Monday, February 23, 2015


It is not surprising to find that having knowledge of final conditions plus knowledge of initial conditions may tell us more than having knowledge of initial conditions alone. In a game of Russian roulette we might have initial conditions at time t0.  We might know that the cylinder was spun, the gun was pointed at the victim's head, and the trigger was pulled.  Given just these initial conditions we have a 5/6 chance of hearing a click and a 1/6 chance of hearing a bang at time t1. (t1 after t0)  But, given the added final condition that we know the victim is dead from gunshot wounds at time t2 (t2 after t1) we have increased the chance that a bang was recorded back at t1.  No retrocausation is implied.  To have retrocausation we want to be able to control the final condition at t2 (not just have a record of it) and cause a change at t1.

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