us in a petri dish
i think the notion of us being in a petri dish being equivalent to us being in a different dimension is erroneous. specifically, if we are discussing dimensions, universes are related on a subset level, not on an equivalent level.
if we are in a petri dish ran by mice, then we are still within that universe and dimension. the dimensions which we find within this universe exist for us as well as for the mice. a concrete example on which to compare:
say we have 2 universes – one, in which a baby becomes a painter and one where the same baby becomes a businesswoman. say both of these universes have the baby actually being in a world that is inside a petri dish. they are still in the same dimension! one dimension, but 2 possible universes with in it.
hmm, on rereading i guess i’m agreeing with scarf’s 2nd last paragraph precisely.
a.i. and argument for matrix
hesi, i mentioned this to you. everyone else, here you go, someone far smarter than us argues The Simulation Argument: Why the Probability that You Are Living in a Matrix is Quite High.
i don’t want to go into discussing that possibility, except to say that in my opinion the discussion of artificial life or intelligence does not relate to the notion of multiple dimensions and universes. it is a seperate argument, for the sheer reason that it is possible logically for any combination of ideas on the above to exist without being contradictory. since we do not have clear evidence for one particular combination of “we are a petri dish” + “there are no alternative universes”, it is out of bounds to argue that from one, the other can follow.
in other words, there is no correlation between the two questions.
notion of folding
while i cannot possibly say that i am able to explain folding back to anyone coherently, it seems to make sense to me to draw parallels between 2-3 dimensions, to 3-4, etc. i.e. the folding of time and space must be allowed if we even want to argue that there is such a thing as a 2nd and a 3rd dimension.
more, more!

ha, didn’t expect this, did you :P