I can't read the math, but seeing it still helps me grasp what is going on. I feel you are part of a new wave of science communicators that brings this aspect to audiences in a way no other popular presenters have done.
i don’t understand it at all but im glad there are people who basically prove things with math, somehow. like who knew math could model something so complex like the cosmos.
You could read the math here. It really isn't that hard. Just a little effort. It is using Dirac's notations which is just a fancy shorthand for linear algebra. Super cheap book called "A Student's Guide to the Schrödinger Equation" ISBN-13: 978-1108819787 or ISBN-10: 1108819788 which breaks it down pretty quickly. If you don't know what Linear Algebra is... it is not hard at all like maybe calculus is for some people. Linear Algebra does a lot of Matrix operations. It mostly might just "seem hard" because maybe you've never seen it before... but once you become familiar... it becomes like everything else. Who knows, you might like the taste of it and pick up a physics addiction. BTW Paul Dirac was a ridiculously powerful mathematician in his own right. I would argue that he potentially was the greatest physicist of the last century. With Einstein coming in second place.
I don’t see the point of so called science communicators. If you cannot understand the maths then you can’t do anything with this, in the best case scenario knowing these theories without their formulaic with construction is useless trivia and in the worst case scenario causes people to think wrongly and draw bad conclusions which is why we have so many Deepak Chopra types running around.
@@peterader3073 Do you not see a point for economists to communicate economic conditions and lawyers to communicate legalities, too? A lot of people want to stay in touch with modern scientific knowledge without being a scientist who fully understands it.
"the details shall be left as an exercise for the reader" is a frustrating cop-out that assumes the reader (or viewer, in this case) even knows wtf to even do to complete the so-called exercise. Nick, I am absolutely grateful to you for NOT leaving that exercise to us, your viewers, and not only working it out yourself, but showing us your work and setting an example.
I mean, keeping in mind the intended audience is key. There's a big difference between an advanced textbook on quantum theory that assumes the reader has sufficient mathematical background to work out such derivations, and a UA-cam video aimed at a general audience. If the video/book/whatever is aimed at a general audience, as Nick's videos are, it would make little sense to say something like that. But if the work is aimed specifically at advanced students of quantum theory it wouldn't be so unreasonable to assume the reader is capable of doing such derivations. That said, personally, I don't like the practice of saying "the details will be left as an exercise for the reader" because it can come off as kind of lazy on the author's part -- it'd be better to just make it one of the questions at the end of the chapter.
I have all the respect in the world for a physicist whose style is the opposite of the style of those who say "the details shall be left as an exercise for the reader."
That line near the end was the most clear and understandable thing I've yet heard from this channel. "We need to relax our expectations." Wisdom for life in general.
One of the most Empathic Videos i ever saw just came out: "Why do I Care?' by 'Belief It Or Not'. Together with the GOP-Videos of 'Some More News', its quite amazing and best coverage of the Attack on Woman-Rights and other things, i know. For those who wanna be updated and those that have Empathy (a combinttion that will make you wanna know about the current Abortion-Right Chaos), this is for you.
@@DavidHeizer An "observation " can be done by anything. A random particle interacting with the electron would force it into a state, thus, collapsing the wave function, and "making it happen"
Funny thing about a lot of these QM explanations is that even though QM itself being unintuitive is true, the really unintuitive part to me is how these experiments are physically performed. From the usual diagrams it's often pretty hard to imagine how these detectors work, or how they manage to get one entangled particle into space without, well, doing the particle equivalent of dropping an egg you were carrying in a spoon with your mouth. :P
If you read the details of the experiments performed and how the machines are built you can get an idea as to how they work and how they are used to perform a test. They're tools that are expected to give precise values about a specific aspect of reality. I suppose you can say that they're very advanced tools that not many people can think of and even the people who thought of them had to spend a lot of time thinking about them, testing them, and getting them to perform as intended.
I think the record for entangled particle separation is several hundred kilometres? They used fibre optics and phased photons or something? If you think about it some quantum particles are huge, hundreds of kilometres across - I still can't visulize how radio wave photons show quantum effects (but they do).
@@jitteryjet7525 I think we're misunderstanding "size" as it refers to waves and their interaction with things. For example, audible sound waves can be up to 17m. How does the human ear detect that without rupturing? Radio waves can be kilometers in size, yet are produced and detected by pieces of metal mere cm long. I think the answer is that the detector (or interacting object) simply takes a portion of the energy from the wave, and the rest continues on. That is, it takes from the *amplitude* regardless of the wavelength, and all it needs to be is in the path of some photons (or particles of air). (Amplitude is a silly concept for photons, though, as all the energy is described by the wavelength, but then how does Amplitude Modulation work? I think what you could say is that some photons are absorbed by the detector, transferring the energy to the wire which then replicates the absorbed waveform, which is comprised of many photons of slightly different wavelengths, into an electrical signal). It's also important to remember that photons (like all quantum objects) exhibit wave-particle duality. They are a spread-out wave when it's convenient, and they are a pinpoint particle when it's convenient. And sometimes they are both. Also, something I think people forget: the wavelength is literally that. The wave *length*. As in, the distance from one peak to the next. Along the direction of travel. Is any of this making sense? I'm confusing myself here.
@@RaunienTheFirst I am not misunderstanding size. My point is the exact position of a particle can be somewhat muddy eg if you don't know the exact position of two quantum particles, how can you say they are in separate locations? They might still overlap in space (somehow).
That frustrates me , because I have never seen even a basic explanation of how these detectors work , even though they play such a important role . The explanation of how the detector works in this video is far too simple . I kinda just assume they are using magnets , since spin is just a magnetic particle . If they are using magnets then why wasn't it considered as a potential hidden variable ?
You make a lot of great videos but this one was exceptionally good. I think this was the first time I've ever seen anyone actually points out how you get an entangled pair of particles. Thank you!
@@ScienceAsylum My money is on wormholes connecting the particles, also known as ER = EPR. In Einstein and Rosen paper about Einstein-Rosen bridges, they concluded that wormholes would instantaneously disappear the moment they are created. Their conclusion is correct, but for static wormholes. The problem is that Einstein had his mind locked in a static Universe, because that was the data on the time, and he did not think of moving space, which ultimately caused his "greatest blunder". In order for a static wormhole to be stable, it requires magic, he correctly concluded. But if the wormhole is rotating, it has been proven that it remains stable and does not need any sort of appeal to magic to keep the throat open. I strongly believe that entangled particles share information through rotating wormholes.
@@fahrenheit2101 No, it's just the name of the experiment he was describing. The important thing is the principles. Names are just names. However, you can certainly use that name to search "Bell Inequalities", and now have an excellent primer on the topic. John Bell had amazing contribution to physics, but most people probably haven't heard of him.
@Lady_Sugar Principles in science is equivalent to Axioms in mathematics. This are statements that are accepted to be true because we have not found counter examples. Laws are derive from mathematical models of our universe and they get broken in cases where the mathematical models break down. For example dark energy violates the law of conservation of energy because conservation of energy is derive from a mathematical model that has time translation symmetry which is only true locally but is not true in the cosmic scale.
This is a very well written episode. It may not seem that way to the non-expert ears, but the words are chosen so correctly and so good to reflect a correct and pure and consistent understanding of QM and to connect the well- established mathematics of QM to its philosophy and the connection between the two (which was not appreciated for a very long time in the history of QM, until John Bell's great contribution) in a clear, intuitive yet precise way. Well done Mr. Lucid. Also those looking for further material, can search for Prof. Leonard Susskind's lectures on what he calls "ER=EPR": the hypothetical connection between wormholes (ER bridges) and entanglement (EPR)
Once more Edwin Hubble popped into my mind: "Equipped with his five senses, man explores the universe around him and calls the adventure Science." Thanks a lot for another of your really fantastic videos! I like them all.
Three things. 1)Please do a video on superdeterminism 2) Statistical independence is something that Bell assumed, but such assumption can be challenged in quantum world 3) ER=EPR
There is a possibility that doesn't violate locality: no matter how far apart the measurements are, the two observers still need to meet and compare notes locally. It could be that at the moment of measurement, the observers themselves become entangled with that superposition too, and then become entangled with each other when they share information. They don't experience the superposition (i.e. their memory remains consistent from the moment of measurement until they confer with the other observer) because their memories are also part of that superposition: the superposition is the set of all states that are self-consistent over time and space, and any verification of what state it is in also entangles the verifier, making any possible perception of the state also self-consistent over time and space. This is how "Many Worlds" really works, and why it's a misnomer. It's not that there are actually several different universes that somehow physically split apart and duplicate matter somehow. There is only one universe, but that universe is a constant superposition of all possible self-consistent states, re-entangling with itself over and over again, and our experience of the universe is just one of these self-consistent states within the broader superposition. (a better name than "many worlds" imo is "Eternalism", which is a concept from the video game Warframe, named after the philosophical theory of time. Basically, Eternalism in Warframe is the idea that the past and future exist as a solid and unchanging block of all possible states of the universe, and that our subjective experience is like a single path winding through that block, with each "measurement" or "choice" changing the direction of our subjective world-line but not the solid block of possibility itself. In other words, Schrodinger's Cat IS both alive and dead, but either way Schodinger will only remember it being one of those, and so will you when you ask him which it was, because you and Schrodinger and the cat are all entangled with the state of the quantum particle.)
Wow! I've been reading on EPR Paradox for a long time but this is one of the best explanation for the resolution of it. So hard to get your head around all this without having a solid understanding of the math behind it. Thanks, Science Asylum for making it accessible for us, mere mortals.
I can understand dealing with a pair of particles in the lab, but here and on another world, how do you do that??? There's no directory for entanglement...
One of the most Empathic Videos i ever saw just came out: "Why do I Care?' by 'Belief It Or Not'. Together with the GOP-Videos of 'Some More News', its quite amazing and best coverage of the Attack on Woman-Rights and other things, i know. For those who wanna be updated and those that have Empathy (a combinttion that will make you wanna know about the current Abortion-Right Chaos), this is for you.
This is the clearest explanation i've heard - plus it gives an example of how entanglement is generated....most explanations start off with they just are.
The conclusion about "communicating faster than light" we get only in certain interpretations, but in MWI we can still save locality, as Sean Carroll nicely explains in his book. In each "world" changes in state propagate not faster than light, then during the measurement you just learn in which world you're in. So beautiful. I guess it's a case of non-local hidden variables which aren't ruled out by Bell's experiments.
Yeah, many worlds, ties everything up very elegantly. No more troublesome non-realism or non-locality, no more hackish contradictory Born rule, no more measurement problem. But, like, it sounds stoned, so let's just keep all of those contradictions. -Copenhagen
I think you forgot to mention that Bell experiment doesn't invalidate hidden variables, only LOCAL hidden variables. A non local hidden variable model is still possible
Exactly. It’s likely the entangled state is one state in 4D appearing as two particles in a 3D slice - so our classical sense of ‘locality’ needs an upgrade.
@@ScienceAsylum Yeah I recognized the De Broglie wave pilot. But again yeah I think the conclusion of your video is a bit misleading because it makes it seems like hidden variables are definitely a goner whereas it is not the case
@@ScienceAsylum some have already asked about this, but I will too: what is your response to the Sabine Hossenfelder's video/thesis about superdeterminism? In it, she said that Bell's theorem has three assumptions about theory in question: 1. It is deterministic (so hidden variables exists) 2. It is local (so it fits with GR and so on) 3. The Statical Independence is true She said, that most physists had BELIEVED in this third assumption, without real evidence for it, and they managed to forgot it's even in there. However, she says, if one discards Stastical Independence (like superdeterminism does), then the Bell's theorem no longer holds and one can get local AND deterministic version of quantum mechanics just fine. I have to say, she's got the point about the irrational belief in the Statistical Independence, as you for example did not even mentioned it, so you've created the impression in the viewers that local and deterministic theory is just impossible, period.
