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  • richardmitnick 5:11 pm on November 13, 2020 Permalink | Reply
    Tags: "US Takes an Important Step Toward Quantum Internet", A new kind of computing needs a new kind of internet., , , Inside Science, Quantum bits- or qubits- from two distant quantum computers can be entangled in a third location., , Stony Brook University, , The actual quantum internet is going to be a collection of solid-state-based quantum computers like the ones in Chicago and atomic-based quantum computers like the ones we have here in New York., The last obstacle is far more distant in a future where the New York quantum network is connected to the one being built by Argonne National Laboratory and the University of Chicago., The recent experiment is essentially half of a quantum repeater., The researchers did it over standard internet cables., This reliance on traditional internet means that the endeavor to build a quantum internet is very interdisciplinary., We have to find a way to connect all of them to really come out with a first prototype of the quantum internet., You cannot build a quantum network and be successful without a classical network., You have to control manage and synchronize the quantum devices over the classical network to really transmit information between the two ends of a quantum network.   

    From Inside Science: “US Takes an Important Step Toward Quantum Internet” 

    From Inside Science

    November 12, 2020
    Meredith Fore

    A recent experiment has created a one-way quantum network between two labs, reaching a milestone on the path to creating a quantum internet.

    1
    Credit: Dmitriy Rybin via Shutterstock.

    While researchers continue to make quantum computers increasingly capable, regular computers still hold a massive advantage: Their data, represented in sequences of zeros and ones, can ride the information superhighway. Quantum computers, which instead run on quantum superpositions of zeros and ones, can’t use the internet to communicate with each other.

    Multiple projects across the world are working to create a “quantum internet,” a network where quantum computers can share and exchange information. One such project, a collaboration between Brookhaven National Lab and Stony Brook University in New York, recently hit a major milestone: demonstrating that quantum bits, or qubits, from two distant quantum computers can be entangled in a third location.

    This is a critical step in creating a quantum internet, and significantly, the researchers did it over standard internet cables.

    “Part of the challenge of building a quantum internet is, to what extent can I even get quantum information through the kinds of fiber networks that we use for normal communications?” said Joseph Lykken, deputy director of research at Fermi National Accelerator Laboratory and head of the Fermilab Quantum Institute. “That’s really important, and they’re doing this at a longer distance at Brookhaven-Stony Brook than I think almost anybody else.”

    A new kind of computing needs a new kind of internet.

    Quantum computers aren’t superpowerful versions of classical computers. Instead, they approach computing in a whole new way. They can theoretically take advantage of quantum mechanical concepts such as superposition and entanglement to solve certain types of problems — for example, ones that show up when encrypting data or simulating chemical reactions — much faster than traditional approaches. Quantum computing technology is still in the early stages of development, and many of the most promising applications remain unrealized. Other applications may have yet to be discovered.

    Similarly, the “quantum internet” will not be a superfast and secure version of today’s internet. Instead, it will likely have particular applications transferring quantum information between computers. To do this, the computers’ qubits are entangled, meaning they are put in a superposition in which their separate possible quantum states become dependent on each other and the qubits then become a single quantum system. Measuring the state of one of these qubits breaks the superposition, immediately influencing the state of the others — and this measurement/entanglement process is how quantum information can be transmitted.

    Entanglement between two quantum computers has been experimentally possible for several years, but the team at Brookhaven and Stony Brook has gone one step further: They have created the longest quantum network in the United States by showing that two quantum computers can be entangled using a third node. This is the first step in building a network where many computers can “talk” to each other through a central node.

    To do the experiment, the researchers faced a challenge unique to quantum systems: In order to entangle quantum particles, which make up qubits, the particles must arrive at the node completely indistinguishable from one another even though they took different paths to get there. The more different the path, the more difficult this is — and the network between Brookhaven and Stony Brook runs over traditional fiber-optic cables that are miles long, going under the neighborhoods and highways of Long Island.

    “It’s not really feasible to lay new cables everywhere, so being able to use what’s in the ground was important,” said Kerstin Kleese Van Dam, the director of Brookhaven’s Computational Science Initiative.

    Any unexpected interaction between one of the transmitted quantum particles and its environment might have made it distinguishable from the other. But despite all the potential sources of interference, the experiment was able to prove that the particles could travel over 70 kilometers (almost 45 miles) over traditional infrastructure and still arrive indistinguishable.

    “Our results demonstrate that these photons can be entangled, that the measurement will work,” said Eden Figueroa, a quantum physicist at Stony Brook University and lead scientist of the project.

    The recent experiment was one-way: The quantum computers sent their qubits to the node, but the node simply determined whether they could be entangled and didn’t send anything back. The next step, Figueroa said, is to entangle the computers’ quantum memories, which would be analogous to linking two traditional computers’ hard drives.

    “Down the line we hope that instead of just memories, we will be entangling computers — not just connecting the hard drives but also the processing units,” Figueroa said. “Of course, that’s not easy.”

    How far away is the quantum internet?

    The remaining obstacles to a quantum internet are a blend of research questions and infrastructure concerns. One issue is that manipulating qubits between quantum computers requires synchronization and supervision in a way that the management of traditional bits doesn’t. This means that while quantum computers can’t directly exchange quantum information over the internet, they still need conventional computers that do use the internet to communicate.

    “You cannot build a quantum network and be successful without a classical network,” said Inder Monga, the director of the Energy Sciences Network, which provides networking services to all U.S. national labs. “You have to control, manage and synchronize the quantum devices over the classical network to really transmit information between the two ends of a quantum network.”

    This reliance on traditional internet means that the endeavor to build a quantum internet is very interdisciplinary, Monga and Figueroa said. It requires expertise in basic quantum computing research as well as communication infrastructure engineering.

    “There are as many research problems as are engineering problems,” Monga said, “and to really get to the vision of the quantum internet, it will require a strong collaboration between people and funding to solve not just the basic physics research problems but also the really grand engineering challenges as well.”

