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  • Annika Santhanam

The Science Behind Tenet: How Entropy and Inversion Work

Christopher Nolan never fails to direct mind-boggling movies filled with jaw-dropping (and heavily science-based!) scenes. In his recent movie, Tenet, released in 2020, Nolan uses the scientific principle of entropy in order to set up a new concept of inversion in the movie.

What is Tenet About?

In the movie, the main character, referred to as ‘The Protagonist’ (played by John David Washington) is recruited to essentially stop the end of the world. He learns that an organization in the future is trying to detonate a weapon of mass destruction by sending parts of it back in time to a certain arms dealer. Throughout the movie, The Protagonist teams up with another character, Neil (played by Robert Pattinson) in order to carry out an elaborate scheme to get their hands on the pieces of the weapon, referred to as the Algorithm, and stop the scheme from happening.

A big part of this movie is the concept of inversion. As mentioned before, the organization from the future is sending pieces of the Algorithm back in time, essentially contacting the people of the present. The main twist in this version of time travel is that it’s not really time travel at all – instead of jumping from a spot in the future to a spot in the past, an object (or person) is “inverted” and travels backward along the stream of time while the world around them moves forward in time. This way, if someone or something is one week ahead in the future, they can invert themselves, spend one week in inverted time, and un-invert themselves to return one week back in time. As you can see, inversion is not instantaneous time travel – whatever amount of time you want to travel back to, you must spend while inverted.

In Tenet, inversion is achieved through a turnstile. When characters enter this turnstile, they become inverted and are automatically placed on the path traveling backwards in time, while everything around them moves forward. Essentially, they are moving in reverse, though it seems normal in their eyes. The main characters in the movie use the process of inversion to carry out a huge sting operation at the closing scene to get their hands on the algorithm, a process that may seem wild at first but slowly makes sense when inversion is taken into account.

What Is Entropy and Why Is It Important in Tenet?

Although inversion is mainly an unproven concept, it is actually based on the very real principle of entropy. In simple terms, entropy is basically disorder. As time goes on, things get more disordered in the system as entropy increases. A basic example of this is when ice melts. Water in a solid form has a precise arrangement of water molecules in order to form a solid. However, when the ice melts, the water molecules spread out in liquid form and become much more disordered in the system, showing that entropy has increased.

So why is this important in Tenet? It’s because the concept of inversion is based on being able to decrease entropy. In the real world, it is impossible for the entropy of the universe to decrease on its own. If entropy decreases, then order increases, which is the opposite to how time flows. This basically dictates that if you do decrease entropy, you could possible travel backwards through the flow of time.

With all of this information, could inversion really be possible?

The immediate answer is probably not. The laws of the universe currently dictate that entropy could never decrease in a system, making it virtually impossible to make an inversion turnstile. Unless the laws of physics suddenly change in the future – or we get a new understanding of how something like this could happen – it seems Tenet is reaching farther into the future than we can see.

That’s a wrap on the process of inversion and how entropy plays a role in Tenet. I hope you enjoyed reading and stay tuned for more articles!

Source: Tenet, Explained: What’s Going On in the Plot of this Movie? (


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