As an engineer, I performed a quick estimate and determined that we have at least one world in existence. The remaining calculations are beyond the scope of our current budget.

“Friends don’t let friends go through beam splitters” - wise words to live by 😂

7:40 I always assumed that the observers *did* split. So the question 'why do we only experience one of the worlds' would be answered when we realise that there would be a gazillion other 'replicas' of us asking the same question in their own world.

The point that hidden variables theories have NOT been ruled out by experiment is an extremely important one, and it should be hammered over and over until the myth is dispelled (and then some more to kill it while it still goes around as a zombie). And I think you're doing a huge service to physics in highlighting it once more. Thank you!!

I would love to see a discussion about this between Sabine and Sean Carroll. He's a very smart physicist (formerly at Caltech, now at Johns Hopkins) who favors Many Worlds and who, like Sabine, has a great youtube channel (featuring lengthy interviews of other very smart people).

Hi Sabine. Here in Brazil, "quantum mechanics" means whatever you like!!! I have a coworker who is a civil engineer and she was teaching "quantum mechanics" to a handful of people from my job. I was like "well she returned to college to study physics". One day she started talking to me about such QM. Turns out it's a religion!!! More like horoscupus and sign mixed with spiritism (I guess?). The term "quantum dynamics " seemed to be for cosmetic purposes only... I was astonished!!! Can't believe it up to this day.

The way Sabine says ‘today’ is everything

Hi Sabine. I love your passion and commitment to getting physics right!

Asking why the observer "doesnt branch and observe all worlds" feels like asking why identical twins don't have telepathy. The observer *does* branch, and by definition, to branch is to become a different thing, with different experiences.

Hi sabine!!! Thank you for keeping us all updated on science news. I one day aspire to get a degree in physics, so thank you for keeping that sense of wonder alive!!

You are a most wonderful example of a thinker. Examine, test, observe, think. Love your videos and thoughts. ❤

This is an awesome video on the subject! I would love a dissection of the observer vs measurement aspect of this subject as well.

Bumblebees have no idea how humans can walk with those ridiculous legs

Sabine, which universe has a new video from you everyday? That's the one I want to be in.

8:38 - I love your stuff, Sabine and I am so, so thankful for all the knowledge you share. At that timestamp, I've often wondered the same thing about energy conservation and many worlds. Maybe I'm just bad with the math here, but I'm having a hard time trying to understand why the "branching universes / probability calculation explains why conservation of energy isn't violated" point you made. Maybe this is something you could do its own video on at some point?

I just love the topics and discussions! It keeps our brains from rusting out!! 😂😂🙏❤️❤️

Thank you for these amazing videos ! I always love when you talk about quantum mechanics. Can you please explain Nelson mechanics, whether it is equivalent to QM and what is entanglement in it ?

I love this channel. Your standup keeps getting better & better. Keep it up!

7:25 "The major challenge for many worlds is to explain why the thing we call an observer does not itself branch with those worlds and therefore see all the outcomes, but somehow randomly only experiences one of those worlds. I've never found a good explanation for that." Wait, what? But, that's precisely the major challenge for Copenhagen, not many worlds! Actually, that's WHY MWI is so nice: it's an interpretation QM that even *laypeople* can understand, and that, as you've admitted, *accurately* explains QM effects, including entanglement AND randomness. Except, in MWI, the source of both randomness and entanglement are incredibly intuitive: they're only "weird" when wearing a Copenhagen hat.

My understanding of many worlds is there is no collapse because the observation (or measurement) gets entangled with the result. The simplification of many worlds is the wave equations are reality and there is no collapse. They just keep deterministically following physics. However, when we observe some QM event, we get entangled and get all probabilities. However, we cannot communicate with the parts of us that saw different outcomes. It also sounded less like branching and more like subsets. Like there are an infinite number of points between 0 and 1. If you have an event that is 50/50, then one part of you gets 0 to 0.5 and another part gets from 0.5 to 1. However, both sections still contain an infinite number of points can be further subdivided.

