Parallel Worlds Probably Exist. Here’s Why

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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: bit.ly/32SM0yd or use promo code VERITASIUM

Special thanks to:
Prof. Sean Carroll www.preposterousuniverse.com
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: github.com/jonnyhyman/Quantum...

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 epidemicsound.com "Experimental 1" "Serene Story 2" "Seaweed" "Colorful Animation 4"









コメント数 46 648
Ron Villejo
Ron Villejo 4 時間 前
We often seem to frame Schrödinger's Cat as a dichotomy: as both dead and alive inside the box, then, upon measurement, dead or alive. But if the cat is truly in a state of superposition, i.e. in many, if not infinite, states at the same time, then when we open the box and check on ("measure") the cat, that cat can be in any state of 'aliveness' or 'deadness.' e.g. The poison may have just been released, the very moment we open the box, and while the cat may have inhaled a portion of the gas, it wasn't enough to kill it. However, perhaps that portion was enough to injure the cat's lungs, or something, so while it didn't die, its health was severely affected.
I love you Veritasium
Maayan Sacks
Maayan Sacks 8 時間 前
Litterely so creepy
Jafar Vlogs
Jafar Vlogs 9 時間 前
That is SO confusing
Neil Libertine
Neil Libertine 9 時間 前
There are many ways to prove that time dilation and length contraction are not actual but apparent, here is another try. Suppose an event happened in rest frame and two relative observers with different relative speed to rest measured two different value of time interval of event, also different from at rest. Relativists says that all time measured in three frames are correct as per their frame. So time appear different for different speed and they all are correct having different value. Okay, but that is measured from their frame of an event in another frame and an event is independent of relative measurement. Thus boosting time is not measurement of time in own frame but due to relative motion about other frame, so speed of frame not affect time in own frame. If relative time dilation is actual then what is value of time dilation when observed by more than one relative observer as in above example. So how could motion alter slowing of age, lifetime of particle and all that nonsense.
Nicholas Ackerman
Nicholas Ackerman 19 時間 前
I know I’m kind of stuck on everything in the universe is shrinking and but what if dark matter and energy is the spreading out of infinity into the multiverse and that there is no loss of matter or energy just the infinite division of our universe caused by primordial black holes that make up the smallest particles and as they collapse they empty out into primordial white holes that divide us into the multiverse and give us the effect of change that we perceive as time, gravity and the expansion of the universe? So an accumulation of primordial black holes could slow down time and then singularities would seem very large like the black holes we can see?hummmm?
Michael Grubaugh
Michael Grubaugh 20 時間 前
The expert on the subject is a goofball. What a bunch of rubbish. I love it.
jpeg 20 時間 前
With this theory that means there's a universe where parallel universes don't exist
James Rohal
James Rohal 22 時間 前
"Every outcome happens 100% of the time" except the leafs winning the cup
Thomas Jamison
Well, thank goodness Schrodinger didn't put a Jewish person in the box. That was for someone else to do in those days...... But the relationship of math to the physical universe is not absolute. Math is wonderful, but it shouldn't be confused with the actual universe however useful it is in certain cases.
Lynn Handley
Lynn Handley 日 前
Excellent clear description of the many worlds theory. This is a great video but the camera work at the end with Prof. Carroll made me nauseous.
Kaiser Soze
Kaiser Soze 日 前
I can do whatever heinous or evil act I ever desire To, since there must be some equally valid version of me that didn’t do those (we arnt special, and nothing matters, since every possible action I take, there is another me who didn’t do them)
Ritvars Rolis
Parallel world probably exsists.Thank you!🙏
Aman Hafeez
Aman Hafeez 日 前
My boy Sean!!!
Kevin Prouten
So how many dead cats will I need to get the British government to return the land it stole from my wife's family
When considering many worlds a universe and a multiverse he answer is there are infinite 2 one and none. All matter and anti matter meets in the past with the big bang. As does all anti matter being a positive and negative universe one going forward in time and the other going backward in anti time. each time the universe the a splits here it does in the anti universe and that is where you get the conservation of energy.
Mathtron 5000
"But first, we need to talk about PARALLEL UNIVERSES"
Soul Mechanics
Your guy is wrong though.
Soul Mechanics
"Every outcome has 100% probability every time." You said it. You are correct. There is only one of those. Nothing is contributing any lesser. It is not possible.
Soul Mechanics
You just got around to catching this? Please don't tell me somebody else had to tell you..
Soul Mechanics
Almost immediately? No no.. it happened. Faster than immediacy.
