On 5/26/2018 11:21 PM, 'scerir' via Everything List wrote:
Il 27 maggio 2018 alle 6.05 Brent Meeker <[email protected]> ha
scritto:
On 5/26/2018 1:37 PM, [email protected]
<mailto:[email protected]> wrote:
On Saturday, May 26, 2018 at 5:08:51 AM UTC, Brent wrote:
On 5/25/2018 9:50 PM, [email protected] wrote:
*Right. I was just making the observation that when we don't
see advanced EM waves (coming from the future?), it's generally
not seen as a big deal and they're ignored. But when
decoherence or the MWI implies the creation of full-blown
worlds (that we can't observe), there seems to be a large body
of opinion that accepts this bizarre result without serious
criticism that there's no mechanism or process for creating
full-blown worlds. No. I don't believe in such worlds. I tend
to think a large segment of professional physicists have gone
mad. AG*
Except you've got it backwards. There is a mechanism and
process for creating them FAPP, evolution by the Schroedinger
equation, which is the same process used in predicting results.
But there is no physical mechanism for making them
disappear....there's a mathematical process, i.e. taking the
partial trace which is the same as applying a projection
operator (with a little better justification).
There's a distinction between subspaces that are disjoint and
inaccessible to each other, and their non existence. Apparently you
want to make the case that their mutual inaccessibility is
equivalent to their non existence.
Operationally, it is.
Brent
Sometimes the principle of conservation of quantum information
(no-cloning, no-deleting) seems to have something to do with MWI -
conservation of quantum information and "relative state" formulation
both depend on linearity( ?) - in the sense that any other world must
be inaccessible (just to conserve quantum information).
I hadn't seen a paper spelling it out before, but it's pretty obvious.
Linearity, and even just determinism, imply conservation of
information. In classical mechanics when one of several possibilities
is realized, it's just attributed to information that was unknown to you
but which was present in the system. In QM you can never know all the
information in the system, so unpredictable things must occur. Then
conservation of information dictates that the other things must occur
too, but in some place you can't see.
Brent
s.
"In conclusion, we have shown that any theory for which dynamics is
linear with respect to stochastic mixing, the no-cloning and
no-deleting principles follow from the law of conservation of
information, and from whether two copies contain a different amount of
information than a single copy. In particular, this result allows us
to understand the physical reason for which perfect cloning or
deleting are impossible. They are forbidden because they infringe a
principle of conservation of information. Classically, two copies and
one copy contain the same information. However in the quantum case,
these information contents are generically different, putting
restrictions on cloning and deleting processes."
https://arxiv.org/abs/quant-ph/0407038
<https://arxiv.org/abs/quant-ph/0407038>
see also, for entropy issues, https://arxiv.org/abs/quant-ph/0306044
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