In this paper we first show that within the Hamiltonian description of
general relativity, the central charge of a near horizon asymptotic symmetry
group is zero, and therefore that the entropy of the system cannot be estimated
using Cardy's formula. This is done by mapping a static black hole to a two
dimensional space. We explain how such a charge can only appear to a static
observer who chooses to stay permanently outside the black hole. Then an
alternative argument is given for the presence of a universal central charge.
Finally we suggest an effective quantum theory on the horizon that is
compatible with the thermodynamics behaviour of the black hole.Comment: 16 pages, no figures, LaTex 2e, references adde