1. Bernard Sadoulet: Shedding Light on the Dark Side of the Universe

    01:07:38

    from Steve Croft / Added

    187 Plays / / 0 Comments

    Bernard Sadoulet presents a public talk at UC Berkeley on December 17th, 2011, as part of the Science@Cal Lecture Series described at http://scienceatcal.berkeley.edu/lectures The last decade of cosmological observations tells us that 95% of the energy density in the universe is dark: the combination of about 25% of dark matter, whose nature is unknown and 70% of an even more mysterious dark energy. Ordinary matter only represents 5% of the energy budget. I will review attempts to shed light on this dark side of the universe, in particular current attempts to detect Weakly Interactive Massive Particles, which could make the dark matter. Bernard Sadoulet, a graduate of Ecole Polytechnique and a "Docteur des Sciences" of Paris-Orsay University, is by training an elementary particle physicist. He participated in two prestigious experiments which led to Nobel Prizes: the experiment at SLAC which discovered the J/y, the t lepton and the charm particles, and the experiment at CERN which discovered the W and Z particles. In 1984 he decided to shift his efforts towards particle astrophysics and cosmology. In 1985 he was appointed Professor of Physics at UC Berkeley, and from 1989 to 2001 he was the Director of the Center for Particle Astrophysics, one of the 11 first generation Science and Technology Centers of the National Science Foundation. He is currently Director of the UC system-wide Institute for Nuclear and Particle Astrophysics and Cosmology (INPAC). Videography and editing by Chris Klein, Andrew Siemion and James Anderson. This video is released under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 License - http://creativecommons.org/licenses/by-nc-sa/3.0/us

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    • Dark matter unnecessary to explain the mysterious spiral galaxy & dwarf spheroidal galaxy motion

      03:25

      from Oreka Particle / Added

      72 Plays / / 0 Comments

      Oreka Particle Theory explains and unifies the effects of dark energy and dark matter. It needs only the tiniest change to the law of gravity. It does not need the extra mass invented and made up "dark matter". This video is a selection from my paper http://vixra.org/abs/1111.0050 where I animated why spiral galaxy arms (the clouds around the center) rotate just as fast as the center when they shouldn't do this by their own visible mass. I also theorize on why dwarf spheroidal galaxies have stars moving at different speeds in different directions. Dwarf spheroidal galaxies are a mystery for scientists as to their varied movements and how they stay stable.

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      • dark matter

        01:24

        from Mario Huster / Added

        58 Plays / / 0 Comments

        Vertonung eines Animationstrailers Studienarbeit Gestaltung Ton Hochschule Ansbach

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        • Uncovering the Universe: Latest news from the LHC

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          from The Royal Institution / Added

          The Large Hadron Collider (LHC) at CERN is the most powerful particle collider ever built and has been described as the world's biggest science experiment. Designed to answer the unknowns in particle physics, including the reason for so little antimatter in the universe and the exact locations of dark matter and the missing Higgs particle, the LHC is capable of recreating the conditions that were in existence one fraction of a second after the Big Bang. Tara takes the stage at The Royal Institution to reveal what has been discovered at the LHC since its first year of operation. This event took place at the Ri on Wednesday 19 October 2011.

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          • Accelerating Universe - Sean Carroll, California Institute of Technology

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            from Kavli Frontiers of Science / Added

            170 Plays / / 0 Comments

            The Accelerating Universe: Enigmas and Nostrums. Sean Carroll, California Institute of Technology The universe is accelerating, and we don't know why. The simplest possibility goes back to Einstein: the possibility of a cosmological constant, or "vacuum energy." This is simply the idea that empty space itself has an inherent energy density, which remains absolutely constant throughout space and time. It's an idea that fits the data, but introduces a number of fine-tuning problems, which encourage cosmologists to look further. Another possibility is dynamical dark energy -- a source which is almost constant, but not quite, through space and time. Finally, we have the possibility that there isn't any new energy source of any kind; rather, our accepted notions of how gravity works (Einstein's general relativity) break down on cosmological scales. All of these ideas have their advantages and their drawbacks; the good news is that they make different predictions for cosmological observables. The next generation of experiments should go a long way towards pinning down the reason why the universe is accelerating.