I always think of “hidden variables “ not just as the variable being hidden, but the whole logic behind the variable being weird and unintuitive, not just an unknown number. It is predetermined to be up and down, but not the value itself is predetermined, but the whole equation, along with its logic, which is weirder than QM itself.
I only understand a small portion of the stuff you talk about on this channel but it fascinates me to no end!!! Thank you for taking the time to explain these things to regular people! Haha
Have you seen sabine hossenfelder's videos on quantum entanglement and hidden variables? she seems to take quite a stance against the version you propose here.
My guy you consistently find amazing ways to explain these ideas. The way you summed up Bell’s basic premise really helped me understand how someone could come up with the idea, but I’m glad I don’t have to do the math to work it out.
I was a bit confused because 7:12 says there are only 6 possible outcomes. But it looks like binary numbers to me, having 3 bits would give you 8 possible outcomes. You could add {+a, +b, +c} {-a, -b, -c} Does that mean that spin has to be different on at least one axis when measuring on 3 axis? If so, why?
{+a, +b, +c} and {-a, -b, -c} are options in general, but not in my specific example because of the way I oriented the detectors. It's impossible for all the signs to be the same when they're all 120 degrees apart.
I really think that this channel sets the trend for science communication on the internet. I hope that more and more of these channels gain popularity and prevail over the silly psuedoscience that seems to be so popular right now. This channel shows people how science is way more fascinating than coming up with some magic story, just to fulfil the need to feel special. As shown in this very upload, the universe is special and so are you down to your very quarks! I do worry that people are hesitant to understand science as if 1 concept goes against their presuppositions, they revert to science denial and to me, the most dangerous cultism facing our species.
I don't think this is likely. Single particles that are not entangled also display the same sort of weirdness in the double-slit experiment, and in that scenario you can fire them one particle at a time launched at random times and still get interference - how would the higher dimensional space or the worhhole know where to go to be "close to" the previous or next particle in time. It doesn't even need to be in the same space, you could build 5000 machines and fire only one particle through each before disassembling them and still get the interference pattern when you merge the results. It just IS probabilistic.
Maybe the most unambiguous explanation currently on UA-cam of QE and the Bell inequality experiment and how it resolves the EPR paradox. All that in less than 11 minutes. Bravo!
I'm so glad to hear Nick say it out loud. "Entangled particles can interact faster than light." Can anybody answer this question: Is every superpositioned particle (with or without entangled fellows) oblivious to locality before it's "measured" into 3d?
Congratulations, you're the first to show us which maths were behind the whole thing! I've looking for this math quite a long in the whole internet, and I've even found a page with mistakes in the math! Thanks a lot!! As you say, Quantum is not magic, but rules (and calculations) ...
Thank you for the great explanation! It leaves me with a few questions - for the three angles, is there a minimum degrees apart? Instead of 120,120,120, what if they were a billionth of a degree apart, so basically 360,0,0. Would we still see 50-50? If so, can we really tell if two measuring devices very far apart are within a billionth of a degrees off axis? If not, then wouldn't all measurements be 50-50? The basis of my question - two measuring devices can not be exactly oriented the same, so wouldn't all of them return 50-50, even if we think they are aligned along one ais?
Too often in explanations from various science communicators I don't hear about higher dimensions being part of the explanation for quantum weirdness we observe. So THANK YOU, Nick, for giving that credence and a nice quick primer.
The first time I heard about entangled particles was in high school, and Instantly thought, the particles were just stretching space in between one another. I thought to myself that if that was the case, then we could one day potentially measure how far space could be stretched on that level and at some point maybe even notice a delay in the particles. Since we haven't actually measure them in the vast distances of space.
I came to the conclusion that entangled particles are actually one object. Think of it like how your three-dimensional hand can touch a two-dimensional sheet of paper in two or more places without directly touching any of the two-dimensional space in between. I'm pretty sure the idea is congruent with quantum theory. I just have no idea how to measure the topology of an object with 4 or more physical dimensions.
As someone who has a background in Physics, I always went along with the accepted point that the randomness within a quantum entangled system prevents FTL communications. I recently read a book 'Cracking the Cosmic Code' which actually shows that the randomness is not a restriction at all. It now opens up the distinct possibilities of FTL communications.
Thank you for your channel. I conduct outside the box experiments on my page here and anytime there is something I need clarity on I come to your site here and I always find an answer that is laid out in such a way that anyone can understand the workings of it.
Mr. Lucid, What is your stance on statistical independence when discussing Bell's Theorem? For example, the arguments brought up by Sabine in her super-determinism video. Thanks for the content
Sorry to intrude but superdeterminism implies ‘suppose the two detector angles are chosen at random’ no longer holds, and so 55% would not be the expected outcome. As for what it would instead be, I’m not sure.
@@anywallsocket yeah, but that's the point, ins't it? That it's an assumption of the experiment which arguably might not hold, possibly invalidating it's standard interpretations?
@@user-sl6gn1ss8p well at the end of the day we can make our decisions based off of local noise (highly random), so previous correlations break down and superdeterminism starts to suggest that everything is always correlated, at least somewhat, but that starts to sound unfalsifiable and therefore unscientific.
6:43 Very nice explanation of the Bell Test! 7:21 Especially the notations of the possible outcomes! Very elegant, and probably the best I've seen in the last couple of years! I see clearly now why Hidden Variables are rejected, because they would require the test to yield 55.6% opposite outcomes, instead of the 50% observed!
It depends what you define as "interaction", but I personally would be careful calling it "faster than light interaction". After all you can't transfer any information faster than light with this. If you have two entangled particles A and B, then you can do whatever you want with A, you will not be able to detect that "something" happened to A by just observing B.
Indeed QM does not describe the occurrence as an "interaction", nor causation. The formalism is "talking about" the "effect" of conditionalization on correlated systems (in the traditional QM parlance that is the collapse of entangled states). Note, as Einstein also pointed out, that we can make a similar consideration even without considering correlated (entangled) systems, but just one system, i.e. across alternatives (e.g. when alternatives are across a space-like extension, in respect to relativity, conditionalization over the alternatives has the same behavior as conditionalization of space-like separated correlated systems). This is, though, the "normal" behavior of conditionalization in a probabilistic theory, e.g. the relation of conditionalization and relativity in QM and C(lassical)M is the same, be it for correlated systems, or across alternatives of a single system. The issue with QM emerges when we combine this with the indeterminacy of QM (which is in fact a property of quantum logic, as the algebraic structure of quantum probabilities), and it is about what we can accept as a warrant of the results that factually match the prescriptions of QM formalism. It is a novelty of QM respect to CM because the latter, and at its core classical logic, admits the deterministic formulation of the probabilistic theory (we are used to give the deterministic formulation of CM for granted, then eventually "generalize" it with a probabilistic formulation, but epistemically the correct reasoning is the other way around -- knowledge is always limited, we always have limits of resolution). The fact that in CM/CL the theory admits the deterministic formulation is what "trivializes" the probabilities to being purely epistemic, i.e. in the indefinite limit of uncertainty removal, the theory is informationally complete and deterministic, that is, it "trivializes" probabilities in the sense that there is no proper information in the probabilistic layer of the theory since all the information is in the deterministic one. Alternatives and correlations are non-local notions both in CM and QM, while the mechanics, i.e. causation, is local, also, in both theories. The difference is that the probabilistic formulation is informationally trivial in CM, i.e. the information is complete in the deterministic formulation of the mechanics, which brings with it that it is locally-complete for CM. In other words, alternatives and correlations are warranted by the deterministic formulation of the theory, which incidentally is local. This is not the case for QM. Quantum logic has different atomization properties, that exclude the existence of the limit of indefinite removal of uncertainty, which is essentially the indeterminacy property of QM (the limit is not unique, as the limits are the basis, and between basis indeterminacy relations holds). QM does not admit a deterministic formulation of the theory as it stands. Thus, the information encoded in quantum probabilities is not trivial, in particular in respect to alternatives and correlations (entanglement is holistic correlations), which are not local, resulting in the fact that quantum information is not locally-complete. This is what EPR is evidencing to argue that QM is incomplete essentially "because it must be" locally-complete. Is this a correct claim or is it a prejudice stemming from being accustomed to classical physics, and determinism in particular? Does QM propose to us a different way to look at the universe? I agree with the author of this video when he says that we need to relax our expectations. I even consider this an euphemism, I think we need to start thinking that it is QM that sets our expectations, not that we have to understand it by what we expect (on what ground?). If QM is our fundamental physical theory, that is how we should approach it: "understanding QM" then means "understanding by mean of it". In any case, FTL causation is dismissed in the EPR argument. I am not aware of viable proposals based on it. If there are, they are in competition with other approaches. Furthermore, as noted above, QM itself does not employ, or "talk about", FTL causation.
Have you seen Sabine Hossenfelder’s video on super determineism? She says that Bell’s work assumes statistical independence. This is a fine assumption, but it is just an assumption. It seems that no one questions the assumption because people want it to be true and everyone thinks it’s true. That’s understandable but it’s not science. And there is a long history of very bad science based on what people want and what’s popular. Personally, for me super determinism seems a much simpler description of the universe then all the contortions people go through to explain entanglement.
Yah she poked plenty of holes in the common interpretation of bells theorem. But youtubers gonna get more clicks if they claim magical explanations, so much for science...
Maybe Bell's experiment shows that the properties that we formerly labeled as "up spin" or "down spin" were never literally up vs. down. They were inward vs. outward. Under this arrangement, the inherent chirality of the universe is preserved.
Question: in your experiment what is the state of the two particles according to an observer that knows nothing of the outcome of the observation? Are the two particles still in super position according to them? Then if they never interact with the original observers can they measure the spin and see a different outcome? If so, does this mean that the observers have different realities? Then they could come together and share their realities and realize that they are incompatible?
This is a surprisingly good question. Not sure that it can be answered, even in principle. I think it lies at the heart if the Many Worlds theory (of which I am not a fan, although I understand the attractivenes of it, because of this question).
The observer isn't necessarily "conscious", "sentient", or "sapient", if that's what you meant. As far as I understand, any interaction where the particle's state is relevant with outside systems causes the wave function to collapse.
Ya he makes that clear in the video that the observer does not need to be conscious. I was wondering about the relationship between separate observers. Do they need to be connected in some way for the observation by one to affect the observation by another. Kind of wondering if there is an objective reality. You seem to be saying there is for sure but how do you prove that?
Another home run, Nick 🙌 Also at the risk of sounding like a shopping bot - I truly did just buy 4 of those shirts for our family. Gratuitous promotion works!! We're all just big fans. Thank you 🙏
This helps from the previous video when I asked about this exact thing! I am wondering if you could maybe in the future do a video on the "Light polarization paradox". Where if you have 2 lenses at 90 degree angles, it blocks out all light, but if you insert a 3rd lens between them at 45 degrees, light can start passing through again.
That is not a paradox, and can be explained by classical electromagnetics: light is only blocked when its polarization is perpendicular to the filter, when you have 3 lenses, each 45 degrees apart, this never happens.
@@anywallsocket Correct me if I'm wrong, this happens only when all three filters lie on top of each other and act like one filter? If I take 3 polarized filters angle them at 45 deg but put some distance between them?