"The major challenge [of MWI] is to explain why the thing we call an observer does not itself branch with the worlds" But in MWI, the observer *does* branch with the worlds. Suppose that, like Two-Face, I decide whether to comment on this video by flipping a truly random coin that's dependent on some random quantum event. Some other world has a me that decided not to comment on this video. I can no longer see the world thru his eyes, nor he thru mine, but we each see a consistent world, and we each see a single outcome for the coin-flip, even though in the larger picture both outcomes happened. "Not simpler [because] as we saw earlier, you need the collapse postulate to calculate probabilities" That's circular, since you couched the earlier discussion in the Copenhagen paradigm or something similar in the first place. As I was watching it, I was thinking "That's not right, observer-splitting does the same thing just fine" But I do want to thank you for introducing QB-ism, which I will have a look at.

7:28 - oh, c'mon, I didn't expect such a misconception from Sabine - observer also branches altogether with his/its consciousness if applied - every version of observer observe (or "experience") only its branch

Parallel Universes are real. You see, when mario builds up enough speed to cross 4 Parrallel universes in one frame (known as QPU speed), he can jump into a parallel version of the map that is outside of the bounds of the normal map. This map has no other actors and also no wall collision, so it is not as glamorous as you may think.

Your videos are Great Sabine, thank you 😁

Hello Sabine, I was once enamoured with MWI thanks to Sean Caroll but since than I grew more and more sceptical with it. Its there any video on youtube where you debate with him, or another MWI proponents about this topic? Although Sean Caroll is still one my favourite science communicators:).

As an observer you can branch into several realities just fine. They have very special pills for that.

I think it would be fascinating to have dinner with you and be able to ask you questions about the universe and science then sit back and listen to you explain!! Maybe in another universe I could..wish it was this one!!!!

Beautifully said and point well made. Bravo.

In a fraction of a second, we would have more universes as there are particles in the one we are living in. This seems like nonsense to me.

My understanding was that MWI was local because the "splitting" propagates out locally from the measurement. When A and B finally compare measurements locally that too is a split, except that impossible universes (where A and B both detected the photon) are excluded. But as far as A is concerned after her measurement B is still technically in superposition until B's measurement information actually reaches her, which is STL. Could be this is wrong but I've definitely seen this explanation before to justify MWI being local.

My understanding is that some variants of many worlds feature all the worlds pre-existing in some sense, rather than literally splitting. In these versions, measurement is simply a local knowledge update, so the theory is local in the sense that there is nothing “causal” happening at a distance. Of course, the more serious problem is how you are supposed to derive probabilities from within the interpretation

Thanks for the video; I always appreciate your common-sense takes. Notice also that for continuous variables, the number of worlds spawned is uncountably infinite. Good luck with the quiz app! I can only speak for myself, but I come here to get information, not to take a test.

I don't think it is an additional postulate that observers can only experience one branch rather than multiple ones. This comes out of the theory because you find that different branches evolve independently. Any scenario where you could feel yourself in a superposition would violate this.

The collapse of the wave function has always struck me as a mathematical artifact that only appears because of our insistence on stitching quantum systems with classical measurements.

I've casually accepted Many Worlds as a layperson for a long while and have done a lot of personal sci-fi exploration on the topic. As in, I assumed it was the prevailing accepted theory among academics. This is the first time I've seen someone break down why wave function collapse and many worlds are more equally matched than I otherwise realized and has shed some light on the process of academic disagreements. Makes you wonder if many worlds has so many staunch supporters _because_ of its sci-fi implications. Thanks, Sabine!

Sabine! I just heard about the double "time" slit experiment and I definitely want to hear you explain it! Please, please make a video covering the experiment where a laser beam goes through indium tin oxide and reflects onto a detector within a time frame of a few femtoseconds and the scientists measured an interference pattern in the wave's frequency.

07:40 The observer IS branched to the other worlds but since there’s no communication between the branches each branched observer sees only his version of the measurement.

