@vzn From you know where from today:
"As a student of John Wheeler's, Hugh Everett III wrote the thesis, The Theory of the Universal Wavefunction, in 1956. A year later, in 1957, Review of Modern Physics published the version Relative State Formulation of Quantum Mechanics.
These texts are mixtures of wrong statements and trivialities. The main wrong statements are that "the wave function is an objectively real, observer-independent, and therefore 'universal' set of classical degrees of freedom" and that "it doesn't ever collapse".
"As a student of John Wheeler's, Hugh Everett III wrote the thesis, The Theory of the Universal Wavefunction, in 1956. A year later, in 1957, Review of Modern Physics published the version Relative State Formulation of Quantum Mechanics.
These texts are mixtures of wrong statements and trivialities. The main wrong statements are that "the wave function is an objectively real, observer-independent, and therefore 'universal' set of classical degrees of freedom" and that "it doesn't ever collapse".
In addition to Joshphysics' precise answer, let's mention another interpretation (the one I think Ben Crowell is referring to in his comment to the same answer).
There's a formula from time dependent perturbation theory which gives the probability of an induced transition from an initial state $...
Special relativity has four-vectors $(\Delta t,\Delta \mathbf{r})$ and $(E,\mathbf{p})$, so we would like there to be a direct analogy between these two uncertainty relations. In fact the analogy fails, because position is an operator in quantum mechanics, but time isn't. Peierls has a nice discu...
It is said, that when measured, a quantum system undergoes "wave function collapse", which is a non-unitary transformation.
Why?
The wave function is
$\Psi = \alpha \left|0\right\rangle + \beta \left|1\right\rangle$
where
$\left|\alpha\right|^2 + \left|\beta\right|^2 = 1$
The probabilities...
