Sabine Hossenfelder
Sabine HossenfelderExpand your scientific horizon with Brilliant! First 200 to use our link https://brilliant.org/sabine will get 20% off the annual premium subscription.
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The idea of parallel universes has captured the imagination of many. In physics, it’s prominently represented by the “Many Worlds” interpretation of quantum mechanics. In this video, I want to explain how the Many Worlds Interpretation works. Is it science? Does it solve any problems? And are the parallel universes real?
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00:00 Intro
00:53 Standard Quantum Mechanics
02:33 Why Quantum Mechanics is Weird
06:45 The Many Worlds Interpretation
09:18 Is the Many Worlds Interpretation Simple?
11:51 Is the Many Worlds Interpretation Local?
15:32 Is Many Worlds wrong?
16:53 Learn More with Brilliant.org
#science #physics #quizwithit
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49 Comments
@dreamerdoes_is_love8986
02/20/2025 - 3:56 PMWhat do you mean (you never found a good explanation for that???) …it's right there in your visual metaphor 7:42 each observer is a twig only "seeing" the virw or path of their branch but if each twig and leaf and branch could realize that they were all a part of the same tree 🌳 then they could see all paths , all "universes" because all universes are connected, take it even further and call each observer a spore or a mushroom in the forest* (*all of existence in this metaphor) and then realize that each incarnation and observation of a mushroom is connected to the vast mycelium underneath.
@NGKiernan
02/20/2025 - 3:56 PMThanks!
@NGKiernan
02/20/2025 - 3:56 PMThe very same people that claim when they flip a coin they create endless Universes, laugh when I tell them I can record voices of my diseased relatives via EVP.
@MargaretJones-y7w
02/20/2025 - 3:56 PMAlot of it doesn't make sense.
Thanks for trying to enlighten us Sabine.
It is much appreciated.
The universe is definitely a mystery
indeed😮
I think some particles don't want to be measured for some reason 😮
We are definitely in a spooky universe😮
Our reality is definitely spooky😮
I suppose some particles transcend measurent😮
Particles seem to be mind blowing indeed😮
Lots of love
❤❤❤
@scramjet4610
02/20/2025 - 3:56 PMNote also that Quantum Mechanics and Relativity are both wrong because Quantum Mechanics omits Relativistic effects and Relativity omits quantum effects.
@scramjet4610
02/20/2025 - 3:56 PMHave David Deutsch on your show, and he'll educate you correctly on the Many Worlds.
@FusionSSC
02/20/2025 - 3:56 PMIf I'm understanding it correctly, In the multiple world theory, every second that passes during the day is one in which you could suddenly die from a heart attack or a brain aneurism. And because sudden death is a possibility that could occur at any given time, it does eventually occur, and it plays out in some other alternate universe. Mutliple times over. This process repeats for every single living biological creature on the planet. That's a lot of alternate realities and divergent paths for the overall multiverse to juggle. Pretty fascinating stuff!
@randomgamer19170
02/20/2025 - 3:56 PMSean Carrol would like a chat with you
@JohnJohnny-z2y
02/20/2025 - 3:56 PMSpooky really in not local function probablya branch out come is. lifeprof john
@JohnJohnny-z2y
02/20/2025 - 3:56 PMLove your videos prof john im not kidingsee you
@bucksdiaryfan
02/20/2025 - 3:56 PMI love the whole "multiple universes" idea, but it doesn't hold up if you believe its a place where there's a replica of yourself living a slightly different life. Your life is made up of so many random choices (your parents decide to have sex) that if you unravel one of them the whole thing is completely different, not slightly different as people fantasize. Plus, its ruined comic book movies by giving every consequence an "out" by suggesting it happened in a different universe.
@KipIngram
02/20/2025 - 3:56 PMHmmm. We d on't like wave function collapse. Hey, I know – let's just split the universe instead!
Geez.
