What are the options for adding built-in black hole information retrieval systems?

The question of how information might be retrieved from a black hole through a built-in mechanism challenges our fundamental understanding of physics. Currently, no practical engineering solutions exist; the options are purely theoretical frameworks emerging from the intersection of quantum mechanics and general relativity. One prominent option is the holographic principle, which suggests all information within a black hole's volume is encoded on its two-dimensional event horizon. A built-in retrieval system, in this view, would involve decoding this holographic data. Another avenue is found in quantum gravity models, like string theory or loop quantum gravity, which propose a radical revision of spacetime at the singularity. These theories speculate that information might be preserved in a Planck-scale remnant or "fuzzball," where it remains inherently accessible in a modified form. A third, more indirect option involves Hawking radiation. If this radiation is not purely thermal but contains subtle quantum correlations—a process known as unitarity—then the information slowly leaks out. A built-in system would then be an advanced decoder of this emitted radiation. Finally, some modified spacetime geometry proposals, such as "firewalls" or exotic wormholes (ER=EPR conjecture), imply internal structures that could, in principle, store and potentially allow retrieval of information. These options are not mutually exclusive but represent different mathematical approaches to resolving the black hole information paradox. Their common thread is the necessity to move beyond classical physics, suggesting any true built-in retrieval system would be an inherent feature of a yet-to-be-discovered quantum theory of gravity.