: 3/30/19, p. 7). The find supports a theory that mysterious flashes of high-energy light called short gamma-ray bursts are actually jets from neutron star collisions. But researchers will need to observe more of these stellar smashups to figure out if the jets are the norm, or if the 2017 jet was a fluke.

    Sixth sense

    Similar to birds and fish, humans may sense Earth’s magnetic field, a study of brain waves suggests (SN: 4/13/19, p. 6). In lab tests, people displayed a distinct brain wave pattern when exposed to an Earth-strength magnetic field. But the pattern formed only when the field pointed and moved in a certain way. Even if the finding is confirmed, it’s not clear what we would do with this “sixth sense,” or how we would pick up the signal.

    Clearing the way

    Flickering lights and clicks improved memory in mice with signs of Alzheimer’s disease. The light and sounds boosted gamma waves in the brain, which seemed to wipe away disease-related plaques (SN: 4/13/19, p. 9). Mice that received treatment had fewer amyloid-beta plaques in areas of the brain usually hit hard by the disease, plus less of a harmful version of tau protein. Plaque-eating immune cells were kicked into a feeding frenzy, scientists reported. If the treatment works in people (tests are now under way), it would open a new way to target the degenerative disease. But many treatments that have reduced signs of the disease in mice haven’t had the same effect in humans.

    See the full article here .


    Please help promote STEM in your local schools.

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  • richardmitnick 11:40 am on December 5, 2019 Permalink | Reply
    Tags: "A newfound black hole in the Milky Way is weirdly heavy", , , , , Gran Telescopio Canarias, , LAMOST telescope in China, Science News, That’s not just a record- it’s also a conundrum., With a mass of about 68 suns it is far heftier than other stellar-mass black holes (those with masses below about 100 suns) in and around the Milky Way scientists say.   

    From Science News: “A newfound black hole in the Milky Way is weirdly heavy” 

    From Science News

    November 27, 2019
    Christopher Crockett


    A black hole (one illustrated) with a mass equal to about 68 suns has been found in the Milky Way, researchers say. That dark mass is much heavier than other similar black holes. NAOJ

    A heavyweight black hole in our galaxy has some explaining to do.

    With a mass of about 68 suns, it is far heftier than other stellar-mass black holes (those with masses below about 100 suns) in and around the Milky Way, scientists say. That’s not just a record, it’s also a conundrum. According to theory, black holes in our galaxy that form from the explosive deaths of massive stars — as this one likely did — shouldn’t be heavier than about 25 suns.

    The black hole is locked in orbit with a young blue star dubbed LB-1, which sits about 13,800 light-years away in the constellation Gemini, researchers found. Combing through data from the LAMOST telescope in China, Jifeng Liu, an astrophysicist at the Chinese Academy of Sciences in Beijing, and colleagues noticed that LB-1 repeatedly moves toward and away from Earth with great speed — a sign that the star orbits something massive.

    LAMOST telescope located in Xinglong Station, Hebei Province, China

    With additional observations from telescopes in Hawaii and the Canary Islands, the team mapped out the orbit and deduced that the star gets whipped around by a dark mass roughly 68 times as massive as the sun. Only a black hole fits that description, the team reports November 27 in Nature.

    Keck Observatory, operated by Caltech and the University of California, Maunakea, Hawaii, USA.4,207 m (13,802 ft), above sea level,

    Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, Spain, sited on a volcanic peak 2,267 metres (7,438 ft) above sea level

    “I never thought in my wildest dreams you could form a black hole this big [in the Milky Way],” says Michael Zevin, an astrophysicist at Northwestern University in Evanston, Ill. “If the observations pan out to be correct, this is really going to have people scratching their heads.”

    This black hole is not the heftiest in the Milky Way. That title goes to the behemoth in the center of the galaxy, a supermassive black hole in a class all its own with a mass of over 4 million suns. The mass of LB-1’s black hole is, however, on par with some of the black holes discovered recently by gravitational wave detectors, which sense ripples in spacetime from (among other things) merging pairs of black holes (SN: 2/17/16).

    But those black holes formed in far-off galaxies, probably in environments with a relative dearth of elements heavier than helium. The star LB-1 has a richer inventory of those elements, and presumably the star that formed its partner black hole had a similar stock. Stars with a greater abundance of heavy elements lose more of their mass to stellar winds, as those elements present a larger target to the radiation that drives those winds. Massive stars that form black holes also eject a lot of their mass during the supernova explosions that end their lives.

