Tagged: Dark Matter and Dark Energy Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 4:27 pm on December 24, 2020 Permalink | Reply
    Tags: "Exploring the most unknown universe", , , , , Dark Matter and Dark Energy, Dark matter experiments way underground., ,   

    From University of Melbourne (AU): “Exploring the most unknown universe” 

    u-melbourne-bloc

    From University of Melbourne (AU)

    22 December 2020

    1
    We have powerful telescopes that can see very old galaxies and the beginnings of new ones. Credit: NASA.

    We know how the universe began, yet the data we have amassed in both particle physics and astronomy tells us that we still only know about a tiny fraction of the universe.

    Looking at the sky, we observe that on the largest scales, matter is organised into galaxies and clusters of galaxies.

    Galaxies contain stars, planets and gases. All the visible universe – the Earth, Sun, stars and galaxies, everything that makes ‘us’ – is made of protons, neutrons and electrons bundled together into atoms.

    Physicists have developed an impressive body of knowledge about the fundamental particles and forces that characterise the ordinary matter around us.

    Centuries of discovery have shown that apples fall from trees for the same reason that the Earth orbits the Sun, and that the Earth is not at the centre of the universe.

    It is a simple and elegant picture.

    The quest to answer the most basic questions about the universe has reached a singular moment. Astrophysical and cosmological observations have revealed that our picture of the universe is incomplete.

    2
    Dark matter’s fingerprints appear only when we look to the sky at the galactic and super-galactic scales. Picture: Getty Images.

    Perhaps one of the most surprising discoveries of the twentieth century was that ordinary matter makes up less than five per cent of the mass of the universe.

    The rest of the universe appears to be made of a mysterious, invisible substance named Dark Matter (25 per cent), and a force that repels gravity known as Dark Energy (70 per cent).

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

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

    Coma cluster via NASA/ESA Hubble.

    In modern times, it was astronomer Fritz Zwicky, in the 1930s, who made the first observations of what we now call dark matter. His 1933 observations of the Coma Cluster of galaxies seemed to indicated it has a mass 500 times more than that previously calculated by Edwin Hubble. Furthermore, this extra mass seemed to be completely invisible. Although Zwicky’s observations were initially met with much skepticism, they were later confirmed by other groups of astronomers.

    Thirty years later, astronomer Vera Rubin provided a huge piece of evidence for the existence of dark matter. She discovered that the centers of galaxies rotate at the same speed as their extremities, whereas, of course, they should rotate faster. Think of a vinyl LP on a record deck: its center rotates faster than its edge. That’s what logic dictates we should see in galaxies too. But we do not. The only way to explain this is if the whole galaxy is only the center of some much larger structure, as if it is only the label on the LP so to speak, causing the galaxy to have a consistent rotation speed from center to edge.

    Vera Rubin, following Zwicky, postulated that the missing structure in galaxies is dark matter. Her ideas were met with much resistance from the astronomical community, but her observations have been confirmed and are seen today as pivotal proof of the existence of dark matter.

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


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


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

    The Vera C. Rubin Observatory 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.

    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.

    The exotic unknown substance named dark matter doesn’t appear to absorb, reflect or emit light, rendering it ‘invisible’.

    Since dark matter interacts very weakly with normal matter, its existence is inferred due to its gravitational effects on galaxies. Its fingerprints appear only when we look to the sky at the galactic and super-galactic scales, at about 10 million times the distance between the Earth and the Sun.

    According to physics, stars at the edges of a spinning, spiral galaxy should travel much more slowly than those near the galactic centre, where a galaxy’s visible matter is concentrated. But our observations show that stars orbit at almost the same speed regardless of their distance from the centre of the galaxy.

    This puzzling result only makes sense if we assume that the boundary stars are feeling the gravitational effects of an unseen mass, a halo of dark matter enveloping the galaxy.

    Caterpillar Project A Milky-Way-size dark-matter halo and its subhalos circled, an enormous suite of simulations . Griffen et al. 2016.

    The existence of dark matter could also explain some optical illusions that astronomers see in the deep universe. For example, there are pictures displaying strange rings and arcs of light.

    3
    Installation view of Alicja Kwade’s work WeltenLinie 2020 on display in NGV Triennial 2020 from 19 December 2020 – 18 April 2021 at NGV International, Melbourne © Alicja Kwade, courtesy König Galerie, Berlin. Credit: Tom Ross.