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            • Detecting Dark Matter - Brian Odom, Northwestern University

              29:41

              from Kavli Frontiers of Science / Added

              80 Plays / / 0 Comments

              Dark but not Too Dark? Experimental Efforts to Detect Dark Matter Brian Odom, Northwestern University A broad range of astrophysical observations strongly suggest that most matter in the universe, so-called dark matter, is made of particles not yet discovered on earth and not accounted for within the current framework of physics. These dark matter particles evidently do interact with normal matter through gravity, but not via the much stronger electromagnetic or strong nuclear forces. While observations of far-away gravitational interactions give convincing evidence for the existence of dark matter, they can do very little to elucidate its properties. In order to determine the precise nature of dark matter, either “direct detection” or “indirect detection” would be required. Attempts at direct detection depend on the constant flow of dark matter through the earth. Direct detection experiments attempt to observe energy deposited in a detector as a result of collisions between dark matter particles and the detector material. Since it would be the well-named weak nuclear force giving rise to these collisions, events are expected to be quite rare, and much ingenuity is required to reduce false signals from natural radioactivity. Indirect detection experiments attempt to observe various types of secondary particles which might be created in dark matter on dark matter collisions. Astrophysical regions where such collision occur include the sun, the center of the Milky Way, and the early universe. Presently, a few interesting claims of direct and indirect detection remain unconfirmed, and many active research programs around the world are racing to achieve the first definitive detection of dark matter.

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              • Detecting Dark Matter - Mihoko M. Nojiri, High Energy Accelerator Research Organization(KEK)

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                from Kavli Frontiers of Science / Added

                152 Plays / / 0 Comments

                Detecting Dark Matter Mihoko M. Nojiri, High Energy Accelerator Research Organization(KEK) 1. Introduction Recent cosmological and astrophysical observations are accumulating evidences of existence of dark matter(DM). The DM has extremely weak interaction with ordinary matter around us. Current experimental limits and cosmological observations tell us that DMs are going through you … times per second without hitting you at all. Although it sounds mysterious, particle physicists have proposed reasonable answer why DM exists.Any weakly interacting particle which was once in the thermally produced in the early Universe can remain in the present Universe, if the particle has somehow protected to decay into lighter particles. The existence of dark matter in our universe suggests that there is one more conserved number—or a “symmetry” among the particles. If we know the particle interactions, we can even predict the density in the current Universe. It is simply inverse proportional to the strength of the interaction. The reason why we exists, namely, why baryons exists, may also be explained in the context of particle physics, but it is far more challenging. They have stronger interactions, which means the density calculated as above is simply too small. Number of baryons and antibaryons are predicted to be the same, while there are only baryons in our universe. 2. Why is the stable? Any deep reasons? There are many models which predict new particles, including the DM candidate. One of them is called supersymmetric (SUSY) model. In the model, there exists always SUSY particles as the partner of standard model particles. Namely, electron has its SUSY partner “selectron” and quark partner is squark. The special symmetry that makes dark matter particles stable is called “R-parity”. All SUSY particle has R parity -1 and all standard model (SM) particles has R=1, and all SUSY particle decay must involve at least one SUSY particle, and the lightest supersymmetic particle is stable. Supersymmetry also provides an elegant solution of the “hierarchy problem” of the SM Higgs boson. In the Standard model, Higgs boson is unstable against the radiative corrections, leading very unstable vacuum. The SUSY particles cooperate with SMl particles to make the vacuum stable. Other models which address both the DM and the hierarchy problem generally very similar to SUSY model. 3. Creating dark matter LHC smash two 7 TeV proton beams. The collisions of quarks and gluons are enough to create new particles with mass below a few TeV. The LHC therefore is able to create the dark matter just like the early Universe did it. Does the LHC have chance to study them? Experimentalists and theorists have been working on very hard to establish the way to find the SUSY particles. The LHC likely produce the pair of strongly interacting SUSY particles. The squark (partner of quark) and gluino (a partner of gluon. Gluon is responsible to the nuclear force) will be produced copiously. A Squark/gluino then decays into quarks, gluons, and a DM . At least two DMs are produced with each SUSY particle production at LHC. LHC detectors cannot detect the DM itself but see all the other decay products. The invisible DM momenta become missing energy of the events. Such events are rare in the SM processes, therefore SUSY particle can be discovers. 4 Weighting the dark matter Once the DM is discovered, we can determine the DM nature by looking into sparticle decay distributions. The decay distribution depends on the escaping DM mass and momentum. We can calculate the “mass of visible particles” and it cannot exceeds from the mass difference between squark and DM. DM velocity depends on the combination of momenta among the visible particles. By combining the information, DM mass can be determined. Furthermore many techniques has been developed to determine the mass, spin, and strength of the interactions of the DM, eventually allowing us to calculate the DM density of the Universe. We will compare the prediction with the observed dark matter density. If they agree, it means a big bang scenario is correct. If they do not agree, this means something unexpected happened in the early Universe. There are many speculations that this could be a case, and I will explain it as well.