    A central obstacle to the quantum internet is what Figueroa calls “the holy grail of quantum communication”: a quantum repeater. A quantum repeater works like an amplifier, in that it receives a signal of quantum information and passes it on so that entanglement between computers can happen at a greater distance. This is necessary to make a quantum internet that spreads beyond Long Island. But there’s a catch: Any interaction with a qubit breaks its superposition — and for information to be transmitted, that can’t happen until the qubit reaches its destination. A true quantum repeater would be able to amplify a qubit without interacting with it, a seemingly paradoxical task.

    The recent experiment is essentially half of a quantum repeater. Kleese Van Dam and Figueroa see a completed quantum repeater in the near future: possibly as soon as 2022, Figueroa said. They plan to transmit entanglement to a third lab in Brooklyn but need a quantum repeater to do so.

    “We hope that in a few years, we might actually have a working system with repeaters,” Figueroa said. “The minute we can demonstrate that quantum repeater connection, you just need to reproduce the same architecture, again and again, to connect places that are more and more distant from each other.” He sees a network across New York state in 10-15 years.

    The last obstacle is far more distant, in a future where the New York quantum network is connected to the one being built by Argonne National Laboratory and the University of Chicago, or the one being built in Europe. Those networks are built using fundamentally different quantum computers — while the New York network uses computers whose qubits are embedded in single trapped atoms, the other networks use what are called solid-state systems to make and manipulate qubits. The two kinds of quantum computers perform computation with completely different architecture.

    “You can imagine that the actual quantum internet is going to be a collection of solid-state-based quantum computers like the ones in Chicago and atomic-based quantum computers like the ones we have here, and we have to find a way to connect all of them to really come out with a first prototype of the quantum internet,” Figueroa said. “That would be very cool. That would be like science fiction.”

    In July 2020, the U.S. Department of Energy released a “blueprint” of their strategy to create a national quantum internet. This effort includes the Brookhaven-Stony Brook project and the Argonne-University of Chicago project, which are in turn both supported by research at other national labs such as Fermi National Accelerator Laboratory, and Lawrence Berkeley, Oak Ridge, and Los Alamos National Laboratories.

    “While quantum computing has gotten a lot of press and funding, the wave is going toward quantum networking,” Figueroa said, “because unless you connect quantum computers into this quantum internet, their applications will be limited. So, it is a good time to be doing these kinds of experiments.”

    See the full article here .

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  • richardmitnick 3:54 pm on January 29, 2020 Permalink | Reply
    Tags: CBR, , , , , How standard are "standard candles"?, , Inside Science, Solid experimental evidence but unsatisfying theories,   

    From FNAL via Inside Science: “Dark Energy Skeptics Raise Concerns, But Remain Outnumbered” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    via

    Inside Science

    January 24, 2020
    Ramin Skibba

    Some scientists have been poking at the foundations of dark energy, but many say the concept remains on solid, if mysterious, ground.

    2
    Spiral galaxy NGC 5714. In 2003, a faint supernova (not visible in this later picture) appeared about 8000 light-years below the central bulge of NGC 5714. European Space Agency via Flickr. CC BY 2.0

    Since the dawn of the universe, the biggest stars have ended their lives with a bang, blowing out their outer layers in bright, fiery bursts that can be seen many light-years away. Astronomers use these supernova explosions like marks on an expanding balloon to measure how fast the universe is growing.

    Based on studies of dozens of supernova explosions, astronomers in the late 1990s realized that the universe’s expansion seems to be accelerating. They hypothesized that some unseen “energy,” which works the opposite of gravity, was pushing everything outward. The concept of so-called dark energy quickly became popular, and ultimately, scientists’ consensus view. It earned three physicists the 2011 Nobel Prize.

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

    Recently, however, some scientists have been poking at this foundation of dark energy research.

    A team of Korean scientists published findings on Jan. 5 questioning the reliability of using supernovae to measure intergalactic distances. This followed a paper published in November [Astronomy and Astrophysics] that also cast doubt on the supernova evidence from a different angle, arguing that our galactic neighborhood is flowing in a particular direction, affecting certain kinds of distance measurements.

    In both instances, other scientists pushed back, noting potential flaws in the methodology and conclusions of the new studies.

    While most scientists still seem to believe that dark energy remains on solid ground, no one yet has any firm idea what it actually is.

    How standard are “standard candles”?

    Standard Candles to measure age and distance of the universe from supernovae. NASA

    Every time a star goes supernova, its radiant explosion follows such a familiar pattern that scientists nicknamed them “standard candles.” Assuming supernovae are predictable that way, astronomers can estimate how far away they are mainly based on how bright they appear. They can then map the universe’s expansion history by studying supernova both nearby and far away — that is, both recent and from a long time ago.

    It’s like gauging how far away vehicles are at night by looking at their headlights. If you made incorrect assumptions about what kinds of vehicles they are — for example assuming they are trucks with bright lights a long distance away when they are in fact smaller vehicles much closer — then your data and your inferences about the length of the road would be skewed.

    Young-Wook Lee, an astronomer at Yonsei University in South Korea and lead author of the Jan. 5 study, and his colleagues question a common and important assumption in the standard candle approach: that the brightness or luminosity of supernova explosions don’t vary when you look further back into the universe’s past.

    To test their hypothesis, they studied supernova in galaxies whose stars’ ages had been precisely measured and found that the brightness of a supernova depends on the ages of its host galaxy’s stellar population. The stars that produce supernovae are generally younger, further in the universe’s past, which is problematic for physicists estimating the universe’s expansion rate.

    “Supernova luminosity should vary as a function of cosmic time, and that hasn’t been accounted for in the so-called ‘discovery’ of dark energy,” said Lee.

    But to Dragan Huterer, an astrophysicist at the University of Michigan in Ann Arbor, the data from the paper doesn’t warrant a sweeping reconsideration of dark energy.

    “These evolution effects have not been observed to be strong, and cosmologists partly take them into account,” Huterer argued. He conceded there may be a small correlation, but not one large enough to shake the foundation of dark energy’s consensus. “I’d bet my life on it,” he said.

    Joshua Frieman, a Fermilab astrophysicist, thinks Lee and his team are doing legitimate research, but is also skeptical about whether one could draw sweeping conclusions from it. He points out that the study’s findings show only a weak trend with age; they use a model that estimates ages of a few supernova older than the universe’s age; and they focus only on a small sample of elliptical galaxies, while the scope of supernova studies that support dark energy include all kinds of galaxies.

