The Avengers: Endgame Timeline Explained (Spoilers)

Published by Darron Toy on

this is the Avengers endgame timeline explained with science even if you're not a Marvel nerd it's hard to argue that the Marvel Cinematic Universe isn't incredibly impressive as a venture in storytelling in business and in pop culture over 10 years billions and billions of dollars 22 films some of which are the most successful of all time and now with endgame this era of the MCU closes with the culmination of a truly epic arc but because Marvel has decided to be so delightfully sciency in many of its movies is there a way for us to more realistically interpret what actually happened in endgame let's figure it out I guess we're in the endgame now before we get started we are going to be literally spoiling the entirety of avengers endgame so if you have not seen the movie yet you absolutely have to turn back right now alright so by the end of infinity war Thanos has won dusting half of the universe in the process to reverse this terrible deed and to avenge all those who fell the remaining Avengers have a plan jump into the quantum realm multiple times in order to time-travel steal the Infinity stones in the past and undo the snap in the present it's a mind-bending and satisfying end to a decade-long story time travel is inherently confusing so how exactly did the Avengers accomplish this what did their path through space-time actually look like I escaped the void for a brief and beautiful moment of time just to attend the world premiere somehow of Avengers endgame with a notepad in order to take down notes in the dark to get out of video just in time for all you nerds and this is what I came up with these are the events of Avengers endgame laid out chronologically with all the weird time-travel east of going on this is what we have to science is any of this plausible with the laws of physics as we know them is Professor Hulk better than the regular Hulk we'll come back to this in a bit but not the professor Hulk thing he's much much better first let's do our best to wrap our heads around what time-travel actually is from a scientific perspective traveling to different points in time is like traveling to different points in space like I just did if this is a graph of my position I went from here to here now let's add time to the mix when I took that step it had to have occurred over some time and when I trace that path you can see that I am taking a path through both time and space but because we are talking about space-time we also need some kind of boundary here that would prevent us from going faster and further than light could in the same space-time this is our light speed boundary now if we add the rest of three-dimensional space x y&z except we are suppressing Z here because we cannot see in four dimensions we can trace every single point in space and time that you could possibly take and this is what physicists call your world line finally if we rotate our Lightspeed boundary across all the other dimensions we get what looks like a cone what scientists call your light cone so now we have a world line which is your entire life history at every point in space and every point in time and then your light cone which defines every single point in space-time where you could go or have been and light cones are what we are going to mess with to travel through time oh hey the easiest way to travel through time is to go forwards in time you and I are traveling forwards into the future right now at the blistering pace of one second every second if you want to travel into the future faster than this you either have to go really really really fast or you have to get near something really heavy wow it's good to have that back let's draw our diagram again and this time assume that we have two individuals one going really really fast and one just standing still as space-time progresses it's nice to have you back to buddy now the really really weird thing is is that even though this looks like more time is passing for the person who is going super super fast when you go that fast space-time squishes once space-time has squished due to her immense speed you can see that the time that has passed for Captain Marvel from spider-man's perspective is actually less than the amount of time that has passed for spider-man this is forwards time-travel because from Carroll's perspective she has aged less than the rest of the universe now we've never gone Captain Marvel fast to make significant forward time-travel a thing but we have gone fast enough to see forward time-travel effects over his over eight hundred days in space orbiting the Earth at many kilometers per second cosmonaut sergei krikalev has aged twenty two point six eight milliseconds less than all of us here on earth right now he is the record holder for time travel if you get very close to something extremely massive you can travel forwards in time to for example take the ultra massive and recently imaged m87 star black hole this is it projected through time because extremely large masses can warp space-time in weird ways your light cone will start to squish and tilt and tip over the closer you get to a black hole and so time will pass more slowly for you as if you are going altra fast and you can see right here at this exact distance from the black hole your light cone tips over so much that your world line the only possible path that it can take is into the black hole because otherwise you would be violating the light speed boundary and as far as we know humans cannot travel faster than the speed of light I know I said humans can't travel anyway this actually defines what is called the event horizon and this is why scientists say at this point not even light can escape so the closer you get to a black hole the less time passes for you relative to the rest of the universe and you travel forwards through time you look fantastic for like 70 traveling to the future is fine and very possible but it doesn't exactly help you address a certain snap and going back to the past is a whole different endgame I'm gonna say this right up front okay most scientists who spend their lives thinking about this kind of thing think backwards time travel is probably impossible there may be some weird hypothetical situations yeah not yet there may be some weird hypothetical situations or some kind of weird exotic matter that might make these situations more possible but these explanations themselves are extremely unlikely all of that being said though what if you can make a wormhole that seven at the speed of light let's say that Tony Stark anticipated the Battle of New York in 2012 he used billions and billions of stark bucks to somehow make a wormhole that