Time's one-way direction goes all the way down: having a 'before' and an 'after' is part of what time *is*, not a label stuck onto an otherwise direction-neutral background. Nothing outside nature has to wind time up or aim it forward; being a medium at all is already enough.

Heat flows from hot to cold. Gas fills a vacuum. Broken eggs do not reassemble. The empirical asymmetry is not in dispute; the question is how deep it runs. The structural argument (the modal derivation of [§2.4](<2.4 Structural Requirement.md>) and the §7 root) answers: deep enough that *before* and *after* are not labels a symmetric manifold happens to wear. They are what Temporality is, at the constitutive level. The thermodynamic asymmetry, the cosmological expansion, and (on interpretations that treat measurement as a real collapse) the irreversibility associated with quantum measurement are convergent empirical reports of that constitutive tilt rather than deductive consequences of it; the bridge from constitutive temporal asymmetry to specific cosmological endpoints passes through the argument [§7.6](<7.6 Singularity.md>) takes up. That tilt is constitutive of Nature (the Temporality-Spatiality-Physicality unity established by Conditions-as-Nature and Triconditionality of Nature in §[§2.6.1](<2.6.1 Three Conditions, One Nature.md>)–2.6.12, with its necessity stated at [§2.8.5](<2.8.5 Necessity of Nature.md>), read as a single structural substrate), not anything added to it from without.


- [7.2.1 What is Disputed](<7.2.1 What is Disputed.md>)
- [7.2.2 What is Required](<7.2.2 What is Required.md>)
- [7.2.3 What is Predicted](<7.2.3 What is Predicted.md>)
- [7.2.4 What is Confirmed](<7.2.4 What is Confirmed.md>)
- [7.2.5 What is Concluded](<7.2.5 What is Concluded.md>)


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← [7.1 Convergence of Method](<7.1 Convergence of Method.md>) | [7.2.1 What is Disputed](<7.2.1 What is Disputed.md>) →