    These can be explained if the light from distant galaxies is distorted and magnified by massive, invisible clouds of dark matter, in a phenomenon known as gravitational lensing.

    The radical conclusion that the universe is filled with invisible and nearly undetectable matter can be compared to Copernicus’s identification that the Earth is not the centre of the solar system – we have established that we don’t know what most of the universe is made of.

    Just like ordinary matter, dark matter also originated from the big bang.

    The amount of dark matter produced in the big bang has influenced the evolution of our universe.

    Similar to ordinary matter, dark matter isn’t distributed across the universe evenly. Areas of the universe that had slightly more dark matter, and so more gravitational pull, attracted more matter, leading to the creation of the first stars and galaxies.

    The cosmic web we observe today is a snapshot of the dark matter distribution in the early universe – this mysterious dark matter acted as a hidden hand guiding the growth of galaxies.

    Exploration of this unknown ‘new’ universe necessitates the discovery of the laws of physics underpinning the fundamental particle nature of dark matter. While astrophysical observations study the macroscopic properties of the universe to infer the existence of dark matter, terrestrial physics experiments are essential to study its quantum properties and consequently the fundamental laws of nature associated to dark matter.

    4
    The only way to detect dark matter collisions is to place our discovery machines deep underground. Picture: Supplied.

    One leading hypothesis is that dark matter is made up of exotic particles that don’t interact much with ordinary matter but are massive and therefore exert a gravitational pull.

    Under this assumption, we can derive some of the characteristics of dark matter.

    Cosmological measurements indicate that it is ‘cold’ – that is, the dark matter particles are heavy and move around the galaxy very slowly, much slower than the speed of light.

    Dark matter very rarely interacts with normal matter and is invisible to light and other forms of electromagnetic radiation, making it impossible to detect with current instruments. To build scientific instruments in order to ‘see’ dark matter, we need to hypothesise about what dark matter is.

    Most dark matter has probably been in existence since the first instant of the universe, outdating all atoms that make up visible matter. Earth is perpetually flying through a diffuse cloud of this mysterious substance.

    We face a constant shower of dark matter particles – every second, hundreds of thousands of dark matter particles zip through our bodies. However, dark matter particles interact so weakly that they pass right through us, leaving almost no sign of their visit.

    Looking at the density of dark matter throughout the universe, scientists calculate that of the thousands of dark matter particles passing through a human body every second, only about a dozen of them will collide with atoms in the body each year.

    6
    Installation view of Alicja Kwade’s work WeltenLinie 2020 on display in NGV Triennial 2020 from 19 December 2020 – 18 April 2021 at NGV International, Melbourne © Alicja Kwade, courtesy König Galerie, Berlin. Credit: Tom Ross.

    We cannot say what dark matter is until we can study it in a terrestrial laboratory. However, our very limited knowledge about the particle nature of dark matter makes building machines to discover it very challenging.

    That is an adventure on its own.

    Sometimes, very rarely indeed, a dark matter particle will collide with the nucleus of an atom, which can be detected in carefully designed direct detection experiments.

    The expected number of collisions of massive dark matter particles with nuclei of suitable detector materials is very small – less than one collision a year per kilogram of material.

    These collisions are so rare that on the Earth’s surface they are drowned out by the billions of cosmic ray–induced collisions that occur in the same kilogram of material each day.

    Looking for the signal produced by dark matter collisions is therefore like looking for a needle in a haystack.

    The only way to reduce the cosmic ray–induced collisions to a level where dark matter collisions are detectable is to place our discovery machines in deep underground sites where we can use the overlying rock layers (or ‘overburden’) as a shield against cosmic ray radiation.

    DEAP Dark Matter detector, The DEAP-3600, suspended in the SNOLAB (CA) deep in Sudbury’s Creighton Mine

    LBNL LZ Dark Matter project at SURF, Lead, SD, USA.

    Edelweiss Dark Matter Experiment, located at the Modane Underground Laboratory in France

    DAMA LIBRA Dark Matter Experiment, 1.5 km beneath Italy’s Gran Sasso mountain located in the Abruzzo region of central Italy.

    U Washington Lux Dark Matter 2 at SURF, Lead, SD, USA

    About one kilometre underground, far from the cosmic ray–induced particles, our discovery machines are waiting to catch dalliances of these elusive cosmic messengers with ordinary matter. From the depths of a mine shielded from cosmic rays, we can get a glimpse of one of the deepest mysteries of the universe.

