Landauer Saturation in Hawking Evaporation and an Information and Energy Accounting Framework

Building on Cortês and Liddle's demonstration that Hawking evaporation saturates the Landauer bound, we develop an information and energy accounting framework for black hole thermodynamics. The exact identity T_H S_BH = ½ Mc² for Schwarzschild black holes is an exact scaling relation. We treat the ½ factor as an interpretive bookkeeping device rather than a rigorous energy decomposition, and use it to organize an information/field-cost accounting language. We derive this factor of ½ from first principles via the first law of black hole thermodynamics and the holographic scaling S ∝ M². The framework positions black holes as the thermodynamic complement to quantum measurement: measurement creates classical information by paying Landauer costs, while black holes destroy classical information and return those costs as Hawking radiation. We propose consistency checks testable in analog gravity systems and discuss implications for the information paradox.