Parallel Worlds Probably Exist. Here’s Why
The most elegant interpretation of quantum mechanics is the universe is constantly splitting
A portion of this video was sponsored by Norton. Get up to 60% off the first year (annually billed) here: or use promo code VERITASIUM

Special thanks to:
Prof. Sean Carroll
His book, a major source for this video is 'Something Deeply Hidden: Quantum Worlds and The Emergence of Spacetime'

Code for solving the Schrödinger equation by Jonny Hyman available here:

I learned quantum mechanics the traditional 'Copenhagen Interpretation' way. We can use the Schrödinger equation to solve for and evolve wave functions. Then we invoke wave-particle duality, in essence things we detect as particles can behave as waves when they aren't interacting with anything. But when there is a measurement, the wave function collapses leaving us with a definite particle detection. If we repeat the experiment many times, we find the statistics of these results mirror the amplitude of the wave function squared. Hence the Born rule came into being, saying the wave function should be interpreted statistically, that our universe at the most fundamental scale is probabilistic rather than deterministic. This did not sit well with scientists like Einstein and Schrödinger who believed there must be more going on, perhaps 'hidden variables'.

In the 1950's Hugh Everett proposed the Many Worlds interpretation of quantum mechanics. It is so logical in hindsight but with a bias towards the classical world, experiments and measurements to guide their thinking, it's understandable why the founders of quantum theory didn't come up with it. Rather than proposing different dynamics for measurement, Everett suggests that measurement is something that happens naturally in the course of quantum particles interacting with each other. The conclusion is inescapable. There is nothing special about measurement, it is just the observer becoming entangled with a wave function in a superposition. Since one observer can experience only their own branch, it appears as if the other possibilities have disappeared but in reality there is no reason why they could not still exist and just fail to interact with the other branches. This is caused by environmental decoherence.

Schrodinger's cat animation by Iván Tello
Wave functions, double slit and entanglement animation by Jonny Hyman
Filming of opening sequence by Casey Rentz

Special thanks to Mithuna Y, Raquel Nuno and Dianna Cowern for feedback on the script

Music from "Experimental 1" "Serene Story 2" "Seaweed" "Colorful Animation 4"

  • SuperRobotFish

    because of the butterfly effect, is there a version of earth where the dinosaurs are still alive right now?

  • Mads Sørsdal
    Mads Sørsdal

    I am hungry now...

  • lastdaysguitar

    0:00 What's all this, or Norton 360 have to do with the gassed cat?

  • Mike Finn
    Mike Finn

    Infinitely variable is not the same as deterministic.

  • john almers
    john almers

    The special punishment acutely mine because july meteorologically arrive round a callous swedish. learned, handy stitch

  • j

    if its true.... maybe santa is true too?

  • Bendilin


  • ican dae
    ican dae

    Hitler would end up an artist

  • PDP777

    But if theres an infinite version of me and the versions are different and have different characteristics can I still say that those versions are in did a version of me???

    • Vladislav

      It's almost like your version of you tomorrow. Or 10 years from now. Or just you as today - compared to what you thought of would be you today like 10 years ago. You here and now is the only you, is what I'm saying)

  • Frederick Lynch
    Frederick Lynch

    Which means that Prof.. Carroll is a version of the President Carrol, in President Carrol's universe - who is the "real" Sean Carrol? There is no "real", and no original.

  • He Ka
    He Ka

    Occam's razor anyone?

  • Truthismyfriend

    No, it's just a gimmick to confuse people, weaken character, deny a creator, and sell books. Time travel meets String theory and Reincarnation, or, Mental Masturbation.

  • Ric F
    Ric F

    Yes I get it, and I don't, or I might, and I could, but I won't, or I should, and anything besides, and all things as well.

  • Just Neoh
    Just Neoh

    Erwin Schrodinger, as the discoverer of Schrodinger Equation, was in a superposition of loving and hating his equation. In another universe, Einstein was the one proposing psi square as probability density of wavefunction, whereas Max Born and Niels Bohr said God does not play dice.

  • David Terr
    David Terr

    I don't know if it's reassuring or disheartening that in the multiverse, our other selves are doing everything we might have otherwise done in this one, such as becoming president or a mass murderer.

  • Rod Snyder
    Rod Snyder

    this was an awesome episode! also Prof. Carroll, I like that shirt u wear a lot! Very nice explanation to that topic. Thanks

  • HauIchDich

    I got it but Dude, I wished I could used this for any tinder date….

