Bielefeld Graduate School in Theoretical Sciences

Prof. Jean-Philippe Bouchaud (École polytechnique) :

Tipping points and crises: from statistical physics to macroeconomic modelling

16:15, lecture hall H10

Abstract:
Using the methodology of statistical physics, which characterizes a model through its ``phase diagram", we explore the possible types of phenomena that ``agent-based" macroeconomic models with interactions, frictions and heterogeneities can reproduce.
Through this looking glass, we will discuss three stylized models (interacting firms networks, agent based models of firms and households and dynamical trust networks). In each case one finds generic phase transitions (or tipping points) between a ``good economy" state where unemployment/volatility are low and confidence is high, and a ``bad economy" state where unemployment/volatility are high and confidence is low.
If the parameters are such that the system is close to such transitions, any small fluctuation may be amplified, leading to a large level of endogenous volatility. This can cause the monetary policy itself to trigger instabilities and be counter-productive. We identify several theoretical scenarios for synchronization and instabilities in large economies that can generate aggregate volatility and acute crises without any identifiable idiosyncratic shocks. This suggests an interesting explanation for the unexpected outbursts of endogenous economic or financial crises, also known as the ``small shocks, large business cycles" puzzle.

Prof. Dr. Jan Plefka (Humboldt University of Berlin):

The world as a hologram: News from String Theory

16:15, lecture hall H6

Abstract:
We are all familiar with holograms: Two dimensional optical structures which - when suitably lit - create the
illusion of a three-dimensional object. In fact the light waves emerging from holograms are identical to the ones one would preceive from
the three-dimensional object - a distant observer cannot distinguish the two. Recent research in fundamental physics has revealed
that the gravitational force of nature might in fact be a holographic illusion in this sense. It is replacable by a lower dimensional structure,
known as gauge field theory. The latter is the theoretical framework to describe all the non-gravitational forces in nature which reign elementary
particle physics. Our lecture will begin with reviewing the basic concepts of gravitation, quantum mechanics and quantum fields. Then the holographic
concept and its relation to superstrings will be presented. Finally, current insights on how to exploit this duality to answer questions
in gauge field theory, which had not been accessible so far, will be presented.

Prof. Eiichiro Komatsu (Max-Planck-Institute for Astrophysics):

Critical Tests of Theory of the Early Universe using the Cosmic Microwave Background

16:15, lecture hall H6

Abstract:
The Cosmic Microwave Background (CMB), the fossil light of the Big Bang, is the oldest light that one can ever hope to observe in our Universe. The CMB provides us with a direct image of the Universe when it was still an “infant” - 380,000 years old - and has enabled us to obtain a wealth of cosmological information, such as the composition, age, geometry, and history of the Universe. Yet, can we go further and learn about the primordial universe, when it was much younger than 380,000 years old, perhaps as young as a tiny fraction of a second? If so, this gives us a hope to test competing theories about the origin of the Universe at ultra high energies. In this talk I present the results from the Wilkinson Microwave Anisotropy Probe (WMAP) satellite that I contributed, and then discuss the recent results from the Planck satellite (in which I am not involved). Finally, I discuss future prospects on our quest to probe the physical condition of the very early Universe

Prof. Dr. Ulrich Horst (Humboldt University of Berlin ):

Optimal Order Display in Limit Order Markets,

18:15, lecture hall H8

Prof. Chris Shannon (University of California, Berkeley):

Risk, Uncertainty and Ambiuity in Markets,

16:15, seminar room V2.210

PD Dr. Ulf Hashagen (Forschungsinstitut für Technik- und Wissenschaftsgeschichte, Deutsches Museum München):

Kein Platz für das "Genie": Der ungarisch-jüdische Mathematiker Johann von Neumann in Deutschland,

16:15, lecture hall H6

- The BGTS opening ceremony took place on
**2 November 2012**at 4 pm in the lecture hall H2, Bielefeld University.

- The joint workshop of the planned Bielefeld Graduate School in Theoretical Sciences (BGTS) was held on
**February 14th and 15th, 2011**at**Hotel Klosterpforte, Marienfeld**.