A new philosophical-physical analysis has called into question one of the most popular interpretations of relativity theory — the concept of the "block universe," according to which the past, present, and future exist simultaneously as parts of an unchanging four-dimensional block of space-time.

The work was published in the journal New Scientist.

What the "block universe" is

The idea, known as eternalism, follows from Einstein's special theory of relativity. Since different observers do not share a single "now," many physicists conclude that all moments in time are equally real. The past does not disappear, the future already "exists" — we are simply moving through this static four-dimensional structure, and the feeling of the passage of time is considered a subjective illusion of consciousness.

A new view of time

The authors of the analysis believe that such an interpretation confuses a mathematical model with physical reality. From the time-symmetry of equations, it does not follow that the past and future physically exist on an equal footing with the present. They lean toward an alternative position — presentism — according to which only the present is real, and the passage of time is an objective property of nature, not a construct of perception.

This point of view is shared by some specialists in the field of quantum gravity.

Arguments against the "block"

One of the key arguments was the thermodynamic arrow of time: the entropy of the Universe invariably increases in one direction, creating a clear physical asymmetry between past and future. If the past and future were equally real, explaining this asymmetry would be extremely difficult.

Additional support for presentism comes from developments in quantum gravity. In particular, in loop quantum gravity, space-time is not a fundamental entity but emerges as an approximation on large scales. In this case, the continuous flow of time may turn out to be the primary structure of reality.

Significance of the debate

The authors emphasize that their analysis does not disprove relativity theory as such — it still perfectly describes physical phenomena. The question is deeper: to what extent is it legitimate to identify a mathematical model with the ontological structure of the universe?

In their opinion, physics needs more careful language when discussing the nature of time.

In brief

Physicists have called into question the concept of the "block universe," in which the past, present, and future exist simultaneously. According to the new analysis, the feeling of the passage of time may reflect objective reality rather than being an illusion of consciousness. The thermodynamic arrow of time and ideas from quantum gravity support presentism — the view that only the present is real. The work does not invalidate relativity theory but offers a more careful interpretation of its philosophical implications.