Definition
The universe is the total set of physical reality. It encompasses all material objects, energy forms, the three-dimensional space where these entities exist, and the time dimension. It constitutes the general framework within which natural phenomena are organized.
Structure
The structure of the universe is based on a hierarchical distribution of matter and energy. One distinguishes successive levels, from elementary particles to galactic structures. Space is generally modeled as a four-dimensional continuum where gravity, electromagnetism, and the strong and weak nuclear forces operate. The observable universe is structured into clusters, filaments, and voids that form a coherent web.
Functioning
The fundamental mechanisms governing the universe are described by the laws of physics. These laws establish constant relationships between physical entities and allow for the predictability of phenomena. The fundamental interactions ensure the coherence of matter, the transmission of energy, the transformation of structures, and the dynamic evolution of space-time.
Evolution
The universe shows large-scale transformations. Physical states change over time, altering the density, temperature, and composition of matter and energy. Processes such as expansion, nucleosynthesis, structure formation, and cosmic radiation express this evolution. Each phase conditions the following ones through reproducible mechanisms.
Limits
The limits of the universe can be approached from various viewpoints: observational, measurable space, and theoretical. Some regions may be indirectly observable. Current physical models describe an expanding universe, but its totality could exceed what is currently detectable.