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Keyword: darkenergy

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  • Does Dark Energy Exist?

    07/01/2017 7:01:15 PM PDT · by ETL · 55 replies
    Space.com ^ | June 28, 2017 | Paul Sutter, Astrophysicist
    Newsflash: the universe is expanding. We've known that since the pioneering and tireless work of Edwin Hubble about a century ago, and it's kind of a big deal. But before I talk about dark energy and why that's an even bigger deal, I need to clarify what we mean by the word "expanding." The actual observation that you can do in the comfort of your own home (provided you have access to a sufficiently large telescope and a spectrograph) is that galaxies appear to be receding from our own Milky Way. On average, of course: galaxies aren't simple creatures, and...
  • How to catch a ripple in spacetime

    06/19/2016 12:26:13 PM PDT · by MtnClimber · 16 replies
    Ideas.ted.com ^ | 17 Jun, 2016 | Janna Levin
    How do you build a real-world machine to test the most abstract of theories? Janna Levin talks with Rai Weiss, one of the original designers of LIGO, the four-kilometer-long instrument that has now twice detected the distant reverberations of two black holes crashing into one another. Janna Levin is a theoretical physicist — she works with pen and paper to turn the elegant rules of the universe into theory. Rainer Weiss, or Rai, as he’s known, is an experimental physicist — he thinks about how to find and measure something that may or may not exist outside of theory. Weiss...
  • Do We Need to Revise General Relativity?

    05/20/2016 11:56:18 AM PDT · by MtnClimber · 39 replies
    Real Clear Science ^ | Ross Pomeroy
    The idea that our Universe is filled with dark matter has been around for nearly a century. When astronomers noticed that orbital speeds towards the edges of spiral galaxies remain the same or even increase slightly, rather than decrease, they surmised that either there must be some huge unseen mass driving the rotation, or that the laws of gravity given by Einstein's General Relativity need to be changed. They elected the first option. Over that time, cosmologists have accumulated boatloads of evidence in favor of the notion that this invisible, "dark" matter -- which neither interacts with nor emits light...
  • Astronomy Picture of the Day -- LIGO Detects Gravitational Waves from Merging Black Holes

    02/11/2016 4:37:17 PM PST · by SunkenCiv · 30 replies
    NASA ^ | February 11, 2016 | (see photo credit)
    Explanation: Gravitational radiation has been directly detected. The first-ever detection was made by both facilities of the Laser Interferometer Gravitational-Wave Observatory (LIGO) in Washington and Louisiana simultaneously last September. After numerous consistency checks, the resulting 5-sigma discovery was published today. The measured gravitational waves match those expected from two large black holes merging after a death spiral in a distant galaxy, with the resulting new black hole momentarily vibrating in a rapid ringdown. A phenomenon predicted by Einstein, the historic discovery confirms a cornerstone of humanity's understanding of gravity and basic physics. It is also the most direct detection of...
  • Galactic center's gamma rays unlikely to originate from dark matter, evidence shows

    02/05/2016 1:08:03 PM PST · by MtnClimber · 15 replies
    Princeton University ^ | 4 Feb, 2016 | Catherine Zandonella, Office of the Dean for Research
    Bursts of gamma rays from the center of our galaxy are not likely to be signals of dark matter but rather other astrophysical phenomena such as fast-rotating stars called millisecond pulsars, according to two new studies, one from a team based at Princeton University and the Massachusetts Institute of Technology and another based in the Netherlands. Previous studies suggested that gamma rays coming from the dense region of space in the inner Milky Way galaxy could be caused when invisible dark matter particles collide. But using new statistical analysis methods, the two research teams independently found that the gamma ray...
  • Black holes can grow to 50 billion times the mass of the Sun... and then stop

    12/21/2015 1:15:25 PM PST · by Red Badger · 32 replies
    www.ibtimes.co.uk ^ | December 21, 2015 12:30 GMT | By Matt Atherton
    Black holes can only grow if they have a gas disc to feed on NASA Goddard Space Flight Center/Flickr ======================================================================================================== Black holes can only grow to 50 billion times the mass of the Sun, before they lose their only source of 'food' and stop growing. Scientists discovered that black holes have a size limit, as when it gets so big, the gas which feeds the great void loses its energy, and falls into the unknown. A researcher from the University of Leicester analysed the disc of gas which surrounds supermassive black holes at the centre of galaxies. He found that...
  • Dark matter and the dinosaur: New theory challenges notions on origins of human life

