They usually claim and state a lot, but when one takes the time to think and verify, one finds a contradiction, logical fellacy or incompletedness... like the makers of those videos don't know themselves what is actually meant and why it worked that way. When I looked at the Bell's theorem discussion the last time, it started out by: - Einstein claiming hidden variables - another guy saying hidden variables would violate blahbla - third guy proving blahbla is violated - fourth guy saying violation proves Einsteins claim wrong. I invested a lot of time determining what was wrong and came to the same conclsuion Sabine did.
@@skeltek7487erhaps this difficulty that we're experiencing is the same as physicists lol. I bet even they are basically believing what they want to believe at this point. Simply because quantum mechanics is such a complete mystery. So much theories postulated but over time, only a few of them are actually proven.
I usually only understand about 50% of deep physics, but I like that your videos help nudge that percentage up to 50.1% with a 0.1% error margin either way.
I kind of half understand about 5% but only if there are diagrams. But I keep coming back because her videos are the wildest thing you can experience this side of the Controlled Substances Act!
This is self-deception. If you offer any listener here the most elementary problem, not one of them will even find the right way to solve it, let alone the solution as such.
For all the math people out there, locality is sort of the physics version of the Intermediate Value Theorem, which states that for a continuous graph, if it passes through point A and B with coordinates (x1, y1) and (x2, y2), respectively, the graph has to go through every point in between. So locality is if the the graph is continuous and non-locality is if the graph is non-continuous, meaning it doesn’t have to pass through any of the points in between
And yet a ‘continuous’ spacetime is only macroscopically valid, so we might need a discrete definition of local causality as well. However, it might be necessarily probabilistic, such as ‘nature is most likely to act from A to B along the path of least edges’.
Yes! So if QM ppl things reality is non-local, then the first thing they shud do is to reproduce entire QM without calculus. Or, they shud shut up about shut up and calculate.
@@anywallsocket Only if you assume Relativity is wrong and Quantum Physics is right. Space-Time might be continuous and there might be Hidden Variables, and the lumpiness of Quantum Physics is a flaw, a limitation. If my friend, Prof Tako, is right, we might have a new theorem on this. It's a modification of Bell's Theorem, called...
@@anywallsocketo one knows this. Some Quantum Physicists only erroniously claim this. Yet they never managed to demonstrate "non-continuous" nature of space-time. Rather the fact that the speed of light is same for all wavelength and actually for all massless particle is a rather strong evidence that space-time is most likely continous.
Quantum mechanics and Artificial Intelligence is being taught to the general public by journalists. It's no wonder it seems like no one understands either.
I did my master's degree on artificial neural networks. Believe me when I say that computer scientists don't understand AI either. (I'm very serious; we have quite a limited grasp of the emergent processes that occur within deep neural networks, such that interpreting them is an entire field of academic study.)
This was some of your best work Sabine! Apparently making peoples brains hurt and making them laugh at the same time is just what science education needs. Why the Profs thought they could be dry as an old biscuit and expect people to listen has always been beyond me?? I would've gone to your lectures instead of reading the book. That's a big statement as the book has all the knowledge you need and doesn't expect you to get out of bed or even wear pants!
Haha there should be a No-Bell prize in the name of Bell for negative results to promote and give recognition to all hard work in experimental science and research, not only "lucky results"
All need a secret before u can experience Jesus healing energy. The Illuminati aka fallen angels aliens NASA what ever you want to call them in there flying tin cans. Can't get out of lower orbit because of the vacuum. Universe is only 77 thousand SQ miles big breathable air through out space angels have to breath. Mars is only 250 miles away sun an moon are much closer an only a acre big. Heaven is on Mars moon that's what all the thrusters are for space x Star ship try to punch through the vacuum and destroy Mars moon heaven. I cleaned out hell left the light's on so no use for hell. I ripped the soul out the devil after he went dragon just to make it a fair fight. Now souls can be destroyed. True compassion for your fellow man is the only way. Now all are allowed black an white sheep to experience Jesus healing energy all old aches and pains will be washed away takes 30 minutes best to relax and shut yr eyes. Or I'm lying an u won't feel a thing
I've been physics-curious all my life but didn't pursue it in college because I couldn't understand certain principals. Sabine's animation of the two envelopes and the information within _finally_ made this concept click for me. I kept trying to find some way for the other envelope to "know" instantaneously what the opened one contained. Science writers should watch this video
I'm really interested in physics, but whenever I watch some videos like these it feels like my brain is melting sometimes and I have to rewatch parts, am I just not made for this field?
This makes me feel more intelligent because it convinced me that if I only put a little more effort into it I would be able to understand it all. Obviously I’m not going to put that theory to the test
Wait, what? How does that work, exactly? 🤔 Shouldn’t it make you feel LESS intelligent, rather than more? 😱 Otherwise, why would you need to put in that little bit more effort to understand something? 😳 Or am I missing something here?
@@aaronperelmuter8433Feelin like you’re on the verge of knowing the fundamentals of the universe makes him feel smart, and I feel the same way.. I never fully understand it, but for every video I have a new sentence or two of information that I am able to retain and that adds up
@@andrewpaulhartI LOVE that magical feeling of incipient understanding; but believing you finally understand something when you don't is not necessarily delusional; you might just be incorrect. True delusion requires believing you are correct even after Sabrina has proven you wrong. When watching Sabrina's videos, I quite often experience what I call Sabrina's-magical-5-minute-illusion. Her delivery is so logical and her explanations are so elegant that at the end of her video I truly do believe I understand something... for about five minutes.
@@2ndfloorsongs I stand corrected. … therefore better informed, which I’m convinced will contribute to making me more intelligent. It all works out in the end.
19:45 Thank you Sabine! You mentioned the statement "What you measure depends on how you measure it" in a previous video several times, but I've never understood what exactly this is supposed to mean. This time it's clear. Thanks!
Great video Sabine. I subscribe to the concept that all of the universe is fundamentally made of pure energy. What we refer to as “particles “ are nothing more than discrete packets of energy and the interactions forming larger complex particles are the result of interactions which form positive feedback loops leading to stability. Obviously this is already the basis of solving the equations which lead to the standard model. However once we threw the statisticians into the mix everything became overly complicated. The statistical studies really apply to the properties of the particles and not so much the fundamental existence of the particle. Here we are talking about information. It is observation that is probabilistic, not the particles themselves nor their actual properties. It is the forcing of our perception into the equations which has lead to the proliferation of statistical analysis and information theory. I hold that reality is all deterministic and based solely on perturbations in energy fields which can collapse into stable particles when they are in the state of positive feedback. Interactions of particles are again the process of recombining into a new positive feedback state. All this other gobbledygook is fundamentally about our ability to observe this simple phenomenon and not the particles themselves.
@@wiesawnykiel1348 I think so, just as they were in Dr Sabine's envelopes. The point of having hidden variables, that are real but about which we are ignorant, is that particles don't have to affect each other instantaneously.
Listening to Sabine I wish I could forget all the incorrect information I have listened to in my 70 years. Conditioning is a real problem as your brain keeps going back to the old patterns. Thanks for the videos. I am slowly getting a better picture…. from a person with an Arts degree. Love the dry humour as well🇨🇦
Don't let @schmetterling4477 catch this comment or you will get roasted about how there has been no misinformation by physicists and all of them apparently explain spooky action at a distance just like she does. Physicists don't explain it as two entangled particles actually being able to affect each other from mass distances instantaneously according to him. Apparently they've all been saying what Sabine said in this video the whole time and we have just somehow mistakenly perceived them as saying something else. Again this is according to @schmetterling4477, not me.
Thank You Sabine , … You CONSTANTLY EXPLAIN HOW ALL QUANTUM PERCEPTION IS THE INTER-EXISTENCE OF QUARKS WE ARE ALL COMPOSED OF … PARTING MUON PHOTONS OF LIGHT WITH ALL THE OTHER QUARKS YHWH CAUSED TO EXIST IN THE ENTANGLED BEGINNING OF TIME … more than 20 billion years ago . SO COMPRESSED IS THAT LATTICE , THAT THE MERE PERTURBATION BY ANY THOUGHT EVOKES THAT INSTANTANEOUS ENTANGLEMENT THE GREATEST MINDS CALLED “ SPOOKY “. Bell , pondered it , … Einstein , resisted it , and You , Sabine , ARE IN LOVE WITH THIS MYSTERY . This is Delightful to Watch ! You are GOING TO LOVE THE PERMANENCE THE LORD Creator Elohim , is going to WRAP YOU CONSERVATIVELY IN …WHEN YOU PERCEIVE YOUR UNLOSEABLE FOREVER , PERMANENT ENTANGLEMENT IN HIM . Ecclesiastes 3:14-15 “ For I know that whatsoever God doeth , it shall be forever ; nothing can be put to it , nor anything taken from it , and God doeth it that all men should fear before Him . For that which is , is the same as that which was , and that which was is the same as that which shall be ; for God requireth that which is past.” Psalms 36 : 9 “ In Thee , O LORD , is the wellspring of Life , and in Thy Light we shall see Light “ . Danke Fraulein
The understanding that the invalidation of local hidden variable theories via Bell's Theorem hinges on the assumption of measurement independence is not a new discovery per se, but it's a nuance that's often overlooked or not stressed in many explanations of quantum mechanics. Emphasizing this point can be crucial for two reasons: 1. Clarity and precision in scientific communication, and 2. Expanding the scope of possible solutions. Thank you, Sabine!
I love that she delivers absolutely everything at the exact same tone and cadence so it always takes me just a moment to catch that she made a joke, which is so much funnier than somone like Matt O'Dowd (who I also love)
I like her dry Humor also. But I am dismayed that she is a Materialist-Determinist who is grasping at straws. 'Super-Determinism' and 'Unknown Variables' are the Physicist's version of 'God works in mysterious ways'. Like all Materialist-Determinists she cannot admit that she is wrong and so she wants everyone to ignore the centurys worth of experiments in Quantum Mechanics and accept that we just don't understand 'God'.
Precisely when you said "wow, you are still with me, so glad you haven't left," I was thinking that this video should win sort of educational award. It's shockingly informative.
i was literally thinking to myself "this is the point where I'm starting to not understand, so I need to leave" and then she says that immediately as I thought that.
I was recently attending a course where the professor stressed that if you let go of the assumption of measurement independence, all problems go away (and you are a super determinist). So there's at least some physicists acknowledging this to their students.
Quantum measurements are anti information, in the sense that they partially destroy the quantity being measured. The implication being, no measurement can physically be made without producing uncertainty. One framing of the problem is to drop the assumption of measurement independence, another way to frame it is to add the assumption of fundamental non determinism. Non determinism must be in the observation, because the observer produced it! Measurement independence is a demonstration of why perfect information in the universe is a paradoxical concept. It's not just scientists that fail the measurement independence test, fundamental particles do the same. Consequently, variations of determinism that posit perfect information in the universe should be abandoned. They're potentially descriptive, but not predictive. All our predictions now take the form of probabilities that account for uncertainty. As it should be. As a non determinist that thinks the universe emerges from noise, it seems to me that the strength of quantum mechanics is that it embraces and describes non deterministic physical processes, in a way that even determinists must accept.
@jamesnicholl4730 - But even though the collapse is fundamentally random, it is still heavily weighted to certain outcomes. I like to think if it as determinism by large numbers, if you get what I mean. Over time, you will get the most likely outcome repeated over and over, so it still looks deterministic because of the statistical probabilities
@ElectronFieldPulse Couldn't have said it better. Just wanted to point out the fundamental non-determinism, it is the only way we know of to create truly random numbers.
As a 4th year physics major who just finished my last (*undergrad* upper division) quantum mechanics class, this is such a great comprehensive video! Wish it had been out while I took my class in the spring 😂 would’ve helped in the discussion of non locality
think of as AM FM radio. If you set the antenna to a particular voltage transmission, you can compose a message by modulating the repetition frequency of this particular voltage on and off, which is how Amplitude-Modulation radio works, tuning, listening to the repetition differences of a particular voltage. If you set the antenna to vibrate with a particular repetition frequency, you can compose a message by modulating the intensity of the voltage higher or lower, which is how Frequency-Modulation radio works, tuning, listening to the voltage differences of a particular frequency repetition. This means, beyond any mechanical physical properties interactions, the Universe fundamentally have two formal ways to act non-locally, either by tuning to a voltage (charge) intensity amplitude, listening to a bandwidth range of frequencies, or by tuning on a vibration (pulse) repetition frequency, listening to a sequence of different intensity amplitudes. Which makes of, understanding all of these, to really question the very basic needs of quantum wave, and particles interpretations. Good night. Have fun, Anna. Let's not break the collapsing function. (note: Yes, you cannot do anything at speeds faster than light, but yes, you can do anything in space at light-speed. You will figure this out.)
@@WackyJackyTracky At a certain degree beyond applied sciences, tenured researchers and professors are just twirling their thumbs and fingers... until they feet their stomachs growling and then they go eat. In other words, it's mostly "clever" linguistic BS. Oh, they know "real math" and such. But sound math, sound astronomy, sound physics, etc. aren't really involved in these nonsense (eg., "string theory" and how it's gonna usher in the next phase of science, "what's going on inside a black hole," what IMAGINARY things, particles, energy like "dark matter," "dark energy," etc are or are made of...) Us, little, uneducated people questioning these "string theory experts" and such is like farmers of Classical Greece questioning Greeks' "most learned scholars," asking them to explain what they meant when they said "the world is made of FIRE, EARTH, WATER, AND AIR. The answer, then, would have been: Oh, you poor souls... you have neither education or natural intellect to understand deep things like these. You should just put your head down and farm and leave the deep thinking and real science to the really learned ones... Today, you ask what "Dark Matter" or "Dark Energy" is... ZERO of these guys who have graduated at the top of their classes from Caltech, MIT, Princeton, Cambridge, Oxford, etc. in the last 50 years.... know ANY CONCRETE idea or detail of what they are talking about. But they swear up and down their "Ivy Tower" corridors they've found the deepest BS. Remember, in the early 1900s (when crazy Fritz Zwicky first came up with this "dark matter" BS, when Hubble was still trying to see of Andromeda was another galaxy or just a smutch of the Milky Way)... the "best and brightest" people like Sir Arthur Eddington had declared he and a few other deep intellectuals HAD already discovered all there's to know about the Universe... only post docs were needed to work out the tiny, less important details. Remember, that kind of BS, again, has been going on since BEFORE the Rise of Athens. And, again, early 1900s, the Milky Way was the only known galaxy in the Cosmos... and these crazies had already declared they knew everything on earth and in the Universe! By the late 1990s, too, remember.... 100% of the "best and brightest" in SCIENCE (astronomers, mathematicians, cosmologists, etc) were 100% sure the Universe was SLOWING DOWN... and poorly paid post docs, again, simply needed to work out the exact rate of deceleration... And this was NOT a very complex issue, compared to some others... as it was a binary situation: yes-no, true-not-true, accelerating-decelerating, etc. And virtually 100% of them got it wrong, when the average, random person on the street had a 50-50% probability of getting it right... ALL THIS is to say: Take most of these "deep stuff" with a very healthy amount of potassium salt: ----- "Planet Vulcan".... "ether".... "universe is not as you think it is".... "dark matter" .... "dark energy" .... "string theory" .... "quantum loop theory".... "inflation" .... "super-inflation".... Jesus/Dad & Uncle Allah vs. their former Archangels now known as Satan, Lucifer, the Devil.... "time ticked SLOWER at the beginning of birth of space-time/the Cosmos".... "the Cosmos has no center, because everywhere exactly the same... everywhere started at the same time and while the Cosmos is EXPANDING, it is expanding by CREATING space that was not there seconds before... but we are NOT expanding into nothingness out there," etc. I giggle silly, when well educated people use THE EARTH as an analogy to explain why or how there's no "center" to it (nor to the Cosmos): yes, there is! The Earth has a CORE and that's its center! It doesn't matter that you "can't find" a certain to earth while floating on a raft in the Pacific Ocean.. but earth DOES have a center to it.... because it is a SPHERICAL object... And if the Cosmos has a radius, or a diameter (doesn't matter which), of "93B light years" ---- so that, even within the 13.8B of our small patch of it, it is the same in every direction you look --- THEN it has a center to it (even if you have no idea where it is, from your tiny patch of space-time... like someone on a raft drifting in the ocean, in the Bronze Age, wouldn't know whether Earth had a center or not... because, you never know, it could have a point at some edge, where you "fall off" the face of the earth, as some legends had it...) It doesn't matter whether space-time is "flat," or it had a "negative" or a "positive" curve to it.... whether it is "spherical" or rectangular or any other shape or structure..... if the Cosmos is SAID to have a 13.8B or a 50B or a 93B or a 500B light year radius/diameter to it... then it has a CENTER to it, even if we will never be able to find it...
@@WackyJackyTracky @WackyJackyTracky first understand they are measuring particle spin, which is actually a charge intensity magnetic momentum angle on a pulsed repetition frequency. Now, after watching @Mavrik9000 answer on this video segment, then, one can infer as a) the energy pulse repetition on the first filter split into two different frequencies with charge of two different magnetic angle, b) after the energy radiation bounce off the two mirrors and pass thru the last filter, it recombines back into its original energy frequency repetition, forcing the magnetic momentum of the carried charge to align back to its original magnetic angle. There one still ask, what happen on the detector A? On the last filter, the radiation energy as it pass thru at different frequency repetition, and charged at distinct magnetic angle but same intensity value (or amplitude), these frequencies interfere on each other creating a bandwidth range of frequencies with magnetic mix angles but a uniform charge. Not the result expected to see in the detector A. Therefore, in principle, the experiment is not a failure, it is actually the concept, the interpretation of "waves" of "particles" for actually energy "pulses" repetition of "charges" intensity.
If I had seen this video in 1981, I'd have an MS in physics today. A beautiful, clear explanation. The papers with +1and -1 are Feynman-esque. Just brilliant.
+1 and -1 = 0 this is zero-sum-math, but our reality is a non-zero-sum-game in energy, biology, industry and security. I bought "The Feynman Lectures" in 1969 and in 2011 the NEW MILLENNIUM Edition. I don't know if i should realy read them or just buy brilliant/Sabine?
The "collapse" of a wave function is simply the terminology used to describe that the equation describing the probabilities of the wave function has been updated to reflect out observations. That explanation was very helpful.
Describing it with more words does not make it valid. e.g. if the wave function describes a tree of alternative outcomes, and you "update" it, then you're just pruning the tree, making a shape it would never naturally grow into.
@@DavidByrden1 Sabine is a super-determinist, so there isn't a wavefunction-collapse problem for her. But she fails to deal with the implications of super-determinism. All roads lead to insanity.
The collapse of the wave function was a rather ad-hoc invention in the early days of Quantum Mechanics to have a rule at hand for computing measurement outcomes. It doesn't make the general QM descriptions invalid at that particular incident of time. For instance, in decoherence theory, it is possible to follow and describe this kind of "collapse", and in quantum optics and QED, that's possible too. If I'm not mistaken, there are even remarks on that topic in John von Neumanns old book about quantum mechanics, in the chapters where he describes the interaction of test species system and environment - but I'd have to check that again.
❤❤❤ This video is EXACTLY the right length! OMG I think I finally understand! Holy cow! Yes the statement that "John Bell ...forgot" is blowing my mind, but not because of science. I thank you for the comments you make right after that, because it helped me to be sure that I wasn't nuts and that you didn't misread your script. I will say this: the word "entangle" seems to be intentionally misleading, no matter which suffixes they use with it. Therefore, whoever first wrote that a particle was "entangled" was lying. YOU are magnificent! And yes I needed help understanding the 2022 Nobel, too. If it were up to me, no physicist would be allowed (by their peers!) to use the mystical-sounding word "entangled."
