On Tuesday, February 9, 2021 at 11:31:31 AM UTC-7 Brent wrote:
> > > On 2/9/2021 2:46 AM, Alan Grayson wrote: > > > > On Tuesday, February 9, 2021 at 12:13:37 AM UTC-7 Brent wrote: > >> >> >> On 2/8/2021 9:31 PM, Alan Grayson wrote: >> >> >> >> On Monday, February 8, 2021 at 9:22:29 PM UTC-7 Brent wrote: >> >>> >>> >>> On 2/8/2021 7:50 PM, Alan Grayson wrote: >>> >>> *More important, I don't think your comment relates to what I wrote >>>> immediately above in RED -- which is consistent with Bohr's view that a >>>> system is NOT in any specific eigenstate before measurement* >>>> >>>> >>>> I don't know the quote from Bohr, but I suspect it's leaving out the >>>> context that the system is not in an eigenstate *of the variable >>>> measured* before it is measured. That just means the state NE is not >>>> North or East before you measure with your North-or-East instrument. >>>> >>>> Brent >>>> >>> >>> *I wasn't quoting Bohr, but I assume that Bohr (and the CI) assert, that >>> a system in a superposition of states is NOT in any of the eigenstates of >>> the superposition "of the variable measured before it is measured". * >>> >>> >>> What is your idea of not being in any eigenstates of the superpositon? >>> It the state if of a silver atom spin is LEFT it is not in an eigenstate of >>> UP or DN because if you measure it in the UP/DN basis you'll get half UP >>> and half DN. But it is in a superposition of |UP>+|DN> >>> >>> >>> *IOW, before measurement, the system is NOT objectively in any states of >>> the variable being measured; aka no objective properties prior to >>> measurement. But this flies directly in the face of the repeated claim by >>> the usual suspects, professional and otherwise, that the system is in ALL >>> states simultaneously of the eigenstates in the superposition even though >>> these eigenstates each have probabilities LESS than 100%. * >>> >>> >>> You're confounding "being in an eigenstate" with "having a component is >>> different eigenstates simultaneously". >>> >> >> *If you go to 5:15 in this >> video, https://www.youtube.com/watch?v=kTXTPe3wahc&t=7s >> <https://www.youtube.com/watch?v=kTXTPe3wahc&t=7s> , posted by Clark, the >> presenter explains the current interpretation of superposition, which I >> strongly object to. Maybe my argument was confused by my reference to >> eigenstates which spans some superposition. What I object to is the view >> that a system in a superposition is simultaneously in all states in its >> sum, which I called "components" (standard terminology?), which contradicts >> the CI that there are no preexisting states of a quantum system before >> measurement.* >> >> They can't be regarded a pre-existing states. In silver atom SG example >> the pre-existing state is know by preparation to be UP, so the LEFT and >> RIGHT states are not pre-existing (except as possibilities). >> > > *I dunno. I dunno if what you write above clarifies or confuses the issue. > And I admit I am unclear about spin state superpositions. But I do know > that a key assertion of QM is that a system before measurement has no > pre-existing property, or value, or state.* > > No, you don't know that. To know means to have a true belief based on > evidence. > *But I DO have evidence and so do you; Bell experiments! They show no pre-existing property, or value, or state exists before the measurement. Otherwise local realism would be confirmed, instead of failing. AG * > *Wasn't this Bohr's answer to the EPR paper or paradox? And what is a > superposition? Isn't it a solution of Schroedinger's equation for a > particular system which can be decomposed into sums of components, or > elements of a Hilbert space?* > > Hilbert space is a kind of vector space. Vectors can always be expressed > in terms of different basis vectors. > *I've refreshed my understanding of Hilbert spaces. So, if you really believe your second sentence above, doesn't it make the idea many worlds, whose existence depends on the selection of basis, ambiguous (to say the least)? AG * > *The video presenter claims superposition implies that the system is > simultaneously in all component states, and uses the double slit experiment > to "prove" his claim by noting the interference pattern. But isn't this > what we would expect if matter has wave properties according to DeBroglie? > That is, the electron, or whatever, goes through both slits since when > unobserved it behaves like a wave. In summary, the presenter's proof has no > merit IMO. It doesn't put the weird interpretation of superposition on firm > ground as he claims. AG* > > Feynman said any good physicists knows five different mathematics to > describe the same physics. > *I seriously appreciate Feynman. But the presenter's interpretation of interference in double slit experiment completely ignores DeBroglie, which seems a far superior explanation than claiming a PARTICLE moves through BOTH slits (and hence is in both slit states simultaneously). Ultimately, I suppose, it's a matter of taste, and IMO the presenter is throwing a very hard problem under the rug, in favor of a pseudo solution. AG * * |Clark and others adhere to the former view which I see as ridiculous, in part because the mathematics just says there's less than 100% probability of being in any of these states before measurement. Can a system really BE in a state with less than 100% probability? AG* > That appears to be a semantic question about the usage of the term "be in >> a state". The math says that the state vector can be described in terms >> to the components of any set of basis states, in which case it will in >> general have non-zero components from many or all of those basis >> states....just like a 3-vector in Cartesian coordinates can have x, y, z >> components and there are infinitely many ways of choosing x, y, and z. If >> you choose them just right the 3-vector may be (0,0,1) and be a z-state >> eigenvector. >> > > *Then the Many Worlds of the MWI are undefined. It depends on the basis > chosen, which could represent huge distinct sets of basis vectors. AG* > > One of the elements of the quantum measurement problem is why the "worlds" > are described in the same basis (usually position basis). Zurek proposes a > solution he calls einselection in which only some states are stable against > entanglement with the environment and so "worlds" can only exist in > (approximately) those states. > > 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]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/ba08dd96-0142-434f-85b1-9ea59a24da68n%40googlegroups.com.