connected two different points in space and time and whatever technology was holding those wormholes open could also move them through space-time at incredible speed now let's say that he constructed the wormhole in 2008 right after he became Iron Man as some kind of insurance policy he then spent the next few years accelerating one of these ends at near the speed of light because of the kind of forward time travel that we just talked about when this end stopped accelerating it would actually be younger than the rest of the universe maybe the rest of the universe is at 2019 now the really weird thing about wormholes is is that time is synchronous through them so if Iron Man and the rest of the Avengers now entered the wormhole had an age of 2012 they would emerge from the other end in the year 2012 right before the Battle of New York another suitably so I was gonna say that future me shut up another suitably superhero way to theoretically travel into the past is to construct and it's kind of fitting in 1974 scientist Frank Tipler proposed a solution to the general relativity equations that would allow for backwards time travel he theorized a giant rotating tube in space that was infinitely long in each direction the rotation of a tube like this is so incredibly taxing on the space-time around it that it would warp it in the same way that a black hole would light tones near it would start to tip over going back to our diagrams for a second you can see that if our light cone tips over enough the path your world line can take doesn't necessarily have to go forward in time it can go backwards if traveling through warped space-time like this can theoretically take you into the past then there is a path along a tippler cylinder with all these tipped over light cones where you can go around it and take yourself as far back into the past as you wanted going around past past past best maybe you'd maybe you'd get maybe get far enough back to like get the one that got away they danced now though there's a problem if there is a way to curve a world line so much that it comes back around through time and intersects with itself it forms what scientists call a closed timelike curve it is timelike because it is still within the Lightspeed boundary and events can be causally connected from A to B Thanos gets the Infinity Gauntlet and then he snaps the problem for the Avengers is is that even if you curve this line to travel back in time Thanos snapping is still on the world line it happens sometime in the past and therefore it has to happen Thanos is right in this regard he is inevitable this principle is known as the non akov self-consistency principle saying that whatever happens in this weirdness still has to agree with what happened at all other points on the world line this gets around the dreaded grandfather paradox which is good but it's bad for the Avengers because in this view of reality if this is the way you are traveling through time you cannot change the past period come on I just got him back if Avengers endgame didn't have a way around all these physics we'd have to conclude that the movie is fun but kind of logically impossible thankfully quantum mechanics comes to the rescue once again hey so you didn't do it but coward have you ever wondered if you could have done something differently in your past what would the world be like if you took a different path through space-time well one interpretation of quantum mechanics says that you did you did both you you did all of them every time you interact with the universe as a quantum system as you are at the smallest scales you split the universe each one unfolding with a different history this is physicist Huw Everett's many-worlds interpretation of quantum mechanics and it posits an infinitely branching tree of timelines every time quantum systems interact you as a quantum system have an infinite number of potential world lines but at our scale as a collection of particles we all really observe one path that we're going down but all of these paths have some version of you and your history traveling along it again this is all very theoretical but other scientists like most notably David Deutsch and Tony Stark named drops in Avengers endgame the Deutsch proposition think that if you could travel back in time from your world line and go back to the past because of quantum mechanics you wouldn't necessarily have to split off and then travel down some alternate history this gets around any potential paradoxes because you can mess with a past that is in your own you could even mess with yourself you could punch yourself in the face or get the hammer back from yourself still worthy yes this gets around time loops and paradoxes but more importantly if you were to somehow use quantum mechanics to jump back from your alternate timeline to what you perceived as your own original timeline you would be in fact in a future of your own making where you could change events in your perceived past even after punching yourself in the handsome face so now I think we are finally ready to address endgame all right sorry it gets even more fundamental than this many worlds approach as we went through in detail in our is ant-man secretly the strongest Avenger episode we experienced our own time as advancing from one point in space-time to the next our world line at least to us is a single line if we could figure out a way to travel backwards in time and we got there to an alternate timeline like the many-worlds interpretation suggests when we got back in time we would still experience our own world line in this way advancing from one point in time to the next when you go to quantum mechanical scales oh this solid line reveals itself to be something very different literally every single possible path through space-time this was one of legendary physicist Richard Feynman's many great insights that a quantum particle takes literally every single possible path through space-time and some of those paths are even yes going backwards in time but when we look at it from our human macro scale all we see is the single most likely world line we see the Grand Rope of time we do not see all the fibers that weave it together so in the quantum realm where the Avengers are supposed to go the path between two points in space-time doesn't look like this anymore it would look something like this between every two points in space-time there are an infinite number of quantum paths that would take you between those two points I've represented here as circles with decreasing density saying that traveling from one point in time to another like this like time travel wise would be very unlikely and the most likely line is the one that we experienced through space-time