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. 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