ha 😅

Chaotic, you might say.

Psigh...

Don't worry pal, you can posticipate it to sunday

It's okay, you can leave it as an exercise to the reader

I came here just to read that comment! …misunderstood. Poor thing. Lol!

Richard Fynmann told us that nobody understands Quantum Mechanics... it is possible, but I don't know, Sabine could be smarter than him. But in any case RF was smarter than most of us!!!

Yea, she is a legend. I really love how she separates the unnecessary, speculative and brings us back to what physics is - a strict science(after maybe math, he-he). Today pop sci-fi blended physics and speculation with religion, mysticism and other bullshit which has no place in science whatsoever. Physics is a SCIENCE., and should we should employ scientific methods - avoiding any speculation when possible :)

Came to the comments to say the same thing, I was still laughing but saw you beat me to it.

@@bluesque9687 No Sabine saying nobody understands QM so she agrees with Fynmann.

You have no idea what you are talking about…. 😂

QM doesn't have a problem with chaotic systems if the wave function collapse is taken into account. The blurry blob that would describe an observer and the observed system hides correlations that reproduce the classical physics of chaotic systems. The only problem is that we don't have a theoretical method to single out the classical recordings of the object trajectory within the wave function : we know empirically how it should look like and we take the decomposition accordingly. After all we know that we can only measure dead or alive cats with our senses, not superpositions of dead and alive. The true limit of the universal wave function concept is that we don't know how to make general relativity work with quantum physics.

In the many-worlds interpretation of this problem, there is... no problem. Literally every possible outcome actually happens. In the case of Hyperion, it takes all possible paths, every way it can orbit, it will orbit, simultaneously. The reason us, conscious observers, only see one path is because we can only garner information of a single path. We can never know what all other paths are doing and how they are evolving because there is no mechanism to transfer information between those 'worlds'. And the 'wave function of the universe' is where all those paths are 'written on' so to speak. Unfortunately, because of that very fact, the many-worlds theory is literally unprovable.

>>Wave Functions of the Universe are Just Dumb Math Errors

@@A_Saddler I'm not convinced many worlds is unprovable just because we can't directly interact with other branches of the wavefunction. In fact, isn't the point of this video evidence for many worlds by ruling out unphysical wavefunction collapse? (I don't see how wavefunction collapse can be physical since it's nonlocal, which thanks to the relativity of simultaneously means it actually rewrites history.)

@@A_Saddler To clarify, I'm saying that the collapse has to be instantaneous in every reference frame. That actually implies it has to propagate outward at the speed of light moving backwards in time. On a spacetime diagram, the collapse would happen in the future and throughout the entire elsewhere. The past light cone is the only place where the wavefunction is not collapsed. That seems pretty unphysical to me.

Yes, my religious feelings have been hurt as well. Where is the trigger warning?

Actually it's another episode of the eternal QM sitcom:"Kopenhagen vs. Many Worlds". And as usual for most sitcoms it's always the same joke presented to you in different disguises/incarnations overdubbed with an artifical laugh track.

Doubt. I'm nearly sure, is sacred.

the real problem of QM is that its not Physics. Its hyperbole, and its illusionary. A fantasy of SciFi. Its just playing groundless math exactly like the other fantasy pseudo science, Special and General Relativity.

Unfortunately Hossenfelder is not reading the comments, which is no wonder given that there are thousands of them. Now I cannot contribute anything to what you write, but what I think is rather clear is this: It's not only that nobody who thinks they understand QM really understands it, it seems that physicists do not really understand why it is that they don't understand QM. So I would like to suggest not so much a solution but a way out: Assume that reality is such that it works as if we lived in a computer simulation. Then o ur observations are caused by that computer calculating the Schroendinger equation and then randomly picking which conscious observations to produce for us. Voila, nothing there not to understand related with QM per se. No mysteries, in the same way that a student cannot resort to mystery to justify their failure to give the right answer to an exercise. In short reality may be such that there is nothing in QM to "understand" in the way physicists like Hossenfelder use the term. I say nature tells us as clearly as it gets that there is no physical reality out there, but physicists insist there must be because, as they believe, that's what physics does: study physical reality. But what physics actually does is to describe the mathematical order present in physical phenomena. Or more precisely the statistical order present in physical phenomena - which is all that is needed to make predictions and build machines. Everything else beyond that is make-believe. Incidentally I am not saying something new, I am just using the computer simulation argument to illustrate it. So about a century ago Bohr (or perhaps somebody in his group) said "There is no quantum world. There is only an abstract quantum-physical description. It is wrong to think that the task of physics is to find out how nature is." In metaphysical philosophy this view is called physical anti-realism.

