There has long been a dispute among philosophers about whether causation must by definition work only from the past, and some argue that there is no reason in principle why causation should not work from the future as well. Some science fiction writers have explored possible paradoxes caused by causation from the future, and in general there is a cloud of confusion over this whole area. Many of the equations of physics are reversible and some interpretations of quantum mechanics allow for influences to pass backwards in time. For example in Richard Feynman's interpretations of quantum mechanics a positron can be regarded as an electron moving backwards in time.

In John Cramer's transactional interpretation of quantum mechanics when a photon is emitted from the sun and takes 8 minutes before it is absorbed by something on earth, the absorber on earth sends a reverse signal to the emitter on the sun 8 minutes before the photon from the sun strikes the absorber. There is a kind of 'handshake' between the emitter and the absorber. Retrocausation takes on a practical significance in trying to interpret evidence for precognition, which is relatively common in dreams, and also for presentiment or "feeling the future."


Recommended Book

Quantum Retrocausation: Theory and Experiment (AIP Conference Proceedings)

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