    “These two processes make very small black holes even out of very massive stars,” Liu says. But the black hole near LB-1 apparently didn’t get that memo.

    To make a black hole of 68 solar masses requires a reduction in the mass lost to stellar winds by a factor of five, Liu says. “We don’t know whether this is possible theoretically.”

    Alternatively, the black hole might have emerged from a failed supernova, an attempted stellar explosion that doesn’t have quite enough energy to hurl the star’s guts into space, leaving the gas to fall back into the black hole.

    The team also wonders if the black hole is the work of two stars. The scenario is speculative, Liu says, and “the odds are slim.” But in this story, LB-1 once orbited a snuggled-up pair of heftier stars that died and left behind two cores that merged into one black hole.

    It’s also possible that what appears to be a single 68-solar-mass black hole is actually two lighter black holes locked in a tight embrace. Such a pair would periodically nudge LB-1, giving it a subtle rocking motion that Liu and colleagues are searching for with other telescopes.

    Before getting caught up in potential origin stories, the observations need to be double-checked, Zevin cautions. “I wouldn’t put money down that it’s a definitive detection yet,” he says.

    The one catch, which the researchers do note, is that the calculated mass of the black hole depends on getting the distance to LB-1 correct. Their derived distance of 13,800 light-years — based on the star’s apparent brightness and calculations of its intrinsic luminosity — is about twice as far as the distance to the star determined by the Gaia satellite, a multiyear mission to create a precise 3-D map of over 1 billion stars in the Milky Way (SN: 5/9/18). If the Gaia distance is correct, then the black hole might be only 10 times as massive as the sun. (If the star is closer, then it’s less luminous, so less massive. That would mean that a lighter black hole is needed to explain the speed at which the star is getting whipped around.)

    That’s not necessarily a strike against the study. The researchers note that a much lower luminosity for the star would be at odds with its measured temperature. And if LB-1 is wobbling around a black hole, that would throw off the accuracy of the Gaia data, says Zevin. “But it is an important point that needs to be worked out.”

    See the full article here .


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  • richardmitnick 3:55 pm on November 26, 2019 Permalink | Reply
    Tags: "19 more galaxies mysteriously missing dark matter have been found", , , , , Science News   

    From Science News: “19 more galaxies mysteriously missing dark matter have been found” 

    From Science News

    November 25, 2019
    Christopher Crockett

    Most dwarf galaxies, like NGC 5477 seen in this image from the Hubble Space Telescope, have far more dark matter than normal everyday matter. But researchers recently found 19 dwarf galaxies that seem to be missing huge stores of dark matter. NASA/ESA Hubble

    A smattering of small galaxies appear to be missing a whole lot of dark matter.

    Most of a typical galaxy is invisible. This elusive mass, known as dark matter, seems to be an indispensable ingredient for creating a galaxy — it’s the scaffolding that attracts normal matter — yet reveals itself only as an extra gravitational tug on gas and stars.

    But now, researchers have found 19 dwarf galaxies — all much smaller than the Milky Way — that defy this common wisdom. These newly identified outliers have much less dark matter than expected. The finding, published November 25 in Nature Astronomy, more than quintuples the known population of dark-matter renegades, adding fuel to an already simmering mystery.

    “We are not sure why and how these galaxies form,” says Qi Guo, an astrophysicist at the Chinese Academy of Sciences in Beijing. Typical dwarf galaxies concentrate dark matter far more than their larger cousins, she notes. Their smaller size leads to weaker gravity, which has trouble holding on to tenuous clouds of gas. That usually shifts the balance of mass in dwarf galaxies away from normal matter and toward dark matter.

    “This new class of galaxy is straining our ability to explain all galaxies in one cohesive framework,” says Kyle Oman, an astrophysicist at Durham University in England who was not involved in this research.

    In 2016, Oman and his colleagues identified two galaxies that appeared to be missing dark matter. In short order, two more oddballs turned up (SN: 3/28/18).

    Guo and her colleagues wondered if these galaxies had more company. So using existing data from the Arecibo radio telescope in Puerto Rico, the team weighed dwarf galaxies by looking at how fast hydrogen whipped around each one. Higher speed means more total mass. The researchers then combined the mass of the hydrogen and of all the stars, inferred from starlight, to estimate how much of each galaxy’s mass is made up of normal matter.

