On Saturday, July 7, 2018 at 12:19:23 PM UTC-6, agrays...@gmail.com wrote: > > > > On Friday, July 6, 2018 at 1:56:12 PM UTC-6, agrays...@gmail.com wrote: >> >> >> >> On Friday, July 6, 2018 at 1:22:03 PM UTC-6, Brent wrote: >>> >>> >>> >>> On 7/6/2018 11:44 AM, agrays...@gmail.com wrote: >>> >>> >>> >>> On Thursday, July 5, 2018 at 5:14:34 PM UTC-6, Brent wrote: >>>> >>>> >>>> >>>> On 7/5/2018 3:55 PM, agrays...@gmail.com wrote: >>>> >>>> >>>> >>>> On Thursday, July 5, 2018 at 2:03:46 PM UTC-6, Brent wrote: >>>>> >>>>> >>>>> >>>>> On 7/5/2018 11:27 AM, agrays...@gmail.com wrote: >>>>> >>>>> >>>>> >>>>> On Wednesday, July 4, 2018 at 10:57:06 AM UTC-6, Brent wrote: >>>>>> >>>>>> >>>>>> >>>>>> On 7/4/2018 1:57 AM, 'scerir' via Everything List wrote: >>>>>> >>>>>> >>>>>> *No. I am asserting that the INTERPRETATION of the superposition of >>>>>> states is wrong. Although I have asked several times, no one here seems >>>>>> able to offer a plausible justification for interpreting that a system >>>>>> in a >>>>>> superposition of states, is physically in all states of the >>>>>> superposition >>>>>> SIMULTANEOUSLY before the system is measured. If we go back to those >>>>>> little >>>>>> pointing things, you will see there exists an infinite uncountable set >>>>>> of >>>>>> basis vectors for any vector in that linear vector space. For quantum >>>>>> systems, there is no unique basis, and in many cases also infinitely >>>>>> many >>>>>> bases, So IMO, the interpretation is not justified. AG* >>>>>> >>>>>> ***SIMULTANEOUSLY*** was used by EPR in their paper, but that did not >>>>>> have much meaning (operationally, physically). >>>>>> >>>>>> Can we say that the observable, in a superposition state, has a >>>>>> ***DEFINITE*** value between two measurements? >>>>>> >>>>>> No - in general - we cannot say that. >>>>>> >>>>>> >>>>>> It's in some definite state. But it may be a state for which we have >>>>>> no measurement operator or don't intend to measure; so we say it is in a >>>>>> superposition, meaning a superposition of the eigenstates we're going to >>>>>> measure. So it does not have one of the eigenvalues of our measurement. >>>>>> >>>>>> Brent >>>>>> >>>>> >>>>> *So for the radioactive source, the superposed state, Decayed + >>>>> Undecayed, does NOT imply the system is in both states simultaneously? * >>>>> >>>>> >>>>> No, it is in a state that consists of Decayed+Undecayed. So in a >>>>> sense it is in both simulatnaeously. If you are sailing a heading of >>>>> 45deg >>>>> you are on a definite heading. But you are simultaneously traveling >>>>> North >>>>> and East. And if someone was watching you with a radar that could only >>>>> output "moving north" or "moving east" it would oscillate between the two >>>>> and you might call that a superposition of north and east motion. >>>>> >>>>> Brent >>>>> >>>> >>>> *I see. But as I have pointed out, there are uncountably many sets of >>>> basis vectors that result in the same vector along the 45 deg direction. >>>> Thus, it makes no sense to single out a particular basis and claim it is >>>> simultaneously in both. * >>>> >>>> >>>> That's where you're wrong. It makes perfect sense if that's the only >>>> basis you can measure in. That's why I gave the hypothetical example of a >>>> radar that could only report motion as northward or eastward. In some >>>> cases, like decayed our not-decayed, we don't have instruments to measure >>>> the superposition state. In other cases like sliver atom spin we can >>>> measure up/down or left/right or along any other axis. >>>> >>>> *ISTM, this is the cause of many of the apparent paradoxes in QM such >>>> as Schroedinger's cat, or a radioactive source which is decayed and >>>> undecayed simultaneously. I have no objection using such a state to do a >>>> calculation, but I think it's an error to further interpret a >>>> superposition >>>> in terms of simultaneity of component states. What say you? AG* >>>> >>>> >>>> I say use what's convenient for calculation. Don't imagine your >>>> calculation is the reality. >>>> >>> >>> >>> *But the consensus, perhaps unstated or subliminally, is that the >>> superposition is imagined as reality, which leads to cats and radioactive >>> sources being (respectively) alive and dead, and decayed and undecayed, >>> simultaneously. Isn't this what Schroedinger was arguing against? I have >>> rarely, if ever, seen it argued NOT to interpret a superposition as reality >>> as a proposed solution to these apparent paradoxes. AG * >>> >>> >>> You just go around and around. You never put together the explanations >>> you get. Decoherence shows that, in the presence of an environment, the >>> wave function FAPP collapses into orthogonal quasi-classical states in >>> fractions of a nano-second. That's why the Schroedinger cat story doesn't >>> show what Schroedinger thought it did. BUT there are experiments, like >>> silver atoms thru and SG in which superpositions of left+right persist, >>> they are up polarizations for example; and we know they exist because we >>> can prepare up states and then measure them left/right or measure them >>> up/down. The latter, up/down measurement, would always yield "up" showing >>> they were in an up eigenstate, even though they were also in a left+right >>> superposition. But there are other cases