Expanded afternoon edition — September 20, 2026.
For The Black Hole War, a concrete route into holography starts with counting states. Doubling a region’s width multiplies its volume by eight but its boundary area by four. Black-hole entropy follows the latter scaling. Trying to pack unlimited independent information into a volume eventually encounters gravity: adding enough energy makes a black hole.
Susskind’s 1994 The World as a Hologram explores a lower-dimensional description capable of encoding the apparent bulk. The surprising economy concerns independent degrees of freedom. The word “hologram” can distract by suggesting that we should go looking for a projector. Original paper
Maldacena’s later work supplied a concrete route to studying such dualities in specially structured theoretical spacetimes. Extending the idea to our own cosmological setting remains harder. Information can also be preserved in correlations while becoming fantastically impractical to reconstruct; preservation and recoverability ask different questions. Maldacena’s original proposal