Tim Maudlin is THE GUY who takes all the pomp and circumstance off modern physics and helps ground us in remembering that despite all the "success" of our theories, literally none of them are actually "right."
But in insisting on the absolute evidence of non locality, he mystifies QM, without any conclusion how to solve the measurement problem. It's still unsolved, since ErwinSchrödinger put a cat into a box about hundred years ago. The 22noble experiments did not rule out locality and hidden variables.
@@Thomas-gk42 my point is simply that there is an almost ecclesiastic nature about modern science, and Tim succinctly shows the emperor has no clothes and we don't have all the answers. I don't even fully agree with Tim, I'm into all sorts of spooky esoteric shit that he would dismiss as "silly." It's just that he has a way of profoundly reducing the complexity of the disconnect in physics that shows there's waaay more out there to be solved.
@@Thomas-gk42Odd statement. He actually proposes interpretations that demystify QM and solve the measurement problem. How did you come to that conclusion?
Definitely one of the most rewarding and insightful episodes I've seen on TH-cam! I think anybody who has any interest in quantum entanglement should watch this!
I remember reading somewhere that Feynman said something along the lines of “there are probably less than 100 people worldwide that understand relativity at a intuitive level. And probably less than 10 that understand quantum mechanics at an intuitive level.“ That always stuck with me.
Actually he said that if you think you understand quantum behavior, you don't understand it. It's a variation of a beautiful Irish expression: "If you're not confused, you don't really understand what's going on."
Those who understand Advaita Vedanta, and there are many (more than 100), understand quantum physics, non locality at least, and so-called spooky action at a distance (a misnomer to those who understand). Same, even more so, for those who have had out of body experiences and often for those who are deep meditators or attain samadhi. Reality is non local. Time, space and distance arise as universal consciousness attenuates to the brain and senses, which makes them ultimately, though inherently, illusory. Take up Advaita, with any luck it will become clear. Advaita simply means, not two (the One appearing as separate objects to the senses).
@@iamhudsdent2759 This overlooks the serious disagreement among advanced contemplative traditions. Dzogchen is at least as serious and rigorous as Vedanta yet fundamentally rejects and deconstructs the assertions of Vedanta both on philosophical and yogic grounds. Before we make these huge leaps outside of the dicipline of dharma, if you will, we have to convincingly settle these issues within the discipline.
A really thorough explanation of basic concepts of EPR, Bell's theorem and features of quantum mechanics. Thank you and your guest for this amazing discussion.
Perfect - I've waited for this quite a time. Somebody breaking down this whole issue in a way I get to understand it. Thank you very much guys and deep gratitudes.
Man I can't tell you how much I appreciate the fact that you're willing to lean in to some bold technical confrontation for the better of perspective learning and understanding. Thank you for what you do, hope it keeps growing!
Thanks both Tims! This was an amazing exposition with a lot of historical context. I’m not a physicist but a Statistician and I found the whole discussion very illuminating, especially the tables explaining Bell’s inequality. Wonderful job!
Thanks. Finally a thorough walk through instead of the 10 minute explanation one usually finds on youtube. Thirty years ago I joined a class with the simple name "foundations". It was optional and not very popular among fellow students so we could discuss the topics (which EPR was one of) in a small group. I liked it very much and kept the syllabus and lecture notes until this day.
I have to compliment the two Tims for this interview. I think that it explains the key points in EPR and Bell's Theorem with more clarity than I have seen before.
I disagree when Maudlin says Einstein's issue was just nonlocality. If you read Einstein he was clearly also heavily critical of the nonrealism of the Copenhagen school which inherently falls out of its indeterminism. He gave a precise example using atomic decay pointing out that if you accept it is indeterministic then you cannot admit the decay ever occurs or doesn't occur until it is observed because the wave function does not describe a moment of decay. That's why Einstein asked Abraham Pais "do you really believe the moon doesn't exist when you aren't looking at it?" You cannot salvage realism by positing that the wave function is an ontic state itself either (that the atom's ontic state is not decay or not decay but the state described by the wave function) as Eugene Winger showed this still forces you to abandon realism ("Wigner's friend") that is, unless as Bell argued (in his article "Against Measurement") you also accept the collapse is ontic as well (in the sense of Penrose objective collapse). Yet if you accept objective collapse then you need a theory of measurement, i.e. it implies quantum mechanics is an incomplete theory, which was Einstein's position in the first place. Einstein's did have criticisms of nonlocality, but he was also critical of the implied nonrealism of the Copenhagen school (at least in the sense that it is commonly formulated) that forces you to abandon the existence of an objective reality independent of the observer. He was quite clear on this in his writings. Even as Maudlin points out the EPR paper never mentions nonlocality but instead a "criterion for reality" where locality is only implicitly assumed. The main point of the paper was incompatibility with realism. While you can argue correctly that the paper in fact, due to its implicit assumptions, only shows an incompatibility with _local_ realism, if you read Einstein's other writings he gives other arguments that don't depend on locality, because his main concern was realism, and ultimately locality was secondary, but still important because he thought locality is needed to make it compstible with General Relativity (he even dabbles into superdeterminism in onr paper he wrote but instead calls it "overdeterminism").
this was great. U did a great job writing down the math so I could follow along with his talking. I remain unconvinced that reality does not obay Bells inequality. The odd/even up/down meassurements failed to show me how it was broken. I have tried to understand this many times, so it's not your fault. Your video was great!
@@grumpytroll6918 When he says that the meassurements breaks Bells inequality, they just don't break Bells inequality. It is entirely plausible to get those meassurements without breaking the inequality. So I guess that was the part I didn't follow?
This was great! I'll be watching it again. Bell's theorem is difficult enough without being misled by faulty concepts/terminology -- as happens in so many videos about reality vs locality vs hidden variables. Thank you Tim Maudlin for covering it for us in this venue. Great work Timothy. Feynman went so far as to explain pilot wave theory in his lecture-based book _QED_.
Loved conclusion. Progress can be said to have been made if clear questions are raised. Additional/hidden variable theories naturally raise the question "What variables?"; Collapse theories naturally raise the question "How/why does collapse occur?"; Many Worlds theories are too obscure and you are left to asking "What question can I ask?
53:30 - And there it is - it's exactly that simple. Both particles have access to their shared state, at all times, regardless of how far apart they are. The theory IS non-local, and that's just all there is to it. This isn't something that happens "through spacetime." It's simply "a connection" that exists in some way we don't know how to explain.
Thanks for this well prepared interview. The agenda / logical "storyline" was very supporting in getting to grips with fundamental issues like determinism, non-locality etc.
2:26:20 - If we assume the perfect correlations assumptions is true (as can be experimentally verified) EPR just proves that locality implies determinism. What Bell's theorem proves is that if you assume determinism you must have non-locality. From EPR + Bell, we deduce that locality implies non-locality, so our initial assumption is false. Any theory of the world must be non-local.
@@eitanporat9892 And if statistical independence is not true? If tomorrow someone proves that nature is completely deterministic, would that nullify all the scientific progress that we have made and all the knowledge that we have gathered? Of course not. The insistance that statistical independence must be true in order for science to exist seems not justified and franky based in ideology.
I'm not really sure how this could be controversial. The classic demonstration of bell's inequality is polarized light filters. Each filter removes half of the photons based on their spin.... when there is one filter. When there are two filters, there's a relationship between the angle of the filters and how many photons go through - minimal at a 90 degree (or 270)/perpendicular alignment, maximal at a parallel or 0 degree alignment (or 180, I suppose). This, in itself, chucks relativity right out the window, but things get even more fun. If we add a third filter between the two and set it at a dissimilar angle to the prior - MORE photons get through the system, with an uncountably infinite polarizing filters/angles converging on unity. Barring other losses. The photons have to know what is going on ahead of them in the system so as to know how many get reflected off of the filters. At least... to the limits of what has been experimentally tested (I've yet to review the nobel work discussed). It should be obvious that determinism is not local. One could set up experiments consisting many light-seconds, to allow for locally random behavior to alter a polarizing filter and then try to measure changes to the system to probe at just how nonlocal it is. If the "quantum noise generator" locally is flippng my polarizing filter all over the place, then we would expect one of two absurd things to happen - either the system instantly adapts to change how many photons pass (which could be easily adapted for superluminal communication) - or ... somehow the photons of 3 light seconds ago knew what state the light filter would be in when they hit it, now.... which... can still potentially be utilized for superluminous communication (but there is a catch). Or...... maybe the phenomenon breaks down at a great enough distance... for... reasons. Regardless, relativity does not survive sunglasses.
@Aim54Delta how does that show relativity is wrong. It's also possible to retain locality if the future and past are determined at the same time but also if the development the universe is governed by fractal like relationships.
@@onesquirrel2713 I wouldn't call it ideology. Maudlin explains how lack of statistical independence makes life a LOT harder (if not impossible) for experimental science. That doesn't mean that it's false, but it would be a huge blow to science.
It's just too bad that there is no such thing as a measurement problem. There are only people who didn't read von Neumann's book from 1932 in wich he explains how measurement works. Read chapter six. ;-)
@lepidoptera9337 Personally, I think statistical independence is violated in Bell experiments, and simply that there's some sort of retrocausal process involving the detectors and detected particles. This means keeping locality, thus keeping all the equations of special and general relativity the same (since arrow of time is really only ever assumed in the first place for thermodynamics reasons, though Boltzmann argued against doing such a thing), as well as the predictions of effective field theory. Basically the only arguments I've ever heard against this are vague philosophical ones about how time traveling tobacco companies could scam people or something
@@etc4xg The statistical independence is between consecutive measurements. We have to be able to predict the outcome of the next measurement from the previous n measurements to talk about dependence. Can we? No, in general we can't. That inability to predict (lack of correlation) is what we mean by independence. What matters is that the sequence of events and their precise timing doesn't matter. Only relative event frequencies matter. That is the underlying assumption that leads to unitary, linear dynamics. It is, of course, not true that every measurement is independent. The measurements of the orbital position of a planet are not (they are, indeed, highly correlated) and that's why the formula for planetary motion is not linear. Quantum theory is the description of a very special kind of system that is NOT guaranteed. We have to test if the independence condition holds on the actual physical data. If it does not hold, then we can't apply the formalism. This is such a triviality that the introductory textbooks are not even mentioning it. Having said that, anybody who wants to be taken seriously about the foundations of quantum mechanics better know this. Most quantum mystics don't seem to know any of this, or if they do, then they are lying to the general public about it because it destroys the entire false mythology around QM.
Yes, this was a very rewarding 2h40min! So much so that I will be viewing it again and again. The one lingering question for me is why completeness is required of the theory. From whence does that come? Did I miss something? Or does this derive from some vague idea like "beauty"?
Thanks for this. Been working through Maudlin’s work and it has been a rough go. This video really helped me understand why Maudlin’s ideas haven’t caught on. It’s harder work for not a lot of effect. All the calculations become harder but I am not seeing the value from making it harder. Feynman’s ideas at least made the calculations easier with integrals, but this seems like a project that would take decades to even touch the reliability of the standard model. He could be right, but I can see why few people want to take up the task of working with it.
No, he is not even right. Neither was Feynman, by the way, but Feynman's initial formalism can be rescued and it is useful as you said. There are, however, hints that it is extremely naive and that there are better (and much shorter) ways to get to the same results. But proving that seems to require some extremely hardcore math and it may take another couple of decades before the actual mathematical picture will fully emerge.
@@lepidoptera9337 I agree he is probably not right. While his project may be useful, it also extremely hard to work with and mine good information from. Agree with Feynman. He was “right” in the way Newtonian dynamics was. A good foothold for further exploration but obviously missing some critical information. Maudlin doesn’t even have that,
@@fakename4683 What would be useful is if we would finally start teaching physics rationally in high school. Any of the things Maudlin talks nonsense about can be explained trivially at the level of high school physics. The reason why people are utterly confused about the microscopic world is entirely psychological. We are spending most of K-12 to instill a 19th century (and thus wrong) mental model about the world into kids by using the 19th century (also wrong) teaching method that uses the threat of withheld parental love as retaliation for bringing home failing grades. That is ridiculous, both on the educational and the science side.
@@lepidoptera9337 Rational is slippery subject to me. I have always been a bit of a proponent of dialetheism so I don’t know how much I think a rational study of physics would accomplish. Do agree that HS infantilizes many subjects. Biology is still stuck on Mendel for some reason.
@@fakename4683 The difference between rational and irrational is made pretty obvious in politics, with the irrational side being patently laid bare by folks like Trump and Putin. That is what "irrational" looks like: it eventually starts threatening your life. ;-)
Oh yeah Nick Herbert! I read his book about 20 years ago. I prefer Tim Maudlin's presentation here - he makes it very easy to understand yet it is fascinating.
