I commend you for taking the time to look over the links!
CodeBlackv2 wrote:I found the fly in the ointment with this. The existence of other universes is irrelevant. The reason is that the other universes have no effect on our universe, and have never had any effect. The initial conditions in this universe are not determined or even related to the initial conditions of another universe, since the theory claims they are random. They cannot effect us and we cannot effect them, so their existence is irrelevant.
I understand what you are getting at and you have a valid point but, to me, this is like saying it's irrelevant that the sun doesn't rotate around the earth. I mean, regardless of which celestial object is rotating around which, there will still be four seasons in a year, day and night, etc. Sometimes the truth is irrelevant but as DIsson8er was sort of suggesting in his post, the pursuit of truth should be paramount.
You also seem to have some good questions regarding the level I multiverses but I specialize more in the level IV line of thought and am not a physicist.
I'm not saying that I know for a fact that there is no multiverse but we must have a sound basis for theorizing such a thing. At the very least this is a not fully formed theory. And if there is a multiverse, so what? How does it relate to I.D.?
If Max is right about the level IV multiverse, then reality itself is isomorphic to some asofyet undiscovered mathematical structure. Then the question becomes what are the origins of this mathematical structure. Many mathematical philosophers debate whether or not structures pre-exist or are created by mathematicians. I personally feel that mathematical objects are discovered and not created. Not created means not designed. That's the punchline.
There is the issue of whether or not reality literally is that mathematical structure or if isomorphism is the best we can say. Tegmark uses a possibly circular argument in deriving the mathematical universe hypothesis from the external reality hypothesis. But this can of worms is probably the purview of a different thread maybe...