Soul Mechanics
fun facts
fun facts 日 前
That cat experiment was just an example to prove his point
Yes, parallel universes exist 🥰
OctaBech 日 前
It's all bollocks and I can prove it - if there were to be infinitly any dimensions, there would have to be one where I understood everything said in this video.
Carlos Landaverry
Bro your couch has a black stain, it's driving me crazy man
Colleen Forrest
It could be the opposite though. No branches, just the wave and we exist in all possibilities at all time, but when we take a look we only see a random point along the wave and that becomes our reality. Someone else might look an instant later and see a slightly different point of the wave and that becomes their reality. Now both you and the other person have slightly different views of "what happened". Which one of you is correct? The answer is both. It's just like the blind men describing an elephant. Maybe this is why people describe events of a crime scene slightly differently to police. Maybe they aren't remembering things incorrectly, maybe they are accurately describing the part of the wave they saw.
Samiullah k
Samiullah k 2 日 前
branching happens only once a year, your probable pathway to judgment day changes, enjoy. you dont exist in a parellel multiverse but its a multiverse of time, we can only dream of matching the prophets what had got😆😂😁👍
Mehmet İkbal Korkmaz
We're stuck in one of the parallel universes where all the outcomes of the quantum interactions led us to discover the Murphy's law.
Lol i understood the whole thing, starting from shrodinger function till the end
UnspokenSelf #Team Seas
I'm glad that there's a parallel universe where I have a worse life. Be grateful kiddos
Nikita Cebotari
Nikita Cebotari 2 日 前
Im not qualified to clearly state whether this is correct or not, but I can't understand this: If the entirety of all can be described by 1 wave function of everything, does that mean that everything is already entangled and there is no branching?
Szusza Webster
Szusza Webster 2 日 前
I was hoping you'd say, "I want to show that there is a better way to think about Schroedinger's Cat. In fact, a better way to think about..." (cats in general). Needless to say, I'm a cat enthusiast. I mean, why couldn't it have been a snake, or a rat, or anything other than the most popular pet??? Anyway, I've thought a lot about the infinite possibilities and multiverse theories and for some reason my first reaction to this solution is, it's a "cheat". I guess it was clarified in the end by calling it a "convenience". Perhaps I'm wrong, but perhaps I'm right, and perhaps, I'm both. :)
Brian O'Shea
Brian O'Shea 2 日 前
Yeah that didn't clear it up for me at all. 🤪
danny D
danny D 2 日 前
In conclusion: we have no clue of what's going on.
CeeJay C
CeeJay C 2 日 前
I don't buy it. The wave function is just a way to understand the phenomena of measuring quantum behaviour, it is not a rule book for it.
Thisriceiswhite 3 日 前
I felt good stuffing my brain about this. thanks
Thisriceiswhite 3 日 前
the fact that i felt like i basically understood everything of what they said in that interview in the end made me feel that simultaneously, I do not understand anything at all. or maybe i do idk
Virgílio Vilela
The term 'entanglement" to me was used with two different meanings, one subatomic and the other one macroscopic. How one entangled particle can result in solid bodies of matter be replicated?
Jozsef al
Jozsef al 3 日 前
that man is just sad cuz he lost to a game a chance and he likes to think that he won in another universe
Guilherme Jurdi
Guilherme Jurdi 3 日 前
For me (only a surgeon with a little curiosity about physics) that’s a clue that our understanding of atoms, electrons, etc. are still very inaccurate even though many of the mathematical descriptions can resolve many of the problems we have.
doctor strange
doctor strange 3 日 前
Me: clicking the video but don't understand anything but it was interesting probably + I am 13
DOSRetroGamer 3 日 前
But the cat is an observer. It knows if it's alive so it also 'knows' the state of the atom
Ante Bagaric
Ante Bagaric 3 日 前
Copenhagen interpretation is bogus, that much I agree. But Everett interpretation is no better. It's sheer fantasy, which arises from mathematical formulas. And it APPEARS to be purely subjective. For example, TO ME, de Broglie-Bohm interpretation makes much more sense, even though it 'violates' the idea that information can't travel faster than the light. Breaking the supposed 'law' that 'nothing moves faster than light' seems much less of a conjecture, than positing the ridiculous idea of 'infinite parallel universes' just to satisfy some mathematical formula. So, I would rename the title of the video 'information PROBABLY CAN move faster than light'. That is the equivalent title, just taking de Broglie-Bohm interpretation as 'more likely' than Everett. I don't think you can even measure which one of those interpretations is 'more likely'. As I said, it appears to be somewhat of an acquired taste. Some people prefer believing there are 'infinite number of parallel worlds', but I prefer believing information CAN travel faster than light (since de Broglie-Bohm interpretation is explicitly non-local).