Awesome exposition. Clarifying question - Isn't the initial assumption of entanglement - that the 2 particles are entangled from the very beginning....isn't that assumption, in itself, a hidden variable? For example, the 2 different colored socks....the fact that it was already pre-determined that they will be of different colors...that pre-determination, in itself, is a hidden variable. And that pre-determined information is carried with each sock, no matter how far apart they are. And therefore, no action at a distance is needed.
There is nothing "hidden" about entangled states. They exist because of local conservation laws. That is not a physical mechanism. It's the absence of a physical mechanics that breaks the conservation.
The evolution of scientific understanding is the evolution of our thinking and I appreciate that he never loses sight of how we think about things and is concerned about it.
I am among those who resists accepting “non-locality”. I accept that this may be my problem, and I remain open to letting go of my attachment to causality and locality. But I remain VERY suspicious that non-locality can’t really be used to transmit information as a speed higher than C. Otherwise, I stuck to EPR
I appreciate anyone thoroughly examining theorems. Those things in the ether as Helena Petrovna Blavatsky called it become increasingly theoretical and even their proof in physics becomes increasingly subjective. My intuition however guides me towards the multiverse, non determinism, non linearity, non finality and non locality. I also find it logical. We have to keep in mind that we are dealing with the Infinite.
53:48 There is spooky action at a distance only if you think of the states of the two particles to be to be independent of each other, whereas in reality they are really described by a single state which entangles the two particles, so that when a measurement is made on any one of them, it collapses the entire entangled state to one of its components, or if you are uncomfortable about collapses then you can always assume that in different universes the outcome is different, as in the many worlds interpretation. Or if you are uncomfortable about many worlds, you can assume the quantum block universe where the wave function of the universe is a unique wave function which has been existing forever and all outcomes of all experiments are all predetermined. At any rate when the particles start off there is no way of knowing what momentum the particles carry because this lies at the heart of quantum mechanics. It's always the case that there is a certain probability amplitude associated with each particular momentum. So it's not a case of Bertleman's socks. 56:53 Any residual indeterminism destroys the perfect correlation? No it doesn't, the states at the beginning are a linear superposition of all possible zero momentum two particle states and in this sense the momenta are perfectly undetermined and yet perfectly correlated since each component of the entangled state is a zero momentum state in which the two particles have opposite momenta. 58:17 There is indeed a unique state in both cases and that's it is a linear superposition of all possible zero momentum two particle states. At this point I believe I have to stop listening to the lecture anymore.
Your first point formulates entanglement in a way that overlooks what the spooky action at a distance issue is in the first place. For instance, you use the phrase "collapses the entire entangled state" without taking into consideration that this collapse, naively formulated, leaves unanswered how such a mechanism can be accomplished across arbitrary (spacelike separated) distances in the first place. In other words, you smuggled spooky action at a distance into the collapse. Your second point misunderstands the use of indeterminism in this context. All that is being said here is that if there is indeterminism to Alice's measurement after Bob does a measurement, then there can't be a perfect correlation, because a perfect correlation requires a uniquely specified outcome (the opposite of Bob's measurement). There is no controversy here. Your third point also misunderstands the discussion about determinism. I would encourage you to revisit these topics (and/or the video) with a greater appreciation of the complexities and subtleties of the issues involved.
@@TimothyNguyen It can be accomplished across arbitrary space like separated distances because the real space in which all this plays out is a multi particle Fock space in which the wave-function appears as \int d^3p (psi(p,-p)+psi(-p,p))(phi(p)phi(-p))|0> where the psi's are wave-functions while the phi's are creation operators of the scalar field. For fermionic fields there would be a change of the superposing sign. When a collapse takes place, either of the two components get chosen, when psi(p,-p) gets chosen, the first particle gets assigned momentum p and the second one -p, and similarly for the second component. Since the position space label doesn't even make an appearance, it follows that that this would happen irrespective of where the particles are, or how far they are separated. Your rebuttal of the second point makes no sense. What do you mean by the statement, if there is indeterminism to Alice's measurement after Bob does his measurement, by the standard understanding, there can never be any indeterminism to Alice's measurement when Bob does his measurement, they are always perfectly correlated. What I am trying to say is the results of the measurements are completely undetermined beforehand since the particles are in a linear superposition of all possible momentum outcomes besides being in the linear superposition shown above, and the latter allows them to be perfectly correlated to each other as well. Regarding the third point I believe what I have said is absolutely clear. Trouble with Maudlin is the standard trouble with philosophers, they don't appreciate the physics well enough to make sufficiently well-informed statements.
@@TimothyNguyen There is no such thing as collapse in quantum mechanics. That meme has to disappear from the discussion. It causes nothing but consistently wrong mental models of reality. The entire idea that one measurement takes place before the other is also just intellectual nonsense. That order of events only exists for a limited class of observers. It is preferred by the observer in the center of mass system, of course. A relativistic outside observer, however, can correctly claim that it's not A before B but B before A. That claim can, of course, not change the outcome, hence there can be no causal link between the two measurements, unless we are willing to throw relativity out at once.
Conservation of Spatial Curvature: Both Matter and Energy described as "Quanta" of Spatial Curvature. (A string is revealed to be a twisted cord when viewed up close.) Is there an alternative interpretation of "Asymptotic Freedom"? What if Quarks are actually made up of twisted tubes which become physically entangled with two other twisted tubes to produce a proton? Instead of the Strong Force being mediated by the constant exchange of gluons, it would be mediated by the physical entanglement of these twisted tubes. When only two twisted tubules are entangled, a meson is produced which is unstable and rapidly unwinds (decays) into something else. A proton would be analogous to three twisted rubber bands becoming entangled and the "Quarks" would be the places where the tubes are tangled together. The behavior would be the same as rubber balls (representing the Quarks) connected with twisted rubber bands being separated from each other or placed closer together producing the exact same phenomenon as "Asymptotic Freedom" in protons and neutrons. The force would become greater as the balls are separated, but the force would become less if the balls were placed closer together. Therefore, the gluon is a synthetic particle (zero mass, zero charge) invented to explain the Strong Force. An artificial Christmas tree can hold the ornaments in place, but it is not a real tree. String Theory was not a waste of time, because Geometry is the key to Math and Physics. However, can we describe Standard Model interactions using only one extra spatial dimension? What did some of the old clockmakers use to store the energy to power the clock? Was it a string or was it a spring? What if we describe subatomic particles as spatial curvature, instead of trying to describe General Relativity as being mediated by particles? Fixing the Standard Model with more particles is like trying to mend a torn fishing net with small rubber balls, instead of a piece of twisted twine. Quantum Entangled Twisted Tubules: “We are all agreed that your theory is crazy. The question which divides us is whether it is crazy enough to have a chance of being correct.” Neils Bohr (lecture on a theory of elementary particles given by Wolfgang Pauli in New York, c. 1957-8, in Scientific American vol. 199, no. 3, 1958) The following is meant to be a generalized framework for an extension of Kaluza-Klein Theory. Does it agree with some aspects of the “Twistor Theory” of Roger Penrose, and the work of Eric Weinstein on “Geometric Unity”, and the work of Dr. Lisa Randall on the possibility of one extra spatial dimension? During the early history of mankind, the twisting of fibers was used to produce thread, and this thread was used to produce fabrics. The twist of the thread is locked up within these fabrics. Is matter made up of twisted 3D-4D structures which store spatial curvature that we describe as “particles"? Are the twist cycles the "quanta" of Quantum Mechanics? When we draw a sine wave on a blackboard, we are representing spatial curvature. Does a photon transfer spatial curvature from one location to another? Wrap a piece of wire around a pencil and it can produce a 3D coil of wire, much like a spring. When viewed from the side it can look like a two-dimensional sine wave. You could coil the wire with either a right-hand twist, or with a left-hand twist. Could Planck's Constant be proportional to the twist cycles. A photon with a higher frequency has more energy. ( E=hf, More spatial curvature as the frequency increases = more Energy ). What if Quark/Gluons are actually made up of these twisted tubes which become entangled with other tubes to produce quarks where the tubes are entangled? (In the same way twisted electrical extension cords can become entangled.) Therefore, the gluons are a part of the quarks. Quarks cannot exist without gluons, and vice-versa. Mesons are made up of two entangled tubes (Quarks/Gluons), while protons and neutrons would be made up of three entangled tubes. (Quarks/Gluons) The "Color Charge" would be related to the XYZ coordinates (orientation) of entanglement. "Asymptotic Freedom", and "flux tubes" are logically based on this concept. The Dirac “belt trick” also reveals the concept of twist in the ½ spin of subatomic particles. If each twist cycle is proportional to h, we have identified the source of Quantum Mechanics as a consequence twist cycle geometry. Modern physicists say the Strong Force is mediated by a constant exchange of Gluons. The diagrams produced by some modern physicists actually represent the Strong Force like a spring connecting the two quarks. Asymptotic Freedom acts like real springs. Their drawing is actually more correct than their theory and matches perfectly to what I am saying in this model. You cannot separate the Gluons from the Quarks because they are a part of the same thing. The Quarks are the places where the Gluons are entangled with each other. Neutrinos would be made up of a twisted torus (like a twisted donut) within this model. The twist in the torus can either be Right-Hand or Left-Hand. Some twisted donuts can be larger than others, which can produce three different types of neutrinos. If a twisted tube winds up on one end and unwinds on the other end as it moves through space, this would help explain the “spin” of normal particles, and perhaps also the “Higgs Field”. However, if the end of the twisted tube joins to the other end of the twisted tube forming a twisted torus (neutrino), would this help explain “Parity Symmetry” violation in Beta Decay? Could the conversion of twist cycles to writhe cycles through the process of supercoiling help explain “neutrino oscillations”? Spatial curvature (mass) would be conserved, but the structure could change. ===================== Gravity is a result of a very small curvature imbalance within atoms. (This is why the force of gravity is so small.) Instead of attempting to explain matter as "particles", this concept attempts to explain matter more in the manner of our current understanding of the space-time curvature of gravity. If an electron has qualities of both a particle and a wave, it cannot be either one. It must be something else. Therefore, a "particle" is actually a structure which stores spatial curvature. Can an electron-positron pair (which are made up of opposite directions of twist) annihilate each other by unwinding into each other producing Gamma Ray photons? Does an electron travel through space like a threaded nut traveling down a threaded rod, with each twist cycle proportional to Planck’s Constant? Does it wind up on one end, while unwinding on the other end? Is this related to the Higgs field? Does this help explain the strange ½ spin of many subatomic particles? Does the 720 degree rotation of a 1/2 spin particle require at least one extra dimension? Alpha decay occurs when the two protons and two neutrons (which are bound together by entangled tubes), become un-entangled from the rest of the nucleons . Beta decay occurs when the tube of a down quark/gluon in a neutron becomes overtwisted and breaks producing a twisted torus (neutrino) and an up quark, and the ejected electron. The production of the torus may help explain the “Symmetry Violation” in Beta Decay, because one end of the broken tube section is connected to the other end of the tube produced, like a snake eating its tail. The phenomenon of Supercoiling involving twist and writhe cycles may reveal how overtwisted quarks can produce these new particles. The conversion of twists into writhes, and vice-versa, is an interesting process, which is also found in DNA molecules. Could the production of multiple writhe cycles help explain the three generations of quarks and neutrinos? If the twist cycles increase, the writhe cycles would also have a tendency to increase. Gamma photons are produced when a tube unwinds producing electromagnetic waves. ( Mass=1/Length ) The “Electric Charge” of electrons or positrons would be the result of one twist cycle being displayed at the 3D-4D surface interface of the particle. The physical entanglement of twisted tubes in quarks within protons and neutrons and mesons displays an overall external surface charge of an integer number. Because the neutrinos do not have open tube ends, (They are a twisted torus.) they have no overall electric charge. Within this model a black hole could represent a quantum of gravity, because it is one cycle of spatial gravitational curvature. Therefore, instead of a graviton being a subatomic particle it could be considered to be a black hole. The overall gravitational attraction would be caused by a very tiny curvature imbalance within atoms. In this model Alpha equals the compactification ratio within the twistor cone, which is approximately 1/137. 1= Hypertubule diameter at 4D interface 137= Cone’s larger end diameter at 3D interface where the photons are absorbed or emitted. The 4D twisted Hypertubule gets longer or shorter as twisting or untwisting occurs. (720 degrees per twist cycle.) How many neutrinos are left over from the Big Bang? They have a small mass, but they could be very large in number. Could this help explain Dark Matter? Why did Paul Dirac use the twist in a belt to help explain particle spin? Is Dirac’s belt trick related to this model? Is the “Quantum” unit based on twist cycles? I started out imagining a subatomic Einstein-Rosen Bridge whose internal surface is twisted with either a Right-Hand twist, or a Left-Hand twist producing a twisted 3D/4D membrane. This topological Soliton model grew out of that simple idea. I was also trying to imagine a way to stuff the curvature of a 3 D sine wave into subatomic particles. .----------------------
Part of my job involved running a 6 session anxiety management course. At the last session (consolidation and feedback) I asked if there were any last questions. A man who had attended every session said .. “See that anxiety .. what do you do about that?” Now I know how he felt. 😊 He eventually overcame it BTW. Being serious .. I was tired and fell asleep 💤 with Bertlmann’s disembodied socks 🧦 meandering through my consciousness. Will watch again. 😀
Does anyone know why in the GHZ thought experiment, when all three take measurements in the X direction it has to be odd? I cant follow the argument because I dont know why this has to be true
Interview Professor Jean Bricmont on Bell's Theorem also! Tim has hosted Professor Bricmont at NYU!! Bricmont points out that even Stephen Hawking did not understand Bell's Inequality nonlocality. Very fascinating indeed. Professor Basil J. Hiley, the collaborator of Bohm, also emphasizes how most physicists do not understand nonlocality.
