----- Original Message ----- 
From: "Brent Meeker" <[EMAIL PROTECTED]>
To: "Saibal Mitra" <[EMAIL PROTECTED]>
Sent: Sunday, June 12, 2005 02:43 AM
Subject: RE: Observer-Moment Measure from Universe Measure


>
>
> >-----Original Message-----
> >From: Saibal Mitra [mailto:[EMAIL PROTECTED]
> >Sent: Sunday, June 11, 2000 4:01 PM
> >To: Brent Meeker; ":everything-list"@eskimo.com
> >Subject: Re: Observer-Moment Measure from Universe Measure
> >
> >
> >
> >----- Original Message -----
> >From: "Brent Meeker" <[EMAIL PROTECTED]>
> >To: "Saibal Mitra" <[EMAIL PROTECTED]>
> >Sent: Friday, June 10, 2005 06:41 PM
> >Subject: RE: Observer-Moment Measure from Universe Measure
> >
> >
> >>
> >>
> >> >-----Original Message-----
> >> >From: Saibal Mitra [mailto:[EMAIL PROTECTED]
> >> >Sent: Friday, June 10, 2005 11:39 PM
> >> >To: Brent Meeker; everything
> >> >Subject: Re: Observer-Moment Measure from Universe Measure
> >> >
> >> >
> >> >
> >> >----- Original Message -----
> >> >From: "Brent Meeker" <[EMAIL PROTECTED]>
> >> >To: "Saibal Mitra" <[EMAIL PROTECTED]>
> >> >Sent: Wednesday, June 08, 2005 02:23 PM
> >> >Subject: RE: Observer-Moment Measure from Universe Measure
> >> >
> >> >
> >> >>
> >> >>
> >> >> >-----Original Message-----
> >> >> >From: Saibal Mitra [mailto:[EMAIL PROTECTED]
> >> >> >Sent: Wednesday, June 08, 2005 1:16 PM
> >> >> >To: Patrick Leahy; Hal Finney; [EMAIL PROTECTED]; [EMAIL PROTECTED]
> >> >> >Cc: everything-list@eskimo.com
> >> >> >Subject: Re: Observer-Moment Measure from Universe Measure
> >> >> >
> >> >> >
> >> >> >I think one should define an observer moment as the instantaneous
> >> >> >description of the human brain. I.e. the minimum amount of
information
> >> >you
> >> >> >need to simulate the brain of a observer. This description changes
> >over
> >> >time
> >> >> >due to interactions with the environment. Even if there were no
> >> >interactions
> >> >> >with the environment the description would change, but this change
is
> >> >fixed
> >> >> >by the original description.
> >> >>
> >> >> That means that, supposing the brain is a classical, the "moment"
> >cannot
> >> >be
> >> >> defined by a description of values, omitting rates; just as the path
of
> >a
> >> >> ballistic projectile cannot be specified by it location, omitting
its
> >> >velocity.
> >> >> But to include rates means an implicit introduction of time and
> >continuity
> >> >of
> >> >> OMs.  This implies that OMs form causal chains and it makes no sense
to
> >> >talk
> >> >> about the same OM being in two different chains.
> >> >
> >> >
> >> >That's true in an isolated personal universe that is not interacting
with
> >an
> >> >'outside world'. I could, e.g. take your brain and simulate that on a
> >> >computer. The evolution equations for your brain are deterministic, so
> >the
> >> >simulation will describe a unique chain of causal links provided you
fix
> >the
> >> >boundary conditions.
> >> >
> >> >If the personal universe is embedded in another universe (like in our
> >case),
> >> >then the evolution equations will be constantly perturbed.
> >> >
> >> >
> >> >
> >> >
> >> >>
> >> >> But a lot of the motivation for OMs comes from the brain *not* being
> >> >classical;
> >> >> from the idea that the brain gets "copied" into Everett's multiple
> >> >relative
> >> >> states or MWIs.  Decoherence in the brain is very much faster than
the
> >> >> neurochemical processes - that's why it's approximately classical.
So
> >> >what is
> >> >> going on when QM predicts different OMs?  From Everett's point of
view
> >the
> >> >> brain must be treated as part of the QM system and it gets
"copied" -
> >but
> >> >not
> >> >> by itself.  Its description must include its entanglement with the
> >quantum
> >> >> systems observed.  So it seems that in either case, classical or
> >quantum,
> >> >an OM
> >> >> as a description of a brain state, has links outside itself.  In the
> >> >classical