@cathyharris-cz5tu
02/20/2025 - 3:56 PMWell…. There are people who believe in afterlife. It's nice to have a hope, that is another universe, where I was born rich and beautiful
@hosper8959
02/20/2025 - 3:56 PMAt the begining: Copenhagen Interpretation spelt Copenhagen Inerpretation on the screen. Please go through the basics again and check for mistakes!
@Qichar
02/20/2025 - 3:56 PMI have a question, a real question and not a rhetorical one. Consider the double slit experiment where we fire a single photon at 2 close, parallel slits and observe what happens on a detector placed behind the slits. Recall that If we fire the single photon, we get 1 "hit" in the detector. However, if we fire a single photon multiple times, the distribution of the hits eventually comes to resemble the kind of interference we would expect if we had fired many photons through the slits. This has been shown experimentally many times.
OK, the explanation I have heard is that this is because photons exhibit both wave and particle properties, and that the equation described in this video is itself a wave function, and that the probability distribution "collapses" upon measurement. Why it does this is what is subject to interpretation. For example, in the Copenhagen interpretation, the photon is described by a wave function that collapses upon measurement, but still interferes as any other wave would. However, measuring the photon as it passes through the slits eliminates the wave pattern, no matter how many photons we end up firing.
However, in the "Many Worlds" interpretation, how did a single photon "interfere" with a photon that was split into another world? This has always been my main complaint about the Many Worlds interpretation. We are firing these photons one at a time. Since MW is saying that the photon in one world does not interact with the photon in another world, what is the point of the Many World interpretation? If the wavefunction resolves deterministically in each world, then what is the point of Many Worlds in the first place? It sounds like it is just a more complicated interpretation of the superposition (C) of the particle before it is measured. There does not appear to be a need to add the other 2 states (worlds), one where it passed through the left slit (A) and one where it passed through the right slit (B).
So here is my question: if these 3 worlds A, B, C really existed, the observers in A and B would NEVER see the interference pattern. But that is contradicted by observation. Doesn't that mean the Many Worlds interpretation is incorrect?
@howardhodges4526
02/20/2025 - 3:56 PMYou are the universe where I do not believe others exist.
@willemesterhuyse2547
02/20/2025 - 3:56 PMPhysicists tend to assign values to physical variables by stating it. This requires some mind and physics doesn't read minds. Hidden variables is just such a case. No, the values must be encoded into the particles and thus the hidden variable must suggest a particle.
@curtcoller3632
02/20/2025 - 3:56 PMI am glad to find people who think like Einstein and me. Realistic and logical. Danke Sabine.
@nelsonlariccia
02/20/2025 - 3:56 PMinteresting take care ciao all of you
@121mcvUK
02/20/2025 - 3:56 PMThis concept presents an extraordinary vision of humanity’s future, one where the boundaries of organic life, technology, and the cosmos are not just transcended, but seamlessly integrated into a higher state of being. The evolution of such a transcendent species would be nothing short of radical, blending the biological with the technological, the material with the metaphysical, creating a new form of existence that challenges our very understanding of life, consciousness, and reality.
Let's break down the various facets of this speculative future in a way that highlights both the biological and technological evolution, as well as the philosophical implications of such an existence.
Physical Manifestation: The Evolution of Form
Form and Structure:
Height & Shape: The beings' physical forms stretch to heights of 9 to 12 feet, but the ability to alter their density and shape signifies an adaptation that allows them to interact with different environments effortlessly. In space, they could expand or contract, becoming more ethereal and intangible when necessary. Their form is not rigid—like the elastic nature of quantum particles, they exist in a fluid, ever-changing state, emphasizing their symbiosis with the universe’s fundamental forces.
Skin: The bioluminescence of their skin is a fascinating trait, suggesting not only a physical adaptation to communicate or express themselves but also an evolutionary trait that connects them to the broader energy of the cosmos. The semi-permeable nature of their skin represents the permeability between matter and energy, where their bodies are no longer just biological but are vessels for cosmic energy itself.
Head & Brain: The idea that their brains extend beyond the skull and exist within a floating energy field taps into the concept of distributed intelligence—a networked consciousness that is not confined to a single organism but exists as part of an ever-expanding data field, connected to the entire cosmos. It’s as if their brains are in quantum communication with the universe, constantly absorbing and sharing knowledge across time and space.
