The nature of the universe and its relationship to other possible universes is still a topic of scientific inquiry and philosophical speculation. While there are various cosmological theories and hypotheses, there is currently no conclusive evidence to support the notion that our universe exists within another universe.
One concept that has been proposed in theoretical physics is the idea of a multiverse, which suggests the existence of multiple universes beyond our own. However, these universes are not necessarily nested within one another like a set of Russian dolls. Instead, they could exist independently or parallel to each other.
The concept of an infinite number of universes is also a subject of discussion in some interpretations of quantum mechanics and cosmology. These ideas stem from mathematical models and theoretical frameworks such as the Many-Worlds Interpretation and inflationary cosmology, respectively. However, it's important to note that these are still speculative ideas and not yet confirmed by empirical evidence.
Ultimately, the nature of the universe and the existence of other universes are intriguing areas of study, but our understanding of them is limited. Scientists continue to explore these concepts through theoretical and observational research, and future discoveries may provide further insights into the nature of our universe and its potential connections to others, if they exist.