    Experimental particle physics allows humankind to explore the secret of the universe at its fundamental level and to build machines that will enable this exploration.

    We have come to understand the fundamental building blocks of ordinary matter, and what we know of the universe is only a tiny fraction of what is out there.

    We know only five per cent of the universe. The remaining 95 per cent is still a mystery – an unknown universe of new particles and forces awaits discovery.

    Even if these unknown particles and forces are, at present, invisible to us, they have shaped the universe as we see it today. We are taking part in not only a scientific revolution, but also a revolution in how human beings see the universe.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    u-melbourne-campus

    The University of Melbourne (AU) (informally Melbourne University) is an Australian public research university located in Melbourne, Victoria. Founded in 1853, it is Australia’s second oldest university and the oldest in Victoria. Times Higher Education ranks Melbourne as 33rd in the world, while the Academic Ranking of World Universities places Melbourne 44th in the world (both first in Australia).

    Melbourne’s main campus is located in Parkville, an inner suburb north of the Melbourne central business district, with several other campuses located across Victoria. Melbourne is a sandstone university and a member of the Group of Eight, Universitas 21 and the Association of Pacific Rim Universities. Since 1872 various residential colleges have become affiliated with the university. There are 12 colleges located on the main campus and in nearby suburbs offering academic, sporting and cultural programs alongside accommodation for Melbourne students and faculty.

    Melbourne comprises 11 separate academic units and is associated with numerous institutes and research centres, including the Walter and Eliza Hall Institute of Medical Research, Florey Institute of Neuroscience and Mental Health, the Melbourne Institute of Applied Economic and Social Research and the Grattan Institute. Amongst Melbourne’s 15 graduate schools the Melbourne Business School, the Melbourne Law School and the Melbourne Medical School are particularly well regarded.

    Four Australian prime ministers and five governors-general have graduated from Melbourne. Nine Nobel laureates have been students or faculty, the most of any Australian university.

     
  • richardmitnick 9:17 am on August 25, 2020 Permalink | Reply
    Tags: "Will Radio Bursts Reveal Hidden Baryons?", , , , , , , Dark Matter and Dark Energy, , ,   

    From AAS NOVA: “Will Radio Bursts Reveal Hidden Baryons?” 

    AASNOVA

    From AAS NOVA

    24 August 2020
    Susanna Kohler

    Australian Square Kilometre Array Pathfinder (ASKAP) is a radio telescope array located at Murchison Radio-astronomy Observatory (MRO) in the Australian Mid West. ASKAP consists of 36 identical parabolic antennas, each 12 metres in diameter, working together as a single instrument with a total collecting area of approximately 4,000 square metres.


    Transients like fast radio bursts, detected with telescopes like the ASKAP array may be the key to identifying how much matter is hiding in our galaxy’s diffuse halo.

    The Earth, your body, and the electronic device you’re reading this on are all made up of ordinary, baryonic matter. A new study has now used bursts of radio emission to probe whether the outskirts of our galaxy are hiding vast quantities of “missing” baryonic matter.

    Missing Matter

    2
    The relative amounts of the different constituents of the universe. Ordinary baryonic matter makes up less than 5%. [ESA/Planck.]

    We’ve long known that only about 5% of the content of the universe is ordinary baryonic matter; the remainder is dark matter and dark energy. But when scientists have searched for this baryonic matter in the nearby universe, they found a puzzle: galaxies’ gas, dust, and stars only accounted for a small fraction of their expected baryonic matter.

    Our own Milky Way is no exception — it also has a baryon fraction much lower than the overall baryon fraction in the universe. So where are its missing baryons? Were they expelled from our galaxy at some point in the past? Or did the Milky Way retain its baryons — but we haven’t detected them yet?

    An Elusive Halo

    If our galaxy’s baryons are still around, a likely hiding place is in the Milky Way’s outskirts, in the circumgalactic medium (CGM).

    3
    The Sombrero galaxy, M104, provides an example of a galaxy and its halo — the diffuse gas that extends above and below the galaxy’s disk. [ESA/C. Carreau.]

    When our galaxy formed, gas was dragged inward with the collapsing dark-matter halo, shock heating and forming a surrounding bubble of hot, diffuse plasma — the CGM. This surrounding galactic halo may well contain our galaxy’s missing baryons today, but it’s very difficult to probe; since the gas is diffuse, we can’t measure it directly from within the Milky Way.