where we can't measure the >>> eigenstate (e.g. neutrino family) so we always describe them as being in a >>> superposition because the eigenstate is operationally unmeasurable and we >>> can't prepare them in an eigenstate. >>> >>> Brent >>> >> >> *You also go round and round without answering a key question about >> decoherence theory. You refer to the infinitesimally short decoherence time >> of, say, the apparatus, but ISTM it has already decohered way before it is >> employed in any experiment. What then is the reasoning for including the >> apparatus in the superposition for the entire system, and claiming this wf >> represents the total system before any environmental interaction? BTW, what >> is a right + left superposition in SG measurement, and how is it relevant >> to this discussion? TIA, AG * >> >> *(My computer is being repaired, so I have limited library time for >> possibly a week or more. This means I will have to study some of your >> examples later before possibly responding.)* >> > > *Thinking about this some more, I agree that if one measures in a > particular basis, it is natural to express the wf of the system in a > superposition of this basis. However, where I disagree with your analysis > is that one doesn't need decoherence theory to resolve Schroedinger's > apparent cat paradox. This is because regardless of the natural basis used, > there is nothing in QM to allow, or compel us to interpret the > superposition as meaning the system is simultaneously in all component > states (which interpretation seems to produce an alleged paradox). > Moreover, although we cannot measure in other bases, the wf can > nevertheless be expressed in other bases, and sometimes the set of bases is > uncountable, again casting doubt on the legitimacy of interpreting the > superposition in terms of simultaneity of component states. Do you agree or > disagree? * > > *Also, when doing an SG spin measurement, I don't see that right-left is > well defined for a well-defined Up / Dn measurement. I also don't see why > the system is assumed to be in a superposition of right + left, or why it > persists after the measurement, or in what way these facts -- if they are > facts -- is in any way enlightening. I would appreciate your comments on > these issues. * > > *TIA, AG* >
*From Wiki; **https://en.wikipedia.org/wiki/Quantum_superposition* *The principle of quantum superposition states that if a physical system may be in one of many configurations—arrangements of particles or fields—then the most general state is a combination of all of these possibilities, where the amount in each configuration is specified by a complex number <https://en.wikipedia.org/wiki/Complex_number>.* *For example, if there are two configurations labelled by 0 and 1, the most general state would be* [image: c_0 \mid 0 \rangle + c_1 \mid 1 \rangle] <https://wikimedia.org/api/rest_v1/media/math/render/svg/ea1f5b5eb7f306860452f691348db266bc303dd9>{\displaystyle c_{0}\mid 0\rangle +c_{1}\mid 1\rangle } *where the coefficients are complex numbers describing how much goes into each configuration.* *The principle was described by Paul Dirac <https://en.wikipedia.org/wiki/Paul_Dirac> as follows:* *The general principle of superposition of quantum mechanics applies to the states [that are theoretically possible without mutual interference or contradiction] ... of any one dynamical system. It requires us to assume that between these states there exist peculiar relationships such that whenever the system is definitely in one state we can consider it as being partly in each of two or more other states. The original state must be regarded as the result of a kind of superposition of the two or more new states, in a way that cannot be conceived on classical ideas. Any state may be considered as the result of a superposition of two or more other states, and indeed in an infinite number of ways. Conversely any two or more states may be superposed to give a new state... (underlining my emphasis)* *IMO, he's mistaken. There's no need for the underlined assumption. If anyone here disagrees, please offer your *argument*. TIA, AG* >>> >>> >>>> Brent >>>> >>>> >>>>> *Same for cat, Alive + Dead? Same for ( (Undecayed, Alive) + >>>>> (Decayed, Dead) ) for Schroedinger's composite system? If that's the >>>>> case, >>>>> why would anyone think these states are in any way paradoxical or >>>>> contradictory? AG* >>>>> -- >>>>> 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-li...@googlegroups.com. >>>>> To post to this group, send email to everyth...@googlegroups.com. >>>>> Visit this group at https://groups.google.com/group/everything-list. >>>>> For more options, visit 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 everything-li...@googlegroups.com. >>>> To post to this group, send email to everyth...@googlegroups.com. >>>> Visit this group at https://groups.google.com/group/everything-list. >>>> For more options, visit 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 everything-li...@googlegroups.com. >>> To post to this group, send email to everyth...@googlegroups.com. >>> Visit this group at https://groups.google.com/group/everything-list. >>> For more options, visit 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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