@@ScienceAsylum awesome! It would be nice if you could talk about the polorizing filter-particle interaction. For particals that pass the filter the filter changes the particle's spin direction. It's possible that you don't need hidden variables to have locality. If both entangled particles pass and both were measured in the same direction then they were probably close to the filter's orientation. If you measured in different directions then only a very small percentage of times you get that both passed. In that case the one that passed while being far from the filter orientation can become closer to random 50% depending on a local partical-filter interaction
I think you mean polarisers rather than lenses? An interesting thought experiment is that you can continue the thought experiment beyond 3 polarisers - keep adding polarisers at just the right angles and you can get smooth, continuous rotation of the light polarisation with *zero* loss. Bonus fact, such devices are called Faraday isolators or polarisation rotators (depending whether the device is non-reciprocal/magnetic or not). Both are used routinely in optics labs.
The funny thing is that among the explanations you floated towards the end, I’d order them from least to most crazy-sounding as follows: “pilot waves (de Broglie Bohm), worm hole (ER=EPR), many worlds (Everett). 1. But to actually resolving confusions about entanglement, Everett probably does the best job. 2. The pilot waves doesn’t handle relativity and quantum field theory too well as far as I can tell, which if true is quite a bad problem. The basic idea is applicable to other wave problems, completely unrelated to quantum mechanics though. 3. There is some teeth to the wormhole idea as a thought experiment to probe quantum gravity. So it probably won’t come as a surprise that this idea hits on some pretty advanced physics which this kind of video can’t give nearly enough tools for a proper discussion. My comments won’t be terribly illuminating either. I will say this; To the extent that there is a connection between wormholes and entanglement, it’s not obvious that wormholes should be though of as more ‘fundamental’ object. It might instead be that entanglement is the more fundamental notion and that some special quantum states with lots of entanglement configured in a particular way is how spacetimes and wormholes are described quantum mechanically. Another possibility is that it’s better to think of it in terms of a correspondence between two equally good ways of describing the same physics. Even if wormholes isn’t the explanation of entanglement, I’d bet this line of reasoning is more likely to be important for fundamental physicists than the pilot wave idea is.
In the Many Worlds Interpretation, the branch occurs at the moment that the wave function collapses, right? So to clarify... if we're separated by a great distance, you have one particle in an entangled pair and I have the other, we're still in the same reality. As soon as you measure your particle, we now have two worlds. In one of the worlds, you have an up particle, and I have a down particle. In the other world, you have a down particle and I have an up particle. But reality doesn't branch until you make the measurement, right?
@@cykeok3525 No, not really. Many worlds doesn’t have collapse. That’s one of the main features. Time evolution only ever uses the Schrödinger equation and nothing else. Locality of interactions is better encoded in QFT, and more details about the specific laws of physics needs to be imposed. If you do that however and then lay out the ideas of MWI branching is local. Its better to think of it as systems becoming entangled with each other. Say two particles are entangled. Then the measurement device by some interaction becomes entangled with the particle close to it and then you becomes entangled with the measurement device and so on. It’s not like the world “splits” all at once. Measurement is a local process and affects nothing far away. At least that’s the idea. More details are needed to make the logic clear this is the extremely rough version of it. The takeaway is MWI is just plain old quantum mechanics without the measurement collapse postulate. In principle, nothing more, nothing less.
Couldn't it be possible that the entangled particles just share the same "seed" orientation determined when they were entangled which then evolves according to some predictable process into the observations? My thought is based on the analogy of a 2fa code in an authenticator app, you share some "key" which is then factored into an equation that turns it into a pseudo random number, but it's a predictable value, so we can use it for authentication, just compute the code once on both ends and compare. No need to transfer data faster than light at all. The only difference between this analogy and entanglement is that rather than resulting in the same value after calculation, it's the negative of that value instead.
If there is a seed, then the outcome of all three orientations is determined for a particle, exactly as shown at 7:20. So, a particle would have a "hidden" positive or negative value for each of the orientations, and in its entangled pair they are all the opposite. If you do the math, statistically you should get different signs 55.6% of the time. Here's a summary: For example, assume the seed of one particle results in: (+a, +b, -c) Then the same seed should result in (-a, -b, +c) for the other particle. Also, note how we choose the orientation to detect randomly with 1/3 probability for each particle individually, so there are 3x3 = 9 possible ways of detecting each with equal probability, 1/9. I will write the detected orientations like this: [a,b] means we detect in orientation a for the first particle and orientation b for the second particle. [a,a]: (+, -) -> DIFF [a,b]: (+, -) -> DIFF [a,c]: (+, +) -> SAME [b,a]: (+, -) -> DIFF [b,b]: (+, -) -> DIFF [b,c]: (+,+) -> SAME [c,a]: (-, -) -> SAME [c,b]: (-, -) -> SAME [c,c]: (-, +) -> DIFF Remember how each of these had equal probability? There are 5 DIFF results but 4 SAME results. So there is a 5/9 chance that we get DIFF but only 4/9 chance we get SAME. If we run the experiment many times on lots of particles, we should see roughly 5/9 = 55.6% DIFFs. But that's not what happens... In reality, if the two particles are detected in the same orientation, e.g. [a,a], the outcome is still DIFF (1 positive and 1 negative), BUT if they are not in the same orientation, they are more likely to be SAME than DIFF, which doesn't make sense at all. If you take a look at the list, when the detections are not in the same orientation, there should be a 50% chance of being SAME or DIFF. It's as if the other particle is trying to copy whatever this one did in the orientation it was detected in, regardless of what the "seed" tells it to say. P.S. If you're wondering what the 50% mentioned in the video refers to, it is the overall probability of seeing SAME and DIFF in reality, including detections in the same orientation. Since all those detections are DIFFs, then the detections in different orientations have to have more SAMEs than DIFFs to get it to 50% overall, which is weird.
Why at 7:20 does he say there are only six possible outcomes instead of eight? If you include (+a,+b,+c) and (-a,-b,-c) then the 50/50 observation when measuring in DIFFERENT directions is exactly what you would expect from classical physics. (To be clear, at 6:52 he says, “Something interesting happens when the two detectors AREN’T measuring in the same direction”, which flows into the 50/50 observation.) What am I missing? Or did I just break quantum mechanics?
@@darylmartin4263 First, he didn't include those because it wouldn't make sense in classical physics for a particle to have the same sign in all 3 directions. Imagine you're moving in an unknown direction, and your movement is measured in 3 specific orientations with 120 degree intervals. How can you possibly be moving positively in all 3 orientations? There should be two positives and one negative or two negatives and one positive. We are actually measuring the spin and not the "movement", but the analogy still holds; it wouldn't make sense for it to have the same sign in all orientations. Second, even if you include that for a total of eight outcomes, you would still see more DIFFs than SAMEs. In fact, for those particles you would only get DIFFs; one particle is always positive and its entangled pair is always negative; so we should measure it to be more than 55.4%. But no, we get 50/50 DIFF and SAME overall. In classical physics, the 50/50 observation when measuring in different orientations is indeed what we expect, but not all detections are in different orientations. Some are in the same orientation, where we expect different signs 100% of the time. Therefore, *overall* we should get more DIFFs than SAMEs. But in quantum physics, and in reality, we get 50/50 *overall* . So, even though we always get a DIFF when measuring in the same orientation, the measurement in different orientations is *not* 50/50. It actually is more likely for them to have the same sign. But how the hell is this possible? And how does quantum physics try to explain it? Well, the only way we can wrap our head around it is this: When you measure one of the entangled particles in a specific orientation, it immediately forces the other to take its *exact* opposite orientation, no matter what it was doing before that. That way, when you measure the second particle in a different orientation, its "forced" orientation is only 30 degrees away from the measured orientation, so it is more likely to give SAME than DIFF. Does that mean measuring one particle affects the other faster than the speed of light? Yes. But isn't that... spooky? Yes it is. It's "spooky action at a distance".
@@adoosth I don't get your statement "How can you possibly be moving positively in all 3 orientations" Why is this impossible? For instance, it's possible to have all positive components of a velocity so
@@lietpi From what I understand, the detector doesn't measure spin in 3d space but a 2d plane of space. Therefore, you cannot have a positive detected for a, b, and c because each only has x and y coordinates.
This is the best explanation of Bells' thought experiment that I've ever seen, and the only one that doesn't even mention "spooky action at a distance". Congratulations!
Nothing spooky going on, the 'interatction' measured in QE is a point in the past. Einstein made a joke in some notes and people have been freaking out about nothing for a while now. Is it cool and interesting? Yes. Is it remotely FTL? No.
2:02 One explanation I really love for this interaction is the one that says a positron is just a time-reversed electron. What that means is that when you see the photon disappear and a electron/positron pair appear, what's actually happening is a time-reversed electron is colliding with the nucleus, it absorbs a photon (or emits one in reverse time), and then it changes direction moving forward in time as the electron we observe. It changes an interaction between three particles, two of which are entangled, to an interaction between two particles with one of them simply reversing its direction through time, no entanglement required.
@@kendrickmcelfish2805 In a sense, yeah. If we restrict the example to an electron/positron pair, you're basically measuring the same particle twice at different points in its lifetime.
"We need to relax our expectations". Totally agree. It's ok by me if I don't have the Absolute Truth served for breakfast with my coffee. And maybe we need to, ontologically speaking, give a bit more weight to role of probability in constructing reality instead of just insisting that only what is actual (whatever that means nowadays) can be real.
Great vid! Would love to see a video on the delayed-choice quantum erasure experiment, as I cannot fully comprehend/understand those results. I think the key to understanding quantum mechanics is avoiding trying to visualize based on particles moving about in our 3D space, and trying to visualize as wave energy blips in a quantum field, where entangled wave energy blips are part of the same entity with instantaneous coordination in their respective quantum fields, and resolve to a particular spin (and as a particle rather than a wave) upon wave function collapse at measurement.
I covered the quantum eraser a couple years ago: ua-cam.com/video/iyN27R7UDnI/v-deo.html My pace was a little faster back then, but it should have what you're looking for.
@@ScienceAsylum Thanks for the great video that you posted. I like that you actually provide a possible solution that in theory could work, rather than just explain it away based on correlations retrieved after the experiment is completed (like some others that you can see on youtube). I do however question whether your proposed solution makes sense. I posted my comment on your other video. Here it is here: Hmm, re your comments at 10:40 that what happens on the screen determines whether the which way path information is erased or saved -- I saw that at a possible explanation somewhere, but in theory, the experiment can be modified to allow a human to randomly allow / disallow the entangled particle to pass through the splitter/detector or bypass the splitter/detector after the other particle hits the screen (e.g., imagine the detector / beam splitter being a light year away from the rest of the experiment). So, if the particle that hits the screen communicates to the entangled particle at that moment, the human could in theory change the outcome by physically moving the splitter (or detectors) into / out of position after the other particle hits the screen. I'm not a physicist like you, so perhaps I'm missing something, but the only solution that seems to work in my head is that there is no wave function collapse at the screen when the particle hits the screen, but rather at a later time period. In that solution, what happens later can change the wave function probabilities so that when the wave function finally collapses, the particle does what it should do based on whether the which way path information is saved or erased. What are your thoughts about what I wrote above? Also, wondering if you could make a video on wave function collapse, and should there always be wave function collapse when a particle hits a screen when its entangled pair can still be measured to determine / not determine which way path information. Again, thanks for your great videos! They are my favorite along with Arvin Ash on youtube!