  • Randall

    No they do NOT.. is called bad math.. it is bad math when you have to make up things to make a theory work. They only exist in theoretical math.. Just like neutron stars do not exist, they a theoretical and none has ever been found, it just an idea. When we drop the BS in science only then will we move forward.

  • hi

    somewhere out there I'm dating my fictional crush

  • inv isible
    inv isible

    I really believe that we have parallel selves living on a different dimension. I start believing that it is not impossible to happen because I wonder why people dream, why do we experience deja vu and since deja vu is linked to a parallel universe. It could be that our dreams are the exact moments that are happening on the other/parallel world. It’s like we are seeing a vision of us through a dream. It’s interesting but at the same time it’s a little bit strange to me.

  • Dark Cheese
    Dark Cheese

    where does all the energy to make more universes come from though?

  • Neutral Warlord 2
    Neutral Warlord 2

    Somewhere in a parallel universe, there's a stable version of me

  • French Flacco tv
    French Flacco tv

    Why does it have to be a bunch of different universes? One where you’re president? Why can’t it just be universes multiplying slower than me and faster than me? That would make me believe time travel exists rather than going to a different world with slight changes..

  • MetOshi

    If opening the box creates 2 different quantum states, then setting up the experiment and closing the box in the first place does the same thing. Everything becomes entangled from the start, cascading throughout time and space, past, present and future. Solving these mysteries will take time but boy oh boy would it be real interesting to see how it progresses

    • Vladislav

      But remember that there must be partcles that will carry information about change in states (like photons bounced off cat awake, or asleep) - that's what makes it real, not our calculations beforehand.

  • Raymond Carty
    Raymond Carty

    I have a question. Is the spin of an electron actually up and down before it’s measured or is it that we can think of it like that. I’ve heard many people say different things in videos.

    • Vladislav

      There's a device called interferometer (after a phenomenon of interference). Long story short, this device (like many-many others, including double slit experiment; and even single slit!) would have given totally different results, weren't electron truly in all possible states at once! Prior to measurement.

  • Kevin Akers
    Kevin Akers

    I usually get further into these videos before I’m completely confused. I only made it 5 min this time .

  • Lalit Sharma
    Lalit Sharma

    So out of all the infinitely many possible worlds why did we get stuck with the worst one?

  • BitDuelist

    Man, the TVA must have their hands full

  • Arik Iczkowski
    Arik Iczkowski

    In an infinite universe, there is a me that is KING OF THE WORLD!!! KNEEL BEFORE ZOD, PEASANTS!!!!

  • Jack Leahy
    Jack Leahy

    Does the effect of Schrodingers cat apply into 3/4 simitainoisly? As one could argue that either outcome happens on either side of the universe as the opposite reaction. Using the super position to throw one of these atoms on either side, one side it decays the other it doesn't. Meaning that instead of branching into two universes we have only one singular universe, with its somewhat opposite playing out just passed the big bang. Would be a little more difficult then that to find based on the curvature of space. This is just me trying to understand an extremely complex idea while skipping over the years of math and science study's to learn all the math surrounding it. But at the end of the day it sounds like a tree in the forest with no one to hear it.

  • Ken Burroughs
    Ken Burroughs

    "At that moment you are split" there is no parallel universe for people who DON'T put cats in boxes, and a parallel universe for all those who do ! And the more cats you put in boxes, the more parallel universes you create, because "at that moment you are split"

  • S D
    S D

    I am happy that there's a version of me married to the hottest woman on earth. Not sure if that version is happy though.

  • Dank Memes
    Dank Memes

    So there is a world where she loves me?!😔🙂

    • Dark Cheese
      Dark Cheese


  • Barney Stinston
    Barney Stinston

    The violent sardine intrinsically tap because brick daily flood unlike a rustic sex. inconclusive, common low

  • Hitesh Ganga
    Hitesh Ganga

    complex science

  • Astro Soul
    Astro Soul

    Now, explain immortality. We could just never die, since there are so many different realities in which you don’t die

    • yems

      You may die, but a parallel version of you may not but yes you are correct

  • Cluesman

    so derek, what kind of video would you have made if you were on the branch that didnt come up with the parallel worlds theory?

  • Jayderic johnpresti
    Jayderic johnpresti

    man this is how I imagine quantum physics whenever I am in a profound mood and on the note of many worlds means everything happens, I like to call those subdivisions of the "timeline(s)" choices and some choices like proton turns into electron are inaccessible because you would have to change the rules that this world runs on and we don't necessarily know these rules because, well think of it this way, you can't see the mountain when you are at the top we could theoretically see the rules of other universes and their timeline(s) [subdivisions] but we can't see our own rules beyond what we already see. sorry for the rant I don't get to do this with my brothers they get bored and bouncing it off myself can get boring because of the existential knowledge that I might not get to explain this to someone else without them getting bored.

