 CARMA ANALYSIS AND NUMBER THEORY SEMINAR
 Speaker: ARC Laureate Fellow George Willis, CARMA, The University of Newcastle
 Title: Naive Noncommutative Geometry
 Location: Room V206, Mathematics Building (Callaghan Campus) The University of Newcastle
 Time and Date: 3:00 pm, Tue, 18^{th} Oct 2011
 Abstract:
Noncommutative geometry is based on fairly sophisticated methods: noncommutative C*algebras are called noncommutative topological spaces, noncommutative von Neumann algebras are noncommutative measure spaces, and Hopf algebras and homological invariants describe the geometry.
Standard topology, on the other hand, is based on naive intuitions about discontinuity: a continuous function is one whose graph does not have any gaps, and cutting and gluing are used to analyse and reconstruct geometrical objects. This intuition does not carry over to the noncommutative theory, and the dictum from quantum mechanics that it does not make sense any more to think about point particles perhaps explains a lack of expectation that it should.
The talk will describe an attempt to make this transfer by computing the polar decompositions of certain operators in the group C*algebras of free groups. The computation involves some identities and evaluations of integrals that might interest the audience, and the polar decomposition may be interpreted as a noncommutative version of the double angle formula familiar from high school geometry.
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