@@DianelosGeorgoudis 'we are living in a simulation, its all imaginary", is just utter nonsense. its the material you ponder when planing your next SciFi movie plot. Nothing about it is actual Science, and not a hint of Physics in there. But you were right to suggest that " nobody who thinks they understand QM really understands it, it seems that physicists do not really understand why it is that they don't understand QM." And the solution is that nothing about QM or its quackery cousins, General and Special Relativity, is rational logical science. , so the answer is simply to realize that we have been sold a pack of utter rubbish masquerading as real Science. High time we got back to actual Physics, and put nonsense in the trash bin.

Ok boomer

@@MrPDTaylor ah, wise words from some idiot that is normally watching tictok. So we should listen to him. Meanwhile the BS of Einstein is still taught as if it were true to the actual boomers, so there is little hope.

It's in no one's interest to disprove quantum mechanics which is why the downsides are almost never shown in public facing media. People want to hear fantastical stories about parallel universes that are exciting, not that boring classic Newtonian determinism is how the universe actually works.

@@joey199412 Nah it's probably caused by dark matter...Whenever the math don't work it's always dark matter 🙄

​@@joey199412 Newtonian physics isn't correct either. There are plenty of experiments that contradict it, in both quantum physics and relativity.

@@davidknipe4113 Yep even Sabine falls to this. The fact that the Relativity Replacements for Newtonian physics are so nasty(hard) math wise means people avoid them and Newtonian still gives a close enough often enough it still in use.

@@RedRocket4000 Relativity corrections are essential to any orbital calculation and to your GPS. The gravitational and special relativity corrections to GPS data are similar in size and would double the error about every millionth of a second without the corrections.

Dark matter /energy paradox SOLVED m.ukposts.info/have/v-deo/koF_i4yImmukr30.html

thats sad.

idk, from what I’ve seen most of the physicists know what the problems of QM and other theories are and don’t accept them as laws.

Ssbine Hossenfelder is a strange way of spelling Eric Weinstein.

@@rotorblade9508 I have read or heard several times QM does not apply above the sub atomic level. Thus some folk clearly are aware of the problem. I am aware that they want QM to apply above the subatomic level but efforts to show that keep failing. I have already read several times QM is incomplete. And the fact that there is no accepted version of QM means it's quite incomplete. I in particular get annoyed when someone tries to say something in Relativity is wrong based on QM and I'm going Relativity has been proven correct experimentally every time while we don't even have an agree version of QM so stop using the more incomplete idea to disprove Relativity which only breaks down in conditions we might never be able to measure or in other words for any reference frame we actually deal with Relativity is totally correct. Some parts of QM are very well tested and QM has had a great deal more practical uses after all it deals with the small while the large were we need relativity does not effect our daily lives as much. But practical use does not stand as a proof of superiority of a system especially one we don't even have one version of yet.

I wish she would take a look at my theory and then started questioning it.

We have not existed with technology long enough yet.

She´s good in that, I love it too!

There is a "simple" solution to the problem: Einstein wasn't right and time and space are in fact absolute. Of course we still need to take time dilation and length contraction into account to remain in agreement with observations like Michelson-Moorley, but Lorenz showed that this is totally possible. The problems starts when we consider Einsteins proposal that there is no "ether" and also no absolute time and space. Because of this we have the problems with understanding QM. Buf if Einstein was wrong and "spacetime" is just a convenient mathematical tool instead of physical reality, then the problems with QM goes away, because it's no problem anymore to have the wave-function collapse happen everywhere in the universe at the same time as a real physical process. Absolute time has some other interesting consequences. For example the event horizon of black holes would become a real physical boundary - which would in turn solve the problem of the singularity (which wouldn't exists anymore because space would simply end at the horizon). Einsteins ideas were totally plausible at the time he formulated them. But then there was no QM, no QFT and no Big Bang back then. And considering those, Einsteins ideas don't look as plausible anymore. For example QFT brought the "ether" back which Einstein got rid off with the SRT (of course the ether needs to be Lorenz invariant, but that's not really problem). So maybe we should also start to question if the picture of Einsteins concept of spacetime is still a good concept.

