2021 자율동아리 과학영자신문반 (2) _ The Science Behind Tenet

(2021 2nd semester)

        Tenet is a science fiction action thriller film released in 2020, written and directed by Christopher Nolan. The “Protagonist”, a CIA agent, after consuming a suicide pill following an extraction operation at the Kyiv opera house and being captured& tortured by mercenaries[i], awakens to learn that the suicide pill was a test of loyalty. The Protagonist is recruited by Tenet, where he is introduced to objects with inverted entropy for the first time. The Protagonist and his crew (including Neil and Ives) fight against Sator and the people of the future from inversing the entropy of the entire earth, which would lead to total extinction of almost all species.

 

        Tenet has an interesting scientific topic: time. Especially, the inversion of time and Nolan’s specific ideas on how it could be done and what would happen if time flew in the opposite way. There are a few points in this movie that are worth looking into deeply.

 

        When the Protagonist is recruited to Tenet and sees an inverted object’s movement for the first time, the scientist explaining to him says that the entropy of the objects was inverted by some future technology, and that’s what’s making them act in the opposite direction of time, and as if physics applied in reverse order for the inverted objects. There are three types of “arrow of time[ii]”: the thermodynamical arrow of time, the psychological arrow of time, and the cosmological arrow of time. In the point of view of an un-inverted person in Tenet, an inverted person would be seen experiencing the thermodynamical and psychological arrow of time pointed in the opposite direction. However, in the movie, the mechanics of time inversion is only explained by the inverted flow of entropy. The reason why reversing the flow of entropy would change the direction of psychological time seems to require further explanations.

 

        Later in the movie, the Protagonist is warned that when inverted, direct physical contact with his non-inverted self would cause the annihilation[iii] of both. This explanation is similar to the pair annihilation of a particle and antiparticle in Feynman diagrams. This is also related to the one-electron universe postulate[iv], proposed by John Wheeler. Wheeler suggested that the word lines of electrons across spacetime are the traces of a single ‘real’ electron moving through spacetime. In this idea, a positron, the antiparticle of an electron, can be represented as electrons moving from future to past in spacetime. Feynman later proposed this interpretation of the positron in his paper, and Yoichiro Nambu applied it to all production and annihilation of particle-antiparticle pairs. This approach explains the annihilation of a particle-antiparticle pair as an event of a particle changing direction of movement in the time axis of spacetime. Applied to the situation in Tenet, the Protagonist and his inverted form can be considered as one another’s antiparticle. This would explain why contact with one’s non-inverted body would lead to annihilation. Then the turnstile[v] would be a device for controlling the inversion (collision of “person-antiperson pair”) and preventing annihilation from happening by somehow absorbing the electromagnetic waves generated by the process.

 

        So far, we’ve covered the science behind Tenet. Thinking about the scientific basis of a SF movie or novel can actually help you understand the concepts and the plot of them more easily. Not only so, it’s also a fun and special (in a good way) hobby. I recommend you watch Tenet yourself find more of what’s related to science.

 

Cover image: https://www.tenetfilm.net/

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[i] mercenary(용병): a professional soldier hired to serve in a foreign army

[ii] arrow of time: a concept positing the “one-way direction” or “asymmetry” of time. The ‘arrow’ points in the direction time flows, which is the direction entropy increases (thermodynamical arrow of time), the direction space is expanding (cosmological arrow of time), and the direction of time as we feel it (psychological arrow of time)

[iii] annihilation(소멸 or 쌍소멸): the conversion of matter into energy, especially the mutual conversion of a particle and an antiparticle into electromagnetic radiation(physics)

[iv] postulate(가정): a thing suggested or assumed as true as the basis for reasoning, discussion, or belief

[v] turnstile(개찰구): a mechanical gate consisting of revolving horizontal arms fixed to a vertical post, allowing only one person at a time to pass through. In Tenet, the turnstile is a gate-like device that inverses the entropy of an object passing through it.