Ann Arbor and Copenhagen: Goudsmit, Heisenberg and BohrRudi Paul Lindner (History Department, University of Michigan)November 27, 2001During the Ann Arbor summer school of 1939 Samuel Goudsmit and others attempted to convince Werner Heisenberg to leave Germany. Heisenberg not only refused, but during World War II he played an active role in the German nuclear project. The drama Copenhagen, due to open in Detroit, reminds us of his equivocal position, as does a letter, soon to be released, that Niels Bohr wrote but did not mail after Heisenberg's famous visit to Copenhagen. This talk revisits Heisenberg's wartime role, Bohr's response, and Goudsmit's later reunion with his Ann Arbor guest. Black Holes in String TheoryFinn Larsen (University of Michigan)October 30, 2001Black holes exhibit thermal properties when quantum theory is taken into account. The microscopic structure responsible for this behavior is quite mysterious. Recent advances in string theory has led to dramatic progress on this problem. The colloquium is an account of this development intended for non-experts. M-Theory and the Brane WorldJames Liu (University of Michigan)April 24, 2001Much recent attention has been paid to the idea that our 3+1 dimensional universe may turn out to be a brane embedded in a higher-dimensional spacetime. In such brane world models, the extra dimensions are often assumed to be large and possibly even infinite in extent. In contrast, string theory, which for a long time has embraced extra dimensions, has traditionally taken them to be extremely small and unobservable. However the two cases are not as far apart as they may appear on the surface, as M-theory provides a basis for realizing large extra dimensions. I will first review some of the background of extra dimensions in M-theory and then explore possible connections between M-theory and the brane world. Stochastic RatchetsCharles Doering (University of Michigan, Math Dept.)March 7, 2001A ratchet is a device that can rectify nondirectional forces. In this talk we will discuss some elementary models of ratchets capable of rectifying statistically isotropic noise into directional motion. We'll describe some applications of these ideas in mesoscopic condensed matter physics and molecular biology, and discuss some (perhaps) unexpected features of the simplest models. |

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