Events at Physics
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Events on Tuesday, October 28th, 2014
- PUBLIC ASTRONOMY WHITFORD LECTURE
- Heart of Darkness
- Time: 12:00 pm
- Place: 145 BIRGE HALL
- Speaker: Jeremiah Ostriker, Columbia Universty
- Abstract: Can we unravel the secrets to of the universe and construct a scientific model that is believable? Over the past forty years, we have learned that two little-understood components--dark matter and dark energy--comprise most of the known cosmos, explain the growth of all cosmic structure, and hold the key to the universe's fate. The first of these accelerates the collapse of over-dense lumps and the formation of cosmic structures while the second pushes apart the structures that have formed.
From our early attempts to comprehend the solar system, to current space based exploration of our own galaxy and the realm of the nebulae beyond, to the detection of the primordial fluctuations of energy from which all subsequent structure developed, we will try to both explain the physics and also the history of how the current model of our universe arose and has passed every test hurled at it by the skeptics. Throughout this story, an essential theme is emphasized: how three aspects of rational inquiry--the application of direct measurement and observation, the introduction of mathematical modeling, and the requirement that hypotheses should be testable and verifiable--guide scientific progress and underpin our modern cosmological paradigm. While the resulting model “works” to great precision, it still leaves unanswered some of the most fundamental cosmic questions. We know that a cosmic model with more dark matter than ordinary chemical elements and even more dark energy than dark matter works well – ie matches all of the facts – but we do not know the nature of these dominant dark components.
- Host: Dept of Astronomy
- Chaos & Complex Systems Seminar
- On reactive model-free stock trading in a complex financial market
- Time: 12:05 pm
- Place: 4274 Chamberlin Hall (Refreshments will be served)
- Speaker: Bob Barmish, UW Department of Electrical and Computer Engineering
- Abstract: In this seminar, I will describe a new paradigm for stock trading in a complex financial market. The theory does not make use of a predictive model for the time-varying stock price. Instead, based on the use of a feedback control loop, the investment level is dynamically adjusted over time via a "reactive adaptation'' mechanism. In the finance literature, such a scheme falls under the umbrella of "technical analysis.'' After explaining what is meant by technical analysis, I will address a long standing conundrum in finance: Why is it that so many asset managers, hedge funds and individual investors trade stock using technical analysis despite the existence of a significant body of literature claiming that such methods are of questionable worth with little or no theoretical rationale? Whereas existing work on this question by academics and practitioners in finance involves extensive statistical analysis of a trading algorithm via back-testing with historical data, our new feedback-based approach is aimed at providing a theoretical rationale which explains both successes and failures.
- Host: Clint Sprott
- Theory Seminar (High Energy/Cosmology)
- Galactic Center Gamma-ray Excess from a Dark Shower
- Time: 3:00 pm
- Place: 5280 Chamberlin Hall
- Speaker: Dean Robinson, University of California, Berkeley
- Abstract: The reported excess of gamma-rays, emitted from an extended region around the galactic center, has a distribution and rate suggestive of an origin in dark matter (DM) annihilations. However, the conventional annihilation channels into standard model (SM) b quarks or tau leptons may be in tension with various experimental constraints on antiproton and positron fluxes. We'll discuss a framework that is free from such constraints. The key idea is that the mediators between the dark matter and the SM are themselves part of a strongly coupled sector. DM annihilation produces a dark hadron shower that in turn decays to photons, but without other significant associated cosmic ray production. We'll also discuss an explicit realization of this framework and its phenomenology.
- Host: Ran Lu