    A new study led by Emma Platts (University of Cape Town, South Africa) has instead measured the galactic halo’s matter by observing how distant signals interact with the CGM as they travel to us.

    Clues from Transients

    Platts and collaborators use two types of radio transients to measure CGM distribution: pulsars, which are pulsating neutron stars that reside in our galaxy’s disk, and fast radio bursts, which are brief flashes of radio emission that originate far beyond our galaxy.

    4
    Pulsars, which typically lie in the galactic disk, emit radiation that sweeps over the Earth like a lighthouse, appearing as pulses. These pulses become dispersed as they travel through the galaxy to reach us. [Bill Saxton/NRAO/AUI/NSF]

    Dame Susan Jocelyn Bell Burnell, discovered pulsars with radio astronomy. Jocelyn Bell at the Mullard Radio Astronomy Observatory, Cambridge University, taken for the Daily Herald newspaper in 1968. Denied the Nobel.

    Light from these sources travels across space to us, interacting with matter distributed along the way. The interactions slow down longer wavelengths of light more than shorter, causing the signal to spread out. The dispersion measure — the quantification of this spread — therefore tells us how much matter the signal traveled through to get to us.

    Probing Our Surroundings

    By statistically analyzing the distribution of pulsar and fast radio burst dispersion measures, Platts and collaborators placed bounds on the Milky Way halo’s dispersion measure: its minimum is set by the farthest pulsars, which lie interior to the halo, and its maximum is set by the closest fast radio bursts, which lie far beyond our halo in neighboring galaxies.

    Milky Way Halo NASA/ESA STScI

    So are the Milky Way’s missing baryons hiding in the CGM? We can’t say for certain yet, but the results suggest no, if the baryons are distributed in the same way as the dark matter. The future should hold more certainty though! Our sample of fast radio bursts is rapidly growing, and the authors estimate that once we’ve cataloged several thousand, we’ll be able to bound the content of the Milky Way’s halo more definitively.

    5
    Schematic illustrating how transient radio signals travel to us. Pulsars (marked by sun symbols) lie in the galaxy, interior to the halo; their signals are dispersed only by the Milky Way’s interstellar matter. Fast radio bursts (marked by lightning symbol) lie in other galaxies; their signals are dispersed by the Milky Way’s interstellar matter, its halo, the intergalactic medium, the host galaxy’s halo, and the host itself. These two types of transients can therefore place upper and lower bounds on the matter in the Milky Way’s halo. [Platts et al. 2020]

    Citation

    “A Data-driven Technique Using Millisecond Transients to Measure the Milky Way Halo,” E. Platts et al 2020 ApJL 895 L49.

    https://iopscience.iop.org/article/10.3847/2041-8213/ab930a

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

     
  • richardmitnick 12:57 pm on July 23, 2019 Permalink | Reply
    Tags: "NASA Delivers Hardware for ESA Dark Energy Mission", , , , , , Dark Matter and Dark Energy, , , , Near Infrared Spectrometer and Photometer (NISP) instrument, Thales Alenia Space   

    From European Space Agency and From NASA : “NASA Delivers Hardware for ESA Dark Energy Mission” 

    ESA Space For Europe Banner

    From European Space Agency

    and

    NASA image
    NASA

    July 23, 2019

    Calla Cofield
    Jet Propulsion Laboratory, Pasadena, Calif.
    626-808-2469
    calla.e.cofield@jpl.nasa.gov

    1
    The cryogenic (cold) portion of the Euclid space telescope’s Near Infrared Spectrometer and Photometer (NISP) instrument. NASA led the procurement and delivery of the detectors for the NISP instrument. The gold-coated hardware is the 16 sensor-chip electronics integrated with the infrared sensors.
    Credits: NASA/JPL-CaltechEuclid Consortium/CPPM/LAM

    ESA/Euclid spacecraft

    2
    Technicians with the manufacturer Thales Alenia Space work with the structural and thermal model of the Euclid telescope at their facility in Cannes, France.
    Credits: NASA/JPL-Caltech ESA/Thales Alenia Space/Airbus Defence and Space
    4
    4

    The European Space Agency’s Euclid mission, set to launch in 2022, will investigate two of the biggest mysteries in modern astronomy: dark matter and dark energy. A team of NASA engineers recently delivered critical hardware for one of the instruments that will fly on Euclid and probe these cosmic puzzles.

