On 18 Nov 2017, at 05:35, [email protected] wrote:
On Friday, November 17, 2017 at 7:18:23 PM UTC-7, Brent wrote:
On 11/17/2017 6:08 PM, [email protected] wrote:
On Friday, November 17, 2017 at 6:41:43 PM UTC-7, Brent wrote:
On 11/17/2017 4:04 PM, [email protected] wrote:
On Friday, November 17, 2017 at 2:38:40 PM UTC-7, Brent wrote:
On 11/17/2017 1:17 PM, [email protected] wrote:
I think "must" is unwarranted, certainly in the case of the MWI.
Rather, it ASSUMES all possible measurements must be realized in
some world. I see no reason for this assumption other than an
insistence to fully reify the wf in order to avoid "collapse".
Same situation in String Theory; no "must"; simply other possible
universes in the landscape. Do you really think that when you
pull a slot machine and get some outcome, the 10 million other
possible outcomes occur in 10 million other universe? Seems
ridiculous to me.
The problem is a conflict:
(1) If the wave-function collapses when does it do it and what is
the process.
The fact that we have unsolved problems, does not suggest we
should grasp as straws such as the MWI.
Does a human being have to look at the record? Is simply having a
recorde enough? But then what constitutes a record? Does it have
be made of more than 100 atoms, more than 10, more than 1? How is
the record created, if not by evolution of the Schrodinger equation?
If you consider a specific experiment, say the double slit using
micro objects like electrons, all you need is a recorder, any
recorder, and if it is designed to determine which-way, the
interference is destroyed. Thus, you don't need humans or
consciousness in any form to collapse the wf. Feynman discusses
this and it's quite conclusive IMO.
But you need to "collapse" it somehow by measuring the position of
the electrons - otherwise there is no interference pattern. So the
question remains, what is a measurement? If you replace the film
by an array of atoms and you plan to measure where the electron
lands by which atom it strikes and ejects from the array, you will
them have to make a second measurement to see which atoms are
missing. So "measurement" must include more interaction than that;
enough interaction to constitute a "record". But that seems to
just reword the problem. How much of a "record"? and what
constitutes a record?
I think these details can be worked out on a case-by-case basis.
But the main point seems solid; no human observers or consciousness
needed to produce interference, which is tantamount to collapse. Do
you agree to that? AG
I agree that a human observer is not necessary...even a Trump
supporter would suffice.
(2)If it's created by a splitting of the world, then you still
have the same questions with "splitting" in places of "collapse"
except that the SE does provide the evolution. But then in the
Schrodinger cat experiment the world is splitting continuously.
IMO, the problem posed by the cat is a macro object in an
unthinkable superposition of Alive and Dead simultaneously. But if
the object is macro, won't the interference
terms be vanishingly small, so small that the unthinkable
conclusion does not occur in the lifetime of the universe? IOW,
FAPP there is no superposition and thus no enigmatic superposition.
Forget the cat. It's the radioactive atom whose emission will
break the vial that causes the continuous splitting of the world:
decay at 0:00...0:01...0:02.... And is FAPP enough? There are
going to be intermediate cases in which there are 10 dof instead
1e30 dof, and the superposition can be eliminated by a change of
basis.
FAPP is probably not enough. What is the change of basis that
eliminates the superposition? For the singlet state, Bruce says
there is none and that I may have misunderstood your earlier
comments that every superposition can be eliminated by a change of
basis. TIA,
No, Bruce was thinking of what local operator could be implemented.
In theory any pure state can be an element of a basis. So if the
superposition is pure it will an eigenstate of some
operator....although in general it will often be one that is
impractical to implement.
Brent
If you can remove the superposition from any pure state by a change
of basis, why not do it for the cat and maybe the problem will go
away? AG
You can do that. Even after looking at the cat, and seeing it dead,
you can make a measurement on the global operator, and resurrect the
cat! of course, that is technically terribly demanding, and you will
have to erase all traces remaining of the dead cat state. That is just
technically unfeasible, and that is why, decoherence's result is FAPP
statistical and non reversible. It is as much difficult as to separate
the milk from the coffee, but it is possible in theory, and that is
what make the theory demanding the parallel universes, (or worst kind
of nonsensical weirdness like 3p indeterminacy and non-locality).
To me, it seems that the BI violation is a strong evidence for "many-
computations/histories", but not for non-locality.
Bruno
--
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.
http://iridia.ulb.ac.be/~marchal/
--
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.