Jerry Yager
Jerry Yager 3 日 前
It's just more ludicrous BS coming out of the physics community. I love science, and especially physics, but I get the idea we need a new generation on board for some fresh, sensible ideas.
Inferno Dragon
Inferno Dragon 3 日 前
Watched the whole thing and didn’t understand anything…
be the genius
be the genius 3 日 前
Torleda Murray
Torleda Murray 3 日 前
The World's aren't parallel...nor are they the same...and there is more than two of you....there is actually four of you but think of it as one divided into four lots of conscious energy (including you) it takes all four of you to have this experience, without four it is not possible naturally...maybe synthetically but the risk is that you don't come back as you need the you that is the "operator" that you has to stay behind in your body & keep the quantum tunnel / bridge / Stargate / if go back in time the operator can give you access to memory or energy memory which you can then intercept or trace someones thoughts from a place & bring them into the place (it would seem to them like they are dreaming...& You can then provoke them to have thought or remember and you can parallel their mind to obtain an answer...kind of like a ghost in a dream of "the dreamer that isn't dreaming" but has been bought there, & the ghost t can see what the dreamer is thinking about and can trace energy of anything from that point back & forward.its very complex to explain
Gilberto Zuniga
Gilberto Zuniga 3 日 前
What a bunch of bs- a cat alive and dead at the same time.
Teodor L
Teodor L 3 日 前
Not sure why this theory would entail that all that can be true (e.g. him being president) is true in some alternative world. He says himself that nobody is sure whether there is an infinite number of alternative worlds, and given this, wouldn’t it be a bit too bold of an assertion?
Every human is a "world" and we live in a parallel reality. Nothing exists, except your mind, to you. Without mind, you have no thoughts, no dreams, no communication at all with the other parallel worlds around you. As a person deeply into particle and motion physics, I consider the idea of other realities happening simultaneously is only possible when one considers the dimension of mind. Mind is an extra dimensional reality within the 3D physical reality and 4th dimensional reality of time. So, mind is a 5th dimensional kind of reality. FYI... physicists are among the most argumentative humans you will encounter. Professors will "profess" the current dogma which is "Big Bang" oriented, but that is a creationist myth and all the things like an expanding universe are quite easily explained with other things such as our basic misunderstanding of red shift, and net motion. i.e. We NEVER move in an ellipse, nor circle. We move in a helical wave through space. At the most recent convention of people who are working on this kind of stuff have agreed that they can only come as close to reality by using 8 dimensions. Dimensions are NOT things... they are a measurement. Alternate dimensions are nothing more than a means of measurement.
ANGELiki1992 4 日 前
This is the first time I've seen a video with NO dislikes. WHOA.
The Earth
The Earth 4 日 前
Entanglement heh? Yes, of course. That's the state of my synapses after watching that. 💢🧠
Anas Albounni
Anas Albounni 4 日 前
the many worlds is unprovable it’s just fiction , so stop considering it science, it’s just our understanding and how much we know that is short
I don’t understand any of this lol 😂
Amrendra Pandey
Amrendra Pandey 4 日 前
Good to hear it explicitly that the division or the way Sean Carroll defines, kind of unfolding of the universe upon the occurrence of an event, also happens by human actions. If so, it all becomes more attuned to a universe that is ultimately stuff of consciousness, a kind of mental activity. The way we know the matter, all the rest of our knowledge and intuitions go in vain. Also, I find the word 'branching' a bit unfit as it involves images with physical motions, something drifting off, on the top of the distinction made by the separation of many worlds. Like expanding the universe, that should not be the right picture. In this view, too, all (branching) is happening in the same space, if I understand correctly.
Stan Harris
Stan Harris 4 日 前
At 17:00 Sean talks about cognitive bias. The 0%/50%/100 probability shortcut is risible in light of statistical theory, but still in all, we’re evolved beings, not math machines, and we and our ancestors evolved for survival related quick decision-making. Not possible if we had to consider all probabilities in real-time.
0 Days Without Incident
This reminds me of a question that a friend asked me once. It was "Say you blew a bubble. It's perfectly spherical, and it's ever-expanding. Say you also have a needle, but you want to get it through the bubble. How do you get it through one side of the bubble to the other without going over the bubble and going under the blue?" I think that maybe this is the question that we should asking because this might help us get out of our universe and go to other universes.
Stan Harris
Stan Harris 4 日 前
My tentative conclusion is that Schroeder was a dog person, not a cat person, but only in our universe. There’s another universe wherein someone very similar to Erwin was a cat person.
