On 9/05/2017 5:44 pm, Bruno Marchal wrote:
On 09 May 2017, at 01:07, Bruce Kellett wrote:
On 8/05/2017 8:48 pm, Bruno Marchal wrote:
On 08 May 2017, at 05:53, Bruce Kellett wrote:
I think the problem here is the use of the word "consistent". You
refer to "internally consistent computations" and "consistent and
hence intelligible 'personal histories'." But what is the measure
of such consistency? You cannot use the idea of 'consistent
according to some physical laws', because it is those laws that you
are supposedly deriving -- they cannot form part of the derivation.
I don't think any notion of logical consistency can fill the bill
here. It is logically consistent that my present conscious moment,
with its rich record of memories of a physical world, stretching
back to childhood, is all an illusion of the momentary point in a
computational history: the continuation of this computation back
into the past, and forward into the future, could be just white
noise! That is not logically inconsistent, or comutationally
inconsistent. It is inconsistent only with the physical laws of
conservation and persistence. But at this point, you do not have
such laws!
In fact, just as Boltzmann realized in the Boltzmann brain problem,
Can you give the reference please?
There are many book which give accounts of Boltmann's work, but an
accessible introductory overvies is given by Carroll himself in his
book "From Eternity to Here".
Thank you. But I am still looking for the precise place where
Boltzmann talk on its brain. Not only I don't find it, but nobody seem
able to provide that reference.
It seems that the name was not given by Boltzmann himself, but seems to
have originated from consideration of a short 1895 article by Boltzmann:
"On certain questions of the theory of gases". (Nature 51:413-15) in
which he considered the possibility that our Second Law might have
arisen from an extremely unlikely random fluctuation. I got this
reference from Penrose's recent book, "Fashion, Faith, and Fantasy in
the New Physics of the Universe".
states of complete randomness both before and after our current
conscious moment are overwhelmingly more likley than that our
present moment is immersed in a physics that involves exceptionless
conservation laws, so that the past and future can both be evolved
from our present state by the application of persistent and
pervasive physical laws.
Did Boltzman took into account QM? QM without collapse.
Why would he? Thermodynamics applies to both classical and quantum
physics and taking QM, with or without collapse, makes absolutely no
difference to the arguments here.
That seems weird.
Why?
Obviously he did not take into account mechanism and its measure
problem, and still believe in some brain mind identity link.
So what?
You answered it yourself yesterday. Carroll solution of the BB
problem, assuming it works in physics, cannot be lifted in the
computationalist framework, and still invoke the primary matter. It
might be the closest solution in physics, but it avoids the infinitely
many "BB" of all size in arithmetic. he does not take into account
that our mind, "here and now" is supported by infinitely many
computations.
Carrol was doing physics, not working in the computationalist paradigm.
I doubt that he would be very much concerned that his result cannot be
transferred there. The infinitely many BB of all size in arithmetic is
very much more your problem. I have commented on this in other posts.
Bruce
Unless you can give some meaning to the concept of "consistent"
that does not just beg the question, then I think Boltzmann's
problem will destroy your search for some 'measure' that makes our
experience of physical laws (any physical laws, not just those we
actually observe) overwhelmingly likely.
No problem, but you will need a non computationalist theory of mind
to assure the identity link. But most such theories are highly
speculative, and of the negative kind, as they need to add non
Turing emulable magic, nor non-FPI-recoverable magic, to just keep a
belief intact, when that belief is not sustained by any evidence,
just an habit since long.
That is just a lot of meaningless blather, with no relevance to the
questions at issue here. You still rely on the notion of "consistent
relative states", and all I am asking for is that you define what you
mean by "consistent", and what determines the presence or absence of
such consistency.
I explained it yesterday. Consistent is given by the dual of the boxes
for each hypostases. The logic of consistent extensions is different
for each points of view. For G, there are cul-de-sac "world"
everywhere, for Z, there are no cul-de-sac world at all, for example.
Have you grasp that p is consistent with PA means that PA + p does not
prove f? So ~p is not provable by PA. ~[]~p. So "consistent" is the
modal dual of provable, that is <>p. G is a normal modal logic, and so
we avoid the cul-de-sac in the material povs by attaching
conjunctively <>t to the box: []p & <>t, and that gives a new box,
having its own dual <>p v []f, which is the relative consistency
needed for the probabilistic measure.
Bruno
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