    12/12/2015 1:32:59 AM PST · by Squawk 8888 · 22 replies
    National Post ^ | December 12, 2015 | Joseph Brean
    TORONTO — Dark matter inspires many strange theories, but until now few have involved giant lizards and the origins of humanity. If physicist Lisa Randall’s theory is correct, however, there is a clear link between dark matter, the great unknown majority of universal stuff and the extinction of the dinosaurs, which cleared the path for the rise of mammals, including that special species, homo sapiens. Roughly, her idea is that the rotation of a vast disc of dark matter through our solar system dislodged an asteroid from a weak and distant orbit, and sent it hurtling toward Earth, where it...
  • Astronomy Picture of the Day -- A Force from Empty Space: The Casimir Effect

    12/05/2015 10:01:56 PM PST · by SunkenCiv · 11 replies
    NASA ^ | December 06, 2015 | (see photo credit)
    Explanation: This tiny ball provides evidence that the universe will expand forever. Measuring slightly over one tenth of a millimeter, the ball moves toward a smooth plate in response to energy fluctuations in the vacuum of empty space. The attraction is known as the Casimir Effect, named for its discoverer, who, 55 years ago, was trying to understand why fluids like mayonnaise move so slowly. Today, evidence indicates that most of the energy density in the universe is in an unknown form dubbed dark energy. The form and genesis of dark energy is almost completely unknown, but postulated as related...
  • Is Earth Growing a Hairy Dark Matter 'Beard'?

    11/23/2015 4:24:17 PM PST · by BenLurkin · 37 replies
    discovery.com ^ | Nov 23, 2015 03:48 PM ET // by | Ian O'Neill
    Gary Prezeau of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., describes the results of his theoretical model that goes some way to explain how streams of dark matter particles may interact with our planet's gravitational field. "A (dark matter) stream can be much larger than the solar system itself, and there are many different streams crisscrossing our galactic neighborhood," said Prézeau in a JPL press release. "When gravity interacts with the cold dark matter gas during galaxy formation, all particles within a stream continue traveling at the same velocity." As these streams begin to interact with a planet, according to...
  • Leading Harvard physicist has a radical new theory for why humans exist

    11/15/2015 7:47:38 AM PST · by SeekAndFind · 63 replies
    Business Insider ^ | 11/15/2015 | Jessica Orwig
    Where do we come from? There are many right answers to this question, and the one you get depends on who you ask. For example, an astrophysicist might say that the chemical components of our bodies were first forged in the nuclear fires of stars. On the other hand, an evolutionary biologist might look at the similarities between our DNA and that of other primates' and conclude we evolved from apes. Lisa Randall, a theoretical physicist at Harvard University, has a different, and novel answer, which she describes in her latest book, "Dark Matter and the Dinosaurs." Randall has written...
  • The Astronomer Who Wanted to Rearrange the Solar System, Using Nukes

    CalTech astronomer Fritz Zwicky was the first to conceive of dark matter, supernovas and neutron stars. He also had a theory about colonizing the solar system using nuclear bombs. We could terraform other planets, he argued, by pulverizing them and then moving them closer or further from the sun. ...
  • What are white holes?

    10/12/2015 8:35:22 AM PDT · by Red Badger · 40 replies
    phys.org ^ | October 9, 2015 | by Fraser Cain, Universe Today
    White Hole. Credit: universe-review.ca =================================================================================================================== Black holes are created when stars die catastrophically in a supernova. So what in the universe is a white hole? It's imagination day, and we're going to talk about fantasy creatures. Like unicorns, but even rarer. Like leprechauns, but even more fantastical! Today, we're going to talk about white holes. Before we talk about white holes, let's talk about black holes. And before we talk about Black Holes, what's is this thing you have with holes exactly? Black holes are places in the universe where matter and energy are compacted so densely together that their...
  • Goodbye Big Bang, Hello Black Hole? A New Theory Of The Universe’s Creation

    09/30/2015 7:10:11 PM PDT · by lbryce · 40 replies
    Universe Today ^ | September 18, 2015 | ELIZABETH HOWELL on SEPTEMBER 18, 2013
    Could the famed “Big Bang” theory need a revision? A group of theoretical physicists suppose the birth of the universe could have happened after a four-dimensional star collapsed into a black hole and ejected debris. Before getting into their findings, let’s just preface this by saying nobody knows anything for sure. Humans obviously weren’t around at the time the universe began. The standard theory is that the universe grew from an infinitely dense point or singularity, but who knows what was there before? “For all physicists know, dragons could have come flying out of the singularity,” stated Niayesh Afshordi, an...
  • The Case for Complex Dark Matter

