Thanks for this great comment!

> He also uses Rice’s theorem (old) to show that there is no uniform measure over the set of "possible universes."

I assume a finite uniform measure? Presumably |set| is a uniform measure over the set of "possible universes".

Anyway if I understood that correctly, than this is not that surprising? There isn't a finite uniform measure over the real line. If you only consider the possible universes of two particles at any distance from eachother, this models the real line and therefore has no finite uniform measure.