On 09 May 2017, at 10:20, Bruce Kellett wrote:
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".
Thank you very much, Bruce.
If anyone has an exemplar of Boltzmann's "On certain questions of the
theory of gases", (Nature 51:413-15), I am interested.
Best,
Bruno
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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