    Solid experimental evidence, but unsatisfying theories

    While many scientists argue against overinterpreting results that seem to question the foundations of dark energy, both of the recent papers fall into accepted lines of research. Supernova cosmology has for years been plagued by questions about systematic uncertainties infecting every step of calculations, including how their fluxes and light curves are measured and calibrated. Researchers need to account for every factor, no matter how small, that could muddy a study of the expanding universe. And there’s always a concern for something missed, an unknown unknown.

    Such concerns are actually evidence of a well-developed field, argued Tamara Davis, an astrophysicist at the University of Queensland in Australia. “Once a field becomes very mature, the tiny details that were negligible before become more important,” said Davis. A focus on myriad uncertainties that affect a measurement by just a percent or two is actually a sign that the measurement’s quite good already, she argued.

    Astronomers’ current controversy over the precise value of the Hubble constant, which describes how fast the universe is expanding, reflects a similarly mature field, she said. (This question about the exact expansion rate is different than the one about whether the rate’s accelerating.) That research, similar to supernova cosmology, has made great strides since the 1990s, and now small, previously ignored discrepancies come to the fore.

    Most scientists Inside Science interviewed feel dark energy is still on solid ground. Even if Lee’s study and others like it discredited the kinds of supernova cosmology findings that formed the groundwork for dark energy research, other kinds of research now also point toward dark energy, Frieman argued. This includes studies of fluctuations in the cosmic microwave background [CMB] radiation — radiation [CBR] that’s thought to be left over from soon after the Big Bang and which bears an imprint of the growing universe when it was young — and studies of the large-scale structure of the universe, involving surveys of hundreds of thousands of galaxies over a wide area.

    CMB per ESA/Planck

    CBR per ESA/Planck

    “Yes, in 1998, you could’ve said, ‘There are supernova systematic uncertainties, so maybe the universe isn’t accelerating,'” Frieman said. “But in 2020, we now have multiple pieces of evidence that the stool holding up dark energy is much more stable, so you could knock out supernova and still say we have strong evidence for cosmic acceleration from these other probes.”

    Current and upcoming experiments could add yet more precision to studies of dark energy. These include the Dark Energy Survey, the Dark Energy Spectroscopic Instrument, space-based missions, and the newly renamed Vera Rubin Observatory, being built in northern Chile. But theoretical physicists are behind, Huterer said, as they still don’t have a compelling explanation for what dark energy is and where it came from.

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Timeline of the Inflationary Universe WMAP

    The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

    DES is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

    Over six years (2013-2019), the DES collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.

    LBNL/DESI spectroscopic instrument on the Mayall 4-meter telescope at Kitt Peak National Observatory starting in 2018

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

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

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

    Coma cluster via NASA/ESA Hubble

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


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


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

    The LSST, or Large Synoptic Survey Telescope renamed named the Vera C. Rubin Observatory by an act of the U.S. Congress.

    LSST telescope, The Vera Rubin Survey Telescope currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    LSST Data Journey, Illustration by Sandbox Studio, Chicago with Ana Kova

    “I think the precision on dark energy parameters is definitely going to be improving with these missions,” Frieman said. The data so far is consistent with the idea of dark energy as a simple cosmological constant, a ubiquitous vacuum energy somehow produced by the universe’s expansion that generates yet more expansion. But Frieman hopes new data may reveal something more exotic, such as a mysterious substance called quintessence, which some scientists have proposed could explain the accelerating expansion of the universe. Which theory will be ahead 10 years from now “is anyone’s guess,” Freiman said.

    See the full here.


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    FNAL Icon

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 8:36 am on April 2, 2018 Permalink | Reply
    Tags: , How Far Can Laser Light Travel?, Inside Science, ,   

    From Inside Science: “How Far Can Laser Light Travel?” 

    Inside Science

    1
    Image credits: Abigail Malate, Staff Illustrator

    March 30, 2018
    Yuen Yiu

    Have you ever played with a pocket-sized laser, wondering how far its light would travel? Could you, a naughty student inside a classroom on Earth, annoy a poor substitute teacher on Mars by waggling your laser pointer at him?​

    T​he short answer: no. By the time the light finally reached Mars, the glint would be a million times dimmer than the faintest light visible to the human eye.

    But you don’t need to take our word for it. The math needed to calculate the answer is surprisingly simple.

    Partly inspired by a talk at a recent astronomy meeting that explored whether we could detect photons from potential exoplanet-dwelling aliens, Inside Science performed some of our own calculations to see if a hypothetical alien Galileo could observe photons coming from Earth.

    All we need is an equation for calculating how quickly a laser beam spreads out as it travels through space. From that we can use straightforward geometry to derive the diameter of the beam when it hits its target. Finally, we divide the power output of the laser by the area of the final lit spot and voila! — that’s how intense the laser is at the destination. While the way humans, or aliens, perceive the brightness of this light is much less straightforward, for the purpose of this exercise we treat brightness and light intensity as the same thing.

    ______________________________________________________________________________________
    The math:

    One only needs three rather simple equations for all the calculations done in this article. First, if we assume the laser is optimized so that its spreading angle is at its theoretical minimum, then we can calculate its beam divergence (in radians) using this equation.

    (The laser’s wavelength)/(π × The laser’s aperture)

    Then a little bit of geometry will give us the size of the final lit spot at the destination.

    π × (Beam divergence in radians × Distance)2

    Finally, the brightness at the destination is given by dividing the output power of the laser over the area of the spot.

    (The laser’s power)/(Size of the spot)

    If you didn’t make a mistake in your calculations and kept everything in radians, watts and meters, the final number should be in watts per square meter.

    The dimmest light visible to the naked eye in perfect darkness is around one ten-billionth of a watt per square meter. However, with the presence of urban light pollution, one usually can’t see stars much dimmer than the North Star, which has an intensity of around four-billionths of a watt per square meter. For comparison, the full moon is almost a million times brighter at one-thousandth of a watt per square meter. Finally, the midday sun is at a whopping 1,000 watts per square meter, about half a million times brighter than the moon.