This is one of my favorite topics. This was a great explanation (the best I’ve seen), thanks for doing this. I didn’t know that a photon could become an electron / positron pair…. Cool. However, I like to think that God doesn’t play dice with the universe, so, I am wondering if some day we will figure out something we have been missing and look back and think wow, how did we miss that! :)
There are so many theories, one which is almost a joke is called "one electron universe" where everything can be made by a single electron moving backward and forward in time. 🤯
Hidden variables would allow for determinism. Bell experiments rule out local hidden variables, but do not rule out non-local hidden variables. Some sloppy descriptions of Bell's inequality fail to make this important distinction.
Taking the theological route on this question, do you think God holds us accountable for our actions? If the universe is completely deterministic, then your every thought and action could have been predicted before you were even born! Divine judgement wouldn't make any sense unless some aspect of our decision-making process is genuinely unpredictable.
@@flexico64 It’s the greatest question of all isn’t it?! Me sitting here debating whether or not to reply to this question could literally have been planned out 13.7 billion years ago! Including my hesitation to google how old the universe is. Hmmm. Kinda nuts.
So that means when we turn into photons we'll have eternal life? Cool message for Easter 🐇! I'm still confused about how you entangle the particles. Maybe it's a mathematical reality but not physical, as you pondered. So much more to learn! I feel like we're just starting to understand physics.
@Bill Allen - "I'm still confused about how you entangle the particles" if i remember right, the way they do it is they fire gamma rays at a solid substance... what substance i'm not sure... i think i read somewhere once that they use a certain type of crystal, because their quantum modelling had showed them that certain crystals lend themselves more to pair production than other substances, because of how the atoms are arranged (but can't remember for sure on this :p) the gamma ray fired at the object needs to have at least 1.022 mega-electron-volts (MeV) of energy, because an electron has 0.511 MeV of rest mass energy... and since they are attempting to create an entangled electron-positron pair, (the positron also having a rest energy of 0.511 MeV), under mass-energy equivalence relation it adds up to 1.022 MeV being needed as the initial input energy on the gamma ray they are firing at the crystal or what have you Google mentioned that the gamma ray has to approach a nucleus for the event to take place, to fulfill conservation of momentum... the nucleus receives some sort of recoil energy from the event i could have sworn i once read somewhere that pair production can sometimes occur in the vacuum of space without any nuclei nearby, but i can't remember where i read that and i want to be careful not to spread misinformation on accident hehe... so not sure on that part :p i believe under many circumstances the positron that gets created almost immediately annihilates itself and whatever it crashes into, because it is a form of antimatter... and when antimatter crashes into normal matter both particles often turn into a photon and radiate away but i guess for these entanglement correlation experiments that Nick Lucid is talking about, the scientists have figured out some way to get the positron to live longer and corral it away into a slightly safer situation maybe? i'm not sure... thats just me guessing... how they would have achieved such a feat, if this guess is correct, is itself very fascinating to me... because crystals, and all solid objects for that matter, are probably very dense... and just a giant thicket of stuff for a positron to crash into and transform into a photon... so getting a positron to survive for a longer time is probably very difficult to do lol maybe anyway :p
I’ve always wondered about the idea of measuring one of the particles as up/down and the other as left/right so it was very cool to see that addressed.
I've always thought it's a bit easier to think about entanglement in a looser definition of particle. Once you have a multi-particle system, you have to describe them as one wavefunction, and so thinking of entanglement as this weird particles talking to one another faster than possible seems a bit unnatural. Instead, I like to think of it as two particles combining into one sort of 'new particle'. I'll admit that this isn't the most rigorous argument, and there are likely issues with it, but it's helped me stomach the weirdness of entanglement a bit better. Also, I'd love to see a follow up video about how closely related entanglement is to factoring. It's a beautifully simple concept, and it gives nice intuition for why checking for entanglement is such a computationally difficult problem.
I have a pretty annoying question: how can we actually do the experiment you outlined? How do we ID and preserve entangled particles, send half of them near the moon, and do the measurements in a time-synchronized way? A bonus: how can this be interpreted via the pilot wave interpretation?
Yes, a Chinese group separated entangled particles one in a satellite in 2020 - look it up if you want the details. Pilot wave theory turns out to be a bit redundant of an explanation, but it predicts all the same probabilities as standard QM.
Great video sir. Very well done. Key words in the video " lower the expectations " Tunnel vision is a serious problem for humans.. Your humbleness is both refreshing and hopeful.
Is it possible that universe is expanding in true emptiness (where nothing exists not even space) by obeying the second law of thermodynamics (high energy flows towards less dense energy)? Because if it's possible, we don't need dark energy to cause the expansion, and it also leads to the Big rip.
You have the ability to explain such matters like no one else I know, man. I absolutely love your channel! Regards from a quazy fan living across the hemisphere.
I just found this channel a few days ago and am slowly going through the backlog. :) As a fellow Michigander (well, Michigoose if you want to get technical), it's pretty neat to see a more-or-less local as a successful UA-camr. As for being crazy in Michigan, well, aren't we all Michugenah here? (I am also such a dork.)
I'd like to believe I turned Kyle on to your channel. He was doing a list ranking of science channels, and tragically you weren't on the list at all. I told him about your channel and he commented like he's not heard of you. A bit later you were mentioned as someone who has a video on the topic he was talking about. I did do a quick scroll through the comments and seen a few others mention you, but I was the first. I don't really know if he had known of your channel or not. But I am taking full responsibility. I like the idea of being the person who made this match possible. Though it likely it wasn't. Keep doing what you're doing. You're doing it right. Appreciate ya.
🍴 I have my fork ready for classical physics, but the set came with a knife that I'd like to cut to the heart of quantum mechanics with and really understand what's going on.
I like the Multiverse explanation of entanglement the best. Every observation we make takes us instantaneously into a different universe within the Multiverse. This doesn't violate the speed of light being the universal speed limit since we can't use quantum entanglement to send matter, energy, or any form of information faster than light.
I have struggled for a long time with the notion of Bell's Theorem. I understand that Bell's Inequalities are violated, but in my searches I have had little luck warping my brain around why it is a theorem, and why we shouldn't natural expect to see trig equations like sin^2(theta) and cos^2(theta) when dealing with the probability of a random spin angle having an up or down component in its vector in a system of hidden variables. The math just doesn't feel right, and I would like a more in depth explanation of just the math without the rest of entanglement and quantum physics involved. Keep up the good work, I don't always agree with the interpretations of the results, but I find the experiments themselves fascinating, and I really enjoy your videos.
yay! i love these videos, been watching all of them all in and out of order by upload date. i watch them all a whole bunch but turning the playback speed way down really helps me fully understand the videos. the watching of these videos is a whole ass experience. i found slowing down the playback rate a ton on these makes for a ‘magical’ experience. ur really immersed in what the ships AI is showing u. these videos are awesome although i still have no clue if a photon is a physical wave or a wave of probability lol
In the fabric of space where mysteries roam, Entanglement weaves its intricate tome. A phenomenon profound, a cosmic ballet, Where particles dance in a quantum display. Entangled they are, in a quantum embrace, Bound by a bond that time cannot efface. Though separated by vast cosmic spans, They dance in unison, defying our plans. But how does it break the universe, you ask? In its enigma lies a daunting task. For entanglement whispers of connections unseen, A web of existence, where reality's keen. Break one entanglement, and chaos may ensue, A ripple effect, tearing reality askew. For in the quantum realm, where uncertainty reigns, Entanglement holds the key to what remains. It challenges our notions of space and of time, Revealing a truth that's profound and sublime. Entanglement breaks the universe apart, To show us the secrets at its very heart. So ponder this mystery, this cosmic affair, Entanglement's dance, beyond compare. For in its embrace, the universe bends, Revealing the wonders that time transcends.
Okay, I am really old and not a Physics master, so be kind! It seems to me, based on this video, that the direction of the super positioning of these little suckers changes VERY quickly - seemingly instantaneously. If that is the case does measuring the direction at any one instant really mean anything? The "instant" you determine a direction it within an an instant it has changed to an unpredictable new position. Help me to understand this! EACH of your videos are amazing! You are a true teacher!
That's the fun of it all! If it's in a superposition state it could be spin up could be spin down who knows. BUT if I measure it to be spin up, it will stay spin up. Once the measurement is done we can deterministically say it will remain in spin up.
@@jimmypizza9854 My point is, does it really matter? Once you measure it, it has changed state. Also, some think that measuring something influences its nature. So, once again - what is the point of measuring it! Besides, it is changing state so quickly it is _essentially_ in two states at the same instant! Help!
Excellent video! I’m a big fan of QM and your stuff always brings a new perspective and often new clarity to these topics. However, in all my reading and viewing, I’ve never experienced a good explanation for HOW entangled pairs are produced. Any chance you can make a video about how “entangled particles are produced?”
I can't read the math, but seeing it still helps me grasp what is going on. I feel you are part of a new wave of science communicators that brings this aspect to audiences in a way no other popular presenters have done.
i don’t understand it at all but im glad there are people who basically prove things with math, somehow. like who knew math could model something so complex like the cosmos.
@@RoscoeDaMule the unreasonable effectiveness of mathematics
You could read the math here. It really isn't that hard. Just a little effort. It is using Dirac's notations which is just a fancy shorthand for linear algebra. Super cheap book called "A Student's Guide to the Schrödinger Equation" ISBN-13: 978-1108819787 or ISBN-10: 1108819788 which breaks it down pretty quickly. If you don't know what Linear Algebra is... it is not hard at all like maybe calculus is for some people. Linear Algebra does a lot of Matrix operations. It mostly might just "seem hard" because maybe you've never seen it before... but once you become familiar... it becomes like everything else. Who knows, you might like the taste of it and pick up a physics addiction.
BTW Paul Dirac was a ridiculously powerful mathematician in his own right. I would argue that he potentially was the greatest physicist of the last century. With Einstein coming in second place.
I don’t see the point of so called science communicators. If you cannot understand the maths then you can’t do anything with this, in the best case scenario knowing these theories without their formulaic with construction is useless trivia and in the worst case scenario causes people to think wrongly and draw bad conclusions which is why we have so many Deepak Chopra types running around.
@@peterader3073 Do you not see a point for economists to communicate economic conditions and lawyers to communicate legalities, too? A lot of people want to stay in touch with modern scientific knowledge without being a scientist who fully understands it.
"the details shall be left as an exercise for the reader" is a frustrating cop-out that assumes the reader (or viewer, in this case) even knows wtf to even do to complete the so-called exercise. Nick, I am absolutely grateful to you for NOT leaving that exercise to us, your viewers, and not only working it out yourself, but showing us your work and setting an example.
I mean, keeping in mind the intended audience is key. There's a big difference between an advanced textbook on quantum theory that assumes the reader has sufficient mathematical background to work out such derivations, and a UA-cam video aimed at a general audience. If the video/book/whatever is aimed at a general audience, as Nick's videos are, it would make little sense to say something like that. But if the work is aimed specifically at advanced students of quantum theory it wouldn't be so unreasonable to assume the reader is capable of doing such derivations.
That said, personally, I don't like the practice of saying "the details will be left as an exercise for the reader" because it can come off as kind of lazy on the author's part -- it'd be better to just make it one of the questions at the end of the chapter.
or adding, "somehow, it works out"
@@Lucky10279 exactly, it is lazy
@@Hyporama lol
I have all the respect in the world for a physicist whose style is the opposite of the style of those who say "the details shall be left as an exercise for the reader."
Damn right. Show me the equations - all of them!
Yeah. All respect to a teacher who understands what students are going through and hasn't forgotten his own days as a student.
See the channel "physics unsimplified" for the gory details -)
I love the "to the timeline!" segments-- you're using the consistent histories approach to teach quantum cosmology to humans. It's great!
That line near the end was the most clear and understandable thing I've yet heard from this channel. "We need to relax our expectations." Wisdom for life in general.
