Re: Is the universe computable

From: Kory Heath <kory.heath.domain.name.hidden>
Date: Mon, 26 Jan 2004 02:54:51 -0500

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".

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.

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.

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
Received on Mon Jan 26 2004 - 09:39:17 PST