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                • Detecting Dark Matter - Douglas Finkbeiner, Harvard-Smithsonian Center for Astrophysics

                  19:57

                  from Kavli Frontiers of Science / Added

                  143 Plays / / 1 Comment

                  Detecting Dark Matter Douglas Finkbeiner, Harvard-Smithsonian Center for Astrophysics One of the most remarkable discoveries in all of astronomy and physics in the last century is the existence of "dark matter." Dark matter interacts with ordinary matter gravitationally, but other types of interactions are so tremendously weak they have never been detected, even by decades of ambitious experiments. Dark matter is not dark because it fails to reflect light (like a lump of coal) or is unilluminated for some reason (like an orphan planet coasting through interstellar space). Dark matter is a fundamentally different material than the protons, neutrons, and electrons that make up the visible Universe. Amazingly, there is 5 times as much dark matter in the Universe as ordinary matter. We are in the minority! I will explain three reasons we think dark matter exists, and discuss why alternatives (such as modified laws of gravity) cannot be the explanation. I will then introduce the Weakly Interacting Massive Particle (WIMP), our best candidate for dark matter. Even though WIMPs interact very weakly with ordinary matter and light, there are still ways to detect them. On rare occasion, WIMPs could scatter off of atomic nuclei in very sensitive detectors deep underground. Particle accelerators could produce WIMPs, or other new particles closely related to them. Finally astronomers observing high-energy gamma-rays and cosmic-rays may be able to detect the remains of certain kinds of WIMP interactions. All of these strategies are being vigorously pursued, and we hope to know much more about dark matter in coming years. For further reading: http://www.eclipse.net/~cmmiller/DM/

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                  • Huntington Canyon First Ascent, Dark Matter

                    03:35

                    from Joe Meiners / Added

                    1,559 Plays / / 2 Comments

                    Chad Parkinson showed me an amazing line in Huntington Canyon. This new climb is called Dark Matter, V12. You can find it in Huntington Canyon, Utah. The boulder is at mile marker 34 on hwy 31.

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                    • A Talk on the Dark Side with Brian Greene

                      09:29

                      from Win Rosenfeld / Added

                      58 Plays / / 0 Comments

                      This week, two University of Louisiana astronomers announced that they may have stumbled across what might be a giant, never-seen-before planet on the outer reaches of our solar system. They’re calling it Tyche, and they’re hoping to get a good glimpse of it — whatever it turns out to be — in the next few months. After all, it’s a big universe out there, and even with our best telescopes and equations it’s hard for experts to agree on what it is they’re seeing in our own solar system. Now imagine how much harder it is to figure out what is happening at the edge of the universe. That’s what Dr. Brian Greene works on every day. Greene is a renowned theoretical physicist, and his new book, “The Hidden Reality,” has landed on The New York Times bestseller list. It explores some of the most literally out there thinking today. Greene spoke with Need to Know producer Win Rosenfeld to discuss multiple universes, dark energy and why astronomers of the future shouldn’t believe their eyes. Need to Know on PBS PBS, 2011

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