On 4/28/2022 4:48 AM, John Clark wrote:

On Tue, Apr 26, 2022 at 10:57 PM Bruce Kellett <bhkellet...@gmail.com>wrote:/> An important component of Everett's idea was that quantum evolution was unitary./Any idea that does not conform with quantum evolution being unitary isan idea that does not conform with experimental evidence and thus hasbeen proven to be incorrect.

`Measurement is, and always has been, described in quantum theory by`

`projection operators...which are not unitary. Without them there is`

`nothing in the theory to produce a result that can be compared to`

`empirical observation.`

Brent

/> If one wants to persist with unitary evolution, one cannot avoid the Schrodinger equation. This has a number of consequences for the theory. One is that the theory is deterministic -- there are no probabilities/No probabilities are needed from a Multiverse point of view, but forany observer in any particular universe

`In unitary evolution per the Schroedinger equation there are no`

`"paticular universes", there's only a ray in Hilbert space. Multiple`

`universes is a FAPP viewpoint. But so is wave-function collapse.`

there can only be probabilities because for them some information isunavailable, and that's what probabilities are all about, doing thebest you can with incomplete information.

`Probabilities are whatever measures satisfy Kologorov's axioms or their`

`logical equivalent. The information interpretation is QBism.`

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