TENET Time Inversion Explained

Tenet is packed with a lot of Time Wimey Wibbly Wobbly stuff and you’d need more than a Doctor Who had a PHD in Theoretical Physics to understand the process of how it works in the film.

However, we’ve gone over the movie back to front to figure out all its machinations and how everything comes together to form one cohesive loop in which the future relies on the past just like how the past relies on the future.

There will be heavy spoilers here so if you haven’t checked out the film yet then I recommend that you turn off now.

What is Time?

Before discussing time in the film we have to discuss time itself.

Time is a strange old thing and even scientists are still not 100% sure how it exists, what was before it and what caused it.

When did time start? Does it stretch back trillions of years? If so does it have a starting point and if it does, does that mean that it also has an endpoint?

All these questions could completely rot your brain and it’s best to not dwell on them too much as we simply don’t have the time to talk about time itself.

In its most basic terms though, time is the progression of existence in which we move towards the future from the present and in doing this create the past.

This sequence seems irreversible and because of the way that humans perceive time we witness them happen linearly.

However there are theories that time is actually cyclical and if we were to view time all at once we would see how everything fits together in one complete sequence in which all things exist at once, relying on each other to create a complete experience.

Time Inversion Explained

Now, what Tenet does is that it takes how we view time and flips this through a process called time inversion.

So instead of viewing time moving from the present into the future it inverts this perspective and allows objects and the characters to move through the flow of time from the present into the past.

Now there are no real jumps in this and the flow of time still moves the exact same way. So 10 years backwards is still the same length of time to the person who is inverted as 10 years forward would be.

How Does One Invert Time

Now how is this accomplished exactly? Well, all humans and objects have something known as entropy.

In physics, entropy is a thermodynamic quantity which represents a system’s thermal energy which changes over time. Entropy is a measurement used to disguise the past from the future and it tends to work in one direction only. However, due to radiation, scientists in the future can reverse this.

This is accomplished through a process that involves radiating objects.

Now though this is never said, it likely ties into tachyons which are theoretical particles that are capable of moving faster than the speed of light. This means that they cannot be fully observed and they may be able to move backwards through time.

Though we learn very little about the scientists in the future that have created this method of applying radiation, they have clearly found a way to reverse the entropy of objects and people.

Thus instead of travelling forwards, they start to move backwards and because we are conscious beings the characters in the film can experience time moving in the opposite direction.

Can Time Be Changed?

Moving through time is not something that the characters can actually control and because the past happened the way that it did which led to the characters eventually having to reverse themselves, the past will still play out the same way that it did with the characters merely gaining a new perspective of it. The cause and effect leading to the event will always be the same way and thus it is impossible to change it.

We even get a brief hint of this in the movie when we see Michael Caine’s character…who I think is also called Michael…explain that two weeks before their meeting, the Sator operation happened at the site we see in the finale of the movie. This was during the opera house assault and it’s something that you only catch on a second watch that actually spoils the end of the movie and lets you know that he failed.

Time Travel Theories 

Now though the film initially dabbles in the idea of the multi-worlds theory by the end it sticks firmly with the idea that everything that happened has to happen and will happen. This removes the idea of the grandfather paradox which is a theory that has existed in the idea of time travel probably since time travel was first thought up.

The grandfather paradox says that if you went back in time and killed your grandfather before he had created one of your parents that you would be unable to do so because you would therefore not have been created to go back and kill your grandfather.

Thus everything must happen the way that it does to avoid creating a paradox.

We even see examples of this in the film when our Protagonist ends up encountering himself at Sator’s vault and their fight plays out the exact same way, completely unchanged.

No matter what, the characters will go through the motions and the events will always play out the exact same way.

The most definitive examples of this come at two key points in the film. Firstly is when Sator enters the inversion machine. He requests that his contact on the outside tells him to relay the events of the car chase exactly how they happened so that when he goes out there he will follow the motions that led to his inverted self on the outside carrying out actions which he believes gave him a piece of the algorithm.

Another key point is during the final battle, we see that the inverted team have to remain inside shipping containers whilst the forward-moving team do not. This is because they have already completed the mission and if the team about to go in saw what had happened to them it might change things.

In both instances, this is called a temporal pincer movement in which one can learn information about an event, then invert oneself and travel back in time to carry it out creating a perfect loop.

How Are People Reversed?

This is difficult to get your head around but it does follow the rules of cause and effect.

The film also gives little key nods to who is inverted and who isn’t through its use of colour, when the protagonist is kidnapped by Sator we see that the forward moving area is red whilst the reversed is blue. This is also later adopted in the final operation.

As for how people are inverted this is actually due to a machine that was created in the future and then was inverted and sent back. It’s not so much a time machine in that it is basically just the uno switch card that points you back instead of forward.

Timelines

Now because of the way that the film works, there’s a lot of confusion over the timeline that certain characters go through. Kat is probably the one that people are most confused about so she will be our main player as we discuss it.

Kat’s Timeline

Now the first major key event for Kat is the time on the boat with her husband. Initially, they are happy and Kat travels to shore with her son, upon returning home she sees a woman diving off the boat. Her husband is not there but she suspects that he’s having an affair and slowly begins to hate him. She goes through the events of the film, meeting the protagonist, setting him up with Sator and then she is taken captive and shot by him.

Sator believes that she dies from this because to his knowledge there is no way to treat an inverted bullet.

However, the protagonist and co invert themselves and Kat and heal her all whilst travelling back to the turnstile that we saw at the art gallery.

Going Back to Kill Sator

Here they revert back to normal and travel forward for a bit whilst they discuss Sator’s plan. Kat and the group then travel back to just before the boat scene that we heard about from Kat in which she started to dislike her husband again.

Kat waits until her past self leaves the boat and then boards it, wearing the same clothes that she wore on that day to enact her plan.

Because Sator believes that the future version of his wife is dead he does not suspect her to be here and he waits until his past self leaves on a helicopter before going back aboard the boat on the exact same ride to not arouse any suspicion.

Here he and Kat talk whilst the latter acts like her past self. At the last minute, she kills Sator and then dives off the boat, setting in motion herself to see the woman her past self believed was having an affair.

The past Sator returns alive, not knowing his future self has just died and he continues as normal.

Two Kats

Now at this time, there are two Kats in the past.

The past version follows the exact same path as Kat who has just killed her husband. Moving through the exact same events that would eventually lead to her going to the boat and killing her husband.

The future version remains in the shadows, waiting until her past self goes back to the day on the boat so that she can move forward and continue her life. The loop completes itself with there then only being one version of Kat in the future and this is the one that we see pick her son up from school at the end.

Each of the characters follows pretty much this timeline structure except for Sator who doesn’t move past that fateful day on the boat.

The Protagonist would pretty much operate in this manner controlling things from behind the scene and putting the events in motion that would lead to his past self being captured at the opera house.

That’s pretty much the events of the film and once you get your head around it you’ll see that it all fits together really neatly and doesn’t have any issues which fall apart due to the nature of time travel.

Your Thoughts

It’s still pretty complex though so if you’re still confused then make sure you comment below and either I or someone smarter than me will probably get back to you.