  • WWeronko

    Complete crap. I suspect God made the universe non-deterministic to make it interesting.

  • Memetics

    The major problem with people's understanding of these concepts is the notion that "measurement" to them means "a person choosing to measure something and becoming aware of the result." Measurement in the quantum physics sense has nothing to do with humans or consciousness. It is all about the interactions happening between the measuring device or system and the thing being measured. When you bounce photons or electrons off of something in order to observe it, you change both things - not just the light or electrons returning to the measuring device but the thing they bump into. It makes so much more sense of quantum mechanics to just think of the whole universe as one wave function - one that we awkwardly try to understand small pieces of from our limited, flawed, incomplete perspective.

    • Jerry Mitchell
      Jerry Mitchell

      But the only way to test that hypothesis is to conduct an experiment where no one ever does choose to conduct it or become aware of the results, and that experiment is already running all the time everywhere. "Our perspective" includes all of the capabilities of science, and science can't look outside its own capabilities, by definition. (Because science is only science in conscious minds.. to a jellyfish it's.. well, I don't know what, because I don't think a jellyfish even has "sounds" or "shapes".. something less than that.)

  • Jose Medina
    Jose Medina

    The spiffy vessel methodically invent because eggplant assembly appreciate but a untidy metal. abiding, discreet shape

  • Ibian666

    Any claim without evidence can be dismissed without evidence. So, no.

    • Ibian666

      No, it has sophistry and a complete lack of practical experiments.

    • Rowan Weathersby
      Rowan Weathersby

      This actually has evidence backing it up, he explains it in his video, the problem comes when determining which explanation makes more sense, as they both would make the same set of predictions, meaning the many worlds interpretation is untestable against other interpretations. TLDR: it has evidence for it's existence, but it's the same evidence the other interpretations use.

  • †XΞZIAN†

    reality is in a super position, but instead of 2 states, it's infinite

  • Jerric Aliermo
    Jerric Aliermo

    Not sure if this has been asked but I'm curious if the branching of worlds can be observed in the same manner as that of a logistics map from the other video you posted?

  • Jason Bramble
    Jason Bramble

    So does this mean that we are functionally immortal? Because there is always a probability we could survive any event we encounter. We also would only be able to observe surviving if we were alive in that divergent universe. So would this suggest, that from our POV we couldn't die... but rather each of us is doomed to immortality and watching others die around us?

    • Rowan Weathersby
      Rowan Weathersby

      This is what we experience in real life. You will live forever from your point of view, because once you die you can no longer observe your non-existence. You can observe others people's non-existence when you are alive.

  • Phillip Price
    Phillip Price

    The attractive wrinkle cytochemically wail because bedroom orally stop behind a peaceful tabletop. nifty, plant dungeon

  • hardino0311

    I would say.. humans still don’t have a clue what the hell is going on

  • Michal Wasilewski
    Michal Wasilewski

    I'm in a state of understanding and not understanding this video at the same time.

  • YoZeusChill

    I’ve been thinking lately, how come we live in such a big universe and we’re the only ones that live in it? I’ve always felt like there’s other life out there in the universe or atleast a multiverse

    • Rowan Weathersby
      Rowan Weathersby

      This is called the Fermi paradox, we should see more life forms and alien civilizations than we do (0), but we don't. This could be due to a "filter" of sorts, where species die out before we have the ability to detect them. The question is: is the filter ahead of us, ie. Climate change, or behind us ie. Abiogenesis?

  • bill wi the science fi
    bill wi the science fi

    Somewhere theres a version where im still with her

  • 秀麗

    Great content

  • Sayan Debnath
    Sayan Debnath

    11:13 so you mean there are infinite numbers of parallel universes and the number still growing exponentially.. Never think of this. edit :- I should wait before commenting.

  • William McCartney
    William McCartney

    Does the quantum entanglement also lends itself to the hypothesis of instantaneous speed of light transmission on the receiving end. Now the information once being observed i.e measure instantaneously transmits it's information back to entangled particle.

  • Emil Barnabas
    Emil Barnabas

    The copy of me in the other universe has seen the whole video.

