# About entropy near black hole(decrease or increases)

1. Jul 20, 2011

### sairajagopal

The entropy of a black hole is one fourth of the area of the event horizon, so the entropy gets smaller and smaller as the black hole decays and the event horizon area becomes smaller and smaller.
If this is true I read that the black hole entropy is also the maximal entropy that can be obtained by the Bekenstein bound.

If the black hole entropy is maximum why do it decrease?...or

black hole's entropy when it decays it is maximum?

2. Jul 20, 2011

### LostConjugate

I think it decreases because space is expanding. I black hole should be the very last thing to decay in our universe, when space is reaching a thermal equilibrium and entropy is equal everywhere.

3. Jul 20, 2011

### Dr_Morbius

The entropy of the black hole depends on the surface area of the event horizon. The surface area of a black hole depends on it's mass. As the black hole decays it's mass goes down therefore it's surface area goes down therefore it's entropy goes down. The particles that are emitted during the decay carry away the entropy.

http://en.wikipedia.org/wiki/Black_hole#Entropy_and_thermodynamics