As a quantum physicist, I agree with everything she said. BUT - What she failed to emphasize here (although she did in her other video about free will) is that measurement independence is something any sane (typical) person would say must be true if the two measurement locations are separated by thousands of miles (or metres). So, when the three No-Bellists did their experiments with far-separated detectors, it does seem very strange that they see the results they do if one 'believes' in measurement independence at a distance. The more you think about this, the stranger it seems. That is, it is impossible to 'understand' how the world can be the way it is. I don't call that thought 'woo,' it is physics and points to a still unclear aspect of the theory called the quantum measurement problem. Google that if you like.
Its still quantum woo. Her envelope analogy is incorrect. A proper analogy would be to put +1 and -1 in one envelope, and the same in the other envelope. Remember, they are in both states at the same time. When Alice opens her envelope, its -1, and John’s is +1. That’s very weird.
@@astrumimitari7467 Is her analogy truly incorrect? Wouldn't placing both a +1 and a -1 in each envelope equate to placing two particles in each envelope? This is simply the left-or-right shoe analogy other physicists use to describe entanglement, albeit with different names for the parts. Or is that frequently-used analogy also incorrect?
@@fantalimon1454 No, not two particles in each envelope necessarily. I mean yes, but each particle is in two states. The +1 and -1 are not particles, they are states of the particle. Since each particle, before measurement, is in two states at the same time, then those two states need to go in each envelope. Two unmeasured particles have 4 states.
@@scene2much There's no shame in rewinding some part several times to gain a sufficient understanding. Had to do it plenty of times. Knowledge is often a challenge against the self.
It's likely fake or something, politically speaking science has become somewhat suspect. The degree=validity system of social interaction only came into existence when the federal government banned employers from ability testing their own prospective employees to help realize the civil rights mandate, companies then used college degrees as the next best costly signal indicating qualities they could no longer test for. Physics ran out of things to do after the Standard Model proved entirely correct and now needs to protect it's considerable financial endowments, it's in a similar situation to Southern Poverty Law Center who have long since defeated the KKK but need to find reasons they're still taking people's money. Meanwhile I feel for quantum computers what most probably do: There's no one deserving of this power, no good will come from anyone having it. Physics is proving to be more trouble than it's worth, it's theories are either performative falsehoods or a symphony of doom heralding some new way for science to humiliate mankind and endanger continued life on earth. Physics is perhaps best not studied, that will be the majority opinion among even atheists before this woman is even dead probably. The fact the first quantum computers will be used for the surveillance of dissidents is exactly why the human scientific story needs to come to a plateau beyond just mere fearful Luddism.
Except that it’s not correct. Sabine is wrong. QM is a locally causal theory. It’s hidden variable models that must either be non-local or violate measurement independence.
@ToddDesiato If you understood what SH said, maybe you could explain to me how it works in the Mach-Zehnder interferometer (from about 16:40). If a photon hits beam splitter 1, does that mean it only has one of two "hidden variables"? Either "hidden variable 1" (then it "reflects") or "hidden variable 3" (then it "transmits")?
@@ToddDesiato What if, after leaving beam splitter 1 (the photon had "hidden variable 1" and was reflected from BS1), we insert mirrors and direct the photon at beam splitter 2, which means that interference must occur?
Indeed this video is a gem! I still have to chew on some steps, but gives new (to most of us) perspective on an extremely controversial topic, with the only things sure about it that it has been misinterpreted in the vast majority of cases.
nonlocality is real because we can remote viewand have precognition and clairsentience. those things i do all the time and it is more convincing to me than any theory..
Actually mind transcends matter .. i can appear to people remotely . what i dont know is whether i could move objects at a distance. i can appear to move objects and i know if objects are moved at a distance.. i just dont know if i can actually move an object at a distance. i did experience a friend moving an object in my house from a distance. its far more interesting experimenting with reality than theorising.
I've already watched about 20 videos on Bell's theorem and your stealth explanation was glorious. Your disambiguation of entanglement and Bell's theorem was eye opening since I among many others, as you mentioned, thought they were concerning the same thing. I 'think' I finally kinda get it without all the 'quantum' hand-waving and also clarifies why Entanglement doesn't seem to be the way for FTL communication. Thank you so much, nothing better than that feeling when you start to 'get' complex topics. Still makes my head spin but in the best possible way.
Now I finally know why "spooky actions on a distance" as It has been described never made any sense to me. Ever since I was a child I thought it was something I didn't understand, but now it's all clear (or at least a bit clearer). Thanks.
I agree 100% Sabine did an outstanding job explaining this segment. I have heard about entanglement so many times before but it never really clicked until now. Thank you!
12:22 Well, it does, in the sense that (you don't mention this but this is very important) the spin measurement is _direction-dependent._ THIS is what makes it so unlike the pair-of-envelopes situation. This again pops up at 15:21, the +1 or -1 spin measurement involves a _choice of direction of this measurement,_ and particle A "knows" the _choice of measurement direction of the spin_ that B had made. But this choice of direction is simply the experimenter B's _choice_ (not an experimental result but an act of B's free will, if you like the word). So _this_ is the big mystery. And Bell's inequality is precisely about quantifying certain probabilities pertaining to those choices of directions of spin measurements. 17:43 I don't think it's as easy as this. AFAICT John Bell's setup is needed to exclude local hidden variables. The Mach-Zehnder setup OTOH involves two measurements (the two half-silvered mirrors) and who is to say the first did not change the hidden variables to make the second mirror always direct the photon to B? Again, I think that this video decided to oversimplify the problem by ignoring the spin-measurement direction dependence which is absolutely _crucial_ to this mystery. (Mathematically, Bell's inequalities are about certain very clever but simple relationships between trig functions of angles between those spin measurement directions.) There is more to say about all this but I need to run some errands now, so maybe later...
Absolutely! The direction of measurement, or some kind of mode of measurement is ESSENTIAL for Bell's inequality. It means nothing without it, and would say nothing otherwise; abosolute zilch. I watched all this...waiting for mentioning why this is NOT a pair of envelopes. Unless is (uh...excuse an analogy) a pair of envelopes if alice open one 90 degrees to bob's and finds its 50/50 chance of being the opposite of bob's but opening it the same way up, would be 100% chance of opposition. HMM, well envelopes don't tend to work like that... So Bell's inequality is about whether this direction mode is determined first or at measurement, not the specific -1 or +1 spin at all! In an experiment we can assess the total probabilities can't we, not generally the specific -1/+1 spins and it would be not possible to pick out the difference at 0 degrees or 90 degrees, giving the same total probabilities of -1 or +1 for either theory. If we measure inbetween, however we get very different probabilities. is the number >2 is the question. At 45 degrees we get an answer of more than we expect than with a hidden variable theory*. Its more correlated to the CHOSEN direction at the time of measurement always, so we know along the CHOSEN direction it must satisfy +1 and -1 for each particle....not the potential for any random possibility of +1, or -1 each 50-50 (because in the case of the hidden variable, our measurement doesn't affect outcome, so the direction picked could be the wrong one, the right one, or any angle inbetween because it would have had to be determined first. this simply isn't the case.). *of course there are OTHER hidden variable theories that fix loopholes...well, wormholes in fact such as ER=EPR?
@@jorgepeterbartonI REALLY don't s e how that analogy proves anything. Imagine the information written on that type of polarized image cards, in which there are two images depending on the angle. Great, so one direction of measurement tells you nothing, because you don't actually know the spin yet, do you?; the other gives you precise information on the spin of one, so you can logically deduce the other's.
@@TheDude-w5lthats not the point to “deduce” the other information. If was this point, so is very obviously and no mistery. The point is. The particule DOESNT have the information until you measure it, they have both. You can see the bells theorem probabilitys and see that the wich info that the particule already has the opposite information of the other after the measurement doesnt applies to lab. Please see this experiment in videos. For some way, seems that measuring the entaglement particule affects the other particule, this is CLEAR in studies. Its not like, all right, this particule has +1 so of course, the other has -1. Its NOT this point!!
Using your example, you can study more in the way that: If the particule has both infos, when you measure it it has info A. How the other particule, that has BOTH infos until you measure it, instantaneosly show the info opposit? No matter how long in distances they are, the entaglemnt particule are affected by the messure of the other! Again, affected by measure of the other….
You would be advised to look up Professor Jean Bricmont's numerous youtube talks on Bell's Inequality. Here is his response to Sabine: Jean Bricmont Ok here is my response (you may post it): I am not sure that SH really understands what statistical independence means (although other people have already tried to explain it to her). To quote S. Goldstein, T. Norsen, D.V. Tausk and N. Zangh\`{\i}: Bell's theorem, {\it Scholarpedia} 6(10): 8378 (2011) (which is quoted in my book Making sense of QM): ``if you are performing a drug versus placebo clinical trial, then you have to select some group of patients to get the drug and some group of patients to get the placebo." But for that to work, you have to assume ``that the method of selection is independent of whatever characteristics those patients might have that might influence how they react to the drug". If, by accident, the people to whom the placebo is given were exactly those that are cured spontaneously, while those to whom the drug is given are so sick that the drug has little effect on them, then of course the study would be biased. And no matter how ``random" the chosen sample is, this will always remain a logical possibility. This is an example of what is called statistical independence. But the same sort of assumptions is used throughout science. Turning to the EPR-Bell experiment, statistical independence means that the properties of the incoming particles (electrons or photons) are independent of the direction in which their spin or polarization will be « measured »; but since the latter can be chosen in an arbitrary way (by random number generators, by the digits of pi, by the letters in the Bible or the analects or by the evenness of the number of stars in a portion of the sky) even when the particles are in flight, denying , statistical independence means that one assumes incredible correlations between the properties of the incoming particles and not only the method used to choose the direction in which the spin or polarization will be « measured », but also with the properties of the random number generators, of the digits of pi, of the letters in the Bible or the analects, of the evenness of the number of stars in a portion of the sky or of any other system used to make that choice. This is the same problem as the one with the placebo mentioned above, only much much bigger. Some people think that what SH assumes is just universal determinism, à la Laplace. But no! She is assuming very subtle correlations whose existence does not follow from mere determinism. For example, one can say that there is no correlation between the amount of rice produced in China and the number of car accidents in France, in a given time period, even though both are determined (in a deterministic universe) by the initial conditions of the universe and one can multiply such examples ad infinitum. In fact, if one accepts the correlations that SH assumes, one can « save » any superstition one wants. Take astrology: most of its predictions are never checked, but when they are (taken at random) they usually fail. But one might argue, à la SH, that there is a subtle correlation between the fact of checking an astrological prediction and its veracity, so that all astrological predictions are true except the ones one checks. In the end, SH assumption is no different from the Duhem-Quine thesis in philosophy of science: any theory can be held true if one is willing to make sufficiently ad hoc assumptions in one’s system. So there is nothing new here and Bell’s inequality and its verification do prove the existence of actions at a distance, at least according to normal scientific reasoning. Best, Jean
I don't know this guy you are talking about, but violating statistical independence, doesn't mean there is a magical process that correlates the settings of the measuring devices with the results. In the example you gave, the settings of the random number generator function *literally* are "incredibly" correlated with the results of where the placebo is distributed. The settings literally decide where the placebo is distributed, deterministically. There is no reason why this couldn't also happen in a quantum experiment, between the settings of the measuring device and the collapsing.
@@giorgosg4032 Quantum Physics Professor Jean Bricmont (expert on Bell's Inequality): "The mere assumption that there are pre-existing values leads to a contradiction when one takes into account the statistics of the results when the directions are different....But nevertheless, some action at a distance does take place" History of Quantum Mechanics or the Comedy of Errors (Published by International Journal of Quantum Foundations on March 28, 2017, Volume 3, Issue 2, pages 31-64) by Quantum physics Professor Jean BRICMONT: "The goal of this paper is to explain how the views of Albert Einstein, John Bell and others, about nonlocality and the conceptual issues raised by quantum mechanics, have been rather systematically misunderstood by the majority of physicists...In any case, refusing to face a problem is not the same thing as solving it. One thing is certain: nobody has yet proposed a local explanation for those perfect correlations, and indeed nobody could do so, since Bell has shown that it is impossible. quoting from S. Goldstein, T. Norsen, D.V. Tausk and N. Zangh`ı: Bell’s theorem, Scholarpedia 6(10): 8378 (2011) note 14: J. S. Bell, Bertlmann's socks and the nature of reality, 1980, available online, reprinted in J. S. Bell, Speakable and unspeakable in quantum mechanics, Cambridge, 2004, p. 149-150 (p. 10 in the online version), emphasis in the original. John Bell quote (also quoted by Bricmont): "Let us summarize once again the logic that leads to the impasse. The EPRB correlations are such that the result of the experiment on one side immediately foretells that on the other, whenever the analyzers happen to be parallel. If we do not accept the intervention on one side as a causal influence on the other, we seem obliged to admit that the results on both sides are determined in advance anyway, independently of the intervention on the other side, by signals from the source and by the local magnet setting. But this has implications for non-parallel settings which conflict with those of quantum mechanics. So we cannot dismiss intervention on one side as a causal influence on the other." Back to quantum physics Professor Jean Bricmont: "Finally, one should emphasize that Einstein’s speculations, which looked purely philosophical or even “metaphysical” to many, have led to what is probably “the most profound discovery of science”, to use Henri Stapp’s apt phrase [62, p. 271], namely the existence of nonlocal effects in the world. And the EPR and Bell papers laid the foundation for the quantum information revolution. This should be a lesson for “pragmatists”. Professor Jean Bricmont - Bell and nonlocality lecture posted on youtube channel (see below) "each side sees a perfectly random sequence...whatever the measurements are, that's true...But, if each person tells the other what measurement they've made WITHOUT telling the result... Then they both know which result has been made on the other side...which is some form of information, of joint information....some sort of nonlocal transmission of information has taken place." 2.2K views 10 years ago Quantum Theory without Observers III - Talks This is a talk held at the conference "Quantum Theory without Observers III" (ZiF, Bielefeld, 22.04.-26.04.2013). see also on youtube: Jean Bricmont, Université Catholique de Louvain talk What Did Bell Really Say? 2014 Metaphysics Within and Without Physics Conference June 7-8, 2014, Western University, posted on Rotman Institute of Philosophy youtube channel and Jean Bricmont: Einstein, Rosen, Podolsky (EPR), Bell and Nonlocality 3 years ago Summer School on Paradoxes in Quantum Physics Summer School on Paradoxes in Quantum Physics September 1-6, 2019 posted on John Bell Institute youtube channel So Bricmont explains the de Broglie-Bohm Theory gives the rational complemention of Bell's Inequality nonlocality since it "represents the positions of the particles that exist, independently of whether one “looks” at them or one “measures” them. ...the result of any quantum measurement will be determined beforehand by the quantum state and the configuration of the “mea- suring device”. ...This is related to (and explains) the nonlocal character of the de Broglie-Bohm theory....This is one of the ways that the action at a distance manifests itself in the de Broglie-Bohm theory....The fact that the de Broglie-Bohm theory is nonlocal is a quality rather than a defect, since we just showed that any theory accounting for the quantum phenomena must be nonlocal."
Thank you, Sabine! You've done an excellent job of explaining locality and entanglement. I was a bit shaky on this area of my casual interest and self-delusion of understanding the basics of quantum mechanics and you helped me tighten it up a bit more.
0:00: 🌍 The video discusses the concept of locality and its connection to quantum mechanics. 3:32: ! The example of the two envelopes with correlated numbers demonstrates non-local descriptions of reality. 7:18: 🔬 Quantum mechanics is non-local in nature and the wave function may describe knowledge rather than reality. 18:53: ✅ In quantum mechanics, a photon can take two paths and interfere with itself, but measuring the path requires non-local collapse. 11:25: 🔬 Quantum entanglement does not allow for faster-than-light communication. 15:04: 🔍 The video discusses the non-local causality in quantum mechanics. 22:19: 🔬 The video discusses the non-locality of quantum mechanics and the concept of superdeterminism. Recap by Tammy AI
Wow! Sabina does it again. The reliance on violation of Bells inequalities always made reality seem more mysterious, unjustifiably so. Eye opening info.
I know Sabine is big on superdeterminism, but I think she underestimates how philosophically repugnant it is to most physicists. That's the real reason most don't take it seriously.
@@jameshart2622 I'm fine with measurements affecting results in some way.. But I'm not fine with that measurement affecting the result of an entangled particle light years away. If I understand it correctly, superdeterminism would imply that the particles somehow knew which measurement was to be made at the time of entanglement.. Thats much harder to bite then non-locality or non-realism.
