# Holographic principle and Wheeler's bag of gold

How is it possible to explain "bag of gold" spacetimes (see Marlof) such that the ideas are compatible with AdS/CFT and the holographic principle?

• Perhaps explain 'bag of gold' a little bit! – Andersi2 Feb 18 '14 at 14:43
• There's a review in Black Holes, AdS, and CFTs. I think your question is too broad to be usefully addressed here. – John Rennie Feb 18 '14 at 15:49
• @JohnRennie do you know enough about the issue such that you can meaningfully judge if the question is too broad or not ...? To me it rather seems that for an expert or any person knowledgeable about the topic, this questions asking if a certain kind of spacetime is compatible with holography / AdS/CFT can easily be answered form a physics point of view. We should not get biased in our judgement by other earlier questions of the same OP ;-), this one seems perfectly well defined. – Dilaton Feb 18 '14 at 16:29
• so were the others ;) – user33923 Feb 18 '14 at 16:41
• but that's what I think... I know enough to see there are lots of holes in string theory and holography... that doesn't mean I am not interested in expert-opinions or at least in other people's opinions... for example today I ended up remembering about the bag of gold spacetimes after a discussion with Mitchell Porter who asked me to find an example of solution of Einstein equations that disagrees with holography. Chance made it that this info came into my mind precisely when I needed it for some other serious work I am doing. So, I am interested in interesting opinions. – user33923 Feb 18 '14 at 17:20

A recent paper has the following proposal on the nature of the interior excitations: excitations in the interior placed however far apart from each other are not really independent excitations but two such seemingly independent excitations in semiclassical gravity in the bulk $$AdS$$ side have extremely small inner products between them, which can be seen from the $$CFT$$ side. Thus even if there are a huge number of interior excitations, the Bekenstein Hawking entropy correctly calculates the dimension of the Hilbert space of the black hole, and semiclassical excitations in the interior live in this Hilbert space in an overcomplete basis. Treatment of these semiclassical states as independent is what leads to the overcounting and consequently, the apparent violation of Bekenstein Hawking entropy.