    08/20/2015 7:50:41 PM PDT · by LibWhacker · 30 replies
    Quanta Magazine ^ | 8/20/15 | Liz Kruesi
    The Case for Complex Dark Matter The physicist James Bullock explains how a complicated “dark sector” of interacting particles may illuminate some puzzling observations of the centers of galaxies. Jonathan Alcorn for Quanta MagazineJames Bullock, a physicist at the University of California, Irvine, imagines what the universe would look like if dark matter interacted with itself. By: Liz KruesiAugust 20, 2015 Dark matter — the unseen 80 percent of the universe’s mass — doesn’t emit, absorb or reflect light. Astronomers know it exists only because it interacts with our slice of the ordinary universe through gravity. Hence the hunt for this...
  • Scientists Map the ["inferred"] Dark Matter Around Millions of Galaxies

    04/17/2015 2:15:22 PM PDT · by BenLurkin · 28 replies
    universetoday.com ^ | Ramin Skibba
    The research and maps, which span a large area of the sky, are the product of a massive effort of an international team from the US, UK, Spain, Germany, Switzerland, and Brazil. They announced their new results at the American Physical Society (APS) meeting in Baltimore, Maryland. According to cosmologists, dark matter particles stream and clump together over time in particular regions of the cosmos, often in the same places where galaxies form and cluster. Over time, a “cosmic web” develops across the universe. Though dark matter is invisible, it expands with the universe and feels the pull of gravity....
  • Fact or Fiction?: Dark Matter Killed the Dinosaurs

    04/02/2015 10:15:04 PM PDT · by grundle · 58 replies
    Scientific American ^ | March 25, 2015 | Lee Billings
    A new out-of-this-world theory links mass extinctions with exotic astrophysics and galactic architecture Every once in a great while, something almost unspeakable happens to Earth. Some terrible force reaches out and tears the tree of life limb from limb. In a geological instant, countless creatures perish and entire lineages simply cease to exist. The most famous of these mass extinctions happened about 66 million years ago, when the dinosaurs died out in the planet-wide environmental disruption that followed a mountain-sized space rock walloping Earth. We can still see the scar from the impact today as a nearly 200-kilometer-wide crater in...
  • Dark matter is apparently ‘darker’ than we thought

    03/27/2015 8:14:51 PM PDT · by BenLurkin · 48 replies
    WaPo ^ | Rachel Feltman
    A new study published Thursday in Science suggests that dark matter might be able to zip through the universe without slowing or dragging because particles of it don't even interact with each other. Based on what we can observe about the universe, galaxies should be tearing themselves apart. That's where so-called dark matter comes in: It's a term for the as-of-yet unobserved matter that must be bulking up cosmos, giving galaxies the gravity they need to spin at the rates they do without falling to pieces. But even though we haven't caught dark matter (so named because it doesn't interact...
  • How Do We Know Dark Matter Exists?

    03/12/2015 10:32:02 AM PDT · by BenLurkin · 46 replies
    universetoday.com ^ | Fraser Cain
    Now, you might be saying, if we don’t know what this thing is, and we can’t detect it. How do we know it’s actually there? Isn’t it probably not there, like dragons? How do we know dark matter actually exists, when we have no idea what it actually is? Oh, it’s there. In fact, pretty much all we know is that it does exist. Dark matter was first theorized back in the 1930s by Fritz Zwicky to account for the movement of galaxy clusters, but the modern calculations were made by Vera Rubin in the 1960s and 70s. She calculated...
  • Does Dark Matter Originate From Higgs Boson? New Theory To Be Tested At CERN's LHC

    03/07/2015 10:57:00 AM PST · by BenLurkin · 24 replies
    ibtimes.com ^ | Avaneesh Pandey 
    Dark matter has long remained one of the greatest unsolved mysteries of the universe. While its presence can be inferred from the gravitational pull it exerts on visible matter, the fact that it does not emit or absorb any radiation makes it next to impossible to detect. ... The new model put forward by a team headed by Christoffer Petersson, a theoretical particle physicist from Chalmers University of Technology in Sweden, suggests that the Higgs boson, discovered by the LHC in 2012, might be responsible for the birth of dark matter particles. According to this model, if supersymmetry is real,...
  • Black hole 12bn times more massive than sun is discovered

    02/28/2015 10:32:14 AM PST · by Ernest_at_the_Beach · 60 replies
    theguardian.com ^ | Feb 25, 2015 | Press Association
    Scientists name new ‘object’ SDSS J0100+2802 and say it is 12.8bn light years from Earth and was formed just 900m years after the Big Bang *************************************************************A monster black hole powering “the brightest lighthouse in the distant universe” has been discovered that is 12bn times more massive than the sun, scientists have revealed.The extraordinary object is at the centre of a quasar - an intensely powerful galactic radiation source - with a million billion times the sun’s energy output.For years the nature of quasars, discovered in 1963, remained a mystery. Today scientists believe they are generated by matter heating up as...