Acad Sinica, Inst High Energy Phys, Beijing 100039, Peoples R China
Global geometric properties of dS space are presented explicitly in various coordinates. A Robertson-Walker-like metric is deduced, which is convenient to be used in the study of dynamics in dS space. Singularities of wave functions of massive scalar fields at boundary are demonstrated. A bulk-boundary propagator is constructed by making use of the solutions of equations of motion. The dS/CFT correspondence and the Strominger mass bound is shown.