Neil Libertine
Neil Libertine 4 日 前
If space or spacetime more flattened at a distance far from massive object then due to less curvature of spacetime, objects moves faster. So radial force from centre is more for distant objects. First they have to admitt there is no dent in vacuum, second distortion is due to force then why they rant that gravity is no force, third how radial force needed by orbitting object is provided. For any constant path either there is no force or balance of force. Without force there is no closed path. Then why they are using laplacian equation which only omit source but not potential and gradient. If mass causing that then how it is different from Newton's law.
Crooked Desk
Crooked Desk 4 日 前
I suppose the "infinite realities" kind of coincides with the idea that there is an infinite amount of 3rd dimensions making up the 4th. I've always struggled to visualize the concept but I suppose if every single branch from the dawn of time to the end (are there such things?) makes up one of these infinite 3rd dimensions, and the 4th dimension is just the collective interaction of these branches that makes things a lot easier to grasp. I suppose that would mean our 3rd dimension is made up of all the branching realities of the 2nd, wouldn't it? No idea if that's a reasonable conclusion or not, but that's where my mind went after this video LOL
Jagar Tharn
Jagar Tharn 4 日 前
What does it mean to say that things for which there can be no empirical evidence "exist"?
Devas 4 日 前
you are the modern albert einstein
Nicolas Ramirez
Nicolas Ramirez 4 日 前
Sean’s answer to the conservation of energy objection feels like a total non answer
Bonobo 日 前
Mostakim Kabir
Mostakim Kabir 4 日 前
If we find a theory of everything, does that mean physics is complete?
Declan Cunningham
This has been my favorite veritasium video so far.
Melanie Busch
Melanie Busch 4 日 前
all this is just things that us humans can perceive and its the easiest way to express ist but there is so much more outside of what we can perceive and calculate
Mr. Bro bro bro
Mr. Bro bro bro 4 日 前
If this theory really true, pretty sure I’m still inside the bed in other universes.
slottygaming 4 日 前
If this is true, then there’s one world where I do literally everything right and never did anything embarrassing… Damn that lucky guy
OrbitTheSun 5 日 前
With Occam's razor, you can estimate that the simulation hypothesis is a million times more likely than the many worlds hypothesis.
Ste Co
Ste Co 5 日 前
Why does the collapse of the wave function have to be an observer. Why can’t ANY interaction with any matter or any other wave function determine reality. Then there’d be no branching and the universe is just determining itself
Sharad Dahal
Sharad Dahal 5 日 前
Proposed my crush. She accepted.. In parallel world...
Eun Kim
Eun Kim 5 日 前
Can you make δ(x) a topic sometime?
Zed Dot Ess
Zed Dot Ess 5 日 前
The dead [cat] only know[s] one thing: it's better to be alive.
Eun Kim
Eun Kim 5 日 前
18:00 "God doesn't know about branches, there is the wave function of the universe that's all that really exists" answers it all in one sentence this seemingly complex idea
Nagida Sylph
Nagida Sylph 6 日 前
9:26 If you want to see something that's both alive and dead, you can speak to me any day
Ibrahim Baghdadi
where did parallel worlds come from and why did they have a beginning?
Abdul Halim
Abdul Halim 6 日 前
If a parallel world exist s it's like anime but it's in( IRL) but there is a chance the. Someday in human knowledge we can go to the parallel world .
d96091 6 日 前
This is how Santa Claus delivers presents to everybody in 1 night
The earth is a multi story building there are stories above us and below us but we only see the story we live on.
Adam Barcroft
Adam Barcroft 6 日 前
You prove that there are no parallel universes by making a choice and collapsing the wave. You leave only one out come. The cat is dead or it is alive. Without measuring it and knowing which, you have the "potential" of both outcomes. You do not actually have both. Upon measurement only one out come is true and you no longer have the "potential possibility* of the other. There's not infinite versions of yourself making different decisions. Only 1 you and the potential of what you can and might do until you decide. You'll never have the cat both dead and alive only the potential possibility of one or the other until one becomes reality.
Jacob Schreiber
Jacob Schreiber 6 日 前
So are we the original or are we just one of the branches? Also, if there are 5000 more branches made/second/person, and since the number of branches grows exponentially, does that mean there have been near infinite branches since the beginning of mankind?
Medico Tonic
Medico Tonic 7 日 前
Who are all here after watching king eternal monarch of lee min ho
Nick Iacovou
Nick Iacovou 7 日 前
Excellent video, one of the best. Now i'm going to watch The Matrix haha
Kenn Mossman
Kenn Mossman 7 日 前
so the concept of 'many worlds' is an artificial construct that makes life easier for physicists.