    Based at NASA’s Jet Propulsion Laboratory in Pasadena, California, and the Goddard Space Flight Center in Greenbelt, Maryland, the engineers designed, fabricated and tested 20 pieces of sensor-chip electronics (SCEs) hardware for Euclid (16 for the flight instrument and four backups).



    NASA JPL-Caltech Campus



    NASA Goddard Campus



    5
    Airbus Defence and Space

    These parts, which operate at minus 213 degrees Fahrenheit (minus 136 degrees Celsius), are responsible for precisely amplifying and digitizing the tiny signals from the light detectors in Euclid’s Near Infrared Spectrometer and Photometer (NISP) instrument. The Euclid observatory will also carry a visible-light imaging instrument.

    The image, taken in May 2019, above shows the detectors and sensor-chip electronics on a flight model of the NISP instrument in the Laboratory of Astrophysics of Marseille in France. Eighteen SCEs have been delivered to the European Space Agency (ESA), and two more will soon be on their way. The detector system will undergo extensive testing ahead of launch.

    “Even under the best of circumstances, it is extremely challenging to design and build very sensitive and complex electronics that function reliably at very cold operating temperatures,” said Moshe Pniel, the U.S. project manager for Euclid at JPL, who led the team that delivered the sensor-chip electronics. “This truly remarkable team, spread across two NASA centers, accomplished this task under intense schedule pressure and international attention.”

    Euclid will conduct a survey of billions of distant galaxies, which are moving away from us at a faster and faster rate as the expansion of space itself accelerates. Scientists don’t know what causes this accelerating expansion but have named the source of this phenomenon dark energy. By observing the effect of dark energy on the distribution of a large population of galaxies, scientists will try to narrow down what could possibly be driving this mysterious phenomenon.

    In addition, Euclid will provide insights into the mystery of dark matter. While we can’t see dark matter, it’s five times more prevalent in the universe than the “regular” matter that makes up planets, stars and everything else we can see in the universe.

    To detect dark matter, scientists look for the effects of its gravity. Euclid’s census of distant galaxies will reveal how the large-scale structure of the universe is shaped by the interplay of regular matter, dark matter and dark energy. This in turn will allow scientists to learn more about the properties and effects of both dark matter and dark energy in the universe, and to get closer to understanding their fundamental nature.

    The NISP instrument is led by the Laboratory of Astrophysics of Marseille, with contributions from 15 countries, including the United States, through an agreement between ESA and NASA.

    Three NASA-supported science groups contribute to the Euclid mission. In addition to designing and fabricating the NISP sensor-chip electronics, JPL led the procurement and delivery of the NISP detectors. Those detectors were tested at NASA’s Goddard Space Flight Center. The Euclid NASA Science Center at IPAC (ENSCI), at Caltech, will support U.S.-based investigations using Euclid data.

    For more information about Euclid go to:

    https://www.nasa.gov/mission_pages/euclid/main/index.html

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

    ESA50 Logo large

     
  • richardmitnick 11:18 am on May 7, 2019 Permalink | Reply
    Tags: "A universe is born", , , , , , , Dark Matter and Dark Energy, , , , , , The Planck epoch   

    From Symmetry: “A universe is born” 

    Symmetry Mag
    From Symmetry

    05/07/19
    Diana Kwon

    Take a (brief) journey through the early history of our cosmos.

    Timeline of the Inflationary Universe WMAP

    The universe was a busy place during the first three minutes. The cosmos we see today expanded from a tiny speck to much closer to its current massive size; the elementary particles appeared; and protons and neutrons combined into the first nuclei, filling the universe with the precursors of elements.

    By developing clever theories and conducting experiments with particle colliders, telescopes and satellites, physicists have been able to wind the film of the universe back billions of years—and glimpse the details of the very first moments in the history of our cosmic home.

    Take an abridged tour through this history:

    The Planck epoch
    Time: < 10^-43 seconds

    The Planck Epoch https:// http://www.slideshare.net ericgolob the-big-bang-10535251

    Welcome to the Planck epoch, named after the smallest scale of measurements possible in particle physics today. This is currently the closet scientists can get to the beginning of time.

    Theoretical physicists don’t know much about the earliest moments of the universe. After the Big Bang theory gained popularity, scientists thought that in the first moments, the cosmos was at its hottest and densest and that all four fundamental forces—electromagnetic, weak, strong and gravitational—were combined into a single, unified force. But the current leading theoretical framework for our universe’s beginning doesn’t necessarily require these conditions.