    In this article, we will be using these numbers as references.
    ______________________________________________________________________________________

    Your pocket laser pointer

    The power for an average laser pointer is a measly 0.005 watts. However, because of the narrow path of the laser beam, if you pointed it directly at your eye from an arm’s length away, the little illuminated dot on your eyeball would be 30 times brighter than the midday sun. So, don’t do this at home, or anywhere.

    Still, the narrow beam will spread out over long distances. Around 100 meters away from a red laser pointer, its beam is about 100 times wider and looks as bright as a 100-watt light bulb from 3 feet away. Viewed from an airplane 40,000 feet in the air — assuming there’s no clouds or smog — the pointer would be as bright as a quarter moon. From the International Space Station, it would fade to roughly as bright as the brightest star in the night sky — Sirius.

    For Starman, the dummy driving the Tesla car that Elon Musk’s company Space X recently launched into space, your little red laser pointer would be too dim to notice. If you want to get his attention, you’ll need something brighter.

    The Navy’s missile-killer

    The U.S. Navy might have what we need. According to recent reports [Military Balance Blog], their current goal is to develop a laser that is both logistically practical and powerful enough to destroy incoming cruise missiles. A laser like that would need to put out about 500,000 watts of power — 100 million times more powerful than your pocket laser pointer. These lasers typically operate in the infrared spectrum, which is invisible to humans. But for the sake of this exercise we’ll assume that both Starman and the Martians can see in the infrared.

    Weapons-grade lasers also tend to have a much larger opening, or aperture, which counterintuitively causes the laser beam to spread out less, thus enhancing the beam’s ability to maintain its intensity over longer distances.

    Because of the larger aperture, if the missile-killer laser beam is aimed at the moon, the infrared spot it would make on the surface would only be about 1.5 miles across. For comparison, the incredibly dim red dot from your pocket laser pointer would be 8 miles wide once it reached the moon.

    If you could see in the infrared and stood on the moon underneath the military laser’s beam, it would appear roughly 30 times brighter than the full Earth. That’s quite bright, but not blindingly so. It’s still only one-thousandth the brightness of the midday sun on Earth.

    By the time the beam reached the Martians — if we assume the shortest possible distance between Earth and the red planet, which is about 34 million miles — the spotlight would be about 200 miles across. Its light should still be noticeable — about half as bright as the brightest star in the sky sans the sun — but not exactly attention grabbing.

    Looks like we need more power.

    The most powerful laser ever built

    Several scientific facilities around the world have huge lasers that operate at more than a thousand trillion watts. In other words, these lasers have as much power as a million trillion pocket laser pointers — that’s almost a billion laser pointers for every person on the planet!

    3
    One of the acceleration beams of the LFEX laser in Osaka. Credit: Osaka University


    National Ignition Facility at LLNL


    The National Ignition Facility has followed up on its March firing with yet-another record, flicking the switch on a pulse that topped 500 trillion watts and 1.85 megajoules of UV laser. Richard Chirgwin 16 Jul 2012

    If run continuously, these lasers would use up the entire world’s electricity supply in seconds. Luckily, the only reason these lasers can put out such intense power is that they concentrate the release over an extremely short period of time — usually less than a trillionth of a second. The extremely short laser pulse is then focused down to a point a few thousandths of a millimeter across, and can be 10 trillion trillion times brighter than the surface of our sun. It’s so powerful that scientists are using them to rip apart empty space itself in a quest to learn more about the fundamental laws of our universe.

    What if we just want to use this for fun and shoot it at space invaders? One major drawback is that these lasers usually produce ultraviolet light, which is mostly absorbed by the Earth’s atmosphere. If we don’t want to turn our air into plasma, we’d have to construct our building-sized super laser cannon in space instead.

    For the extremely brief time we could afford to fire the laser at Mars, it would cast UV light a thousand times more intense than the midday sun on Earth over an area 150 miles across. Let’s hope that the Martians have some SPF-1,000 sunblock handy.

    Sadly, as we know by now, there are no little green men on Mars, or most likely anywhere else in our solar system. However, there are thousands of discovered exoplanets — planets that orbit around stars outside our solar system — many of which have the possibility to contain life. What if we try to get their attention?

    Proxima Centauri, located roughly four light-years away, is the closest star to us and is orbited by several exoplanets. If we aimed our most powerful laser there, by the time the light reached it, it would appear brighter than the brightest star looks to us in a clear night sky. So, four years after we’ve fired our laser, if there’s any alien astronomer looking at the right spot in their night sky, they may notice a nanosecond flash of ultraviolet light and go, “What was that?”

    Yuen would like to thank Eric Korpela, an astronomer from the Berkeley SETI Research Center for the insightful conversation that led to this exercise. This article is partly inspired by a presentation by Barry Welsh, an astronomer from the University of California, Berkeley, during the 231st meeting of the American Astronomical Society, and also this blog post from What If?by Randall Munroe.

    See the full article here .

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  • richardmitnick 6:03 pm on July 3, 2017 Permalink | Reply
    Tags: Delbrück scattering, Inside Science, , , Polarized gamma rays, , , The future Extreme Light Infrastructure in Măgurele Romania, Vacuum studies, Werner Heisenberg's Uncertainty Principle   

    From Inside Science via Don Lincoln at FNAL: “A Study About Nothing” 

    Inside Science

    June 29, 2017
    Yuen Yiu

    1
    Image credits: Abigail Malate

    Scientists find new ways to measure the infinitesimally small fluctuations that exist in a vacuum.

    A vacuum is a space absolutely devoid of matter, at least according to the Merriam-Webster dictionary. But if you talk to a physicist you may get a different answer. According to quantum physics, even vacuums are not completely empty. Constant fluctuations in energy can spontaneously create mass not just out of thin air, but out of absolutely nothing at all.

    “It’s like a boiling sea of appearing and disappearing particle pairs,” said James Koga, a theoretical physicist from the National Institutes for Quantum and Radiological Science and Technology in Kyoto, Japan. The pairs, made up of one particle and one antiparticle, exist for only moments. Koga is investigating the subtle effects caused by these fluctuations.

