Q:

Is a type I parallel Universe possible?

A type I parallel Universe (according to Max Tegmark) is a universe that is infinite and looks everywhere more or less like our universe does (it's homogeneous). Tegmark claims that within this infinity there are regions say with a diameter of 100 000 lightyears that are indistinguishable from each other. Just by chance. Or take a Hubble volume, a volume as big as our visible universe, of which there are many (in fact infinitly many) exact copies of one another. So you and me are doing exactly the same thing in all those volumes.
Isn´t Tegmark forgetting that beyond the borders of all these exactly equal volumes, by definition, things are different? For example, no two balls of volume with a radius of 100 000 light years can be the same, because if I (and my presupposed copies) find myself (and my copies) somewhere near the border in one of those infinite amounts of exact copies and look with a telescope beyond the boundary of these copies all my copies see different things outside the ball, implying that all my copies are different and thus also the 100 000 light years sized balls. In other words doesn´t he overlook the interaction (via photons) between a volume and it´s surroundings?

A:

Well, you are supposed to think about a volume of 100000 light years radius around the solar system. If at a given instant, two volumes are exactly the same, even if there is a significant difference outside this volume, we will not be able to see this difference during 100000 years.
Even if you are at 1 meter from the ball border, to be able to see outside means you have to wait from light to reach your eye. The ball are identical now, that doesn't mean they will stay identical 3 nanoseconds later.

