And can a collapsed wavefunction be retreived?
Once the wave function has collapsed, it is gone, and the hisotry of the particle begins anew from whatever physical state the previous wave collapsed to.
There is no natural lifetime for a wave function. They are conceived as going along until something causes a collapse. This is all assuming the wave function is something physical, which is a doubtful assumption.
You might as well ask how long is a piece of string?
Actually saying that in GRW there is a finite proabilty of a wavefunction collapsing into a localized stae at any time, but GRW theory's hardly popular, mainly due to the fact that experimental evidence seems to disagree with it.
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