Christopher Nolan’s Tenet (2020) is built around a concept called time inversion, which is loosely inspired by entropy in physics. While it takes significant creative liberties, the film’s core idea is based on real scientific principles from thermodynamics, quantum mechanics, and relativity.
1. Entropy: The Core Scientific Concept
At the heart of Tenet is entropy, a fundamental concept in thermodynamics.
Entropy measures the level of disorder in a system.
A natural system (e.g., a glass shattering) moves from order —> disorder over time.
The Second Law of Thermodynamics states that entropy always increases in a closed system - this is why time flows forward.
Time and entropy are deeply connected.
In traditional physics, time’s arrow is defined by increasing entropy.
Nolan’s idea of “time inversion” imagines a world where entropy can be reversed, meaning an object or person experiences time in the opposite direction from the rest of the world.
2. Time Inversion vs. Time Travel
Unlike traditional time travel, where someone moves between fixed points in time (e.g., Back to the Future), Tenet’s time inversion means:
Objects or people don’t jump through time but instead reverse their own timeline while the rest of the world moves forward.
If a person is inverted, they breathe CO instead of oxygen, because their biological processes are running in reverse.
Causality still exists, but it operates in a paradoxical loop: effects seem to precede their causes.
3. How Inversion Works in the Film
In Tenet, special “Turnstiles” allow people and objects to be inverted.
Once inverted, everything feels reversed:
Explosions shrink back into bombs.
Bullets return to the gun instead of being fired.
A car crash plays out in reverse (as seen in the highway chase).
Dual-time flow: Normal and inverted characters exist simultaneously, interacting in paradoxical ways (e.g., the protagonist fights his past self unknowingly).
4. Quantum Mechanics: Is It Possible?
While real-world quantum mechanics suggests some reversibility at microscopic scales (like in wavefunction collapse or CPT symmetry), reversing entropy in macroscopic objects (like humans) is pure science fiction.
However, certain interpretations of physics (e.g., block universe theory) suggest that past, present, and future exist simultaneously, which aligns with how Tenet treats time.
5. Temporal Pincer Movements: A Narrative & Strategic Device
One of the most original elements of Tenet is the temporal pincer movement:
This is a military strategy where one team moves forward in time and another moves backward.
The forward team learns from the inverted team’s future knowledge, creating an informational loop.
This reflects determinism, where the future already exists and the characters are merely fulfilling it.
6. Grandfather Paradox & Fate
Tenet engages with the Grandfather Paradox - if you go back in time and kill your grandfather, how do you exist to do it?
Instead of resolving this paradox, the film suggests a predetermined timeline - events must happen as they always have.
Final Thoughts: Nolan’s Vision of Time
Tenet is not a realistic take on physics, but it uses entropy and quantum principles to reimagine time in a new way.
The film ultimately rejects free will, presenting a world where the future dictates the past as much as the past dictates the future.
Whether or not real physics allows for inversion, Tenet offers a fascinating thought experiment about time’s reversibility.
Would you say this fits into your interest in posthuman issues (物的反撲，人的退位；物的復位，人的歸位）？The film suggests a decentralized agency, where people are not fully in control of their own causality, aligning with your exploration of human displacement in the face of greater structures - entropy, physics, AI-like determinism.