It's impossible to overstate how incredible these videos are. Thank you for making them
One of the most Empathic Videos i ever saw just came out: "Why do I Care?' by 'Belief It Or Not'. Together with the GOP-Videos of 'Some More News', its quite amazing and best coverage of the Attack on Woman-Rights and other things, i know.
For those who wanna be updated and those that have Empathy (a combinttion that will make
you wanna know about the current Abortion-Right Chaos), this is for you.
@@nenmaster5218 uh thanks ig
"quantum mechanics is not magic" ----> proceed to explain how quantum mechanics is basically magic.
Magic is just science which we don't yet understand, think about it, fire was also magic thousands of years ago
@@MasterMind75427 I use to say that magic is just science that doesn't work, so by my definition quantum mechanics is not magic, just mind blowing.
He's referring to the "conscious observer" trope - that somehow it's our minds making it happen.
@@DavidHeizer An "observation " can be done by anything. A random particle interacting with the electron would force it into a state, thus, collapsing the wave function, and "making it happen"
😂❤
Danke!
Bitte!
"conservation of energy shall not be violated" is the MOST ICONIC line I've ever seen on any youtube channel
It's just right next to my heart to TO THE TIMELINE!
Funny thing about a lot of these QM explanations is that even though QM itself being unintuitive is true, the really unintuitive part to me is how these experiments are physically performed. From the usual diagrams it's often pretty hard to imagine how these detectors work, or how they manage to get one entangled particle into space without, well, doing the particle equivalent of dropping an egg you were carrying in a spoon with your mouth. :P
If you read the details of the experiments performed and how the machines are built you can get an idea as to how they work and how they are used to perform a test. They're tools that are expected to give precise values about a specific aspect of reality. I suppose you can say that they're very advanced tools that not many people can think of and even the people who thought of them had to spend a lot of time thinking about them, testing them, and getting them to perform as intended.
I think the record for entangled particle separation is several hundred kilometres? They used fibre optics and phased photons or something? If you think about it some quantum particles are huge, hundreds of kilometres across - I still can't visulize how radio wave photons show quantum effects (but they do).
@@jitteryjet7525 I think we're misunderstanding "size" as it refers to waves and their interaction with things. For example, audible sound waves can be up to 17m. How does the human ear detect that without rupturing? Radio waves can be kilometers in size, yet are produced and detected by pieces of metal mere cm long.
I think the answer is that the detector (or interacting object) simply takes a portion of the energy from the wave, and the rest continues on. That is, it takes from the *amplitude* regardless of the wavelength, and all it needs to be is in the path of some photons (or particles of air). (Amplitude is a silly concept for photons, though, as all the energy is described by the wavelength, but then how does Amplitude Modulation work? I think what you could say is that some photons are absorbed by the detector, transferring the energy to the wire which then replicates the absorbed waveform, which is comprised of many photons of slightly different wavelengths, into an electrical signal). It's also important to remember that photons (like all quantum objects) exhibit wave-particle duality. They are a spread-out wave when it's convenient, and they are a pinpoint particle when it's convenient. And sometimes they are both.
Also, something I think people forget: the wavelength is literally that. The wave *length*. As in, the distance from one peak to the next. Along the direction of travel.
Is any of this making sense? I'm confusing myself here.
@@RaunienTheFirst I am not misunderstanding size. My point is the exact position of a particle can be somewhat muddy eg if you don't know the exact position of two quantum particles, how can you say they are in separate locations? They might still overlap in space (somehow).
That frustrates me , because I have never seen even a basic explanation of how these detectors work , even though they play such a important role .
The explanation of how the detector works in this video is far too simple .
I kinda just assume they are using magnets , since spin is just a magnetic particle . If they are using magnets then why wasn't it considered as a potential hidden variable ?
You make a lot of great videos but this one was exceptionally good.
I think this was the first time I've ever seen anyone actually points out how you get an entangled pair of particles. Thank you!
This may be the best video explanation on Bell Inequalities I've ever heard, (and I've heard a few).
Good job here; exceptional.
Thanks! 🤓
@@ScienceAsylum My money is on wormholes connecting the particles, also known as ER = EPR. In Einstein and Rosen paper about Einstein-Rosen bridges, they concluded that wormholes would instantaneously disappear the moment they are created. Their conclusion is correct, but for static wormholes. The problem is that Einstein had his mind locked in a static Universe, because that was the data on the time, and he did not think of moving space, which ultimately caused his "greatest blunder". In order for a static wormhole to be stable, it requires magic, he correctly concluded. But if the wormhole is rotating, it has been proven that it remains stable and does not need any sort of appeal to magic to keep the throat open. I strongly believe that entangled particles share information through rotating wormholes.
Is it bad that I don't have a clue what a bell inequality is, despite having watched the video.
@@fahrenheit2101 No, it's just the name of the experiment he was describing. The important thing is the principles. Names are just names. However, you can certainly use that name to search "Bell Inequalities", and now have an excellent primer on the topic.
John Bell had amazing contribution to physics, but most people probably haven't heard of him.
@Lady_Sugar Principles in science is equivalent to Axioms in mathematics. This are statements that are accepted to be true because we have not found counter examples. Laws are derive from mathematical models of our universe and they get broken in cases where the mathematical models break down. For example dark energy violates the law of conservation of energy because conservation of energy is derive from a mathematical model that has time translation symmetry which is only true locally but is not true in the cosmic scale.
This is a very well written episode. It may not seem that way to the non-expert ears, but the words are chosen so correctly and so good to reflect a correct and pure and consistent understanding of QM and to connect the well- established mathematics of QM to its philosophy and the connection between the two (which was not appreciated for a very long time in the history of QM, until John Bell's great contribution) in a clear, intuitive yet precise way. Well done Mr. Lucid.
Also those looking for further material, can search for Prof. Leonard Susskind's lectures on what he calls "ER=EPR": the hypothetical connection between wormholes (ER bridges) and entanglement (EPR)
Once more Edwin Hubble popped into my mind:
"Equipped with his five senses, man explores the universe around him and calls the adventure Science."
Thanks a lot for another of your really fantastic videos! I like them all.
Three things.
1)Please do a video on superdeterminism
2) Statistical independence is something that Bell assumed, but such assumption can be challenged in quantum world
3) ER=EPR
There is a possibility that doesn't violate locality: no matter how far apart the measurements are, the two observers still need to meet and compare notes locally. It could be that at the moment of measurement, the observers themselves become entangled with that superposition too, and then become entangled with each other when they share information. They don't experience the superposition (i.e. their memory remains consistent from the moment of measurement until they confer with the other observer) because their memories are also part of that superposition: the superposition is the set of all states that are self-consistent over time and space, and any verification of what state it is in also entangles the verifier, making any possible perception of the state also self-consistent over time and space.
This is how "Many Worlds" really works, and why it's a misnomer. It's not that there are actually several different universes that somehow physically split apart and duplicate matter somehow. There is only one universe, but that universe is a constant superposition of all possible self-consistent states, re-entangling with itself over and over again, and our experience of the universe is just one of these self-consistent states within the broader superposition.
(a better name than "many worlds" imo is "Eternalism", which is a concept from the video game Warframe, named after the philosophical theory of time. Basically, Eternalism in Warframe is the idea that the past and future exist as a solid and unchanging block of all possible states of the universe, and that our subjective experience is like a single path winding through that block, with each "measurement" or "choice" changing the direction of our subjective world-line but not the solid block of possibility itself. In other words, Schrodinger's Cat IS both alive and dead, but either way Schodinger will only remember it being one of those, and so will you when you ask him which it was, because you and Schrodinger and the cat are all entangled with the state of the quantum particle.)
¡Gracias!
Wow! I've been reading on EPR Paradox for a long time but this is one of the best explanation for the resolution of it. So hard to get your head around all this without having a solid understanding of the math behind it. Thanks, Science Asylum for making it accessible for us, mere mortals.
I can understand dealing with a pair of particles in the lab, but here and on another world, how do you do that??? There's no directory for entanglement...
@@billallen275 what
@@billallen275 wym there's no directory for entaglement?
I really appreciate you bring free knowledge for people who are starved for education, quantum physics are difficult
I love when in 1 episode you're:
-showing some super complicated stuff
- explaining it
- and doing this whole stuff in a funny way
One of the most Empathic Videos i ever saw just came out: "Why do I Care?' by 'Belief It Or Not'. Together with the GOP-Videos of 'Some More News', its quite amazing and best coverage of the Attack on Woman-Rights and other things, i know.
For those who wanna be updated and those that have Empathy (a combinttion that will make
you wanna know about the current Abortion-Right Chaos), this is for you.
This is the clearest explanation i've heard - plus it gives an example of how entanglement is generated....most explanations start off with they just are.
The conclusion about "communicating faster than light" we get only in certain interpretations, but in MWI we can still save locality, as Sean Carroll nicely explains in his book. In each "world" changes in state propagate not faster than light, then during the measurement you just learn in which world you're in. So beautiful.
I guess it's a case of non-local hidden variables which aren't ruled out by Bell's experiments.
Yeah, many worlds, ties everything up very elegantly. No more troublesome non-realism or non-locality, no more hackish contradictory Born rule, no more measurement problem. But, like, it sounds stoned, so let's just keep all of those contradictions. -Copenhagen
ありがとうございます！
I'm a 3rd y. physic student and i just studied this, and I mean just before opening youtube. You make it very clear thanks to visual represantation.
Thanks!
I think you forgot to mention that Bell experiment doesn't invalidate hidden variables, only LOCAL hidden variables. A non local hidden variable model is still possible
Exactly. It’s likely the entangled state is one state in 4D appearing as two particles in a 3D slice - so our classical sense of ‘locality’ needs an upgrade.
That's what "breaking the universe" means in this video. Real but non-local.
I briefly mentioned examples of this in the summary at 8:57
@@ScienceAsylum Yeah I recognized the De Broglie wave pilot. But again yeah I think the conclusion of your video is a bit misleading because it makes it seems like hidden variables are definitely a goner whereas it is not the case
@@ScienceAsylum some have already asked about this, but I will too: what is your response to the Sabine Hossenfelder's video/thesis about superdeterminism?
In it, she said that Bell's theorem has three assumptions about theory in question:
1. It is deterministic (so hidden variables exists)
2. It is local (so it fits with GR and so on)
3. The Statical Independence is true
She said, that most physists had BELIEVED in this third assumption, without real evidence for it, and they managed to forgot it's even in there. However, she says, if one discards Stastical Independence (like superdeterminism does), then the Bell's theorem no longer holds and one can get local AND deterministic version of quantum mechanics just fine.
I have to say, she's got the point about the irrational belief in the Statistical Independence, as you for example did not even mentioned it, so you've created the impression in the viewers that local and deterministic theory is just impossible, period.
I'm so happy to have found your videos. After watching so many others, I finally feel my doubts are eroding.
That's great to hear! I'm glad my videos are helping.
I always think of “hidden variables “ not just as the variable being hidden, but the whole logic behind the variable being weird and unintuitive, not just an unknown number.
It is predetermined to be up and down, but not the value itself is predetermined, but the whole equation, along with its logic, which is weirder than QM itself.
I need to think about what you said. Could this relate to the many universes interpretation of QM? Or is it an alternative to that?
Wait so are you saying that what we think is "random" is really not but maybe is just a super complicated function that we dont understand yet?
@@shuhulmujoo “super complicated function” is still just a function, which is longer. What I’m thinking about is complicated in another level.
@@juzoli Another level? What exactly do you mean by that?
This is real gift, to be able to break down complex concepts into bite-sized chunks, seasoned with a generous dash of humor.