@@Kah7654 wow! Explain time dilation. You know it's incorporated into GPS satellite technology, otherwise they would be wrong by about 50 feet after a week, and constantly getting worse. While you're at it, explain gravitational waves, black holes and the precession of Mercury's orbit.

@@Kah7654from where did you learn qft talks about ether??

@@henryD9363 Time dilation was explained by Lorzenz simply by saying that moving inside the "ether" slows down the local ("proper") time of the moving object. To explain Michelson-Moreley we also need length contraction, but this can be explained if we apply time dilation to Maxwells equations which in turn would "squeeze" moving objects. Einstein used all this work of Lorenz (including his "Lorenz transformation") for SR. He just said that there is no real time-dilation/length contraction but those are not "real" but just effects of the geometry of spacetime. At this time Einstein clearly had a point because by applying Ockhams razor an unobservable ether should go away. But in the light of later developements this doesn't holds its validity anymore (IMO).

@@enkaramessi10 The "Quantum Fields" ot QFT are very similar to the comcept of the ether, they just aren't called it that way. Of couse quantum fields needs to obey Lorenz invariance to agree with observations, but that's not very difficult to obtain. Using Minkowski space to describe those things makes it much easier to work with them. But that doesn't mean that space really is a Minkowski space, it may just be a quite concenient mathematical tool for a different physical reality.

Do you hear the voices too?!!

Computability is a strict subset of provability. The human brain will discover new things in math forever.

@@cristianm7097 Don't get hung up on the semantics: Godel's theorem are limitations of PROVABILITY not COMPUTABILITY.

@@USABarsa Exactly. The OP mentioned "computational limitations" , that's why I wanted to emphasise that provability goes beyond computability and mathematicians can discover new things in math without being limited by what a Turing machine can do.

Godel is about the limitation of a formal system. But doing physics, or even math, is much more than just walking within a formal system. They are more of a refactoring of the observed. And the observed themselves always form a consistent total. What godel says is one can always sneak in with a self-referential sentence in a formal system that has something arithmetic-like. This self referential sentence can not be reduced to axioms because to know/prove its truth value will require already know such truth value in advance. Such formal phenomenon can not occur in physics because there will never be a measurement of infinity. There can’t be such things as infinite recursion or stuffs like these. What I mean is that the problems in physics are categorically different from problems presented by Godel.

Yes, good point indeed. As you say, we don't actually know how gravity works on the quantum level, and some physicists (notably Roger Penrose) think that indeed it's got something to do with the measurement problem.

There's a Nobel prize in there somewhere, I reckon!

@@SabineHossenfelder I suspect that gravity is an interaction that happens somewhere within the chaos 🙂

@@polarper8165 I suspect spacetime is an emerging phenomenon from quantum interactions/measurements/entanglements and gravity is just a property of the shape of the resulting spacetime. The fact that spacetime sort of 'collapses' in a black hole indicates that it can't be anything fundamental. The problem with QM at the moment seems to me that it's written down in field equations which describe QM variables depending on space and time: this is the wrong way around if spacetime isn't fundamental. What you want is equations of some variables that have spacetime as output. I believe Stephen Wolfram is e.g. trying this with his hyper graph approach. Not sure if that is any good, but I like the approach of not basing your equations on spacetime. Imho there is no way to get to quantum gravity if you stick to quantum wave functions that are functions of space and time.

@@JaapVersteegh Wow you really seem to know your stuff.

@Michael Lochlann Unpredictably so?

But the moon is still an track, a bit of chaos makes it so interesting that it´s worth a vid by Sabine, all the best

That's right, sorry, and of course there are other examples. I was referring to differential equations.

How exactly is x(n+1)=2*x(n) chaotic?

