Multiverset

Multiverset is a term used to describe a hypothetical collection or set of universes, collectively forming a higher-order ensemble. Unlike the common usage of “multiverse” to denote multiple universes, “multiverset” emphasizes the set-theoretic or catalogued nature of the totality, and it is not standard in mainstream physics. It appears mainly in philosophical discussions, speculative thought experiments, or certain works of fiction as a way to treat multiple universes as a single entity.

In physics and cosmology, several theories imply the existence of a multiverse, including eternal inflation, the string theory landscape, and certain interpretations of quantum mechanics. A multiverset can be used to conceptualize these ideas as a mathematical or ontological collection rather than as a network of interrelated branches. However, there is no empirical method to verify a multiverset, and many physicists would describe these ideas as speculative or untestable at present.

Properties ascribed to a multiverset are highly model-dependent; proposed universes may vary in physical constants, laws, dimensions, or initial conditions. Connections between universes—if any—are speculative and range from causal separation to hypothetical tunneling or branching processes.

In philosophy, the concept serves as a tool for discussions about modality, necessity, and possibility. In science fiction, it functions as a narrative device enabling exploration of alternate histories, parallel lives, or divergent physics.

Critics note that lack of empirical access and the problem of assigning measures or probabilities to an ensemble undermine testability and limit explanatory power. The term “multiverset” is therefore rarely used in formal literature, with “multiverse” remaining the common umbrella term. Related concepts include the multiverse, many-worlds interpretation, eternal inflation, string theory landscape, and modal realism.