    This peculiar nature of vacuum, sometimes referred to as “quantum vacuum,” is not just theoretical speculation. It has real, measurable effects on our physical reality. Although these effects are usually far too small to impact even the most sensitive instruments of today, scientists think the picture will change for the miniaturized technologies of tomorrow.

    “In the macroscopic world, we don’t care about these forces at all. You wouldn’t care about it when you are driving a car for instance. It’s totally negligible,” said Alejandro Manjavacas, a physicist specializing in photonics at the University of New Mexico in Albuquerque. “But in the context of nanotechnology or nanophotonics — at a super small scale, these effects will start playing a role.”

    Although the concept of a fluctuating vacuum was theorized and proven during the first half of the last century, scientists are still grappling with the implications. Two recently published papers explore two separate aspects of the same mystery — what happens when there is nothing at all?

    A glistening ocean

    The energy fluctuation in vacuum can be explained by the uncertainty principle of quantum physics. The principle, first introduced by German physicist Werner Heisenberg, states that at any definite point in space, there must exist temporary changes in energy over time. Sometimes this energy is converted into mass, generating particle-antiparticle pairs.

    Most of the time these newly born pairs recombine and vanish before interacting with anything. Because of this, physicists like to refer to these pairs as “virtual particles,” but this doesn’t mean they aren’t real — they just need something to interact with to make their presence felt.

    For this, Koga and his team envision a way to observe this boiling sea of vacuum the same way we see glistening waves in the ocean — with light. In their latest paper, published in Physical Review Letters, they lay down the theoretical groundwork needed for the experiment. Specifically, they want to study photons that bounce off an atomic nucleus in a distinctive way that wouldn’t happen without the “boiling” vacuum acting as the middleman. This peculiar light phenomenon is known as Delbrück scattering, predicted by German-American physicist Max Delbrück in 1933. The effect was later observed experimentally in 1975 — but just barely.

    “[Scientists] could kind of guess that the Delbrück scattering was there, but it was like if you include this effect in your calculation then it agrees more with the data,” said Koga.

    Koga and his team hope to take Delbrück scattering to another level by characterizing the phenomenon’s effect. It is as if scientists knew about air resistance, but still needed to study it further so that engineers could use the knowledge to build an airplane.

    The task is tricky. To measure Delbrück scattering, one must shine light onto trillions of atomic nuclei, which creates a problem. Photons bounce off nuclei, electrons and even each other in all directions, via all kinds of different interactions. How can one distinguish which photon is scattered from what?

    Koga’s team suggests that we use polarized gamma rays. Just like polarized sunglasses can help you see better by filtering out unwanted solar glares, polarized gamma rays can help scientists sift through the gazillions of photons based on their polarization, in addition to energy and scattered angle. As long as one knows where to look for the specific photons that are the results of Delbrück scattering, one should be able to pick them out from the lineup.

    “The point that we are trying to make in our paper is by using a new polarized source, you can almost see the signal isolated,” said Koga.

    But there is just one problem — such an instrument doesn’t exist. At least not yet.

    Enter the future Extreme Light Infrastructure in Măgurele, Romania. This facility will not only provide the polarized gamma rays Koga proposed, but will make some of the brightest gamma rays in the world. This is important because just like a brighter ambient light can shorten the exposure time for taking a photo, a brighter gamma ray can shorten the run time for Koga’s proposed experiment.


    Credit: ELI-NP Romania

    Kazuo Tanaka, the scientific director of the Nuclear Physics division of the future facility, is pleased with Koga’s team’s proposal.

    “I think their proposal is very crystal clear. They calculated how many days of shooting they need for the experiment, and came up with 76 days,” he said. “I think if they do the experiment we can have a very definitive measurement for Delbrück scattering.”

    While the facility is still under construction, and will not be ready for the experiment at least until 2019, a different group of physicists are studying the same nothingness of vacuum, but with a different set of eyes. Instead of beaming light into the vacuum and looking for a glint, physicist Alejandro Manjavacas and his group at the University of New Mexico want to know if the fluctuations of vacuum can actually exert an invisible force on physical objects — as if they were being moved by Jedis.


    The video shows two plates moving towards each other in a vibrating pool of water, an analogy to the Casimir effect that exist in a fluctuating vacuum. Credit: Denysbondar

    The Casimir effect, named after Dutch physicist Henrik Casimir, describes the force that pushes two objects together due to surrounding waves. The effect exists for two beads on a vibrating string, or two boats in a wavy ocean, as well as two particles in a fluctuating vacuum. Much like Delbrück scattering, the Casimir effect was theorized in 1948 and has already been confirmed, in 1996. So, what is left to be discovered?

    “Most of the work that was done on Casimir effect was for systems that weren’t moving, or if they were moving, they were moving in a uniform motion,” said Manjavacas.

    In a paper published in Physical Review Letters, Manjavacas and his colleagues calculated how the Casimir effect can nudge objects that are already spinning and moving. Through calculations, they discovered that when a tiny sphere spins near a flat surface, it will move as if it is rolling down the surface, despite never making contact with it.

    “If you try to make a nanostructure that involves moving parts that are very close together, it is crucial to know what is going to be the effect from these type of forces. You’ll need to know whether it is going to cause the moving parts to get stuck,” said Manjavacas. “Or we can use these forces to our advantage, such as using them to move objects or to force them to do the things that we want.”

    In their study, the researchers evaluated the effect for spheres with diameters ranging from 50 to 500 nanometers, much less than one hundredth the width of a human hair. As expected, the relationship between the spinning and the lateral movement isn’t straightforward — it depends on the speed that the sphere is spinning, as well as the size of the sphere and the distance between the sphere and the surface. These minute effects may soon be relevant on the frontier of technology, for example when engineers design medical nanobots.