    The universe expands
    Time: From 10^-43 seconds to about 10^-36 seconds

    In this stage, which began either at Planck time or shortly after it, scientists think the universe underwent superfast, exponential expansion in a process known as inflation.

    Inflation

    4
    Alan Guth, from Highland Park High School and M.I.T., who first proposed cosmic inflation

    HPHS Owls

    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex MittelmannColdcreation

    Alan Guth’s notes:
    5

    Physicists first proposed the theory of inflation in the 1980s to address the shortcomings of the Big Bang theory, which, despite its popularity, could not explain why the universe was so flat and uniform, and why its different parts began expanding simultaneously.

    During inflation, quantum fluctuations could have stretched out to produce a pattern that later determined the locations of galaxies. It might have been only after this period of inflation the universe became a hot, dense fireball as described in the Big Bang theory.

    The elementary particles are born
    Time: ~10^-36 seconds

    When the universe was still very hot, the cosmos was like a gigantic accelerator, much more powerful than the Large Hadron Collider, running at extremely high energies. In it, the elementary particles we know today were born.

    Scientists think that first came exotic particles, followed by more familiar ones, such as electrons, neutrinos and quarks. It could be that dark matter particles came about during this time.

    3
    Quarks APS/Alan Stonebraker

    The quarks soon combined, forming the familiar protons and neutrons, which are collectively known as baryons. Neutrinos were able to escape this plasma of charged particles and began traveling freely through space, while photons continued to be trapped by the plasma.

    Standard Model of Particle Physics

    The first nuclei emerge
    Time: ~1 second to 3 minutes

    Scientists think that when the universe cooled enough for violent collisions to subside, protons and neutrons clumped together into nuclei of the light elements—hydrogen, helium and lithium—in a process known as Big Bang nucleosynthesis.

    Protons are more stable than neutrons, due to their lower mass. In fact, a free neutron decays with a 15-minute half-life, while protons may not decay at all, as far as we know.

    So as the particles combined, many protons remained unpaired. As a result, hydrogen—protons that never found a partner—make up around 74% of the mass of “normal” matter in our cosmos. The second most abundant element is helium, which makes up approximately 24%, followed by trace amounts of deuterium, lithium, and helium-3 (helium with a three-baryon core).

    Periodic table Sept 2017. Wikipedia

    Scientists have been able to accurately measure the density of baryons in our universe. Most of those measurements line up with theorists’ estimations of what the quantities ought to be, but there is one lingering issue: Lithium calculations are off by a factor of three. It could be that the measurements are off, but it could also be that something we don’t yet know about happened during this time period to change the abundance of lithium.

    The cosmic microwave background becomes visible
    Time: 380,000 years

    Hundreds of thousands of years after inflation, the particle soup had cooled enough for electrons to bind to nuclei to form electrically neutral atoms. Through this process, which is also known as recombination, photons became free to traverse the universe, creating the cosmic microwave background.

    CMB per ESA/Planck


    ESA/Planck 2009 to 2013

    Today, the CMB is one of the most valuable tools for cosmologists, who probe its depths in search of answers for many of the universe’s lingering secrets, including the nature of inflation and the cause of matter-antimatter asymmetry.

    Shortly after the CMB became detectable, neutral hydrogen particles formed into a gas that filled the universe. Without any objects emitting high-energy photons, the cosmos was plunged into the dark ages for millions of years.

    Dark Energy Camera Enables Astronomers a Glimpse at the Cosmic Dawn. CREDIT National Astronomical Observatory of Japan

    The earliest stars shine
    Time: ~100 million years

    The dark ages ended with the formation of the first stars and the occurrence of reionization, a process through which highly energetic photons stripped electrons off neutral hydrogen atoms.

    Reionization era and first stars, Caltech

    Scientists think that the vast majority of the ionizing photons emerged from the earliest stars. But other processes, such as collisions between dark matter particles, may have also played a role.

    At this time, matter began to form the first galaxies. Our own galaxy, the Milky Way, contains stars that were born when the universe was only several hundred million years old.

    Milky Way NASA/JPL-Caltech /ESO R. Hurt

    Our sun is born
    Time: 9.2 billion years

    3
    NASA

    The sun is one of a few hundred billion stars in the Milky Way. Scientists think it formed from a giant cloud of gas that consisted mostly hydrogen and helium.

    Today
    Time: 13.8 billion years

    Today, our cosmos sits at a cool 2.7 Kelvin (minus 270.42 degrees Celsius). The universe is expanding at an increasing rate, in a manner similar to (but many orders of magnitude slower than) inflation.

