On Thu, Feb 26, 2015 at 10:33 PM, meekerdb <meeke...@verizon.net> wrote:
> On 2/26/2015 7:48 PM, Jason Resch wrote: > > > > On Thu, Feb 26, 2015 at 9:40 PM, Bruce Kellett <bhkell...@optusnet.com.au> > wrote: > >> Jason Resch wrote: >> >>> On Thu, Feb 26, 2015 at 9:20 PM, Bruce Kellett < >>> bhkell...@optusnet.com.au <mailto:bhkell...@optusnet.com.au>> wrote: >>> Jason Resch wrote: >>> >>> There's no problem defining probability. There is, however, a >>> big problem defining collapse. >>> >>> Collapse is easily defined. >>> >>> So at what point does it happen? >>> What triggers it? >>> On what scales can and can't it happen? >>> >> > The quantum bayesian answers are: When you learn the value. > When does that happen, and what defines/differentiates a learning being from any other physical encoding/state of the environment? > Your learning. > Is that when some neuron in my brain releases neuro-transmitters a instantaneous FTL collapse event propagates across the entire universe instantly destroying the superposition no matter how far away elements of it might be? Is everyone else besides me unable to collapse the wave function, or is it only me? If you're in a box with a radioactive particle and Geiger counter, do you remain in a superposition until I learn about your state (and cause a coherent and consistent version of you with memories of the past hour in a box to spontaneously come into existence)? > Not sure what "scales" refers to - probably any scale. > This was in reference to those who say the world is classical at some scales and quantum mechanical at other (small) scales, unlike MW which admits the universe operates quantum mechanically at all scales, always. > > How do you define a measurement? An observer? >>> How is a measuring apparatus or an observer different from any other >>> physical object? >>> What is the special property of the observer / measuring device that >>> enables it to collapse the wave function? >>> If you have an observer who himself is isolated from an external >>> environment, can he collapse the wave function? Or can only you collapse >>> him by observing him? >>> >> > Note that all these questions about "an observer" apply equally to "who is > the first person, that is indeterminate". > Questions about the first person are addressed by theories in philosophy of mind, not by quantum mechanics. Collapse on the other hand is supposedly a quantum mechanical phenomenon, not adequately explained or defined within the theory it is supposed to be a part of. Since collapse theories often connote special extra-physical abilities to the observer, it becomes natural to wonder in what ways an observer is physically different from other physical parts of the environment. Things are reversed under MW, which acknowledges no physical distinctions or powers exist between the particles that compose an observer, or any other particles or system. > > >> >> All these questions are rendered irrelevant if you take the view that the >> wave function is purely a device for calculating probabilities, > > > So it is easily defined, but when I ask what that definition is, I'm told > "shut up and calculate!" > > >> not something that has a real, independent existence. In other words, the >> epistemic interpretation of QM. > > > So then what was the universe before there were any observers? Did the > first mouse to be born and open its eyes cause the creation of the universe? > > > An epistemic interpretation and observation is updating a theory of the > world just like any other observation. Most theories of the world include > a past. > But would that past not be a gigantic uncollapsed wave function for the entire universe, since it had been evolving and splitting for aeons before anyone could learn anything? > > > >> There is nothing physical to collapse -- we are dealing solely with >> classical probabilities. >> > > If it's just a device for deriving probabilities, what is doing all the > work in a quantum computer? > > > Rotation of the state vector in Hilbert space. > > So it is real, and can do things even when not observed? 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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