@@jameshart2622 That's an interesting statement since during the early development of quantum mechanics, one of the things that classical physicists found repugnant about quantum mechanics was that quantum mechanics (in the Copenhagen interpretation) is non-deterministic unlike classical Newtonian mechanics. In the early years of Newtonian mechanics, many philosophers and scientists found the determinism of Newtonian mechanics to be repugnant since it precluded free will, which is what many philosophers and scientists nowadays find repugnant about superdeterminism. In the 18th and 19th centuries, with the development of thermodynamics and classical statistical mechanics, philosophers and scientists consoled themselves with the fact that since predicting the states of all of the matter, energy, and forces in any given closed system at some time in the future required exact knowledge of the states of all of the matter, energy and forces in that closed system at some time in the past or present, which could not be known exactly by anyone operationally due to practical measurement errors, then the future was operationally not predictable exactly, but through statistical mechanics, it could be predicted statistically. Those in the free will camp accepted this compromise because it meant that since no individual could predict the past influences on nor the future outcomes of their or others actions exactly, individuals were operationally free to choose their actions even though the actions and outcomes for a collection of individuals could be predicted statistically. Those in the determinism camp accepted this compromise, since mechanics was still fundamentally deterministic if one had all of the necessary exact information. Development of chaos theory for classical mechanics in the 20th century just reinforced how the measurements of the initial states had to have exactly zero errors in order for the states of many bodied systems to be predictable beyond a certain time in the future without large errors since small errors would grow exponentially with time. Chaos theory was summarized by Edward Lorenz who stated, "Chaos: When the present determines the future, but the approximate present does not approximately determine the future." I think that the philosophical repugnance of superdeterminism is widespread only among the previous generations of physicists still living because they were indoctrinated with the Copenhagen interpretation of quantum mechanics and the promise of free will through indeterminism in that interpretation of quantum mechanics. The fact that Bell and others at the time did not even realize that measurement independence was an assumption underlying Bell's interpretation of the meaning of his inequalities is evidence of how indoctrinated they were. Even after this tacit assumption was pointed out by Shimony, Horne, and Clauser (1976) about a decade after Bell's proof of his theorem was published in 1966, rather than questioning this assumption, it was elevated to the status of an axiom. It should be noted, that there are essentially two ways to reject the measurement independence assumption. One is to suppose a common cause in the past that determines both experimental settings and experimental outcomes, as in the work of Shimony, Horne, and Clauser (1976). This sort of account has been called superdeterminism. Another avenue was suggested by Costa de Beauregard (1977), in a comment on the interchange between Bell and Shimony, Horne, and Clauser. Costa de Beauregard objected that the discussants were disregarding the possibility of retrocausality, a possibility that he had advanced earlier (1976). If causal influence from future to past is admitted, then, even if the settings are regarded as free variables, they could influence the state of the system at the moment of preparation, contravening the assumption that the preparation probability distribution be independent of experimental settings. In the interchange between Bell and Shimony, Horne, and Clauser mentioned above, Bell makes it clear that no metaphysical hypothesis of experimenters exempt from the laws of physics need be invoked. What is needed is something considerably weaker than the condition that the variables not be determined in the overlap of the backward light cones of the experiments. What is needed is that they be “at least effectively free for the purpose at hand.” Bell argues that a deterministic randomizer that is extraordinarily sensitive to initial conditions would suffice to provide the requisite independence, and that variables of this type may be treated as if they have implications only for events in their future light cones. The upshot of the interchange was substantial agreement between Bell and Shimony, Horne, and Clauser. Shimony, Horne, and Clauser consider the assumption of independence of settings and the state of the particle pairs to be justified, even though relativistic causality does not mandate this independence. Thus, although Shimony, Horne, and Clauser initially questioned the measurement independence assumption, they ended up accepting the assumption as being justified, but not mandated. As an interesting and somewhat related aside, the many-worlds interpretation of quantum mechanics challenges an assumption of Bell's analysis that is different from the measurement independence assumption. Though it might seem that this goes without saying, Bell's entire analysis is predicated on the assumption that, of the potential outcomes of a given experiment, one and only one occurs, and hence that it makes sense to speak of the outcome of an experiment. The reason that this assumption is worth mentioning is that there is a family of approaches to the interpretation of quantum mechanics, namely, Everettian, or “many-worlds” approaches, and some variants of the relational approach, which hold that all outcomes occur in what are effectively distinct worlds. The many-worlds interpretation is local and deterministic since it consists of the unitary part of quantum mechanics without collapse of the wavefunction. It can generate correlations that violate a Bell inequality because it violates an implicit assumption by Bell that measurements have a single outcome. In fact, Bell's theorem can be proven in the many-worlds framework from the assumption that a measurement has a single outcome. Therefore a violation of a Bell inequality can be interpreted as a demonstration that measurements have multiple outcomes. (See Deutsch, David; Hayden, Patrick. "Information flow in entangled quantum systems". Proceedings of the Royal Society A. 456 (1999): 1759-1774. and Brown, Harvey R.; Timpson, Christopher G. "Bell on Bell's Theorem: The Changing Face of Nonlocality". In Bell, Mary; Gao, Shan (eds.). Quantum Nonlocality and Reality: 50 years of Bell's theorem. Cambridge University Press. (2016) pp. 91-123.) I think younger theoretical physicists are willing to at least acknowledge that measurement independence is an assumption that can be questioned rather than an axiom that must be accepted. Once this happens (and it does seem to be happening now), then the consequences of accepting or rejecting this assumption, and if rejecting this assumption, whether it should be rejected based on superdeterminism or retrocausality, will be worked out by theoretical physicists. Then theoretical and experimental physicists will collaborate on ways to experimentally test this assumption. If acceptance or rejection of this assumption does not lead to testable predictions, then it is not a legitimate constituent of scientific theory, but it is, instead, philosophy and specifically, metaphysics. As such, one may accept or reject a metaphysical belief based on the subjective feelings that it engenders like repugnance or delight, which should be irrelevant in deciding to accept or reject a scientific theory. In any event, from a historical viewpoint, this is just another chapter in the age old debate between free will and determinism (with the possibly new wrinkle of adding the third choice of retrocausality to the debate). Interestingly, Bell's argument that "a deterministic randomizer that is extraordinarily sensitive to initial conditions would suffice to provide the requisite independence" sounds eerily similar to the compromise between free will and classical determinism engendered by the development of statistical mechanics and reinforced by the development of chaos theory, to which I alluded earlier.
@@jameshart2622 I could be wrong, but in my humble opinion,ones preferred philosophical stance should have no bearing on what direction physics takes. Whether one finds the theories philosophically palatable or not, should have no bearing on physics. Physics is not philosophy.
Wow this was really helpful, thanks for explaining this so clearly. I was curious and was worried that this would be over my head. You presented the info in an interesting way and in an accessible way.
John Bell himself acknowledged the logical possibility of no measurement independance in his 1980 paper "Bertlmann's socks and the nature of reality". His view was that :" this way of arranging quantum mechanical correlations would be even more mind-boggling than one in which causal chains go faster than light."
So I see it as well, Sabine multiple times says.. yeah non-independence is a thing, but does not explain what it means if you got that route.. (say you do the experiment with different angles to measure spin, what does it mean, its all predetermined and thus independent, what angles you measure, especially if you say use the CMB as source for your "random" decissions.. so its all connected? great way to "rescue" locality having it abolished completely by saying every part knows everyhting anyway)
@@mahasamatman12 Maybe asking for an interpretation what non-independence actually means, only gets a "shut up and calculate" answer again, okay.. but then nothing gained by this either.
@@BarriosGroupie Sure, but that is not the entanglement Bell is talking about in the above quote. He is talking about the type of mysterious conspiracy that would be needed for the measurement independence to be violated, i.e. for the 2 photons to "know" from the start what Alice and/or Bob will chose to measure.
There was always something about quantum entanglement that didn't sit right with me, but for all these years I couldn't put a finger on exactly what. You explained it in a way that I think I finally get it. Thanks!
if all of qp ever "sat right with you" you didnt understand it. At it's core qp is nonintuitive. Something that tells me this intuitive misunderstanding is common is the inate misunderstanding a lot of people have of wave function collapse. They believe the math has power..that wave colllapse is a "force" as it were. It isnt. The math doesnt determine when you know a particles state. It explains why you didnt have the data before that point. It is explanatory not predictive
@@charlesreid9337 I disagree that measurement and apparent "collapse" is part of quantum physics. Quantum physics is perfectly intuitive as long as you don't insist on wave function collapse.
@@psychohist it requires a lot of education before you realise the universe operates on statistics and it becomes intuitive though. At least for me. I agree about collapse humans gavee a bad tendency to think mathematics cobtrols or creates physics. It doesnt..it predicts it. It helped me a lot when a mathematician described it as an incredibly logical and predictive a language. in sumole algebra you can convert certain questions directly to algebra. In programming languages convert english to math and operations
Very nice video, even though I feel it goes over my head at some points. But trying to explain something complicated to us watchers is very much appreciated Sabine!
Thank you Sabine. I didn’t manage to follow the whole video, but your explanations of wave functions, collapse of wave functions, and entanglement were the most accessible that I have seen or read. They really improved my understanding. 🙏
i had to pause the video just to say how amazing the explanation is!!! i really thought (after watching other videos about entanglement/spooky action at a distance) that doing something to one (entangled) particle changes the other particle. as i am no physicist i thought i just wasn't able to grasp the concept. but it seems quite logical the way you, Sabine, explain it! thank you so, so much!!!
Thanks for the lesson, Sabine! 😊 And yes, I watched it all and understood it. What probably means I don't understand anything, but... Details. 😬 Stay safe there with your family! 🖖😊
This was really good - but also I am confused about one part. In the letter example, the real determination was made when the letters were sent (even if they were not observed until the letters were opened). My previous understanding (from the double slit experiment and the 3 polarized lens example) was that the actual determination happened latter - ie after the pairs were entangled. So... could you be more clear? Is the observation just uncovering the correlation that was already decided or did the "decision" happen only once the envelopes were opened. In that case, it would be like sending two blank pieces of paper - and once opened one read "+1" and the other read "-1".
I believe she is saying that physicists are debating that & she believes the correlation happens while the two parts were together. No spooky action at a distance; only hidden variables. The violation of measurement independence gives the impression of blank pages writing the numbers when the envelope was opened. If you want to know more about the violation of measurement independence she suggest you check out the literature on it. I also got a little lost on the multiple mirror part. I was trying to figure out why the half-reflecting mirrors ended up sending everything to one location. Apparently it had something to do with wavelengths causing the violation of measurement independence.
Thanks Sabine! I have heard a few physicists mention the measurement independence assumption but they point out experiments in which light from distant quasars is used for randomness and how unlikely it seems that could predetermine a measurement choice. How would you respond?
i want a shot at this question too sry, i believe that sabine thinks the choice was predetermined from the start of time- super determinism I personally believe the moon is not there unless you look at it.
The bottom line is that superdeterminism is a very contentious issue. Most physicists working in this area do not subscribe to this interpretation. I have some colleagues who are actively working in this area, and they certainly do not accept superdeterminism as a preferred explanation for the violations of Bell's inequality.
As a non-physicist, but simple mathematician, I always struggled with the implication behind Quantum Mechanics and always taken for granted the Hidden Variable theory was not possible, even though it always fascinated me as a concept. After looking a bit into it, it is for me now very obvious that "superdeterminism" is actually a much more interesting explanation for the quantum effects we see. Seems a bit arrogant to think that simply because we cannot know certain things, the world must be governed by randomness. Thank you for your videos, the provide at least some comfort.
Wait, it's arrogant to think that because we can't explain a phenomenon it has to be governed by another law that we might one day discover, but isn't it arrogant to think that we'll never be able to accurately measure the phenomena of the universe on an absolute level because there's randomness?
Exactly what I was just thinking to myself. Sabine finally convinced me that Superdeterminism probably describes reality in another recent video. It's something I'd struggled with for years and the single point that was making me resist the idea was the fact that it doesn't allow for free will. The reason I had difficulty letting go of the idea of free will is that I'd always believed that was the entire purpose of sentience/consciousness/awareness. So, that's the area I had to focus on and I eventually managed to come up with a reason for the existence of sentience that doesn't involve free will. I won't go into what my conclusions were here... it would take too long, but the point is, I succeeded (btw... the answer is not flattering). Watching this latest video has only reinforced the case for Superdeterminism in my mind. As difficult as this concept may have been to accept, the alternative is even more out there (spooky indeed!). I don't have any problem at all with the concept of hidden variables. All it means is that Quantum Mechanics is not a complete description of reality, just as General Relativity isn't a complete description of reality. General Relativity gives us equations that are very useful for describing the Universe at the scale that we can directly experience and observe (the macro). But what General Relativity describes very well emerges from another level, it does not describe that level at all so it tells us nothing useful about the internal properties of black holes, how the Universe came into being or the quantum world. This is where Quantum Mechanics comes in. QM gives us equations that are very useful for describing the reality that gives rise to the macro world that General Relativity describes but is not useful for describing the world at the macro scale. I have no difficulty in accepting that QM may be limited in the same way that General Relativity is limited, in that it doesn't describe what underlies the emergent properties of the quantum world (the hidden variables). I'm very much inclined to believe that, as Sabine suggests here, the wave function describes a feature of our knowledge, not objective reality. If I toss a coin and let it drop to the floor, what's the chance that it will land heads up? Most would say 50% (50/50) but this is not so. In reality the chance is either 100% or 0%. There is no in between, it's just that we don't know which value applies before we see the result. Not knowing an answer does not make that answer unknowable. That would be a rather arrogant conclusion, even for me! 😅
@@antonystringfellow5152 I think it is equally, indeed, several times more arrogant to assume that determinism (a theory created by the human mind) is true at some level that we cannot know or be sure of the existence (just assume) than to assume that the universe it has an uncertain nature that escapes our ability to know.
It feels wrong that stuff like the spin of an single particle will correlate with what I try to detect before I decided what to do. Even if everything is super-deterministic shouldn't that sort of thing be pseudo-random?
@@lubricustheslippery5028 Yes, exactly thats what I am saying to the other of Sabine's videos about superdeterminism. Even if we assume superdeterminism is true, this doesnt solve the problem. Still, on average, you should get random events and not those corelations. Since you are getting those corelations between what you choose to measure and what you end up measuring, then you still have to make some laws that explain those corellations. Otherwise you can disregard all laws, and say that everything derives from superdeterminism.
So given particle A and B are entangled and measuring a property of particle B can lead the collapse of particle A's wave function Let's say you produce a high number of pairs of such entangled particles, and on one end measure the property of all particles B and on the other direct all particles A through a double slit Now, will you observe an interference pattern? The collapse of the wave function suggests no. Does this mean you can tell whether the particles B are being observed? If you stop observing particles B, can you tell that this is the case because the wave function will be upheld and you'll get the interference pattern?
very good explanation, especially pointing out the "hidden" (forgotten, ignored) assumptions, in this case "measurement independence". The best part was your explanation, why it might be that physicists fail to mention a crucial (and not necessarily self-evident) assumption for the "proof" that "QM is non-local".
Good explanation and well presented. There is another alternative hypothesis that does not violate locality and still causes the "type 1 non-locality" (as you put it). However, I'm still writing out the maths for it because my calculations don't rely on probabilities and are repeatable and deterministic. So far everything is looking like my hypothesis may be correct. However, after the finalized calculations, I'll have to set up a lab experiment to ensure the idea is accurate. Needless to say, this is a long and expensive project.
I'm going to be honest, this sounds like a lot of the perpetual motion machine ideas. I'd love to be proven wrong, but I'm a bit skeptical when you give no information and what goal you have by writing this out.
@@reasonerenlightened2456 No. Sentience is irrelevant. Measuring sub atomic particles requires interacting with the system, such as putting energy into the system and seeing what changes, its not possible to observe quantum mechanic as an 'outside observer' and that is the problem. Basically, its not like watching an argument between two people through binoculars, its more like trying to stand in-between two people arguing, your presence will change the dynamic and likely the outcome. So the "act of measuring" will influence the outcome, because it injects new variables into, or changes existing variables in, the system.
Absolutely fantastic and undeniably forceful, your method of logical reasoning to describe logical reasons for needing to be able to actually make the science free of inherent inconsistencies it doesn't require to work. I am not able to even follow everything the first time so that I can then induce the process myself without tripping over my perception and I give this video especially nothing but praise. I hope I can manage to comprehend the lesson on quantum mechanics you put together on Brilliant, I had to stop 3/5 or so through it to regroup as I am recently trying to make up for 20 years of reading the ideas without learning the mathematical foundations underpinning them, and I hope you keep making challenging videos for me to wonder if it's not so, even so; respect.🙃
Thanks so much!! I've thought this while reading about non-locality, but was never really sure if I was correct. There's so much misleading information about this subject that it's truly a shame.
Thanks This video by far gave me the largest amount of understanding on my path to actually comprehend the problem and Bell's explanation of it. I still don't really feel like I'm there, but I've never felt more confident that it's possible.
I don’t think I’ve learned anything, but this was entertaining, weirdly enough. I hope people who are genuinely interested in this topic will find it even more insightful and entertaining than I did. Godspeed!
I would love to see a video about your "Supermeasured" paper, because the idea that e.g. a photon "knows" what measurement will take place (correlations between hidden variables and measurement settings) seems bizarre, but probabilities arising from the geometry of the statespace seems really intriguing!
That would be the superdeterminism she mentioned at the very end, and she has done at least one video about that before. Basically it amounts to the photon "knowing" what measurement will take place because the measurement was predestined at the moment of the big bang (obviously not actually that simple as that would also be the way classical determinism works and that's not what we need here. Should look up her other video for more info if you want, but that's the superlayman description).
@altrag It's deeply unsatisfying to me to accept the kind of "conspiracy" (scare quotes) needed so that measurements always come out just so, that the physical correlations present at the big bang would translate to correlations in a macroscopic phenomenon like labratory measurement. Even retro-causality seems more plausible! But the supermeasured paper seems to address this by pushing the correlations to the geometry of the state space (not in the distribution of hidden variables in physical systems), which I'd really like to know more about! But that doesn't seem to be what you're describing.
The supermeasured paper argues (iiuc) that Bell's statistical independence is a much stronger assumption that what it's often interpreted to mean, physical statiscal independence, and shows that the latter can can be satisfied while the former is violated.
Measuring an entangled particle doesn't change the information at another entangled particle, but it DOES collapse the wave function of the other entangled particle. And since particles with collapsed wave functions behave differently than particles with non-collapsed wave functions (as in the double slit experiment), FTL communication is possible. Right? By putting an emitter halfway between a double slit and a detector with the detector very slightly closer), the double slit will change from interference pattern to slit pattern almost instantly when the distant detector is turned on, regardless of the distance between them.
As painful as this entire locality / non-locality pursuit currently is, I get the overall feeling that progress is being made via the application of ever more insightful tests. :)
Thank God! Finally! I am not a graduate physicist. I just always found physics fascinating, was always good at physics at school and also did my A-levels in physics, but then studied computer science and electrical engineering, so at best a tiny sub-area of physics, but never completely lost my interest. I've seen so many videos on RUclips about Bell's Inequality, all trying to tell me there can't be hidden variables. And I really tried to understand that, but no matter how I tried, in the end I always came to the point that even if everything makes sense what is said there and also everything seems right, the conclusion that proves that there can be no hidden variables, is not comprehensible. Everything else yes, but the conclusion always seemed illogical to me. On the other hand, I have always been convinced that all inexplicable phenomena of quantum mechanics can be explained by the existence of hidden variables. Reality is certainly much less mysterious than we think. The problem is only that we have reached limits where we can no longer look at things simply and therefore have started to look at things purely theoretically and mathematically. But I stick to it, mathematics is not a science and only because one can describe something mathematically, this does not exist in reality.
Math is abstracting reality. If it exists, it can be broken down into numbers. And if one thing is true, then there is a relation that lets us predict the thing again, and even manipulate reality in a forseeable way. It seeks new ways and questions itself inherrently. It is natural science, the missing link between our ability to interpret reality and the cold hard facts outside of our body-chemistry.
@@guyincognito959 Yes but sometimes abstractions take you right out of true reality, take money for example ;-). It's not the fault of math but our inability to jump between understandings at times.
So, do I have this correct: if you have 2 entangled particles, one with +spin and one with -spin, reversing the spin of one ,without measuring it, does not change the other, but the correlation still stands. You just now know that when you measure the spin of one, the other’s spin will match, instead of being opposite. No action at a distance, but knowledge still updates. If I have this correct, this video taught me something. Honestly, Sabine’s always do. But this one was surprising, because I’d never understood it while having known of it for quite a while. If I do have this correct, then thank you Sabine!
PREACH! Well done Sabine. You're about the only person I've seen explain this rather than just regurgitate rhetoric. You can tell you understand it because you were able to explain it clearly and simply.
@@TheDanEdwards You are flipping something. Without the flip both particles, though random, are measured to always be in opposite spin states. With the flip, they're always in the same spin state, though which one is random.
Thank you for your videos. The CHSH explanation showing QM probability 0.85 versus classical max of 0.75 is more straightforward than other Bell inequality explanations, but I wish someone would do an interference simulation (phase shift) showing why pi/4 is the best angle for measurement.
I really hope you make a video about the many-worlds interetation. I was about to take issue with something you said, but I am glad you at least mentionned it. For those wondering: the many-worlds interpretation gives an explanation of quantum mechanics which is both local and deterministic.
She didn’t assume non-determinism, just non-locality or measurement dependence. I am honestly unsure about what she mean by that, and I am wondering if MWI violate measurement independence, or another assumption she used (or the theorem used). This is unfortunate that she didn’t explain.