Normal people 99% do not need quantum mechanics. But if you are little bit crazy or you want something new to learn, then yes. Thank you.
I only understand a small portion of the stuff you talk about on this channel but it fascinates me to no end!!! Thank you for taking the time to explain these things to regular people! Haha
Have you seen sabine hossenfelder's videos on quantum entanglement and hidden variables? she seems to take quite a stance against the version you propose here.
My guy you consistently find amazing ways to explain these ideas. The way you summed up Bell’s basic premise really helped me understand how someone could come up with the idea, but I’m glad I don’t have to do the math to work it out.
I was a bit confused because 7:12 says there are only 6 possible outcomes. But it looks like binary numbers to me, having 3 bits would give you 8 possible outcomes.
You could add
{+a, +b, +c}
{-a, -b, -c}
Does that mean that spin has to be different on at least one axis when measuring on 3 axis? If so, why?
{+a, +b, +c} and {-a, -b, -c} are options in general, but not in my specific example because of the way I oriented the detectors. It's impossible for all the signs to be the same when they're all 120 degrees apart.
I really think that this channel sets the trend for science communication on the internet. I hope that more and more of these channels gain popularity and prevail over the silly psuedoscience that seems to be so popular right now. This channel shows people how science is way more fascinating than coming up with some magic story, just to fulfil the need to feel special. As shown in this very upload, the universe is special and so are you down to your very quarks! I do worry that people are hesitant to understand science as if 1 concept goes against their presuppositions, they revert to science denial and to me, the most dangerous cultism facing our species.
0:43 Microseconds ago, the high-energy photon lived in a stable and massless state. Then everything changed when a nucleus attacked.
Thanks
Could it be that separated quantum entangled particles are still “close” to each other across a higher dimensional space?
That would be the "wormhole" explanation at 9:27.
I don't think this is likely. Single particles that are not entangled also display the same sort of weirdness in the double-slit experiment, and in that scenario you can fire them one particle at a time launched at random times and still get interference - how would the higher dimensional space or the worhhole know where to go to be "close to" the previous or next particle in time. It doesn't even need to be in the same space, you could build 5000 machines and fire only one particle through each before disassembling them and still get the interference pattern when you merge the results. It just IS probabilistic.
@@Tony-dp1rl i like your funny words magic man
This is the clearest explanation of "hidden variables" and Bell's Inequality I have ever seen.
Maybe the most unambiguous explanation currently on UA-cam of QE and the Bell inequality experiment and how it resolves the EPR paradox. All that in less than 11 minutes. Bravo!
I'm so glad to hear Nick say it out loud. "Entangled particles can interact faster than light."
Can anybody answer this question:
Is every superpositioned particle (with or without entangled fellows) oblivious to locality before it's "measured" into 3d?
Lmfaooo, faster than the speed of light. They do not interact faster than the speed of light. I solved QE 3 years ago
Congratulations, you're the first to show us which maths were behind the whole thing! I've looking for this math quite a long in the whole internet, and I've even found a page with mistakes in the math! Thanks a lot!! As you say, Quantum is not magic, but rules (and calculations) ...
Thank you for the great explanation! It leaves me with a few questions - for the three angles, is there a minimum degrees apart? Instead of 120,120,120, what if they were a billionth of a degree apart, so basically 360,0,0. Would we still see 50-50? If so, can we really tell if two measuring devices very far apart are within a billionth of a degrees off axis? If not, then wouldn't all measurements be 50-50? The basis of my question - two measuring devices can not be exactly oriented the same, so wouldn't all of them return 50-50, even if we think they are aligned along one ais?
cos(theta/2)^2 is what you see.
Too often in explanations from various science communicators I don't hear about higher dimensions being part of the explanation for quantum weirdness we observe. So THANK YOU, Nick, for giving that credence and a nice quick primer.
The first time I heard about entangled particles was in high school, and Instantly thought, the particles were just stretching space in between one another. I thought to myself that if that was the case, then we could one day potentially measure how far space could be stretched on that level and at some point maybe even notice a delay in the particles. Since we haven't actually measure them in the vast distances of space.
I came to the conclusion that entangled particles are actually one object. Think of it like how your three-dimensional hand can touch a two-dimensional sheet of paper in two or more places without directly touching any of the two-dimensional space in between.
I'm pretty sure the idea is congruent with quantum theory. I just have no idea how to measure the topology of an object with 4 or more physical dimensions.
@@Grizabeebles Look up EP = EPR conjecture from 1935.
As someone who has a background in Physics, I always went along with the accepted point that the randomness within a quantum entangled system prevents FTL communications. I recently read a book 'Cracking the Cosmic Code' which actually shows that the randomness is not a restriction at all. It now opens up the distinct possibilities of FTL communications.
This might be both the shortest and easiest to understand exposition of Bell's Theorem.
Thank you for your channel. I conduct outside the box experiments on my page here and anytime there is something I need clarity on I come to your site here and I always find an answer that is laid out in such a way that anyone can understand the workings of it.
Mr. Lucid,
What is your stance on statistical independence when discussing Bell's Theorem? For example, the arguments brought up by Sabine in her super-determinism video.
Thanks for the content
Sorry to intrude but superdeterminism implies ‘suppose the two detector angles are chosen at random’ no longer holds, and so 55% would not be the expected outcome. As for what it would instead be, I’m not sure.
@@anywallsocket yeah, but that's the point, ins't it? That it's an assumption of the experiment which arguably might not hold, possibly invalidating it's standard interpretations?
@@user-sl6gn1ss8p well at the end of the day we can make our decisions based off of local noise (highly random), so previous correlations break down and superdeterminism starts to suggest that everything is always correlated, at least somewhat, but that starts to sound unfalsifiable and therefore unscientific.
@@anywallsocket Nothing less than SuperDeterminism is humble enough.
We don't know what we don't know.
@@jeffrelf this.
6:43 Very nice explanation of the Bell Test!
7:21 Especially the notations of the possible outcomes! Very elegant, and probably the best I've seen in the last couple of years!
I see clearly now why Hidden Variables are rejected, because they would require the test to yield 55.6% opposite outcomes, instead of the 50% observed!
It depends what you define as "interaction", but I personally would be careful calling it "faster than light interaction". After all you can't transfer any information faster than light with this. If you have two entangled particles A and B, then you can do whatever you want with A, you will not be able to detect that "something" happened to A by just observing B.
Indeed QM does not describe the occurrence as an "interaction", nor causation. The formalism is "talking about" the "effect" of conditionalization on correlated systems (in the traditional QM parlance that is the collapse of entangled states). Note, as Einstein also pointed out, that we can make a similar consideration even without considering correlated (entangled) systems, but just one system, i.e. across alternatives (e.g. when alternatives are across a space-like extension, in respect to relativity, conditionalization over the alternatives has the same behavior as conditionalization of space-like separated correlated systems). This is, though, the "normal" behavior of conditionalization in a probabilistic theory, e.g. the relation of conditionalization and relativity in QM and C(lassical)M is the same, be it for correlated systems, or across alternatives of a single system.
The issue with QM emerges when we combine this with the indeterminacy of QM (which is in fact a property of quantum logic, as the algebraic structure of quantum probabilities), and it is about what we can accept as a warrant of the results that factually match the prescriptions of QM formalism.
It is a novelty of QM respect to CM because the latter, and at its core classical logic, admits the deterministic formulation of the probabilistic theory (we are used to give the deterministic formulation of CM for granted, then eventually "generalize" it with a probabilistic formulation, but epistemically the correct reasoning is the other way around -- knowledge is always limited, we always have limits of resolution). The fact that in CM/CL the theory admits the deterministic formulation is what "trivializes" the probabilities to being purely epistemic, i.e. in the indefinite limit of uncertainty removal, the theory is informationally complete and deterministic, that is, it "trivializes" probabilities in the sense that there is no proper information in the probabilistic layer of the theory since all the information is in the deterministic one. Alternatives and correlations are non-local notions both in CM and QM, while the mechanics, i.e. causation, is local, also, in both theories. The difference is that the probabilistic formulation is informationally trivial in CM, i.e. the information is complete in the deterministic formulation of the mechanics, which brings with it that it is locally-complete for CM. In other words, alternatives and correlations are warranted by the deterministic formulation of the theory, which incidentally is local.
This is not the case for QM. Quantum logic has different atomization properties, that exclude the existence of the limit of indefinite removal of uncertainty, which is essentially the indeterminacy property of QM (the limit is not unique, as the limits are the basis, and between basis indeterminacy relations holds). QM does not admit a deterministic formulation of the theory as it stands.
Thus, the information encoded in quantum probabilities is not trivial, in particular in respect to alternatives and correlations (entanglement is holistic correlations), which are not local, resulting in the fact that quantum information is not locally-complete.
This is what EPR is evidencing to argue that QM is incomplete essentially "because it must be" locally-complete. Is this a correct claim or is it a prejudice stemming from being accustomed to classical physics, and determinism in particular? Does QM propose to us a different way to look at the universe?
I agree with the author of this video when he says that we need to relax our expectations. I even consider this an euphemism, I think we need to start thinking that it is QM that sets our expectations, not that we have to understand it by what we expect (on what ground?). If QM is our fundamental physical theory, that is how we should approach it: "understanding QM" then means "understanding by mean of it".
In any case, FTL causation is dismissed in the EPR argument. I am not aware of viable proposals based on it. If there are, they are in competition with other approaches. Furthermore, as noted above, QM itself does not employ, or "talk about", FTL causation.
In my view the entangled particles are in a way connected meanjng there js no transfer of info, they are in a way one.
The best explanation of QE on UA-cam. As for all the topics covered.
Have you seen Sabine Hossenfelder’s video on super determineism? She says that Bell’s work assumes statistical independence. This is a fine assumption, but it is just an assumption. It seems that no one questions the assumption because people want it to be true and everyone thinks it’s true. That’s understandable but it’s not science. And there is a long history of very bad science based on what people want and what’s popular.
Personally, for me super determinism seems a much simpler description of the universe then all the contortions people go through to explain entanglement.
Yah she poked plenty of holes in the common interpretation of bells theorem. But youtubers gonna get more clicks if they claim magical explanations, so much for science...
Maybe Bell's experiment shows that the properties that we formerly labeled as "up spin" or "down spin" were never literally up vs. down. They were inward vs. outward. Under this arrangement, the inherent chirality of the universe is preserved.
Question: in your experiment what is the state of the two particles according to an observer that knows nothing of the outcome of the observation? Are the two particles still in super position according to them? Then if they never interact with the original observers can they measure the spin and see a different outcome? If so, does this mean that the observers have different realities? Then they could come together and share their realities and realize that they are incompatible?
This is a surprisingly good question. Not sure that it can be answered, even in principle. I think it lies at the heart if the Many Worlds theory (of which I am not a fan, although I understand the attractivenes of it, because of this question).
That's not what I am getting from the video though. The particle spins in both directions until it interacts with an observer.
The observer isn't necessarily "conscious", "sentient", or "sapient", if that's what you meant.
As far as I understand, any interaction where the particle's state is relevant with outside systems causes the wave function to collapse.
Ya he makes that clear in the video that the observer does not need to be conscious. I was wondering about the relationship between separate observers. Do they need to be connected in some way for the observation by one to affect the observation by another. Kind of wondering if there is an objective reality. You seem to be saying there is for sure but how do you prove that?
Another home run, Nick 🙌 Also at the risk of sounding like a shopping bot - I truly did just buy 4 of those shirts for our family. Gratuitous promotion works!! We're all just big fans. Thank you 🙏
This helps from the previous video when I asked about this exact thing!
