  These notions in the title are of fundamental importance in any branch of
physics. However, there have been great difficulties in finding physically
acceptable definitions of them in general relativity since Einstein's time. I
shall explain these difficulties and progresses that have been made. In
particular, I shall introduce new definitions of center of mass and angular
momentum at both the quasi-local and total levels, which are derived from first
principles in general relativity and by the method of geometric analysis. With
these new definitions, the classical formula p=mv is shown to be consistent
with Einstein's field equation for the first time. This paper is based on joint
work [14][15] with Po-Ning Chen and Shing-Tung Yau.
