The concept of whether the universe is an open or closed system can be approached from different perspectives.
From a thermodynamic standpoint, the universe is often considered a closed system. The fundamental principles of thermodynamics, such as the conservation of energy and the conservation of mass, apply to the universe as a whole. In this context, a closed system implies that energy and matter can neither be created nor destroyed within the system, but they can be exchanged or transformed among its components. According to our current understanding, the total energy and mass of the universe remain constant over time.
However, if we consider the universe in terms of its interaction with external influences or entities beyond its boundaries, the question of whether it is open or closed becomes more complex. From an observational standpoint, it is currently challenging to determine the precise nature of the universe at its cosmic boundaries, such as whether it is influenced by external factors or if it is part of a larger system.
Some cosmological models, like the concept of a multiverse, propose the existence of a broader framework that encompasses multiple universes or dimensions. In such models, the universe could be seen as part of a larger system, which would make it open in relation to that overarching structure.
Ultimately, the question of whether the universe is open or closed in the broader sense is still a subject of scientific investigation and debate. Our current knowledge and understanding of the universe's boundaries and interactions beyond them are limited, and further research and observations are needed to provide more conclusive insights into the nature of the universe as a system.