  • Jonathan Jollimore
    Jonathan Jollimore

    Went Pythagoras made observations that made him believe the world was a round shape he couldn't see it and couldn't prove it just use his logic and reason to observer and make educated guess. Just because something can't be immediately proven doesn't mean you should ignore your logic.

  • Efry Alfyyansyah
    Efry Alfyyansyah

    Alam Ghaib...

  • Justin Magana
    Justin Magana

    So quantum mechanics is just theoretical probability that has nothing to do with anything that true and set in reality?

  • Prateek

    Imagine the world which formed during the big Bang theory where no big bang theory took place!

  • Epic Patato
    Epic Patato

    the thought terrifies me.... minecraft doesent exist

  • Harts Knot
    Harts Knot

    I wouldn’t be surprised if someday we find out that the universe is infinitely big or ever expanding in all dimensions, not just in distance or time. Maybe all we are is some sort of energy that simply exists, and everything that happens(including its existence) can be described as entropy. That way it makes sense how the Big Bang happened without anything “prior”, since we all are just waves of energy and it simply transcends states infinitely. So maybe everything is infinite in infinite ways that it could be infinite(like the multiverse theory). Then perhaps physics could be treated as math

  • urchin getter
    urchin getter

    It's called save player 1

  • Sergiovsousa

    I found it rather disturbing there´s a even more miserable me somewhere else...

  • Charly Her
    Charly Her

    This video is a fail. For example, SQUARE ROOT of 100 can be 10 or -10. If you take the square of 10 or -10, it would b e 100. However, having two possibilities DOES NOT mean that there are two realities, but two possible realities. This means, if the A (the answer) is not at 10, then it must be at -10. This means if I slingshot a bird at 10. If no bird was hit, then the bird is at -10. And thus, if you slingshot at -10 then you would hit the bird. The bird is only in one reality either at -10 or 10 but not both. In conclusion, there are possible realities but there is only one real reality such as the bird example.

  • Hasan Imam
    Hasan Imam

    4:55 Says "there is a better way to think about Schrodinger's cat" Me: lets hit the like button first

  • Matthew

    The Universe is either cyclic or just manifests from "nothing". The branches of probability can express themselves organically with every new instancing of a Universe so therein lies the potential for our own existences to be reiterated upon throughout the course of eternity.

  • corrupted Ninja 2
    corrupted Ninja 2

    Somewhere out there there is a me that does not simp for anime girls


    Scientists try to Explain Isekai

  • Tung Hansen
    Tung Hansen


  • AnonymousWombat

    The more I watched, the more contradictions I saw. This theory doesn't make sense. I'm gonna research more.

  • Jay Lloyd
    Jay Lloyd

    I think I'd prefer not to know about this!

  • fusion

    So, what decides me being present(consciously) in a particular reality and not in other ?

    • Jerry Mitchell
      Jerry Mitchell

      Nothing. You're in whichever one you think you're in, because every atom in your brain has already been entangled with some small subset of different realities in which "you" became real, and every time you have a new thought, you've entangled your "self" more, just as you're now entangled into only the subset of universes where you asked that question. "You" is ultimately just a single path through that space, and you're "in the universe" of the path that lines up with.

  • ディオゲネスDiógenes

    In another universe Latin America's countries are superpowers

  • Rubix Potato
    Rubix Potato

    Everyone makes the joke that "in a parellel world x is true" but if the number of worlds is near infinite then every world also appears multiple times, if not an infinite number of times. There's not a single world in which you're president, there's near infinite of them. Even so, this is the only world in which I'm this swagger 😎

    • Rowan Weathersby
      Rowan Weathersby

      Good point, there's either an infinite number of worlds with any possibility, or zero.

  • Bakalu supreme gaming
    Bakalu supreme gaming

    I have a question does every single word I say create parallel world because of how many words I say out of all the words

  • vinh hoàng
    vinh hoàng

    This man is 1 of the TVA i guarantee

  • Adam Kovar
    Adam Kovar

    When exactly does the wave collapse? The moment the box stops being a vacuum, when my eyes hit it, or is it once I decide to open it? Wait if I opened it the moment I decided to open it consciously, I would’ve already decided. Does it collapse the moment I unconsciously begin the process that will result in me opening it?

  • Fresh Sans
    Fresh Sans

    I'm blaming my ADD for me being awake watching this

  • Jarie Suicune (Jarie スイクン)
    Jarie Suicune (Jarie スイクン)

    Why does Schrodinger's cat get excluded as an observer? It is observing itself the entire time, not just the humans outside. Furthermore, what if an entity could see through walls? (say, Q, from Star Trek.)