    2
    Virtual Particles and Black Holes
    The sidebar image shows a simulated animation of a black hole moving across a galaxy in the background. Credit: Wikicommons/CC BY-SA 3.0
    Even though the quantum interpretation of vacuum — complete with strange particles popping into and out of existence — accurately describes our reality, how can we tell that this isn’t just another placeholder theory? Will the theory eventually fail just like the geocentric model, or the flat earth model, or perhaps most relevantly, the famous failed theory of ether from the 19th century?
    The theory of ether was proposed by physicists to explain how light waves can propagate through the vacuum of space. Based on intuition, scientists back then believed that a medium was necessary for light waves to travel, just like the waves in the ocean travel through the medium of water. This hypothesis was disproved in 1887 by Albert Michelson and Edward Morley, in a famous experiment, in which they measured the speed of light in perpendicular directions and found no difference. Albert Michelson was later awarded a Nobel Prize in 1907 for his achievements, and became the first Nobel laureate from the United States.

    So, will the quantum model of vacuum also be proved wrong? Most physicists today do not think so. In fact, Nobel laureate Robert Laughlin from Stanford University has written in his book “A Different Universe: Reinventing Physics from the Bottom Down” specifically about this comparison: “The word [ether] has extremely negative connotations in theoretical physics because of its past association with opposition to relativity. This is unfortunate because, stripped of these connotations, it

    Beyond its impact on nanotechnologies and particle accelerators here on earth, the fluctuating vacuum extends its effects into space. In 1968, British astrophysicist Stephen Hawking predicted that when a particle-antiparticle pair is created on the edge of a black hole’s event horizon, the pair can be pried apart by gravity — one particle falling into the black hole and the other escaping. The escape of one of the particles then contributes to an infinitesimally small, and so far purely theoretical, radiation known as Hawking radiation.
    Hawking radiation, if proven, will play a crucial role in determining the lifetime of black holes. However, even if the radiation is real, it will still be far too faint for us to detect it. There have been a few analogous models that can successfully reproduce the phenomenon in a laboratory setting, but they use light waves or sound waves instead of gravitational waves of black holes. There is hope that the Large Hadron Collider near Geneva, Switzerland, with a higher energy output, can create a super tiny black hole that lasts but a split second, and offer a more definitive answer on Hawking radiation. But for now, no direct observation for Hawking radiation has been possible, leading to some saying that the “jury is still out.”
    “This is a pity, because if they had, I would have got a Nobel prize,” said Hawking during a 2008 lecture.

    A real virtuality

    Even though the quantum interpretation of vacuum — complete with strange particles popping into and out of existence — accurately describes our reality, how can we tell that this isn’t just another placeholder theory? Will the theory eventually fail just like the geocentric model, or the flat earth model, or perhaps most relevantly, the famous failed theory of ether from the 19th century?

    The theory of ether was proposed by physicists to explain how light waves can propagate through the vacuum of space. Based on intuition, scientists back then believed that a medium was necessary for light waves to travel, just like the waves in the ocean travel through the medium of water. This hypothesis was disproved in 1887 by Albert Michelson and Edward Morley, in a famous experiment, in which they measured the speed of light in perpendicular directions and found no difference. Albert Michelson was later awarded a Nobel Prize in 1907 for his achievements, and became the first Nobel laureate from the United States.

    So, will the quantum model of vacuum also be proved wrong? Most physicists today do not think so. In fact, Nobel laureate Robert Laughlin from Stanford University has written in his book “A Different Universe: Reinventing Physics from the Bottom Down” specifically about this comparison: “The word [ether] has extremely negative connotations in theoretical physics because of its past association with opposition to relativity. This is unfortunate because, stripped of these connotations, it rather nicely captures the way most physicists actually think about the vacuum.”

    Because unlike the ether theory, the quantum model of vacuum, with all its fluctuations and peculiar features, has since been thoroughly tested and proven.

    “We see pair creation all the time actually, like in particle accelerators,” said Koga. In fact, it happens so often that for certain experiments scientists actually have to consider the phenomenon as “noise” that could obscure the signal they are looking for, according to Koga.

    “We now have experimental evidence of all kinds of particles coming in and out [of the vacuum],” said Toshiki Tajima, a physicist from the University of California, Irvine. “Muons and anti-muons, protons and anti-protons, and even quarks and anti-quarks.”

    In 1665, Robert Hooke and Antoni van Leeuwenhoek discovered microbes when they pointed their microscopes at “nothing.” In 1964, Arno Penzias and Robert Woodrow Wilson discovered the cosmic microwave background when they pointed their telescopes at “nothing.” Vacuum is perhaps the ultimate “nothing,” so if history is any indication, “nothing” is an interesting place, especially if you want to look for something.

    See the full article here .

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  • richardmitnick 6:06 pm on May 22, 2017 Permalink | Reply
    Tags: , , , , , Inside Science, Meet the Biggest Censor of All: the Universe,   

    From AIP via Inside Science: “Meet the Biggest Censor of All: the Universe” 

    AIP Publishing Bloc

    American Institute of Physics

    1

    Inside Science

    Theoretical physicists contemplate the seemingly impossible situation of a point in space-time where gravity goes to infinity.

    2
    Image credits: Animated image by Yuen Yiu, Staff Writer (Source image, credit: Ute Kraus) Rights information: CC BY-SA 2.5

    May 18, 2017
    Yuen Yiu

    What exists inside black holes? Wormholes? Entire universes? The back of a bookcase ? Since nothing can communicate from inside a black hole to the outside world, we may never know for sure. But even if astrophysicists can’t directly see what’s going on behind the curtains of black holes, they can still make guesses.

    One particular item of interest is the concept of a gravitational singularity — a hypothetical point in space-time where gravity would go to infinity. Even though Albert Einstein’s theory of general relativity predicts the existence of singularities inside black holes, it can’t describe what actually happens at those points. This gap in our understanding of the universe is like a plot hole where a writer introduces a monster in the first chapter, but somehow can’t describe what the monster does at all — it’s a Chekhov’s gun that leaves us all hanging.

    Research in astrophysics is often limited by the amount of data that scientists can gather from space. Oftentimes that is simply because we can’t build instruments powerful enough to detect these events in our universe, but other times the information we want to gather is guarded by the laws of physics. For instance, any information that exists within the event horizon of a black hole simply cannot escape the black hole’s gravitational pull and reach us, no matter how much better our telescopes can get. In order to try making sense of it all, theoretical physicists are using a multitude of complex mathematical tools to explore what exactly happens in the strange and well-hidden areas of the universe.

