On Monday, October 15, 2018 at 11:17:56 AM UTC, Bruce wrote: > > From: <[email protected] <javascript:>> > > > On Sunday, October 14, 2018 at 5:08:42 PM UTC, smitra wrote: >> >> On 14-10-2018 15:24, [email protected] wrote: >> > In a two state system, such as a qubit, what forces the interpretation >> > that the system is in both states simultaneously before measurement, >> > versus the interpretation that we just don't what state it's in before >> > measurement? Is the latter interpretation equivalent to Einstein >> > Realism? And if so, is this the interpretation allegedly falsified by >> > Bell experiments? AG >> >> It is indeed inconsistent with QM itself as Bell has shown. Experiments >> have later demonstrated that the Bell inequalities are violated in >> precisely the way predicted by QM. This then rules out local hidden >> variables, therefore the information about the outcome of a measurement >> is not already present locally in the environment. >> >> Saibal >> > > What puzzles me is this; why would the Founders assume that a system in a > superposition is in all component states simultaneously -- contradicting > the intuitive appeal of Einstein realism -- when that assumption is not > used in calculating probabilities (since the component states are > orthogonal)? AG > > > I think the problem arises with thinking of a superposition as an > expression of a fact of the system being in all components of the > superposition simultaneously. This mistaken interpretation leads to the > Schrödinger cat paradox, which you have worried about for a while. > > But this is a mistake. A superposition is just an expansion of a wave > function in some basis or the other -- the choice of basis is arbitrary, so > it makes no sense to think of this expansion as representing anything that > happens in "reality" (in Einstein's sense of "reality"). The state is still > the original state until decoherence kicks in >
*Here's where I think you're mistaken. When the box is closed in the Cat experiment, time continues to increase, so the wf evolves independent of decoherence; before it sets in; before it takes effect, however short that duration might be. But since the expansion of the superposition is arbitrary wrt the basis used in the expansion, it still makes no sense to attribute any physical reality to it, much less a simultaneous state of all components. Do agree with this? TIA, AG* > and then, because of einselection of a preferred basis, we can say that > the separate states are "real" -- namely orthogonal, so that one other > other is chosen. Until that time, the only state around is the original > state, as can be demonstrated by the possibility of recoherence, in which > case you recover just the initial state and nothing else. > *I can see how recoherence is impossible FAPP, but after some time elapses the state of the cat could Dead or Alive; not necessarily the original state, Alive. A*G > > So for Schrödinger's cat, for example, if you could recohere the system > after one hour, say, you would find the cat alive in the box and the vial > of cyanide unbroken with the radioactive atom undecayed -- exactly as you > set the system up. It is only because the cat and apparatus are large warm > classical objects that this recoherence is not possible FAPP. To think of > the cat at some intermediate time as being both dead and alive is just a > confusion -- it is at all times either one or the other. > *The Cat does have an intermediate state since time is evolving causing the wf to evolve, but as I argue above, it's not in both states of the superposition because the choice of basis is arbitrary, and by extension, certainly not in both states simultaneously. I generally agree with your arguments, which I articulated half-a-dozen times or more last summer, but no one here seemed to understand or agree. When you remind us that the choice of basis is arbitrary, this is KEY, and all one has to do is apply what's anathema to see the seminal error; common sense applied to the fact that the basis used in the superposition is arbitrary! It seems there remains an undeserved impulse, a cottage industry as it were, to claim some mysteries in QM that don't exist. AG * > > Bruce > -- 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.
