Op zondag 3 april 2016 23:33:21 UTC+2 schreef Steven Carlip:

We believe that matter in a pure quantum state can collapse
to form a black hole.
This is in a certain sense equivalent that a star collapses and becomes
a neutron star
Such a black hole will then evaporate
by Hawking radiation, which is thermal.
This is in a certain sense equivalent that a star explodes and
becomes a super novae.
The issue is if in either of these cases you can speak about
information loss?
To answer the questions you must have a clear definition of what
information means and what a pure and mixed quantum states are.
To start with the second, my interpretation of a pure quantum state
is that an object as such is completely everywhere physical
and chemical identical. They have no structure.
The four important parmeters a Radius, Volume, Mass and density.
In a pure quantum state object the density is everywhere the same.
My interpretation of a mixed state is that it has a structure.
For example in the Sun and in planets when you "travel" towards
the center the density changes.

When the density and chemical composition inside a BH is everywhere
the same than the information content is zero compared to the encyclopedia
britanica. The text of a book contains knowledge and information.
Along that line when you burn a book it is information loss.

IMO it is much more important to understand the intial conditions and
the whole life cycle process of a Black Hole until his dead.
I doubt if the concept of information is in anyway important in order
to understand this physical process.

When the black hole has completely evaporated,

The issue is here how do we know that BH physical can evaporate and
change into a gaseous (visible?) state.

The problem only
appears quantum mechanically, when you allow black holes
to evaporate thermally via Hawking radiation.

The problem is much more a physical, chemical problem.
At the same time it is also an information problem in the sense that
we cannot directly observe a BH. That means it is extremely difficult
to observe that the life cycle time of a BH is finite.
It is a murder without a body. For a star this is much simpler.

Nicolaas Vroom