> On 5 Nov 2019, at 01:23, Lawrence Crowell <[email protected]> > wrote: > > On Sunday, November 3, 2019 at 4:17:28 PM UTC-6, Brent wrote: > > > On 11/3/2019 10:43 AM, Philip Thrift wrote: >> In order for this statement to be useful, we need to solve the preferred >> basis problem. For example, consider the mathematical identity >> >> |u a w> + |e d c> = |n+ s+ f+> + |n+ s- f-> + |n- s+ f-> + |n- s- f+> (2) >> >> where >> >> |n+> = |u> + |e>, |n-> = |u> - |e> >> |s+> = |a> + |d>, |s-> = |a> - |d>, >> |f+> = |w> + |c>, |f-> = |w> - |c>. >> >> Unless we introduce a further piece of interpretive apparatus, we are in >> danger of supposing that the system described by |phi> is also described by >> |n+ s+ f+> or each of the other components in (2), which would mean we have >> not solved the original problem. However, this is easily solved, as follows: >> Postulate 1. A quantum system and environment described by the state |phi> >> is also described by one of the states of the basis in which the reduced >> density matrix of |phi> is diagonal after the environment has been traced >> over. >> The `collapse' from |phi> to one of |u a w> and |e d c> is now no different >> from the abrupt change in a classical probability distribution when more >> information becomes available. > > At this point one is then tempted to ask why not just say the wf collapsed? > Tracing over the environment is already something the experimenter does on > paper. It's not part of the Schroedinger equation unitary evolution. Sure > it makes the off-diagonal terms small...but it doesn't make them zero. It's > still just FAPP. > > > Brent > > In effect at this point it is much the same as with decoherence where a > density matrix is reduced to diagaonals and it is a classical probability > "collapse.”
… and that describes a first person plural appearance, like we need when we assume Digital Mechanism or Computationalism. Bruno > > LC > > -- > 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] > <mailto:[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/4b05b819-2c7e-4890-aa3a-117b683d46d1%40googlegroups.com > > <https://groups.google.com/d/msgid/everything-list/4b05b819-2c7e-4890-aa3a-117b683d46d1%40googlegroups.com?utm_medium=email&utm_source=footer>. -- 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/C8047445-1D02-41C5-AA9A-72D4BB31F168%40ulb.ac.be.