> >> >> case it has casual links in time.  In the QM case it has Hilbert
space
> >> >links to
> >> >> what has been observed.
> >> >
> >> >
> >> >I agree. But the entangled state of a brain with the rest of the
universe
> >in
> >> >the MWI corresponds to an ensemble of different worlds such that in
each
> >> >member of the ensemble the brain is in some definite state.
> >> >
> >> >
> >> >>
> >> >> >So, I see no problem with Hal's way of thinking about OMs....
> >> >> >
> >> >> >
> >> >> >Observers are can be thought of as their own descriptions and thus
> >> >universes
> >> >> >in their own right. Observer moments are observers in particular
> >states
> >> >i.e.
> >> >> >their ''personal'' universe being in a certain state. The causal
> >relation
> >> >> >between successive states is already defined when we specify which
> >> >observer
> >> >> >we are talking about. i.e., we have already specified the laws of
> >physics
> >> >> >for the personal universe of an observer which defines the
observer.
> >> >> >Specifying the initial state of the personal universes thus
suffices.
> >> >>
> >> >> That would hold for a classical brain in a classical universe.  But
> >does
> >> >it in
> >> >> a QM universe?  I see a tension between the idea of "personal
universe"
> >> >and
> >> >> quantum entanglement.
> >> >
> >> >I don't see problems here. If you assume that our universe is
described
> >by
> >> >some fundamental laws of physics then those laws of physics also
describe
> >> >our brains. The way a particular brain works is thus fixed. This then
> >> >defines the personal universe.
> >>
> >> There seems to be a big jump between those last two sentences.
Defining
> >the
> >> laws of physics may define the *way* a brain works - but not its
content,
> >not
> >> the specifics of its processes - and the same for a universe.
> >>
> >> >Entanglement of the brain with another system
> >> >can only happen if there are interactions with the outside.
> >>
> >> Sure, and there must be such interactions according to what we know of
> >physics.
> >>
> >> >Even in the
> >> >classic case these intercations make the evolution of the personal
> >universe
> >> >nondeterministic.
> >>
> >> Right.  But in that case on "observer moment", defined as: "...one
should
> >> define an observer moment as the instantaneous description of the human
> >brain.
> >> I.e. the minimum amount of information you need to simulate the brain
of a
> >> observer." may have to include a lot of the universe outside the brain,
> >i.e.
> >> all the part that the brain is entangled with.   And in principle it's
> >> entangled with all those other MWs.
> >
> >
> >
> >I disagree here. Even a lot of what is going on inside the brain is not
> >relevant for consciousness. A well known example is that of people who
have
> >lost their sight due to brain damage. In some cases signals from their
eyes
> >still reach the brain but the part responsible for vision doesn't
function
> >anymore. In some cases these signals allow the person to avoid obstacles,
> >but the patient experiences such an avoidance movement as an involuntary
> >movement.
> >
> >
>
> Well that's an interesting point. You are dropping the definition of an OM
as
> the instantaneous description of a human brain and instead restricting it
to
> just enough of a description to...what?...capture
consciousness?...describe the
> content of consciousness?...to *be* conscious?
>




That's correct. Clearly an exact instanteneous description of the brain
contains too much information. So somehow you have to extract the OM form
that. Compare this to the computer that is simulating our solar system. The
computer running the simulation would be analogous to the brain, the
observer is analogous to the simulated virtual world which can be described
in terms of  ''planets'', a ''sun'' and Newtonian laws of physics. An OM can
be specified by specifying the state of the virtual solar system.


Saibal

Reply via email to