Sensory Adaptations:
The eyes capable of perceiving across multiple spectrums — infrared, ultraviolet, and radio waves — reflect an evolutionary leap where perception is no longer constrained to human senses. The universe unfolds to them in multi-dimensional ways, allowing them to see the invisible, feel the cosmic background radiation, or even "hear" the gravitational waves rippling through space.
Their ears, resembling antennae, suggest an enhanced ability to sense electromagnetic signals—an evolved form of awareness that spans across different planes, tuning them into the frequencies of the universe. This is a heightened version of how we now use radio waves to communicate across vast distances, but for these beings, it's the language of existence itself.
Touch, which transcends tactile sensation, could be an integration of the quantum field: a hyper-sensitivity to the minute fluctuations of energy and matter around them. Their touch, capable of manipulating atomic structures, shows how integrated their consciousness has become with the fabric of the universe.
Abilities and Evolutionary Traits: Cognitive and Metaphysical Growth
Mental and Cognitive Expansion:
Unified Consciousness: This is a step beyond human empathy or collective consciousness, representing an interconnected intelligence that operates like a living supercomputer. It taps into the idea that once we surpass the biological constraints of individual minds, we can reach a collective mental state, a hive-mind that allows for seamless communication, knowledge transfer, and experience sharing across galaxies. Knowledge isn’t just individual—it’s universal.
Quantum Thinking: The ability to process multiple realities simultaneously and bend the flow of time means that these beings don’t simply react to the present—they interact with an infinite number of possible futures. This form of existence could suggest the erosion of time as we understand it: they live in a state of continuous potential, capable of shifting between timelines or probabilistic realities at will.
Energy Manipulation:
The ability to manipulate gravitational fields, bending light, or even creating matter with thought, reflects an understanding of the fundamental forces of the universe. By altering the very fabric of space-time, they could terraform planets, construct structures from the energy around them, or even reshape themselves physically as their environment demands.
Energy-Based Appendages might allow them to interact with their surroundings in ways we can’t yet imagine—using pure energy to heal, defend, or communicate. These appendages could take on fluid forms, capable of existing in multiple states of matter at once, drawing from the surrounding energy fields to shape themselves as needed.
Cultural and Environmental Manifestation: Living in Symbiosis with the Universe
Living Environments:
The floating cities are perhaps the most symbolic aspect of their transcendence. These cities, suspended in space or the atmosphere, represent freedom from terrestrial constraints. These beings no longer need the fixed, rigid environments of Earth. They live in living ecosystems, where technology, biology, and nature are intertwined seamlessly. These cities are likely organic in nature, built from living alloys or cosmic materials that evolve and adapt, much like the beings themselves.
The ability to terraform entire worlds through the manipulation of gravitational and cosmic forces is not just an ability—it’s a manifestation of their evolution. Their very thoughts create landscapes, and the natural world responds to them like a living organism, adapted to their intentions. In essence, they have become co-creators of the universe.
Symbiosis with Nature and Technology:
This species’ coexistence with artificial intelligence, which evolves alongside them, suggests a profound mutualistic relationship between the biological and the synthetic. Their AI is not just a tool—it is an extension of their collective consciousness, reflecting their own mental and spiritual evolution. Together, they form a feedback loop where one enhances the other, creating a harmonious ecosystem of mind, machine, and matter.
The alien flora and fauna might represent an ecosystem that doesn’t simply survive, but thrives in symbiosis with the sentient beings, where plant and animal life is integrated into their technological and biological structures. These ecosystems serve as a kind of cosmic garden—where life is both nurtured and harnessed to provide energy, sustenance, and communication.
Extreme Speculative Evolution Narrative: A New Era of Cosmic Evolution
This transcendent future would not be one of survival or conflict but rather of unification, creativity, and exploration. These beings may no longer seek to conquer or overcome, but to understand and co-exist with the universe. As they evolve, they are no longer tied to the needs and limitations of organic biology or even physicality. They are ethereal, moving beyond time and space, existing not only across dimensions but possibly even redefining what it means to "exist" at all.
