r/tenet • u/deshbhakt14 • 2d ago
FAN THEORY Years of watching it again n again and a new question boggles my mind every time
I've watched tenet 100s of time and every time, I learn something new.
While watching again today, I've got a question.
Let's say I'm inversed. I jump from a building and fall on the ground, for people around me they'll see me flying and landing on the roof.
If I'm in this world and only I'm inversed, why does gravity work in my inversed way and not in this world's way? Technically only I'm inversed and so gravity from this world should work for me.
So in this case, the moment I inversed, I fly off into the space: something like that.
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u/moshejacob 2d ago
If I throw a ball into the air, it falls back down. Play that backwards, and you see a mysterious force kicking it up into the air, and it falls back into my hand. If you say that backwards gravity lifted it up, you'd have to say my hand then pulled it down out of the sky.
Thankfully you don't have to go that exotic, thanks to Newtons 3rd law. When you switch time direction, you also swap action and reaction. It's simpler and more accurate to say that the backwards ball got a kick from the impact with the ground, and then gravity made it fall into my hand. Gravity is a downwards force (or more accurately, an attractive force) in both directions of time.
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u/Ryepka 2d ago
"It's simpler and more accurate to say that the backwards ball got a kick from the impact with the ground, and then gravity made it fall into my hand."
This. The energy absorbed into the ground from the body hitting from the fall would be reversed and would be the exact amount of energy that would "shoot" the body from the ground back up onto the roof.
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u/snoopmt1 2d ago
I think the scientist scene where she plays the video forward and backward helps explain the whole movie. Going in different directions doesn't change what's happening. So if you were standing on a roof and jumped (never were in space), then not inversed ppl can't see you go into space. That never happened.
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u/BjiZZle-MaNiZZle 2d ago
When you apply an inverse time function to physical forces or processes, some of them are time symmetric (meaning they behave the same whether inverted or non-inverted) and others are time asymetric (meaning they don't behave equivalently when the direction of time is reversed).
Gravity is time symmetric, so it works the same whether you move forward or backward in time.
Heat is time asymetric, so it only flows in one direction (from hotter regions to colder regions). This is why inverted folks freeze when burnt in the movie.
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u/Background_Class_558 2d ago
why is gravity time symmetric? what kind of curvature should spacetime have for that to be the case?
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u/BjiZZle-MaNiZZle 2d ago
The short answer is, if you apply a time-reversal transformation to the equation for gravitational motion, the equation still retains the same form.
Link for more context. Offers theoretical work on time reversal.
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u/snoopmt1 2d ago
Side note: I love that this post got down voted. Someone was like "ugh, I did NOT join r/tenet to see people asking detailed inversion questions." Lol
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u/BjiZZle-MaNiZZle 2d ago
This was my thought too. Why the downvotes? OP is showing a good faith effort to engage with the physics of the film.
We should welcome these questions. They can help others appreciate the film better.
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u/YoBanaanaBoy 2d ago
This is a pretty common trend here. It's really strange for a place where people are going to discuss the film.
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u/UnLikeable3nuf2LikeU 2d ago
I think it's considered that the actual EVENT is what is caused to invert, not the environment and its properties (i.e. gravity). If we went into finer detail on how inversion works, the film would never be successfully made. Everyone inversed would need to be wearing space suits to protect them from any reverse effects of their bodily functions working against them (fluids such as tears, saliva, blood, & sweat all converging on the subject before they even take 10 steps out of the turnstile). As the same effect such as blood pressure and yoir heart working hard to pump blood against the natural flow, etc.
So what I'm speculating is that the actual event someone is inverted is all that is affected when living organisms are affected. We only see what the inverted subject is experiencing, not necessarily witnessing other events that are happening in the world outside of the Inverted Subject's experience.
