In the first half of Tenet, there is a scene where The Protagonist and Neil break into Freeport and find a glass wall with bullet holes (could only find a good photo with Christopher Nolan in it):

characters standing, looking at a  a glass wall with holes

In the next scene, we find out that these bullet holes were caused by an inverted armed man entering the room (exiting the room from their perspective) and reverse-shooting the glass, which removes the bullet holes from the future-facing perspective. This all makes sense, but raises a question: how long were the bullet holes there in the first place? Were they in place as soon as the glass was installed, possibly years ago? Or even back when the glass was manufactured?

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    we should not pick on every detail of this movie or think hard on it. The same question can be asked about how long is the BMW back mirror broken? How long is the inverted bullet embedded into the wall of the Opera house?
    – Yu Zhang
    Sep 15, 2020 at 22:22
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    This was my first question after seeing the movie. If this can't be explained then the entire movie doesn't make sense IMO
    – Kidburla
    Sep 20, 2020 at 20:50
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    @Kidburla IMO the movie would make a lot more sense if it wasn't a fixed timeline and every inversion created a parallel universe. But with a fixed timeline it gets a lot more tricky. Sep 20, 2020 at 21:01
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    @Kidburla lol you want somebody to explain how entropy can be reversed? Whoever does that is definitely getting my upvote together with the Nobel prize.
    – ruslaniv
    Sep 27, 2020 at 6:53
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    @JonathanReez Could be, but I see why Nolan chose closed loop. With branching universes they can always go back and try and save Neil for example, but with closed loop, he always dies. It bears a lot more emotional weight and meaning from story telling prospective.
    – ruslaniv
    Sep 29, 2020 at 10:42

5 Answers 5


To me it seems like the other answers to this question so far are wrong; at least based on what the film is telling us about the physics of what's going on.

If one tries to take the approach that the objects are manufactured with "defects", a simple watching of the film makes it clear that doesn't seem to hold true at all, some examples being:

  1. This doesn't explain how the affected objects, such as the cracked glass or car mirror, tend to only get these "defects" right before the point in time when the inverted object impacts them.

  2. Something like the building at Stalsk-12 clearly can't have been "manufactured with a defect" of having been blown to pieces.

  3. It obviously doesn't work for humans, such as Neil, who can't be "manufactured" with the defect of a hole in his head and lying inside a bunker.

To understand what's actually happening, one must consider what Neil says in the scene where you get the most explaining of the physics (even though it's not much), which is when he and Protagonist are inverted with Kat on the boat as they are headed back to the airport to reinvert themselves there. In this scene Neil describes why Protagonist survived:

But because the environment's entropy flows in our direction we dominate. They're always swimming upstream. It's what saved your life—the inverted explosion was pushing against the environment.

This is what Protagonist humorously refers to as "pissing in the wind".

In other words, wherever you have inverted objects attempting to impact regular objects, their effects will tend to struggle against the greatly dominant entropic direction against them, which will essentially work to erase their impact. In fact, not only will their impact be erased, but the entire object itself will with time be whisked out of existence completely, presumably along with an equal portion of regular matter, and taking more time to do so. I'll get to some more about that later.

Think about it in terms of the aforementioned examples of the glass and the car mirror from the inverted perspective: we see that from the regular perspective, the glass and mirror seem fine, until they slowly start cracking as the event of impact approaches, at which point they're suddenly fine once more; this means that from the inverted perspective, the inverted bullet hits the glass and the car hits the mirror respectively, both cracking them, but with time the entropy of regular objects work against and erase their impact until they disappear completely. The exact same is true for the building at Stalsk-12, except it's destroyed in regular time as well immediately after the inverted impact (which would be like breaking the glass/car mirror right after it "fixes itself" in regular time upon encountering the inverted object that broke it); what isn't shown is what happens to the building before being destroyed in inverted time, i.e. before the events of the battle in regular time, which would be the building, just like the glass and car mirror, going from its intact and standing state and breaking apart out of nowhere to leave it in the state it's in after the inverted destruction.

To try to illustrate these three examples more clearly, here's a breakdown of each from the perspective of regular time:


  1. Gets manufactured fully intact.
  2. Slowly starts to crack out of nowhere, and the inverted bullets also appear out of nowhere over a longer period of time.
  3. The bullets fly back into the inverted gun through the holes in the glass, instantly fixing them as they do so.
  4. Is once again fully intact, just as it was manufactured.

Car mirror:

  1. Gets manufactured fully intact.
  2. Slowly starts to crack out of nowhere.
  3. The inverted car hits it and it is instantly fixed.
  4. Is once again fully intact, just as it was manufactured.

