Dual arrows of time: SMM/DTT and Presentism and the growing-block universe

01The question behind the comparison

An arrow of time is an asymmetry with a specified meaning. A causal arrow concerns permitted influence; a thermodynamic arrow concerns typical entropy change; a psychological arrow concerns memory and anticipation. SMM/DTT adds a proposed generative orientation: production is organized toward completion, after which a result can participate in later records. These orientations can support one another, but their agreement is an explanatory question. A growing archive by itself says nothing about the entropy of the entire universe, and a time-symmetric microscopic law can still support asymmetric records when supplied with asymmetric conditions.

The phrase dual arrows is most useful when it names the relation between inner completion and outer succession. The inner orientation is functional: unfinished and finished configurations have different roles. The outer orientation is historical: a retained result can constrain later access. They need not be opposite vectors drawn on a plane. Drawing two arrows can obscure the real issue if no criterion identifies what reverses when an arrow is reversed. For example, reversing a movie reverses the displayed order, whereas unmaking its records would also require reversing changes in the storage device and environment.

The six nested levels locate completion inside a structured process. Nesting can explain why some operations depend on earlier achievements, but nesting alone does not establish irreversible dynamics. A perfectly reversible circuit also contains dependencies. A physical arrow can arise when a subsystem loses access to correlations, when a boundary state selects one orientation, or when a genuine noninvertible law is posited. These alternatives have different implications for energy, probability conservation and the possibility of recovering a previous state. DTT becomes sharper when it chooses between them in a particular model.

02The single-source and nested-time proposal

SMM begins with one nonspatial generative source. DTT distinguishes its inner production from the outer order in which completed results become accessible. The six inner levels are nested functional dependencies within that production; the seventh denotes outer completion. They are not six independent clocks, six spatial directions, or six simultaneously occupied temporal axes. This distinction makes the framework more specific than a general claim that everything changes: it asks how a world of persistent relations can be generated before its spatial representation is taken for granted. ^[2]

03The comparator’s explanatory structure

Presentism restricts concrete temporal existence to the present; the growing-block view includes the past and present while excluding the future. The distinction is decisive for a record-based ontology. A present record of yesterday and yesterday’s continuing existence are different claims. Broad’s treatment of becoming supplies the historical growing-block comparator; the presentist alternative sharpens what an archive does and does not establish.

Suppose a stone bears an inscription describing a vanished ceremony. A presentist can treat the inscription as a current object with a history. A growing-block theorist can additionally include the ceremony itself in reality. Both can agree about what the inscription says. The disagreement therefore cannot be settled by pointing to a stored record alone. SMM/DTT gains precision by stating whether renewal preserves past events, preserves only present traces, or uses another form of persistence. Relativity adds the separate question of how a privileged present, if proposed, relates to spatially separated events. ^[1]

04The precise agreement and difference

A growing block has an ontological orientation: the domain of existing events increases. Presentism has a privileged present but need not describe the past as an accumulating domain. DTT’s record arrow can fit both because a current state can contain increasingly rich traces even if past events do not remain actual. The growth of accessible information and the growth of existence are therefore different proposals.

This distinction matters for dual arrows. Inner completion may be directed toward creating a usable record, while outer history may be represented as a growing archive. Neither fact requires that the total physical entropy increase at every step. A reversible source with prepared memory can generate such an archive over a finite regime. If DTT instead identifies record creation with literal addition to reality, it adopts a stronger growing-block interpretation and must address how the boundary is defined across distant events. The comparison helps locate the real commitment: an arrow in the completion mechanism, an ontological growth law, or both, rather than a generic assertion that the future follows the past. ^[1]

05Worked example: what follows and what does not

Take a memory initially in a known state 0 and a fair bit X. A reversible copy maps (X,0) to (X,X). Before copying, the two devices are uncorrelated; afterwards they share one bit of mutual information. No information has been erased in this ideal operation. The record points toward the earlier value because of the initially blank memory and the chosen interaction. Restoring only the memory to 0 is a different operation, with a thermodynamic cost under the usual erasure assumptions. This simple distinction shows how a record arrow can depend on preparation without proving a fundamental violation of time-reversal symmetry. It also shows why a source-memory budget belongs inside any physical completion model.

06What this comparison contributes

The promising connection is a derivation of aligned orientations from a shared source law and admissible boundary conditions. An inner stage count would then acquire meaning through its relation to records and entropy production, not through the appearance of an arrow in a diagram. The conceptual gain is already useful: it prevents the familiar experience of passage, the ordering of causes and the irreversible loss of accessible information from being silently treated as the same phenomenon.

THE SAME QUESTION, DIFFERENT STARTING POINTS

The comparison at a glance

Continue on SMONAD

• Temporal asymmetry: reading the published model →

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• Publication record: Dual-Time Topological Geometry and the Emergence of Temporal Asymmetry in Non-Equilibrium Dynamics →

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• The Principle of Ever-renewed Creation →

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• Renewal and persistence: why a changing world can keep a history →

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• Time Chest →

  Connects this comparison with the author’s discussion of arrows.