It's could be "explanation" of literally anything. "Why did my poop smell bad the other day? Oh its because I just happen to live in a universe where it did. There were other universes where it smelled like a summer's day. There now I've explained it."

Hi Sabine, great job! I have to say the insistence on confusing model with reality is really a big problem for me, and a lot of physicists, specially particle physicist, seem to be tirelessly focused on that misguided assumption.

Hey Sabine, could you please make a detailed video on energy conservation in many world theory. Also, your videos are amazing.

In any case, the wave function describes my incomplete knowledge of everything.

around 7:25 you ask why observers only experience one of the branch worlds. This seems fairly easily answered if one considers an observation an update in an observers wavefunction. I.e. an observation behaves the same way as that which is being observed, with an update to its wavefunction.

The universe has no obligation to make sense to us.. Our persistence of “one theory” is what’s leading us to fantastical ideas.. If the model works, let it be and move on rather than romanticising about its implications.

I always have a preference for the simplest explanations. They're usually the ones that turn out to be correct, once we have a way to prove them. For that reason, while it may be an interesting exercise to consider the possibility of infinite parallel universes, it does seem to a bit of stretch for something that can be explained by something as simple as hidden variables (just properties we can't measure). That's not something we generally do in other areas of life.... thankfully.

Maybe the observer branches too. Each observer sees one outcome, the one that happens in his universe. But collectively, the observers see them all. Or most of them. In some universes, the observer might die the instant that the observation is made or would have been made.

Some people who play with mathematics make the mistake of thinking that they are dealing with the real world. Maths is fun, but let's keep our feet on the ground.

"We can neither confirm them nor rule them out" sounds exactly like the definition of unscientific to me.

Probabilistically, there are more realities in which Sabine believes in Many Worlds. Which gives me comfort

@02:14 The Copenhagen Interpretation !!

Also, I think the main problem with many worlds is they assume a correlation of outcomes; that the different worlds statistically matches the probabilities of different outcomes in this world. If that's the case, there must be a mechanism of correlation and so the other worlds will be in principle observable.

Thank you for bringing up this point about how a pure many worlds interpretation doesn't replicate born probabilities. Attempts to derive the Born Rule always seem to work by invoking a seemingly enticing assumption that ends up being equivalent to what they were trying to prove.

Your sense of humour is wonderful 😊

2:05 @Sabinehossenfelder: excellent video, as always. Your clarifications are very helpful! (Note: Copenhagen Interpretation is almost correct, except the Interpretation is missing the first T.)

you are the person who better explains concepts in the whole internet. thanks you are brilliant Sabine

