The idea you're proposing is an interesting concept, but it is not currently supported by scientific evidence or widely accepted within the scientific community.
In quantum mechanics, superposition refers to the ability of a quantum particle to exist in multiple states simultaneously until it is observed or measured, at which point it "collapses" into one specific state. However, it is important to note that superposition is typically observed at the quantum level, involving microscopic particles like electrons or photons, rather than at the macroscopic level of the entire universe.
The universe is an incredibly complex and vast system comprising countless particles, fields, and interactions. While quantum mechanics provides a successful framework for understanding the behavior of particles on a small scale, it is not yet fully understood how these principles apply to the universe as a whole.
Currently, the prevailing cosmological model, known as the Big Bang theory, describes the expansion and evolution of the universe from a hot, dense state. This model is based on observations, such as the cosmic microwave background radiation and the large-scale structure of the universe, which are consistent with the idea that the universe originated from a highly compressed state and has been expanding ever since.
It is worth mentioning that scientists continue to explore and investigate the nature of the universe, including the possible connections between quantum mechanics and cosmology. However, the specific idea you mentioned, where the entire universe is in a superposition as every particle, is not a mainstream scientific perspective at this time.