Hal Finney writes
> Lee Corbin writes:
> > Hal Finney writes
> > > 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?
> > You yourself have already provided the key example in imagining
> > a two dimensional CA where the second dimension can be taken as
> > y instead of t.
> Okay, but perhaps I wasn't quite clear. I meant this to be a two
> dimensional CA that was completely self-contained, a universe of its own.
> It is not something that is embedded in our own universe or any larger
> structure. It is a self-contained mathematical/physical object with
> its own set of natural laws, just as we imagine our own universe to be.
It's pretty hard to imagine how "being embedded" would change
anything. The "laws" would still be there, no? (And by laws,
of course, we mean patterns whose description has lower KC.)
> My point was that whether we label the two dimensions x and t or x
> and y shouldn't make any difference in the properties of that universe.
> It still has the same fundamental structure. Changing the names only
> changes how we describe it, not what it is.
That seems clear.
> So I don't see this as an example of what I described above, a universe
> which matches another in its "laws of physics" but where one has causality
> and the other does not. That is, not unless someone would claim that
> it makes a difference whether the 2nd dimension is named y or t.
Perhaps you could address the biggest stumbling block that perhaps
I still have: continuity.
I'll even go out on a limb and suggest that *continuity* is really
what bothers a lot of people. A lot of us (e.g. Jesse Mazer) are
quite okay with, say, a program that uses the rules of Life to
give rise to a conscious entity. But we get really squeamish when
someone talks about just using the static, instant descriptions---
the generations of Life as depicted on, say, 2D grids. Even if you
have big a pile of such descriptions---trillions and trillions of
them---we point out that these snapshots are only frozen instants,
where the real "meat" was the continuous process (that so happened
to use the Rules).
P.S. I thought UD was "Universal Dovetailer", but now you mean
"Universal Description". We've got to get cautious using the
acronyms, or be sure, as you did here, to say what you mean in
P.P.S. Stephen Paul King was one of those who kept bringing up
the distinction between a *description* of something and the
thing itself. With what I have written above, I see a connection