The second law of thermodynamics states that the total entropy, the disorder, of an isolated system never decreases over time. It is among the most secure results in physics, holding without a single confirmed exception, and it is what gives time its felt direction: eggs break and do not unbreak, heat flows from hot to cold and not back, because the disordered arrangement is simply so much more probable than the ordered one. Extended to cosmological scale, the standard model predicts a long, one-way drift toward maximum entropy, sometimes called heat death, in which no further useful work or structured process remains possible.
Puranic cosmology names a different but related inevitability. Pralaya, dissolution, is built into the structure of time itself: a day of Brahma, a kalpa of 4.32 billion years, is followed by a night of equal length in which the manifest universe withdraws into an unmanifest state, and something is explicitly said to persist through that withdrawal rather than vanishing without remainder.
Here the honest comparison has to name a real disagreement rather than smooth it over. Standard cosmology’s heat death, on current understanding, does not cycle back; entropy’s increase is treated as effectively irreversible within an isolated system, full stop. Cyclic alternatives exist in physics, Roger Penrose’s conformal cyclic cosmology among them, but they remain minority proposals without consensus support, not the working model. Puranic time, by contrast, is explicitly and repeatedly cyclic, dissolution followed by fresh manifestation without exception, world without end in the most literal sense the texts intend.
What survives the disagreement is narrower and still worth having: both frameworks treat the current arrangement of structured matter as temporary by nature rather than by accident, something built into how time itself behaves rather than a misfortune that might have been avoided. Where they part ways, cleanly and instructively, is on whether temporary means it circles back or means it simply ends.
Part 4 of 20 — Series III: Through Two Lenses
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