> you the experimentalist have a soul and when that soul measures the world the nice unitary evolution of the world comes crashing down with probabilities given

> you the experimentalist have a soul and when that soul measures the world the nice unitary evolution of the world comes crashing down with probabilities given by the Born rule. There's a great paper by van Kampen[1] that points out that what we call a measurement and collapse of the wave function is entangling a quantum state to an irreversible statistical process. Measurement and wave function collapse are limit cases of that that are useful approximations when doing calculations. [1]: http://www.johnboccio.com/research/quantum/notes/vankampen.pdf http://www.johnboccio.com/research/quantum/notes/vankampen.p... (a version sans paywall!)