Firstly great job to both Tim and the host for clearly articulating the key ideas. I do however disagree with Tim’s dismissal 2:29:40 that “there is nothing that would count in a proper sense with a theory that you call QM.” To understand Quantum Mechanics the key conceptual paradigm shift that one needs (and Tim refuses to accept) is that particle properties don’t have any reality until they are measured. The host tries to raise this point from 2:22:40 to which Tim essentially dismisses the question on the grounds that EPR proved that the local theory must be Determined. Whether intentionally or unintentionally Tim conflates“reality” with Determinism, and unfortunately out of politeness or more likely out of being unable to follow Tim’s train of thoughts, the host doesn’t confront him on it. Let’s break some things down. EPR don’t prove anything. They certainly don’t claim to prove that locality plus spooky action at a distance implies determinism. And in my opinion they don’t even prove their actual claim that the wavefunction is incomplete. EPR define reality as being able to predict the outcome of a property with 100% accuracy without disturbing it. They then show that it’s possible via entangled pairs of particles to either determine the momentum of an entangled partner without disturbing it or the position of an entangled partner without disturbing it and so they conclude both realities must exist. They then claim that because the Heisenberg uncertainty principle (a consequence of the theory of quantum mechanics) cannot simultaneously give definite values for both the position and momentum of a particle quantum mechanics must be incomplete. The problem is the EPR argument deals with counterfactuals. There is only one entangled pair so P and Q cannot be known simultaneously. If one knows the position with 100% accuracy the fact that one “could” have measured the momentum doesn’t make it 100% predictable (for the same experimental run) and therefore, using EPRs own definition of reality, the correct conclusion is that P isn’t real. Indeed, QM/Heisenberg ensures the momentum isn’t known with 100% certainty. So the EPR conclusion (that the wave function is incomplete) is derived from a logical fallacy. EPR themselves seem aware of this and by their own admission state “indeed we would not arrive at this conclusion if we had insisted that two or more physical quantities can be regarded as simultaneous elements of reality only when they can be measured simultaneously.” This is stated in spite of the fact that their own definition of reality doesn’t strictly cover this edge case. If however we enlarge their definition so that all things that hypothetically could be known with 100% certainty about a system without disturbing it must be real then it leads to some weird conclusions about “reality” - for example we can ask the question via POVM is the particle at position x1 or not. So the partner has a reality of being here at x1. But we could equally have asked if the particle was at x2. So by this definition the partner also has a “reality” of being at x2, indeed it has a reality of being everywhere. It is well known that arguing about counterfactuals leads to apparent paradox’s in QM even within QM setups that don’t involve Einstein’s “reality” feature (see Hardy’s paradox). However QM is clear, only what you measure can be a fact. You cannot speak of any reality of things that haven’t been measured. Or as Peres’ put it “unperformed experiments have no results.” What has always surprised me about the EPR paper is that Einstein uses the QM formalism namely the EPR state as a tool to make claims about reality, and at the same time uses the formalism via the Heisenberg uncertainty principle to argue that the formalism is incomplete. But if it were true he would not only have proven a fact about reality and QM( namely that QM doesn’t describe reality completely), he would also have proven that QM itself was inconsistent with itself. This is clearly silly and why Einstein didn’t realise it I cannot fathom. EPR never made any claims about determinism. So surprised was I to hear this claim that I went back to the paper and reread it again to confirm I hadn’t missed anything. Bell has taken quite a liberty it seems to attribute this to EPR. While Tim explains this is a natural inference of EPR, all he really shows is that knowing the state of one particle in an entangled pair “determines” the state of another if it is measured in the same basis. There’s really no link to the EPR paper, except the use of entangled pairs and even that predates EPR going back to Schrödinger. I personally think Determinism is a confusing word to use because it suggests that everything is deterministic when really the only thing that is meant is that the correlations are 100%, and therefore they must be mutually determined by something. Well call it Determinism if you like but Bell is definitely assuming that there is at least one variable that is real, in the sense that it always has a value and follows some deterministic causal dynamics (essentially a classical particle property) and what he shows is that such an additional variable cannot explain quantum correlations. Now you can either take this as very strong evidence to give up on an underlying reality, and accept QM as it is (the particles were determined to be 100% correlated upon being measured because they were in a state that was quantum correlated), or you can dig your heels in and say “No! there must be these real determining variables but they move around instantaneously finding their partners and telling them what to do and btw they do so without signalling faster than light.” Not only is the theory of non-local hidden variables more uglier and complicated than QM but after nearly 100 years of trying (yes de Broglie wrote the first pilot wave theory in his thesis in 1924), nobody has been able to make it work. While Bohm could explain single particle spatial interference problems like the double split experiment they still can’t explain well spin or even entangled particles (the very subject of this video) and let’s not even mention quantum field theory. Quantum mechanics explains all these things easily. You just have to get over your hang up on underlying reality. The wave function isn’t real (there’s no non-local physical collapse). The wave function encodes the probability of possible outcomes. When you make a measurement you learn something about the world, but the possibilities are highly constrained such that once you learn this, many other parts of the jigsaw are automatically then forced on you. QM is simple, elegant, and profound but you need to shift out of the classical paradigm to make sense of it.
Thanks, that was great! I have a small question about the experimental setup. Suppose Alice's lab is on the North Pole and Bob's lab is on the Equator, how would they have to place their coordinates system to observe the perfect anti-correlations? For example, if we take the spin property and Alice makes a measurement with the magnetic field along the z direction, what would be the "z direction" for Bob?
That depends on the parallel transport from one place to the other. A tunnel will give different results than mirrors, which will give different results than glass fiber would.
Thanks so much Dr Tim and professor Tim Maudlin. So in-depth. Thanks Dr Nguyen, without your explanation, i wouldn't have fully understood the core concepts.
Given all that, it is perfectly plausible to imagine superluminal interactions that are never the less local onnthe same footing as other interactions, butbby a superluminal definition of locality, in that case and applying to bell, the action at a distance is only spooky if the effect persist for the truely simultaneous measurments, and so either you measure all the definitions of simultaneous measurements and find the inequality still breaks or you find some deviation with no proper inequality breaking at exactly infinite speed interactions. This means that for superluminal action at a distance you either get a positive result which breaks lorentz symmetry or you don't, and if you don't for one definition of simultaneous events you still have infinite other definitions to test at the same point in space for a given time, so it cannot ever be fully ruled out that these effects vreak lorentz symmetry. Which leads to the conclusion that you cannot ever fully rule out locality.
A huge point that gets glossed over often is...isn't it true that since the two entangled wave/particles are separated in spacetime they have no set causal order, thus no causal relationship? Correlations that aren't causal, so fundamentally neither outcome causes the other. Also, if the outcome is set when they are entangled, you can argue that's local since they are local to each other at that moment of entanglement.
I think your last sentence is correct, with a slight modification -- IF the outcomes were set when they are entangled, that would indeed be a locally created correlation. And I think that what Bell's Theorem shows is that nature is NOT local in the sense that the outcomes CANNOT be set when they are entangled.
What I would say is that it APPEARS that's what Bell's theorem says. But I think there is a nuance that's not part of the considerations. And that is that neither wave/particle has a set outcome until they are entangled, so they share a probability that resolves together at the point of entanglement, but that's done by quantum walking all possible outcomes and both identifying the exact circumstances by which each will resolve. So that information allows them to immediately decide how they will resolve in what we call the future. This is from the birdseye a non-evolving quantum system, almost like a frozen unit of time. It's deterministic but fully derived from probability, so it doesn't function like a hidden variable. It's local but has non-local elements, because the context for the joint resolutions must be characterized as future-looking. But if all systems are behaving identically, that determined context is explained, because all systems are doing the same deterministic walks. And with that one stroke, you suddenly have a quantum block similar to the block relativity suggests. From inside each system, they are perceived to transition from unresolved to resolved, with outside systems always having already resolved so there's always a firm background against which to resolve. But the viewpoint inside a system is just skewed, as all systems timelessly resolve at the point of entanglement. @@rfyl
Take time travel for example, unrelated to bell kind of. If you consider instantaneous travel between points, you have to travel along a surface of simultaneity, meaning what points in the spacetime you can reach instantly is dependent on coordinates, if you ask about what happens for worm holes or instantaneous/superluminal travel from a single point of view aka frame of reference aka coordinate system, it is obvious that no time travel is possible. To get time travel you need to be using different coordinate systems for travel in one direction vs the other, and so you can zig zag backwards in time along the surfaces of simultaneity. The confusion is that when you are talking about different coordinate systems for subluminal travel it is fine to consider parts of the problem from different points of view you will get the same results, but if consider superluminal travel that isn't the case anymore, and so we should stop confusing ourselves with it. To properly consider superluminal travel you need a foliation, then you can only zig zag towards the future, if you take the results from one point of view and consider the return trajectory from a different point of view you simply rotate both previously overlapping instantaneous trajectories in such a way as to male them still overlap but now representing a finite velocity, one way is a space like vector and the other way is the opposite space like vector, by changing perspectives for both you always end up with overlapping trajectories, if you then consider rotating one of them without rotating the other you are nlw changing the local space time events traveled through and arrived as, which is CHANGE in the causal structure! This is not what coordinate transformations are supposed to do, the superluminal grandfather paradox is a consequence of breaking causality by design, not by changing causality with applying laws of physics.
If position is a quantum property, how does it make sense to say Alice has one particle and Bob the other. Doesn't that mean until there is a measurement both particles are at each of Alice and Bob's labs?
Position is not a quantum property. Position is a property of the classical detector system. The only quantum properties are energy, momentum, angular momentum and charges. A and B are events where field energy is being absorbed by a detector. Before those absorption processes happen, there are no events A and B.
@@CrowMagnum There are not even particles here. What we are detecting in quantum mechanics is (field) energy. Energy is a system property. It's not a thing. One can't put a label on it. One can technically entangle e.g. the spins of an electron-positron pair, but the angular momentum property doesn't know anything about the charge property. These are completely independent quantum numbers. Think of all these properties as the (orthogonal) basis vectors of a coordinate system. We pick two random vectors and entanglement makes sure that the two vectors add up to zero. No matter where these two vectors are pointing, the sum still stays zero. We propagate these two vectors through physical space without turning them... the sum of the two vectors at the other end is still zero. There is really not much magic here.
@Tim Maudlin. Could you tell me if the EPRB experiment has ever been done without the use of magnets or other devices, only the particles and the screens? And if yes, what the results were? Thank you.
I don't know what that means. These experiments are about the consequences of entanglement on measurements that are not in the same place and/or at the same time. Measurement in physics is always done "with devices". That's the definition of "measurement".
What am I not getting. So if Anne used -60 deg and Bob uses +60 deg, are the filters not really just 60 deg apart from each other… so cos(60)^2 is 25% anti correlation which to me sounds possible to achieve
Please interview Physics Professor Basil J. Hiley! He was the collaborator of David Bohm and his focus on noncommutative nonlocality is the key truth to reality (it's also the truth of nonwestern philosophy as mind-body transformation as Eddie Oshins realized when he coined "quantum psychology" working at SLAC).
I'm listening to this and my intuition is telling me that 'spooky action at a distance' is the same particle - it is vibrating in 4 dimensions (3 Space and 1 Time). It's the vibration in Time (both +/- or forward/ back) that makes the observation not obvious. When we observe 'two' entangled particles, we are seeing one end of the particle with different 3D Space coordinates to the other end of this vibrating particle, but both ends are observed at the same 1D Time coordinate. The whole 'action at a distance' makes sense with 4D vibrations. Which means the Wave Function is incomplete. When we measure the above entangled particle, the Arrow of Time becomes significant in one Time direction with the collapse of the Wave Function. When one end of the particle provides a particular observation, the other end cannot be observed with the same property - like a pivoting mechanism on a 'see-saw'; up and down, positive and negative, north and south, spin up and spin down and on on. Information doesn't need to travel distance faster than sped of light because this isn't happening when we observe the same particle with the same Time coordinate but different Space coordinates. The Wave Function being incomplete needs to be modified to account for the above. It's like our observations and explanations are missing 1 dimension...
