WHAT WE DONT KNOW ABOUT BTZ BLACK-HOLE ENTROPY

With the recent discovery that many aspects of black hole thermodynami cs can be effectively reduced to problems in three spacetime dimension s, it has become increasingly important to understand the 'statistical mechanics' of the (2 + 1)-dimensional black hole of Banados, Teitelbo im, and Zanelli (BTZ). Several conformal field theoretic derivations o f the BTZ entropy exist. but none is completely satisfactory, and many questions remain open: there is no consensus as to what fields provid e the relevant degrees of freedom or where these excitations live. In this paper, I review some of the unresolved problems and suggest avenu es For their solution.