Building at Stalsk-12:

  1. Gets manufactured fully intact.
  2. Slowly starts to crumble and fall apart out of nowhere.
  3. Gets hit with inverted rocket launcher blast, instantly fixing it.
  4. For a brief moment is once again fully intact, just as it was manufactured.
  5. Gets hit with a regular rocket launcher blast and is destroyed.

Hopefully this makes it clear how those things are supposed to work.

Perhaps the hardest thing to swallow about this explanation is what I briefly mentioned above, i.e. the entire "disappears into nowhere" and "appears out of nowhere" part, but it really does seem to be how it works. To me it seems implied that inverted objects interacting with regular objects will seem to shift each other into a direction of time that's not parallel to either, thus seemingly disappearing completely from our view (but perhaps recoverable through an even more advanced future understanding of physics), or in the other direction appearing out of nowhere. There are at least two prominent points that come to mind to suggest this is indeed the case:

  1. Wheeler warns about not touching your inverted self, as it would lead to "annihilation"; this is of course specifically about yourself, but in the same scene is also when we're introduced to the point of needing inverted oxygen to breathe as well, strongly implying that trying to inhale air that's inverted from your perspective could be very dangerous. In any case, the phrasing "annihilation" seems to allude to the type of "annihilation" that occurs when matter meets antimatter.

  2. The turnstiles clearly make it seem like objects either appear out of nowhere in one direction of time or disappear into nowhere in the other; i.e. when you use a turnstile to invert something, you will see it move into the turnstile on the other side as well, and if you remain outside the turnstile, both will have disappeared into nothing, whereas if you're standing outside a turnstile as someone is inverting from the other direction of time, they will appear out of nothing. This is the most telling about how the objects are not really appearing or disappearing, but "simply" changing temporal direction, seeming to us to disappear due to how we continue in our own temporal direction.

To me it seems like this is clearly how the physics are supposed to work in the film, both as explained and as shown in the various events.

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    This is a great answer in my opinion. Its the only way that I personally can think about the premise of this movie without ending up in ridiculous conclusions like you outline at the start.
    – iandotkelly
    Nov 15, 2022 at 15:30
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    The other answers that go down the path of the hole in the glass is somehow formed as the glass cools doesn't work at all - so they installed glass with holes it it? The building was somehow assembled as rubble? Ridiculous. That said, the bullet holes clearly don't form slowly a person who is shot? Clearly that happens only in a few seconds (or less) rather than hours and minutes, so why don't we see that with holes in glass or rubble of building.
    – iandotkelly
    Nov 15, 2022 at 15:36
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    All in all this movie requires much more of a suspense of disbelief than many, even other Nolan movies. I guess it has driven much more conversation about its premise than many though.
    – iandotkelly
    Nov 15, 2022 at 15:38
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    @BestGuess No, in inverted POV, yes in regular time POV. In regular time POV, you literally see inverted Neil go back to life after being shot with a non-inverted bullet, which surprised the shooter. The examples the answer OP gave were all of regular time objects, so they don't apply the same way to inverted Neil. Inverted Neil is "pissing against the wind"; his death can't be undone. "[...] the entire object itself will with time be whisked out of existence completely" Nov 17, 2022 at 4:04
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    Where did you hear Wheeler say "extinction"? In my version of the movie (2:30:09 long) she says "annihilation" at 1:29:56.
    – Greendrake
    Nov 18, 2022 at 9:15

Questions like this do touch the nerve of the film's logical consistency.

In our normal, non-inverted timeflow, when you shoot a wall/glass, the resulting hole remains in it indefinitely and only gets worse with time. It will eventually get buried/destroyed after the building gets demolished. The hole will not magically self-heal / disappear.

In Tenet's inverted timeflow the laws of physics are deemed to be all the same. It's just the entropy/time that flows in the opposite direction. So, there should be no reasons to presume that the behaviour of a bullet hole shot by an inverted round would be any different in its timeflow. Like with a normal bullet hole, it should be worsening with its time going forwards (ours backwards), not self-healing.

What that means is that, logically, the hole got formed it its worst/oldest state in the glass right when it was solidifying from liquid silica at the glass factory. Yes it was essentially a factory-made flaw/defect which, for whatever reasons, was ignored by the factory's QA, glass supply chain, the builders and the Freeport vault staff all the way along. Think they all were on Tenet's payroll or whatever.

Like Barbara said to the Protagonist: "Don't try to understand it. Feel it". I don't think Christopher Nolan intended to make it completely logically consistent and making sense. It's just supposed to be a "wow" to impress the majority of viewers who will simply say "Ingenious! Let's go see it again, maybe we'll understand some more".

