A single photon approaches a polarization filter. It's orientation is described by a probability amplitude wave function. It is not reflected or absorbed, but passes through the filter. Now it's orientation immediately after is definitely known. Question 1: is there no information/enthalpy gain/loss in this event? Question 2: it seems that this event could not be time reversible. We can not have an event where a photon of orientation known to be the same as the filter, passes through and becomes a photon of unknown orientation.