1:36: 🌌 The Many Worlds Interpretation of quantum mechanics suggests that parallel universes exist where anything that can happen, does happen. 1:36: The wave-function of small particles, like electrons, describes the probability of finding them in a particular place. 2:00: According to the Copenhagen Interpretation, nothing has definite properties until it is measured. 2:28: The measurement problem in quantum mechanics refers to the switch from a particle described by a wave-function to a particle with a definite property after measurement. 3:07: Sending a photon through a beam splitter creates a superposition of possibilities, but measurement collapses the wave-function and determines the outcome. 3:45: 🔬 The video discusses the non-locality of quantum mechanics and the possibility of hidden variables models and the Many Worlds interpretation to restore locality. 3:45: Updating the wave-function is necessary to obtain correct probabilities in quantum mechanics. 4:14: The wave-function update is instantaneous and non-local, leading to the concept of 'spooky action at a distance.' 4:45: The non-locality of quantum mechanics depends on whether it is fundamentally correct or just a description of an underlying reality. 4:57: Hidden variables models propose that there is an underlying reality determining measurement outcomes, making it possible for the world to be local. 6:43: Many Worlds interpretation suggests that all outcomes of a measurement happen in separate universes, explaining the appearance of wave-function collapse. 6:57: The challenge for Many Worlds is explaining why observers do not branch with the worlds and see all outcomes. 7:38: 🌍 The Many Worlds interpretation of quantum mechanics suggests that every possible outcome of a measurement exists in a parallel universe. 7:38: The Many Worlds interpretation assumes that observers only experience one outcome, but the reason for this is unclear. 8:06: Each time a quantum particle interacts with another, the universe splits into multiple branches, allowing for all possible outcomes to occur. 8:43: Energy conservation is maintained in the Many Worlds interpretation by assigning probabilities to each branch based on its existence. 9:18: Supporters of Many Worlds argue that it is simpler than the standard interpretation, but it still requires assumptions about measurements and probabilities. 9:43: There are multiple versions of the Many Worlds interpretation, each with slight differences in how they handle branching and measurements. 10:25: To make the Many Worlds interpretation work, additional axioms need to be added, which essentially perform the same function as the collapse postulate in standard quantum mechanics. 10:51: Different interpretations of quantum mechanics, such as QuBism, offer alternative ways to update the wave-function without the collapse postulate. 11:25: 🔍 The Many Worlds interpretation of quantum mechanics is not simpler or more local than the standard interpretation, and it cannot avoid Bell's theorem. 11:25: The Many Worlds interpretation replaces the collapse postulate with other axioms, making it just as non-local as the standard interpretation. 13:07: Physicists have written papers on making Many Worlds local, but this would require introducing hidden variables to transport information locally. 13:21: The EPR paper by Einstein, Podolsky, and Rosen argued that quantum mechanics is incomplete because it lacks a local element of reality. 13:57: Bell's theorem shows that all local theories predict correlations that conflict with observations, which includes the Many Worlds interpretation. 14:28: Many Worlds supporters want to believe their theory is local, but it is not supported by the evidence. 14:39: Many Worlds adherents claim to avoid Bell's theorem by introducing the 'one world' assumption, but this assumption is not hidden and removing it makes the theorem irrelevant. 14:50: Observational fact shows that we only observe one outcome of a measurement, which is the basis for Bell's theorem. 15:20: 🌌 The Many Worlds interpretation of quantum mechanics is neither wrong nor unscientific, but it is as problematic as standard quantum mechanics. 15:20: The Many Worlds interpretation does not introduce anything new and is still non-local. 15:31: The Many Worlds interpretation gives the same results as the standard interpretation when the collapse postulate is replaced with assumptions about branching worlds. 15:47: The existence of other worlds in the Many Worlds interpretation cannot be observed or proven. 16:09: The Many Worlds interpretation is not related to the path integral. 16:21: The paths in the path integral only exist before the measurement, while the branches in the Many Worlds interpretation exist after the measurement. 16:35: The Many Worlds interpretation is as problematic as standard quantum mechanics. 16:50: Believing in the existence of parallel universes is a personal choice as it cannot be confirmed or ruled out. Recap by Tammy AI

This is absolutely convoluted reasoning. Quantum particles (energy perturbations) in a field, definitely have a position at any instance in time…but they are moving at such an unbelievably high velocity that you need to guess their position using a wave function ( because they move like waves). When you measure them, duh…there they are…stopped by the detectors (which also collapses the wave properties of the particle). The sooner we get off the denial train the better!

I watched a debate with Sabine, Penrose, another guy (sorry other guy, didn't remember your name) and one of the String Theory/Many Worlds enthusiasts, from about a year ago. It left me pretty convinced that String Theory/Many Worlds is a dead end - partly because they seem to be making it up as they go along, but mostly because the String Theory guy almost instantly resorted to whataboutery and evasion when challenged. I'm no physicist (but numerate degree educated), but viewing the discussion as a debate I was left with the distinct impression that there is no need for Many Worlds other than to satisfy some mathematical ideas, rather than explaining the 'real' universe.

In the Many Worlds Interpretation, the observers also fork and each observes their own outcomes. Why would an observer see into other worlds? That would suddenly make the 'observer' definition problematic too. Averaging all the parallel words, we get the expected probability distributions that QM gives us.

