Posted: Feb 02, 2011 12:06 pm
by Darkchilde
Rilx wrote:"Observation" means that the observer detects the observed by "touching" it with some system which changes its energy state. If the observed itself radiates some detectable energy, you don't need to "touch" it, but the radiation itself changes it's energy state.

Thought experiments have their pitfalls, always.

No, until a measurement is performed, according to the Copenhagen interpretation, we do not know to which probability the wavefunction will collapse to. There is no meaning in saying that the energy state will change, because we may not know what that state is accurately, as we have the Heisenberg Uncertainty Principle and one of the pairs of variables is energy/time.

So, we may measure the energy of a quantum system accurately, but we will not know when that measurement applies to!

As I said, the Copenhagen interpretation talks about measurement, but it does not define what that measurement is. There is no definite energy or other state associated with a quantum system, only probabilities, until the measurement is performed.

Twistor, other than energy/time and position/momentum, are there any other pairs of variables that we cannot measure both accurately, as per the Heisenberg Uncertainty Principle?