A Retrocausal Interpretation of Classical Collision Between Rigid Bodies

Abstract

When two bodies collide with each other, they change their motion. Many physics textbooks explain that the change in motion iscausedby the force or impulse exerted on the body during the collision. This is not the whole story, I argue, in case the bodies arerigid. In this case, the change in motion cannot be causally explained solely by how the bodies are configured before and during the collision but instead should be explained partly by what happens after the collision. That is, the collision between rigid bodies should better be interpreted as a case ofretrocausationwhere the future causally affects the past or present. This retrocausal interpretation of the collision does not suffer a general problem raised against retrocausation, known as thebilkingargument. And how the influence of the cause propagates backward in time to the effect in the collision is no more mysterious than how a body moves continuously in classical mechanics or how the future affects the past in proposed retrocausal models for the EPR thought experiment in quantum mechanics.