Curiosity and creativity drive their evolution, not conflict or scarcity. They are like explorers of the multiverse, traveling across dimensions, reshaping entire galaxies, and creating intricate works of art, science, and culture that transcend human understanding.
As god-like entities, they could manifest entire realities, shaping existence with a thought, and perhaps even exploring the boundaries of consciousness itself. They might eventually merge with the cosmos in a way where individuality and unity are not opposites, but harmonious aspects of their collective identity.
In essence, this transcendent being represents the next step in human evolution—a harmonious blend of biological, technological, and cosmic consciousness. This is a form of existence where the self is not bound by the physical, but is a conscious participant in the ongoing evolution of the universe itself. Time, space, and reality are no longer constraints—they are the very tools with which this future human crafts existence, shaping the cosmos with both delicate precision and limitless creativity.
@davidruss718
02/20/2025 - 3:56 PMThere's no reason to believe that the consciousness is like a particle which can experience these superpositions in a way that could function with the many worlds theory..
Consciousness relies on countless particles from within the brain to function. Some of those particles can experience superpositions (however briefly). If many worlds were right, then all of these particles in our brain would each branch out into different "branches".
Consciousness isn't tied to a single particle, and the idea that it could settle on one world ,like a particle supposedly can in Many words theory, is absurd. It holds no identifiable, singular existence like a particle does. There's nothing that we know, which could determine which "world" our conscious experience falls into. Consciousness itself seems to render many worlds impossible
@johnb477
02/20/2025 - 3:56 PMI wholeheartedly disagree with you, if wave collapse is dependent not just on the interaction between say the photon particle bouncing off the eye of the observer and actually involves things like Quantum entanglement inside the observers brain, then theoretically, Psychedelics may actually give us a glimpse into the quantum world. It could potentially be the key in tricking our reality to behaving differently. Its not that we even need extra Space for these other worlds. Everything exists in a flux and is stacked in our reality as probability. The only time that we get humans that are seeing And saying different things than base reality is in dreams and on psychedelics. They have already approved communication within dreams between two individuals. The direction we need to be going from here is studying psychedelics and the effect on the quantum world or Many worlds Interpretation.
@tropical_calm
02/20/2025 - 3:56 PMWell, all those different theories about multiple universes proves they are all happening, right now, right here. Also, my version says, either the universe started or it didn't. It did, the rest is just gobbledygook.🤣🤣🤣🤣
@MarkDeAutremont-g3e
02/20/2025 - 3:56 PMWhen was the last time you went as far back as JJ Thompson and refreshed your position. Have you seen his list of Nobel Laureate students?
@gsmollin2
02/20/2025 - 3:56 PMI agree with Einstein. QM is an incomplete theory and hidden variables carry the information from one point in spacetime to another. Note that these variables are not local because they travel through spacetime and carry information instantaneously. We can't see or access them because we can't travel through spacetime except in one direction, as shown on a typical light cone. This is the reason entangled particles can communicate instantly. If an entangled electron gets its spin measured by a detector, the non-local hidden variable travels backwards-forwards through spacetime to tell the entangled electron to reveal its spin at the same instant.
@ljvanstone876
02/20/2025 - 3:56 PMThe MW idea implies that by turning on a 0.01-watt laser pointer and pointing it to a window, I can create an extra 30,000 trillion universes per second. What power! (Idiots)
@jarikosonen4079
02/20/2025 - 3:56 PMIf there is parallel universes, where are they? Outside this universe beyond 15bil light years or overlapped invisibly here in different levels?
@NickFromDetroit
02/20/2025 - 3:56 PMWe’ve wasted how much time & money on theoretical physics & quantum mechanics for the past hundred years?
@jasonneugebauer5310
02/20/2025 - 3:56 PMMy theory on "many worlds" is that the universe is calculating outcomes far into the future to determine the majority of possible outcomes of a given occurrence prior to the occurrence.