But surely that recursion is only chaotic if you take the residue modulo something. And that is NOT a linear operation.

I was thinking the same thing, but then I remembered that "linear" in this context does not mean the same as "all polynomials are degree 1". stepwise functions like that are nonlinear in the time domain.

To be as nitpicky as you are, it doesn't even make sense to say your example is linear: either you consider it defined on the circle, or on the unit segment. Neither manifold is [the manifold obviously associated to] a [real finite dimensional] vector space in a way that you could talk about linearity.

1 thing actually existing in 2 places at the same time doesnt seem weird to you?

It’s weird to think that the schrodinger equation is linear but the actual action of solving it for a particular metric of a system non-linearizes it rendering it both impossible to explain and the reason for chaos itself. Then if quantum mechanics has a gravitational parameter then time dilation itself has a quantum bit of information and the graviton is both the quantum of time and space. So in order for quantum particles to collapse into one state, they’d have to interact with themselves across themselves disregarding the Higgs mechanism to relay the information from one point in space to another. Perhaps every quantum particle uses quantum tunneling to collapse at the same time as its entangled pair.

Well, this is not a correct conclusion. Schrödinger equation operates on wave function in Hilbert space. More natural and fully equivalent is the Heisenberg picture, which gives you equations of motion for observables. If the classical system is non-linear, so are the non-linear quantum equations for observables.

@@jirihladky259 isn’t every quantum wave function linear in its construction but non linear in its collapse? Wouldn’t that mean there’s some non linear action that acts across all entangled cousins of the measured particle to cause it to pick a state upon measurement?

@@dominicellis1867 The classical non-linear system is also non-linear in QM. Schrödinger picture is linear because it's formulated in the Hilbert space. But the system itself and the observables still remain the non-linear.

This video is literally 🤯

Agreed. I also wonder why she didn't talk about the n-body problem given chaos also emerges in that case, starting with 3 body problems

I'm confused tbh. I thought the linearity of the PDE manifests itself in the linearity of solutions: 2 solution functions added are still a solution (even if themselves are nonlinear, which is often the case for eigenfunctions). But classical mechanics can have anything in the force term, and thus nonlinear dynamics deals with solutions that cannot be added together to get another one. And I think this is what creates chaos.

Thank God, finally comments that actually challenge Hossenfelder‘s claims.

I don't believe would this introduce chaos into the Schrodinger equation. Since the Hamiltonian is a linear operator, and it is a bounded linear operator over the domain of finite energy initial conditions, it is a continuous operator. Perturbed solutions should lie in a neighborhood of the unperturbed solutions, i.e. no chaos.

@@mihaifrancu736 Linearity of solutions means that the space of solutions is an affine space not that the solutions are linear functions.

The chaos is not caused by QM. If you apply Heisenberg's uncertainty principle for angular momentum, which states uncertainty in angular momentum * uncertainty in angular position >/= hbar/2, you see that because hbar/2 is so small (on the order of 10^-34) any uncertainty in Hyperion's angular momentum is too small to have a macroscopic influence we can observe.

@@thevikifalcon7670 but the uncertainty principle is a lower bound, so I dont see the problem.

My understanding is that even if you speculate about a perfect model for the system which accounts for literally everything, we already know that it wouldn't describe the chaotic motion accurately because at the end of the day the model is being passed through a linear equation, which is the part that is incapable of producing the chaotic motion over longer time periods, regardless of the inputs.

​@@rantingrodent416 Chaos can be an emergent property of systems that cannot be individually chaotic if you have enough of them interacting, so I'm really not sure what this video is trying to say? Over the timescales we observe the moon there are many tiny linear interactions that combine into non-linear forces, like the light from the sun disappearing as it moves behind the planet. If you had perfect knowledge of the system and infinite computation then it might technically not be mathematically chaotic, but that's not a definition of chaos you would apply to physical systems.

One thing to note however is that the Uncertainty Principle means that from the standpoint of any possible observer, QM is random. You could only make it deterministic if you perfectly knew the initial state - and that is impossible. So even if the rules of the system are deterministic, the system itself remains non-deterministic due to this uncertainty of state. Only an imaginary system in which you predetermine the state could ever be made to behave deterministically - never a real one.

