What is the defining characteristic of the Level IV Multiverse, or the Mathematical Universe Hypothesis?
Answer
The proposal that any mathematically consistent structure corresponds to a real physical universe.
Level IV suggests that reality is defined by mathematical consistency; if a set of equations can describe a reality, that reality physically exists, potentially involving entirely new mathematical frameworks.

#Videos
How Many Universes Are There? - YouTube
How many universes are there? - Chris Anderson - YouTube
Related Questions
What is the fundamental nature of the concept referred to as the 'multiverse'?What assumption is central to the construction of the Level I Multiverse?Which physical theory is the primary source for the emergence of the Level II Multiverse?What causes the universe to split into parallel branches in the Level III Multiverse?What is the defining characteristic of the Level IV Multiverse, or the Mathematical Universe Hypothesis?How do Level II universes differ fundamentally from Level I universes?What specific numerical estimate arises from calculations related to the String Theory Landscape?What type of difference characterizes the variation between Level III quantum branches?What potential empirical evidence might link to the existence of Level II universes?Why does calculating a definitive number for the Level IV ensemble become meaningless?