On 8/05/2017 2:45 pm, spudboy100 via Everything List wrote:
Rather than use the Boltzmann Brain hypothesis to elucidate the
conservation of energy in thermodynamics and entropy, why not take
Boltzmann a bit more seriously, and search for these suckers in the
galaxy, in other words, treat, as a working hypothesis BB's as real
phenomena? There's nobody out there that is sending easy to listen to,
signals. Maybe the BB's are probing people's butts as a prank, by
pretending they are UFO's? Hardee Har Har!
I think that, given a physical universe, Boltzmann brains are highly
unlikely. The reasons are essentially those elucidated by Sean Carroll,
http://arxiv.org/abs/1405.0298v1 . Namely de Sitter space is a quiescent
vacuum in which there are no quantum fluctuations of the sort
hypothesized to give rise to Boltzmann brains. The problem is that David
(and Bruno) cannot appeal to such an argument, because Carroll
presupposes a physical universe, and they can't do that on pain of
circularity.
Bruce
In fact, just as Boltzmann realized in the Boltzmann brain
problem, 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.
-----Original Message-----
From: Bruce Kellett <[email protected]>
To: everything-list <[email protected]>
Sent: Sun, May 7, 2017 11:53 pm
Subject: Re: What are atheists for?
On 8/05/2017 3:14 am, David Nyman wrote:
On 6 May 2017 11:04 p.m., "Brent Meeker" <[email protected]
<mailto:[email protected]>> wrote:
On 5/6/2017 2:45 PM, David Nyman wrote:
On 6 May 2017 10:16 p.m., "Brent Meeker"
<[email protected] <mailto:[email protected]>> wrote:
But that's what I mean when I say Bruno's theory has
no predictive success. QM (and Everett) would
correctly predict that alcohol molecules in the blood
will interfere with neuronal function and THEN
invoking the physicalist theory of mind, i.e. that
mind supervenes on material events, it predicts that
your ability to do arithmetic will be impaired by
drinking tequila. It will NOT predict the contrary
with more than infinitesimal probability. So it's
misdirection to say that it's just a measure problem.
Without having the right measure a probabilistic
theory is just fantasy...or magic as Bruno would say.
I have no idea why you say that. I thought it was clear
that if computationalism doesn't (ultimately) predict that
its predominating computational mechanism (i.e. the one
effectively self-selected by complex subjects, in this
case, like ourselves) is the physics those selfsame
subjects observe,
That would certainly be an accomplishment - which in another
post Bruno says is trivially accomplished even in RA (I don't
see it). But to succeed in prediction it is not enough to
show that some world exists in which mind and physics are
consistent (that the physics that mind infers is also the real
physics that predicts effects on the mind). You need also to
show this has large measure relative to contrary worlds. One
can make a logic chopping argument that it must be that way
for otherwise minds would not be making sense of the physics
they perceived - but that makes the whole computational
argument otiose.
I've been thinking a bit more about this and I'd like to set out
some further tentative remarks about the above. Your professional
expertise in these matters is orders of magnitude greater than
mine and consequently any comments you might make would be very
helpful. By the way, it would also be helpful if you would read
beyond the next paragraph before commenting because I hope I will
come by myself to the fly in the ointment.
Firstly, and "assuming computationalism" on the basis of CT + YD,
we are led to the view that UD* must include all possible
"physical" computational continuations (actually infinitely
reiterated). This of course is also to assume that all such
continuations are finitely computable (i.e. halting). Now, again
on the same assumptions, it might seem reasonable that our
observing such a physics in concrete substantial form is evidence
of its emergence (i.e. epistemologically) as the predominant
computational mechanism underlying those very perceptions. Hence
it might seem equally reasonable to conclude that this is the
reason that these latter correspondingly appear to supervene on
concrete physical manifestations in their effective environment.
Now wait a minute. We cannot escape the question of measure. Why
would it be reasonable to assume that a physics of this sort
should predominate in the manner outlined above? Well, firstly, it
would seem that the generator of the set of possible physical
computations is infinitely reiterative​ and hence very robust
(both in the sense of computational inclusiveness a la step 7, and
that of internal self-consistency). But who is to say that the
generators of "magical" or simply inconsistent continuations
aren't equally or even more prevalent? After all we're dealing
with a Library of Babel here and the Vast majority of any such
library is bound to be gibberish. Well, I'm wondering​ about an
analogy with Feynman's path integral idea (comments particularly
appreciated here). Might a kind of least action principle be
applicable here, such that internally consistent computations
self-reinforce, whereas inconsistent ones in effect self-cancel?
Also, absence of evidence isn't evidence of absence. I'm thinking
here about the evaluation of what we typically remember having
experienced. I can't help invoking Hoyle here again (sorry).
Subjectively speaking, there's a kind of struggle always in
process between remembering and forgetting. So on the basis
suggested above, and from the abstract point of view of Hoyle's
singular agent (or equally Bruno's virgin machine), inconsistent
paths might plausibly tend to result, in effect, in a net
(unintelligible) forgetting and contrariwise, self-consistent
paths might equally plausibly result in a net (intelligible)
remembering. I'm speaking of consistent and hence intelligible
"personal histories" here. But perhaps you would substitute
"implausibly" above. Anyway, your comments as ever particularly
appreciated.
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,
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.
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.
Bruce
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