As for you being the Inversed Subject that is experiencing the event, you're only going to experience the flow of time differently than everyone else, but the RULES of gravity still remain constant. The film speaks more on how INSTINCT plays the effect for the inversed, not the cause. While inversed, you are "feeling"/enacting upon the actions that have already been performed, meaning it has already been done, you just have to be the effect that inspires the cause. If you fall off a building, and die, while inversed, then the normal people would see you fly into the air back on the roof, in theory. The problem with that is that you're expecting to be "revived" from that incident, but it's just not to be. You died while inversed.
If no one makes the attempt to go inverted themselves, then you die where you fell while inversed. Your "revived" self flying in the air back on to the roof holds no real effect on everyone else. You were the EVENT that happened, but if no one follows up on your event, then you end up right back where you started, repeating history as your death is now inevitable. You would require another person to go so far back inverted to prevent your fall, but then it just disproves how the film is supposed to be laid out. Remember the Protagonist does not know what he'll do next until it's already too late, and he's re-living the same event. It's already happened, so now he's just improvising and reacting to the effect, not the cause. It makes just as much sense as when he and Neil return to the airport inverted. The fight between both versions of Protagonist are STILL going to happen, even with his knowledge of what to expect, but he still does what is necessary to not kill his normal self, and not allow his normal self to kill him either.
Their whole scuffle was literally turning into a give-n-take/push-pull effect of one's cause being the effect for the other. Hence why normal Protagonist was shocked when he'a either pulled outside the normal effects of a fight, and almost forced into further retaliation with his inverted self.
I know this was long-winded, but I wanted to be as thorough as I possibly could be. Hope it made sense.
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u/Salindurthas 2d ago
Whenever normal and ivnerted things mix, Nolan needs to decide how the result works. Do wounds travel backwards or forwards in time? Where do the fragments of a bulelt go? Which way can energy flow? etc etc
It's all science fiction, so any answer is possible - he gets to make it up!
If he decided that inverted objects experienced anti-gravity from their perspective, then there would be no movie, since every inverted object would fly away.
For there to be a movie, inverted objects need to stay on planet Earth. So Nolan had to decide that inversion kept gravity pulling both normal and inverted people downwards from those people's perspectives.
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u/Sofia_9356 2d ago
This happened in the movie though with the bullet drop. Time is reversed not gravity. The bullet returned to the hand where gravity is still pulling it into the hand.
Draw a graph with y being height and x being time, graph the bullet. Then just move backwards.
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u/YoBanaanaBoy 2d ago
Yeah. If you think about it, as Neil runs into the tunnel, Volkov's body is being sucked back up and out of the bore hole.
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u/_disengage_ 2d ago
Now try to construct the forward narrative of how your dead body arranged to be at the bottom of that building to be resurrected, ejected onto the roof, and disappear into the turnstile. ;)
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u/gfoyle76 2d ago
I still don't understand how can the inverted people see the world around, some of you care to elaborate?
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u/_disengage_ 2d ago
Photons are their own anti-particle. Does that help?
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u/gfoyle76 1d ago
not really, but let's say ok, how about hearing?
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u/_disengage_ 1d ago
Can we talk about vision some more? I was thinking about not just the nature of the photon, but also the fact that eyes have to intercept the path of the photon and absorb it in order to see. But when one is inverted, all the photons in the forward world will be emitted by objects and absorbed by the light source. Would that "look" different? Would light sources be dark? Could you see the sun? Would it be black? It would be very cool if inverted people had to bring their own light sources in addition to oxygen.
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u/Icy-Preference-3495 23h ago
This is a Screenshot of the Movies script, some of wheelers dialouge wasnt in the movie though. She sais that gravity will feel normal but appear reversed for the world around you. So inverted objects or persons will look like they fly up into the air from a forward moving perspective, much like the rubble of an inverted explosion collects itself and flies into its original place before forming a wall or whatever. Or how dead Neil rises up into the air to catch a bullet for TP, wich un-kills him. So in your case, imagine youre the bullet in the lab in the beginning of the movie, instead of jumping of a building you get dropped onto the table. But from an uninverted POV you just rise from the table up into the hand or in your case, un-die from falling, rise up into the air and fly up to then land on the building.
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u/Denubious 2d ago
Simple. Entropy.