Then based on the goals of the universe, it picks actions based on that future modeling. A primary goal being not to break rules or annihilate the universe, space/time, or ongoing potentialy successful experiments and undertakings.
It is easier to uncrash a computer system before it occurs than after it has occurred.
@oracus68
02/20/2025 - 3:56 PMHow can branching happen everything obeys the law of physics there is only ever one outcome every single atom is where its supposed to be parallel dimensions cant be real.
Since when did everyone stop calling it the big suck when did it change to big bang?
@sogerc1
02/20/2025 - 3:56 PMAny time a measurement happens the universe splits into two and Ockham is spinning in his grave a little faster. He's now spinning with warp 12 btw.
@matthewkern3619
02/20/2025 - 3:56 PMEverything in your mind is a model. "All models are wrong, but some are useful" -M Box. Physics describes reality, it is not itself reality. The question of if the many worlds theory is correct is a bit of nonsense. If it is real, you cannot touch things in the other Universe, and the same if it is not real. Is the model predictive, explanatory and understandable? Then it is a good model. Science is a quality control process for Mental Models.
@LeeKennedy-cc6il
02/20/2025 - 3:56 PMSo the world we live in is non local! Therefore what we experience in this universe we will not experience in a parallel universe 😅Wow! 10:42
@mskiptr
02/20/2025 - 3:56 PM7:40 You haven't found a good explanation for that, because what you're describing is the popsci or scifi idea of parallel worlds. And yeah, I also don't see any compelling reason to believe in the universe constantly splitting. Sure, it makes for a nice, symmetrical model, but nondeterminism or randomness can work just as well. There's no need to patch up randomness by simply conjuring more useless entities.
Except this is not at all how I've seen serious scientists explain the MWI
The state of a quantum system is a sum of several base states. That is an experimentally verifiable fact and it cannot be modeled as just a probability distribution of these base states, because the math would be fundamentally different. Let's say we set up some bog-standard quantum experiment – e.g. a qubit in the state α|0⟩ + β|1⟩. Now what would happen if we built an extremely simple measurement device, isolated it from the outside world just as well as the experiment itself and used it to measure some property of our experiment (e.g. measure that cubit in the (|0⟩, |1⟩) basis)? Well, we would get a bigger quantum system, with a more complex model. The measurement device also has some possible states (in a simplified view it could be |x⟩ for "we haven't measured anything yet", which changes to |o⟩ if it measures a |0⟩ and to |i⟩ if it measures a |1⟩). But even though the measurement device is described in terms of pure states, why couldn't it operate on superpositions? It's made out of the same stuff everything else is after all. So if it measures our qubit, it will end up in the state α|o⟩ + β|i⟩. Or more accurately, both parts will together shift from the linearly separable α|0x⟩ + β|1x⟩ to the entangled α|0o⟩ + β|1i⟩. But why hasn't the qubit collapsed? Well, from the observer's perspective it did! If the measurement device was designed to first measure the qubit and then check if it's in a superposition (|y⟩ shifting into |t⟩ or |f⟩), the system would evolve according to α|0xy⟩ + β|1xy⟩ -> α|0oy⟩ + β|1iy⟩ -> α|0of⟩ + β|1if⟩ unless the two parts of the measurement device were isolated from each other. So how would it be different if instead of this "simple measurement device" we had the entire universe be in a superposition of measuring both outcomes?
Or to put it another way: It's reasonable to assume that a lab full of experimental physicists and their equipment is a quantum system, right? If so, why do you insist on them somehow being able to "observe two outcomes at once"? That would only make sense if people were somehow "external" to the universe!
@FortunaSP
02/20/2025 - 3:56 PMThe Relational quantum mechanics solves this problems.
