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  • richardmitnick 8:15 am on November 4, 2016 Permalink | Reply
    Tags: , , CMB research, , , Here's What The Big Bang's Leftovers Tell Us About The Universe Today   

    From SLAC: “Here’s What The Big Bang’s Leftovers Tell Us About The Universe Today” 

    Nov 3, 2016
    Ethan Siegel

    1
    The fluctuations in the CMB give rise to the Universe’s structure as it exists today. (Image credit: NASA / WMAP Science Team)

    The hot Big Bang might have started our Universe as we know it some 13.8 billion years ago, but there’s a piece of it still visible to us today. Because the “bang” happened everywhere at once, there’s light that’s been traveling in all directions for 13.8 billion years, and some of it is just arriving at our eyes today. Because the Universe has been expanding this entire time, the wavelength of that initially hot light has gotten stretched, all the way from gamma rays through visible light and into the microwave portion of the spectrum. This leftover glow from the Big Bang shows up today as the Cosmic Microwave Background, or CMB. Today, it’s perhaps the best piece of evidence we have for what the Universe is made of.

    CMB per ESA/Planck
    CMB per ESA/Planck

    2
    The details in the Big Bang’s leftover glow have been progressively better and better revealed by improved satellite imagery. (Image credit: NASA/ESA and the COBE, WMAP and Planck teams)

    NASA COBE
    NASA COBE

    NASA/WMAP
    NASA/WMAP

    ESA/Planck
    ESA/Planck

    When it was first detected back in 1965, it was an incredible confirmation of the idea that the Universe came from a hot, dense, uniform state, with its temperature and spectrum matching the theory’s predictions exactly. But as our ability to measure the CMB’s imperfections grew and grew, we learned more than anyone in 1965 could have imagined. On average, the Big Bang’s leftover glow gives us a Universe whose temperature is 2.725 K, just a few degrees above absolute zero. But there are imperfections in that temperature as well if we look in different directions. They’re very small compared to the average temperature, with the “largest” imperfection coming in at just 3 millikelvins (mK).

    4
    The CMB dipole as measured by COBE, representing our motion through the Universe relative to the CMB’s rest frame. (Image credit: DMR, COBE, NASA, Four-Year Sky Map)

    This characteristic pattern — that it’s “hotter” in one direction and “cooler” in the opposite one — tells us how fast we’re moving through the Universe, relative to the rest frame of the expanding Universe. But if we subtract that out, we find that we have to go down to much smaller-magnitude fluctuations to find the temperature differences: microkelvin (µK) scales. If we go down that far, we get a snapshot of the tiny gravitational imperfections in the very young Universe. Thanks to the Planck satellite, we can see these imperfections down to angular scales of less than 0.1º.

    5
    COBE, the first CMB satellite, measured fluctuations to scales of 7º only. WMAP was able to measure resolutions down to 0.3° in five different frequency bands, with Planck measuring all the way down to just 5 arcminutes (0.08°) in nine different frequency bands in total. (Images credit: NASA/COBE/DMR; NASA/WMAP science team; ESA and the Planck collaboration).

    While these images might look like nothing more than noise to your eyes, there’s actually a tremendous amount of data packed in there. Imagine that you could divide the sky up a certain number of independent ways: 5, 15, 25, 150, etc., and measure how large the mean temperature fluctuation is on each and every scale. Every force and component of energy present in the Universe, including protons, neutrons and electrons, dark matter, radiation, dark energy, gravitational imperfections and more will influence how the fluctuations behave on each and every scale.

    8
    The composite maps (from l=2 to 10) of NASA Wilkinson Microwave Anisotropy Probe (WMAP) 3-year Internal Linear Combination (ILC) map. (Image credit: NASA / WMAP / Chiang Lung-Yih)

    Some spots are hotter than others; some are colder than others; some are exactly average. But by asking what the mean fluctuation is on each scale — by averaging the departure of the independent components from the mean together — we can quantify how the temperature varies at each angular scale. There’s a tremendous amount of information encoded in the results, and they enable us to determine exactly what makes up the Universe with just a little bit of extra information thrown in.

    11
    The power spectrum of the fluctuations in the CMB are best fit by a single, unique curve. Image credit: Planck Collaboration: P. A. R. Ade et al., 2014, A&A.

    The “line” of best-fit might look pretty arbitrary, but it’s actually extremely sensitive to a whole slew of different components in the Universe. On the left (the largest scales), the height and slope of the “flat” part tells us how deep the large-scale fluctuations are in the Universe and how they grow over time: the Sachs-Wolfe and Integrated Sachs-Wolfe effects. As you go to smaller scales, the height of that big, first peak tells us what the density of baryons (protons, neutrons and electrons combined) is: about 5% of the critical density. The angular scale — or horizontal location — of that peak tells us what the total curvature of the Universe is: about 0% (with an uncertainty of about 2%). The relative height of the second and third peaks tell us what the ratio of normal matter to dark matter is: about 1-to-5. Without dark matter, we’d have no second peak at all.

