> On 13 Jul 2018, at 01:55, [email protected] wrote: > > > > On Wednesday, July 11, 2018 at 2:16:24 PM UTC-6, [email protected] wrote: > > > On Tuesday, July 10, 2018 at 4:42:44 PM UTC-6, Brent wrote: > > > On 7/10/2018 3:01 PM, [email protected] <> wrote: >> IIRC, the above quote is also in the Wiki article. It's not a coherent >> argument; not even an argument but an ASSERTION. Let's raise the level of >> discourse. It says we always get a or b, no intermediate result when the >> system is in a superposition of states A and B.. Nothing new here. Key >> question: why does this imply the system is in states A and B SIMULTANEOUSLY >> before the measurement? AG > > Because, in theory and in some cases in practice, there is a direct > measurement of the superposition state, call it C, such that you can directly > measure C and always get c, but when you have measured and confirmed the > system is in state c and then you measure A/B you get a or b at random. The > easiest example is SG measurements of sliver atom spin orientation where spin > UP can be measured left/right and get a LEFT or a RIGHT at random, but it can > be measured up/down and you always get UP. Any particular orientation can > be written as a superposition of two orthogonal states. > > When you're trying to explain esoteric issues to a moron in physics, you need > to be more explicit. These are the issues that cause confusion and caused me > to fail to "get it". After some subsequent posts, you seem to be saying that > in an SG spin experiment where the measurement base is UP/DN, the system > being measured is ALSO in a superposed LEFT/RIGHT state which is also > measured (by an SG device designed to measure spin?), and that the LEFT/RIGHT > superposed state persists with some persistent eigenvalue after UP/DN is > measured. It's murky for us morons. How does one get the system to be > measured in a superposition of RIGHT/LEFT; what is the operator for which > that superposition is an eigenstate, and what is the value of the persistent > eigenvalue? > > Furthermore, you finally assert that since the RIGHT/LEFT state persists -- > meaning that particle is in some DEFINITE state after the spin is measured -- > and since (as you finally, finally assert) that that state can be written as > a superposition of UP/DN, all is well -- in the sense that we can now be > certain that the system is physically and simultaneously in the UP and DN > states (which I am claiming is a fallacy). > > HOWEVER, assuming that I understand your argument after filing the gaps in > your presentation (and pointing to some unanswered issues), I now must "rant" > again that the UP/DN superposed representation is NOT unique. Thus, since > there are finitely many or uncountable many such representations, and since > (as per LC) QM has no preferred basis, your argument for the physical > simultaneity of UP and DN states fails. I mean, I could write the superposed > states in the basis (UP + DN) and (UP - DN), or in many other bases. Absent > uniqueness of bases, one cannot assert that the system is physically and > simultaneously in any particular pair of basis vectors. > > AG > > I've been looking over your references to Peres. CMIIAW, but AFAICT he > doesn't deal with the issue I have been "ranting" about; namely, the > non-uniqueness of bases, implying IMO that the concept of simultaneous > physical states of the components of a superposition is an additional, > unsupported assumption of QM which leads to some popular misconceptions of > what QM is telling us.
Then you need to find a new explanation of the interference that occurs in basically all quantum experiments, like the two slits, the statistics of results with Stern-Gerlach spin measuring apparatus, etc. The whole point of the physical wave amplitudes is that the diverse superposed components have a physical role, through destructive or constructive, or in between, interference. Note that the discussion here supposed the quantum theory, but you are free of course to propose an alternative. Many have tried without success, though. Bruno > Incidentally, when you earlier referred to a RIGHT/LEFT superposition, did > you mean circular polarization, or right and left directions in a SG > apparatus in relation to Up/Dn measurements? TIA, AG > > This is true in general. Any state can be written as a superposition of > states in some other basis. But it is not generally true that we can prepare > or directly measure a system in any given state. So those states we can't > directly access, we tend to think of them as existing only as superpositions > of states we can prepare. > > Brent > > -- > 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 post to this group, send email to [email protected] > <mailto:[email protected]>. > Visit this group at https://groups.google.com/group/everything-list > <https://groups.google.com/group/everything-list>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- 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 post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
