1Department of Physics, Institute of Theoretical Physics, Beijing Normal University, Beijing 100875 2CCAST (World Laboratory), PO Box 8730, Beijing 100080
Applying the generalized uncertainty relation to the calculation of the free energy and entropy of a Reissner-Nordstrom black hole inside the brick wall, the entropy proportional to the horizon area is derived from the contribution of the vicinity of the horizon. This is compared with the entropy calculated via the original brick wall model. The entropy given by the original brick wall model comes from the outside of the brick wall seemingly. The inside result using generalized uncertainty relation is similar to the outside result using original uncertainty relation, and the divergence inside the brick wall disappears. It is apparent that the cutoff is something related to the quantum theory of gravity.