Quote:
Originally Posted by multiweb
I don't understand the logic in there. I understand that the action of measuring sometimes disturbs the state of what you are measuring but if the observer is not doing anything and is not there, then what's the difference?  |
The logic is simple:
For example, to measure the position of the electron, we have to use some sort of measuring gauge.. and precision one.
The light comes to mind.. and to achieve the precision, we have to use short wavelengths... that means high energy photons.
When the electron disperses the photon, we know exactly where it was.. but we have no idea where it is now after measurement of position and in which direction it flew away.
If we use low energy photons, the momentum after measurement will be known.. but the position will be very uncertain.
Those two parameters, momentum and position are intimately connected via Plank constant.. and we simply can not know both values at the same time with arbitrary precision (Heisenberg principle of uncertainty).
This is what is meant by observer's influence on object of measurement.