Not saying this is you, but it's amazing how many people spontaneously solve the contradictions in quantum mechanics after watching a few TH-cam videos on the subject. I couldn't help but wonder what you mean by the "other end" of a particle?
@@mylittleelectron6606 - Well, you never know who is leaving these comments. Personally, I studied Quantum Mechanics as an undergraduate over 30 years ago - so this isn't some first TH-cam video for me. To answer your question: The 'other end' of the single vibrating particle in 4D is the 'second' entangled particle being observed. Hope that makes sense.
@@mylittleelectron6606 It's still fun. Nothing wrong with entertaining amateur theories so long as we don't discard what professionals do. This theory was great. A really cool idea actually. Still coming up with the ideas is the easy part, proving them is another story.
@@definitelynotcole Hey, I'm glad you enjoyed it! That was one half, the other half completes the cycle at the opposite extreme: Consider taking the above entangled particle such that it approaches a black hole. The so-called Arrow of Time is broken as the entangled particle gets closer to its centre, where the 4D vibrations start to become more significant again in the Time dimension. The see-saw mechanism avoids the singularity at the centre of this black hole where the Time coordinate is so dominant that vibrations in the other 3D Space dimensions don't have a chance to form a singularity - the entangled particle appears in another Time. And so the cycle continues... You can create a thought experiment with a double-slit experiment at these extreme systems where the scattering pattern occurs in 4D such that elements of the observed pattern occur in both the past AND future, predicted by the Wave Function modified to operate in 4D...
also, just to make it a bit simple, the only requirement where neumann is right about what you mentioned, is about nodes with respect to amplitudes, any addition variable state described statistically by wave function must also never admit an outcome where the probability density is 0. that is is, the rest can be mucked around with by producing many different "micro quantum states" with specific outcomes, as long as the resulting distribution comes out right. and if you think about it, this is obvious, it is a property of all statistical physics, such as restrictions on energy for example, take a double pendulum in a superposition of classical initial conditions, none of them will evolve into a state where the energy has magically increased permanently, so with respect to the micro state phase space and the statistical description we have some node in phase space, where the probability density is 0, the dynamics are completely different but the principle is the same, none of the individual states of the pendulums involved in the evolving distribution can ever attain a larger energy than the initial value, that is a prerequisite, these kinds of constraints are all the constraints that is on producing a consistent statistical theory in general, apart from questions of special locality and so on.
I do not get it. What is wrong with the correlation being preset from the origin, like Bertelman's socks? It seems that QM just says nothing is predetermined until it happens. So why then do people think QM says that, and Bertelman rules?
I think there are two separate questions here but for correlations being always present there is a theory that holds that, it is called superdeterminism
A wavefunction says all its composite states are possible, but if they're not via correlation, then there's information the wavefunction is leaving out. The wavefunction alone cannot account for correlations, and the context is if there's more to the reality that quantum mechanics needs to address to be "complete".
Your statement sounds contradictory. Usually when people say "the correlation exists from the origin" they mean precisely that all the outcomes are predetermined. That is, there is something about the state of the system that tells you exactly what all the outcomes would be such that the required correlations are satisfied. It turns out that this is mathematically impossible for correlations as strong as those predicted by QM. In what sense do you think the correlations could "exist" before the measurement if the outcome is not predetermined? That is how are the correlations encoded in a physical system without determining the outcome?
@@Anytus2007 When a measurement is made, some sort of communication needs to pass between the two entities at the spatially separated detectors. This communication has the nature of a one-time pad rather than a real message. I suggest that there is a natural Vernam cipher at work. I can think of two different types of VC.
This is what I don't get about quantum computers. They say they use entangled qubits to do the calculations. But when the state is read, entanglement is destroyed. But how do they set the state in the first place without destroying the entanglement because now they know the state. And about those corrections that has to be done because quantum computers result in wildly wrong results (or multiple results which one might be the right one). If you already know how to correct the outcome, don't you know the outcome itself thus making quantum entanglement impossible, since you know the state already. And then, how can the qubits be in high correlated state and the result be gazillion different probabilities if there is high correlation - exactly like the video explained deterministic v indeterministic problem leading to spooky actions. I'm puzzled in so many ways not even qubit can comprehend it.
Tim this is a great episode. I've replayed parts of it. I still am not clear on the equality. Could you explain the cos formula (disagreement rate). Is this a quantum mechanical formula? Or observed experimentally? Or is it just non-quantum math? Thanks if you get a chance to explain.
QM implies the spin-correlation between Alice and Bob is -cos alpha (see Bell's original paper). If the disagreement rate (p_disagreement) is r, then the spin correlation is 1 * p_agreement + (-1) * p_disagreement = 1 * (1 - r) + (-1) * r = 1 - 2r. Hence -cos alpha = 1 - 2r. The next step in the insert at 1:44:17 is trigonometry. I realize now the whiteboard uses alpha but the insert uses alpha/2. Oh well, the lowest insert indicated that we messed up factors of 2 during the live presentation so the reader is meant to know that they need to be inserted appropriately.
Given the example of a box of gas, reminds me of an assertion that was made regarding zero point energy systems. The energy contained in the space within a teacup is enough to boil off all the oceans on Earth. As far as I know, there is no criteria for the reality of how a zero point energy system works, but we know that there is potential for such a system to exist.
There is no such thing as "zero point energy" or "vacuum energy". That concept originates from a naive quantization of the physical vacuum. It's simply math gone bad.
I agree with what Tim is saying, i know very diplomatic and economical, two compliments in one, maybe complimentarity isn't so bad after all. What i would like to hear from him is the difference between locality as in a causal structure woth a finite speed limit, and more general definitions where there is no upper speed limit. The difference matters a lot for the argument when it comes to what experiements have to be done.
The "hype" is that we made an enormous amount of progress in understanding the solution theory of Einstein's equations and the consequences they have at the thermodynamic level. It's an enormous amount of non-trivial mathematical work (and not just by Hawking but by a cast of hundreds, if not thousands).
"What Bell saw was that from their premises EPR provide a perfectly good argument...if you accept the locality assumption that's implicit in EPR you have to accept their conclusion; which is that quantum mechanics is incomplete."
Through out my life I was told Bell proved Einstein's hidden variable theory wrong and proved Bohr was right, how wrong could you get, both were wrong and Bell showed the universe was non-local.
Did you see that bullshit on the internet or are you just playing a game of telephone? At most it was said that the world is not locally real, but that does not mean non-local. That all physics is perfectly local follows directly from special relativity. If the world wasn't local, then your iPhone would have an ansible built in, but on the downside the universe wouldn't even exist. ;-)
Neither Bell nor anyone else has shown that. Tim Maudlin is a crank who's become notorious for pushing that quantum foundations illiterate falsehood (and one or two others). There's an excellent refutation of it by Werner in J. Phys. A. DOI 10.1088/1751-8113/47/42/424011
Point being, if you allow for faster than light interactions you can infact still have a local and deterministic theory. Without being conspiratorial, and without contradicting experimental results. The thing is that quantum mechanics would predict that even for all definitions of simultaneous measurements you would see the same violation, that however has not been tested, and cannot be tested in such a way to confirm the quantum mechanical prediction fully, you can only contradict quantum mechanics for a finite experiment, that means that if you wanted to rule out the violation of quantum mechanics, you would need to do an impossible experiment, only the lorentz symmetry violating result can be attained in a viable experimental setup. The null result for the violation of quantum mechanical predictions, or more generally the same violation of bell for all definitions of simultaneous measurements, is sort of a passive result that you cannot ever fully test, because there is an infinite number of simultaneous measurements you would have to do, to rule out the lorentz symmetry breaking result fully.
Also note that even if Bob can know the momentum of Alice's particle as soon as he makes his measurement, ALICE CAN'T. She still has to use the superposition of possible momentum values for her own work. That cannot change until there has been time for information to arrive from Bob.
Why not call the “hidden variable” an omitted variable? That’s what we call it in statistics when a variable isn’t included in a model but it could have some sort of bias that is unknown and not accounted for.
Why not call Santa Claus "bearded redling"? Would renaming make Santa any more real? ;-) There are no hidden variables and it's intuitively extremely easy to see why there can't be any.
@ I literally just suggested to call them something that does not mean hidden. Omitted means left out in this context, which is exactly what the content of this video suggests. It’s so “intuitively extremely easy” to see that.
I didn't get how 30 degrees equates to 25% disagreement(or 60 degrees or whatever it was supposed to be) That would imply 100% was 120 degrees(or 240), it doesn't seem to fit with the reality of the spin test.
It seems to me QED is fairly easily understood if we consider photons to be solitons in the EM field. The situation with QCD is much more complex but it wouldn't surprise me if solitons were also lurking in there somewhere.
Making rational statements, making well-founded statements starting from a given context, is very difficult. Luckily, Mr. Maudlin got to a position and rank in analysing discourse and in being acknowledged where he can make radical statements about the current state of scientific knowledge.
@@eddymoretti3742 Physics is not a he-said-she-said, kid. YOU have to understand NATURE. Which you don't. Now let me give you some more attention until your Mom comes home and feeds you dinner. ;-)
There’s more than one way to travel faster than light. We can have an oscillation in one of the ways which leads to destructive interference, and tachyonic Brownian motion in the other way which leads to broken symmetries between detectors. The entity I have described is definitely both a wave and a particle. Whether it is the same as the typical entity found in quantum mechanics remains to be seen, but the claim that nobody understands quantum mechanics could actually be wrong. The catch is that any computer simulation of the collapse of the wave function based upon this idea may need to model many dimensions of configuration space, or in other words may need to run in exponential time.
I disagree with Tim Maudlin here. I don't see any way the world can be nonlocal based on our current understanding of it. We have modern physics with its effective field theories, specifically quantum field theory which is eminently local. It's Lorentz covariant, by construction. Traditional quantum mechanics itself is not AS local because it's non-relativistic, but it's still more local than people realise. In fact, the only really ''nonlocal'' aspect of traditional quantum theory is the collapse of the wavefunction, but the vast majority of people in the field don't think that is something that actually occurs. Even Bell's Theorem doesn't necessarily imply nonlocality, as long as you don't think there is a wavefunction collapse happening. I mean, if you look at some of these so-called interpretations of quantum mechanics (including the Bohmian one Maudlin seems to be fond of), a lot of them start from the non-relativistic domain and then try to build a story from there, which in my eyes is just not the way to go. In my opinion, we ought to start from what our most well-established theories, such as QFT, tell us and then try to paint a metaphysical picture of the world if we can, not vice versa.
QFT is cheap. “Local” means that objects can be influenced only by their surroundings and that any influence cannot travel faster than light. The question/topic is not as you pose it "I don't see any way the world can be not local". It's not important whether you can see a way the world is not local. Everyone can see a way, they just need to fantasise a bit. The question is not whether we CAN see a way, but is this: DOES anything happen at the microscopic scale which shows that IT IS TRUE that---- objects can be influenced by outside of their surroundings, or (does anything show IT IS TRUE that) influences DO travel faster than light? That is the question. The answer was No in 1920, it was still No in 1950, still no in 2000, still no today in 2024. Nothing that happens at the quantum scale, nothing we have EVER observed to happen, SHOWS those things are in fact true. It's that simple. As for QFT--- yes, cheap. We are waiting for an actual theory that explains the phenomena we observe at this scale. Including Heisenberg's Uncertainty Principle (which can be regarded as driving all these phenomena into existence). We are waiting for an explanation. A theory. You know, physics? That's what physics involves -- Explaining (and describing) phenomena we observe in our world. Just like--- we were waiting for someone to explain the motions of bodies in deep space (thank you Einstein, for spending 10 years of your life, to nail that down, where nobody (prior to you), could fathom the mechanism) we are waiting (again) for an Einstein--- because we again are facing strange phenomena that needs explaining AND--- we don't like cheap (qft). That's not an explanation for the phenomena we observe. It's not a theory. It does not reveal why we need to be using wave math (of all things) to predict the chances of finding a particle here, or there. It does not explain--- what is going on behind the curtain. to make these effects be. It's kind of like had Einstein not explained gravity at all, and on year1 (instead of on his year10) he just said "Oh there are these fields around the earth...they just act on the moon and Make it move toward the earth, there is nothing being transmitted from earth to moon!". Anyone could have said that, back to Newton. But they didn't because it's cheap, incomplete. that's QFT. It's as weak as blaming god. I will however say that QFT is a bit less laughable than Pilot wave (which, the latter, a bit less laughable than Many worlds). So you've got that going I guess, but outside of being compared to crap attempts at making sense of QM, it is trash as a theory. We are waiting for an Einstein. For a proper theory that explains exactly what is going on -- what makes sensible -- the observed phenomena at this scale (just as he provided that sensibility for the macro scale). As for your Wave func? Obviously there is a wave function collapse. We stop using the math (the wave function) when it stops having applicability, such as when we measure the value of particle (eg, position, or spin). The math collapses, but that's just a poetic way of speaking. I have a mathematical function here which describes how this dime spins on a table over time while subject to gravity. But when Amy comes into the room and knocks the dime over so she can read the date on it, my spin-function collapsed, and I don't have any trouble explaining how this happened. Nor do I deny that it happened. My spin-function collapsed. Yes, that's what wave-function collapse means. It means there is (at once) no applicability anymore, because the conditions are no longer to which the function applies. Not a big deal. Trivial. Those who claim that the wave-func is something MORE than the mathematics we are here using to make predictions, need to specify what this mysterious thing is, where it is, and most importantly-- HOW THEY FOUND OUT that thing exists? Where is the evidence of this thing's existence? Isn't that important? To know that it exists--- before going around claiming spiritual nonsense like OMG THAT THING collapsed just now!! What is this, philosophy? Poetry? Novel making? This is physics --- They owe to explain WHAT it is and HOW they found out that it in fact exists, before they go talking about things it does like collapses. Make them act like a physicist (less like a philosopher, or Deepak Chopra) and you'll see that they have nothing. Out goes the collapse problem. Back it goes simply to "math applies, or not applies". Back it goes to--- waiting for an Einstein to explain phenomena at this scale, which our mathematics is working to describe (for some reason only the theory knows).