Schrödinger's Equation is totally deterministic but the quantum wave function in it can only be known by its amplitude, not its phase in experiments i. e. measurements. If we try to measure a quantum wave function by having it interact with another quantum wave function, we still can't know what we'll get for sure because that other quantum wave functions has a phase that we don't know.

There's *NO* way to measure anything without having it interact with a quantum wave function and observing the amplitude of the result.

@@solconcordia4315 I don't think that's what I was talking about. When you measure, you don't get the amplitude of the wavefunction. You get a definite value selected from the wavefunction. This is unrelated to phase and its unobservability.

Each measurement yields an eigenvalue of the system. The eigenvalues are all discrete for a *confined* system but the mean of the probability distribution of the repeatedly measured values is proportional to the squared-amplitude of the wave function. That's what I mean by "measuring the amplitude" of the wave function. We don't know the phase of the wave function because the squared-amplitude related to the probability of obtaining that particular eigenvalue is defined using the wave function multiplied by its own *complex conjugate* so the phase disappears. A wave function and its complex conjugate can have different (equal and opposite in sign) phases but identical squared-amplitude. Even in *purely* classical physics, chaos exists so I wasn't surprised that there may be systems subjected to chaos. Saturn with its rings is a planetary-moon system still forming so there is much dust there to introduce chaos to Hyperion's axial orientation. I do harbor some doubt about Schrödinger's Equation regarding the angular momentum of the ground-state electron of a hydrogen atom.

Life is a role of the dice. Preordained or not, God was there. Sucked to be Job. Small pox and all, that was a righteous man! I could only hope to attain his standards. I flunked he never even looked at other women! 🙈😊. I’m always looking at women. Sabinah I’m guilty... minerals and a rag. The numbers and her beautiful disposition.

@@softan give it three or four days. As of everything, I never get credit for...

The observation is what caused the wave function to collapse.

@@peterjackson5539 “The wave function caused the collapse?” “Beauty is in the eyes of the beholder.” Gravity has a frequency, The spectrum fed into AI?” Making a visualization? Sabinah with her long hair. She always makes her clothes look good. Chaos. Into Light 💡? 🤗

@@djoswald9128 So you believe that the universe exists whether a conscious being is observing it or not? That's fully up for debate, definitely not settled science. en.m.wikipedia.org/wiki/Copenhagen_interpretation#:~:text=Prominent%20physicists%20associated%20with%20Copenhagen,had%20overwhelming%20acceptance%20among%20physicists.

Dark matter /energy paradox SOLVED m.ukposts.info/have/v-deo/koF_i4yImmukr30.html

Yes, I was also wondering about that :p Like what do the wave function vector actually contain ? Cause if it contains say psi = [x,y,z, x^2, y^2, z^2] (where xyz are classic 3d coord.), then a linear equation on psi would actually be nonlinear in x,y,z (similar to the kernel trick in ML, BTW if anyone knows connections with the kernel trick and QM, send references: that would help me a lot understand QM (cause I’m more familiar with the kernel trick in ML) :D)

Thank you from the entire team!

Ambiguous pronoun "this." Do you mean Sabine's video blew your mind, or what you studied blew your mind?

@@brothermine2292 yes

@@nziom : Which one of the two?

​@@brothermine2292 And who is this mysterious "we?"

@@ericsandmeyer : The ""we" is ambiguous because it's anonymous, but is neither mysterious nor of interest (to me). You should re-address your question to the person who wrote the "we" if you think the answer would be of interest to someone.

Yes, but many of the claims she makes are false. Quantum chaos exists and it has been observed experimentally. There was a lot of work on it in the late 1980s and early 1990s, if I remember correctly.

You're actually right, being chaotic isn't related to being non-linear, Sabine is wrong here. The reason why Hamiltonian mechanics allows for chaos is that the volume in phase space never changes (Liouville's theorem), so the initial uncertainty you had about the system always remains the same, except it gets stretched in really complicated patterns all over the phase space, so you can't really draw a simple boundary about it. Imagine taking a ball of yarn and unwinding it all over the room: even though there is as much yarn as before, you now can't really give a single "position" for all of it, it's entangled in complicated ways. The reason why this is a problem for quantum mechanics is that the wavefunction actually spreads out in phase space (unlike in classical physics), so in the end it just becomes a homogeneous blob all over it, and it doesn't really exhibit much chaotic behaviour as a whole.

