interesting stuff.
i'm not sure of the mapping from boundary/event horizon (neither of which is an obvious term) around black holes to a notion of hologram...but this is probably more a function of just running into this area of work than anything about the area of work.
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edit: this site is quite helpful in laying out the basic terminologies and ways of thinking through them that are involved with this project:
http://www.einstein-online.info/en/index.html
the sections on general relativity are the most relevant.
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seems to me that on a more banal level, something like a hologram idea follows from color, that it "isn't" what we perceive it as being, that we translate light spectra in ways that are consistent enough for there to "be" color, even though in a sense it isn't there outside our shared perceptual apparatus. apparently.