I am wondering if you could maybe in the future do a video on the "Light polarization paradox". Where if you have 2 lenses at 90 degree angles, it blocks out all light, but if you insert a 3rd lens between them at 45 degrees, light can start passing through again.
That is not a paradox, and can be explained by classical electromagnetics: light is only blocked when its polarization is perpendicular to the filter, when you have 3 lenses, each 45 degrees apart, this never happens.
I'm already working on that video actually 🤓. (To be honest, I wanted this video to be that video, but I knew it wouldn't be done by the deadline.)
@@anywallsocket Correct me if I'm wrong, this happens only when all three filters lie on top of each other and act like one filter?
If I take 3 polarized filters angle them at 45 deg but put some distance between them?
@@ScienceAsylum awesome! It would be nice if you could talk about the polorizing filter-particle interaction. For particals that pass the filter the filter changes the particle's spin direction. It's possible that you don't need hidden variables to have locality. If both entangled particles pass and both were measured in the same direction then they were probably close to the filter's orientation. If you measured in different directions then only a very small percentage of times you get that both passed. In that case the one that passed while being far from the filter orientation can become closer to random 50% depending on a local partical-filter interaction
I think you mean polarisers rather than lenses? An interesting thought experiment is that you can continue the thought experiment beyond 3 polarisers - keep adding polarisers at just the right angles and you can get smooth, continuous rotation of the light polarisation with *zero* loss.
Bonus fact, such devices are called Faraday isolators or polarisation rotators (depending whether the device is non-reciprocal/magnetic or not). Both are used routinely in optics labs.
I can't stress enough how cool your content is. Thanks Nick! I love your channel. And it's okay to be a little crazy!
The funny thing is that among the explanations you floated towards the end, I’d order them from least to most crazy-sounding as follows: “pilot waves (de Broglie Bohm), worm hole (ER=EPR), many worlds (Everett).
1. But to actually resolving confusions about entanglement, Everett probably does the best job.
2. The pilot waves doesn’t handle relativity and quantum field theory too well as far as I can tell, which if true is quite a bad problem. The basic idea is applicable to other wave problems, completely unrelated to quantum mechanics though.
3. There is some teeth to the wormhole idea as a thought experiment to probe quantum gravity. So it probably won’t come as a surprise that this idea hits on some pretty advanced physics which this kind of video can’t give nearly enough tools for a proper discussion. My comments won’t be terribly illuminating either. I will say this; To the extent that there is a connection between wormholes and entanglement, it’s not obvious that wormholes should be though of as more ‘fundamental’ object. It might instead be that entanglement is the more fundamental notion and that some special quantum states with lots of entanglement configured in a particular way is how spacetimes and wormholes are described quantum mechanically. Another possibility is that it’s better to think of it in terms of a correspondence between two equally good ways of describing the same physics. Even if wormholes isn’t the explanation of entanglement, I’d bet this line of reasoning is more likely to be important for fundamental physicists than the pilot wave idea is.
In the Many Worlds Interpretation, the branch occurs at the moment that the wave function collapses, right?
So to clarify... if we're separated by a great distance, you have one particle in an entangled pair and I have the other, we're still in the same reality.
As soon as you measure your particle, we now have two worlds.
In one of the worlds, you have an up particle, and I have a down particle.
In the other world, you have a down particle and I have an up particle.
But reality doesn't branch until you make the measurement, right?
@@cykeok3525 No, not really. Many worlds doesn’t have collapse. That’s one of the main features. Time evolution only ever uses the Schrödinger equation and nothing else. Locality of interactions is better encoded in QFT, and more details about the specific laws of physics needs to be imposed. If you do that however and then lay out the ideas of MWI branching is local.
Its better to think of it as systems becoming entangled with each other. Say two particles are entangled. Then the measurement device by some interaction becomes entangled with the particle close to it and then you becomes entangled with the measurement device and so on. It’s not like the world “splits” all at once. Measurement is a local process and affects nothing far away. At least that’s the idea.
More details are needed to make the logic clear this is the extremely rough version of it. The takeaway is MWI is just plain old quantum mechanics without the measurement collapse postulate. In principle, nothing more, nothing less.
Best intro video I've seen on quantum entanglement
Couldn't it be possible that the entangled particles just share the same "seed" orientation determined when they were entangled which then evolves according to some predictable process into the observations?
My thought is based on the analogy of a 2fa code in an authenticator app, you share some "key" which is then factored into an equation that turns it into a pseudo random number, but it's a predictable value, so we can use it for authentication, just compute the code once on both ends and compare. No need to transfer data faster than light at all. The only difference between this analogy and entanglement is that rather than resulting in the same value after calculation, it's the negative of that value instead.
If there is a seed, then the outcome of all three orientations is determined for a particle, exactly as shown at 7:20. So, a particle would have a "hidden" positive or negative value for each of the orientations, and in its entangled pair they are all the opposite. If you do the math, statistically you should get different signs 55.6% of the time. Here's a summary:
For example, assume the seed of one particle results in: (+a, +b, -c)
Then the same seed should result in (-a, -b, +c) for the other particle. Also, note how we choose the orientation to detect randomly with 1/3 probability for each particle individually, so there are 3x3 = 9 possible ways of detecting each with equal probability, 1/9. I will write the detected orientations like this: [a,b] means we detect in orientation a for the first particle and orientation b for the second particle.
[a,a]: (+, -) -> DIFF
[a,b]: (+, -) -> DIFF
[a,c]: (+, +) -> SAME
[b,a]: (+, -) -> DIFF
[b,b]: (+, -) -> DIFF
[b,c]: (+,+) -> SAME
[c,a]: (-, -) -> SAME
[c,b]: (-, -) -> SAME
[c,c]: (-, +) -> DIFF
Remember how each of these had equal probability? There are 5 DIFF results but 4 SAME results. So there is a 5/9 chance that we get DIFF but only 4/9 chance we get SAME. If we run the experiment many times on lots of particles, we should see roughly 5/9 = 55.6% DIFFs. But that's not what happens...
In reality, if the two particles are detected in the same orientation, e.g. [a,a], the outcome is still DIFF (1 positive and 1 negative), BUT if they are not in the same orientation, they are more likely to be SAME than DIFF, which doesn't make sense at all. If you take a look at the list, when the detections are not in the same orientation, there should be a 50% chance of being SAME or DIFF. It's as if the other particle is trying to copy whatever this one did in the orientation it was detected in, regardless of what the "seed" tells it to say.
P.S. If you're wondering what the 50% mentioned in the video refers to, it is the overall probability of seeing SAME and DIFF in reality, including detections in the same orientation. Since all those detections are DIFFs, then the detections in different orientations have to have more SAMEs than DIFFs to get it to 50% overall, which is weird.
Why at 7:20 does he say there are only six possible outcomes instead of eight? If you include (+a,+b,+c) and (-a,-b,-c) then the 50/50 observation when measuring in DIFFERENT directions is exactly what you would expect from classical physics. (To be clear, at 6:52 he says, “Something interesting happens when the two detectors AREN’T measuring in the same direction”, which flows into the 50/50 observation.) What am I missing? Or did I just break quantum mechanics?
@@darylmartin4263 First, he didn't include those because it wouldn't make sense in classical physics for a particle to have the same sign in all 3 directions. Imagine you're moving in an unknown direction, and your movement is measured in 3 specific orientations with 120 degree intervals. How can you possibly be moving positively in all 3 orientations? There should be two positives and one negative or two negatives and one positive. We are actually measuring the spin and not the "movement", but the analogy still holds; it wouldn't make sense for it to have the same sign in all orientations.
Second, even if you include that for a total of eight outcomes, you would still see more DIFFs than SAMEs. In fact, for those particles you would only get DIFFs; one particle is always positive and its entangled pair is always negative; so we should measure it to be more than 55.4%. But no, we get 50/50 DIFF and SAME overall.
In classical physics, the 50/50 observation when measuring in different orientations is indeed what we expect, but not all detections are in different orientations. Some are in the same orientation, where we expect different signs 100% of the time. Therefore, *overall* we should get more DIFFs than SAMEs.
But in quantum physics, and in reality, we get 50/50 *overall* . So, even though we always get a DIFF when measuring in the same orientation, the measurement in different orientations is *not* 50/50. It actually is more likely for them to have the same sign.
But how the hell is this possible? And how does quantum physics try to explain it? Well, the only way we can wrap our head around it is this: When you measure one of the entangled particles in a specific orientation, it immediately forces the other to take its *exact* opposite orientation, no matter what it was doing before that. That way, when you measure the second particle in a different orientation, its "forced" orientation is only 30 degrees away from the measured orientation, so it is more likely to give SAME than DIFF.
Does that mean measuring one particle affects the other faster than the speed of light? Yes. But isn't that... spooky? Yes it is. It's "spooky action at a distance".
@@adoosth I don't get your statement "How can you possibly be moving positively in all 3 orientations"
Why is this impossible? For instance, it's possible to have all positive components of a velocity so
@@lietpi From what I understand, the detector doesn't measure spin in 3d space but a 2d plane of space. Therefore, you cannot have a positive detected for a, b, and c because each only has x and y coordinates.
This is the best explanation of Bells' thought experiment that I've ever seen, and the only one that doesn't even mention "spooky action at a distance". Congratulations!
FTL interaction is just another name for "spooky action at a distance"
Nothing spooky going on, the 'interatction' measured in QE is a point in the past. Einstein made a joke in some notes and people have been freaking out about nothing for a while now. Is it cool and interesting? Yes. Is it remotely FTL? No.
2:02 One explanation I really love for this interaction is the one that says a positron is just a time-reversed electron. What that means is that when you see the photon disappear and a electron/positron pair appear, what's actually happening is a time-reversed electron is colliding with the nucleus, it absorbs a photon (or emits one in reverse time), and then it changes direction moving forward in time as the electron we observe.
It changes an interaction between three particles, two of which are entangled, to an interaction between two particles with one of them simply reversing its direction through time, no entanglement required.
So when we measure the entangled particles, are we just measuring two 'legs' on one higher dimensional object?
@@kendrickmcelfish2805 In a sense, yeah. If we restrict the example to an electron/positron pair, you're basically measuring the same particle twice at different points in its lifetime.
Finally my favorite topic from my favorite guy on UA-cam
"We need to relax our expectations". Totally agree. It's ok by me if I don't have the Absolute Truth served for breakfast with my coffee. And maybe we need to, ontologically speaking, give a bit more weight to role of probability in constructing reality instead of just insisting that only what is actual (whatever that means nowadays) can be real.
Great! Given the complexity of the subject and the accuracy of your explanation, this video must be the best of all!
My friend, I've been waiting for this video since the causality cause and effect video😂 very excited
That's a long time!
Great vid! Would love to see a video on the delayed-choice quantum erasure experiment, as I cannot fully comprehend/understand those results. I think the key to understanding quantum mechanics is avoiding trying to visualize based on particles moving about in our 3D space, and trying to visualize as wave energy blips in a quantum field, where entangled wave energy blips are part of the same entity with instantaneous coordination in their respective quantum fields, and resolve to a particular spin (and as a particle rather than a wave) upon wave function collapse at measurement.
I covered the quantum eraser a couple years ago: ua-cam.com/video/iyN27R7UDnI/v-deo.html My pace was a little faster back then, but it should have what you're looking for.
