On 5/8/2022 1:50 PM, smitra wrote:

On 08-05-2022 06:03, Brent Meeker wrote:On 5/7/2022 6:21 PM, smitra wrote:On 05-05-2022 00:04, Brent Meeker wrote: On 5/4/2022 12:27 PM, smitra wrote: In fact, that idea introduces a raft of problems of its own -- what is the measure over this infinity of branches? What does it mean to partition infinity in the ratio of 0.9:0.1? What is the mechanism (necessarily outside the Schrodinger equation) that achieves this? That simply means that there is as of yet no good model for QM without the Born rule.But there is no mechanism for the Born rule. It is inconsistent with pure Schroedinger evolution of the wave function. I think the problem of measures on infinity is overcome if you simply postulate a very large but finite number of branches to split. Or why not not an continuum probability and just measure by the density around the eigenvalue...the measured values are never exact anyway. I don't these things are wrong or show MWI is inconsistent, but I think they show it has just moved the problems it purported to solve off to some unobservable worlds, which is no better than CI. Born rule is not inconsistent with the Schrödinger equation, it just tells you that the wavefunction gives you the probability amplitudes. This is better than the CI, because the CI is inconsistent with the Schrödinger equation. Because?? It takes one more step and says "probability means something happens and other things don't." It's not called the "Copenhagen Equation". It's called the "Copenhagen Interpretation", i.e. how to _INTERPRET_ the Schroedinger equation and so it is consistent with it.It's called an interpretation just like the MWI, but these areactually different theories that make different predictions, albeit ina domain that cannot easily be accessed experimentally.That the CI is inconsistent with the Schrödinger equation is easy tosee. If the Schrödinger is valid, then the state of a system evolvesin a unitary way. But after a real collapse the state changes in anon-unitary way.

`Which is only a problem if one insists that the Schroedinger equation is`

`the whole of the theory and it is ontic. CI denies the first and says`

`that measurements are projection operators because a measurements is`

`necessarily a classical-like result. QBism says the whole theory is`

`epistemic.`

If we consider measuring the z-component of a spin polarized in thex-direction using a Stern-Gerlach apparatus, then the entire systemof the spin the experimental set-up, the observer and localenvironment consists of particles that should evolve according to theSchrödinger equation.

"Should"?

If the measurement takes one minute, then the initial state of a patchof one light-minute diameter around the location of the experimentmaps to a final state of that patch in a unitary way.

`You seem to overlook that this one-light minute sphere also had incoming`

`particles and radiation which could not be accounted for the`

`Schroedinger equation.`

But CI says that this does not happen because the internal observer inthe system performed a measurement that causes the state of the systemto collapse.

`Yes, that's a problem although CI+decoherence doesn't depend on an`

`observer. The effect of the incoming radiation is also a problem. But`

`MWI doesn't solve the problem, it just assumes that the correlations are`

`created which have the same effect as collapse as far as the instruments`

`and observers are concerned. Decoherence goes part way to solving the`

`problem by quantifying how the "collapse" occurs statistically in time.`

Brent

The issues with branches etc. are likely just artifacts with making hidden assumptions about branches. At the end of the day there are only a finite number of states an observer can be in. If an observer is modeled as an algorithm, take e.g. Star Trek's Mr. Data then it's clear that there are only a finite number of bitstrings that can correspond to the set of all possible things Mr. Data can be aware of.But different Mr. Data's and different instruments can have different number of states. So what you're suggesting is QBism.It may fall under QBism, the question is if this is going to causeproblems that cannot be resolved well.SaibalBrent -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To view this discussion on the web visithttps://groups.google.com/d/msgid/everything-list/cdb187f5-6770-7216-a03f-75fca3b0c4c7%40gmail.com[1]. Links: ------ [1]https://groups.google.com/d/msgid/everything-list/cdb187f5-6770-7216-a03f-75fca3b0c4c7%40gmail.com?utm_medium=email&utm_source=footer

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