Anticausality

Anticausality is a term used in physics and philosophy to describe a causal relationship in which effects can influence prior conditions, i.e., causal influence travels from future to past. It is not the standard direction of causation in everyday experience, which runs from past to future, but it appears in time-symmetric formulations of physical theories and in discussions of retrocausality.

In physics, anticausality often arises in models that treat time on an equal footing, allowing both advanced and retarded interactions. The Wheeler–Feynman absorber theory, for example, uses both future and past potentials; under suitable boundary conditions, the theory is effectively causal in the macroscopic sense while incorporating anticipatory influences at the fundamental level.

But we should be careful: such theories typically do not allow signalling backwards in time and are constructed to be consistent with observed causality. In quantum mechanics, some retrocausal interpretations (or the two-state vector formalism) consider influences that propagate backward in time in a time-symmetric way, but still prohibit faster-than-light communication.

Philosophically, anticausality raises questions about the nature of causation, time, and the arrow of time grounded in entropy. Critics argue that it conflicts with everyday causal intuition and with thermodynamic asymmetry, while proponents view it as a potential way to reconcile quantum nonlocal correlations with relativistic causality.

See also: retrocausality, time symmetry, Wheeler–Feynman theory, two-state vector formalism.