    • Vladislav

      You're right: from the point of MWI, these equations with superpositions in them are suitable only for particular kinds of observers - ones that are not able to see beyond the walls (i.e., didn't catch a photon bounced off a cat yet), or ones that are still wait to catch it. And once they did, they will branch\decohere.

  • guy sumpthin
    guy sumpthin

    A video for stoners , all speculation

  • Jarie Suicune (Jarie スイクン)
    Jarie Suicune (Jarie スイクン)

    How does split universe balance with conservation of energy? If there is, then there is spontaneous creation of an entire universe of energy. Also if you could detect it at all, would that not imply the transfer of energy between those universes (the ultimate source of energy, just drain another universe)?

  • David Terr
    David Terr

    Pretty wild idea that the only really fundamental thing in nature is the multiverse and that our universe is just a convenient fiction we create for ourselves.

    • Jerry Mitchell
      Jerry Mitchell

      Even wilder if you consider our "selves" as just a convenient fiction the multiverse creates.

  • MrHighway

    I don’t think multiverses exist. I think it has something to do with time. In the cat thought experiment you can view the alive cat as a cat that hasn’t died yet. Two states separated by time. Idk. a voice in my head told me to type this on here. Whoever was meant to read it....Godspeed.

  • MrHighway

    Ooooh so jada pinkett and august alsina were talking about two intrinsically linked electrons colliding towards each other. Now it all makes sense

  • Travis Grubb
    Travis Grubb

    I once thought of a fictional concept where human "souls" are able to sift through the multiverse to avoid death. It involves the many worlds theory but adds a little mysticism. The idea is that just as soon as you die, your "soul" leaves that reality to find another reality where you survived instead. It all happens in an instant and is impossible to perceive. After watching this, that concept came right back to mind and makes more sense now. Think of the cat in the box, to us it's either dead or alive but to the cat, it's always alive. It's as if the cat's "soul" has no other choice but to go down the path where it survives. Just imagine that... food for thought.

  • Jesus

    Can you please show me what my wires look like in all the other parallel universes?

  • brendan smith
    brendan smith

    i like watching this videos when im procrastinating on my work so i can justify it by saying im learning

  • Jos Jaison
    Jos Jaison

    Jada Pinkett Smith🤣🤣🤣

  • Hephaestus

    Good ol multiverse theory, makes for a good story beat.

  • Jimmy Hillgren
    Jimmy Hillgren

    This is just my theory. In each world set there is as many parallel worlds as there is of the smallest part or building stone which I call a Plumin. That is for a world of one building stone there is up to four worlds one for each state it can be in. And this goes all the way up to the critical mass where it simply collapse in on itself over and over in an endless big bang - suck up loop without any world progress. A world set like the one we live in could be in the trillion billion worlds scale. You could be an alien or an elephant right now in a parallel world.

  • Valy

    So let's recap, was Back to the Future inspired by true events?

  • TheLazyWanderer

    ... k I'll get the bananas and the microwave. And my phone.

  • SirDuvalin

    In another parallel galaxy I am probably attractive with a gf

  • Jeff Bezos
    Jeff Bezos

    The observable universe operates at a specific clock cycle speed. Multiple universes can exist in between each clock cycle that you as a person observes (and exist within). Each clock cycle computes the energy transfer motion across the universe for that frequency. Conway's game of life can be computed in an infinite number of interlaced "universes" only throttled by compute power.

  • Jeff Bezos
    Jeff Bezos

    It is infantile to think that if you aren't observing something, it doesn't exist ... or exists differently.

  • FreeLookMode

    Frankly, I've always found this interpretation far less nonsensical than the Copenhagen interpretation. I'm mean, define "measurement"

  • dadautube

    everything good in this video BUT for the in-video commercial ad in the end!

  • Global and historical thoughts
    Global and historical thoughts

    In a parallel universe, Epstein still didn’t himself.

    • frostonium

      yes, Epstein still didn't himself

  • autotactic

    So, the whole quantum mechanic problem is just because our measure stick is a little too big? Nobody working in math 2.0?

    • Vladislav

      There're videos on SVsoft where you can see double slit experiment producing interference pattern with slits about a 10th of a millimeter wide. And that's just a one example when quantum effects can bee seen on our everyday scale (like millimeters and so forth) - on smaller scales they're just wilder. But the math is the same everywhere, and it's the most successful theory in history, exactly in terms of it's predictive power in experiments.