Nicolas Ramirez
Nicolas Ramirez 4 日 前
Well put
Guillaume Geaymond
ok I need somebody to enlighten me here. for me this theory is close to useless for the following reason, but I may be mistaken: the way I see it the many worlds theory only works if you have no way to interact with other worlds, in other words, it only works if you have no way to prove it. So all in all it's at most a more intuitive way to describe our universe, but with zero implication. Or did I miss something ?
Kaiser Soze
Kaiser Soze 8 日 前
Just to iterate, like the copenhagen interpretation, there is ZERO experimental evidence for this many worlds idea
P S 8 日 前
I went on a strange thought journey after watching this video. It was fun. What if the Many Worlds was a true reflection of reality, but what if it was a splitting of the Time Dimension at the point of every ‘decision’ or ‘observation’ that was actually occurring. We’ve come to understand more about spacetime in the last century, and there has been talk of further spatial dimension, like the curled up, hidden dimensions of string theory. But I’ve wondered for a long time now, what reality would look like with two or more dimensions of time. This has proved impossible for me to visualise if you could move freely within 2 or more time dimensions, as you could in 3D space. But if each were exclusive from each other, i.e. our single dimension of time was split into 2 dimensions at any given point, and you could only experience progressing through one, then the other(s) would be permanently hidden and shut off from you. Both could occupy the same 3D space without inference (and this would not require the duplication of the whole physical universe). You could have an exponentially increasing stack of realities, wholly exclusive from each other, but still inhabiting the same 3D space, each providing its own unique reality, but part of a larger hidden higher dimensional multiverse. Furthermore, what if these many worlds, whilst existing entirely remotely from the others, had a negligible, but non-zero influence over each other? This would increase over time, with every ‘generation’ of the time dimension fractures. In my mind, this could be analogous with Dark Energy, which is apparently gaining in strength and driving the accelerated expansion of our universe with the ‘increase of’ time. Somewhat fell down a rabbit hole.
Hunter Calhoun
Hunter Calhoun 8 日 前
Only part I understood was about Norton LifeLock
tomcat tomcat
tomcat tomcat 8 日 前
IrokoSalei 8 日 前
2:40 "The wavefunction collapses instantly and irreversibly" This is misleading and I think you already made that mistake with the double slit experiment. If you detect the photon at one slit it will still diffuse on the screen behind, not go straight like a tennis ball.
Jannes van der Velde
No nothing there i bin there lol.
Suyog Kadam
Suyog Kadam 8 日 前
In 1 world I am watching this video, in other I'm sleeping
detail 8 日 前
You lost me at "Quantum"
adamndirtyape 9 日 前
Unless one of those versions of me in a parallel world puts more money in my pocket then I couldn't care less if they exist.
Neil Libertine
Neil Libertine 9 日 前
Space is not physical thing so immeasurable, only distance is. Similarly time is product of motion and measurable time as interval is result of periodicity or frequency. So mass cant in any way distort space or time. Suppose there is a box having volume of 1 litre space. An object of mass, 1 gram having volume of 0.25 litre thus having density of 4 gm/lt is placed in the box. Now replace it with an object of 1 gram and volume of 0.5 litre having density of 2 gm/lt, half of replaced object. Question is which object distort space more, having more volume and less dense or less volume and more dense. Obviously one having more volume, thus the idea of mass or density distort space is ridiculous.
Wael Atalla
Wael Atalla 9 日 前
This topic makes me more unable to believe people around me, they tell me I'm smart, but I truly doubt it now. Maybe I'm smart and "not-smart" at the same time.
Anandh Balakrishnan
So, what happens if i make zero choices or entangle as low as possible with the environment around me? Will doing nothing still create these sub divisions of the original wave function or simply identical copies of itself?
Andrew Britton
Andrew Britton 8 日 前
This is impossible, like he said millions of particles are decaying in your body every single second, so there is a mind boggling number of branching even if you just sit there. Theoretically a small collection of particles can be kept in a super position, but the more particles you have the harder it is to prevent it from interacting with the environment and becoming entangled. For a whole human being it would maybe be “theoretically” possible, but it would involve killing you by freezing you at absolute zero in a vacuum, or some other unpleasantness.
S Ali
S Ali 9 日 前
Read Surah Al Mulk
Divinity by curiousity
I think whole quantum physics is like religion if you don't have any idea about nature of fundamental thing but you have to move on with it by just believing that maybe it's both the possibility. And slowly you start proving one thing or another because you included both the nature of that fundamental particle..one way or another you justify yourself
Dustbunni 10 日 前
garlicbread blocks
They dont because if they exist there will probably be a universe where paralel universes dont exist
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