On 6/5/2018 5:05 PM, Bruce Kellett wrote:
From: <[email protected] <mailto:[email protected]>>
On Tuesday, June 5, 2018 at 7:02:11 PM UTC, Brent wrote:
On 6/5/2018 2:48 AM, [email protected] wrote:
*One objective was to convince myself whether the wf you have
written for decoherence makes any sense. Originally I thought
one needed mutual interference of all components for it to be
viable. I doubted whether each component interferes with the
others in your proposed wf because the |e> wave functions have
no well defined deBroglie wave lengths (which I thought were
necessary for a valid quantum superposition).*
de Broglie wave lengths are useful when thinking about a
particle, but a complex system with many degrees of freedom has
many different energy levels available to it and each one evolves
with a different frequency. So the de Broglie wavelength is not
very useful.
Brent
*Agree. That's what Bruce wrote, in effect, when he noted that the
macro states in the superposition for decoherence are just symbols
for the multitude of entanglements, each presumably with its own
deBroglie wave length**. But now I don't see the problem -- the weird
implications --with these superpositions involving macro systems as
dependent on interference. If the S Cat's wf can be written as a sum
of two states, each entangled with the radioactive source, the
implication is that the Cat is simultaneously alive and dead. It's
like a simple vector in the plane -- those pointy things -- which can
be written as the sum of a horizontal and vertical vectors (or a non
orthogonal basis). If it can be written as a sum, it can be
interpreted as manifesting both vectors in the sum simultaneously.
So, if you want to write state vectors to include entanglements with
macro systems, you will get cats that are alive and dead
simultaneously, and in the decoherence case, you'll ger copies of
this universe, inclusive of copies of observers, etc. That was
Schrodinger's point; the fallacy of entangling quantum and macro
states in one wf. AG*
Yes, Schrödinger's original intention with the cat scenario was to
provide a /reductio ad absurdum/: the conclusion of cats being
simultaneously alive and dead was patently absurd. In later life
Schrödinger regretted introducing his wave equation. His idea had been
to formulate quantum phenomena in terms of something easily
visulizable in a classical way, such as wave motion. This was as an
antidote to what many saw as the increasing obscurantism of Bohr and
the Copenhagen school. However, he was disappointed by the results,
and by the fact that his wave equation became the standard way of
thinking about quantum processes. Schrödinger was undoubtedly aware
that there were other ways of doing quantum calculations than in terms
of his wave equation; Heisenberg matrix mechanics was already
available, then there is Schwinger's mathematical approach, path
integral approaches, and so on. None of which need mention a wave or a
wave equation. They all give the same results for quantum
probabilities so since they were equivalent in this sense, they were,
according to the metaphysics of the time, all considered to be the
same theory.
But it is doubtful if they are all actually the same theory, since
they seem to imply different ontologies. Schrödinger's wave mechanics
has led to the reification of the wave function itself, and the result
is many worlds theory. But if you don't have a wave equation and work
only with matrices, there is no reason to postulate any multiplicity
of worlds. The model that you use for calculations in the theory
implies an ontology, and not all implied ontologies are the same, or
even equally useful. People are all to ready to believe that the
simplest ontology of their model is what is "really real". But they
are generally mistaken, as the negative induction of scientific
realism points out.
Bruce
Well said. Bohmian QM also gave the same answers as CI, but has a
different ontology and is deterministic. It's randomness comes from
ignorance of the initial state. CI postulates intrinsic randomness.
MWI is deterministic but postulates ignorance of where you'll end up.
QBism assumes personal randomness.
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 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.