the straight line and of course there would be an infinite number of backwards paths through space-time for a quantum particle between two points in space-time as well my point is is that every single point in space and time is linked quantum mechanically at our scale you cannot see this infinitude of possible paths the collection of particles that we are we only experience the most likely path for those collection of particles a straight line through space-time however if you got down to the quantum scale you would experience you would see everything the key to all of this is that if you had ant-man's go quantum powers and Tony Stark's intelligence you might be able to pick any weird unlikely world line that you wanted to to take yourself to a very specific or many specific points in space-time say one knot of 14 million six hundred and five and I know this is all very very confusing and honestly I haven't wrapped my head around all this full yet I have spent for this episode 10 hours literally on a phone with a quantum physicist but keep all this in mind keep the analogies in mind and now it is time to address what actually happened in endgame okay so here's how the Avengers endgame timeline actually shapes up if they are truly following a quantum mechanical version of time travel I needed a lot of space so here is our Grand rope of MCU history a story starting canonically all the way back in the 1940s with Captain America the First Avenger and then progressing over 21 different films to the events of endgame were somewhere around 2023 the Avengers get time travel they go back in time they get the Infinity stones they'd come back the Hulk snaps and then Tony snaps and then people are dusted undusted and then Captain America comes back as an old man and makes you cry yeah this is too simple though for this film and for quantum mechanics so now let's see if we can unravel this rope to see what quantum fibers the Avengers took in terms of world lines to do what we see them do in the film okay so using the infinitude of possible quantum paths here's what the avengers actually do in 2017 when infinity war is supposed to take place there is a snap there's a five-year time jump and then there is time travel from that point they use the powers of the quantum to take these unlikely world lines back to 2012 2013 and 2014 from there they each have their separate missions to grab the different stones eventually all returning back to this point will cap and Tony travel back to the 1970s to grab the tesseract after it falls on their hands and into Loki's hands oh I wonder what happened with him we don't know and then they also grab more Pym particles they also jump back in the same amount of time a brief amount of time later Thanos an alternate version of Thanos and an alternate version of Gamora and nebula both jump back to this original world line from there on Hulk snaps and then Tony snaps in the movie is more or less over until Captain America returns all the stones first to 2014 and this is just my interpretation because it would look pretty and make more sense first to 2014 than jumping back to 2013 2012 1970 returned the tesseract and then to the 1940s to take an unlikely alternate world line with the power of the quantum to live out a full life with Peggy where things mayor not have happened in the MCU were not really sure and then he returns as old Captain America this is a lot so you might want to pause the video to get a handle on it and remember these are only the various paths the Avengers chose to take using the power of the quantum in reality there are literally an infinite number of paths to and from each point on this Grand rope of MCU history from 2012 to 2023 for example and from 1940 to 1945 seconds and back again and remember this is just my quantum mechanical interpretation of what's going on the timeline of events in some Marvel production office might look very different however this approach does theoretically get around all of the closed timelike curve and potential paradox problems I applaud the movie for bringing in quantum mechanics and acknowledging the problem with closed timelike curves if this was just a single timeline for example there would be a lot of problems like future nebula shooting herself from the past that would be Back to the Future stuff and you know what the Hulk thinks about that quantum mechanics is really the only way that this works because if you could get to the smallest smallest scales of the universe where an infinite number of branching paths through every point in space-time were open to you you could metaphorically choose-your-own-adventure you could pick the one out of 14 million 605 world lines and live it as your own history and change your future and from our perspective our non quantum perspective observing all this happened it would all be the same story the same engine so there you have it 10 years of the MCU culminates in a surprising way with the quantum physics of time-travel of all things and much of the movie works theoretically if you give it the biggest possible benefit of the doubt which I think we can do there's inherent tension in any sci-fi story and especially in time-travel stories between the narrative that you're trying to tell and the science that you're trying to get right and some time's one features more than the other and that's fine endgame was very satisfying for me and in all seriousness the MCU has been helping me learn and teach and excite for my entire career so thank you Marvel your movie was pretty dang cool so here's to another ten years of and because science hmmm I wonder if there's any footage I could show of any kind of science show that maybe I don't know a year ago predicted the exact mechanism of how Avengers endgame would happen with the exact right characters could we find any footage like that this is potentially a way to save half of the universe mm-hmm validated you live life in the past it's weird I know but wrong timeline thank you so much for watching Jonathan and a big thank you to dr. Spiros Mitchell aqus at the Institute for quantum information and matter a good friend of mine who actually advised on films like ant-man and spider-man and Captain Marvel he talked with me for hours about how to make this kind of time-travel work so thank you so much my friend I hope I didn't bother you too much also we have the full series of the science of mortal kombat now live please go watch all six main episodes we worked really hard on them and I'm glad that many of you are enjoying them I very much hope to do something like that again for you all very soon if you want to follow us on social media you can do so right here to give us ideas for future episodes and thanks