Anyone else find the ego quite visible ever since the blow-up with Kastrupp on TOE? Didn't really notice it before, now it seems quite obvious in hindsight.
A) Isn't, "faster than light" outside of time or rather timespace? B) Quantum mechanics to me seems to be so extensive that it requires specialists in different areas. No one understands it completely but you could have the people that do, all in one room at one table.
You can derive the basics of quantum mechanics in a few dozen pages. It doesn't require any specialists. It's one of the most simple theories in physics. The applications of quantum mechanics do, of course, fill libraries. What Tim Maudlin is talking about here, however, is one of the most trivial aspects of the theory... he just doesn't seem to understand it.
I always thought all of this was obvious to people, but i learned over time that people are very very confused even if they know perfectly well how to calculate in mikowsky space. Even when i was in high school the teacher who had a degree didn't understand that you could start in any reference frame and talk about all the effects as coming from velocity with respect to the background you chose, and the answer would turn out the same. Took me about 5 minutes to spot that the first time i ever looked at relativity, then when someone tries to tell you that your intuition is wrong it is kind of distressing that they are wrong and have a degree. Just take the twin paradox, the proper time always works out in the same ratio no matter what background you start with in euclidean space, where time dilation is "objective". And the same kind of thing applies just the same to length contraction, the only problem with this kind of view is when you change points of view along the way without accounting for the accelerated reference frame. I have had quite enough of people believing in principles they don't understand, especially when the principles are right, the problem is that in mamy cases the principles are stated in a form where it just reifies a certain representation and then people say "everything is relative" and they happily forget they don't understand what that means in all the resperentations of the theory they believe in. Or maybe some even say "there is no universal clock" or something silly like that, which os absolutely not true at all, everyone always agrees about every one elses light cones, and everyone elses definitions of time, there isn't just one universal time, but as long as lorentz symmetry is there and the causal structure is a light cone structure then there are "infinite universal clocks" using any one of them is perfectly fine.
Yeah, I frequently see the claim that QM is some ineffable mindfuck while relativity is relatively (see what I did there) simple and easy to understand but at least the interpretational difficulties inherent to quantum theory are acknowledged, analyzed and delimited by those who care about such things, while highly questionable claims about what relativity really means, that stem from confusing observation with reality, are accepted by the scientific establishment as proven dogma, like what you point out about time. If you search for "light compass" on here you'll find a guy trying to dispell the widespread misconceptions about what relativity means which I think you'll like, though it is sad that is where you have to go for such a thing.
In quantum mechanics we are measuring energy, momentum, angular momentum and charges. We can repeat many such measurements and then arrive at frequencies. We can never measure probabilities. That would require an infinite number of measurements.
@@lepidoptera9337 is probability distribution is the only we can observe tho? We posit the wave (function)? We can measure this or that and then cross reference data to see axiomatic nature but then things get weird. I'm dumb tho. Still trying to PhDs like Maudlin. I don't understand MW theories.
@@Micheal313 One can never observe a probability distribution. Those are abstracts, similar to the real numbers. One can only observe finite frequencies. There is nothing weird here. Quantum mechanics can be derived from the same assumptions as probability theory: that individual samples/experiments from a random sample set/physical ensemble are statistically independent. These assumptions are usually called Kolmogorov's axioms. Why are individual quantum mechanical measurements independent? Because of special relativity. The only "weirdness" here is the fact that we don't teach these trivialities either at the high school or the university level and so everybody and their grandmother's dog is suffering from DK about this. Folks just don't know what they don't know (even though all of this can be found in papers in the physics library) and they keep talking about their lack of education like as if it was a fact of nature. It isn't. All you have to do is to read the primary literature on the subject to understand what is going on. It's rather simple stuff that doesn't require anything beyond high school level algebra to understand.
@@lepidoptera9337fair enough but can you expand on how special relativity makes QM measurements independent? I appreciate this all thx. I prefer to hear real peoples perspectives over mainstream. I really don't understand what statistical significance independent is because aren't they dependent on a device for measurement?
@@Micheal313 All the events that can influence a local observer are inside the observer's backwards light cone. All the events that can influence the observer's future are in a light cone that contains more volume than the present one. The extra volume consists of spacelike separated events that are currently unknowable. Let's make an example. One of our Mars probes has a radiation detector on board. That instrument measures a sudden burst of radiation RIGHT NOW (in our local clock time here on Earth). It triggers the radio of the probe and the signal is now on its way to Earth. This will take roughly ten minutes, during which time we have no way of telling what has happened. Our future, ten minutes from now, will therefor be influenced by a completely unpredictable event. That is the source of uncertainty in quantum mechanics. This rather simple effect does, of course, not show up anywhere if we are only looking at non-relativistic quantum mechanics, which is how we usually teach QM in introductory classes. This is simply an artefact of our educational system which starts with a toy system that is, indeed, not "complete". The fully relativistic theory, OTOH, doesn't have this problem. It just happens to be much, much, much more complicated in mathematical terms.
If you look carefully the two situations are not the same, different experiments apply, to test the same inequality, because of what i said, for superluminal action at a distance you don't have the luxury of just considering any old timing that is outside the lightcones, you have to check individual surfaces of simultaneity.
I really don't see why there's a problem with giving up statistical independence, we are dealing with elementary particles not people. The results depend on what you measure and yeah perhaps the conclusion is that we may not be able to apply the scientific method at that scale anymore because the system cannot be measured without disturbing it. We could try a few experiments before giving up on that though.
49:00 - ALICE'S PARTICLE DOES NOT HAVE A STATE TO AFFECT REMOTELY. Only the system of both particles has a state. And that state does not exist in physical space. So speed of influence doesn't even make sense to talk about.
Tim Maudlin is THE GUY who takes all the pomp and circumstance off modern physics and helps ground us in remembering that despite all the "success" of our theories, literally none of them are actually "right."
But in insisting on the absolute evidence of non locality, he mystifies QM, without any conclusion how to solve the measurement problem. It's still unsolved, since ErwinSchrödinger put a cat into a box about hundred years ago. The 22noble experiments did not rule out locality and hidden variables.
What’s the difference between a hypothesis and a theory again ?!?
@@_TravelWithLove A theory has more evidence? Think it's not clear defined.
@@Thomas-gk42 my point is simply that there is an almost ecclesiastic nature about modern science, and Tim succinctly shows the emperor has no clothes and we don't have all the answers.
I don't even fully agree with Tim, I'm into all sorts of spooky esoteric shit that he would dismiss as "silly." It's just that he has a way of profoundly reducing the complexity of the disconnect in physics that shows there's waaay more out there to be solved.
@@Thomas-gk42Odd statement. He actually proposes interpretations that demystify QM and solve the measurement problem. How did you come to that conclusion?
Maudlin is a personal favorite of mine and I'm always happy to see more stuff from him online.
Definitely one of the most rewarding and insightful episodes I've seen on TH-cam! I think anybody who has any interest in quantum entanglement should watch this!
I remember reading somewhere that Feynman said something along the lines of “there are probably less than 100 people worldwide that understand relativity at a intuitive level. And probably less than 10 that understand quantum mechanics at an intuitive level.“ That always stuck with me.
Feynman was a joker who liked to pull other people's strings. He clearly managed to pull yours, whether he actually said that or not. ;-)
Actually he said that if you think you understand quantum behavior, you don't understand it.
It's a variation of a beautiful Irish expression: "If you're not confused, you don't really understand what's going on."
Those who understand Advaita Vedanta, and there are many (more than 100), understand quantum physics, non locality at least, and so-called spooky action at a distance (a misnomer to those who understand). Same, even more so, for those who have had out of body experiences and often for those who are deep meditators or attain samadhi. Reality is non local. Time, space and distance arise as universal consciousness attenuates to the brain and senses, which makes them ultimately, though inherently, illusory. Take up Advaita, with any luck it will become clear. Advaita simply means, not two (the One appearing as separate objects to the senses).
@@iamhudsdent2759 This overlooks the serious disagreement among advanced contemplative traditions. Dzogchen is at least as serious and rigorous as Vedanta yet fundamentally rejects and deconstructs the assertions of Vedanta both on philosophical and yogic grounds.
Before we make these huge leaps outside of the dicipline of dharma, if you will, we have to convincingly settle these issues within the discipline.
A really thorough explanation of basic concepts of EPR, Bell's theorem and features of quantum mechanics. Thank you and your guest for this amazing discussion.
I hope you'll have Tim Maudlin on the program more often. This was really a phenomenal conversation.
Thank you Timothy & Prof. Maudlin for such a wonderful episode. I will enjoy re-watching many times over in the coming next weeks!
Perfect - I've waited for this quite a time. Somebody breaking down this whole issue in a way I get to understand it.
Thank you very much guys and deep gratitudes.
This is the best physics podcast episode I have ever heard!
Man I can't tell you how much I appreciate the fact that you're willing to lean in to some bold technical confrontation for the better of perspective learning and understanding. Thank you for what you do, hope it keeps growing!
Thanks both Tims!
This was an amazing exposition with a lot of historical context. I’m not a physicist but a Statistician and I found the whole discussion very illuminating, especially the tables explaining Bell’s inequality. Wonderful job!
Thanks. Finally a thorough walk through instead of the 10 minute explanation one usually finds on youtube.
Thirty years ago I joined a class with the simple name "foundations". It was optional and not very popular among fellow students so we could discuss the topics (which EPR was one of) in a small group. I liked it very much and kept the syllabus and lecture notes until this day.
Very cool discussion. A great example of how relatively straightforward math can guide our intuition on very deep questions.
This is so good. I wish all science communicators talked like this.
This is the perfect interview! My compliments to Timothy.
I have to compliment the two Tims for this interview. I think that it explains the key points in EPR and Bell's Theorem with more clarity than I have seen before.
I disagree when Maudlin says Einstein's issue was just nonlocality. If you read Einstein he was clearly also heavily critical of the nonrealism of the Copenhagen school which inherently falls out of its indeterminism. He gave a precise example using atomic decay pointing out that if you accept it is indeterministic then you cannot admit the decay ever occurs or doesn't occur until it is observed because the wave function does not describe a moment of decay. That's why Einstein asked Abraham Pais "do you really believe the moon doesn't exist when you aren't looking at it?"
You cannot salvage realism by positing that the wave function is an ontic state itself either (that the atom's ontic state is not decay or not decay but the state described by the wave function) as Eugene Winger showed this still forces you to abandon realism ("Wigner's friend") that is, unless as Bell argued (in his article "Against Measurement") you also accept the collapse is ontic as well (in the sense of Penrose objective collapse).
Yet if you accept objective collapse then you need a theory of measurement, i.e. it implies quantum mechanics is an incomplete theory, which was Einstein's position in the first place. Einstein's did have criticisms of nonlocality, but he was also critical of the implied nonrealism of the Copenhagen school (at least in the sense that it is commonly formulated) that forces you to abandon the existence of an objective reality independent of the observer. He was quite clear on this in his writings.
Even as Maudlin points out the EPR paper never mentions nonlocality but instead a "criterion for reality" where locality is only implicitly assumed. The main point of the paper was incompatibility with realism. While you can argue correctly that the paper in fact, due to its implicit assumptions, only shows an incompatibility with _local_ realism, if you read Einstein's other writings he gives other arguments that don't depend on locality, because his main concern was realism, and ultimately locality was secondary, but still important because he thought locality is needed to make it compstible with General Relativity (he even dabbles into superdeterminism in onr paper he wrote but instead calls it "overdeterminism").
