Eternalism

Eternalism is a philosophical theory of time that holds all points in time—past, present, and future—are equally real. In this view, the universe is a four-dimensional spacetime block in which events at different times exist with ontological equal status. Objects that persist through time are often said to have temporal parts, so becoming and change are features of our perspective within the block rather than fundamental aspects of reality.

Eternalism is contrasted with presentism, which holds that only the present moment and its contents are real, and with growing block theory, which holds that the past and present are real while the future is not. In eternalism, there is no absolute present slicing through spacetime; instead, all times exist in a unified ontological structure.

Relativity, particularly the relativity of simultaneity, is often cited in support of eternalism. Since different observers can disagree about what is simultaneous, there is no objective, observer-independent present. This leads some to view the block universe as a natural fit to modern physics, though the interpretation remains debated among physicists and philosophers.

Critics argue that eternalism undermines our ordinary sense of becoming and the openness of the future. Proponents respond that the intuition of becoming is compatible with a four-dimensional ontology once analyzed carefully, and that eternalism preserves causal relations and the explanatory power of physics without appealing to a privileged present.

A related terminology note: eternalism is commonly associated with perdurantism, the view that objects persist via temporal parts, though its core ideas are discussed independently of that label.