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    Physicists think that dark energy—a mysterious repulsive force that currently accounts for about 70% of the energy in our universe—is most likely driving that accelerated expansion.

    Dark energy depiction. Image: Volker Springle/Max Planck Institute for Astrophysics/SP)

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.


    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.


     
  • richardmitnick 10:05 pm on March 8, 2018 Permalink | Reply
    Tags: , , , , , , , , , , Dark Matter and Dark Energy, International Women's Day, , , , , ,   

    From PI: Women in STEM-“Celebrating International Women’s Day” 

    4

    Is it not a shame that we need to have a special day to celebrate women when they are so already fantastic and exceptionally brilliant in the physical sciences?

    Check out this blog post-
    https://sciencesprings.wordpress.com/2018/03/08/from-the-conversation-women-in-stem-perish-not-publish-new-study-quantifies-the-lack-of-female-authors-in-scientific-journals/

    “”I have done a couple of STEM events, but there have never been this many girls. There are so many here. It is really empowering. Go girls in STEM!” Eama, Grade 12

    Today’s Inspiring Future Women in Science conference was a success. Mona Nemar, Canada’s Chief Science Advisor, gave opening remarks encouraging the students in attendance to take advantage of the opportunity to learn from the speakers to come.

    2
    “The days of women being held back or being excluded from science are over. Now, more than ever women are entering, remaining in, and revolutionizing the science fields. Today is a shining example of that.”
    -Mona Nemar, Chief Science Advisor, Government of Canada

    Mona, read my above post on women getting not published.

    The speakers and panelists, who included a chemist, engineer, astronomer, ecologist, and surgeon, talked about the challenges and triumphs that a career in STEM brings. Students were then treated to a speed mentoring session where they were able to ask questions and interact with women from a broad number of STEM careers. Read more about how this conference is inspiring young women here.

    3
    “This conference showed me there are so many things you can do going into [a career in STEM], so now I feel more inspired, and I feel more confident and not scared to go into science.” Lealan, Age 16

    Programs like Perimeter’s “Inspiring Future Women in Science” conference are helping young women see their own potential and reach out for careers in STEM. And more talented female scientists today, means a brighter future tomorrow.

    Thank you for being part of the equation.
    4

     
  • richardmitnick 12:48 pm on November 2, 2017 Permalink | Reply
    Tags: Apache Spark open-source software, , Dark Matter and Dark Energy, ,   

    From ASCRDiscovery: “A Spark in the dark” 

    ASCRDiscovery
    Advancing Science Through Computing

    October 2017

    The cosmological search in the dark is no walk in the park. With help from Berkeley Lab’s NERSC, Fermilab [FNAL] aims open-source software at data from high-energy physics.

    NERSC Cray Cori II supercomputer

    LBL NERSC Cray XC30 Edison supercomputer


    The Genepool system is a cluster dedicated to the DOE Joint Genome Institute’s computing needs. Denovo is a smaller test system for Genepool that is primarily used by NERSC staff to test new system configurations and software.

    NERSC PDSF


    PDSF is a networked distributed computing cluster designed primarily to meet the detector simulation and data analysis requirements of physics, astrophysics and nuclear science collaborations.

    1
    Proposed filaments of dark matter surrounding Jupiter could be part of the mysterious 95 percent of the universe’s mass-energy. Image courtesy of NASA/JPL-Caltech.

    Most of the universe is dark, with dark matter and dark energy comprising more than 95 percent of its mass-energy. Yet we know little about dark matter and energy. To find answers, scientists run huge high-energy physics experiments. Analyzing the results demands high-performance computing – sometimes balanced with industrial trends.

    After four years of running computing for the Large Hadron Collider CMS experiment at CERN near Geneva, Switzerland – part of the work that revealed the Higgs boson – Oliver Gutsche, a scientist at Department of Energy’s (DOE) Fermi National Accelerator Laboratory, turned to the search for dark matter.

    CERN CMS Higgs Event


    CERN/CMS Detector


    “The Higgs boson had been predicted, and we knew approximately where to look,” he says. “With dark matter, we don’t know what we’re looking for.”

    To learn about dark matter, Gutsche needs more data. Once that information is available, physicists must mine it. They are exploring computational tools for the job, including Apache Spark open-source software.

