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.
*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.
*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.
*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
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