This review will be analysing the movie “Tenet”, explaining the logic behind its complicated timeline.
“Tenet” is written in a complicated setting, which is crucial for comprehensively understanding the storyline. In the future world, the environment of Earth will be severely worsened, human beings will be on the edge of extinction. The future humans came up with a solution: if the people from the past are wiped out, then all the other plants and creatures on earth will emerge again as they no longer have to endure the persecution from humans, and the Earth’s environment in the future may be saved, because the future humans think that it is the people from the past of the earth who have caused the devastating situation on Earth. This manipulation towards timeline recalls the famous grandfather paradox: if you go back to the past and kill your grandfather, how can you still be born, and if you were not given birth, how can you kill your grandfather? This forms a paradox of looping logic. But the future human believes in the theory of parallel universe: eliminating the past human can create a new parallel universe. And even if the future humans are eliminated due to the death of the people in the past, it does not matter, as they would soon become extinct anyway as the result of the polluted, uninhabitable Earth environment.
So Laura, a scientist in the future world, created the “algorithm” — a doomsday machine that inverts the universe. However, after creating the Algorithm, Laura regretted it. In the film, there is a brief explanation of her regret, comparing her to J. Robert Oppenheimer, the “father of the atomic bomb.” When Oppenheimer developed the atomic bomb and witnessed its devastation in Hiroshima and Nagasaki, he lamented, “Now I am become Death, the destroyer of worlds.” Similarly, Laura believed she had opened Pandora’s box, leading to more harm and death. To prevent further destruction, she dismantled the Algorithm into nine parts and, using inversion, hid these parts in the nuclear weapon safe rooms of nine nuclear-armed countries. These countries are China, the United States, Russia, the United Kingdom, France, India, Pakistan, North Korea, and Israel. After hiding the Algorithm, Laura took her own life.
This sets up the subsequent story: people from the future, in order to retrieve the Algorithm, needed to select someone from the past to execute their plan. That person is the film’s main antagonist, Sator. The people from the future made a time capsule containing gold bars and a letter addressed to Sator, instructing him to help them recover the Algorithm and trigger the doomsday. The time capsule was buried in a nuclear-polluted site. They chose Sator because they already knew that Sator was most likely going to get an incurable illness for making a living in the nuclear-polluted site, where the radiation would impose irreversible genetic damage. This illness would make him desire the world to die along with him.
This creates two opposing forces: the future human desperate to erase the past world, who act through Sator to collect the pieces of the Algorithm and set off the explosion, and those trying to prevent this catastrophe. The other side is led by the “Protagonist” —a future person, they are the ones on Laura’s side, who do not wish to see the past world destroyed. They are committed to preventing this catastrophic event from occurring. Later in the film, the Indian arms dealer Priya is revealed to be a descendant of the Tenet organization. As for the present-day Protagonist, he is in fact a different version of his future self, on the mission of stopping everything from happening. However, he doesn’t carry the memory of his future version. It is interesting how John David Washington’s character, the Protagonist, has no name from the start to the end. His name is never introduced, and no one calls him by a name. Even when interacting with others, names are avoided, making him seem like a nameless, faceless person living anonymously. Nevertheless, he is the mastermind and executor of the entire Tenet operation. This anonymity creates a sense of mysteriousness, which reinforces the audience’s awe towards his omnipresence throughout the timeline and his capability of planning such a complicated rebellion.
Beyond the overarching structure of the movie, the physics concepts involved are also crucial to understanding the complicated plot line of this story. Time inversion involves entering a machine and reversing the flow of time to move into the past or the future. However, once inverted, everything is experienced in reverse—for example, what feels warm to others would feel cold to you, and while others move forward, you would appear to be moving backwards. A key detail in the movie is that when inverted people fire a gun, the bullet holes appear on the glass before the gun is shot, and then the holes disappear after the shot. This “reverse bullet” effect demonstrates their inversion within the flow of time. The principle behind time inversion lies in the manipulation of entropy. In physics, entropy describes the directionality of processes: disorder increases as time progresses (entropy increases) while moving toward order involves decreasing entropy. The people of the future exploit this principle to develop the turnstiles (inversion machines), allowing objects and people to reverse their entropy. When the Protagonist enters a turnstile, his entropy changes as the machine rotates and seals. Upon emerging from the opposite door, he experiences the inverted flow of time.
Another detail is the significance of red and blue in the turnstiles. This ties into the CPT symmetry theory in physics, a fundamental conservation law. Where C refers to replacing particles with antiparticles, P refers to taking a mirror image, swapping left and right, and T refers to reversing the motion of all particles, effectively moving backwards in time. This explains how in the film, entering the red door and leaving from the blue door puts you in reversed time, while repeating the same procedure in the opposite sequence: entering the red door and then entering the blue door, places you in inverted time.
Aside from the time machine, there is another crucial invention in this movie, which is the “algorithm”. It is an advanced extension of the inversion technology, capable of inverting the entire world. If activated at a specific point in time, it would annihilate the past world. It may erase environmental destruction and provide relief to future generations, or it may also eliminate the future world. However, this repeated inversion introduces immense complexity, making the film incredibly challenging to follow. Unlike traditional time travel, experiencing inversion comes at a high cost. When you enter inverted time, there can be three versions of yourself moving simultaneously: the future “you” trying to change the past, the inverted “you” acting in the present, and the past “you” in the original timeline. This overlap results in a tripling of time experienced. For instance, if the future “you” wants to alter the future, you must invert yourself to go and inform your past self, the inverted “you” eventually returns, having undergone a 3x extended timeline.
The film also repeatedly mentions the time pincer movement, where events are coordinated from both regular and inverted timelines. Neil frequently reminds the Protagonist that “ignorance is the greatest advantage” and “what’s happened, happened.” This philosophy reflects the Tenet organisation’s belief in maintaining the integrity of the timeline. Knowing too much could introduce unpredictable chaos and jeopardize the mission. For instance, Neil doesn’t reveal everything to the Protagonist because he understands that the latter needs to trust his instincts and solve problems without overthinking the consequences. The organization relies on this balance to ensure events unfold as intended.
Lastly, there are some meticulous details displayed in the movie. One poignant moment occurs when Neil orders the Protagonist’s favourite drink during their first meeting, a subtle sigh signals his deep familiarity with him. Later, Neil’s questions: “Would you hijack a woman and child?”. This reveals his prior knowledge of their upcoming plan involving Kat and the eventual confrontation with Priya, though he avoids disclosing too much, there is enough evidence for the audience to suspect that Neil was reversed from the future. We are eventually informed at the end of the movie, that Neil is indeed a close companion of the future protagonist, as Neil executes his faith of walking on his fatal mission, we see this beautiful friendship that has not even started for the protagonist, ending for Neil.
The lack of clarity in the first half of the film makes the plot challenging to follow. However, as the mysteries unravel in the latter half, the intricate connections and looping sequences provide a satisfying sense of coherence to the audience. This complicated logic is also what makes this movie so intriguing, greatly contributing to the movie’s eventual success.