You briefly touched on Qbism in this video. Would love to see a whole video with just your take on that! It's an interesting shift in perspective, but I don't see how it really affects calculations?

2:16 Sabine talking about too much beer……whilst misspelling “interpretation” cracked me up😂

10:19 I think you mean the many "many worlds interpretation" interpretations.

To believe in the Many Worlds Interpretation of QM, because it can be neither proved nor disproved, even in principle, is tantamount to holding a religious belief - It is an act of faith.

Thanks for the video. My personal version of the many-worlds interpretation is as follows: I accept that it's as non-local as the other non-hidden-variable interpretations of quantum mechanics. And personally, I consider non-local correlation, though not non-local causation, to be perfectly acceptable (as the latter is forbidden by the speed of light, while the former isn't). The only motivation behind it is the idea that the collapse postulate is counterintuitive and that one runs into the thorny issues of, "well, what is an observer?" or "what if a dog uses the measurement device without your knowledge and you never find out directly what the dog measured?". Hence, I replace the collapse postulate with the idea that when you conduct a measurement, instead of the wave-function collapsing, your state becomes entangled with that of the wave-function. Entanglement has already been observed in experiments, with the Bell inequality tests being an example: the "Bell states" that have been observed to violate Bell's theorem (an example of this is a superposition of 2 electrons getting deflected and the same 2 not getting deflected). Let's say an electron is in a superposition of being deflected by a beam-splitter and not being deflected. A measurement would put the system in a superposition of the electron being deflected and the measurement happening accordingly and the electron not being deflected and the measurement happening accordingly. Entanglement of the observer with the system observed would appear to an observer to be a collapse, because there are no physical methods for consciousness of different states to talk to each other. And this solves the thorny issue of "what is an observer?": an observer can be anything that can be entangled with something else. As for the case with the dog: the state becomes a superposition of the electron being deflected and the dog observing it that way and the electron being not deflected and the dog observing it that way, and the probabilities of you measuring this new state is similar to what you'd get from a measuring (or rather, getting entangled with) a superposition of 2 electrons getting deflected and the same 2 electrons not getting deflected. To my understanding, this is similar to Everett's original argument, but I don't claim it's local, in the sense that when you get entangled with a state, you (as a rule) get entangled with everything that you're getting entangled with was already entangled with, no matter how far away it is. (that said, all entanglements must be caused by a local event)

I kind of agree that there are no other universes, Dr. Sabine. Which means I kind of disagree. Let's see if I can make sense. You'd be very familiar with Wick Rotation - The counterclockwise rotation does not have to encompass 360 degrees. It can be divided into single degrees - and even arcseconds. Each arcsecond (or tiny part of it) could correspond to a separate dimension and the total dimensions might make up a temporal multiverse. This is reminiscent of String theory that says particles are composed of one-dimensional objects called strings. My idea is that each string is actually a bit ie a binary digit of 1 or 0 (a pulse of electricity can represent "one" while the absence of a pulse can be "zero"). The temporal multiverse would be united with the one universe by what Albert calls (not called) the Unified Field Theory. Coincidentally, the Internet says a group of binary digits is called a single-dimensional bit string.

Sabine, I don't think so either. Thank you.

My issue with Many World is that if there is one world for every measurable outcome, then then all outcomes must be equally probable because they are each associated with one-and-only-one world. This results in non-unitary probability, and therefore must be false.

Thank you for this complete and correct presentation. You may want to correct the spelling in the slide that starts around 2:10.

FLat earthers doing extra thinking.

I think Sabine is generous to this pseudoscience for no good reason. It's the sociological pressure of Academia. Playing nice with the many world cultists.

The magic of Many Worlds comes from reframing a Measurement as Entanglement. That is the only thing about it I find convincing. I find it incredibly philosophically convenient to think about the wavefunction collapsing as entangling myself with the system I'm measuring. It also helps me to think about the distinction between classical and quantum systems as "systems where the objects are or are not initially entangled." I'm not really a fan of ascribing physical reality to those "extra worlds," as I'm not sure it's sensible to think about "the rest of the wavefunction" once you are entangled with it.