Because Science · May 14, 2019 at 8:43 am

Thanks for watching Super Nerds! This was by far the hardest I’ve ever had to think about a script, literally hours on the phone with a quantum physicist, but I’m happy with the result. I think we understand the timeline more than the writers or Russos do now! See you in Footnotes. — kH

Caboose The Michael J Caboose · May 14, 2019 at 8:43 am

I can't tell you how many times my mind broke during this video.

Edward Love II · May 14, 2019 at 8:43 am

Could you explain how Thanos's double edge sword was able to break Cap's shield?

Bryson F · May 14, 2019 at 8:43 am

Someone tell me how captain america gets old with regenerative cells so potent he cant even get drunk???

AnInsomniacsNightmar · May 14, 2019 at 8:43 am

My hardest time with multiverse theory is all known and all unknown universes are created and undone at your coin flips. Feels a lot like the simplistic science of flat earth with the universe revolving around us. Since if the universe did revolve around us I would be strongly suspecting that my brain was in a vat. The hubris that is man.

froggy1600 · May 14, 2019 at 8:43 am

When did Thor lose weight, grow his hair back, and lost his manly voice?

Grantonator · May 14, 2019 at 8:43 am

Tony mentions the Mobius strip (bagel) when plotting a course through time in the quantum realm, I was wondering how that shape related to how the avengers traveled, or if it was just something to do with programming. Also, old cap doesn't return through the portal. Which means he did something different.

Isaac Kotlicky · May 14, 2019 at 8:43 am

PEGGY! … they danced.

Martin Roberts · May 14, 2019 at 8:43 am

Did it not bother anyone else that cap was back in their world at the end? All the time travel stuff was done based on the multiple worlds theory right? So he went somewhere/ somewhen to be with his girl. Okay so even if he lived out his life there with her and grew to the ripe old age as shown it wouldn't be in the same world as everyone else and so there's no way he'd be sitting on that bench. I can't be the only one this is driving crazy!

Aimee Beaupre · May 14, 2019 at 8:43 am

makin' science sexy..

Vaeldarg · May 14, 2019 at 8:43 am

Fresh from seeing Endgame, time travel in the movie is separated into what is explained in the movie as what is happening, and the meta-explanation in which the Many Worlds Theory is used as Hollywood's favorite cop out to avoid maintaining logical consistency when involving time travel. Naturally, please expect there to be spoilers within the comments section of a video full of spoilers.

Using the cop out, any situation that would seem to produce a paradox can be explained by the characters actually bouncing between two realities: the one in which Dr. Strange gives Thanos the time stone, and the one in which ol' Hulk Bannon meets the mystic and is given the time stone. This pairing of realities was what was necessary to produce Thanos's defeat. For example, Present Nebula was only able to kill Past Nebula when Past Nebula jumped into the reality of Present Nebula. Past Nebula is no longer present in her original reality.

As Hulk Bannon kind of explains before they jump to the other reality (what they think is their reality's past), time is a series of causes and effects that forever exist as observations. You cannot change an effect by changing the cause, because you would then have had no reason to go back in time to do so. Time would have already been changed the moment you had the intention to change it.

Yoel Merino Quintero · May 14, 2019 at 8:43 am

idea for a video, how powerful is the dragon breath from game of thrones biggest and baddest dragon?

Andy Welch · May 14, 2019 at 8:43 am

pushes Incredible Hulk aside but leaves Thor 2 where it is
… Do you even Marvel, bro? 🤣

Zach Detour · May 14, 2019 at 8:43 am

And Stan lee was just writing comics

infinitekurosoul · May 14, 2019 at 8:43 am

still doesn't explain how Cap got back into the original timeline without using the time machine

Greg A · May 14, 2019 at 8:43 am

Love this guy. The YouTube Brian Greene.

Zeugirdor · May 14, 2019 at 8:43 am

I just want to know who the fuck dislikes these videos

Dillian Criker · May 14, 2019 at 8:43 am

I loved this

Jonathan Thörn · May 14, 2019 at 8:43 am

You're welcome my dude!

Caz Master · May 14, 2019 at 8:43 am

Best explanation I have found thanks!!

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