Bulletin of the American Physical Society
Joint Meeting of the Four Corners and Texas Sections of the American Physical Society
Volume 61, Number 15
Friday–Saturday, October 21–22, 2016; Las Cruces, New Mexico
Session K1: Plenary V |
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Chair: Heather Galloway, Texas State University, San Marcos Room: Exhibit Hall 2 |
Saturday, October 22, 2016 2:36PM - 3:12PM |
K1.00001: The Matter Anti-Matter Asymmetry of the Universe: Why is there something, rather than nothing? Invited Speaker: David Nygren Our universe is filled with matter, but antimatter is evanescent, rarely found and only in the debris of high-energy processes and cosmic rays. Yet the standard model of particle physics and cosmic evolution postulates that the universe started out completely symmetric between matter and antimatter, and that only about 1 proton or neutron in 10$^{20}$ should have escaped annihilation into photons. The measured ratio, however, of baryons–protons and neutrons–to the photons left over is about 6 x 10$^{-10}$, about ten orders of magnitude greater. At some very early moment, something broke the initial symmetry of the universe, eventually yielding the stars, galaxies, and the universe we inhabit and explore today. How did this happen? I will discuss how one attractive theory-that neutrinos have very massive unstable partners that distinguish between matter and antimatter, did their work and then disappeared, and how we might learn something about this scenario by searching for an almost unimaginably rare nuclear decay–without the emission of today’s light neutrinos–and how biochemistry might help us succeed. Strangely enough, if we do observe the decay, we also learn that the neutrino and the anti-neutrino are identical, a unique possibility among spin 1/2 particles. [Preview Abstract] |
Saturday, October 22, 2016 3:12PM - 3:48PM |
K1.00002: New Horizons explores the Pluto system Invited Speaker: John Spencer During its July 2015 flyby of Pluto and its five moons, the New Horizons mission obtained a wealth of data that has revolutionized our understanding of the Pluto system. Much of Pluto's outer shell of water ice is ancient and rigid, but much of the surface has been reworked, up to the present day, by a bewildering variety of geological processes. One hemisphere of Pluto is dominated by a feature unique (to our knowledge) in the solar system: a 1000 km wide field of actively convecting nitrogen and other ices occupying a large depression. Pluto’s surface color and composition is very varied, and is dominated by dark red tholins and N$_2$, CH$_4$, and CO ices, with H$_2$O ice bedrock also exposed in many places. Pluto’s hazy atmosphere, dominated by N$_2$ with a current surface pressure of 10 microbars, is supported by sublimation of the surface ices, and is much more tightly bound to the planet than expected before the flyby. Pluto’s giant moon Charon shows pervasive extensional tectonism and locally extensive cryovolcanic resurfacing, both dating from early in solar system history. Its color and surface composition, dominated by H$_2$O ice plus NH$_3$ hydrate, is remarkably uniform apart from a thin deposit of dark red material near the north pole which may be due to cold-trapping and radiolysis of hydrocarbons escaping from Pluto. Pluto’s four small moons, probably created from the debris of the giant collision that also formed Charon, exhibit complex rotational behavior unlike any seen elsewhere in the solar system. Unlike many icy satellites of the giant planets, neither Pluto nor Charon is likely to have experienced tidal heating during the period when observable landforms were created. Both objects therefore provide an important testbed for models of internal heating of icy worlds throughout the outer solar system. [Preview Abstract] |
Saturday, October 22, 2016 3:48PM - 4:30PM |
K1.00003: Student Awards and Farewell |
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