报告题目：二维时空中的"细长因果集"面积计算 (The area of a long skinny interval in two-dimensional spacetime)
报 告 人：王依力 研究生(英国帝国理工学院物理系)
报告时间：2017年10月12日（周四）14:00
报告地点：校本部G309
邀请人：葛先辉
报告摘要：
考虑在类光费米坐标中，用一条长度为$\tau$的类时测地线将时空中的两点相连，文章计算了"细长因果集"在二维情况下的面积，同时也给出了类时测地线的好参数的表达式。我们发现因果集的面积与沿着因果集的类光测地线的空间曲率有关，同时也给出了因果集体积在四维时空中可能的表达式。（In this paper, the `long skinny interval' problem is studied. The two endpoints of a causal diamond are joined by a timelike geodesic which has a proper length of $\tau$. The work is done in Null Fermi Normal Coordinate system in two-dimensional spacetime and the expression for the area of a long skinny interval is found. We will first find the affine parameter along a timelike geodesic and then write the area in terms of $\tau$. It turns out that the corrections of the area depend on the curvature along the geodesic, which is exactly what one should expect. The form that the volume might take in four-dimensional spacetime is also given）。
