On 5/13/2015 8:49 AM, David Nyman wrote:
On 13 May 2015 at 14:53, Bruno Marchal <[email protected]
<mailto:[email protected]>> wrote:
I think it is a good summary, yes. Thanks!
Building on that then, would you say that bodies and brains (including of course our
own) fall within the class of embedded features of the machine's generalised 'physical
environment'? Their particular role being the relation between the 'knower' in platonia
and the environment in general. At a 'low' level, the comp assumption is that the FPI
results in a 'measure battle' yielding a range of observable transformations (or
continuations) consistent with the Born probabilities (else comp is false). A physics
consistent with QM, in other words. But the expectation is also that the knower itself
maintains its capacity for physical manifestation in relation to the transformed
environment, in each continuation, in order for the observations to occur.
BTW, Bruce made the point that the expected measure of the class of such
physically-consistent observations, against the background of UD*, must be very close to
zero. ISTM that this isn't really the point (e.g. the expected measure of readable books
in the Library of Babel must also be close to zero). What seems more relevant is the
presumed lack of 'un-physical' observer -environment relations (i.e. not only 'why no
white rabbits?' but 'why physics?'). From this perspective, the obvious difference
between the Library of Babel and UD* is that the former must be 'observed' externally
whereas the latter is conceived as yielding a view 'from within'. Hence what must be
justified is why our particular species of internal observer - i.e. the kind capable of
self-manifesting within consistently 'physical' environments, should predominate.
As they say on TV, "This just in!"
/Why Boltzmann Brains Don't Fluctuate Into Existence From the De Sitter Vacuum//
//Kimberly K. Boddy, Sean M. Carroll, Jason Pollack//
//(Submitted on 11 May 2015)//
//
// Many modern cosmological scenarios feature large volumes of spacetime in a de Sitter
vacuum phase. Such models are said to be faced with a "Boltzmann Brain problem" - the
overwhelming majority of observers with fixed local conditions are random fluctuations in
the de Sitter vacuum, rather than arising via thermodynamically sensible evolution from a
low-entropy past. We argue that this worry can be straightforwardly avoided in the
Many-Worlds (Everett) approach to quantum mechanics, as long as the underlying Hilbert
space is infinite-dimensional. In that case, de Sitter settles into a truly stationary
quantum vacuum state. While there would be a nonzero probability for observing
Boltzmann-Brain-like fluctuations in such a state, "observation" refers to a specific kind
of dynamical process that does not occur in the vacuum (which is, after all,
time-independent). Observers are necessarily out-of-equilibrium physical systems, which
are absent in the vacuum. Hence, the fact that projection operators corresponding to
states with observers in them do not annihilate the vacuum does not imply that such
observers actually come into existence. The Boltzmann Brain problem is therefore much less
generic than has been supposed. /
arXiv:1505.02780v1 [hep-th]
Brent
David
--
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]
<mailto:[email protected]>.
To post to this group, send email to [email protected]
<mailto:[email protected]>.
Visit this group at http://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.
--
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 http://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.