It breaks my heart that so many confuse probability with reality.

Mary Jane Rubinstein has described the many worlds hypothesis as essentially having all of the characteristics of a religious belief system.

In the many-worlds interpretation, the many-worlds interpretation can have infinite names. 😂

I never understood how we go from "anything that can happen does happen" to "anything can happen." Maybe pizza on Mars was an impossibility?

Good video. Lots of food for thought. You mentioned QBism in this video. I'd welcome a video on that interpretation of QM.

Dang, it was cool to consider that the universe easily deals with unfathomable (to us animals) infinity, and that it already had, neatly self-contained in some sort of hypersphere, not only the knowledge of the universe from start to finish (already 😮), but casually also the awesome infinite possibilities of everything that ever could happen, from start to finish; and we were simply metaphorical ants near blindly traversing that, from one possible moment to another, believing we're on a much more simplistic plane. 😳🐜🌌

I am confused. Why does many worlds need something to transport information? If I have a machine that puts an apple in 1 box and an orange in another, when I open a box I instantly know what is in the other box, but has any information been transported? Isn't this what many world's does?

This one is really good. Clarifies and cuts through.

What I find compelling is this: If you have an electron in a superposition of A and B, then you fire another electron at it and it interacts in a way that's affected by the state of the first, it'll then be in a superposition of A* and B*. And the whole system will be in a superposition of |AA*>+|BB*>. I'm not sure if this is the Many Worlds Interpretation, but I suspect that's how measurement works - we don't actually collapse the particle, we just join the superposition. So if we measure an electron in that same superposition, then the electron-physicist system is now in a superposition of |Am(A)>+|BM(B)>. And in that instance, there's no reason to expect the split physicists to have any knowledge of one another - after all, the split realities of the electron don't interact with one another. Is that the Many Worlds Interpretation? Or is it subtlety different?

Hey Sabine, I'm loving the quizwithit experience! It's really quick so it barerly adds to the length of the video. I'd like to offer some feedback: when you complete the quiz, some of the answers are provided to us, but then the page blocks the rest of them with the message: "Join now to uncover your rest quiz results!". Shouldn't it say "Join now to uncover the rest of your quiz resuts!"?

Are mushrooms or LSD involved with the people who came up with this theory?

It is obvious to me that the resolution to this persistent problem is with the "observer". This is often stated to be either a device or a measurement or something similar, but in every case the interpretation reverts back to a human consciousness. Every observation mechanism is itself a collection of particles with eigen states whereas the ultimate/final/backstop observer is a human consciousness that, currently, we cannot define or understand. My interpretation is that every particle is in actuality only ever a wave with its fundamentals defined only by probabilities. There is no collapse in any case or scenario. However, in order to make sense of our existence our consciousness continually decides on the aggregate of all probabilities squared and so constructs a "world" view in real time where there is only ever a probability of one. So, no infinite universes popping up every plank time, no spooky action at a distance or hidden variables. Just a fog of probabilities which we try to make sense of. At the aggregate level, each of our consciousnesses mostly agree on what we observe (trees look like trees to everyone etc). However, as we approach the quantum size our interpretations come up against the perpetual unknowable probabilities, that remain forever just that!. To some extent each of us may decide to observe/create slightly different world views at this scale and perhaps that is an area that can be researched? Lets find out what consciousness is??

"Let not your heart be troubled. In my father's house there are many rooms I will go and make a place for you." I'm going with Universes branching off like cells divide in mitosis or some other micro division which is re-presented in the macro. I feel like there is many things we can draw cues from in viewing the Universe as a fractal. The etymology of words also seems like an important place to look for answers as to how the Universe works. Interpreting the syllables of words to form a sentence I think also gives many amazing clues especially scientific words. Like biology (mode of life the word), phospholipids (light bearer which gives form to the word as what appears), Ribosomes represent the process described in the story of Adam and Eve and the conscious - subconscious reflection like the evening reflects the day or energy radiates out as everything like E equals MC2. Cytoplasm is the word across the waters. 👍⚛️🔯⚕️

I am unconvinced of many worlds. I'd love to see Sabine discuss this with Sean Carroll.

