Four Densities of Temporal Construction: From String-Scale Slowness to Global Co-Presence

Time, in the informational sense developed in previous work, is the ordered construction of accessible distinctions under causal and energetic constraints. Metric time, as measured by clocks and described by spacetime geometry, is left unchanged. What varies is the density of temporal order that can be constructed at a given level of informational structure. This paper organises that variation into four regimes, ordered from the most microscopic to the most macroscopic: 1. String-scale regime: maximal density of interactions and distinctions; temporal construction is extremely dense and appears almost infinitely slow. 2. Intermediate scale regimes: level-dependent temporal density associated with physical scales (including electronic and biological structure), without requiring a conscious observer. 3. Observer-internal regime: temporal construction set by the sampling, memory, and stabilisation capacity of an interpreting system. 4. Global macroscopic limit: maximal accessibility to the whole content; sequential construction tends toward co-presence rather than a long ordered history. Event horizons are discussed as empirically established dense regimes in which metric time dilates for distant observers, and as candidates, within this framework, for informational decomposition toward string-like degrees of freedom. Cosmic voids illustrate the opposite pole of sparse distinction and minimal local temporal construction. The four densities are offered as a unifying map for earlier results on cosmic age, voids, flicker fusion, and the informational reading of observation.