Quantum mechanical measurement (schrodinger's cat)-

[mritunjay]

1. Suppose in Schrödinger cat thought experiment we place a camera inside the chamber which record the events happening inside the chamber. (We are not watching inside the chamber through the camera during the period of experiment. It is just for recording purpose). After one half life of decaying material, we don’t know the state of the cat since we have not yet opened the chamber. For us, cat is in the superposed state of ‘alive’ and ‘dead’. As soon as we look inside the chamber, we make the wave function collapse to one definite state. Now, we take the camera out and watch the events which took place inside the chamber. By watching through the camera, we now know the state of the cat (and hence system) for the whole period of experiment. Hence, for whole period of experiment, we know the state of the system.
a. Tell me, how this is compatible with standard Copenhagen interpretation that we can’t know the state of the system (here cat) unless we have done the measurement.
b. In this modified thought experiment we know the state of the system even if we have not yet observed the system (though we know corresponding state not at present but only in future). Does it mean that our act of measurement in future is causing the wave function to collapse in past. (But it will also mean that recording of camera in past is dependent on our observation in future).
c. Or, we should think that camera is capable of collapse of wave function and we don’t need a conscious observer for it.

 

[DrClaude]

Consciousness is never necessary to to the concept of measurement in quantum mechanics. In this particular case, the environment is measuring the state of the cat long before anyone opens to box.