    For every galaxy, total mass added up to more than the mass of the gas and stars — not surprising, as that extra mass is the dark matter. But in about 6 percent of cases, there wasn’t as much extra mass as expected.

    One oddball, designated AGC 213086, weighs in at around 14 billion suns. If it were typical, about 2 percent of its mass — nearly 280 million solar masses — would be gas and stars. Instead, its actual inventory of normal matter is about 3.8 billion solar masses, or about 27 percent of its total mass.

    Of 324 dwarf galaxies analyzed, 19 appear to be missing similarly large stores of dark matter. Those 19 are all within about 500 million light-years of Earth, and five are in or near other groups of galaxies. In those cases, the researchers note, perhaps their galactic neighbors have somehow siphoned off their dark matter. But the remaining 14 are far from other galaxies. Either these oddballs were born different, or some internal machinations such as exploding stars have upset their balance of dark matter and everyday matter, or baryons.

    It may not be a case of missing dark matter, says James Bullock, an astrophysicist at the University of California, Irvine. Instead, maybe these dwarf galaxies have clung to their normal matter — or even stolen some — and so “have too many baryons.” Either way, he says, “this is telling us something about the diversity of galaxy formation…. Exactly what that’s telling us, that’s the trick.”

    See the full article here .


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  • richardmitnick 9:25 am on November 17, 2019 Permalink | Reply
    Tags: "Realigning magnetic fields may drive the sun’s spiky plasma tendrils", Science News,   

    From Science News: “Realigning magnetic fields may drive the sun’s spiky plasma tendrils” 

    From Science News

    November 14, 2019
    Christopher Crockett


    Whiskery plasma jets, known as spicules, on the sun appear as dark, threadlike structures in this image, acquired at the Goode Solar Telescope in Big Bear, Calif. T. Samanta, GST & SDO

    The Goode Solar Telescope pointed at the Sun in the morning.
    Date 23 July 201
    Big Bear Solar Observatory
    Location Big Bear Lake, California, US
    Altitude 2,060 m (6,760 ft)


    Tendrils of plasma near the surface of the sun emerge from realignments of magnetic fields and pump heat into the corona, the sun’s tenuous outer atmosphere, a study suggests.

    The new observation, described in the Nov. 15 Science, could help crack the century-plus mystery of where these plasma whiskers, called spicules, come from and what role — if any — they play in heating the corona to millions of degrees Celsius.

    Spicules undulate like a wind-whipped field of wheat in the chromosphere, the layer of hot gas atop the sun’s surface. These plasma filaments stretch for thousands of kilometers and last for just minutes, shuttling ionized gas into the corona. Astronomers have long debated how spicules form — with the sun’s turbulent magnetic field being a prime suspect — and whether they can help explain why the corona is a few hundred times as hot as the sun’s surface (SN: 8/20/17).

    To look for connections between spicules and magnetic activity, solar physicist Tanmoy Samanta of Peking University in Beijing and colleagues pointed the Goode Solar Telescope, at Big Bear Solar Observatory in California, at the sun. They snapped images of spicules forming, while also measuring the surrounding magnetic field. The team discovered that thickets of spicules frequently emerged within minutes after pockets of the local magnetic field reversed course and pointed in the opposite direction from the prevailing field in the area.

    Counterpointing magnetic fields create a tension that gets resolved when the fields break and realign, and the team postulates that the energy released in this “magnetic reconnection” creates the spicules. “The magnetic field energy is converted to kinetic and thermal energy,” says study coauthor Hui Tian, a solar physicist also at Peking University. “The kinetic energy is in the form of fast plasma motion — jets, or spicules.”

    To see if this energy made it into the corona, the team pored through images acquired at the same time by NASA’s orbiting Solar Dynamics Observatory. Those data revealed a glow from charged iron atoms directly over the spicules. That glow, Tian says, means the plasma reached roughly 1 million degrees Celsius. Whether that’s enough to sustain the scorching temperature throughout the corona, however, remains to be seen.

    “Their observations are amazing,” says Juan Martínez-Sykora, a solar physicist at the Lockheed Martin Solar & Astrophysics Laboratory in Palo Alto, Calif.

