The primary physical flaw in Tenet lies in its macroscopic misapplication of thermodynamics, specifically the Second Law (ΔS ≥ 0). The film posits that an object or human can have their entropy locally reversed (ΔS ≤ 0) while interacting with a forward-moving environment without causing catastrophic thermodynamic equilibrium. However, a biological organism operating with reversed entropy is biomechanically impossible; basic physiological functions like cellular respiration, neural action potentials, and digestion rely on strictly time-asymmetric chemical reactions. Furthermore, sensory perception would fail entirely; an inverted observer would theoretically emit photons from their retinas rather than absorb them, rendering them completely blind to the forward-moving world.
Causally, the film suffers from an irreconcilable tension between deterministic closed timelike curves and a mutable timeline. It heavily utilizes the Novikov Self-Consistency Principle, creating perfect bootstrap paradoxes where information, strategies, and physical objects exist without any original point of creation. While embracing this rigid block-universe logic—summarized by the mantra “what’s happened, happened”—the narrative simultaneously attempts to build suspense predicated on the idea that characters possess the free will to overwrite the past and prevent global annihilation, directly contradicting its own established deterministic framework.
Finally, the localized kinematics and energy transfers depicted in the film repeatedly violate standard mechanics and the conservation of momentum (∑p = 0). When inverted entities interact with forward-moving matter, the physics are applied selectively for cinematic convenience rather than consistency. For example, inverted fire is shown to cause freezing—a fundamental misinterpretation of heat transfer (q = mcΔT) across opposing temporal arrows—and inverted objects like bullets transfer momentum to forward-moving targets in ways that ignore the explosive, catastrophic energy release that would actually occur when two opposing physical realities intersect.
