So, rookie question, I know, but I'm having a little trouble with the idea of wavefunction collapse as it pertains to stationary states:(adsbygoogle = window.adsbygoogle || []).push({});

If a measurement of energy collapses a wavefunction into an energy eigenstate, it stays there forever (unless perturbed). But my impression is that although position measurements collapse a wavefunction, the wavefunction will begin to evolve rather quickly after the measurement.

Does this have something to do with the fact that x doesn't commute with H? What are some other measurements that will yield an evolving wavefunction?

Say I have some operator associated with an observable that has two values: 'happy' and 'sad.' What else do I need to know about this situation to predict whether a measurement of 'happy' will leave the particle in that state for all time?

Thanks

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# Wavefunction collapse and measurement

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