From Stephen Moran
Patrick Barry’s article describes John Cramer’s proposed experiment to delay one of two entangled particles by sending it on a longer journey than its twin, then forcing the delayed particle to choose wave or particle form in order to find out if the choice forced upon it controls the form of the twin particle, detected earlier (30 September, p 36). If you think this through, it turns out that either the delayed particle has the same form as its partner, in which case you cannot say that the past has not controlled the future, or the delayed one has a different form, in which case you cannot say that the future has controlled the past.
The proposed experiment has even farther-reaching implications than described. If it shows a retrocausal effect, it will also show that quantum entanglement only affects the photons and not the whole experiment.
My prediction is that there will be no measured retrocausal effect because the whole experiment is in quantum superposition. This means that changing the movable detector changes the state of the experiment, so the photon arriving at the other detector matches the current measurement, not the measurement that was taking place when the photon beam was split.
