Residual Memory After Hypothetical Timeline Modification: A Falsifiable Framework Linking Collective False Memory, Causal Revision and Time-Travel Paradoxes

Backward time travel raises a basic problem of causality: if an event in the past is modified, what becomes of the future that motivated the intervention? Standard treatments invoke self-consistency, branching histories, chronology protection or quantum models of closed timelike curves. This paper develops a different speculative framework, motivated by the popular phenomenon known as the Mandela Effect, in which many people share specific memories that conflict with the documented record. The Residual Memory Hypothesis (RMH) considers a universe in which modifying a past event replaces the subsequent history with a new, causally consistent one. Physical records and nearly all observers then carry information consistent only with the revised history. One additional postulate allows a small fraction of observers to retain information encoded under the superseded history. Inside the revised timeline, such residual memories would look like false memories and would resemble the Mandela Effect. Psychology already explains shared false memories through reconstruction, semantic association, misinformation and social transmission, so the Mandela Effect is not evidence of timeline modification. To make the proposal testable, the paper (i) formalises RMH within a two-dimensional ("hypertime") model of change, which shows that a residual memory requires a discontinuity in the ordinary-time evolution of the brain that carries it; (ii) derives predictions that separate RMH from conventional memory models, chiefly synchronised onset, independence from social exposure, low semantic predictability and prospectively documented switches from accurate to identical non-canonical recall; and (iii) specifies a preregistered longitudinal protocol whose null result would place a quantitative bound on the hypothesis. The framework takes no position on whether backward time travel is physically possible and presents no evidence that history has been altered.