  • Okay, so if you get shot in the head with an inverted round.. are you born with a bullet in your head? And somehow you manage to live through your entire life with this bullet in your head somehow alive, walking up to a guy one day who then unshoots the bullet from your head? Feb 2, 2021 at 2:01
  • @JemarJones If you were to get shot with an inverted bullet in your head, it would have been flown through your head in and out. But otherwise, yes, your example just demonstrates what nonsense the film is.
    – Greendrake
    Feb 2, 2021 at 4:13
  • "...impress the majority of users..." Great point. Thoroughly unimpressed with this crud. Feb 21, 2022 at 18:26
  • The glass isn't inverted, only the bullet. The bullet gets fired into the glass and it makes a hole, but the worsening of the hole isn't inverted.
    – shim
    Aug 7, 2022 at 2:06

The in-universe explanation is that traces of all interactions between inverted and regular objects were always present in our universe. What has happened - happened.

So as soon as the glass was made it was already cracked, although the cracks were microscopic. Then they would grow larger and larger until they form a complete bullet hole at some time prior to the event.

All this is clearly explained during the inverted trip to Oslo.

  1. When the inverted Protagonist, Neil and Cat board the container, it is specifically shown that the Protagonist's right biceps is bothering him.
  2. During the trip, judging by Protagonist's emotions, it starts bothering him even more.
  3. When they arrive at Oslo airport, it is bothering him so much that Protagonist rolls up the sleeve and looks at his arm. We can see that there is some kind of a bruise on his right biceps.
  4. Just a few seconds prior to leaving the container, Neil sees blood dripping from Protagonist's right arm, but they have no time to investigate.
  5. From that moment, it is about 20 minutes give or take until he gets stabbed exactly in his right biceps.
  • But then, isn't the timeline violated from the inverted perspective? They would see the glass spontaneously self-repair sometime after they've shot it. Sep 30, 2020 at 16:28
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    @JonathanReez Protagonist shot the glass while being inverted so from his prospective the holes were the results of him shooting the gun. And from a normal prospective, yes, the glass would "self-repair", that's what we see during the first fight scene, shown from the normal prospective. Same with the BMW mirror, as soon as inverted Audi clips it, the mirror becomes unbroken.
    – ruslaniv
    Sep 30, 2020 at 16:41
  • What I meant was - imagine an inverted protagonist shooting a glass and staying inverted to watch what happens. Would the glass spontaneously self repair a few hours after he shoots it? Sep 30, 2020 at 16:51
  • @JonathanReez Ah, I see what you mean. Yes, based on the closed loop under which the movie operates, he will see the bullet holes fade away.
    – ruslaniv
    Sep 30, 2020 at 16:58
  • @Rusl but then, shouldn't the gold sent to Sator have faded away quickly, rather than going all the way back to the past, similar to the bullet fading away? Sep 30, 2020 at 17:08

The movie shows the glasses cracking just moments 'before' they're shot by the inverted agents. This means everything that happens in the inverted entropy world ends up being 'erased' by the forward timeline. So, the holes were there just for a brief period.

The holes in the holes logic

But this theory brings us several other questions. My guess is Nolan had this idea for the movie and then started to notice the problems, which he tried to address without fully succeed. Let's see:

1.As you stated, if the inverted-bullet hole is present before we entered the room, then it must've been there forever since the glass was fabricated and installed, which doesn't make sense. Nolan tried to solve this by showing - from the normal-entropy perspective - the cracks slowly forming just moments before the glass was (or will be) shot by the inverted-bullet. This, of course, leads to the unexplained problem of what happens to the inverted-bullet itself. Does it simply appear from nothing from our perspective and disappear for the inverted-person perspective? This doesn't seem to be the case, as in the beginning of the movie we're shown that several bullets and other inverted-stuff have been found all over the world.

2.The backwards wall and glass holes gives us a very nice cinematic effect, but I think they are there to also hide another implication of Nolan's idea. What if the inverted-bullet gets lodged in the victim's body? If we go by the same logic of the glass holes, then the wound of the shot should gradually appear in the victim's body moments before they're shot. Again, Nolan tried to address this issue by showing The Protagonist's arm getting slowly wounded as they were inverted-traveling in the boat to Oslo, up to the point when he's finally stabbed by the normal-oriented himself. But, this doesn't happen to anyone else in the movie. Just like the glasses, all the people shot in the movie should've started to notice a inverted-bullet hole starting to grow in them for at least some time before they're finally dead and probably even be dead moments before the inverted-bullet finally trespassed them.

3.The two points above bring an even weirder question, absolutely not addressed by Nolan. If, from the normal perspective, bullets and holes gradually appear just before the shots, what would happen to the bodies of the inverted dead-people? Would you see a body gradually forming? For how long would they be lying there? And from the inverted perspective, would the bodies slowly decay or simply disappear, just like the holes?

