Past Colloquia

21 October 2005
16:30
Abstract
The recent developments of Mathematical Physics have brought very new ideas about the nature of space . I will argue that we have to mix the methods of noncommutative geometry of Alain Connes with the prophetic views of Grothendieck about the so-called motives and their motivic Galois group .<br> The dream of a &quot;cosmic Galois group&quot; may soon become an established reality .<br> &nbsp;
10 June 2005
16:30
Abstract
I will give an expository account of Mathai, Melrose, and Singer [math.DG/0402329], explaining how to define the projective Dirac &quot;operator&quot; when the underlying manifold is neither spin nor spin_C, and how to define its analytic index which need not be an integer. Nevertheless, the usual index formulas apply. <i>Professor Singer will be admitted as honorary member of the London Mathematical Society just before his talk.</i>
28 May 2004
16:30
Nigel Hitchin
Abstract
Einstein bequeathed many things to differential geometry &mdash; a global viewpoint and the urge to find new structures beyond Riemannian geometry in particular. Nevertheless, his gravitational equations and the role of the Ricci tensor remain the ones most closely associated with his name and the subject of much current research. In the Riemannian context they make contact in specific instances with a wide range of mathematics both analytical and geometrical. The talk will attempt to show how diverse parts of mathematics, past and present, have contributed to solving the Einstein equations.

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