On 10 Mar 2014, at 02:15, meekerdb wrote:
On 3/9/2014 5:36 PM, LizR wrote:
Surely QM + collapse makes the prediction that there is a mechanism
that causes the collapse (e.g. Penrose's idea about it being
gravitational) and therefore predicts that at some point that
mechanism will kick in, so we can only have superpositions up to a
particular size?
Just as there must be some mechanism that causes us to perceive only
one reality, and not a superposition.
The mechanism is: look in your diary.
If you are in the superposed state "seeing the cat dead" + "seeing the
cat alive", there is no mysterious connection between the two brains,
and simple robotics explains why each brains is confronted with unique
but different alternate reality.
In Everett, it is the "simple" comp first person plural indeterminacy,
or even generalization of it.
There is no reason at all, with comp, that you will feel seeing M,
instead of W, but you know, by comp, that you will feel to be in only
one city.
The same occurs when you look to a cat in the state dead+alive, in the
base {dead, alive}.
Bruno
Brent
While QM on its own (i.e. Everett) predicts that there is no
collapse threshold - that if you can keep a system from decohering,
it will remain in a superposition regardless of how large it is.
So at some point QM+Collapse has to come up with a mechanism for
collapse, and at that point it becomes testable, at least in theory
(depending on our level of technology, I mean).
On 10 March 2014 13:17, chris peck <[email protected]> wrote:
Hi Bruno
>> With respect to the UDA, graves and me are just using
different vocabulary.
Really?
the last time I quoted her:
"What ... should Alice expect to see? Here I invoke the
following premise: whatever she knows she will see, she should
expect (with certainty!) to see. So, she should (with certainty)
expect to see spin-up, and she should (with certainty) expect to
see spin-down."
But that can only be a 3-1 description. She handles the 1p by a
maximization of the interests of the copies, and that is equivalent
with the FPI, without naming it.
Funnily enough Bruno, if I was opportunistic I would just about
accept that. I mean personally, I would argue that the vocabulary
used is identical between you and Greaves and she explicitly denies
your probability distribution from the first person perspective.
But a bigger problem for you raises its head if I put that to one
side.
if, as you claim, there is no substantive difference between your
theory and Greaves' just because she has some other mechanism of
deriving the bare quantities you want, then you may as well say
that there is only a difference in terminology between your theory
and any other interpretation of QM. After all they all deliver 0.5
by some now irrelevant metric too. You've just relugated your
theory to the purely metaphysical. You're tacitly admitting that
all these theories are just re-skins of the same underlying engine
with bugger all to choose between them.
In a way that is something that I have felt for a while. Everettian
QM does not improve upon QM + collapse in the way say relativity
improves on Newtonian physics. There is no concomitant improvement
in predictive capability on offer. Its a purely theoretical change
intended to smooth out conceptual difficulties but it can only do
that by delivering further difficulties of its own. All your
theories are scientifically irrelevant.
Date: Sun, 9 Mar 2014 11:32:08 -0700
From: [email protected]
To: [email protected]
Subject: Re: Tegmark and UDA step 3
On 3/9/2014 12:47 AM, Bruno Marchal wrote:
On 08 Mar 2014, at 06:16, meekerdb wrote:
On 3/7/2014 8:26 PM, LizR wrote:
On 8 March 2014 08:14, meekerdb <[email protected]> wrote:
On 3/7/2014 1:24 AM, LizR wrote:
On 7 March 2014 18:29, meekerdb <[email protected]> wrote:
On 3/6/2014 9:15 PM, Jason Resch wrote:
A related question is, is there any such thing as true randomness
at all? Or is every case of true randomness an instance of FPI?
Or is FPI just a convoluted way to pretend there isn't
true
randomness?
If one assumes QM and the MWI are correct then it isn't pretending,
True; but I don't assume that.
Since your original statement above only makes sense in some
context - which you haven't revealed, as far as I can tell -
perhaps you could tell us what you are assuming?
I'm not assuming anything, I'm just pointing out that one could
assume something different than QM and MWI. For instance, start
with MWI but then suppose that at each "branching" only one
instance of you continues. Doesn't that accord with all experience?
Like Ptolemeaus epicycles. The point is to accord with the simplest
theories we have for most if not all experiences, like QM, or
computationalism.
At each "branching" only one instance of you continue, you say, but
that does not accord well with the simplest explanation of the two
slits experience. You will have to explain why the superpositions
act in the micro and not the macro, and this needs big changes in
QM (= SWE), or even bigger to computationalism.
But you have to explain this anyway; except the question is
transformed into why do I only experience one reality. Presumably
the answer is in decoherence and the off-diagonal terms of the
density matrix becoming very small (or maybe even zero). Once you
have this answer then you can look at the density matrix, as Omnes
does, and say, "QM is a probabilistic theory, so it predicts
probabilities. What did you expect?"
My point is that these sharp questions are asked of QM because it
is a mature theory with lots of very accurate predictions, but
"comp" as a new speculative theory kind of gets a free ride on the
very same questions, e.g. why do we not experience superpositions?
Why isn't there a superposition of the M-guy and the W-guy
according to comp. How can consciousness be instantiated by
physical processes? Most people on this list just assume it can't
and dismiss the very idea as mere physicalism. But they don't ask
how can consciousness be instantiated by infinite threads of
computation - that's mysterious and consciousness is mysterious, so
it's OK.
If not, you can always consistently assume everything is done by a
God to fit your favorite philosophical expectations. You can do
that, *logically*, but this is no more truth research, but wishful
thinking.
But you know that is not what is done. QM predicts probability
distributions that are confirmed to many decimal places. QFT
predicts some measured values to 11 decimal places. And you rely
on QM to explain the world in in you theory of comp. Your approach
is to explain QM and then let QM do the rest of the work - which is
fine. But my point is that QM can still do the work even if it's a
probabilistic theory. So unless comp can make
some better predictions than comp it's just an interpretation and
it's trading off a distaste for randomness (a very restricted and
well defined randomness) for a love of everythingism. Which is why
I hope comp can predict something about consciousness; where it may
offer something beyond just interpretation.
Brent
Bruno
http://iridia.ulb.ac.be/~marchal/
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