a BH is maximal.\
We think, the usual version of entanglement, we observe on the scales of ordinary quantum theory, is only an [epiphenomenon]{}, representing rather the coarse-grained effect of a hidden structure which lives on a much more microscopic scale. I.e., we are sceptical whether on such a microscopic scale the quantum vacuum can still be treated in the way of an ordinary quantum field theory vacuum as suggested in some of the papers cited above. We think, the [maximum-entropy property]{} of the BH-interior suggests another interpretation. We will come back to this point in more detail in section \[4\] (cf. also the sceptical remarks in some of the review papers by Wald, e.g. [@Wald1] (see in particular sect.6, Open Issues), [@W2] (see in particular sect.4, Some unresolved Issues and Puzzles\],[@W3]).

As BH-entropy is widely regarded as an observational window into the more hidden and primordial quantum underground of space-time, it should be expected that it can be naturally explained within the frameworks of the leading candidates of such a theory, i.e., to mention the most prominent, string theory or LQG. For certain extreme situations string theory manages to give an explanation of the BH-entropy-area law. Whether the explanation 