Prof. dr. Gunther Cornelissen (UU) will give a lecture (in English) on how empirical observations (e.g. sound) can uniquely determine an underlying object.

Drinks afterwards!

****ABSTRACT****

Isospectrality and what to do about it.
“Isospectrality” is the problem that Mark Kac popularised by coining the phrase “Can you hear the shape of a drum?”. We describe sound and light (and basically any outcome of a physical experiment) as the spectrum of some operator. But that spectrum does not always determine the underlying object uniquely. I will describe the history of the problem, starting in the 1920’s with Hendrik Lorentz and one of his students; analogies in number theory, and some more recent developments that try to come to grips with this problem.