    Capturing this level of detail is difficult, Martínez-Sykora says, because individual spicules are relatively small and come and go so quickly. He does caution, though, that the magnetic reconnection story needs to be checked with computer simulations or more observations. As it stands, it remains a postulation, he says.

    See the full article here .


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  • richardmitnick 11:26 am on November 10, 2019 Permalink | Reply
    Tags: , By watching how atoms behave when they’re suspended in midair rather than in free fall physicists have come up with a new way to measure Earth’s gravity., , Physicists split atoms into a weird quantum state called superposition — where one version of the atom is slightly higher than the other., , , Science News   

    From Science News: “Trapping atoms in a laser beam offers a new way to measure gravity” 

    From Science News

    November 7, 2019
    Maria Temming

    The technique can measure slight gravitational variations, which could help in mapping terrain.

    A new type of experiment to measure the strength of gravity uses atoms suspended in laser light (with the machinery pictured above), rather than free-falling atoms. V. Xu.

    By watching how atoms behave when they’re suspended in midair, rather than in free fall, physicists have come up with a new way to measure Earth’s gravity.

    Traditionally, scientists have measured gravity’s influence on atoms by tracking how fast atoms tumble down tall chutes. Such experiments can help test Einstein’s theory of gravity and precisely measure fundamental constants (SN: 4/12/18). But the meters-long tubes used in free-fall experiments can be unwieldy and difficult to shield from environmental interference such as stray magnetic fields. With a new tabletop setup, physicists can gauge the strength of Earth’s gravity by monitoring atoms suspended a couple millimeters in the air by laser light.

    This redesign, described in the Nov. 8 Science, could better probe the gravitational forces exerted by small objects. The technique also could be used to measure slight gravitational variations at different places in the world, which may help in mapping the seafloor or finding oil and minerals underground (SN: 2/12/08).

    Physicist Victoria Xu and colleagues at the University of California, Berkeley began by launching a cloud of cesium atoms into the air and using flashes of light to split each atom into a superposition state. In this weird quantum limbo, each atom exists in two places at once: one version of the atom hovering a few micrometers higher than the other. Xu’s team then trapped these split cesium atoms in midair with light from a laser.

    Got you, atom. To measure gravity, physicists split atoms into a weird quantum state called superposition — where one version of the atom is slightly higher than the other (blue dots connected by vertical yellow bands in this illustration). The researchers trap these atoms in midair using laser light (horizontal blue bands). While held in the light, each version of a single atom behaves slightly differently, due to their different positions in Earth’s gravitational field. Measuring those differences allows physicists to determine the strength of Earth’s gravity at that location.

    Measuring the strength of gravity with atoms that are held in place, rather than being tugged downward by a gravitational field, requires tapping into the atoms’ wave-particle duality (SN: 11/5/10). That quantum effect means that, much as light waves can act like particles called photons, atoms can act like waves. And for each cesium atom caught in superposition, the higher version of the atom wave undulates a little faster than its lower counterpart, due to the atoms’ slightly different positions in Earth’s gravitational field. By tracking how fast the waviness of the two versions of an atom gets out of sync, physicists can calculate the strength of Earth’s gravity at that spot.

    “Very impressive,” says physicist Alan Jamison of MIT. To him, one big promise of the new technique is more controlled measurements. “It’s quite a challenge to work on these drop experiments, where you have a 10-meter-long tower,” he says. “Magnetic fields are hard to shield, and the environment produces them all over the place — all the electrical systems in your building, and so forth. Working in a smaller volume makes it easier to avoid those environmental noises.”

    More compact equipment can also measure shorter-range gravity effects, says study coauthor Holger Müller. “Let’s say you don’t want to measure the gravity of the entire Earth, but you want to measure the gravity of a small thing, such as a marble,” he says. “We just need to put the marble close to our atoms [and hold it there]. In a traditional free-fall setup, the atoms would spend a very short time close to our marble — milliseconds — and we would get much less signal.”

    Physicist Kai Bongs of the University of Birmingham in England imagines using the new kind of atomic gravimeter to investigate the nature of dark matter or test a fundamental facet of Einstein’s theory of gravity called the equivalence principle (SN: 4/28/17). Many unified theories of physics proposed to reconcile quantum mechanics and Einstein’s theory of gravity — which are incompatible — violate the equivalence principle in some way. “So looking for violations might guide us to the grand unified theory,” he says. “That’s one of the Holy Grails in physics.”

    See the full article here .


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