@@denisbaudouin5979 To the best of my knowledge, it does not violate measurement independence, because in the MWI the wave function never collapses. What we interpret as the collapse of the wave function is us interacting with the environment and experiencing a single branch of the many existing ones. In a sense, the wave function does not collapse, we get projected into a slice of the wave function (or depending on what we mean by "we". We could also say that difference instances of us are projected into each branch). This explanation is local because the process of branching only needs to happen as fast as particles can interact, that is at no more than the speed of light. It is deterministic because all possible outcomes always happen, there is no random process choosing one in particular. In fact, I remember reading a thesis [1] which proves that there exist local-realist explanations to quantum physics. You don't even need to agree with MWI in particular. The fact that there exist local-realist (and even deterministic) explanations to quantum physics should make us discard non-deterministic, non-local theories as bad explanations. [1] Raymond-Robichaud, Paul. PhD Thesis. L'équivalence entre le local-réalisme et le principe de non-signalement
Wouldn't many-worlds kinda have this global hidden variable that says which part of the wave function we're observing? I guess such variable would just be an artifact of assigning some object the role of an observer. If you're gonna model the wave function itself (and not just "what we will see"), then you don't have to keep track of that and everything is back to being local (or just correlated). seems
@@AGoodGuyOnTheInternet Yes, but I am unsure it means measurement independence isn’t violated, because what you will get depend of the branch where you do your measurement (but I am unsure). Anyways, if it doesn’t violate measurement independence, it had to violate another assumption of the theorem, and it can’t be nondeterminism (because it isn’t one of the assumption).
@@AGoodGuyOnTheInternet Your reply got shadowhammered by YT somehow. Probably because of the link (these typically get straight-up removed). When I'm logged in, I can only see your comment ("@denisbaudouin5979 To the best of"…) after I sort the comments by 'newest'. Otherwise I see four replies instead of five.
_Eventually, the goal of developing such a model is to remove the instantaneous measurement update, and hence make it easier to combine quantum mechanics with general relativity._ This sounds kind of similar to Penrose's idea of gravitization of quantum mechanics, where, as it seems to me, the main claim is that the main problem with combining GR with QM is incompleteness of QM. It would be great to hear from you about the approaches of combining GR and QM, and obviously about their problems.
The ONLY problem with combining qm and gr is that no one has the slightest clue as to how gravity can be quantised, nor how it could be that a graviton fits the standard model.
@@aaronperelmuter8433 well Penrose's idea is that we don't really need to quantize gravity, quite the opposite he solves the measurement problem via gravitational interaction between particles. I am not an expert, so probably I wouldn't be able to answer questions regarding this topic. But you can, at least watch some podcasts with him where he tells about his model, it is called an objective collapse model.
I tried searching for Bell's theorem on your channel, but it appears it does not have a video exclusively about Bell's theorem. It would be every enlightening if you can do a video on it.
Hey Sabine Thank you: - That's really good work and insight. I didn't know there were 2 types of non-locality and it helps me understand the concept better. With terms like "Einsteins Spuk (action at a distance)" I was probably misled by all the press releases, thanks. Is it possible that even the quantum researchers who won the Nobel Prize in 2022 did not have this distinction in mind? Suggestion for a new video: - The film "Everything Everywhere All at Once" refers to different physical theories and principles which if I remember correctly, are also discussed in your book "Existential Physics". I think this could lead to a very interesting video if you can show the differences between the film and your book and describe why this is so.
A less mysterious universe is a more pedestrian one. Ah well, walking is good exercise. Thanks for this, it was a good overview. I think it brings together topics previously covered.
While superdeterminism is definitely an interesting idea that should be thoroughly researched, I think it's still a lot more weird than non-local QM. Think about it: to determine that λ=5 the photon either has to somehow "know" what experiment the scientist decided to do (which while technically possible would make our universe *a lot* more logically connected than we usually think), or it has to pass through the whole experiment, and then retroactively decide that λ=5 (i.e. send information to itself back in time that determines which path it would take, which is also technically possible, since all current physical laws are time-reversible, but still really-really weird)
Its actually simpler than that, Sabine has made a video about it. It has to do with the fact that the act of measurement disturbs the photon and changes it. Something that has to do with quantum decoherence if I remember correctly...
Why use anthropomorphic language? The photon needn’t ‘know’ which measurement was made, anymore than a ball needs to ‘know’ how it was thrown after the fact. The difference here is that while the phase of the electromagnetic wave might very well be correlated with the environment and measurement operation, its specific value is considered “unphysical” in QM, as only the relative phase between the system and surroundings can be measured from a given basis.
@@otinane89 Yup, watched that video, it doesn't work like that. The problem is not with the photon that is measured "first", but with the entangled photon, that either has to be disturbed non-locally (classic QM), or that entangled photon already had the information about the measurement that researcher would make on the other end (superdeterminism). Both are pretty weird
@@anywallsocket Except that under superdeterminism photon's state is correlated with the measurement that scientist makes *in the future*, and that's the problem. So either photon literally analyzed (yes, in an antropomorphic way) scientist's brain and predicted what they'd do in the future (pretty wild, yes, technically possible, but very-very weird if that were the case), or it received a "message" from the future when it was actually measured. Also, sorry, but what does the phase of the wave have to do with this? Deterministic wave phase also counts as a hidden variable, and is ruled out by Bell's theorem, so the only ways out are classic non-local QM and superdeterminism with retrocausality
@@silentobserver3433 the phase, as I said, is meaningless alone, and thus is a non-local ‘hidden variable’ (property of the system-environment relation), and therefore not limited by Bell’s no-go theorem. Also yes superdeterminism implies time symmetry, and thus a kind of timelessness, so backwards and forwards action cannot be distinguished. So whether the ball knows how it’s been thrown or knows how it’ll be caught is the same thing. However this is naive as it cannot explain our obvious experiential sense of time asymmetry of ‘flow’.
Thank you for this awesome explanation! After watching a few videos on this subject I have to say this one was the clearest to me, which might be saying something considering my limited background in physics. It always seemed to me that 'entanglement' wasn't really spooky action at a distance and that the only thing truly spooky was local ... between our ears
You can't affect far away states locally, even in quantum mechanics. I have no idea why she says quantum mechanics is nonlocal. I don't have a PhD in physics, but I studied physics. There was never a reason for nonlocality. There is an error at 15:34: One wave function represents A = +1 and B = -1 and the other A = -1 and B = +1 (due to conservation laws). The wave function as a whole moves to A and B. But she has split the wave function into two parts, one moving to A and one to B. That's wrong! Every type of particle has one wave function. Often that doesn't matter, except when it does matter, as we've seen here. And yes, some parts of the wave function can no longer communicate with each other, but it's still necessary to treat them as one wave function to obey conservation laws.
I think you *might* be missing the point on that. The entire point is "if they are still one wave function", the idea is how can one wave function exist over non-local space. If it's simply nature keeping track of this single wave function "behind the scenes" then that in effect describes the hidden variable idea. But if it's not, then the wave function itself becomes non-local, so thus QM is also non local.
@@aggies11 You got it 100% wrong. There are NO wave functions in nature at all. A wave function is an abstract human construct that makes statements about a hypothetical infinite repetition of the same experiment. Such an infinite repetition does not exist. Technically one can not even repeat the exact same experiment twice. One can only repeat a similar experiment a finite number of times. We can construct histograms from the outcomes of those repetitions and then we can give you a predictive formula that estimates the statistics in those histograms. Nothing in this procedure suggests that nature calculates that formula at all. Since the wave function is therefor not an actual physical phenomenon it can not be local or non-local to begin with. The correct term to use here is "non-separable" and it refers to states like an entangled spin state. Separability is a purely mathematical property that lives in Hilbert space.
Explained so incisively and with a great sense of humor. I watched this video seeking inspiration for how to explain these phenomena to others, and this was perfect. Thanks, Sabine!
@@carlhitchon1009 Well, I would say a somewhat technical definition would be that kinematical degrees of freedom of a system constrained by symmetries that do not depend on measurement like Lorentz invariance/covariance are a good example of quantities that are measurement independent. For example, the proper length of a massive particle traced in static Minkowski space, its invariant square contracted momentum, etc. These quantities should share the quality that the values do not depend on one's choice of frame of reference or how one attempts to go about measuring the quantity. A counterexample of a quantity that is not measurement independent is an object's velocity. Or the relativity of simultaneity phenomenon. Also, dynamical degrees of freedom (independent characteristic properties of a system, such as the components of the electromagnetic vector potential after choice of a gauge) can depend on one's choice of point of view (choice of gauge etc.) but are still generally ingredients of measurement-independent quantities (contraction of the field strength tensor etc.) A good way to identify measurement-independent quantities would be to take note of the continuous parameter transformation properties of the Lagrangian that symmetrically leave the equations of motion of the degrees of freedom invariant, which correspond to conserved quantities via Noether's Theorem. For example, the charge of an electron integrated over all of space is a measurement independent quantity. If I were to try to explain to my grandmother (hypothetically, RIP) what a measurement independent quantity is, I would say that it is like the string of Bingo draws announced by the judge, but a measurement-dependent quantity would be whether this string corresponded to a Bingo on their card - for someone this will be the case but for all others it won't be. (Analogy to the Target Rest Frame - only one observer claims the object of interest is not translating through space.)
Sabine is totally wrong about the existence of measurement-dependent hidden variable theories; in fact, we can always conceive of new kinds of experiments, which implies that a new measurement-dependent hidden variable theory would be necessary for every new experiment, precisely because the hidden variable must depend on the kind of measurement we do. Therefore, such a theory would have no predictive value, but would only be an "ad hoc" justification of already known empirical results. Such a theory would therefore not be falsifiable, and consequently it would not be a scientific theory in any way. In practice, stating that reality can only be described through a measurement dependant hidden variable throry is equivalent to stating that the existence of a scientific theory capable of predicting new phenomena is impossible. This contrasts with the predictive ability of quantum physics, systematically confirmed by countless experiments.
First, she reported, she did not make a statement pros and cons. Second, in my opinion, quantum physics has given up, solving the measurement problem, by the postulate of non-locality as a fact. Every fresh appproach or speculation is worth to be taken seriously
@@Thomas-gk42 You simply ignored my arguments and my arguments prove you wrong. Measurement-dependent hidden variable theories are not falsiable and therefore they are not scietific theories whatsoever; this is why they are not to be taken seriously. At minute 19 of her video, Sabine gives an example of how a measurement-dependent hidden variable theory might adddress the problem of interference. Essentially, you just postulate that there is something we don't know about (a hidden variable) that makes things happen the way we observe them happening. This is not scientific at all and is equivalent to say "we just don't" know". Conversely, quantum mechanics has strong predictive power and has provided many predictions that have been systematically confirmed.
@@marcobiagini1878 Well, I don't see the predictive power, you have a wave function and a 'mysterious' measurement, that isn't a physical process, although you deal with physical objects like measurement instruments. They are not part of quantum physics, but you need them, to describe reality. That shows, that it's an incomplete theory. You say, hidden variables are untestable and therefore unscientific, but I know, that some brave scientists like Sabine made suggestions to proof it wrong or right. Why weren't these things done? Sounds like scientific inquisition for me.
@@marcobiagini1878 You talk like you don't know what science is even about. Imagine one day we get something wrong and stop trying to look at the right direction... Things can get very complex in the future and if we totally ignore things we may lose track of where we failed. A real scientist would never believe something 100%, I understand some things may have a higher probability of being right, but just that.
I’m so glad I’ve discovered your channel! You are so engaging and insightful. I love your style. I can’t wait to obsessively watch all of your videos in detail (skip back 20seconds after having my own thoughts and getting distracted and didn’t want to miss a word). 👩🏽🎓👩🏽💻🫶🏽🤘🏽
The explanation of entanglement using closed envelopes is easy to understand, misleading, and wrong. We consider twin photon pairs. If P1 goes through a 0° polarizer, P2 also goes through a 0° polarizer (perpendicular position). Now, we assume that the photons, when they are created, are aware of their behavior at certain polarizer positions. So, the photons know how to react at certain polarizer positions. (transmission or absorption) Any given photon then has a certain probability of passing through a polarizer at 0° and 30°: W(T(0°), T(30°)) Now, we extend the term by another condition: Response at polarizer = 60°. So that the probability does not change, we consider both possibilities: W(T(0°), T(30°)) = W(T(0°), T(30°), T(60°) ) + W(T(0°), T(30°), A(60°) ) Now, we omit one restricting possibility on the right side: W(T(0°), T(30°))
It's interesting that in the physics community so many people just brush these issues under the rug. Of course it can't go unnoticed after last year's Nobel Prize, but you do a great job by reminding us about it and explaining it to the general public (although as you stated at the end, you need to be familiar with some basic concepts of quantum mechanics in order to understand it.)
@@alterego3734 There really are no realistic issues, this claim of super-determinism/measurement independence is on the order of "But if every particle contains a supercomputer with enough memory to store all of future space-time, and calculate its future interactions with every other particle before the interactions occur, then they could give the observed measurements in our labs! Much more likely than RNG in the natural world, right?". I mean, sure, that's a possibility (?), but maybe it's fair to discard it as absurd? (Which is what Sabine refers to when claiming that the physics community discards the idea). If there's an experiment that can verify that measurement independence can't be trusted, I'd receive the greatest mind blow of all time and it would be amazing to be proven wrong along with most of physics. It sounds hard (impossible?) though to construct a test to check if the particles are conspiring against us when we try to measure them, by measuring them...
No its not that. I think its more that for most physicists working with quantum mechanics they don't actually care what it means in terms of describing reality. Its irrelevant to them, so isn't a topic for discussion. All the matters is what the maths says, what that means for reality can be left to philosophers.
@@chalichaligha3234 physics is stalling, yes, but I dont know if I fully agree this is the reason why physics has stalled. Quantum mechanics has lead to very real practical applications. It doesn't matter whether that means we know in a multiverse or not. Theres no way of finding out anyway, which is why its a question for philosophy. Physics is not philosophy.
I think I'd like some info on how it's possible to change a particle's state without measuring it - the only part of the video I didn't really get. It's probably super easy once you explain it, but that's exactly why I'd like a video on it~
if I'm not mistaken you can affect a particle in a random way, like going through a perpendicular magnetic field that will spin the particle 90 degrees in a random direction. you don't know what direction the particle is spinning, but you know you changed it because it has to align with the magnetic field either spin up or down.
@@SergioBallestrero Thank you! The other reply from ArtisanTony didn't really convince me because I remembered Sabine talking about how it's a misconception that only human-made detectors can "measure" things, (I think that was in her Superdeterminism video) but this seems understandable.
Excellent Sabine. It’s indeed curious that physicists keep ignoring this second interpretation. I am not a physicist, my research is on AI which focuses very strongly on building models. It seems to me physicists keep thinking that the models of physics are really the physics and not a model. It seems to me that they confound map with the territory, and they keep stating that physics are uncertain in itself instead of the model having uncertainties.
Physics is (not are) uncertain, some guy called Heisenberg has a principle name after him. It’s called the uncertainty principle, you may have heard of it before? It refers to physical reality, not models of reality.
@@aaronperelmuter8433 The Heisenberg Uncertainty Principle talks about the commutator of two operators. It's a model whether you ascribe ontological status to these operators.
The distance between two points is change in possibility. You need to disconnect from A to emerge at B. Its why A divided by zero equals NOT A (a set unrelated to A except at superposition) you need to stop interacting with A to be able to interact with B..
@@dingo4530 haha don't worry, I don't care about your gamer cred. I don't even know you. But like with quantum entanglement, misinformation needs to be corrected. 😉
When Sabine said, “You’ve already watched 20 videos on Bell’s theorem and they didn’t help,” I felt that.
I have, and it hadn't 😂
@@DavidG2P Same, man. Same.
So accurate
They usually claim and state a lot, but when one takes the time to think and verify, one finds a contradiction, logical fellacy or incompletedness... like the makers of those videos don't know themselves what is actually meant and why it worked that way.
When I looked at the Bell's theorem discussion the last time, it started out by:
- Einstein claiming hidden variables
- another guy saying hidden variables would violate blahbla
- third guy proving blahbla is violated
- fourth guy saying violation proves Einsteins claim wrong.
I invested a lot of time determining what was wrong and came to the same conclsuion Sabine did.
@@skeltek7487erhaps this difficulty that we're experiencing is the same as physicists lol. I bet even they are basically believing what they want to believe at this point. Simply because quantum mechanics is such a complete mystery. So much theories postulated but over time, only a few of them are actually proven.
I usually only understand about 50% of deep physics, but I like that your videos help nudge that percentage up to 50.1% with a 0.1% error margin either way.
Clever
@@rsh650 "Physics" is...physics. "Deep" is the depression you have when you see you can´t understand half of it.
@@purpleman1974 this comment is indeed very deep
I kind of half understand about 5% but only if there are diagrams. But I keep coming back because her videos are the wildest thing you can experience this side of the Controlled Substances Act!
This is self-deception. If you offer any listener here the most elementary problem, not one of them will even find the right way to solve it, let alone the solution as such.
For all the math people out there, locality is sort of the physics version of the Intermediate Value Theorem, which states that for a continuous graph, if it passes through point A and B with coordinates (x1, y1) and (x2, y2), respectively, the graph has to go through every point in between. So locality is if the the graph is continuous and non-locality is if the graph is non-continuous, meaning it doesn’t have to pass through any of the points in between
Very useful...thanks !
And yet a ‘continuous’ spacetime is only macroscopically valid, so we might need a discrete definition of local causality as well. However, it might be necessarily probabilistic, such as ‘nature is most likely to act from A to B along the path of least edges’.
Yes! So if QM ppl things reality is non-local, then the first thing they shud do is to reproduce entire QM without calculus. Or, they shud shut up about shut up and calculate.
@@anywallsocket Only if you assume Relativity is wrong and Quantum Physics is right. Space-Time might be continuous and there might be Hidden Variables, and the lumpiness of Quantum Physics is a flaw, a limitation. If my friend, Prof Tako, is right, we might have a new theorem on this. It's a modification of Bell's Theorem, called...
@@anywallsocketo one knows this. Some Quantum Physicists only erroniously claim this. Yet they never managed to demonstrate "non-continuous" nature of space-time. Rather the fact that the speed of light is same for all wavelength and actually for all massless particle is a rather strong evidence that space-time is most likely continous.
Quantum mechanics and Artificial Intelligence is being taught to the general public by journalists. It's no wonder it seems like no one understands either.
The fact u cant discern a physicist from a journalist tells me all i need to know here...
I did my master's degree on artificial neural networks. Believe me when I say that computer scientists don't understand AI either. (I'm very serious; we have quite a limited grasp of the emergent processes that occur within deep neural networks, such that interpreting them is an entire field of academic study.)
@@wesgeiger2037 He's not talking about Sabine
Brian Green doesn't help much either.
Anyone that does real science understands that it boils down to FAFO. Just with a limited scope and schedule.
This was some of your best work Sabine! Apparently making peoples brains hurt and making them laugh at the same time is just what science education needs. Why the Profs thought they could be dry as an old biscuit and expect people to listen has always been beyond me?? I would've gone to your lectures instead of reading the book. That's a big statement as the book has all the knowledge you need and doesn't expect you to get out of bed or even wear pants!
Quantum Mechanics is a self telling joke and laughably stupid no clown or comedian required
@@off6848 "Tell me you didn't understand the video without telling me you didn't understand the video."
@@BTFranklin whatever helps you sleep bud
if the spin of a particle is measured , then it is flipped , why should it be measured again?
@@BTFranklin 🤣💯
Thanks a lot for this great work
Many thanks from the entire team!
The guys who proved the violation of Bell‘s inequality won the No-Bell Prize 😂
💀💩💩
Haha there should be a No-Bell prize in the name of Bell for negative results to promote and give recognition to all hard work in experimental science and research, not only "lucky results"
That's one Aspect.
All need a secret before u can experience Jesus healing energy. The Illuminati aka fallen angels aliens NASA what ever you want to call them in there flying tin cans. Can't get out of lower orbit because of the vacuum. Universe is only 77 thousand SQ miles big breathable air through out space angels have to breath. Mars is only 250 miles away sun an moon are much closer an only a acre big. Heaven is on Mars moon that's what all the thrusters are for space x Star ship try to punch through the vacuum and destroy Mars moon heaven. I cleaned out hell left the light's on so no use for hell. I ripped the soul out the devil after he went dragon just to make it a fair fight. Now souls can be destroyed. True compassion for your fellow man is the only way. Now all are allowed black an white sheep to experience Jesus healing energy all old aches and pains will be washed away takes 30 minutes best to relax and shut yr eyes. Or I'm lying an u won't feel a thing
No-Bell for Bell 🔔
I've a Ph.D. in physics, and this is the best explanation of Bell's Inequality I've seen.
I've been physics-curious all my life but didn't pursue it in college because I couldn't understand certain principals. Sabine's animation of the two envelopes and the information within _finally_ made this concept click for me. I kept trying to find some way for the other envelope to "know" instantaneously what the opened one contained. Science writers should watch this video
I'm really interested in physics, but whenever I watch some videos like these it feels like my brain is melting sometimes and I have to rewatch parts, am I just not made for this field?
This makes me feel more intelligent because it convinced me that if I only put a little more effort into it I would be able to understand it all. Obviously I’m not going to put that theory to the test
Wait, what? How does that work, exactly? 🤔 Shouldn’t it make you feel LESS intelligent, rather than more? 😱 Otherwise, why would you need to put in that little bit more effort to understand something? 😳 Or am I missing something here?
@@aaronperelmuter8433Feelin like you’re on the verge of knowing the fundamentals of the universe makes him feel smart, and I feel the same way.. I never fully understand it, but for every video I have a new sentence or two of information that I am able to retain and that adds up
@@aaronperelmuter8433 self delusion is a useful tool to achieve happiness
@@andrewpaulhartI LOVE that magical feeling of incipient understanding; but believing you finally understand something when you don't is not necessarily delusional; you might just be incorrect. True delusion requires believing you are correct even after Sabrina has proven you wrong.
When watching Sabrina's videos, I quite often experience what I call Sabrina's-magical-5-minute-illusion. Her delivery is so logical and her explanations are so elegant that at the end of her video I truly do believe I understand something... for about five minutes.
@@2ndfloorsongs I stand corrected. … therefore better informed, which I’m convinced will contribute to making me more intelligent. It all works out in the end.
19:45 Thank you Sabine! You mentioned the statement "What you measure depends on how you measure it" in a previous video several times, but I've never understood what exactly this is supposed to mean. This time it's clear. Thanks!
Nice one :)
Indeed, a good scientific experiment is one which asks nature a very specific question. If you ask her vague questions you’ll get vague answers.
Great video Sabine. I subscribe to the concept that all of the universe is fundamentally made of pure energy. What we refer to as “particles “ are nothing more than discrete packets of energy and the interactions forming larger complex particles are the result of interactions which form positive feedback loops leading to stability. Obviously this is already the basis of solving the equations which lead to the standard model. However once we threw the statisticians into the mix everything became overly complicated. The statistical studies really apply to the properties of the particles and not so much the fundamental existence of the particle. Here we are talking about information. It is observation that is probabilistic, not the particles themselves nor their actual properties. It is the forcing of our perception into the equations which has lead to the proliferation of statistical analysis and information theory. I hold that reality is all deterministic and based solely on perturbations in energy fields which can collapse into stable particles when they are in the state of positive feedback. Interactions of particles are again the process of recombining into a new positive feedback state. All this other gobbledygook is fundamentally about our ability to observe this simple phenomenon and not the particles themselves.
Are the hidden variables already determined before the measurement?
@@wiesawnykiel1348 I think so, just as they were in Dr Sabine's envelopes. The point of having hidden variables, that are real but about which we are ignorant, is that particles don't have to affect each other instantaneously.
The ideas of explaining non-locality with portals, the lightcone, the graphics and the entry and exit arrows are magnificient.
but a line is the shortest length between 2 points, which can be through a portal, locality itself is relative
@@Xerion404 Right - if you happen to have a wormhole handy, otherwise not so much.
Listening to Sabine I wish I could forget all the incorrect information I have listened to in my 70 years. Conditioning is a real problem as your brain keeps going back to the old patterns. Thanks for the videos. I am slowly getting a better picture…. from a person with an Arts degree. Love the dry humour as well🇨🇦
Don't let @schmetterling4477 catch this comment or you will get roasted about how there has been no misinformation by physicists and all of them apparently explain spooky action at a distance just like she does. Physicists don't explain it as two entangled particles actually being able to affect each other from mass distances instantaneously according to him. Apparently they've all been saying what Sabine said in this video the whole time and we have just somehow mistakenly perceived them as saying something else. Again this is according to @schmetterling4477, not me.
Thank You Sabine , … You CONSTANTLY EXPLAIN HOW ALL QUANTUM PERCEPTION IS THE INTER-EXISTENCE OF QUARKS WE ARE ALL COMPOSED OF … PARTING MUON PHOTONS OF LIGHT WITH ALL THE OTHER QUARKS YHWH CAUSED TO EXIST IN THE ENTANGLED BEGINNING OF TIME … more than 20 billion years ago . SO COMPRESSED IS THAT LATTICE , THAT THE MERE PERTURBATION BY ANY THOUGHT EVOKES THAT INSTANTANEOUS ENTANGLEMENT THE GREATEST MINDS CALLED “ SPOOKY “. Bell , pondered it , … Einstein , resisted it , and You , Sabine , ARE IN LOVE WITH THIS MYSTERY . This is Delightful to Watch !
You are GOING TO LOVE THE PERMANENCE THE LORD Creator Elohim , is going to WRAP YOU
CONSERVATIVELY IN …WHEN YOU PERCEIVE YOUR UNLOSEABLE FOREVER , PERMANENT ENTANGLEMENT IN HIM . Ecclesiastes 3:14-15
“ For I know that whatsoever God doeth , it shall be forever ; nothing can be put to it , nor anything taken from it , and God doeth it that all men should fear before Him . For that which is , is the same as that which was , and that which was is the same as that which shall be ; for God requireth that which is past.”
Psalms 36 : 9
“ In Thee , O LORD , is the wellspring of Life , and in Thy Light we shall see Light “ .
Danke Fraulein
The understanding that the invalidation of local hidden variable theories via Bell's Theorem hinges on the assumption of measurement independence is not a new discovery per se, but it's a nuance that's often overlooked or not stressed in many explanations of quantum mechanics. Emphasizing this point can be crucial for two reasons: 1. Clarity and precision in scientific communication, and 2. Expanding the scope of possible solutions. Thank you, Sabine!
ChatGPT
Sabine’s dry humor is hilarious and makes learning complicated physics much more fun. Existential Physics is an awesome book for the same reason.
I love that she delivers absolutely everything at the exact same tone and cadence so it always takes me just a moment to catch that she made a joke, which is so much funnier than somone like Matt O'Dowd (who I also love)
Existential Physics: surprising, excitng, entertaining and hopeful. One of the best books I read in the last 15years.
I like her dry Humor also. But I am dismayed that she is a Materialist-Determinist who is grasping at straws. 'Super-Determinism' and 'Unknown Variables' are the Physicist's version of 'God works in mysterious ways'. Like all Materialist-Determinists she cannot admit that she is wrong and so she wants everyone to ignore the centurys worth of experiments in Quantum Mechanics and accept that we just don't understand 'God'.
I enjoy Sabrina’s teaching style as well
@@augustadawber4378 I look forward to reading your published results on the topic.
I've been waiting for this video since the 2022 Nobel Prize was announced. Sabine did not disappoint, perfectly summarized.
Precisely when you said "wow, you are still with me, so glad you haven't left," I was thinking that this video should win sort of educational award. It's shockingly informative.
i was literally thinking to myself "this is the point where I'm starting to not understand, so I need to leave" and then she says that immediately as I thought that.
I was recently attending a course where the professor stressed that if you let go of the assumption of measurement independence, all problems go away (and you are a super determinist). So there's at least some physicists acknowledging this to their students.
Quantum measurements are anti information, in the sense that they partially destroy the quantity being measured.
The implication being, no measurement can physically be made without producing uncertainty.
One framing of the problem is to drop the assumption of measurement independence, another way to frame it is to add the assumption of fundamental non determinism. Non determinism must be in the observation, because the observer produced it!
Measurement independence is a demonstration of why perfect information in the universe is a paradoxical concept. It's not just scientists that fail the measurement independence test, fundamental particles do the same.
Consequently, variations of determinism that posit perfect information in the universe should be abandoned. They're potentially descriptive, but not predictive. All our predictions now take the form of probabilities that account for uncertainty. As it should be.
As a non determinist that thinks the universe emerges from noise, it seems to me that the strength of quantum mechanics is that it embraces and describes non deterministic physical processes, in a way that even determinists must accept.
@@ywtcc Team RNG let's goo!
(the concept of all these complex structures, life etc emerging from random noise is just the coolest thing ever to me!)
@jamesnicholl4730 - But even though the collapse is fundamentally random, it is still heavily weighted to certain outcomes. I like to think if it as determinism by large numbers, if you get what I mean. Over time, you will get the most likely outcome repeated over and over, so it still looks deterministic because of the statistical probabilities
@ElectronFieldPulse Couldn't have said it better. Just wanted to point out the fundamental non-determinism, it is the only way we know of to create truly random numbers.
@@ywtcc it's like trying to measure the speed of a car by hitting with another car
As a 4th year physics major who just finished my last (*undergrad* upper division) quantum mechanics class, this is such a great comprehensive video! Wish it had been out while I took my class in the spring 😂 would’ve helped in the discussion of non locality
think of as AM FM radio. If you set the antenna to a particular voltage transmission, you can compose a message by modulating the repetition frequency of this particular voltage on and off, which is how Amplitude-Modulation radio works, tuning, listening to the repetition differences of a particular voltage.
If you set the antenna to vibrate with a particular repetition frequency, you can compose a message by modulating the intensity of the voltage higher or lower, which is how Frequency-Modulation radio works, tuning, listening to the voltage differences of a particular frequency repetition.
This means, beyond any mechanical physical properties interactions, the Universe fundamentally have two formal ways to act non-locally, either by tuning to a voltage (charge) intensity amplitude, listening to a bandwidth range of frequencies, or by tuning on a vibration (pulse) repetition frequency, listening to a sequence of different intensity amplitudes.
Which makes of, understanding all of these, to really question the very basic needs of quantum wave, and particles interpretations. Good night. Have fun, Anna. Let's not break the collapsing function.
(note: Yes, you cannot do anything at speeds faster than light, but yes, you can do anything in space at light-speed. You will figure this out.)
I am confused? What is measurement independance?
@@WackyJackyTracky The part about Measurement Independence 16:34 needs its own video.
@@WackyJackyTracky At a certain degree beyond applied sciences, tenured researchers and professors are just twirling their thumbs and fingers... until they feet their stomachs growling and then they go eat.
In other words, it's mostly "clever" linguistic BS.
Oh, they know "real math" and such. But sound math, sound astronomy, sound physics, etc. aren't really involved in these nonsense (eg., "string theory" and how it's gonna usher in the next phase of science, "what's going on inside a black hole," what IMAGINARY things, particles, energy like "dark matter," "dark energy," etc are or are made of...)
Us, little, uneducated people questioning these "string theory experts" and such is like farmers of Classical Greece questioning Greeks' "most learned scholars," asking them to explain what they meant when they said "the world is made of FIRE, EARTH, WATER, AND AIR.
The answer, then, would have been: Oh, you poor souls... you have neither education or natural intellect to understand deep things like these. You should just put your head down and farm and leave the deep thinking and real science to the really learned ones...
Today, you ask what "Dark Matter" or "Dark Energy" is... ZERO of these guys who have graduated at the top of their classes from Caltech, MIT, Princeton, Cambridge, Oxford, etc. in the last 50 years.... know ANY CONCRETE idea or detail of what they are talking about. But they swear up and down their "Ivy Tower" corridors they've found the deepest BS.
Remember, in the early 1900s (when crazy Fritz Zwicky first came up with this "dark matter" BS, when Hubble was still trying to see of Andromeda was another galaxy or just a smutch of the Milky Way)... the "best and brightest" people like Sir Arthur Eddington had declared he and a few other deep intellectuals HAD already discovered all there's to know about the Universe... only post docs were needed to work out the tiny, less important details.
Remember, that kind of BS, again, has been going on since BEFORE the Rise of Athens. And, again, early 1900s, the Milky Way was the only known galaxy in the Cosmos... and these crazies had already declared they knew everything on earth and in the Universe!
By the late 1990s, too, remember.... 100% of the "best and brightest" in SCIENCE (astronomers, mathematicians, cosmologists, etc) were 100% sure the Universe was SLOWING DOWN... and poorly paid post docs, again, simply needed to work out the exact rate of deceleration...
And this was NOT a very complex issue, compared to some others... as it was a binary situation: yes-no, true-not-true, accelerating-decelerating, etc. And virtually 100% of them got it wrong, when the average, random person on the street had a 50-50% probability of getting it right...
ALL THIS is to say:
Take most of these "deep stuff" with a very healthy amount of potassium salt: ----- "Planet Vulcan".... "ether".... "universe is not as you think it is".... "dark matter" .... "dark energy" .... "string theory" .... "quantum loop theory".... "inflation" .... "super-inflation".... Jesus/Dad & Uncle Allah vs. their former Archangels now known as Satan, Lucifer, the Devil.... "time ticked SLOWER at the beginning of birth of space-time/the Cosmos".... "the Cosmos has no center, because everywhere exactly the same... everywhere started at the same time and while the Cosmos is EXPANDING, it is expanding by CREATING space that was not there seconds before... but we are NOT expanding into nothingness out there," etc.
I giggle silly, when well educated people use THE EARTH as an analogy to explain why or how there's no "center" to it (nor to the Cosmos): yes, there is! The Earth has a CORE and that's its center! It doesn't matter that you "can't find" a certain to earth while floating on a raft in the Pacific Ocean.. but earth DOES have a center to it.... because it is a SPHERICAL object...
And if the Cosmos has a radius, or a diameter (doesn't matter which), of "93B light years" ---- so that, even within the 13.8B of our small patch of it, it is the same in every direction you look --- THEN it has a center to it (even if you have no idea where it is, from your tiny patch of space-time... like someone on a raft drifting in the ocean, in the Bronze Age, wouldn't know whether Earth had a center or not... because, you never know, it could have a point at some edge, where you "fall off" the face of the earth, as some legends had it...)
It doesn't matter whether space-time is "flat," or it had a "negative" or a "positive" curve to it.... whether it is "spherical" or rectangular or any other shape or structure..... if the Cosmos is SAID to have a 13.8B or a 50B or a 93B or a 500B light year radius/diameter to it... then it has a CENTER to it, even if we will never be able to find it...
@@WackyJackyTracky @WackyJackyTracky first understand they are measuring particle spin, which is actually a charge intensity magnetic momentum angle on a pulsed repetition frequency. Now, after watching @Mavrik9000 answer on this video segment, then, one can infer as a) the energy pulse repetition on the first filter split into two different frequencies with charge of two different magnetic angle, b) after the energy radiation bounce off the two mirrors and pass thru the last filter, it recombines back into its original energy frequency repetition, forcing the magnetic momentum of the carried charge to align back to its original magnetic angle. There one still ask, what happen on the detector A? On the last filter, the radiation energy as it pass thru at different frequency repetition, and charged at distinct magnetic angle but same intensity value (or amplitude), these frequencies interfere on each other creating a bandwidth range of frequencies with magnetic mix angles but a uniform charge. Not the result expected to see in the detector A. Therefore, in principle, the experiment is not a failure, it is actually the concept, the interpretation of "waves" of "particles" for actually energy "pulses" repetition of "charges" intensity.
If I had seen this video in 1981, I'd have an MS in physics today. A beautiful, clear explanation. The papers with +1and -1 are Feynman-esque. Just brilliant.
+1 and -1 = 0 this is zero-sum-math, but our reality is a non-zero-sum-game in energy, biology, industry and security. I bought "The Feynman Lectures" in 1969 and in 2011 the NEW MILLENNIUM Edition. I don't know if i should realy read them or just buy brilliant/Sabine?
Thanks!
The "collapse" of a wave function is simply the terminology used to describe that the equation describing the probabilities of the wave function has been updated to reflect out observations. That explanation was very helpful.
Describing it with more words does not make it valid.
e.g. if the wave function describes a tree of alternative outcomes, and you "update" it, then you're just pruning the tree, making a shape it would never naturally grow into.
@@DavidByrden1 Sabine is a super-determinist, so there isn't a wavefunction-collapse problem for her. But she fails to deal with the implications of super-determinism. All roads lead to insanity.
Kendra- “all roads lead to insanity” sounds like a Werner Herzog documentary
I heard someone describe it as “the moment a wave becomes ‘aware’ of the environment.” But they weren’t suggesting that the wave was conscious.
The collapse of the wave function was a rather ad-hoc invention in the early days of Quantum Mechanics to have a rule at hand for computing measurement outcomes. It doesn't make the general QM descriptions invalid at that particular incident of time. For instance, in decoherence theory, it is possible to follow and describe this kind of "collapse", and in quantum optics and QED, that's possible too.
If I'm not mistaken, there are even remarks on that topic in John von Neumanns old book about quantum mechanics, in the chapters where he describes the interaction of test species system and environment - but I'd have to check that again.
Thank you Sabine for patiently explaining Bell's Inequality in detail, most explanations I have heard have been very difficult to follow.
One of your best yet; very clearly written and delivered, very illuminating. Nice work!
❤❤❤ This video is EXACTLY the right length! OMG I think I finally understand! Holy cow! Yes the statement that "John Bell ...forgot" is blowing my mind, but not because of science. I thank you for the comments you make right after that, because it helped me to be sure that I wasn't nuts and that you didn't misread your script.
I will say this: the word "entangle" seems to be intentionally misleading, no matter which suffixes they use with it. Therefore, whoever first wrote that a particle was "entangled" was lying. YOU are magnificent! And yes I needed help understanding the 2022 Nobel, too. If it were up to me, no physicist would be allowed (by their peers!) to use the mystical-sounding word "entangled."
Thanks in return, much appreciated!
This is one of Sabine's best videos to date. It is an important concept to help refute the "quantum woo" that has become part of our popular culture.
A fellow Science Asylum viewer I see.
As a quantum physicist, I agree with everything she said. BUT - What she failed to emphasize here (although she did in her other video about free will) is that measurement independence is something any sane (typical) person would say must be true if the two measurement locations are separated by thousands of miles (or metres). So, when the three No-Bellists did their experiments with far-separated detectors, it does seem very strange that they see the results they do if one 'believes' in measurement independence at a distance. The more you think about this, the stranger it seems. That is, it is impossible to 'understand' how the world can be the way it is. I don't call that thought 'woo,' it is physics and points to a still unclear aspect of the theory called the quantum measurement problem. Google that if you like.
Its still quantum woo. Her envelope analogy is incorrect.
A proper analogy would be to put +1 and -1 in one envelope, and the same in the other envelope. Remember, they are in both states at the same time.
When Alice opens her envelope, its -1, and John’s is +1.
That’s very weird.
@@astrumimitari7467 Is her analogy truly incorrect? Wouldn't placing both a +1 and a -1 in each envelope equate to placing two particles in each envelope? This is simply the left-or-right shoe analogy other physicists use to describe entanglement, albeit with different names for the parts. Or is that frequently-used analogy also incorrect?
@@fantalimon1454 No, not two particles in each envelope necessarily. I mean yes, but each particle is in two states. The +1 and -1 are not particles, they are states of the particle. Since each particle, before measurement, is in two states at the same time, then those two states need to go in each envelope.
Two unmeasured particles have 4 states.
Thank you, Sabine! I wish someone had told me this in those terms 20 years ago, too.
Hard to follow, hard to swallow. But like always, Sabine does a great job making these kind of interesting topics accessible for non-physicists.
'hard to follow'.... i must admit i'm at an intellectual minimum today... maybe next week ?
@@scene2much There's no shame in rewinding some part several times to gain a sufficient understanding. Had to do it plenty of times. Knowledge is often a challenge against the self.
It's likely fake or something, politically speaking science has become somewhat suspect. The degree=validity system of social interaction only came into existence when the federal government banned employers from ability testing their own prospective employees to help realize the civil rights mandate, companies then used college degrees as the next best costly signal indicating qualities they could no longer test for. Physics ran out of things to do after the Standard Model proved entirely correct and now needs to protect it's considerable financial endowments, it's in a similar situation to Southern Poverty Law Center who have long since defeated the KKK but need to find reasons they're still taking people's money.
Meanwhile I feel for quantum computers what most probably do: There's no one deserving of this power, no good will come from anyone having it. Physics is proving to be more trouble than it's worth, it's theories are either performative falsehoods or a symphony of doom heralding some new way for science to humiliate mankind and endanger continued life on earth. Physics is perhaps best not studied, that will be the majority opinion among even atheists before this woman is even dead probably. The fact the first quantum computers will be used for the surveillance of dissidents is exactly why the human scientific story needs to come to a plateau beyond just mere fearful Luddism.
This is the BEST thing I've learned in years. Thank you! Finally, someone who understands and can explain the problem with Bell's Theorem. Bless you!
Except that it’s not correct. Sabine is wrong. QM is a locally causal theory. It’s hidden variable models that must either be non-local or violate measurement independence.
You learnt some hard concept there. Congrats
@ToddDesiato If you understood what SH said, maybe you could explain to me how it works in the Mach-Zehnder interferometer (from about 16:40). If a photon hits beam splitter 1, does that mean it only has one of two "hidden variables"? Either "hidden variable 1" (then it "reflects") or "hidden variable 3" (then it "transmits")?
@@wiesawnykiel1348 Yes, that is correct.
@@ToddDesiato What if, after leaving beam splitter 1 (the photon had "hidden variable 1" and was reflected from BS1), we insert mirrors and direct the photon at beam splitter 2, which means that interference must occur?
Probably the single best science education video I've ever watched. You're a treasure, Sabine.
l
Indeed this video is a gem!
I still have to chew on some steps, but gives new (to most of us) perspective on an extremely controversial topic, with the only things sure about it that it has been misinterpreted in the vast majority of cases.
nonlocality is real because we can remote viewand have precognition and clairsentience. those things i do all the time and it is more convincing to me than any theory..
Actually mind transcends matter .. i can appear to people remotely . what i dont know is whether i could move objects at a distance. i can appear to move objects and i know if objects are moved at a distance.. i just dont know if i can actually move an object at a distance. i did experience a friend moving an object in my house from a distance. its far more interesting experimenting with reality than theorising.
@@mythtree6348 What watching too much Star Wars will do to a mf
I've already watched about 20 videos on Bell's theorem and your stealth explanation was glorious. Your disambiguation of entanglement and Bell's theorem was eye opening since I among many others, as you mentioned, thought they were concerning the same thing. I 'think' I finally kinda get it without all the 'quantum' hand-waving and also clarifies why Entanglement doesn't seem to be the way for FTL communication. Thank you so much, nothing better than that feeling when you start to 'get' complex topics. Still makes my head spin but in the best possible way.
Now I finally know why "spooky actions on a distance" as It has been described never made any sense to me. Ever since I was a child I thought it was something I didn't understand, but now it's all clear (or at least a bit clearer). Thanks.
Of course every children was worried of "spooky actions on a distance" was a problem that kept me awake at night.
I agree 100% Sabine did an outstanding job explaining this segment. I have heard about entanglement so many times before but it never really clicked until now. Thank you!
@@filosofiahoy4105 I wonder what Einstein had to say about the monster under my bed.
Yes! God doesn't play dice with the universe. It's the universe that plays the dice, while we play God.
You mean that no measurement independence makes sense to you ?😂
This taught me more about quantum mechanics than any video I’ve seen. You are truly talented to make such complex topics understandable for the layman
12:22 Well, it does, in the sense that (you don't mention this but this is very important) the spin measurement is _direction-dependent._ THIS is what makes it so unlike the pair-of-envelopes situation. This again pops up at 15:21, the +1 or -1 spin measurement involves a _choice of direction of this measurement,_ and particle A "knows" the _choice of measurement direction of the spin_ that B had made. But this choice of direction is simply the experimenter B's _choice_ (not an experimental result but an act of B's free will, if you like the word). So _this_ is the big mystery. And Bell's inequality is precisely about quantifying certain probabilities pertaining to those choices of directions of spin measurements. 17:43 I don't think it's as easy as this. AFAICT John Bell's setup is needed to exclude local hidden variables. The Mach-Zehnder setup OTOH involves two measurements (the two half-silvered mirrors) and who is to say the first did not change the hidden variables to make the second mirror always direct the photon to B? Again, I think that this video decided to oversimplify the problem by ignoring the spin-measurement direction dependence which is absolutely _crucial_ to this mystery. (Mathematically, Bell's inequalities are about certain very clever but simple relationships between trig functions of angles between those spin measurement directions.) There is more to say about all this but I need to run some errands now, so maybe later...
Absolutely! The direction of measurement, or some kind of mode of measurement is ESSENTIAL for Bell's inequality. It means nothing without it, and would say nothing otherwise; abosolute zilch. I watched all this...waiting for mentioning why this is NOT a pair of envelopes. Unless is (uh...excuse an analogy) a pair of envelopes if alice open one 90 degrees to bob's and finds its 50/50 chance of being the opposite of bob's but opening it the same way up, would be 100% chance of opposition.
HMM, well envelopes don't tend to work like that...
So Bell's inequality is about whether this direction mode is determined first or at measurement, not the specific -1 or +1 spin at all!
In an experiment we can assess the total probabilities can't we, not generally the specific -1/+1 spins and it would be not possible to pick out the difference at 0 degrees or 90 degrees, giving the same total probabilities of -1 or +1 for either theory. If we measure inbetween, however we get very different probabilities.
is the number >2 is the question. At 45 degrees we get an answer of more than we expect than with a hidden variable theory*. Its more correlated to the CHOSEN direction at the time of measurement always, so we know along the CHOSEN direction it must satisfy +1 and -1 for each particle....not the potential for any random possibility of +1, or -1 each 50-50 (because in the case of the hidden variable, our measurement doesn't affect outcome, so the direction picked could be the wrong one, the right one, or any angle inbetween because it would have had to be determined first. this simply isn't the case.).
*of course there are OTHER hidden variable theories that fix loopholes...well, wormholes in fact such as ER=EPR?
@@jorgepeterbartonI REALLY don't s e how that analogy proves anything. Imagine the information written on that type of polarized image cards, in which there are two images depending on the angle. Great, so one direction of measurement tells you nothing, because you don't actually know the spin yet, do you?; the other gives you precise information on the spin of one, so you can logically deduce the other's.
Thanks! I really dont understand why Sabine doesnt mention this point. It seems proposal.
@@TheDude-w5lthats not the point to “deduce” the other information. If was this point, so is very obviously and no mistery. The point is. The particule DOESNT have the information until you measure it, they have both. You can see the bells theorem probabilitys and see that the wich info that the particule already has the opposite information of the other after the measurement doesnt applies to lab. Please see this experiment in videos. For some way, seems that measuring the entaglement particule affects the other particule, this is CLEAR in studies.
Its not like, all right, this particule has +1 so of course, the other has -1. Its NOT this point!!
Using your example, you can study more in the way that: If the particule has both infos, when you measure it it has info A. How the other particule, that has BOTH infos until you measure it, instantaneosly show the info opposit? No matter how long in distances they are, the entaglemnt particule are affected by the messure of the other! Again, affected by measure of the other….
Thank you Dr. Sabina. Thank you so much for explaining Bell's theorem so effortlessly. Your work and efforts are invaluable. You are a jewel!!
You would be advised to look up Professor Jean Bricmont's numerous youtube talks on Bell's Inequality. Here is his response to Sabine: Jean Bricmont
Ok here is my response (you may post it):
I am not sure that SH really understands what statistical independence means (although other people have already tried to explain it to her).
To quote S. Goldstein, T. Norsen, D.V. Tausk and N. Zangh\`{\i}:
Bell's theorem, {\it Scholarpedia} 6(10): 8378 (2011) (which is quoted in my book Making sense of QM):
``if you are performing a drug versus placebo clinical trial, then you have to select some group of patients to get the drug and some group of patients to get the placebo." But for that to work, you have to assume ``that the method of selection is independent of whatever characteristics those patients might have that might influence how they react to the drug". If, by accident, the people to whom the placebo is given were exactly those that are cured spontaneously, while those to whom the drug is given are so sick that the drug has little effect on them, then of course the study would be biased. And no matter how ``random" the chosen sample is, this will always remain a logical possibility.
This is an example of what is called statistical independence. But the same sort of assumptions is used throughout science.
Turning to the EPR-Bell experiment, statistical independence means that the properties of the incoming particles (electrons or photons) are independent of the direction in which their spin or polarization will be « measured »; but since the latter can be chosen in an arbitrary way (by random number generators, by the digits of pi, by the letters in the Bible or the analects or by the evenness of the number of stars in a portion of the sky) even when the particles are in flight, denying , statistical independence means that one assumes incredible correlations between the properties of the incoming particles and not only the method used to choose the direction in which the spin or polarization will be « measured », but also with the properties of the random number generators, of the digits of pi, of the letters in the Bible or the analects, of the evenness of the number of stars in a portion of the sky or of any other system used to make that choice.
This is the same problem as the one with the placebo mentioned above, only much much bigger.
Some people think that what SH assumes is just universal determinism, à la Laplace. But no! She is assuming very subtle correlations whose existence does not follow from mere determinism. For example, one can say that there is no correlation between the amount of rice produced in China and the number of car accidents in France, in a given time period, even though both are determined (in a deterministic universe) by the initial conditions of the universe and one can multiply such examples ad infinitum.
In fact, if one accepts the correlations that SH assumes, one can « save » any superstition one wants. Take astrology: most of its predictions are never checked, but when they are (taken at random) they usually fail. But one might argue, à la SH, that there is a subtle correlation between the fact of checking an astrological prediction and its veracity, so that all astrological predictions are true except the ones one checks.
In the end, SH assumption is no different from the Duhem-Quine thesis in philosophy of science: any theory can be held true if one is willing to make sufficiently ad hoc assumptions in one’s system.
So there is nothing new here and Bell’s inequality and its verification do prove the existence of actions at a distance, at least according to normal scientific reasoning.
Best,
Jean
I don't know this guy you are talking about, but violating statistical independence, doesn't mean there is a magical process that correlates the settings of the measuring devices with the results. In the example you gave, the settings of the random number generator function *literally* are "incredibly" correlated with the results of where the placebo is distributed. The settings literally decide where the placebo is distributed, deterministically. There is no reason why this couldn't also happen in a quantum experiment, between the settings of the measuring device and the collapsing.
@@giorgosg4032 Quantum Physics Professor Jean Bricmont (expert on Bell's Inequality): "The mere assumption that there are pre-existing values leads to a contradiction when one takes into account the statistics of the results when the directions are different....But nevertheless, some action at a distance does take place" History of Quantum Mechanics or the Comedy of Errors (Published by International Journal of Quantum Foundations on March 28, 2017, Volume 3, Issue 2, pages 31-64) by Quantum physics Professor Jean BRICMONT: "The goal of this paper is to explain how the views of Albert Einstein, John Bell and others, about nonlocality and the conceptual issues raised by quantum mechanics, have been rather systematically misunderstood by the majority of physicists...In any case, refusing to face a problem is not the same thing as solving it. One thing is certain: nobody has yet proposed a local explanation for those perfect correlations, and indeed nobody could do so, since Bell has shown that it is impossible. quoting from S. Goldstein, T. Norsen, D.V. Tausk and N. Zangh`ı: Bell’s theorem, Scholarpedia
6(10): 8378 (2011) note 14: J. S. Bell, Bertlmann's socks and the nature of reality, 1980, available online, reprinted in J. S. Bell, Speakable and unspeakable in quantum mechanics, Cambridge, 2004, p. 149-150 (p. 10 in the online version), emphasis in the original. John Bell quote (also quoted by Bricmont):
"Let us summarize once again the logic that leads to the impasse. The EPRB correlations are such that the result of the experiment on one side immediately foretells that on the other, whenever the analyzers happen to be parallel. If we do not accept the intervention on one side as a causal influence on the other, we seem obliged to admit that the results on both sides are determined in advance anyway, independently of the intervention on the other side, by signals from the source and by the local magnet setting. But this has implications for non-parallel settings which conflict with those of quantum mechanics. So we cannot dismiss intervention on one side as a causal influence on the other."
Back to quantum physics Professor Jean Bricmont:
"Finally, one should emphasize that Einstein’s speculations, which looked purely
philosophical or even “metaphysical” to many, have led to what is probably “the most profound discovery of science”, to use Henri Stapp’s apt phrase [62, p. 271], namely the existence of nonlocal effects in the world. And the EPR and Bell papers laid the foundation for the quantum information revolution. This should be a lesson for “pragmatists”.
Professor Jean Bricmont - Bell and nonlocality lecture posted on youtube channel (see below) "each side sees a perfectly random sequence...whatever the measurements are, that's true...But, if each person tells the other what measurement they've made WITHOUT telling the result... Then they both know which result has been made on the other side...which is some form of information, of joint information....some sort of nonlocal transmission of information has taken place."
2.2K views 10 years ago Quantum Theory without Observers III - Talks
This is a talk held at the conference "Quantum Theory without Observers III" (ZiF, Bielefeld, 22.04.-26.04.2013).
see also on youtube: Jean Bricmont, Université Catholique de Louvain talk
What Did Bell Really Say? 2014 Metaphysics Within and Without Physics Conference June 7-8, 2014, Western University, posted on Rotman Institute of Philosophy youtube channel and
Jean Bricmont: Einstein, Rosen, Podolsky (EPR), Bell and Nonlocality 3 years ago Summer School on Paradoxes in Quantum Physics
Summer School on Paradoxes in Quantum Physics
September 1-6, 2019 posted on John Bell Institute youtube channel
So Bricmont explains the de Broglie-Bohm Theory gives the rational complemention of Bell's Inequality nonlocality since it "represents the positions of the particles that exist, independently of whether one “looks” at them or one “measures” them. ...the result of any quantum measurement will be determined beforehand by the quantum state and the configuration of the “mea-
suring device”. ...This is related to (and explains) the nonlocal character of the de Broglie-Bohm theory....This is one of the ways that the action at a
distance manifests itself in the de Broglie-Bohm theory....The fact that the de Broglie-Bohm theory is nonlocal is a quality rather than a defect, since we just showed that any theory accounting for the quantum phenomena must be nonlocal."
Thank you, Sabine! You've done an excellent job of explaining locality and entanglement. I was a bit shaky on this area of my casual interest and self-delusion of understanding the basics of quantum mechanics and you helped me tighten it up a bit more.
0:00: 🌍 The video discusses the concept of locality and its connection to quantum mechanics.
3:32: ! The example of the two envelopes with correlated numbers demonstrates non-local descriptions of reality.
7:18: 🔬 Quantum mechanics is non-local in nature and the wave function may describe knowledge rather than reality.
18:53: ✅ In quantum mechanics, a photon can take two paths and interfere with itself, but measuring the path requires non-local collapse.
11:25: 🔬 Quantum entanglement does not allow for faster-than-light communication.
15:04: 🔍 The video discusses the non-local causality in quantum mechanics.
22:19: 🔬 The video discusses the non-locality of quantum mechanics and the concept of superdeterminism.
Recap by Tammy AI
No one understands quantum mechanics, (R. P Feynman), but after Sabine's superb presentation, I almost think I can.
Wow! Sabina does it again. The reliance on violation of Bells inequalities always made reality seem more mysterious, unjustifiably so. Eye opening info.
So you think violation of measurement independence is not mysterious ? I suggest you think again
I know Sabine is big on superdeterminism, but I think she underestimates how philosophically repugnant it is to most physicists. That's the real reason most don't take it seriously.
@@jameshart2622 I'm fine with measurements affecting results in some way.. But I'm not fine with that measurement affecting the result of an entangled particle light years away. If I understand it correctly, superdeterminism would imply that the particles somehow knew which measurement was to be made at the time of entanglement.. Thats much harder to bite then non-locality or non-realism.
@@jameshart2622 That's an interesting statement since during the early development of quantum mechanics, one of the things that classical physicists found repugnant about quantum mechanics was that quantum mechanics (in the Copenhagen interpretation) is non-deterministic unlike classical Newtonian mechanics. In the early years of Newtonian mechanics, many philosophers and scientists found the determinism of Newtonian mechanics to be repugnant since it precluded free will, which is what many philosophers and scientists nowadays find repugnant about superdeterminism.
In the 18th and 19th centuries, with the development of thermodynamics and classical statistical mechanics, philosophers and scientists consoled themselves with the fact that since predicting the states of all of the matter, energy, and forces in any given closed system at some time in the future required exact knowledge of the states of all of the matter, energy and forces in that closed system at some time in the past or present, which could not be known exactly by anyone operationally due to practical measurement errors, then the future was operationally not predictable exactly, but through statistical mechanics, it could be predicted statistically.
Those in the free will camp accepted this compromise because it meant that since no individual could predict the past influences on nor the future outcomes of their or others actions exactly, individuals were operationally free to choose their actions even though the actions and outcomes for a collection of individuals could be predicted statistically. Those in the determinism camp accepted this compromise, since mechanics was still fundamentally deterministic if one had all of the necessary exact information.
Development of chaos theory for classical mechanics in the 20th century just reinforced how the measurements of the initial states had to have exactly zero errors in order for the states of many bodied systems to be predictable beyond a certain time in the future without large errors since small errors would grow exponentially with time. Chaos theory was summarized by Edward Lorenz who stated, "Chaos: When the present determines the future, but the approximate present does not approximately determine the future."
I think that the philosophical repugnance of superdeterminism is widespread only among the previous generations of physicists still living because they were indoctrinated with the Copenhagen interpretation of quantum mechanics and the promise of free will through indeterminism in that interpretation of quantum mechanics. The fact that Bell and others at the time did not even realize that measurement independence was an assumption underlying Bell's interpretation of the meaning of his inequalities is evidence of how indoctrinated they were. Even after this tacit assumption was pointed out by Shimony, Horne, and Clauser (1976) about a decade after Bell's proof of his theorem was published in 1966, rather than questioning this assumption, it was elevated to the status of an axiom.
It should be noted, that there are essentially two ways to reject the measurement independence assumption. One is to suppose a common cause in the past that determines both experimental settings and experimental outcomes, as in the work of Shimony, Horne, and Clauser (1976). This sort of account has been called superdeterminism. Another avenue was suggested by Costa de Beauregard (1977), in a comment on the interchange between Bell and Shimony, Horne, and Clauser. Costa de Beauregard objected that the discussants were disregarding the possibility of retrocausality, a possibility that he had advanced earlier (1976). If causal influence from future to past is admitted, then, even if the settings are regarded as free variables, they could influence the state of the system at the moment of preparation, contravening the assumption that the preparation probability distribution be independent of experimental settings.
In the interchange between Bell and Shimony, Horne, and Clauser mentioned above, Bell makes it clear that no metaphysical hypothesis of experimenters exempt from the laws of physics need be invoked. What is needed is something considerably weaker than the condition that the variables not be determined in the overlap of the backward light cones of the experiments. What is needed is that they be “at least effectively free for the purpose at hand.” Bell argues that a deterministic randomizer that is extraordinarily sensitive to initial conditions would suffice to provide the requisite independence, and that variables of this type may be treated as if they have implications only for events in their future light cones. The upshot of the interchange was substantial agreement between Bell and Shimony, Horne, and Clauser. Shimony, Horne, and Clauser consider the assumption of independence of settings and the state of the particle pairs to be justified, even though relativistic causality does not mandate this independence. Thus, although Shimony, Horne, and Clauser initially questioned the measurement independence assumption, they ended up accepting the assumption as being justified, but not mandated.
As an interesting and somewhat related aside, the many-worlds interpretation of quantum mechanics challenges an assumption of Bell's analysis that is different from the measurement independence assumption. Though it might seem that this goes without saying, Bell's entire analysis is predicated on the assumption that, of the potential outcomes of a given experiment, one and only one occurs, and hence that it makes sense to speak of the outcome of an experiment. The reason that this assumption is worth mentioning is that there is a family of approaches to the interpretation of quantum mechanics, namely, Everettian, or “many-worlds” approaches, and some variants of the relational approach, which hold that all outcomes occur in what are effectively distinct worlds.
The many-worlds interpretation is local and deterministic since it consists of the unitary part of quantum mechanics without collapse of the wavefunction. It can generate correlations that violate a Bell inequality because it violates an implicit assumption by Bell that measurements have a single outcome. In fact, Bell's theorem can be proven in the many-worlds framework from the assumption that a measurement has a single outcome. Therefore a violation of a Bell inequality can be interpreted as a demonstration that measurements have multiple outcomes. (See Deutsch, David; Hayden, Patrick. "Information flow in entangled quantum systems". Proceedings of the Royal Society A. 456 (1999): 1759-1774. and Brown, Harvey R.; Timpson, Christopher G. "Bell on Bell's Theorem: The Changing Face of Nonlocality". In Bell, Mary; Gao, Shan (eds.). Quantum Nonlocality and Reality: 50 years of Bell's theorem. Cambridge University Press. (2016) pp. 91-123.)
I think younger theoretical physicists are willing to at least acknowledge that measurement independence is an assumption that can be questioned rather than an axiom that must be accepted.
Once this happens (and it does seem to be happening now), then the consequences of accepting or rejecting this assumption, and if rejecting this assumption, whether it should be rejected based on superdeterminism or retrocausality, will be worked out by theoretical physicists. Then theoretical and experimental physicists will collaborate on ways to experimentally test this assumption. If acceptance or rejection of this assumption does not lead to testable predictions, then it is not a legitimate constituent of scientific theory, but it is, instead, philosophy and specifically, metaphysics. As such, one may accept or reject a metaphysical belief based on the subjective feelings that it engenders like repugnance or delight, which should be irrelevant in deciding to accept or reject a scientific theory.
In any event, from a historical viewpoint, this is just another chapter in the age old debate between free will and determinism (with the possibly new wrinkle of adding the third choice of retrocausality to the debate). Interestingly, Bell's argument that "a deterministic randomizer that is extraordinarily sensitive to initial conditions would suffice to provide the requisite independence" sounds eerily similar to the compromise between free will and classical determinism engendered by the development of statistical mechanics and reinforced by the development of chaos theory, to which I alluded earlier.
@@jameshart2622 I could be wrong, but in my humble opinion,ones preferred philosophical stance should have no bearing on what direction physics takes. Whether one finds the theories philosophically palatable or not, should have no bearing on physics. Physics is not philosophy.
Wow this was really helpful, thanks for explaining this so clearly. I was curious and was worried that this would be over my head. You presented the info in an interesting way and in an accessible way.
Layman here. Absolutely love your content! Thank you for sharing your journey and knowledge with us.
John Bell himself acknowledged the logical possibility of no measurement independance in his 1980 paper "Bertlmann's socks and the nature of reality". His view was that :" this way of arranging quantum mechanical correlations would be even more mind-boggling than one in which causal chains go faster than light."
So I see it as well, Sabine multiple times says.. yeah non-independence is a thing, but does not explain what it means if you got that route.. (say you do the experiment with different angles to measure spin, what does it mean, its all predetermined and thus independent, what angles you measure, especially if you say use the CMB as source for your "random" decissions.. so its all connected? great way to "rescue" locality having it abolished completely by saying every part knows everyhting anyway)
@@georgelionon9050 Exactly. To quote Bell again, "apparently separate parts of the world would be deeply and conspiratorially entangled"...
@@mahasamatman12 Maybe asking for an interpretation what non-independence actually means, only gets a "shut up and calculate" answer again, okay.. but then nothing gained by this either.
@@mahasamatman12 but they are entangled according to QFT where the electron and EM field are coupled together throughout the universe.
@@BarriosGroupie Sure, but that is not the entanglement Bell is talking about in the above quote. He is talking about the type of mysterious conspiracy that would be needed for the measurement independence to be violated, i.e. for the 2 photons to "know" from the start what Alice and/or Bob will chose to measure.
There was always something about quantum entanglement that didn't sit right with me, but for all these years I couldn't put a finger on exactly what. You explained it in a way that I think I finally get it. Thanks!
if all of qp ever "sat right with you" you didnt understand it. At it's core qp is nonintuitive. Something that tells me this intuitive misunderstanding is common is the inate misunderstanding a lot of people have of wave function collapse. They believe the math has power..that wave colllapse is a "force" as it were. It isnt. The math doesnt determine when you know a particles state. It explains why you didnt have the data before that point. It is explanatory not predictive
@@charlesreid9337 I disagree that measurement and apparent "collapse" is part of quantum physics. Quantum physics is perfectly intuitive as long as you don't insist on wave function collapse.
@@psychohist it requires a lot of education before you realise the universe operates on statistics and it becomes intuitive though. At least for me. I agree about collapse humans gavee a bad tendency to think mathematics cobtrols or creates physics. It doesnt..it predicts it. It helped me a lot when a mathematician described it as an incredibly logical and predictive a language. in sumole algebra you can convert certain questions directly to algebra. In programming languages convert english to math and operations
Very nice video, even though I feel it goes over my head at some points. But trying to explain something complicated to us watchers is very much appreciated Sabine!
Thank you Sabine. I didn’t manage to follow the whole video, but your explanations of wave functions, collapse of wave functions, and entanglement were the most accessible that I have seen or read. They really improved my understanding. 🙏
I love a video that is so beautifully explained that it leaves me absolutely clear on exactly which parts of it I totally failed to understand 😃
Love your presentation style, engaging with the right amount of humour 🥰
19:55 Sabine calling out her own audience absolutely slays me & I'm soooo glad to be here for it 🤣
"... because you've already watched 20 videos about it, and it didn't help"
... more like 200 for me :D
also 16:30: "Wow you're still with me, that's lovely" made me lol-irl.
i had to pause the video just to say how amazing the explanation is!!! i really thought (after watching other videos about entanglement/spooky action at a distance) that doing something to one (entangled) particle changes the other particle.
as i am no physicist i thought i just wasn't able to grasp the concept. but it seems quite logical the way you, Sabine, explain it! thank you so, so much!!!
I never thought i could be capable of both understanding something and completely not understanding that very thing at the same time.
Usually journalists who took an arts course at university
If you don't think you understand quantum mechanics, then you understand quantum mechanics
Its like a law of quantum certainty principle any given moment you can both understand and not understand simultaneously 😂
"Stuporposition"
The duality of the universe strikes again
Thanks for the lesson, Sabine! 😊
And yes, I watched it all and understood it. What probably means I don't understand anything, but... Details. 😬
Stay safe there with your family! 🖖😊
This was really good - but also I am confused about one part. In the letter example, the real determination was made when the letters were sent (even if they were not observed until the letters were opened). My previous understanding (from the double slit experiment and the 3 polarized lens example) was that the actual determination happened latter - ie after the pairs were entangled.
So... could you be more clear? Is the observation just uncovering the correlation that was already decided or did the "decision" happen only once the envelopes were opened. In that case, it would be like sending two blank pieces of paper - and once opened one read "+1" and the other read "-1".
I believe she is saying that physicists are debating that & she believes the correlation happens while the two parts were together. No spooky action at a distance; only hidden variables. The violation of measurement independence gives the impression of blank pages writing the numbers when the envelope was opened. If you want to know more about the violation of measurement independence she suggest you check out the literature on it.
I also got a little lost on the multiple mirror part. I was trying to figure out why the half-reflecting mirrors ended up sending everything to one location. Apparently it had something to do with wavelengths causing the violation of measurement independence.
Sabine is a proponent of the hidden variable interpretation of quantum mechanics, as far as I understand what super-determinism goes for.
Thanks Sabine! I have heard a few physicists mention the measurement independence assumption but they point out experiments in which light from distant quasars is used for randomness and how unlikely it seems that could predetermine a measurement choice. How would you respond?
i want a shot at this question too sry, i believe that sabine thinks the choice was predetermined from the start of time- super determinism
I personally believe the moon is not there unless you look at it.
@@ragevsraid7703 - Measured orbital mechanics says you're wrong, the moon helps to stabilize the earth's orbit.
@@WJV9 of course someone/thing is always measuring the moon
@@ragevsraid7703 You’re wrong, I know for a fact she doesn’t believe that as she’s mentioned it myriad times in many different contexts.
The bottom line is that superdeterminism is a very contentious issue. Most physicists working in this area do not subscribe to this interpretation. I have some colleagues who are actively working in this area, and they certainly do not accept superdeterminism as a preferred explanation for the violations of Bell's inequality.
You are a gem of a presenter and a casual genius. Its a nice mix 😊
As a non-physicist, but simple mathematician, I always struggled with the implication behind Quantum Mechanics and always taken for granted the Hidden Variable theory was not possible, even though it always fascinated me as a concept. After looking a bit into it, it is for me now very obvious that "superdeterminism" is actually a much more interesting explanation for the quantum effects we see. Seems a bit arrogant to think that simply because we cannot know certain things, the world must be governed by randomness. Thank you for your videos, the provide at least some comfort.
Wait, it's arrogant to think that because we can't explain a phenomenon it has to be governed by another law that we might one day discover, but isn't it arrogant to think that we'll never be able to accurately measure the phenomena of the universe on an absolute level because there's randomness?
Exactly what I was just thinking to myself.
Sabine finally convinced me that Superdeterminism probably describes reality in another recent video. It's something I'd struggled with for years and the single point that was making me resist the idea was the fact that it doesn't allow for free will. The reason I had difficulty letting go of the idea of free will is that I'd always believed that was the entire purpose of sentience/consciousness/awareness. So, that's the area I had to focus on and I eventually managed to come up with a reason for the existence of sentience that doesn't involve free will. I won't go into what my conclusions were here... it would take too long, but the point is, I succeeded (btw... the answer is not flattering).
Watching this latest video has only reinforced the case for Superdeterminism in my mind. As difficult as this concept may have been to accept, the alternative is even more out there (spooky indeed!).
I don't have any problem at all with the concept of hidden variables. All it means is that Quantum Mechanics is not a complete description of reality, just as General Relativity isn't a complete description of reality.
General Relativity gives us equations that are very useful for describing the Universe at the scale that we can directly experience and observe (the macro). But what General Relativity describes very well emerges from another level, it does not describe that level at all so it tells us nothing useful about the internal properties of black holes, how the Universe came into being or the quantum world. This is where Quantum Mechanics comes in. QM gives us equations that are very useful for describing the reality that gives rise to the macro world that General Relativity describes but is not useful for describing the world at the macro scale.
I have no difficulty in accepting that QM may be limited in the same way that General Relativity is limited, in that it doesn't describe what underlies the emergent properties of the quantum world (the hidden variables).
I'm very much inclined to believe that, as Sabine suggests here, the wave function describes a feature of our knowledge, not objective reality.
If I toss a coin and let it drop to the floor, what's the chance that it will land heads up?
Most would say 50% (50/50) but this is not so. In reality the chance is either 100% or 0%. There is no in between, it's just that we don't know which value applies before we see the result. Not knowing an answer does not make that answer unknowable. That would be a rather arrogant conclusion, even for me! 😅
@@antonystringfellow5152
I think it is equally, indeed, several times more arrogant to assume that determinism (a theory created by the human mind) is true at some level that we cannot know or be sure of the existence (just assume) than to assume that the universe it has an uncertain nature that escapes our ability to know.
It feels wrong that stuff like the spin of an single particle will correlate with what I try to detect before I decided what to do.
Even if everything is super-deterministic shouldn't that sort of thing be pseudo-random?
@@lubricustheslippery5028 Yes, exactly thats what I am saying to the other of Sabine's videos about superdeterminism. Even if we assume superdeterminism is true, this doesnt solve the problem. Still, on average, you should get random events and not those corelations. Since you are getting those corelations between what you choose to measure and what you end up measuring, then you still have to make some laws that explain those corellations. Otherwise you can disregard all laws, and say that everything derives from superdeterminism.
So given particle A and B are entangled and measuring a property of particle B can lead the collapse of particle A's wave function
Let's say you produce a high number of pairs of such entangled particles, and on one end measure the property of all particles B and on the other direct all particles A through a double slit
Now, will you observe an interference pattern? The collapse of the wave function suggests no. Does this mean you can tell whether the particles B are being observed?
If you stop observing particles B, can you tell that this is the case because the wave function will be upheld and you'll get the interference pattern?
very good explanation, especially pointing out the "hidden" (forgotten, ignored) assumptions, in this case "measurement independence". The best part was your explanation, why it might be that physicists fail to mention a crucial (and not necessarily self-evident) assumption for the "proof" that "QM is non-local".
This was great for me thanks. I studied physics at uni, so was already familiar with the topic. Love your witty, to the point explanations, cheers!
Good explanation and well presented. There is another alternative hypothesis that does not violate locality and still causes the "type 1 non-locality" (as you put it). However, I'm still writing out the maths for it because my calculations don't rely on probabilities and are repeatable and deterministic. So far everything is looking like my hypothesis may be correct. However, after the finalized calculations, I'll have to set up a lab experiment to ensure the idea is accurate. Needless to say, this is a long and expensive project.
Is it wormholes connecting entangled particles?
I'm going to be honest, this sounds like a lot of the perpetual motion machine ideas. I'd love to be proven wrong, but I'm a bit skeptical when you give no information and what goal you have by writing this out.
@@Alexander_Grantwants to have an experiment. Better than most people who come up with their own TOE.
Can anyone ever explain who is the "measurer" and does it have to be a sentient being?
@@reasonerenlightened2456 No. Sentience is irrelevant. Measuring sub atomic particles requires interacting with the system, such as putting energy into the system and seeing what changes, its not possible to observe quantum mechanic as an 'outside observer' and that is the problem. Basically, its not like watching an argument between two people through binoculars, its more like trying to stand in-between two people arguing, your presence will change the dynamic and likely the outcome. So the "act of measuring" will influence the outcome, because it injects new variables into, or changes existing variables in, the system.
Absolutely fantastic and undeniably forceful, your method of logical reasoning to describe logical reasons for needing to be able to actually make the science free of inherent inconsistencies it doesn't require to work. I am not able to even follow everything the first time so that I can then induce the process myself without tripping over my perception and I give this video especially nothing but praise. I hope I can manage to comprehend the lesson on quantum mechanics you put together on Brilliant, I had to stop 3/5 or so through it to regroup as I am recently trying to make up for 20 years of reading the ideas without learning the mathematical foundations underpinning them, and I hope you keep making challenging videos for me to wonder if it's not so, even so; respect.🙃
Thanks so much!! I've thought this while reading about non-locality, but was never really sure if I was correct. There's so much misleading information about this subject that it's truly a shame.
I think I need to re-watch this video several times 😅
Crazy idea: maybe for such complex topics a mini-series would be a better format? 🤔
Try the pause button.
Clearly you missed the advertisement for Brilliant 😂
Nope. Your need more examples of something if you don’t understand.
Can anyone ever explain who is the "measurer" and dose it have to be a sentient being?
Pbs spacetime sort of has the miniseries that you are asking for. But I warn you, you will still end up very confused..
Thanks
This video by far gave me the largest amount of understanding on my path to actually comprehend the problem and Bell's explanation of it. I still don't really feel like I'm there, but I've never felt more confident that it's possible.
I don’t think I’ve learned anything, but this was entertaining, weirdly enough.
I hope people who are genuinely interested in this topic will find it even more insightful and entertaining than I did.
Godspeed!
Unfortunately, no.
I would love to see a video about your "Supermeasured" paper, because the idea that e.g. a photon "knows" what measurement will take place (correlations between hidden variables and measurement settings) seems bizarre, but probabilities arising from the geometry of the statespace seems really intriguing!
*these probabilities arising
That would be the superdeterminism she mentioned at the very end, and she has done at least one video about that before. Basically it amounts to the photon "knowing" what measurement will take place because the measurement was predestined at the moment of the big bang (obviously not actually that simple as that would also be the way classical determinism works and that's not what we need here. Should look up her other video for more info if you want, but that's the superlayman description).
@altrag It's deeply unsatisfying to me to accept the kind of "conspiracy" (scare quotes) needed so that measurements always come out just so, that the physical correlations present at the big bang would translate to correlations in a macroscopic phenomenon like labratory measurement. Even retro-causality seems more plausible!
But the supermeasured paper seems to address this by pushing the correlations to the geometry of the state space (not in the distribution of hidden variables in physical systems), which I'd really like to know more about! But that doesn't seem to be what you're describing.
The supermeasured paper argues (iiuc) that Bell's statistical independence is a much stronger assumption that what it's often interpreted to mean, physical statiscal independence, and shows that the latter can can be satisfied while the former is violated.
I really appreciate these videos. I admire how much patience you have to teach us.
I just finished a Physics degree and still didn't know about the non local and superdeterministic hidden variables interpretations, wow, great video!
Measuring an entangled particle doesn't change the information at another entangled particle, but it DOES collapse the wave function of the other entangled particle. And since particles with collapsed wave functions behave differently than particles with non-collapsed wave functions (as in the double slit experiment), FTL communication is possible. Right? By putting an emitter halfway between a double slit and a detector with the detector very slightly closer), the double slit will change from interference pattern to slit pattern almost instantly when the distant detector is turned on, regardless of the distance between them.
Interesting observation
As painful as this entire locality / non-locality pursuit currently is, I get the overall feeling that progress is being made via the application of ever more insightful tests. :)
This is the best science communication video I've watched in a really really long time. Thank you Sabine!
Thank God! Finally! I am not a graduate physicist. I just always found physics fascinating, was always good at physics at school and also did my A-levels in physics, but then studied computer science and electrical engineering, so at best a tiny sub-area of physics, but never completely lost my interest. I've seen so many videos on RUclips about Bell's Inequality, all trying to tell me there can't be hidden variables. And I really tried to understand that, but no matter how I tried, in the end I always came to the point that even if everything makes sense what is said there and also everything seems right, the conclusion that proves that there can be no hidden variables, is not comprehensible. Everything else yes, but the conclusion always seemed illogical to me. On the other hand, I have always been convinced that all inexplicable phenomena of quantum mechanics can be explained by the existence of hidden variables. Reality is certainly much less mysterious than we think. The problem is only that we have reached limits where we can no longer look at things simply and therefore have started to look at things purely theoretically and mathematically. But I stick to it, mathematics is not a science and only because one can describe something mathematically, this does not exist in reality.
Math is abstracting reality. If it exists, it can be broken down into numbers. And if one thing is true, then there is a relation that lets us predict the thing again, and even manipulate reality in a forseeable way. It seeks new ways and questions itself inherrently.
It is natural science, the missing link between our ability to interpret reality and the cold hard facts outside of our body-chemistry.
@@guyincognito959 Yes but sometimes abstractions take you right out of true reality, take money for example ;-). It's not the fault of math but our inability to jump between understandings at times.
Yep, reality can be described with mathematics. But not all mathematics describes reality.
So, do I have this correct:
if you have 2 entangled particles, one with +spin and one with -spin, reversing the spin of one ,without measuring it, does not change the other, but the correlation still stands. You just now know that when you measure the spin of one, the other’s spin will match, instead of being opposite. No action at a distance, but knowledge still updates.
If I have this correct, this video taught me something. Honestly, Sabine’s always do. But this one was surprising, because I’d never understood it while having known of it for quite a while. If I do have this correct, then thank you Sabine!
PREACH! Well done Sabine. You're about the only person I've seen explain this rather than just regurgitate rhetoric. You can tell you understand it because you were able to explain it clearly and simply.
If you flip the spin on one particle then measure it, what happens to the other entangled particle? Does it’s spin also flip, or does nothing happen?
The spin of the other particle does not flip.
Shorter answer: you're not flipping anything. You don't flip, you measure, and as Sabine answered you, the other particle doesn't flip either.
@@SabineHossenfelder Thanks!
11:15 - 11:22
@@TheDanEdwards You are flipping something. Without the flip both particles, though random, are measured to always be in opposite spin states. With the flip, they're always in the same spin state, though which one is random.
I would love to see you do a video on how entanglement works in quantum computing.
Yes! Damn
Thank you for your videos. The CHSH explanation showing QM probability 0.85 versus classical max of 0.75 is more straightforward than other Bell inequality explanations, but I wish someone would do an interference simulation (phase shift) showing why pi/4 is the best angle for measurement.
I really hope you make a video about the many-worlds interetation. I was about to take issue with something you said, but I am glad you at least mentionned it.
For those wondering: the many-worlds interpretation gives an explanation of quantum mechanics which is both local and deterministic.
She didn’t assume non-determinism, just non-locality or measurement dependence.
I am honestly unsure about what she mean by that, and I am wondering if MWI violate measurement independence, or another assumption she used (or the theorem used).
This is unfortunate that she didn’t explain.
@@denisbaudouin5979 To the best of my knowledge, it does not violate measurement independence, because in the MWI the wave function never collapses. What we interpret as the collapse of the wave function is us interacting with the environment and experiencing a single branch of the many existing ones. In a sense, the wave function does not collapse, we get projected into a slice of the wave function (or depending on what we mean by "we". We could also say that difference instances of us are projected into each branch).
This explanation is local because the process of branching only needs to happen as fast as particles can interact, that is at no more than the speed of light.
It is deterministic because all possible outcomes always happen, there is no random process choosing one in particular.
In fact, I remember reading a thesis [1] which proves that there exist local-realist explanations to quantum physics. You don't even need to agree with MWI in particular. The fact that there exist local-realist (and even deterministic) explanations to quantum physics should make us discard non-deterministic, non-local theories as bad explanations.
[1] Raymond-Robichaud, Paul. PhD Thesis. L'équivalence entre le local-réalisme et le principe de non-signalement
Wouldn't many-worlds kinda have this global hidden variable that says which part of the wave function we're observing?
I guess such variable would just be an artifact of assigning some object the role of an observer. If you're gonna model the wave function itself (and not just "what we will see"), then you don't have to keep track of that and everything is back to being local (or just correlated).
seems
@@AGoodGuyOnTheInternet Yes, but I am unsure it means measurement independence isn’t violated, because what you will get depend of the branch where you do your measurement (but I am unsure).
Anyways, if it doesn’t violate measurement independence, it had to violate another assumption of the theorem, and it can’t be nondeterminism (because it isn’t one of the assumption).
@@AGoodGuyOnTheInternet Your reply got shadowhammered by YT somehow. Probably because of the link (these typically get straight-up removed).
When I'm logged in, I can only see your comment ("@denisbaudouin5979 To the best of"…) after I sort the comments by 'newest'. Otherwise I see four replies instead of five.
_Eventually, the goal of developing such a model is to remove the instantaneous measurement update, and hence make it easier to combine quantum mechanics with general relativity._
This sounds kind of similar to Penrose's idea of gravitization of quantum mechanics, where, as it seems to me, the main claim is that the main problem with combining GR with QM is incompleteness of QM. It would be great to hear from you about the approaches of combining GR and QM, and obviously about their problems.
The ONLY problem with combining qm and gr is that no one has the slightest clue as to how gravity can be quantised, nor how it could be that a graviton fits the standard model.
@@aaronperelmuter8433 well Penrose's idea is that we don't really need to quantize gravity, quite the opposite he solves the measurement problem via gravitational interaction between particles. I am not an expert, so probably I wouldn't be able to answer questions regarding this topic. But you can, at least watch some podcasts with him where he tells about his model, it is called an objective collapse model.
I tried searching for Bell's theorem on your channel, but it appears it does not have a video exclusively about Bell's theorem. It would be every enlightening if you can do a video on it.
Isn't THIS video entirely about Bell's Theorem?
Veritasium has an excellent video about it.
Hey Sabine
Thank you:
- That's really good work and insight. I didn't know there were 2 types of non-locality and it helps me understand the concept better. With terms like "Einsteins Spuk (action at a distance)" I was probably misled by all the press releases, thanks. Is it possible that even the quantum researchers who won the Nobel Prize in 2022 did not have this distinction in mind?
Suggestion for a new video:
- The film "Everything Everywhere All at Once" refers to different physical theories and principles which if I remember correctly, are also discussed in your book "Existential Physics".
I think this could lead to a very interesting video if you can show the differences between the film and your book and describe why this is so.
Never ever tired or bored by your explaining, Sabine. Fascinating, even if only about 1% makes it into my (math) challenged brain!
A less mysterious universe is a more pedestrian one.
Ah well, walking is good exercise.
Thanks for this, it was a good overview. I think it brings together topics previously covered.
While superdeterminism is definitely an interesting idea that should be thoroughly researched, I think it's still a lot more weird than non-local QM. Think about it: to determine that λ=5 the photon either has to somehow "know" what experiment the scientist decided to do (which while technically possible would make our universe *a lot* more logically connected than we usually think), or it has to pass through the whole experiment, and then retroactively decide that λ=5 (i.e. send information to itself back in time that determines which path it would take, which is also technically possible, since all current physical laws are time-reversible, but still really-really weird)
Its actually simpler than that, Sabine has made a video about it. It has to do with the fact that the act of measurement disturbs the photon and changes it. Something that has to do with quantum decoherence if I remember correctly...
Why use anthropomorphic language? The photon needn’t ‘know’ which measurement was made, anymore than a ball needs to ‘know’ how it was thrown after the fact. The difference here is that while the phase of the electromagnetic wave might very well be correlated with the environment and measurement operation, its specific value is considered “unphysical” in QM, as only the relative phase between the system and surroundings can be measured from a given basis.
@@otinane89 Yup, watched that video, it doesn't work like that. The problem is not with the photon that is measured "first", but with the entangled photon, that either has to be disturbed non-locally (classic QM), or that entangled photon already had the information about the measurement that researcher would make on the other end (superdeterminism). Both are pretty weird
@@anywallsocket Except that under superdeterminism photon's state is correlated with the measurement that scientist makes *in the future*, and that's the problem. So either photon literally analyzed (yes, in an antropomorphic way) scientist's brain and predicted what they'd do in the future (pretty wild, yes, technically possible, but very-very weird if that were the case), or it received a "message" from the future when it was actually measured.
Also, sorry, but what does the phase of the wave have to do with this? Deterministic wave phase also counts as a hidden variable, and is ruled out by Bell's theorem, so the only ways out are classic non-local QM and superdeterminism with retrocausality
@@silentobserver3433 the phase, as I said, is meaningless alone, and thus is a non-local ‘hidden variable’ (property of the system-environment relation), and therefore not limited by Bell’s no-go theorem.
Also yes superdeterminism implies time symmetry, and thus a kind of timelessness, so backwards and forwards action cannot be distinguished. So whether the ball knows how it’s been thrown or knows how it’ll be caught is the same thing. However this is naive as it cannot explain our obvious experiential sense of time asymmetry of ‘flow’.
Thank you for this awesome explanation! After watching a few videos on this subject I have to say this one was the clearest to me, which might be saying something considering my limited background in physics. It always seemed to me that 'entanglement' wasn't really spooky action at a distance and that the only thing truly spooky was local ... between our ears
I love that for Dr. Hossenfelder, a spacetime diagram is just "a little drawing". Such a fun scientist and scientific communicator!
This is the best most down to earth explanation i have ever heard of spooky action at a distance.
I always eagerly anticipate to watch your videos while enjoying my morning coffee. All is right in the world 🌎 👍😎
You can't affect far away states locally, even in quantum mechanics. I have no idea why she says quantum mechanics is nonlocal. I don't have a PhD in physics, but I studied physics. There was never a reason for nonlocality.
There is an error at 15:34:
One wave function represents A = +1 and B = -1 and the other A = -1 and B = +1 (due to conservation laws). The wave function as a whole moves to A and B. But she has split the wave function into two parts, one moving to A and one to B. That's wrong! Every type of particle has one wave function. Often that doesn't matter, except when it does matter, as we've seen here.
And yes, some parts of the wave function can no longer communicate with each other, but it's still necessary to treat them as one wave function to obey conservation laws.
I think you *might* be missing the point on that. The entire point is "if they are still one wave function", the idea is how can one wave function exist over non-local space. If it's simply nature keeping track of this single wave function "behind the scenes" then that in effect describes the hidden variable idea. But if it's not, then the wave function itself becomes non-local, so thus QM is also non local.
@@aggies11 You got it 100% wrong. There are NO wave functions in nature at all. A wave function is an abstract human construct that makes statements about a hypothetical infinite repetition of the same experiment. Such an infinite repetition does not exist. Technically one can not even repeat the exact same experiment twice. One can only repeat a similar experiment a finite number of times. We can construct histograms from the outcomes of those repetitions and then we can give you a predictive formula that estimates the statistics in those histograms. Nothing in this procedure suggests that nature calculates that formula at all. Since the wave function is therefor not an actual physical phenomenon it can not be local or non-local to begin with. The correct term to use here is "non-separable" and it refers to states like an entangled spin state. Separability is a purely mathematical property that lives in Hilbert space.
Explained so incisively and with a great sense of humor. I watched this video seeking inspiration for how to explain these phenomena to others, and this was perfect. Thanks, Sabine!
OK. If it was so clear to you, please give a definition of "measurement independence".
@@carlhitchon1009 Well, I would say a somewhat technical definition would be that kinematical degrees of freedom of a system constrained by symmetries that do not depend on measurement like Lorentz invariance/covariance are a good example of quantities that are measurement independent. For example, the proper length of a massive particle traced in static Minkowski space, its invariant square contracted momentum, etc. These quantities should share the quality that the values do not depend on one's choice of frame of reference or how one attempts to go about measuring the quantity. A counterexample of a quantity that is not measurement independent is an object's velocity. Or the relativity of simultaneity phenomenon. Also, dynamical degrees of freedom (independent characteristic properties of a system, such as the components of the electromagnetic vector potential after choice of a gauge) can depend on one's choice of point of view (choice of gauge etc.) but are still generally ingredients of measurement-independent quantities (contraction of the field strength tensor etc.) A good way to identify measurement-independent quantities would be to take note of the continuous parameter transformation properties of the Lagrangian that symmetrically leave the equations of motion of the degrees of freedom invariant, which correspond to conserved quantities via Noether's Theorem. For example, the charge of an electron integrated over all of space is a measurement independent quantity.
If I were to try to explain to my grandmother (hypothetically, RIP) what a measurement independent quantity is, I would say that it is like the string of Bingo draws announced by the judge, but a measurement-dependent quantity would be whether this string corresponded to a Bingo on their card - for someone this will be the case but for all others it won't be. (Analogy to the Target Rest Frame - only one observer claims the object of interest is not translating through space.)
Sabine is totally wrong about the existence of measurement-dependent hidden variable theories; in fact, we can always conceive of new kinds of experiments, which implies that a new measurement-dependent hidden variable theory would be necessary for every new experiment, precisely because the hidden variable must depend on the kind of measurement we do. Therefore, such a theory would have no predictive value, but would only be an "ad hoc" justification of already known empirical results. Such a theory would therefore not be falsifiable, and consequently it would not be a scientific theory in any way. In practice, stating that reality can only be described through a measurement dependant hidden variable throry is equivalent to stating that the existence of a scientific theory capable of predicting new phenomena is impossible. This contrasts with the predictive ability of quantum physics, systematically confirmed by countless experiments.
First, she reported, she did not make a statement pros and cons. Second, in my opinion, quantum physics has given up, solving the measurement problem, by the postulate of non-locality as a fact. Every fresh appproach or speculation is worth to be taken seriously
@@Thomas-gk42 You simply ignored my arguments and my arguments prove you wrong. Measurement-dependent hidden variable theories are not falsiable and therefore they are not scietific theories whatsoever; this is why they are not to be taken seriously. At minute 19 of her video, Sabine gives an example of how a measurement-dependent hidden variable theory might adddress the problem of interference. Essentially, you just postulate that there is something we don't know about (a hidden variable) that makes things happen the way we observe them happening. This is not scientific at all and is equivalent to say "we just don't" know". Conversely, quantum mechanics has strong predictive power and has provided many predictions that have been systematically confirmed.
@@marcobiagini1878 Well, I don't see the predictive power, you have a wave function and a 'mysterious' measurement, that isn't a physical process, although you deal with physical objects like measurement instruments. They are not part of quantum physics, but you need them, to describe reality. That shows, that it's an incomplete theory.
You say, hidden variables are untestable and therefore unscientific, but I know, that some brave scientists like Sabine made suggestions to proof it wrong or right. Why weren't these things done? Sounds like scientific inquisition for me.
@@marcobiagini1878 You can't argue philosophically or mathematically with people who think Einstein can't be wrong. They are trapped in a dogma.🙃
@@marcobiagini1878 You talk like you don't know what science is even about.
Imagine one day we get something wrong and stop trying to look at the right direction...
Things can get very complex in the future and if we totally ignore things we may lose track of where we failed.
A real scientist would never believe something 100%, I understand some things may have a higher probability of being right, but just that.
I’m so glad I’ve discovered your channel! You are so engaging and insightful. I love your style. I can’t wait to obsessively watch all of your videos in detail (skip back 20seconds after having my own thoughts and getting distracted and didn’t want to miss a word). 👩🏽🎓👩🏽💻🫶🏽🤘🏽
Thanks
"I'm not going to explain Bell's Theorem, because you've already watched twenty videos about it, and it didn't help." I feel seen. ❤
The explanation of entanglement using closed envelopes is easy to understand, misleading, and wrong.
We consider twin photon pairs. If P1 goes through a 0° polarizer, P2 also goes through a 0° polarizer (perpendicular position).
Now, we assume that the photons, when they are created, are aware of their behavior at certain polarizer positions. So, the photons know how to react at certain polarizer positions. (transmission or absorption)
Any given photon then has a certain probability of passing through a polarizer at 0° and 30°:
W(T(0°), T(30°))
Now, we extend the term by another condition: Response at polarizer = 60°. So that the probability does not change, we consider both possibilities:
W(T(0°), T(30°)) = W(T(0°), T(30°), T(60°) ) + W(T(0°), T(30°), A(60°) )
Now, we omit one restricting possibility on the right side:
W(T(0°), T(30°))
It's interesting that in the physics community so many people just brush these issues under the rug. Of course it can't go unnoticed after last year's Nobel Prize, but you do a great job by reminding us about it and explaining it to the general public (although as you stated at the end, you need to be familiar with some basic concepts of quantum mechanics in order to understand it.)
What issues do they push under the rug? Can you give an example of when the community does so?
@@alterego3734 There really are no realistic issues, this claim of super-determinism/measurement independence is on the order of "But if every particle contains a supercomputer with enough memory to store all of future space-time, and calculate its future interactions with every other particle before the interactions occur, then they could give the observed measurements in our labs! Much more likely than RNG in the natural world, right?". I mean, sure, that's a possibility (?), but maybe it's fair to discard it as absurd? (Which is what Sabine refers to when claiming that the physics community discards the idea).
If there's an experiment that can verify that measurement independence can't be trusted, I'd receive the greatest mind blow of all time and it would be amazing to be proven wrong along with most of physics. It sounds hard (impossible?) though to construct a test to check if the particles are conspiring against us when we try to measure them, by measuring them...
No its not that. I think its more that for most physicists working with quantum mechanics they don't actually care what it means in terms of describing reality. Its irrelevant to them, so isn't a topic for discussion. All the matters is what the maths says, what that means for reality can be left to philosophers.
@@chalichaligha3234 physics is stalling, yes, but I dont know if I fully agree this is the reason why physics has stalled. Quantum mechanics has lead to very real practical applications. It doesn't matter whether that means we know in a multiverse or not. Theres no way of finding out anyway, which is why its a question for philosophy. Physics is not philosophy.
I think I'd like some info on how it's possible to change a particle's state without measuring it - the only part of the video I didn't really get. It's probably super easy once you explain it, but that's exactly why I'd like a video on it~
Well particle states were around a long time before humans came along to measure them : )
For example, a magnetic field can change the axis of the spin, without forcing a state collapse like a measurement would
if I'm not mistaken you can affect a particle in a random way, like going through a perpendicular magnetic field that will spin the particle 90 degrees in a random direction. you don't know what direction the particle is spinning, but you know you changed it because it has to align with the magnetic field either spin up or down.
@@SergioBallestrero Thank you! The other reply from ArtisanTony didn't really convince me because I remembered Sabine talking about how it's a misconception that only human-made detectors can "measure" things, (I think that was in her Superdeterminism video) but this seems understandable.
@@SergioBallestrero That's kind of what I meant :)
Excellent Sabine. It’s indeed curious that physicists keep ignoring this second interpretation. I am not a physicist, my research is on AI which focuses very strongly on building models. It seems to me physicists keep thinking that the models of physics are really the physics and not a model. It seems to me that they confound map with the territory, and they keep stating that physics are uncertain in itself instead of the model having uncertainties.
Physics is (not are) uncertain, some guy called Heisenberg has a principle name after him. It’s called the uncertainty principle, you may have heard of it before? It refers to physical reality, not models of reality.
@@aaronperelmuter8433 The Heisenberg Uncertainty Principle talks about the commutator of two operators. It's a model whether you ascribe ontological status to these operators.
Damn, Sabine forcing me back to reality whether I like it or not. Thank you
The distance between two points is change in possibility. You need to disconnect from A to emerge at B. Its why A divided by zero equals NOT A (a set unrelated to A except at superposition) you need to stop interacting with A to be able to interact with B..
Unbelievable how much one can learn from a 20 min video like this
The last thing I expected in a Sabine video was a Mortal Kombat 1 reference
If you're referring to Toasty, that was local with Mortal Kombat 2.
@@AdamBlue oh no, my gamer cred! It's gone!
@@dingo4530 haha don't worry, I don't care about your gamer cred. I don't even know you. But like with quantum entanglement, misinformation needs to be corrected. 😉