    12

    It’s worth noting that for any given line you draw, you can arrive at multiple different parameters. This is known as a degeneracy problem; you can’t determine everything by measuring the CMB on its own. But if you measure just one other thing — like the Hubble expansion rate, for example — you break that degeneracy completely.

    13
    When we do, with the best CMB data available (from Planck), we arrive at a Universe that’s made of:

    about 4.9% normal, atomic-based matter,
    about 0.01% photons,
    around 0.1% neutrinos,
    about 26.3% dark matter,
    no cosmic strings,
    no domain walls,
    and 68.7% cosmological constant, with no evidence for dark energy being anything more exotic than this.

    14
    The cold spots (shown in blue) in the CMB are not inherently colder, but rather represent regions where there is a greater gravitational pull due to a greater density of matter, while the hot spots (in red) are only hotter because the radiation in that region lives in a shallower gravitational well. Over time, the overdense regions will be much more likely to grow into stars, galaxies and clusters, while the underdense regions will be less likely to do so. (Image credit: E.M. Huff, the SDSS-III team and the South Pole Telescope team; graphic by Zosia Rostomian).

    This is consistent with everything else we’ve observed, from how structure forms on the largest scales to gravitational lensing to supernova data to dark matter in clusters and galaxies. Any alternative cosmology to the Big Bang governed by General Relativity with dark matter and dark energy has to rise to this challenge as well. So far, no alternative has ever succeeded on this front. With unprecedented precision, the CMB tells us exactly what’s in the Universe. Perhaps the most remarkable fact of all is how many independent lines of evidence support the same exact picture.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 2:30 pm on May 12, 2016 Permalink | Reply
    Tags: , , CMB research, ,   

    From LBL and Princeton: “$40M to Establish New Observatory Probing Early Universe” 

    Berkeley Logo

    Berkeley Lab

    May 12, 2016
    News Release

    LBL The Simons Array in the Atacama in Chile, with the  Atacama Cosmology Telescope
    The Simons Array will be located in Chile’s High Atacama Desert, at an elevation of about 17,000 feet. The site currently hosts the Atacama Cosmology Telescope (bowl-shaped structure at upper right) and the Simons Array (the three telescopes at bottom left, center and right). The Simons Observatory will merge these two experiments, add several new telescopes and set the stage for a next-generation experiment. (Credit: University of Pennsylvania)

    The Simons Foundation has given $38.4 million to establish a new astronomy facility in Chile’s Atacama Desert, adding new telescopes and detectors alongside existing instruments in order to boost ongoing studies of the evolution of the universe, from its earliest moments to today. The Heising-Simons Foundation is providing an additional $1.7 million for the project.

    The Simons Observatory is a collaboration among the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab); UC Berkeley; Princeton University; the University of California at San Diego; and University of Pennsylvania, all of which are also providing financial support.

    The project manager for the Simons Observatory will be located at Princeton, and Princeton faculty also will oversee the development, design, testing and manufacture of many of the observatory’s camera components.

    The observatory will probe the subtle properties of the universe’s first light, known as cosmic microwave background (CMB) radiation.

    A critical element in wringing new cosmological information from the CMB — which is the glow of heat left over from the Big Bang — is the use of densely packed, very sensitive cryogenic detectors. Princeton’s expertise with the detector development for the Atacama Cosmology Telescope in Chile and other observatories will complement the collaborative effort of the Simons Observatory, said Suzanne Staggs, Princeton’s project lead for the observatory and the Henry DeWolf Smyth Professor of Physics.

    Of particular importance is the University’s large dilution refrigerator-based camera testing facility located in the Department of Physics. The CMB has a temperature of 3 degrees Kelvin (-454.27 degrees Fahrenheit), and CMB detectors are more sensitive the colder they are. The Princeton facility will test the Simons Observatory equipment at a frosty 80 millikelvin, or eighty one-thousandths of a degree above absolute zero.

    Cosmic Microwave Background per ESA/Planck
    Cosmic Microwave Background per ESA/Planck

    ESA/Planck
    ESA/Planck

    The observatory will pay particular attention to the polarization, or directional information, in the CMB light to better understand what took place a fraction of a second after the Big Bang. While these events are hidden from view behind the glare of the microwave radiation, the disturbances they caused in the fabric of space-time affected the microwave’s polarization, and scientists hope to work backwards from these measurements to test theories about how the universe came into existence.

    “The Simons Observatory will allow us to peer behind the dust in our galaxy and search for a true signal from the Big Bang,” said Adrian Lee, a physicist at Berkeley Lab, a UC Berkeley physics professor and one of the lead investigators at the observatory.

    A key goal of the project is to detect gravitational waves generated by cosmic inflation, an extraordinarily rapid expansion of space that, according to the most popular cosmological theory, took place in an instant after the Big Bang. These primordial gravitational waves induced a very small but characteristic polarization pattern, called B-mode polarization, in the microwave background radiation that can be detected by telescopes and cameras like those planned for the Simons Observatory.

