Black Holes, Interactions, and Strings
  We give some examples in which neglecting the interactions between particles or truncating the description of a black hole to the spherically symmetric mode leads to unphysical results. The restoration of the interactions and higher angular momentum modes resolves these problems. It is argued that mathematical consistency of the description of black holes in the Schwarzschild coordinate system requires that we neither truncate the theory nor ignore the interactions. We present two hypotheses on how matter must behave under large Lorentz boosts in order for black holes to be consistent with quantum mechanics. Finally, we argue that string theory exhibits these properties. Talk presented at the PASCOS meeting in Syracuse, New York, May 1994. 
L. Susskind and J. Uglum