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Paul Danaher wrote: > Eugene Stefanovich wrote: > >>... There is no mystery in the instantaneous "wavefunction collapse". >>Wavefunction is just a probability density >>amplitude. Its collapse is not associated with any physical process. >>If you lost your key and don't know where it is, there >>is (a small but non-zero) chance that your key is on $\alpha$ Centauri. >>As soon as you find you key in the pocket, this probability >>instantaneously reduces to zero. > > This seems to be a strong version of the Copenhagen interpretation $- we$ > can't talk about a process, only about events (i.e. observations). Let me stress that my interpretation of QM is different from the Copenhagen interpretation. Copenhagen says that before the measurement the system is "really" in the state which is a linear combination of different possibilities. The state of one individual system is described by the wave function. When the measurement is made, the wavefunction "collapses". The observable didn't have a certain value before the measurement. The definite value of observable "emerges" as a result of measurement. In my interpretation, the system did have a certain value of observable before the measurement was done. We simply don't know what this value is, and we have no means to predict this value. The wavefunction does not describe the individual system. It simply describes our knowledge (or lack of it) about the system. When the measurement is done, we simply observe the value of observable which was already there. There is no "collapse" of probabilities. At least, there is no more "collapse" than in my above example for the probability of finding the key on $\Alpha$ Centauri. > Doesn't > this logically lead to Vecchi's position in the "No new Einstein" thread, > which seems to be at variance with your own position there? As far as I can understand, Vecchi's position is different from mine. > > Experiments like the micromaser experiments at the Max-Planck-Institut seem > to me to imply the possibility of getting a distribution for the interval > between excitation and emission, where half the minimum interval would be an > upper bound for "the time taken to emit one photon", no? I am not sure which experiment you are talking about. Could you give some references? Eugene.