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.

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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.
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.
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.
Hal Finney