The Concept of the Universe in Physical Cosmology

The concept of the universe is used in physical cosmology differently from the usual meaning of the term, naively considered as the entire reality. Traditionally, thinking about the whole led to logical contradictions. Taking as reference the Kantian antecedent, different contemporary philosophical notions of the universe are analysed in the first part of this paper, including realist and constructivist approaches, as well as a notion of the universe as a physical object. In the second part, the specific notion from the standard physical cosmology is discussed. Although modelling the universe as a physical system provides a specific way to define some global properties, the universe as a whole remains empirically inaccessible. Hence, the discussion about the under-determined global properties depends ultimately on philosophical preferences. Under these circumstances, it is argued that the realist interpretation of such properties becomes problematic because it leads to unstable conclusions. Finally, it is argued that the notion of the universe as conceived in standard cosmology is not necessarily consistent with an approach that considers it to be a physical object.