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SUMMARY:Geometry and Topology in Gravitational Lensing - Marcus Werner\, I
 nstitute of Astronomy\, Cambridge
DTSTART:20090522T120000Z
DTEND:20090522T130000Z
UID:TALK18566@talks.cam.ac.uk
CONTACT:Dr H K Kunduri
DESCRIPTION:Gravitational lensing is a thriving research field at the inte
 rface of\nastrophysics and theoretical physics. In this talk\, I will disc
 uss some\napplications of geometry and topology to gravitational lensing t
 heory in the\nlimit of small deflection angles\, using the optical metric 
 and the impulse\napproximation. It will be shown how the Gauss-Bonnet theo
 rem offers a global\nperspective of lensing different from the usual treat
 ment\, and how Morse\ntheory can be used to constrain image numbers. A new
  interpretation of\nmagnification invariants in terms of Lefschetz fixed p
 oint theory will also\nbe presented.
LOCATION:Pavilion B Potter Room (B1.19)
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