Extracting the bulk metric from boundary information in asymptotically AdS spacetimes

We use geodesic probes to recover the entire bulk metric in certainasymptotically AdS spacetimes. Given a spectrum of null geodesic endpoints onthe boundary, we describe two remarkably simple methods for recovering the bulkinformation. After examining the issues which affect their application inpractice, we highlight a significant advantage one has over the other from acomputational point of view, and give some illustrative examples. We go on toconsider spacetimes where the methods cannot be used to recover the completebulk metric, and demonstrate how much information can be recovered in thesecases.Comment: 33 pages, 11 figures; v2 references adde