Again travel has forced me to take an absence from this list for a while,
but I think I will be home for several weeks so hopefully I will be able
to catch up at last.

One question I would ask with regard to the role of time is, is there
something about time (and perhaps "causality") that goes over and above
the equations or natural laws that control and define a given universe?

Let us imagine a Cellular Automaton based universe; for simplicity, let it
be a 1-dimensional CA such as those studied in detail in Wolfram's book.
We have an x dimension and a t dimension, and some rules which are the
"natural laws" of that universe.  A sample rule might be
s[x,t+1] = s[x,t] XOR (s[x-1,t] OR s[x+1],t]).  This means that the
state at position x and time t+1 is the exclusive-or of the state at the
previous time (s[x,t]) and the OR of the left and right neighbor states.
In other words, a cell reverses its state if either of its neighbors is
"on".

Wolfram investigates all 256 possible rules which determine a cell's
next state from the previous state of the cell and its two neighbors.
Some lead to surprisingly complex patterns and it is conceivable that such
universes might even be complex enough to allow life and consciousness
to evolve.

So we have a notion of time, t, and space, x.  The question is this.
If we don't *call* it time, does that change things?  Suppose we have
a universe with 2 spatial dimensions, x and y.  But it is governed by
the same rule: s[x,y+1] = s[x,y] XOR (s[x-1,y] OR s[x+1],y]).  Here
I have replaced t in the rule above by y.

Does this make a difference?  I think we will agree that it does not.
Changing the letter t to the letter y does not change the fundamental
nature of this universe.  It only changes how we describe it.

Then we can ask, is this rather abstract description of the universe,
in terms of its natural laws, enough for us to know whether the
consciousnesses that exist in it are really conscious?  Or do we need
to know more?  Do we need to know details about how the universe was
created (whatever that means!)?  Do we need to know if there is a "flow"
of "causality" in this universe?

My answer is that the natural laws ought to be enough.  If we can find
a reasonable interpretation (defined rigorously as a mapping whose
information content is significantly smaller than the pattern itself) of
a pattern in the universe as something that we would consider a conscious
observer in our own universe, then we would be right to say that this
CA universe has consciousness.  (More precisely, that this CA universe
contributes measure to these instances and kinds of conscious observers.)

I don't think it makes sense to demand more information than the natural
laws (like, what kind of universal-computer is running to interpret
these laws, what algorithm it uses, how sequential is it, is it allowed
to backtrack and change things, etc.).  The laws themselves define
the universe.  The two are, in a sense, equivalent.  That is all the
information there is.  The laws should be, in fact they must be, enough
to answer the question about whether the consciousness which appears in
such a universe is "real".  That's how it appears to me.

In our own universe, we too have natural laws that relate to space and
time.  One such law is from Newton: d2x/dt2 = Force/Mass (i.e. F=ma).
Relativity and QM have their own laws that refer to x, y, z, and t.
Generally, t is treated differently than the other coordinates, which
are all treated the same.  But obviously we could substitute some other
letter, say q, for t and it would not make a difference.  A universe
with quime instead of time would be the same.

So again, is it enough to look at the natural laws of our universe in
order to decide whether the consciousnesses within it are real?  Or do we
need more?  Can we imagine a universe like ours, which follows exactly the
same natural laws, but where time doesn't really exist (in some sense),
where there is no actual causality?  I have trouble with this idea, but
I'd be interested to hear from those who think that such a distinction
exists.

Hal Finney

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