4.If from the inverted-perspective the bullet holes disappear in time, what happens if a inverted-person interacts with the normal-world and builds something, instead of destroying it? Let's say I'm inverted and then I build a house. Would that be possible by Nolan's logic? It seems that from my inverted perspective the house would disappear just like the holes. So, what would a normal-perspective person see? A house being inverted-built from nothing? Again, where does all the matter/energy for this come from? Nolan throws an explanation to this during the inverted-boat sequence, when Neil argues that all inverted-entropy elements "fight" against the normal ones and get eventually obliterated, which The Protagonist jokingly calls "pissing against the wind". This, of course, would lead directly to the grandfather paradox. If the future people succeed in activating the algorithm and obliterate all past, they'll eventually kill all of their ascendents and never be born in the first place.

These, for me, are just the main problems with the movie's logic. There are others that Nolan try to bypass with characters statements like "don't try to understand it" and "what happens, happens". I guess that's what we gotta do if we want to enjoy the movie and not be annoyed by its inconsistencies.

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    +1. Nolan's main miscalculation was that most of the audience who would be annoyed by the inconsistencies simply won't be able "not to think too much", and so will remain annoyed; conversely, those not disposed to think too much won't get the movie at all, and thus won't enjoy it much.
    – Greendrake
    Feb 21, 2023 at 14:03
  • It appears that your post is more of a discussion or rant rather than a direct answer to OP's question. Could you provide a summary of your answer that directly addresses the OP's question? Feb 22, 2023 at 0:52
  • @galacticninja, you're right. I ended up bringing more of a discussion than a sensible answer. I'll try to summarize it. Feb 23, 2023 at 16:31

Yes, those bullet holes have always been there since the glass was manufactured. From the inverted perspective, the building is eventually dismantled and the glass is driven backwards in a truck back to a factory then is melted down into sand.

According to the principle of "whatever happened, happened", the fact that the bullet holes are there, it must mean that they were installed that way. If there was, for example, a fastidious contractor who would have noticed the holes and thrown it out, then the original shots could not have ever happened. This is similar to how they looked through the window to see if their inverted selves were going into the turnstile. If you decided not to go into the turnstile, then you wouldn't see your inverted self going into the turnstile either. Or similarly with the inverted rounds jumping up into the characters' hands. It seems implausible but the construction of the room is not shown to the audience and you could come up with any explanation for why those holes are there.

There's a great novelette called "The Merchant and the Alchemist's Gate" by Ted Chiang:

In it, a character has a hoop where one side is delayed relative to the other. If you put your hand in one side in you see your hand come out the other side a minute later. If you put your hand in the other side your hand comes out the other side a minute earlier. If you see your hand come out that side of hoop you will inevitably be putting your hand in the other side in one minute. If you decide you would not do that then your hand wouldn't have shown up in the first place.

If you manage to shoot someone and the bullet is embedded in their body, then you follow that bullet back to the person's birth, eventually that bullet is too big to fit inside that person. Either you have a paradox since the bullet is going to kill that person before they're old enough to get shot by that bullet (and one way to look at it is that the paradox could not happen therefore it's impossible for the original shooting event to have occurred), or the bullet falls out at some point without killing the person. So in the forward perspective you have a child walking along when a bullet suddenly jumps up off the ground and embeds itself in their body. This is just a contrived example; it's not intended as a full explanation.

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    Honestly, this approach to the premise makes no sense to me. So they install glass with bullet holes in it, and people just accept that? Also bullets don't just 'fall out of people' .... so either the bullet is in them their entire life, or ....?
    – iandotkelly
    Nov 15, 2022 at 20:28
  • Don't blame me, blame the movie. They repeat it over and over "whatever happened, happened." I don't know why they would install glass with bullet holes in it, but you see them so they must have. This is a universe in which the flow of time can be reversed. So why is the fact that someone installed windows with bullet holes in them so unbelievable? You don't agree with the explanation then fine, don't upvote it… but why do you feel the need to downvote it?
    – shim
    Nov 18, 2022 at 5:10
  • Same thing with the example of a bullet in a body. If I'm reversed and I shoot someone who isn't reversed, then it would be paradox if that bullet killed them when they were a child. So within the rules set by the movie, something else must have happened, and that could be pretty much anything. The example of the bullet falling out of the person is just one possible way to resolve the paradox. Nothing like that was shown in the movie so it's purely hypothetical; though a bunch of people do get shot especially in the final battle, so clearly it's something to think about.
    – shim
    Nov 18, 2022 at 5:22

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