    “While patterns that we see in the microwave sky are a picture of the structure of the universe 380,000 years after the Big Bang, we believe that some of these patterns were generated much earlier, by gravitational waves produced in the first moments of the universe’s expansion,” said project spokesperson Mark Devlin, a cosmologist at the University of Pennsylvania who leads the university’s team in the collaboration. “By measuring how the gravitational waves affect electrons and matter 380,000 years after the Big Bang we are observing fossils from the very, very early universe.”

    Lee added, “Once we see the signal of inflation, it will be the beginning of a whole new era of cosmology.” We will then be looking at a time when the energy scale in the universe was a trillion times higher than the energy accessible in any particle accelerator on Earth.

    By measuring how radiation from the early universe changed as it traveled through space to Earth, the observatory also will teach us about the nature of dark energy and dark matter, the properties of neutrinos and how large-scale structure formed as the universe expanded and evolved.

    Two existing instruments at the site—the Atacama Cosmology Telescope and the Simons Array—are currently measuring this polarization. The foundation funds will merge these two experiments, expand the search and develop new technology for a fourth-stage, next-generation project—dubbed CMB-Stage 4 or CMB-S4—that could conceivably mine all the cosmological information in the cosmic microwave background fluctuations possible from a ground-based observatory.

    “We are still in the planning stage for CMB-S4, and this is a wonderful opportunity for the foundations to create a seed for the ultimate experiment,” said Akito Kusaka, a Berkeley Lab physicist and one of the lead investigators. “This gets us off to a quick start.”

    The Simons Observatory is designed to be a first step toward CMB-S4. This next-generation experiment builds on years of support from the National Science Foundation (NSF), and the Department of Energy (DOE) Office of Science has announced its intent to participate in CMB-S4, following the recommendation by its particle physics project prioritization panel [FNAL P5]. Such a project is envisioned to have telescopes at multiple sites and draw together a broad community of experts from the U.S. and abroad. The Atacama site in Chile has already been identified as an excellent location for CMB-S4, and the Simons Foundation funding will help develop it for that role.

    “We are hopeful that CMB-S4 would shed light not only on inflation, but also on the dark elements of the universe: neutrinos and so-called dark energy and dark matter,” Kusaka said. “The nature of these invisible elements is among the biggest questions in particle physics as well.”

    Beyond POLARBEAR

    Experiments at the Chilean site have already paved the way for CMB-S4. A 2012 UC Berkeley-led experiment with participation by Berkeley Lab researchers, called POLARBEAR, used a 3.5-meter telescope at the Chilean site to measure the gravitational-lensing-generated B-mode polarization of the cosmic microwave background radiation.

    POLARBEAR McGill Telescope located in the Atacama Desert of northern Chile in the Antofagasta Region. The POLARBEAR experiment is mounted on the Huan Tran Telescope (HTT) at the James Ax Observatory in the Chajnantor Science Reserve.
    POLARBEAR McGill Telescope located in the Atacama Desert of northern Chile in the Antofagasta Region. The POLARBEAR experiment is mounted on the Huan Tran Telescope (HTT) at the James Ax Observatory in the Chajnantor Science Reserve.

    Team scientists confirmed in 2014 that the signal was strong enough to allow them eventually to measure the neutrino mass and the evolution of dark energy.

    The recent addition of two more telescopes upgrades POLARBEAR to the Simons Array, which will speed up the mapping of the CMB and improve sky and frequency coverage. The $40 million in new funding will make possible the successor to the Simons Array and the nearby Atacama Cosmology Telescope.

    Current stage-3 experiments for these short-wavelength microwaves, which must be chilled to three-tenths of a degree Kelvin above absolute zero, have about 10,000 pixels, Lee said.

    “We need to make a leap in our technology to pave the way for the 500,000 detectors required for the ultimate experiment,” he said. “We’ll be generating the blueprint for a much more capable telescope.”

    “The generosity of this award is unprecedented in our field, and will enable a major leap in scientific capability,” said Brian Keating, leader of the UC San Diego contingent and current project director. “People are used to thinking about mega- or gigapixel detectors in optical telescopes, but for signals in the microwave range 10,000 pixels is a lot. What we’re trying to do—the real revolution here—is to pave the way to increase our pixels number by more than an order of magnitude.”

    Berkeley Lab and UC Berkeley will contribute $1.25 million in matching funds to the project over the next five years. The $1.7 million contributed by the Heising-Simons Foundation will be devoted to supporting research at Berkeley to improve the microwave detectors and to develop fabrication methods that are more efficient and cheaper, with the goal of boosting the number of detectors in CMB experiments by more than a factor of a 10.

    The site in Chile is located in the Parque Astronómico, which is administered by the Comisión Nacional de Investigación Científica y Tecnológica (CONICYT). Since 1998, U.S. investigators and the NSF have worked with Chilean scientists, the University of Chile, and CONICYT to locate multiple projects at this high, dry site to study the CMB.

    See the full LBL article here .

    See the full Princeton article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

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