@@silentobserver3433 +

Yes, this is a good point. The fact that the phase space distribution or the density matrix evolves linearly means nothing for whether the system is chaotic. What matters (roughly) is whether the standard deviation of a sharply defined distribution eventually grows to the size of the accessible phase space. And this is clearly true in classical and quantum chaotic systems.

The equation rho' = - {rho,H} isn't linear in any sense of the term, you have no way to "superpose" solution. The equation may look that way, but if you try to add two solutions and unpack what {rho,H} means you'll see it is not.

I am not 100% on what you guys are saying, but I have a sense. Does this effect the big picture of what she is saying, or is this more of a pedantic tangent or correction?

Yes, and we cannot measure "has the wave-function collapsed?" -- we can only measure position, momentum, etc. and INFER that surely the wave-function must have collapsed. Another seldom-understood point is that, because of the symmetry between position and momentum, a "collapse" of position is really a change from a state of indefinite position (and possibly definite momentum) to a state of definite position (and indefinite momentum) -- which is now ready to be "collapsed" by a momentum measurement into a state of definite momentum (and indefinite position.) Max Born, considering only position measurements without due regard to the position/momentum symmetries involved, gave use the idea that the transition is from "unreal" to "real" or from "less real" to "more real." This is false. It's just a transition from "less definite" to "more definite" IN ONE TYPE OF VARIABLE, position or momentum or whatever.

IDK … but Gravity is not a force. The concept of causality or the structure of space time being chaotic so close to the earth is a bit scary.

I am thinking earth and moon’s speed (slow down or speed up) at the point when moon, earth and sun are in line. Are they same as Hyperion with Titan and Saturn?

@@thomasreedy4751 Lots of current QM ideas insist the Gravity is a force. As Matt on Space Time stated Gravity not being a force going to make a lot of people sad. I'm with you Gravity in Relativity is an effect not a force and this is true down to as small as we can measure which is at sub atomic level but not very sub atomic. Thus only the Relativistic minority in QM researchers who are trying to make QM comply instead of defeat Relativity are likely on the right path.

Einstein said his greatest mistake was introducing a non-zero "cosmological constant" into general relativity (to explain the steady state universe he believed in). Perhaps his actual greatest mistake was dismissing the deBroglie-Bohm deterministic quantum theory as too ugly. Or perhaps his dismissal of "spooky action at a distance" (also known as nonlocality).

I'm concerned that society is a balancing house of cards, any shake could topple the whole thing.

In my opinion a bit of there is little work in Relativity and lots of work in QM available leading to a natural QM bias.

she neither proved nor disproved it. All she said was that we dont understand how it works. Newsflash!

@@googleyoutubechannel8554 en.wikipedia.org/wiki/Applications_of_quantum_mechanics#:~:text=Important%20applications%20of%20quantum%20theory,as%20magnetic%20resonance%20imaging%20and

She's willing to challenge assumptions and theories... Until those theories are her own. Don't let her kid you, she's just as flawed as the rest

Yeah, objective collapse is pretty much at odds with many worlds in every way lol

@@anon6514 I don’t think it is. You could alter the initial conditions a little bit and then the objective collapse happens differently, at a different point, with a probability distribution according to the Born rule. One could imagine that there are different universes where the wave function collapses physically, where every universe has a (slightly) different initial condition. You could tune the distribution of universes in such a way that the points at which the wave function collapses still follows the Born rule. Objective collapse and many worlds are not mutually exclusive. I hope you know what I mean.

@@patatje6974 I get what you mean, but if a similar but different process happens in each of the universes, then there's potentially no need to invoke the existence of other universes. It could be explained entirely with the physical process observed in this universe. But it's one of those things where if we can somehow demonstrate other universes exist via the process in objective collapse, then we'd probably argue that what we observed was actually in this universe... because we observed it.

@@anon6514 yep, but I think it will be very difficult to prove objective collapse. Who knows.

It has been stated our brains are not designed to do this type of thinking thus it's rough on them.

I think Greg Lake summed it up: "As I reach out, it slips away"!

Sounds like "many worlds" as popularized by Sean Carroll. Instead of collapsing the wave function, just consider the observer as part of the system. Bohr believed instead that quantum systems entangle everything they encounter, in the entire universe, except humans... Yes, WE *collapse* the wave function! The hubris!

It appears that interaction causes the wavefunction to resolve, and any process of observation much pass through a chain of one or more such interactions. So the observer would through one or more of these steps become entangled with the observed quantum system. Of course the wavefunction collapses along they way are all happening regardless of who's watching, but the watcher will/must be part of that process if they wish to be able to detect any information about it.

@@Vastin AKA objective collapse theory. Makes sense enough for me!

@chrslb Yes. The founding fathers of both quantum mechanics and relativity were pre-computer continuum-math devotees, and thus had almost no appreciation for the severe precision limits that finite local energy imposes on both the physical world and our models of that world. This caused a century of perplexity in which infinities popped up constantly in our math due to inattention and indifference to this issue. For example, the simplest definition of quantum mechanics is that it is the limit of resolution possible given the finite energy resources of our material world. 2022-05-28.09.42 EDT Sat

@@TerryBollinger Thank you! Are you talking about some kind of finite computation model of reality? It would be interesting to hear more about this. I wonder if naively this means that our world behaves as if it were simulated on a computer.

@Alfred Wedmore I would agree that a chaotic system cannot be simulated. But if you do try to simulate one (see for example simulations of the Lorenz system) I think it's still impossible to predict its behavior in practice if there is any noise at all, because the noise still gets amplified by the chaotic system.

@@chrslbIt's a finite computation model, but the computer and the software are one and the same, with the behaviors we call physics emerging as the parts interact and constrain each other. Strandbeests are a better analogy: ukposts.info/have/v-deo/hJWoint9aXiQ0YE.html

>>The Strandbeest Universe

She mentioned decoherence and macroscopic entanglement, which are phenomenon of Everett's MWI. In traditional QM a dust grain can't entangle with Hyperion since neither are quantum objects

Exactly, but Sabine does not subscribe to the MWI. There's no persuading her; I've tried.

@@Tehom1 I'm not suggesting she subscribe to it, but the video covers various things she doesn't agree with and why, I just thought it would be nice if she covered the interpretation that explains all the inconsistencies that she's pointing out.

when we measure the speed of something we usually measure something that’s made of particles which travel in a certain way so basically particles may have the speed limit as c. However some experiments make us think there can be something other that particles that can go faster than like and this is the update of the physical corespondent of the wavefunction that is done instantly and even backwards in time (delayed choice quantum eraser). So this update would happen but not as particles going from one place to another. Anyway Special Relativity doesn’t allow anything to go ftl. It’s also not possible to send information ftl by means of entanglement between particles at large distances between each other even if the collapse was physical so some may think it’s physical.

So, the interesting thing is, the wave front for any interaction has *already* propagated at the speed of light. The weird bit is when a photon gets to decide which planet it actually hit across a wave front 20ly across - that wavefront expanded to 20ly at the speed of light, but it did so in an entire cone of possible directions at once, until it finally actually decides which thing out there it actually hit - If anything. Given that the mean free path in intergalatic space is probably longer than the width of the visible universe, in many cases it flies out into the depths of endless space and never hits anything again. I kind of wonder if it even technically exists any more once the wavefront for these photons passes outside the particle horizon of any possible interaction in our universe?

@Michael Lochlann So far it seems that entanglement resolution is for all intents and purposes instantaneous - but if physicists are correct in their statement that there is no way for *information* to be conveyed via this instant phenomenon, then there is no paradoxical conflict with special relativity - it cannot invert cause and effect even if it is an FTL phenomenon.

Curiously enough, after making the video I ended up writing a paper about exactly that! Should be out in a month or two.

@@SabineHossenfelder I can't wait to read it!

@@SabineHossenfelder Ich bin aufgeregt!

