How Does Black Hole Entropy Increase When Starting with a Pure State?

[touqra]

Supposing I started off with a particle, which I know exactly the state it is in, hence, it is in a pure state. And hence also, its entropy is zero.
Now, suppose we throw the particle into the black hole and be sucked in, then, then the area of the black hole increases and hence, the entropy of the black hole also increases.
But, how can this be possible? I started off with a zero von Neumann entropy and why should the entropy/area of the black hole increase?

 

[mathman]

In most physical processes entropy increase, so why are you surprised?

 

[MTyler8]

Try starting here:

http://en.wikipedia.org/wiki/Black_hole_entropy

 

[whiteholes]

according to the 2nd law of thermodynamic, entropy cannot decrease..decreasing the chance of a white hole possiblility.

 

[hellfire]

If you started with a pure state, entropy increase is only possible if you allow for a violation of unitary time evolution. This problem is known as black hole information loss and points out an incompatibility between QM and GR.

 

[whiteholes]

but i thought there is a theory that states that information cannot be lost or destoyed?

 

[hellfire]

but i thought there is a theory that states that information cannot be lost or destoyed?

Information is lost in irreversible macroscopic processes. I think that the statement is that unitary time evolution of pure quantum states is a principle that should not be violated. In case of quantum field theory of black holes, it's violation is an indication that something is wrong in the theory. If you are interested in knowing more about this I would suggest to ask in the subforum "Beyond the Standard Model".