    In searching for dark matter, physicists study results from colliding particles. “This is trivial to parallelize,” breaking the job into pieces to get answers faster, Gutsche explains. “Two PCs can each process a collision,” meaning researchers can employ a computer grid to analyze data.

    Much of the work in high-energy physics, though, depends on software the scientists develop. “If our graduate students and postdocs only know our proprietary tools, then they’ll have trouble if they go to industry,” where such software is unavailable, Gutsche notes. “So I started to look into Spark.”

    3
    To search for dark matter, scientists collect and analyze results from colliding particles, an extremely computationally intense process. Image courtesy of CMS CERN.

    Spark is a data-reduction tool made for unstructured text files. That creates a challenge – accessing the high-energy physics data, which are in an object-oriented format. Fermilab computer science researchers Saba Sehrish and Jim Kowalkowski are tackling the task.

    Spark offered promise from the beginning, with some particularly interesting features, Sehrish says. “One was in-memory, large-scale distributed processing” through high-level interfaces, which makes it easy to use. “You don’t want scientists to worry about how to distribute data and write parallel code,” she says. Spark takes care of that.

    Another attractive feature: Spark is a supported research platform at the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science user facility at the DOE’s Lawrence Berkeley National Laboratory.

    “This gives us a support team that can tune it,” Kowalkowski says. Computer scientists like Sehrish and Kowalkowski can add capabilities, but making the underlying code work as efficiently as possible requires Spark specialists, some of whom work at NERSC.

    Kowalkowski summarizes Spark’s desirable features as “automated scaling, automated parallelism and a reasonable programming model.”

    In short, he and Sehrish want to build a system allowing researchers to run an analysis that performs extremely well on large-scale machines without complications and through an easy user interface.

    Just being easy to use, though, is not enough when dealing with data from high-energy physics. Spark appears to satisfy both ease-of-use and performance goals to some degree. Researchers are still investigating some aspects of its performance for high-energy physics applications, but computer scientists can’t have everything. “There is a compromise,” Sehrish states. “When you’re looking for more performance, you don’t get ease of use.”

    The Fermilab scientists selected Spark as an initial choice for exploring big-data science, and dark matter is just the first application under testing. “We need several real-use cases to understand the feasibility of using Spark for an analysis task,” Sehrish says. With scientists like Gutsche at Fermilab, dark matter was a good place to start. Sehrish and Kowalkowski want to simplify the lives of scientists running the analysis. “We work with scientists to understand their data and work with their analysis,” Sehrish says. “Then we can help them better organize data sets, better organize analysis tasks.”

    As a first step in that process, Sehrish and Kowalkowski must get data from high-energy physics experiments into Spark. Notes Kowalkowski, “You have petabytes of data in specific experimental formats that you have to turn into something useful for another platform.”

    The starting data for the dark-matter implementation are formatted for high-throughput computing platforms, but Spark doesn’t handle that configuration. So software must read the original data format and convert it to something that works well with Spark.

    In doing this, Sehrish explains, “you have to consider every decision at every step, because how you structure the data, how you read it into memory and design and implement operations for high performance is all linked.”

    Each of those data-handling steps affects Spark’s performance. Although it’s too early to tell how much performance can be pulled from Spark when analyzing dark-matter data, Sehrish and Kowalkowski see that Spark can provide user-friendly code that allows high-energy physics researchers to launch a job on hundreds of thousands of cores. “Spark is good in that respect,” Sehrish says. “We’ve also seen good scaling – not wasting computing resources as we increase the dataset size and the number of nodes.”

    No one knows if this will be a viable approach until determining Spark’s peak performance for these applications. “The main key,” Kowalkowski says, “is that we are not convinced yet that this is the technology to go forward.”

    In fact, Spark itself changes. Its extensive open-source use creates a constant and rapid development cycle. So Sehrish and Kowalkowski must keep their code up with Spark’s new capabilities.

    “The constant cycle of growth with Spark is the cost of working with high-end technology and something with a lot of development interests,” Sehrish says.

    It could be a few years before Sehrish and Kowalkowski make a decision on Spark. Converting software created for high-throughput computing into good high-performance computing tools that are easy to use requires fine tuning and team work between experimental and computational scientists. Or, you might say, it takes more than a shot in the dark.

    A DOE Office of Science laboratory, Fermilab [FNAL] is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance LLC. The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit http://science.energy.gov.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    ASCRDiscovery is a publication of The U.S. Department of Energy

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
%d bloggers like this: