Can black-hole entropy be quantized ?

Abstract

The remnant mass at the last stage of black hole evaporation is of the order of the Planck mass and the corresponding entropy is of the order of 2 πk B. On the basis of Bekenstein's work, I have derived that the minimum entropy increase when a black hole accretes matter is 2 πk B; this gives a lower bound of the Planck mass on the mass accretable by a black hole, which corresponds again to a minimum black hole entropy of the order of 2 πk B. Moreover, the minimum entropy and the minimum entropy increase are not affected by gravitation, hence the above statements also hold in the eraly universe. Hence I propose the conjecture that black hole entropy is qunatized with quantum 2 πk B.