Differential Geometry and Partial Differential Equations

微分几何和偏微分方程

• 批准号: 1404966
• 负责人: Richard Schoen
• 金额: $ 30.45万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2015-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1404966&HistoricalAwards=false
• 关键词: Differential; Geometry; Partial; Equations

One aspect of the proposed research has to do with optimal shapes of surfaces. If we think of the surface as a drumhead which vibrates freely at certain frequencies, then, roughly speaking, the more complicated a geometry we have the smaller its fundamental frequencies will be. This suggests the problem of looking for geometries which maximize the fundamental frequency for their area. This extremal question is a difficult and much studied problem. It turns out that the geometries which arise are related to surfaces of least area (soap films). The proposer will investigate such extremal configurations for surfaces with boundary. The other main area of investigation concerns the Einstein equations of general relativity. These equations describe the gravitational field for massive bodies in the universe. The theory is purely geometric and is a wave theory with an initial value formulation. The proposer is planning to investigate the geometry of solutions to give conditions under which gravitational collapse takes place and black holes are formed. Such questions lead to important geometric questions involving gravitational energy and curvature of spacetime.The proposed research is at the interface between differential geometry, general relativity, and partial differential equations. A main theme of the research in geometry will be the study of spectral geometry. The PI plans to construct metrics on surfaces and certain higher dimensional manifolds subject to an area or boundary length constraint which maximize the first eigenvalue. This is a nonstandard type of variational problem since it involves maximizing and minimizing over infinite dimensional spaces of competitors. The PI will study the geometry of such maximizing metrics to determine the optimal shapes with largest fundamental frequency. In relativity, the PI intends to continue his investigations into the construction proposed by Bartnik of mass minimizing extensions of compact domains and static vacuum metrics. The PI also intends to study geometric properties of initial data sets concerning the question of whether they can contain non-compact stable trapped surfaces. Finally the PI intends to investigate global properties of the moduli space of solutions of the constraint equations which define the possible initial data for the Einstein equations. The PI shall pursue a range of questions concerning minimal submanifolds satisfying free boundary conditions and connections to eigenvalue problems. Finally the PI plans to continue his study of minimal lagrangian and special lagrangian submanifolds of Kahler-Einstein manifolds. The research will attempt to prove a conjecture concerning the invariance of the subgroup of the integral homology of a Calabi-Yau manifold which is generated by minimal lagrangian cycles when one deforms the ambient Calabi-Yau structure.

所提出的研究的一个方面与表面的最佳形状有关。如果我们把表面看作一个以特定频率自由振动的鼓面，那么，粗略地说，几何形状越复杂，它的基频就越小。这就提出了寻找使其面积的基频最大化的几何形状的问题。这个极值问题是一个困难的和许多研究的问题。事实证明，出现的几何形状与面积最小的表面（肥皂膜）有关。提议者将研究具有边界的表面的这种极端配置。另一个主要的研究领域是广义相对论的爱因斯坦方程。这些方程描述了宇宙中大质量物体的引力场。该理论是纯几何的，并且是具有初始值公式的波动理论。提议者计划研究解的几何形状，以给出引力坍缩发生和黑洞形成的条件。这些问题引出了涉及引力能和时空曲率的重要几何问题。拟议的研究处于微分几何、广义相对论和偏微分方程之间的界面。在几何学研究的一个主要主题将是光谱几何学的研究。PI计划在曲面和某些高维流形上构造度量，这些度量受面积或边界长度约束，使第一特征值最大化。这是一个非标准类型的变分问题，因为它涉及到最大化和最小化无限维空间的竞争对手。PI将研究这种最大化度量的几何形状，以确定具有最大基频的最佳形状。在相对论中，PI打算继续研究Bartnik提出的紧致域和静态真空度规的质量最小化扩展的构造。PI还打算研究初始数据集的几何性质，关于它们是否可以包含非紧稳定的捕获表面的问题。最后，PI打算调查的约束方程的解决方案，定义可能的初始数据的爱因斯坦方程的模空间的全局属性。PI应追求一系列的问题，关于满足自由边界条件的极小子流形和连接到特征值问题。最后PI计划继续他的研究最小拉格朗日和特殊拉格朗日子流形的卡勒-爱因斯坦流形。本研究将试图证明一个猜想，即当周围的Calabi-Yau结构变形时，由最小拉格朗日圈生成的Calabi-Yau流形的积分同调的子群的不变性。