Spectral Problems in Geometry and Partial Differential Equations

点击翻译按钮获取中文摘要

This project will focus on three areas of spectral theory for partial differential equations: (1) resonances in geometric scattering, (2) harmonic analysis on two-step nilpotent Lie groups, and (3) inverse spectral methods in the theory of nonlinear dispersive equations. In the first project, the principle investigator will continue his work on spectral and scattering theory for asymptotically hyperbolic manifolds and complex manifolds, studying properties of scattering resonances and their relationship to underlying geometric invariants. In the second project, he will work toward understanding the asymptotic behavior of heat kernels and singularities of the wave trace for two-step nilpotent Lie groups. Nonlinear dispersive equations with singular initial data may be viewed, via the inverse scattering method, as linearized flows for the scattering data of a very singular potential. We hope to extend the inverse scattering picture for the KdV and mKdV equations to such singular data and obtain greater insight into these dynamical systems--by constructing the flow on Hilbert spaces of initial data which are singular but very natural from a dynamical point of view.Partial differential equations provide underlying mathematical models for such diverse physical phenomena as wave propagation and heat flow. An equally important part of any physical model is the geometry of the system it describes: for example, differently-shaped musical instruments produce sound waves with different frequencies, even though in all cases the production and propagation of waves is governed by the same differential equation. The first two projects above study the interaction between solutions of a certain partial differential equation and the geometry of the domain where the solutions are defined, and seek to relate quantifiable properties of the solutions to quantifiable properties of the underlying geometry. These projects are part of a larger effort in the mathematical community to understand "inverse problems" in which the geometry of a physical system is reconstructed from measurable data which are the solutions of a partial differential equation: seismology and medical imaging are among the areas of applied mathematics where such inverse problems occur. The third project is a contribution to the study of a class of equations arising in physics which describe the propagation of nonlinear waves by extending powerful solution methods to a richer set of data.