Thanks for that point
this was great. U did a great job writing down the math so I could follow along with his talking. I remain unconvinced that reality does not obay Bells inequality. The odd/even up/down meassurements failed to show me how it was broken. I have tried to understand this many times, so it's not your fault. Your video was great!
Interesting. What part you did not follow!
@@grumpytroll6918 When he says that the meassurements breaks Bells inequality, they just don't break Bells inequality. It is entirely plausible to get those meassurements without breaking the inequality. So I guess that was the part I didn't follow?
@@synx6988 which measurements are you referring to?
@@grumpytroll6918 I mentioned them in the original post u responded to. The odd/even up/down meassurements
just more specifically why do they not break it? Just trying to understand where the misunderstanding might be.
This was great! I'll be watching it again. Bell's theorem is difficult enough without being misled by faulty concepts/terminology -- as happens in so many videos about reality vs locality vs hidden variables.
Thank you Tim Maudlin for covering it for us in this venue. Great work Timothy.
Feynman went so far as to explain pilot wave theory in his lecture-based book _QED_.
Well done, fellas. Was an awesome watch. Peace ✌️ 😎.
Loved conclusion. Progress can be said to have been made if clear questions are raised. Additional/hidden variable theories naturally raise the question "What variables?"; Collapse theories naturally raise the question "How/why does collapse occur?"; Many Worlds theories are too obscure and you are left to asking "What question can I ask?
Thank you both for sharing this beautiful video !! Intelligent and insightful scientific education and conversation !! Outstanding !!
53:30 - And there it is - it's exactly that simple. Both particles have access to their shared state, at all times, regardless of how far apart they are. The theory IS non-local, and that's just all there is to it. This isn't something that happens "through spacetime." It's simply "a connection" that exists in some way we don't know how to explain.
Thank god man, I have been doing citizen science for over 20 years and I was puzzled by many of these theories. Finally someone who makes more sense.
Well done! This was complete and must be convincing for anyone who watches.
I love your deep dives ❤❤❤
As always, I really appreciate you uploading these- thank you for the great insights/discussion!
Thanks for this well prepared interview. The agenda / logical "storyline" was very supporting in getting to grips with fundamental issues like determinism, non-locality etc.
That determinism-locality-correlation discussion was excellent - great podcast, Tims!
The articulation of the available explanations based on the 3 categories at 2:36:00 was super helpful!!
2:26:20 - If we assume the perfect correlations assumptions is true (as can be experimentally verified) EPR just proves that locality implies determinism. What Bell's theorem proves is that if you assume determinism you must have non-locality. From EPR + Bell, we deduce that locality implies non-locality, so our initial assumption is false. Any theory of the world must be non-local.
As noted there is always the underlying assumption of science existing... (statistical independence)
@@eitanporat9892 And if statistical independence is not true? If tomorrow someone proves that nature is completely deterministic, would that nullify all the scientific progress that we have made and all the knowledge that we have gathered? Of course not. The insistance that statistical independence must be true in order for science to exist seems not justified and franky based in ideology.
I'm not really sure how this could be controversial. The classic demonstration of bell's inequality is polarized light filters. Each filter removes half of the photons based on their spin.... when there is one filter. When there are two filters, there's a relationship between the angle of the filters and how many photons go through - minimal at a 90 degree (or 270)/perpendicular alignment, maximal at a parallel or 0 degree alignment (or 180, I suppose). This, in itself, chucks relativity right out the window, but things get even more fun.
If we add a third filter between the two and set it at a dissimilar angle to the prior - MORE photons get through the system, with an uncountably infinite polarizing filters/angles converging on unity. Barring other losses.
The photons have to know what is going on ahead of them in the system so as to know how many get reflected off of the filters. At least... to the limits of what has been experimentally tested (I've yet to review the nobel work discussed).
It should be obvious that determinism is not local.
One could set up experiments consisting many light-seconds, to allow for locally random behavior to alter a polarizing filter and then try to measure changes to the system to probe at just how nonlocal it is. If the "quantum noise generator" locally is flippng my polarizing filter all over the place, then we would expect one of two absurd things to happen - either the system instantly adapts to change how many photons pass (which could be easily adapted for superluminal communication) - or ... somehow the photons of 3 light seconds ago knew what state the light filter would be in when they hit it, now.... which... can still potentially be utilized for superluminous communication (but there is a catch).
Or...... maybe the phenomenon breaks down at a great enough distance... for... reasons.
Regardless, relativity does not survive sunglasses.
@Aim54Delta how does that show relativity is wrong. It's also possible to retain locality if the future and past are determined at the same time but also if the development the universe is governed by fractal like relationships.
@@onesquirrel2713 I wouldn't call it ideology. Maudlin explains how lack of statistical independence makes life a LOT harder (if not impossible) for experimental science. That doesn't mean that it's false, but it would be a huge blow to science.
Probably the single clearest discussion about the measurement problem I've ever listened to.
It's just too bad that there is no such thing as a measurement problem. There are only people who didn't read von Neumann's book from 1932 in wich he explains how measurement works. Read chapter six. ;-)
@lepidoptera9337 Personally, I think statistical independence is violated in Bell experiments, and simply that there's some sort of retrocausal process involving the detectors and detected particles. This means keeping locality, thus keeping all the equations of special and general relativity the same (since arrow of time is really only ever assumed in the first place for thermodynamics reasons, though Boltzmann argued against doing such a thing), as well as the predictions of effective field theory. Basically the only arguments I've ever heard against this are vague philosophical ones about how time traveling tobacco companies could scam people or something
@@etc4xg The statistical independence is between consecutive measurements. We have to be able to predict the outcome of the next measurement from the previous n measurements to talk about dependence. Can we? No, in general we can't. That inability to predict (lack of correlation) is what we mean by independence. What matters is that the sequence of events and their precise timing doesn't matter. Only relative event frequencies matter. That is the underlying assumption that leads to unitary, linear dynamics.
It is, of course, not true that every measurement is independent. The measurements of the orbital position of a planet are not (they are, indeed, highly correlated) and that's why the formula for planetary motion is not linear. Quantum theory is the description of a very special kind of system that is NOT guaranteed. We have to test if the independence condition holds on the actual physical data. If it does not hold, then we can't apply the formalism. This is such a triviality that the introductory textbooks are not even mentioning it. Having said that, anybody who wants to be taken seriously about the foundations of quantum mechanics better know this. Most quantum mystics don't seem to know any of this, or if they do, then they are lying to the general public about it because it destroys the entire false mythology around QM.
Yes, this was a very rewarding 2h40min! So much so that I will be viewing it again and again. The one lingering question for me is why completeness is required of the theory. From whence does that come? Did I miss something? Or does this derive from some vague idea like "beauty"?
Where does quantum mechanics come from? Two sources: Kolmogorov's axioms and relativity.
Love Maudlin, thanks for the great interview, Tim N :)
Maudlin is doing a great public service by explaining this stuff
Thanks for this. Been working through Maudlin’s work and it has been a rough go. This video really helped me understand why Maudlin’s ideas haven’t caught on. It’s harder work for not a lot of effect. All the calculations become harder but I am not seeing the value from making it harder.
Feynman’s ideas at least made the calculations easier with integrals, but this seems like a project that would take decades to even touch the reliability of the standard model.
He could be right, but I can see why few people want to take up the task of working with it.
No, he is not even right. Neither was Feynman, by the way, but Feynman's initial formalism can be rescued and it is useful as you said. There are, however, hints that it is extremely naive and that there are better (and much shorter) ways to get to the same results. But proving that seems to require some extremely hardcore math and it may take another couple of decades before the actual mathematical picture will fully emerge.
@@lepidoptera9337 I agree he is probably not right. While his project may be useful, it also extremely hard to work with and mine good information from.
Agree with Feynman. He was “right” in the way Newtonian dynamics was. A good foothold for further exploration but obviously missing some critical information. Maudlin doesn’t even have that,
@@fakename4683 What would be useful is if we would finally start teaching physics rationally in high school. Any of the things Maudlin talks nonsense about can be explained trivially at the level of high school physics. The reason why people are utterly confused about the microscopic world is entirely psychological. We are spending most of K-12 to instill a 19th century (and thus wrong) mental model about the world into kids by using the 19th century (also wrong) teaching method that uses the threat of withheld parental love as retaliation for bringing home failing grades. That is ridiculous, both on the educational and the science side.
@@lepidoptera9337 Rational is slippery subject to me. I have always been a bit of a proponent of dialetheism so I don’t know how much I think a rational study of physics would accomplish.
Do agree that HS infantilizes many subjects. Biology is still stuck on Mendel for some reason.
@@fakename4683 The difference between rational and irrational is made pretty obvious in politics, with the irrational side being patently laid bare by folks like Trump and Putin. That is what "irrational" looks like: it eventually starts threatening your life. ;-)
Oh yeah Nick Herbert! I read his book about 20 years ago. I prefer Tim Maudlin's presentation here - he makes it very easy to understand yet it is fascinating.
Awesome exposition. Clarifying question - Isn't the initial assumption of entanglement - that the 2 particles are entangled from the very beginning....isn't that assumption, in itself, a hidden variable? For example, the 2 different colored socks....the fact that it was already pre-determined that they will be of different colors...that pre-determination, in itself, is a hidden variable. And that pre-determined information is carried with each sock, no matter how far apart they are. And therefore, no action at a distance is needed.
There is nothing "hidden" about entangled states. They exist because of local conservation laws. That is not a physical mechanism. It's the absence of a physical mechanics that breaks the conservation.
This is a great presentation. Thanks a lot!!
Excellent. Half way through and already infinitely better than all the pop physicist combined
The evolution of scientific understanding is the evolution of our thinking and I appreciate that he never loses sight of how we think about things and is concerned about it.
Tim is such a clear thinker! Makes you consider that a physics curriculum should have some mandatory philosophy classes.
I am among those who resists accepting “non-locality”. I accept that this may be my problem, and I remain open to letting go of my attachment to causality and locality. But I remain VERY suspicious that non-locality can’t really be used to transmit information as a speed higher than C. Otherwise, I stuck to EPR
I appreciate anyone thoroughly examining theorems. Those things in the ether as Helena Petrovna Blavatsky called it become increasingly theoretical and even their proof in physics becomes increasingly subjective. My intuition however guides me towards the multiverse, non determinism, non linearity, non finality and non locality. I also find it logical. We have to keep in mind that we are dealing with the Infinite.
53:48 There is spooky action at a distance only if you think of the states of the two particles to be to be independent of each other, whereas in reality they are really described by a single state which entangles the two particles, so that when a measurement is made on any one of them, it collapses the entire entangled state to one of its components, or if you are uncomfortable about collapses then you can always assume that in different universes the outcome is different, as in the many worlds interpretation. Or if you are uncomfortable about many worlds, you can assume the quantum block universe where the wave function of the universe is a unique wave function which has been existing forever and all outcomes of all experiments are all predetermined. At any rate when the particles start off there is no way of knowing what momentum the particles carry because this lies at the heart of quantum mechanics. It's always the case that there is a certain probability amplitude associated with each particular momentum. So it's not a case of Bertleman's socks.
56:53 Any residual indeterminism destroys the perfect correlation? No it doesn't, the states at the beginning are a linear superposition of all possible zero momentum two particle states and in this sense the momenta are perfectly undetermined and yet perfectly correlated since each component of the entangled state is a zero momentum state in which the two particles have opposite momenta.
58:17 There is indeed a unique state in both cases and that's it is a linear superposition of all possible zero momentum two particle states.
At this point I believe I have to stop listening to the lecture anymore.
Your first point formulates entanglement in a way that overlooks what the spooky action at a distance issue is in the first place. For instance, you use the phrase "collapses the entire entangled state" without taking into consideration that this collapse, naively formulated, leaves unanswered how such a mechanism can be accomplished across arbitrary (spacelike separated) distances in the first place. In other words, you smuggled spooky action at a distance into the collapse.
Your second point misunderstands the use of indeterminism in this context. All that is being said here is that if there is indeterminism to Alice's measurement after Bob does a measurement, then there can't be a perfect correlation, because a perfect correlation requires a uniquely specified outcome (the opposite of Bob's measurement). There is no controversy here.
Your third point also misunderstands the discussion about determinism.
I would encourage you to revisit these topics (and/or the video) with a greater appreciation of the complexities and subtleties of the issues involved.
@@TimothyNguyen It can be accomplished across arbitrary space like separated distances because the real space in which all this plays out is a multi particle Fock space in which the wave-function appears as
\int d^3p (psi(p,-p)+psi(-p,p))(phi(p)phi(-p))|0> where the psi's are wave-functions while the phi's are creation operators of the scalar field. For fermionic fields there would be a change of the superposing sign. When a collapse takes place, either of the two components get chosen, when psi(p,-p) gets chosen, the first particle gets assigned momentum p and the second one -p, and similarly for the second component. Since the position space label doesn't even make an appearance, it follows that that this would happen irrespective of where the particles are, or how far they are separated.
