On 2/12/2020 2:32 AM, Alan Grayson wrote:
On Tuesday, February 11, 2020 at 12:44:38 PM UTC-7, Brent wrote: On 2/10/2020 3:34 AM, Alan Grayson wrote:On Sunday, February 9, 2020 at 11:16:33 AM UTC-7, Brent wrote: On 2/9/2020 12:48 AM, smitra wrote: > On 08-02-2020 07:00, Bruce Kellett wrote: >> On Sat, Feb 8, 2020 at 4:21 PM smitra <[email protected]> wrote: >> >>> On 08-02-2020 05:19, Bruce Kellett wrote: >>> >>>> No, I am suggesting that Many-worlds is a failed theory, unable to >>>> account for everyday experience. A stochastic single-world theory >>> is >>>> perfectly able to account for what we see. >>>> >>>> Bruce >>> >>> Stochastic single word theories make predictions that violate those >>> of >>> quantum mechanics. >> >> No they don't. When have violations of the quantum predictions been >> observed? > > A single world theory must violate unitary time evolution, it has to > assume a violation of the Schrodinger equation. But there is no > experimental evidence for violations of the Schrodinger equation. Except for every measurement ever made of a quantum variable. Brent *But doesn't decoherence theory, which I recall you like, use unitary time evolution in an attempt to solve the measurement problem? Or did I misread you? AG *I think decoherence theory is a big step forward in describing the quantum->classical emergence. It was also a step forward in solving the measurment problem. But it has still left gaps. It shows how the density matrix becomes diagonalized in a measurement process. BUT only FAPP. And it doesn't explain why only one diagonal value is realized (MWI wants to keep them all) or the Born rule. I'm presently reading Ruth Kastner's book on the "Possibilist Transactional Interpretation" which is her version of Cramer's TI. Her basic idea, which could be applied to MW as well as TI, is that all the mathematical evolution takes place in possibility space, which is just as real as Hilbert space or wave-functions...but not as real as spacetime, and then one result, at random (and she justifies the Born rule) is actualized (which is a step better than realized). Metaphysically it is like MWI in practice, you calculate what happens in the many worlds and then you throw all but one away. The main difference is PTI depends on the idea of absorbers to define when a measurement is completed. The absorbers in a measurement are like the environment in decoherence, but there are also particle level absorbers...which I haven't finished reading about yet. BrentYou (and Bruce) are on the same page wrt unitary time evolution for the measurement process; namely, that it's violated. OTOH, you (and Bruce) like decoherence theory. According to Wiki, when the environment is included in the measurement process, the total process satisfies unitary time evolution, whereas the total process excluding the environment creates just the appearance of violating unitary time evolution. Is this your assessment; that unitary time evolution in the measurement process is satisfied when the environment is taken into account? TIA, AG
Unitary evolution is violated when specific outcomes occur. Decoherence only approximately diagonalizes the density matrix...in a specific basis. So it doesn't completely avoid the "collapse" problem.
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