    A mathematical conundrum posited by Einstein

    “Einstein’s equations [of general relativity] predict that singularities will form under certain circumstances — places where the equations break down, and the gravitational fields become infinite,” said Toby Crisford, a doctoral student in theoretical physics at the University of Cambridge in England.

    If a gravitational singularity existed near Earth, the deterministic nature of our laws of physics would break down. Then, literally anything could happen — a black hole appearing out of nowhere, time flowing backwards or even the sun transforming to become the head of a baby. Since this doesn’t make sense — even though it is allowed by Einstein’s theory of general relativity — scientists are trying to come up with explanations that can reconcile the concept of singularities with Einstein’s equations, and of course, with reality.

    One leading conjecture to remedy this conundrum is known as cosmic censorship. Proposed in 1969 by famous British theoretical physicist Roger Penrose, the conjecture argues that no singularities — except that of the Big Bang — can be observed from the rest of space-time. Therefore, Penrose believes that if singularities existed in our universe, they would always be sealed inside black holes, or as he calls it — cosmically censored.

    If this is true, then even if singularities existed, their effects would be confined to within the black holes that house them, where other exotic physics such as the yet-to-be understood quantum gravity can take over, and the plot hole introduced by Einstein’s equations will finally be patched up, more than 100 years since its creation.

    While most scientists are fairly confident that the conjecture is true — since we haven’t yet detected a singularity — definitive proof remains at large, nearly 50 years since Penrose first questioned Einstein’s predictions. Since an experimental approach is almost impossible, physicists have been looking into theoretical scenarios in which so-called naked singularities could defy the conjecture, within universes with all kinds of weird dimensionalities or space-time curvatures that are different from our own.

    A naked singularity, uncensored

    “There have been counter examples to the cosmic censorship conjecture in higher dimensions,” said Crisford, such as the five dimensional ring black holes that theorists modeled to explore specific scenarios where naked singularities could sit unmasked in space-time, without a surrounding black hole.

    According to Ivan Agullo, a theoretical physicist from Louisiana State University in Baton Rouge, calculations about singularities are often so difficult that theorists can only look for solutions in certain set ups, such as space-time with a specific curvature or even in different dimensions. This is similar to how physicists often leave out certain variables when estimating the path of a projectile, because exact solutions can be extremely complicated if all variables are to be considered, such as aerodynamics, variations in gravity or even the Coriolis effect.

    “What we can do is to accumulate knowledge, by testing these arguments in scenarios where the equations are actually solvable,” Agullo said.

    The latest paper by Crisford’s group, published May 2 in the journal Physical Review Letters, takes a new approach to the problem. It presents a counterexample to Penrose’s conjecture, but in four dimensions — three of space and one of time. It is the first time anyone has mathematically constructed a naked singularity within a 4-D space-time. However, the negatively curved space-time they used in their calculations — known as anti-de Sitter space — is still quite different from our 4-D reality, and the curvature of space-time itself also remains a hotly debated topic.

    “But I guess [our calculation] is one step closer to reality,” Crisford said.

    Other researchers are taking a different approach that looks beyond what’s ordinarily prescribed in Einstein’s general relativity equations.

    A mysterious quantum dress

    An international collaboration among theoretical physicists from Brazil, Italy and Chile looked into the effects generated at the quantum level by the matter surrounding singularities. Their paper, published in March, also in Physical Review Letters, claims that these quantum effects can create the event horizon that shields an otherwise naked singularity from outside observers, even when the naked singularity exists as a solution to the classical Einstein equations.

    First, they began with a model where a rotating naked singularity exists in three-dimensional space-time — two in space and one in time. They discovered that as soon as the model was modified to include additional quantum effects, an event horizon formed around the singularity — or a “quantum dress,” as they called it [Science Direct].

    They also looked into a different scenario, where they started the model with a rotating black hole right off the bat. In this case, they found the inclusion of quantum effects led to an instability inside the black hole. This instability, they suspect, might be able to preserve the laws of physics that would otherwise stop making sense, or more specifically, the predictability of the physics inside the black hole. While quantum effects seem like a blanket term for many different physical phenomena, here the key effect at play is a concept conceived by Stephen Hawking in 1974, known as Hawking radiation.

    “A perhaps cartoonish way of understanding Hawking radiation, is that according to quantum physics, even if in vacuum, there’re constantly particles and anti-particles being created,” said Marc Casals, one of the authors of the paper and a theoretical physicist at the Brazilian Center for Research in Physics in Rio de Janeiro. “When this happens near a black hole, one of them can fall into the black hole, and the other one can escape, and it’ll look like the black hole is emitting out radiation.”

    In extreme situations, effects that seem negligible can become significant, just like how special relativity explains why the clocks on board GPS satellites slow down at high orbital speeds. Unless you live on a space station they won’t affect the watch on your wrist nearly as much.

    Similarly, scientists believe that Hawking radiation, though rooted in tiny quantum effects, plays a very important role in the physics of black holes. Even though this all sounds highly theoretical and technical, experimentalists are actively trying to directly observe these effects here on Earth. You might have heard the claim that scientists at the Large Hadron Collider in Europe might create a scary microscopic black hole here on Earth. This led to minor hysteria from members of the public who feared a doomsday scenario where the black hole would devour the planet. In that specific scenario, Hawking radiation is the key effect that will cause the tiny black hole to disintegrate within a tiny fraction of a second, way before any damage could be done.

    To quantum and beyond

    Studies of black holes, naked singularities and other exotic phenomenon could help researchers understand what is often the most difficult of the four fundamental forces to grasp: gravity. Gravity is by far the weakest force, and its close tie to general relativity definitely doesn’t make it any easier to understand. While all the other three forces — weak, strong and electromagnetic — have been unified under quantum field theory, gravity remains stranded by itself, as the last elusive piece in the search for a “theory of everything.”

    “We know that general relativity is not a complete theory of everything,” Crisford said.

