On Tue, Aug 6, 2019 at 5:29 PM 'Brent Meeker' via Everything List < [email protected]> wrote:
> > > On 8/6/2019 11:25 AM, Philip Thrift wrote: > > > > On Tuesday, August 6, 2019 at 1:00:23 PM UTC-5, Brent wrote: >> >> >> >> On 8/6/2019 6:38 AM, Bruno Marchal wrote: >> >> If the QC does its task effectively, the output basis qbits will be put >> into definite states, >> >> >> Relatively to the observer, but in the global state, the observer will >> inherit the superposition state, by linearity of the tensor products and of >> the evolution. >> >> >> In something like Shor's algorithm there is only one final state with >> non-vanishing probability. Yet this is the kind of algorithm that Deutsch >> cites as proving there must be many worlds. >> >> Brent >> > > > > That there is a multiplicity of *somethings* > > https://en.wikipedia.org/wiki/Multiple_histories > > is the basis for all semantics of quantum computing (by computer > scientists) that I have ever seen. > > > Same for classical computation...there are lots of states or functions. > Did anyone think there had to be multiple worlds for the computer to work? > I think all of our disagreement comes down to the definition of world. If you define the world as the state of in some Hilbert space, you only need one such "WORLD". If you define world as a collection of interacting objects, that is itself causally isolated from other such "worlds" (for all practical purposes), then you get many of those, within the Hilbert space. This is made most clear in the case of a quantum computer. Where the quantum computer can be viewed as one WORLD (def 1) that contains many little worlds (def 2), where each computational trace constitutes its own little world, causally isolated from the rest. We would have no evidence those other traces even existed, except for the special cases we can arrange in the quantum computer to cause those many worlds to interfere with each other. (As is what's done in Shor's algorithm) Jason -- 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/CA%2BBCJUiafOi4p8UppOgtO6YejdsTdMs6P-oPk4aonLTgdVGtOg%40mail.gmail.com.