@@ScienceAsylum Thanks for the great video that you posted. I like that you actually provide a possible solution that in theory could work, rather than just explain it away based on correlations retrieved after the experiment is completed (like some others that you can see on youtube). I do however question whether your proposed solution makes sense. I posted my comment on your other video. Here it is here:
Hmm, re your comments at 10:40 that what happens on the screen determines whether the which way path information is erased or saved -- I saw that at a possible explanation somewhere, but in theory, the experiment can be modified to allow a human to randomly allow / disallow the entangled particle to pass through the splitter/detector or bypass the splitter/detector after the other particle hits the screen (e.g., imagine the detector / beam splitter being a light year away from the rest of the experiment). So, if the particle that hits the screen communicates to the entangled particle at that moment, the human could in theory change the outcome by physically moving the splitter (or detectors) into / out of position after the other particle hits the screen. I'm not a physicist like you, so perhaps I'm missing something, but the only solution that seems to work in my head is that there is no wave function collapse at the screen when the particle hits the screen, but rather at a later time period. In that solution, what happens later can change the wave function probabilities so that when the wave function finally collapses, the particle does what it should do based on whether the which way path information is saved or erased.
What are your thoughts about what I wrote above? Also, wondering if you could make a video on wave function collapse, and should there always be wave function collapse when a particle hits a screen when its entangled pair can still be measured to determine / not determine which way path information.
Again, thanks for your great videos! They are my favorite along with Arvin Ash on youtube!
This is one of my favorite topics. This was a great explanation (the best I’ve seen), thanks for doing this. I didn’t know that a photon could become an electron / positron pair…. Cool. However, I like to think that God doesn’t play dice with the universe, so, I am wondering if some day we will figure out something we have been missing and look back and think wow, how did we miss that! :)
There are so many theories, one which is almost a joke is called "one electron universe" where everything can be made by a single electron moving backward and forward in time. 🤯
Hidden variables would allow for determinism. Bell experiments rule out local hidden variables, but do not rule out non-local hidden variables. Some sloppy descriptions of Bell's inequality fail to make this important distinction.
Taking the theological route on this question, do you think God holds us accountable for our actions? If the universe is completely deterministic, then your every thought and action could have been predicted before you were even born! Divine judgement wouldn't make any sense unless some aspect of our decision-making process is genuinely unpredictable.
@@flexico64 It’s the greatest question of all isn’t it?! Me sitting here debating whether or not to reply to this question could literally have been planned out 13.7 billion years ago! Including my hesitation to google how old the universe is. Hmmm. Kinda nuts.
1:20 LMFAOOO I needed this laugh so badly! Love you and everyone that helped produce this video!
So that means when we turn into photons we'll have eternal life? Cool message for Easter 🐇! I'm still confused about how you entangle the particles. Maybe it's a mathematical reality but not physical, as you pondered. So much more to learn! I feel like we're just starting to understand physics.
For a photon time doesn't tick at all, so all its experience is packed into a single moment. That's kind of an opposite of eternal.
@Bill Allen - "I'm still confused about how you entangle the particles"
if i remember right, the way they do it is they fire gamma rays at a solid substance... what substance i'm not sure... i think i read somewhere once that they use a certain type of crystal, because their quantum modelling had showed them that certain crystals lend themselves more to pair production than other substances, because of how the atoms are arranged (but can't remember for sure on this :p)
the gamma ray fired at the object needs to have at least 1.022 mega-electron-volts (MeV) of energy, because an electron has 0.511 MeV of rest mass energy... and since they are attempting to create an entangled electron-positron pair, (the positron also having a rest energy of 0.511 MeV), under mass-energy equivalence relation it adds up to 1.022 MeV being needed as the initial input energy on the gamma ray they are firing at the crystal or what have you
Google mentioned that the gamma ray has to approach a nucleus for the event to take place, to fulfill conservation of momentum... the nucleus receives some sort of recoil energy from the event
i could have sworn i once read somewhere that pair production can sometimes occur in the vacuum of space without any nuclei nearby, but i can't remember where i read that and i want to be careful not to spread misinformation on accident hehe... so not sure on that part :p
i believe under many circumstances the positron that gets created almost immediately annihilates itself and whatever it crashes into, because it is a form of antimatter... and when antimatter crashes into normal matter both particles often turn into a photon and radiate away
but i guess for these entanglement correlation experiments that Nick Lucid is talking about, the scientists have figured out some way to get the positron to live longer and corral it away into a slightly safer situation maybe?
i'm not sure... thats just me guessing... how they would have achieved such a feat, if this guess is correct, is itself very fascinating to me... because crystals, and all solid objects for that matter, are probably very dense... and just a giant thicket of stuff for a positron to crash into and transform into a photon... so getting a positron to survive for a longer time is probably very difficult to do lol
maybe anyway :p
I’ve always wondered about the idea of measuring one of the particles as up/down and the other as left/right so it was very cool to see that addressed.
Vsauce Back in Action, Or is it ??
I've always thought it's a bit easier to think about entanglement in a looser definition of particle. Once you have a multi-particle system, you have to describe them as one wavefunction, and so thinking of entanglement as this weird particles talking to one another faster than possible seems a bit unnatural. Instead, I like to think of it as two particles combining into one sort of 'new particle'. I'll admit that this isn't the most rigorous argument, and there are likely issues with it, but it's helped me stomach the weirdness of entanglement a bit better.
Also, I'd love to see a follow up video about how closely related entanglement is to factoring. It's a beautifully simple concept, and it gives nice intuition for why checking for entanglement is such a computationally difficult problem.
I have a pretty annoying question: how can we actually do the experiment you outlined? How do we ID and preserve entangled particles, send half of them near the moon, and do the measurements in a time-synchronized way?
A bonus: how can this be interpreted via the pilot wave interpretation?
Yes, a Chinese group separated entangled particles one in a satellite in 2020 - look it up if you want the details.
Pilot wave theory turns out to be a bit redundant of an explanation, but it predicts all the same probabilities as standard QM.
Great video sir. Very well done.
Key words in the video " lower the expectations "
Tunnel vision is a serious problem for humans..
Your humbleness is both refreshing and hopeful.
Is it possible that universe is expanding in true emptiness (where nothing exists not even space) by obeying the second law of thermodynamics (high energy flows towards less dense energy)? Because if it's possible, we don't need dark energy to cause the expansion, and it also leads to the Big rip.
This channel is amazing, i wish youtube recommended you sooner, this video is pure brain food, thank you so much! :D
You have the ability to explain such matters like no one else I know, man. I absolutely love your channel!
Regards from a quazy fan living across the hemisphere.
I just found this channel a few days ago and am slowly going through the backlog. :) As a fellow Michigander (well, Michigoose if you want to get technical), it's pretty neat to see a more-or-less local as a successful UA-camr. As for being crazy in Michigan, well, aren't we all Michugenah here? (I am also such a dork.)
I'd like to believe I turned Kyle on to your channel. He was doing a list ranking of science channels, and tragically you weren't on the list at all. I told him about your channel and he commented like he's not heard of you. A bit later you were mentioned as someone who has a video on the topic he was talking about.
I did do a quick scroll through the comments and seen a few others mention you, but I was the first.
I don't really know if he had known of your channel or not. But I am taking full responsibility. I like the idea of being the person who made this match possible. Though it likely it wasn't.
Keep doing what you're doing. You're doing it right.
Appreciate ya.
Thanks for mentioning me to him! (For whatever reason, I tend not to be included on those science educator lists. I'm used to it.)
Well, it's a wrong I hope gets soon corrected. And I think you have a bit more influence in these areas then people see.
🍴 I have my fork ready for classical physics, but the set came with a knife that I'd like to cut to the heart of quantum mechanics with and really understand what's going on.
This is one of the most beautifully thoroughly explained videos i have ever seen on this topic
I like the Multiverse explanation of entanglement the best. Every observation we make takes us instantaneously into a different universe within the Multiverse. This doesn't violate the speed of light being the universal speed limit since we can't use quantum entanglement to send matter, energy, or any form of information faster than light.
What I leaned about Quantum Mechanics today is that I have no idea how Quantum Mechanics works!
Welcome to quantum mechanics 🤓
You’ve done it… finally gave an explanation I can follow on the Bell experiment… thank you!
You're welcome! 🤓
I have struggled for a long time with the notion of Bell's Theorem. I understand that Bell's Inequalities are violated, but in my searches I have had little luck warping my brain around why it is a theorem, and why we shouldn't natural expect to see trig equations like sin^2(theta) and cos^2(theta) when dealing with the probability of a random spin angle having an up or down component in its vector in a system of hidden variables. The math just doesn't feel right, and I would like a more in depth explanation of just the math without the rest of entanglement and quantum physics involved.
Keep up the good work, I don't always agree with the interpretations of the results, but I find the experiments themselves fascinating, and I really enjoy your videos.
The smirk you gave before "Back to the timeline".....you had me there 😂😂😂
Einstein nailed it when he called this stuff " Spookiness at a distance " . Best description I've ever heard.
11:25 Could the particles still be connected in some way via of the upper dimensions predicted by string theory?
Love the expectant pause before the Conservation of Energy pronouncement we all know is coming
yay! i love these videos, been watching all of them all in and out of order by upload date. i watch them all a whole bunch but turning the playback speed way down really helps me fully understand the videos. the watching of these videos is a whole ass experience. i found slowing down the playback rate a ton on these makes for a ‘magical’ experience. ur really immersed in what the ships AI is showing u. these videos are awesome although i still have no clue if a photon is a physical wave or a wave of probability lol
most understandable explaination for bell Theorem
Thanks! 🤓
I'm glad you are here, thanks for the video!
Just found your channel! Love it, you are such a goofball, and yet a genius with your clear and simple communication
In the fabric of space where mysteries roam,
Entanglement weaves its intricate tome.
A phenomenon profound, a cosmic ballet,
Where particles dance in a quantum display.
Entangled they are, in a quantum embrace,
Bound by a bond that time cannot efface.
Though separated by vast cosmic spans,
They dance in unison, defying our plans.
But how does it break the universe, you ask?
In its enigma lies a daunting task.
For entanglement whispers of connections unseen,
A web of existence, where reality's keen.
Break one entanglement, and chaos may ensue,
A ripple effect, tearing reality askew.
For in the quantum realm, where uncertainty reigns,
Entanglement holds the key to what remains.
It challenges our notions of space and of time,
Revealing a truth that's profound and sublime.
Entanglement breaks the universe apart,
To show us the secrets at its very heart.
So ponder this mystery, this cosmic affair,
Entanglement's dance, beyond compare.
For in its embrace, the universe bends,
Revealing the wonders that time transcends.
Okay, I am really old and not a Physics master, so be kind!
It seems to me, based on this video, that the direction of the super positioning of these little suckers changes VERY quickly - seemingly instantaneously. If that is the case does measuring the direction at any one instant really mean anything? The "instant" you determine a direction it within an an instant it has changed to an unpredictable new position.
Help me to understand this!
EACH of your videos are amazing! You are a true teacher!
That's the fun of it all! If it's in a superposition state it could be spin up could be spin down who knows. BUT if I measure it to be spin up, it will stay spin up. Once the measurement is done we can deterministically say it will remain in spin up.
@@jimmypizza9854 My point is, does it really matter?
Once you measure it, it has changed state. Also, some think that measuring something influences its nature. So, once again - what is the point of measuring it! Besides, it is changing state so quickly it is _essentially_ in two states at the same instant!
Help!
Your videos make me feel like I must learn more. Thanks for that............. I think.
Excellent video! I’m a big fan of QM and your stuff always brings a new perspective and often new clarity to these topics. However, in all my reading and viewing, I’ve never experienced a good explanation for HOW entangled pairs are produced. Any chance you can make a video about how “entangled particles are produced?”
Incredibly concise explanation. Thank you ol chap.🧐