Dear Kory,
Interleaving below.
----- Original Message -----
From: "Kory Heath" <kory.heath.domain.name.hidden>
To: <everything-list.domain.name.hidden>
Sent: Monday, January 26, 2004 2:54 AM
Subject: Re: Is the universe computable
> At 1/24/04, Stephen Paul King wrote:
> > I should respond to Kory's ME == PE idea. In PE we find such things
as
> >"thermodynamic entropy" and "temporality". If we are to take Kory's idea
> >(that Mathspace doesn't require resources) seriously, ME does not. This
> >seems a direct contradiction!
> > Perhaps Kory has a paper on-line that lays out his thesis of
> >"Instantiationism".
>
> No, I wish had the energy to write such an online paper. :) Anyway, please
> note that my own position is not "Instantiationism". This was the word I
> used to describe the position that I *don't* accept - i.e., the idea that
> computations need to somehow be physically instantiated in order for them
> (or more importantly, the SASs within them) to be "real" or "conscious".
If
> I had to come up with a name for my position, I might call it
"Mathematical
> Physicalism".
[SPK]
I am not arguing for the necessity of physical instatiation, in the
sense of a "prior". I am claiming that the notion of computation itself,
however one wants to represent it, implicitly requires some form of
implementation, even if such is merely "possible" if one is going to try to
build a theoretical model of the world we experience, a world where we can
not predict to arbitrary accurasy "what is going to happen next".
The idea I have is that the computations that render our worlds of
experience are implemented by the unitary evolution of quantum mechanical
systems and that these computations are not reducible to Turing Machines.
Notice that this idea involves a form of realism for quantum
wavefunctions similar to that proposed by Bohm and others.
> I have to confess that I'm not sure I'm following your argument. Are you
> referring to the tension between the static view of Mathspace, in which
> there is no concept of "resources" and computational structures exist "all
> at once", and the dynamic, 1st-person view that we have as creatures,
where
> time exists and resources are limited? I'm willing to admit that there's
> tension there, but it seems to me that the tension exists for the
> Instantiationist as well as the Mathematical Physicalist.
>
[SPK]
Yes, that "tension" is part of what I am trying to address. There is a
similar situation involved in the "problem of Time". One solution has been
proposed by Julian Barbour with his idea of a "time capsule". I hope that
you get a chance to read his book "The End of Time" which discusses this
idea.
I have serious problems with Barbour's proposal and have found that it
is the same problem that I trying to point out as existing in the various
computalionalist theories. His "best matching" scheme involves the same kind
of computational intractibility that disallows it to be taken as
"preexisting".
> All I can do is trundle out the same old thought experiments that we're
all
> familiar with. Imagine a 2D CA in which the state of each cell is
> determined by the state of its neighbors one tick in the "future" as well
> as one tick in the "past". Such CA cannot be computed "one tick of the
> clock at a time" like a regular CA. Instead you'd have to consider the
> whole structure as a 3D block of bits (one of the dimensions representing
> time) and somehow "accrete" the patterns within it. Or you could do a
> brute-force search through every possible block of bits, discarding all
> those that don't follow the rules. Some of the universes that you're left
> with may exhibit "thermodynamic entropy" and "temporality" - we can
imagine
> a particular block universe that contains patterns which represent
> observers moving around, interacting with their environment, etc. - and
yet
> from our perspective the whole structure is entirely static.
[SPK]
Your 3D CA will only work IF and only IF the computational content is
Turing Machine emulable and this requires that the TM is specifiable with
integers (enumerable). This, to me, explains why Comp proponents only seen
to want the Intergers to exist and will go to great and clever lengths to
"explain" why only they are needed.
The problem is that there is a large class of physical systems that are
not "computable" by TMs, i.e., they are "intractable". Did you read the
Wolfram quote that I included in one of my posts? Please read the entire
article found here:
http://www.stephenwolfram.com/publications/articles/physics/85-undecidability/2/text.html
Another way of thinking of this is to concider the Laplacean notion
where given the specification of the "initial conditions" and/or "final
conditions" of the universe that all of the kinematics and dynamics of the
universe would be laid out. The modern incarnation of this is the so-called
4D cube model of the universe. Again, these ideas only work for those who
are willing to completely ignore the facts of computational complexity and
the Heisenberg Uncertainty principle.
> There certainly seems to be a kind of mystery when we think about
> "temporality" within this static structure. We can "follow along with our
> finger" and "watch" some creature - some pattern of bits in the block
> universe - struggling valiantly against some obstacle in its environment.
> Yet clearly our act of following along with our finger is not suddenly
> making that creature conscious. The computations have already been
> performed - the entire block universe has already been physically
> instantiated. All we're doing now is observing it, like looking at the
> frames of a film. So at what point in time was that creature actually
> conscious? Did it happen "all at once" when our computation "found" that
> block universe? These are deep and murky questions, and I don't see how
the
> idea of "physical instantiation" makes them go away. Indeed, it's
precisely
> these "block universe" scenarios that suggest that it *does* make sense to
> view our universe as existing "all at once" out there in Mathspace, even
> though I'm in here perceiving it in this temporal fashion.
>
> -- Kory
[SPK]
The crux of my claim is that it is not possible that "the computations
have already been performed". The complexity of the required computations
are such that at best we may take the computations to be "ongoing". Time,
when, can be considered as the 1st person aspect of this computation...
For a good disscussion of this please read:
http://www.cs.brown.edu/people/pw/papers/ficacm.ps
http://www.cs.brown.edu/people/pw/papers/cm.ps
http://www.cse.uconn.edu/~dqg/inter_book.html
http://www.cs.brown.edu/people/pw/home.html
Kindest regards,
Stephen
>
Received on Mon Jan 26 2004 - 13:44:18 PST