Your rebuttal of the second point makes no sense. What do you mean by the statement, if there is indeterminism to Alice's measurement after Bob does his measurement, by the standard understanding, there can never be any indeterminism to Alice's measurement when Bob does his measurement, they are always perfectly correlated. What I am trying to say is the results of the measurements are completely undetermined beforehand since the particles are in a linear superposition of all possible momentum outcomes besides being in the linear superposition shown above, and the latter allows them to be perfectly correlated to each other as well.
Regarding the third point I believe what I have said is absolutely clear.
Trouble with Maudlin is the standard trouble with philosophers, they don't appreciate the physics well enough to make sufficiently well-informed statements.
Sorry for having been this harsh, I really shouldn't have said some of the things that I did. Please don't take any offence if you can.
@@TimothyNguyen There is no such thing as collapse in quantum mechanics. That meme has to disappear from the discussion. It causes nothing but consistently wrong mental models of reality. The entire idea that one measurement takes place before the other is also just intellectual nonsense. That order of events only exists for a limited class of observers. It is preferred by the observer in the center of mass system, of course. A relativistic outside observer, however, can correctly claim that it's not A before B but B before A. That claim can, of course, not change the outcome, hence there can be no causal link between the two measurements, unless we are willing to throw relativity out at once.
@@schmetterling4477 That's the point. Relativity has it's limitations as currently formulated.
Maudlin's explanation starting at 1:40:00 is really helpful
Conservation of Spatial Curvature:
Both Matter and Energy described as "Quanta" of Spatial Curvature. (A string is revealed to be a twisted cord when viewed up close.)
Is there an alternative interpretation of "Asymptotic Freedom"? What if Quarks are actually made up of twisted tubes which become physically entangled with two other twisted tubes to produce a proton? Instead of the Strong Force being mediated by the constant exchange of gluons, it would be mediated by the physical entanglement of these twisted tubes. When only two twisted tubules are entangled, a meson is produced which is unstable and rapidly unwinds (decays) into something else. A proton would be analogous to three twisted rubber bands becoming entangled and the "Quarks" would be the places where the tubes are tangled together. The behavior would be the same as rubber balls (representing the Quarks) connected with twisted rubber bands being separated from each other or placed closer together producing the exact same phenomenon as "Asymptotic Freedom" in protons and neutrons. The force would become greater as the balls are separated, but the force would become less if the balls were placed closer together. Therefore, the gluon is a synthetic particle (zero mass, zero charge) invented to explain the Strong Force. An artificial Christmas tree can hold the ornaments in place, but it is not a real tree.
String Theory was not a waste of time, because Geometry is the key to Math and Physics. However, can we describe Standard Model interactions using only one extra spatial dimension? What did some of the old clockmakers use to store the energy to power the clock? Was it a string or was it a spring?
What if we describe subatomic particles as spatial curvature, instead of trying to describe General Relativity as being mediated by particles? Fixing the Standard Model with more particles is like trying to mend a torn fishing net with small rubber balls, instead of a piece of twisted twine.
Quantum Entangled Twisted Tubules:
“We are all agreed that your theory is crazy. The question which divides us is whether it is crazy enough to have a chance of being correct.” Neils Bohr
(lecture on a theory of elementary particles given by Wolfgang Pauli in New York, c. 1957-8, in Scientific American vol. 199, no. 3, 1958)
The following is meant to be a generalized framework for an extension of Kaluza-Klein Theory. Does it agree with some aspects of the “Twistor Theory” of Roger Penrose, and the work of Eric Weinstein on “Geometric Unity”, and the work of Dr. Lisa Randall on the possibility of one extra spatial dimension? During the early history of mankind, the twisting of fibers was used to produce thread, and this thread was used to produce fabrics. The twist of the thread is locked up within these fabrics. Is matter made up of twisted 3D-4D structures which store spatial curvature that we describe as “particles"? Are the twist cycles the "quanta" of Quantum Mechanics?
When we draw a sine wave on a blackboard, we are representing spatial curvature. Does a photon transfer spatial curvature from one location to another? Wrap a piece of wire around a pencil and it can produce a 3D coil of wire, much like a spring. When viewed from the side it can look like a two-dimensional sine wave. You could coil the wire with either a right-hand twist, or with a left-hand twist. Could Planck's Constant be proportional to the twist cycles. A photon with a higher frequency has more energy. ( E=hf, More spatial curvature as the frequency increases = more Energy ). What if Quark/Gluons are actually made up of these twisted tubes which become entangled with other tubes to produce quarks where the tubes are entangled? (In the same way twisted electrical extension cords can become entangled.) Therefore, the gluons are a part of the quarks. Quarks cannot exist without gluons, and vice-versa. Mesons are made up of two entangled tubes (Quarks/Gluons), while protons and neutrons would be made up of three entangled tubes. (Quarks/Gluons) The "Color Charge" would be related to the XYZ coordinates (orientation) of entanglement. "Asymptotic Freedom", and "flux tubes" are logically based on this concept. The Dirac “belt trick” also reveals the concept of twist in the ½ spin of subatomic particles. If each twist cycle is proportional to h, we have identified the source of Quantum Mechanics as a consequence twist cycle geometry.
Modern physicists say the Strong Force is mediated by a constant exchange of Gluons. The diagrams produced by some modern physicists actually represent the Strong Force like a spring connecting the two quarks. Asymptotic Freedom acts like real springs. Their drawing is actually more correct than their theory and matches perfectly to what I am saying in this model. You cannot separate the Gluons from the Quarks because they are a part of the same thing. The Quarks are the places where the Gluons are entangled with each other.
Neutrinos would be made up of a twisted torus (like a twisted donut) within this model. The twist in the torus can either be Right-Hand or Left-Hand. Some twisted donuts can be larger than others, which can produce three different types of neutrinos. If a twisted tube winds up on one end and unwinds on the other end as it moves through space, this would help explain the “spin” of normal particles, and perhaps also the “Higgs Field”. However, if the end of the twisted tube joins to the other end of the twisted tube forming a twisted torus (neutrino), would this help explain “Parity Symmetry” violation in Beta Decay? Could the conversion of twist cycles to writhe cycles through the process of supercoiling help explain “neutrino oscillations”? Spatial curvature (mass) would be conserved, but the structure could change.
=====================
Gravity is a result of a very small curvature imbalance within atoms. (This is why the force of gravity is so small.) Instead of attempting to explain matter as "particles", this concept attempts to explain matter more in the manner of our current understanding of the space-time curvature of gravity. If an electron has qualities of both a particle and a wave, it cannot be either one. It must be something else. Therefore, a "particle" is actually a structure which stores spatial curvature. Can an electron-positron pair (which are made up of opposite directions of twist) annihilate each other by unwinding into each other producing Gamma Ray photons?
Does an electron travel through space like a threaded nut traveling down a threaded rod, with each twist cycle proportional to Planck’s Constant? Does it wind up on one end, while unwinding on the other end? Is this related to the Higgs field? Does this help explain the strange ½ spin of many subatomic particles? Does the 720 degree rotation of a 1/2 spin particle require at least one extra dimension?
Alpha decay occurs when the two protons and two neutrons (which are bound together by entangled tubes), become un-entangled from the rest of the nucleons
. Beta decay occurs when the tube of a down quark/gluon in a neutron becomes overtwisted and breaks producing a twisted torus (neutrino) and an up quark, and the ejected electron. The production of the torus may help explain the “Symmetry Violation” in Beta Decay, because one end of the broken tube section is connected to the other end of the tube produced, like a snake eating its tail. The phenomenon of Supercoiling involving twist and writhe cycles may reveal how overtwisted quarks can produce these new particles. The conversion of twists into writhes, and vice-versa, is an interesting process, which is also found in DNA molecules. Could the production of multiple writhe cycles help explain the three generations of quarks and neutrinos? If the twist cycles increase, the writhe cycles would also have a tendency to increase.
Gamma photons are produced when a tube unwinds producing electromagnetic waves. ( Mass=1/Length )
The “Electric Charge” of electrons or positrons would be the result of one twist cycle being displayed at the 3D-4D surface interface of the particle. The physical entanglement of twisted tubes in quarks within protons and neutrons and mesons displays an overall external surface charge of an integer number. Because the neutrinos do not have open tube ends, (They are a twisted torus.) they have no overall electric charge.
Within this model a black hole could represent a quantum of gravity, because it is one cycle of spatial gravitational curvature. Therefore, instead of a graviton being a subatomic particle it could be considered to be a black hole. The overall gravitational attraction would be caused by a very tiny curvature imbalance within atoms.
In this model Alpha equals the compactification ratio within the twistor cone, which is approximately 1/137.
1= Hypertubule diameter at 4D interface
137= Cone’s larger end diameter at 3D interface where the photons are absorbed or emitted.
The 4D twisted Hypertubule gets longer or shorter as twisting or untwisting occurs. (720 degrees per twist cycle.)
How many neutrinos are left over from the Big Bang? They have a small mass, but they could be very large in number. Could this help explain Dark Matter?
Why did Paul Dirac use the twist in a belt to help explain particle spin? Is Dirac’s belt trick related to this model? Is the “Quantum” unit based on twist cycles?
I started out imagining a subatomic Einstein-Rosen Bridge whose internal surface is twisted with either a Right-Hand twist, or a Left-Hand twist producing a twisted 3D/4D membrane. This topological Soliton model grew out of that simple idea. I was also trying to imagine a way to stuff the curvature of a 3 D sine wave into subatomic particles.
.----------------------
String Theory is an unmitigated bs .
Part of my job involved running a 6 session anxiety management course. At the last session (consolidation and feedback) I asked if there were any last questions. A man who had attended every session said .. “See that anxiety .. what do you do about that?” Now I know how he felt. 😊 He eventually overcame it BTW.
Being serious .. I was tired and fell asleep 💤 with Bertlmann’s disembodied socks 🧦 meandering through my consciousness. Will watch again. 😀
Does anyone know why in the GHZ thought experiment, when all three take measurements in the X direction it has to be odd? I cant follow the argument because I dont know why this has to be true
Here we go, thanks this looks pretty good
Superb interview by Timothy.
Interview Professor Jean Bricmont on Bell's Theorem also! Tim has hosted Professor Bricmont at NYU!! Bricmont points out that even Stephen Hawking did not understand Bell's Inequality nonlocality. Very fascinating indeed. Professor Basil J. Hiley, the collaborator of Bohm, also emphasizes how most physicists do not understand nonlocality.
Firstly great job to both Tim and the host for clearly articulating the key ideas.
I do however disagree with Tim’s dismissal 2:29:40 that “there is nothing that would count in a proper sense with a theory that you call QM.”
To understand Quantum Mechanics the key conceptual paradigm shift that one needs (and Tim refuses to accept) is that particle properties don’t have any reality until they are measured. The host tries to raise this point from 2:22:40 to which Tim essentially dismisses the question on the grounds that EPR proved that the local theory must be Determined. Whether intentionally or unintentionally Tim conflates“reality” with Determinism, and unfortunately out of politeness or more likely out of being unable to follow Tim’s train of thoughts, the host doesn’t confront him on it.
Let’s break some things down.
EPR don’t prove anything. They certainly don’t claim to prove that locality plus spooky action at a distance implies determinism. And in my opinion they don’t even prove their actual claim that the wavefunction is incomplete.
EPR define reality as being able to predict the outcome of a property with 100% accuracy without disturbing it. They then show that it’s possible via entangled pairs of particles to either determine the momentum of an entangled partner without disturbing it or the position of an entangled partner without disturbing it and so they conclude both realities must exist. They then claim that because the Heisenberg uncertainty principle (a consequence of the theory of quantum mechanics) cannot simultaneously give definite values for both the position and momentum of a particle quantum mechanics must be incomplete.
The problem is the EPR argument deals with counterfactuals. There is only one entangled pair so P and Q cannot be known simultaneously. If one knows the position with 100% accuracy the fact that one “could” have measured the momentum doesn’t make it 100% predictable (for the same experimental run) and therefore, using EPRs own definition of reality, the correct conclusion is that P isn’t real. Indeed, QM/Heisenberg ensures the momentum isn’t known with 100% certainty. So the EPR conclusion (that the wave function is incomplete) is derived from a logical fallacy. EPR themselves seem aware of this and by their own admission state “indeed we would not arrive at this conclusion if we had insisted that two or more physical quantities can be regarded as simultaneous elements of reality only when they can be measured simultaneously.” This is stated in spite of the fact that their own definition of reality doesn’t strictly cover this edge case. If however we enlarge their definition so that all things that hypothetically could be known with 100% certainty about a system without disturbing it must be real then it leads to some weird conclusions about “reality” - for example we can ask the question via POVM is the particle at position x1 or not. So the partner has a reality of being here at x1. But we could equally have asked if the particle was at x2. So by this definition the partner also has a “reality” of being at x2, indeed it has a reality of being everywhere. It is well known that arguing about counterfactuals leads to apparent paradox’s in QM even within QM setups that don’t involve Einstein’s “reality” feature (see Hardy’s paradox). However QM is clear, only what you measure can be a fact. You cannot speak of any reality of things that haven’t been measured. Or as Peres’ put it “unperformed experiments have no results.”
