The Forgetful Black Hole: Memory Burden and Hysteresis in Hawking Evaporation

Abstract

The memory-burden scenario of black hole evaporation proposes that Hawking emission may become increasingly suppressed as maintaining stored quantum information becomes dynamically costly. In this work, we revisit this scenario and investigate the conditions under which information retention can produce a genuine dynamical burden. We derive general scaling conditions for incremental memory accumulation at a fixed fractional mass loss and establish a conditional no-go result: entropy-suppressed, zero-mean deposits with subextensive integrated correlations cannot produce an order-one luminosity modification through unamplified accumulation and bounded feedback. We identify three essential requirements for dynamical memory: a record of the past must be written, retained, and coupled back to subsequent evaporation. We illustrate these requirements with concrete toy models that exhibit either a prolonged but finite black hole lifetime or an asymptotically approached finite-mass state (an effective remnant). We further distinguish kinetic-memory, thermodynamic-memory, and spectral-memory sub-categories of possible memory-burden mechanisms. In particular, we demonstrate that an independently evolving memory variable can generate evaporation-accretion hysteresis, such that a black hole returning to the same mass may possess a different retained memory and consequently a different luminosity. This history dependence may have implications for primordial black hole phenomenology. Finally, we briefly discuss the possibility of "merger rejuvenation", in which black hole mergers reorganize or reset the effective memory state.