The Present-Only Universe

Based on the author's previously proven Self-Update Paradox in Closed Systems (Chen, 2026a https://doi.org/10.5281/zenodo.21921746), this paper extends the conclusion to a cosmological model of the universe as a finite-dimensional closed atomic storage system. First, three implicit axioms for the universe are supplemented: informational finiteness, non-injectivity of the evolution map (strengthened), and closure of update driving. It is then rigorously proven that deterministic evolution of the universe can only be destructive overwrite. This leads to the core theorem: physical reality is strictly equivalent to the state Uk under the current global discrete update index k—termed the "Meta-Instant" and denoted by η. The past state Uk−1 has been overwritten by the current state Uk and is irreversibly unrecoverable (even if the single-step evolution map is mathematically invertible, a finite state space under infinite continued updates necessarily suffers historical degeneracy collapse—because the number of possible histories grows exponentially with updates, while the state capacity remains fixed). The future state Uk+1 has not yet arrived; the current state awaits to be overwritten. The Meta-Instant is strictly defined as a discrete update counting primitive carrying no information entropy (H(η)=0), and it is proved that so-called "classical time readings" are not physical quantities but merely projection scalars of the current state under an observation function. Finally, this paper presents a dimensional reduction alternative to general relativity: continuous spacetime is a coarse-grained fitting representation of discrete couplings between neighboring lattice points.