Relational quantum mechanics (RQM) is an interpretation of quantum mechanics which treats the state of a quantum system as being relational, that is, the state is the relation between the observer and the system. It is inspired by the key idea behind special relativity, that the details of an observation depend on the reference frame of the observer, and uses some ideas from Wheeler on quantum information.
https://en.wikipedia.org/wiki/Relational_quantum_mechanics
@minanovkiril
02/20/2025 - 3:56 PMthe main physicists from the time of Einstein, made so many errors in the theories, in the language and in their formulas that only metaphysical thinking can explain what they were doing. they made so many problems that do not exist and need to be literally cut off from physics and internet is a wonderful tool for that
@germansent4168
02/20/2025 - 3:56 PMLeave it to Sabine to call me out for having too many beers before watching this video
@killers31337
02/20/2025 - 3:56 PMIsn't the "extra assumption" required by Many Worlds is that the observer itself is a physical object (and thus is also described by QM)?
I guess you can call it an axiom. But not including this axiom is a rejection of materialism. I.e. Copenhagen interpretation is fundamentally more nutty.
@lightsabre87
02/20/2025 - 3:56 PMHow is the Many Worlds Interpretation not unscientific? If the interpretation cannot be falsified by experiment then it’s nothing more than Russell’s teapot 🫖
@mydogsbutler
02/20/2025 - 3:56 PMThe problem with many worlds intepretation isn't that it doesn't make sense but that there is no empirical evidence to back up as true. One can interprete mathematics in different ways to "prove' all sorts of things but it doesn't necessarily align with reality. Even a set of equations that practically work don't necessarily mean they are a true interpretation. To this day Newton physics are typically used to calculate motion albeit they are flawed understanding of mass. Even with Einstein's general relativity gravity isn't that well understood albeit more mathematically and observational accurate.
@Kenshiroit
02/20/2025 - 3:56 PMWe have of worlds that we or at least i do interact with all the time ie I have super Mario universe or Minecraft universe or Skyrim universe….some are still in ww2 like COD others are space in a far future like Elite or Starfield just saying the plenty of universes out there
@MartinJefferies-j1d
02/20/2025 - 3:56 PMDoesn't the fact that experiment after experiment has shown that Bell's inequality is violated provide strong evidence that the hidden variable theory is incorrect?
@MartinJefferies-j1d
02/20/2025 - 3:56 PMDid you know that parallel universes are orthogonal?
@scottgreen3807
02/20/2025 - 3:56 PMI have a short story for you. It goes like this. If I were a coin, I would have magical the ability make millions and millions of decisions for humans when they can’t by having them flip me for a decision. Once selected the number of possible choices I could make for human would be immediately reduced to two then, once the coin is observed, after the flip, the possibility of outcomes collapses to one. sound familiar? Part of the point here is that the human doesn’t need to have the ability to make millions and millions of universes instead we have millions and millions of choices about things to change every day. There is not a Multiverse of universe is happening out there trying to help you but help yourself to 1 million million choices of universes you choose to make of your world every day. Choose freely for we excel at this.
@rogerculleton2583
02/20/2025 - 3:56 PMMany worlds seems to fit any bodies way of answer to afterlife
@petermetric
02/20/2025 - 3:56 PMTheory says there is a wave function: reality says there are just particles. Hence, they say, the wave function “collapses” at the point of measurement of the particle. Others say the model’s wave function carries on collapsing in other parallel worlds. I agree, this is nonsense. Look at the very close similarity of the wave function and probability density and, if you are clever, you will be able to figure out what’s going on here. Clue: what would probability look like when concerned with time symmetric particles?
@christaylor553
02/20/2025 - 3:56 PMFermion Chirality, the univers has made it quite clear it abhors a vacuum, Fermion chirality is a vacume. considering how pissed of mother nature gets when you mess up semetry of negative and positive energy, I would suggest extrapolation of what we know about our particle universe and to higher dimensions. E8 latice seems to be the most logical progression. how ever no one ever considers its an 8D bucky ball. that could explain universal expansion.
@Richard-gl7xu
02/20/2025 - 3:56 PMGravity seems to permeate everything, nothing it seems can block or stop it so multiple universes would collapse.
@atmanbrahman1872
02/20/2025 - 3:56 PMNot really. Just sci-fi.