On Wed, Aug 7, 2019 at 7:39 PM Bruno Marchal <[email protected]> wrote:
> On 7 Aug 2019, at 02:19, Bruce Kellett <[email protected]> wrote: > > On Wed, Aug 7, 2019 at 10:04 AM smitra <[email protected]> wrote: > >> On 07-08-2019 00:45, Bruce Kellett wrote: >> >> > The trouble with that argument is that in any simulation, you get to >> > set the rules of physics that obtain. There is then no guarantee that >> > the results of your simulation have any relation to physics in the >> > real (unassimilated) world. For decoherence to work, all that is >> > required is a sufficient number of environmental degrees of freedom >> > for multiple copies of the result to be recorded by the "environment >> > as witness", in Zurek's words. Quantum Darwinism then ensures that the >> > result is permanent and irreversible. >> >> If you measure the z-component of a spin polarized in the x-direction, >> then however astronomically large the number of environmental degrees of >> freedom there are that get entangled with the spin, it's still a finite >> number. One minute after the measurement all the degrees of freedom that >> can be entangled are within one light-minute of the experimental set-up. >> So, the recording of the result in the environment are going to be a >> superposition of the two possible recordings. >> > > It is called the "relative state" interpretation for a reason. The > entanglement with the environmental degrees of freedom that leads to the > recording of the result in the environment is relative to each possible > experimental outcome. Within the decoherence time (typically of the order > of a few nanoseconds or less) these "relative states" become effectively > orthogonal, and the measurement becomes irreversible. Because there is no > longer any possibility of interference between the results, there is no > longer any superposition. > > > > That does not follow. There is no more a possibility to detect the > interference. > What exactly is the difference between something that it is impossible in principle to detect and something that does not exist? > That does not make the other terms of the wave vanishing, they become just > inaccessible, or … you introduce something non linear in QM. > > You guys seems so desperate to hold on to a superposition that no longer > has any practical consequences. > > Yes, because we are not interested in practical matter, but in conceptual > understanding. > Conceptual understanding of what? Things that do not exist? > Get used to it -- measurements have definite outcomes. That is the fact > that has to be incorporated into your theory. > > > That’s like coming back to collapse, if not to 'shut up and calculate', > frankly. > No, it is recognising the reality that the theory is designed to describe and predict. Bruce -- 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLT4%2BARSoPQEwUmckXuNgwZgCT4iA2_FFh11d924j%3DMcrA%40mail.gmail.com.
