The most famous question in the subject of spectral geometry is "Can you hear the shape of a drum?" In this talk we will show how to obtain the differential equation which describes a vibrating string, drum, or higher dimensional space. This differential equation involves the Laplace operator on the space. If you listen to the note a musical instrument makes, you hear the dominant pitch of the note, but sometimes also the "overtones" which have higher pitches. The sound that an object makes is actually composed of several notes of different pitches. The pitches in the note correspond to the eigenvalues of the Laplace operator. The matheamtical question "Can you hear the shape of a drum?" means: "If you know the eigenvalues of the Laplace operator on a space, can you say what shape the space is?" We will explain how you can "hear" a number of properties such as the total area or volume of the space, and the number of holes it has, and whether it is round.
Penn Undergraduate Mathematics Colloquium
Wednesday, March 14, 2007 - 4:30pm
Kate Okikiolu
University of Pennsylvania