I have seen the beam-splitter description (timestamps 2:50 to 3:12) dozens of times, but I have a big problem. To me, reflection in the beam splitter is an interaction that MUST be considered as a measurement. Everybody making these presentations seems to agree that it is not, but the topic has never been addressed in any reasonable way. WHY does the wave function not collapse at the splitter? Should it not collapse at least for the portion of photons that are reflected?

When I think of the multi-world hypothesis I think of Florida in the winter time. It gets terribly crowded . Traffic moves at a crawl. The number of accidents goes way up. And that's the way the universe ends, not with a whimper but a big bang.

The problem is right there in the title: it includes the word interpretation. So, any physics discussion that involves an interpretation will be just that - a discussion with no hard and fast conclusion.

The Many Worlds theory is a fantastic, robust, and versatile tool for science fiction. This is its primary purpose.

"The major challenge for many worlds is to explain why the thing we call many worlds does not itself branch with those worlds and therefore sees all the outcomes, but somehow randomly only experiences one of those worlds." (7:25) I don't see this as a problem if the observer is branched off with the rest universe into many worlds, but can only observe the world they are in and cannot know if the other worlds exist. So if the observer is Sabine there may be many, perhaps an infinite number of Sabines in many, perhaps an infinite number of worlds. I'm sure we all consider that a delightful prospect. Mind you in some of those worlds Sabine will be not very bright, not very attractive and perpetually grumpy. Not in this world of course.

Whaaaa!! .........no parallel universe , you just broke my heart

ive seen physicists TODAY say they think spacetime is insufficient to explain consciousness and that consciousness is outside spacetime and when we die, our consciousness is freed... sounds suspiciously HEAVENLY if you know what i mean 😂😂😂😂

We can't deny a flying spaghetti monster either. But if we have a Word for universe then it better actually mean universe. One thing to group everything, absolutely everything. Including multiple words. In other words a house with many rooms that also contains it self.

Thank you Sabine 😊 nice to know not all physicists have lost it

The MW interpretation is the reason I can't find my keys when I know I put them in a particular place. In one branch, I put them there, but in my present world I didn't. I've slipped into another world. Give me excuses for a lot of my mishaps.

1:12 "or if it is, youve had too may drinks tonight" xD

In a paralel Universe, paralel universe gives rise to Quantum Mechanics

One thing I've never understood about the MW interpretation. In what sense is the word "world" used? It certainly sounds like a macroscopic concept, but I do not think it can be consistently described. Imagine two quantum systems separated by a space-time interval. When does the branching imposed on "the world" by one event affect the other system? Either the branching is universal and instantaneous (? across infinite distance ? or at least beyond the observable universe ?) or it propagates outward, say, at c. In either case every locality is continually being branched even when no branching event (?) takes place. Or, are we to supposed that systems that have not experienced the qualifying transition are simultaneously present in gazillions of worlds? I just do not know how 'the world' (or 'the cosmos' or ??) can suddenly be introduced at this level when it has not played any role in the theory previously. Color me unconvinced that the MW interpretation is not gobbledygook at the philosophical level.

I like how she makes up the word "update" for wave function collapse to make it sound less ridiculous and how she still pines for hidden variable theories after Bell's inequalities experiments.

I don't think the creator is worried that we will succeed in managing to reverse engineer his work anytime soon. 😅

Im not a physicist, but an IT guy. Hearing all this makes me think of the nyquist theorem (aliasing when measuring signals). It states that you must measure at least twice as frequently as the highest frequency of signal you are trying to measure so that you can reconstruct it. Is it possible we aren't measuring frequently enough and therefore can't reconstruct the wave function?