    Within the Big Bang and black holes lie the keys scientists need to fully understand gravity. However, the same gravity that makes black holes interesting also prevents us from looking into them — by creating event horizons that make up the black holes in the first place. The concepts of singularities and cosmic censorship, tangled up with the rest of these mysteries, represent holes in the incomplete puzzle for the “theory of everything.” Will physicists ever find the missing pieces? Nobody knows for sure.

    One way scientists are advancing the quest is with quantum gravity, a field still in its relative infancy. A complete theory of gravity, which quantum gravity might provide, would not only tell us what happens at the center of black holes, but also likely fill in the plot holes in the current understanding of the universe.

    “In order to tackle cosmic censorship completely, ultimately we will need to understand quantum gravity,” said Agullo. “But it’s a very difficult topic.”

    See the full article here .

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    AIP Building

    AIP serves a federation of physical science societies in a common mission to promote physics and allied fields.

     
  • richardmitnick 4:39 pm on January 18, 2017 Permalink | Reply
    Tags: , , , , , , Inside Science   

    From Dark Energy Survey via Inside Science: “Computer Science Technique Helps Astronomers Explore the Universe” 

    Dark Energy Icon

    The Dark Energy Survey

    1

    Inside Science

    “Deep learning” finds telltale arcs of light that indicate massive objects.

    2
    Image credits: Abigail Malate, Staff Illustrator

    January 13, 2017
    Ramin Skibba

    Google uses “deep learning” to generate captions for images, Facebook uses it to recognize faces and Tesla uses it to train self-driving cars. Now astronomers have caught on to deep learning, a form of machine learning in which a computer can be trained to identify or classify particular objects in images.

    The newest telescopes, such as the Dark Energy Survey, which uses a 4-meter telescope in northern Chile and covers about one quarter of the southern sky, take millions of images of a variety of celestial objects. These often include visual distortions, cosmic rays and satellite trails that make them difficult to interpret. Deep learning could help process this deluge of data quickly.

    “Astronomy is the next frontier to take it on,” said Brian Nord, an astrophysicist at Fermilab [FNAL] in Batavia, Illinois.

    Nord is one of a group of astrophysicists who search for rare gravitational lenses with signs of curved slivers of light or duplicated images that indicate the presence of massive objects skewing light rays.

    Gravitational Lensing NASA/ESA
    Gravitational Lensing NASA/ESA
    Gravitational microlensing, S. Liebes, Physical Review B, 133 (1964): 835
    Gravitational microlensing, S. Liebes, Physical Review B, 133 (1964): 835

    The scientists often have to sift through numerous images by eye, one at a time. But now they have a potentially game-changing technique at their disposal.

    Massive objects in space — like clusters of galaxies combined with dark matter hidden from view — distort the light we see from faraway galaxies and quasars, deflecting and warping the light rays around them. Distant galaxies look like magnified arcs, as if seen through the edge of a cosmic magnifying glass.

    Scientists have found hundreds of such lenses so far, confirming predictions of general relativity theory by Albert Einstein and others in the 1930s. With newly developed deep learning tools, astronomers expect to find at least 2,000 more with the Dark Energy Survey, according to research presented by Nord at the American Astronomical Society meeting in Grapevine, Texas on Jan. 4. A big catalog of gravitational lenses would help astronomers learn more about the nature of dark matter and how it holds galaxies together.

    Finding gravitational lenses is like finding needles in haystacks far away, when no two needles or haystacks are alike. “Deep learning is a way for us to create a model of a complicated system,” Nord said.

    To make complex classifications, astronomers have long used statistical machine learning techniques like neural networks, which are programmed systems with layered nodes connected in a web, much like neurons in the human brain. Deep learning just involves more interconnected layers or steps in the computation, including “hidden” ones of increasing complexity as the algorithm proceeds from input to output.

    For example, with facial recognition software, someone feeds in an image, and the system first detects edges, lines and curves. Intermediate layers then put together higher-level features, like eyes or a mouth, and eventually a face. For gravitational lenses, the software would gradually recognize a big galaxy surrounded by arcs, indicating lensed background objects.

    After it’s been trained with many lens images, such an algorithm can then find new lenses in images it has never encountered before. The current state-of-the-art algorithms can correctly identify these lenses all but a few percent of the time, when they mistake a particularly messy image for the real thing.

    “If it works but is 97 percent accurate, you could be vastly swamped by false positives,” said Colin Jacobs, who along with Karl Glazebrook at Swinburne University of Technology in Melbourne, Australia, is also working on the problem. “Ideally, it should be more accurate than what you’d need for computer vision or facial recognition,” he added.

    To address this challenge, Nord and Jacobs and their colleagues could design the algorithm to be strict, ensuring that it finds the cream of the crop, the clearest lenses in a survey. But this risks missing many lenses. Alternatively, they are trying to be more lenient in their search criteria, knowing it would mean later weeding out by hand some images that happen to look a bit like lenses.

    Over the past couple years, astronomers have begun to apply deep learning in other areas as well, mostly for deciphering images in other ways. They have used the techniques to distinguish between distant galaxies and stars in the Milky Way, to estimate the distance to faraway objects and to categorize the structures of galaxies, which can take on a variety of spiral and elliptical shapes.

    Others have utilized citizen science, recruiting people around the world to help sort through images. A project called Galaxy Zoo, for example, has classified the structures of hundreds of thousands of galaxies, while another, called Space Warps, has discovered dozens of candidate gravitational lenses missed by others.

    Nord applauds these efforts, but if his software works as well as advertised, “deep learning has the potential to be much faster,” he said.

    See the full article here .

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    DECam, built at FNAL
    DECam, built at FNAL
    CTIO Victor M Blanco 4m Telescope
    CTIO Victor M Blanco 4m Telescope interior
    CTIO Victor M Blanco Telescope at Cerro Tololo which houses the DECAm

    The Dark Energy Survey (DES) is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 120 scientists from 23 institutions in the United States, Spain, the United Kingdom, Brazil, and Germany are working on the project. This collaboration [has built] an extremely sensitive 570-Megapixel digital camera, DECam, and [has mounted] it on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory high in the Chilean Andes. Started in Sept. 2012 and continuing for five years, DES will survey a large swath of the southern sky out to vast distances in order to provide new clues to this most fundamental of questions.

     
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