@@SabineHossenfelder I assume it has occurred to physicists that if time is emergent, then quantum systems do not evolve in time, so whatever DOES make them evolve gets to the heart of the measurement problem? Considering wave functions, the resolution of probability is what is happening. So time can be seen as appearing to evolve based on probability continually resolving. Still doesn't tell you WHY probability is resolving, but if time is emergent...all you have is the wave function and the probability for all of its resolutions. The "physical" process can simply be a reflection that once a wave function possesses all variables pertaining to a single moment of resolution, what that resolution will be is already a done deal. What is nature waiting for? The systems are not evolving in time, the evolution comes from the system themselves, so the march into the future is only dependent on the isolation of the variables pertaining to what the future will be in this view.

Is chaos real? Or it is just a limitation of our computers or understanding?

I think David Deutsch's variant of Many Worlds makes more sense. Instead of branching, there already were an infinite number of (parallel) universes. A fraction of the universes are configured with the identical experiment, and the quantum probabilities correspond to the approximate fraction of that fraction that have the particular outcome. I'm not a fan of either Everett's MWI or Deutsch's variant... they postulate an extravagant number of universes in order to hang onto the locality assumption, and since space isn't well-understood it makes more sense to me to relax the locality assumption.

@@brothermine2292 MWI gets so misrepresented always... The branches are never an assumption of the model, and neither are parrallel universes, they were derived by math simply by removing collapse postulate from QM. If you don't interact with the system, it does not collapse, and it results in a very complicated superposition of states, with every particle entangled to every other particle in very complicated way. However, you can represent any superposition as a sum of some parts that are so different from each other that they almost don't interact (wavefunctions have to overlap to interact with each other, and if there's no overlap - there's no interaction). Therefore every such complicated superposition can be viewed simply as a sum of some separate parts (call them "worlds") that can be viewed separately, and each such part has its own amplitude, i.e. you can calculate probability of the system being in that particular part of the wavefunction. Now consider the whole universe a single system, with nothing else interacting with it, so it does not collapse. It is just a very-very-very complicated superposition of many possible states, and such superposition can be viewed as an infinite sum of different "worlds", that are just parts of the wavefunction that don't interact with each other because they don't overlap. Since we're also part of the universe, we're also in a superposition of states, also represented as a sum of "worlds", but we're entangled with the rest of the universe, so each version of us only sees the corresponding version of the universe, because it has been entangled only with that version. So nothing really branches, and the whole "many worlds" idea is simply an approximation, because we can't really comprehend the whole insanely complicated universe wavefunction, so we split it into a sum of more reasonable-looking parts (even though the split is never exact). The only problem with this is that our consciousness, or soul, or whatever actually experiences the universe, only experiences one world for some reason, but that's a question for consciousness, not QM. As for math of QM, it really is the same in the MWI. Specifically, we can have a superposition state of two particles, which is |Ψ⟩ = 1/√2 ( |↑↓⟩ + |↓↑⟩) = 1/√2 ( |↑⟩×|↓⟩ + |↓⟩×|↑⟩), which is a sum of two parts, |↑↓⟩ and |↓↑⟩, each with amplitude 1/√2 and probability 1/2. If we know that the interactions don't mix those up, or mix them only slightly, we can just say that they're two separate worlds, |↑↓⟩ world and |↓↑⟩ world, and talk about how other particles might interact with each of them (instead of interacting with the whole sum). That's really all there is to MWI, no branches, no parallel universes, just a sum of wavefunction parts.

@@silentobserver3433 : Okay, to be precise, the worlds are derived in MWI as you say, not a postulate of MWI. In Deutsch's variant, however, the infinity of universes appears to be a postulate. But regardless, there appear to be multiple versions of the experimenter who observe different results. I think it's inadequate to say this is a problem for consciousness theory rather than for MWI.

@@brothermine2292 True. It is basically the same problem as the collapse - somehow from somewhere Born statistics appears, and it's either directly postulated inside the collapse definition, or in the way observer decides which world to go to in MWI. It's just that in MWI this is at least somehow related to consciousness/experiencing the world, since that's the only thing that exists in a single world, according to our experiences. However, at least MWI doesn't have an instanteneous, non-local, non-linear, non-differentiable, informally described law of evolution that is the collapse postulate.