2017
Jun
08

# Colloquium: Vadim Kaloshin (Maryland) - "Birkhoff Conjecture for convex planar billiards and deformational spectral rigidity of planar domains"

2:30pm to 3:30pm

## Location:

Manchester Building (Hall 2), Hebrew University Jerusalem

G.D.Birkhoff introduced a mathematical billiard inside of a convex domain as the motion

of a massless particle with elastic reflection at the boundary. A theorem of Poncelet says

that the billiard inside an ellipse is integrable, in the sense that the neighborhood of the

boundary is foliated by smooth closed curves and each billiard orbit near the boundary

is tangent to one and only one such curve (in this particular case, a confocal ellipse).

A famous conjecture by Birkhoff claims that ellipses are the only domains with this

of a massless particle with elastic reflection at the boundary. A theorem of Poncelet says

that the billiard inside an ellipse is integrable, in the sense that the neighborhood of the

boundary is foliated by smooth closed curves and each billiard orbit near the boundary

is tangent to one and only one such curve (in this particular case, a confocal ellipse).

A famous conjecture by Birkhoff claims that ellipses are the only domains with this