What has always surprised me about the EPR paper is that Einstein uses the QM formalism namely the EPR state as a tool to make claims about reality, and at the same time uses the formalism via the Heisenberg uncertainty principle to argue that the formalism is incomplete. But if it were true he would not only have proven a fact about reality and QM( namely that QM doesn’t describe reality completely), he would also have proven that QM itself was inconsistent with itself. This is clearly silly and why Einstein didn’t realise it I cannot fathom.
EPR never made any claims about determinism. So surprised was I to hear this claim that I went back to the paper and reread it again to confirm I hadn’t missed anything. Bell has taken quite a liberty it seems to attribute this to EPR. While Tim explains this is a natural inference of EPR, all he really shows is that knowing the state of one particle in an entangled pair “determines” the state of another if it is measured in the same basis. There’s really no link to the EPR paper, except the use of entangled pairs and even that predates EPR going back to Schrödinger. I personally think Determinism is a confusing word to use because it suggests that everything is deterministic when really the only thing that is meant is that the correlations are 100%, and therefore they must be mutually determined by something.
Well call it Determinism if you like but Bell is definitely assuming that there is at least one variable that is real, in the sense that it always has a value and follows some deterministic causal dynamics (essentially a classical particle property) and what he shows is that such an additional variable cannot explain quantum correlations.
Now you can either take this as very strong evidence to give up on an underlying reality, and accept QM as it is (the particles were determined to be 100% correlated upon being measured because they were in a state that was quantum correlated), or you can dig your heels in and say “No! there must be these real determining variables but they move around instantaneously finding their partners and telling them what to do and btw they do so without signalling faster than light.”
Not only is the theory of non-local hidden variables more uglier and complicated than QM but after nearly 100 years of trying (yes de Broglie wrote the first pilot wave theory in his thesis in 1924), nobody has been able to make it work. While Bohm could explain single particle spatial interference problems like the double split experiment they still can’t explain well spin or even entangled particles (the very subject of this video) and let’s not even mention quantum field theory. Quantum mechanics explains all these things easily. You just have to get over your hang up on underlying reality. The wave function isn’t real (there’s no non-local physical collapse). The wave function encodes the probability of possible outcomes. When you make a measurement you learn something about the world, but the possibilities are highly constrained such that once you learn this, many other parts of the jigsaw are automatically then forced on you. QM is simple, elegant, and profound but you need to shift out of the classical paradigm to make sense of it.
Thanks, that was great! I have a small question about the experimental setup. Suppose Alice's lab is on the North Pole and Bob's lab is on the Equator, how would they have to place their coordinates system to observe the perfect anti-correlations? For example, if we take the spin property and Alice makes a measurement with the magnetic field along the z direction, what would be the "z direction" for Bob?
That depends on the parallel transport from one place to the other. A tunnel will give different results than mirrors, which will give different results than glass fiber would.
Thanks so much Dr Tim and professor Tim Maudlin. So in-depth. Thanks Dr Nguyen, without your explanation, i wouldn't have fully understood the core concepts.
Given all that, it is perfectly plausible to imagine superluminal interactions that are never the less local onnthe same footing as other interactions, butbby a superluminal definition of locality, in that case and applying to bell, the action at a distance is only spooky if the effect persist for the truely simultaneous measurments, and so either you measure all the definitions of simultaneous measurements and find the inequality still breaks or you find some deviation with no proper inequality breaking at exactly infinite speed interactions. This means that for superluminal action at a distance you either get a positive result which breaks lorentz symmetry or you don't, and if you don't for one definition of simultaneous events you still have infinite other definitions to test at the same point in space for a given time, so it cannot ever be fully ruled out that these effects vreak lorentz symmetry. Which leads to the conclusion that you cannot ever fully rule out locality.
A huge point that gets glossed over often is...isn't it true that since the two entangled wave/particles are separated in spacetime they have no set causal order, thus no causal relationship? Correlations that aren't causal, so fundamentally neither outcome causes the other. Also, if the outcome is set when they are entangled, you can argue that's local since they are local to each other at that moment of entanglement.
I think your last sentence is correct, with a slight modification -- IF the outcomes were set when they are entangled, that would indeed be a locally created correlation. And I think that what Bell's Theorem shows is that nature is NOT local in the sense that the outcomes CANNOT be set when they are entangled.
What I would say is that it APPEARS that's what Bell's theorem says. But I think there is a nuance that's not part of the considerations. And that is that neither wave/particle has a set outcome until they are entangled, so they share a probability that resolves together at the point of entanglement, but that's done by quantum walking all possible outcomes and both identifying the exact circumstances by which each will resolve. So that information allows them to immediately decide how they will resolve in what we call the future. This is from the birdseye a non-evolving quantum system, almost like a frozen unit of time. It's deterministic but fully derived from probability, so it doesn't function like a hidden variable. It's local but has non-local elements, because the context for the joint resolutions must be characterized as future-looking. But if all systems are behaving identically, that determined context is explained, because all systems are doing the same deterministic walks. And with that one stroke, you suddenly have a quantum block similar to the block relativity suggests. From inside each system, they are perceived to transition from unresolved to resolved, with outside systems always having already resolved so there's always a firm background against which to resolve. But the viewpoint inside a system is just skewed, as all systems timelessly resolve at the point of entanglement. @@rfyl
I appreciate Nguyen's efforts to reconstruct how people got the wrong impression of Bell's work
Take time travel for example, unrelated to bell kind of. If you consider instantaneous travel between points, you have to travel along a surface of simultaneity, meaning what points in the spacetime you can reach instantly is dependent on coordinates, if you ask about what happens for worm holes or instantaneous/superluminal travel from a single point of view aka frame of reference aka coordinate system, it is obvious that no time travel is possible. To get time travel you need to be using different coordinate systems for travel in one direction vs the other, and so you can zig zag backwards in time along the surfaces of simultaneity. The confusion is that when you are talking about different coordinate systems for subluminal travel it is fine to consider parts of the problem from different points of view you will get the same results, but if consider superluminal travel that isn't the case anymore, and so we should stop confusing ourselves with it. To properly consider superluminal travel you need a foliation, then you can only zig zag towards the future, if you take the results from one point of view and consider the return trajectory from a different point of view you simply rotate both previously overlapping instantaneous trajectories in such a way as to male them still overlap but now representing a finite velocity, one way is a space like vector and the other way is the opposite space like vector, by changing perspectives for both you always end up with overlapping trajectories, if you then consider rotating one of them without rotating the other you are nlw changing the local space time events traveled through and arrived as, which is CHANGE in the causal structure! This is not what coordinate transformations are supposed to do, the superluminal grandfather paradox is a consequence of breaking causality by design, not by changing causality with applying laws of physics.
If position is a quantum property, how does it make sense to say Alice has one particle and Bob the other. Doesn't that mean until there is a measurement both particles are at each of Alice and Bob's labs?
Position is not a quantum property. Position is a property of the classical detector system. The only quantum properties are energy, momentum, angular momentum and charges. A and B are events where field energy is being absorbed by a detector. Before those absorption processes happen, there are no events A and B.
@@lepidoptera9337 what if you label the particles before they leave the source?
@@CrowMagnum There are not even particles here. What we are detecting in quantum mechanics is (field) energy. Energy is a system property. It's not a thing. One can't put a label on it. One can technically entangle e.g. the spins of an electron-positron pair, but the angular momentum property doesn't know anything about the charge property. These are completely independent quantum numbers. Think of all these properties as the (orthogonal) basis vectors of a coordinate system. We pick two random vectors and entanglement makes sure that the two vectors add up to zero. No matter where these two vectors are pointing, the sum still stays zero. We propagate these two vectors through physical space without turning them... the sum of the two vectors at the other end is still zero. There is really not much magic here.
@Tim Maudlin. Could you tell me if the EPRB experiment has ever been done without the use of magnets or other devices, only the particles and the screens? And if yes, what the results were? Thank you.
I don't know what that means. These experiments are about the consequences of entanglement on measurements that are not in the same place and/or at the same time. Measurement in physics is always done "with devices". That's the definition of "measurement".
@@schmetterling4477 a screen is a measuring device.
What am I not getting. So if Anne used -60 deg and Bob uses +60 deg, are the filters not really just 60 deg apart from each other… so cos(60)^2 is 25% anti correlation which to me sounds possible to achieve
Please interview Physics Professor Basil J. Hiley! He was the collaborator of David Bohm and his focus on noncommutative nonlocality is the key truth to reality (it's also the truth of nonwestern philosophy as mind-body transformation as Eddie Oshins realized when he coined "quantum psychology" working at SLAC).
I'm listening to this and my intuition is telling me that 'spooky action at a distance' is the same particle - it is vibrating in 4 dimensions (3 Space and 1 Time). It's the vibration in Time (both +/- or forward/ back) that makes the observation not obvious. When we observe 'two' entangled particles, we are seeing one end of the particle with different 3D Space coordinates to the other end of this vibrating particle, but both ends are observed at the same 1D Time coordinate. The whole 'action at a distance' makes sense with 4D vibrations. Which means the Wave Function is incomplete.
When we measure the above entangled particle, the Arrow of Time becomes significant in one Time direction with the collapse of the Wave Function. When one end of the particle provides a particular observation, the other end cannot be observed with the same property - like a pivoting mechanism on a 'see-saw'; up and down, positive and negative, north and south, spin up and spin down and on on. Information doesn't need to travel distance faster than sped of light because this isn't happening when we observe the same particle with the same Time coordinate but different Space coordinates.
The Wave Function being incomplete needs to be modified to account for the above. It's like our observations and explanations are missing 1 dimension...
Not saying this is you, but it's amazing how many people spontaneously solve the contradictions in quantum mechanics after watching a few TH-cam videos on the subject.
I couldn't help but wonder what you mean by the "other end" of a particle?
@@mylittleelectron6606 - Well, you never know who is leaving these comments. Personally, I studied Quantum Mechanics as an undergraduate over 30 years ago - so this isn't some first TH-cam video for me. To answer your question: The 'other end' of the single vibrating particle in 4D is the 'second' entangled particle being observed. Hope that makes sense.
@@mylittleelectron6606 It's still fun. Nothing wrong with entertaining amateur theories so long as we don't discard what professionals do. This theory was great. A really cool idea actually.
Still coming up with the ideas is the easy part, proving them is another story.
@@definitelynotcole Hey, I'm glad you enjoyed it!
That was one half, the other half completes the cycle at the opposite extreme: Consider taking the above entangled particle such that it approaches a black hole. The so-called Arrow of Time is broken as the entangled particle gets closer to its centre, where the 4D vibrations start to become more significant again in the Time dimension. The see-saw mechanism avoids the singularity at the centre of this black hole where the Time coordinate is so dominant that vibrations in the other 3D Space dimensions don't have a chance to form a singularity - the entangled particle appears in another Time. And so the cycle continues...
You can create a thought experiment with a double-slit experiment at these extreme systems where the scattering pattern occurs in 4D such that elements of the observed pattern occur in both the past AND future, predicted by the Wave Function modified to operate in 4D...
I hope you invite TIm Maudlin again there is a lot more to discuss
Timothy Nguyen is a great physicist.
also, just to make it a bit simple, the only requirement where neumann is right about what you mentioned, is about nodes with respect to amplitudes, any addition variable state described statistically by wave function must also never admit an outcome where the probability density is 0. that is is, the rest can be mucked around with by producing many different "micro quantum states" with specific outcomes, as long as the resulting distribution comes out right. and if you think about it, this is obvious, it is a property of all statistical physics, such as restrictions on energy for example, take a double pendulum in a superposition of classical initial conditions, none of them will evolve into a state where the energy has magically increased permanently, so with respect to the micro state phase space and the statistical description we have some node in phase space, where the probability density is 0, the dynamics are completely different but the principle is the same, none of the individual states of the pendulums involved in the evolving distribution can ever attain a larger energy than the initial value, that is a prerequisite, these kinds of constraints are all the constraints that is on producing a consistent statistical theory in general, apart from questions of special locality and so on.
I do not get it. What is wrong with the correlation being preset from the origin, like Bertelman's socks? It seems that QM just says nothing is predetermined until it happens. So why then do people think QM says that, and Bertelman rules?
I think there are two separate questions here but for correlations being always present there is a theory that holds that, it is called superdeterminism
A wavefunction says all its composite states are possible, but if they're not via correlation, then there's information the wavefunction is leaving out. The wavefunction alone cannot account for correlations, and the context is if there's more to the reality that quantum mechanics needs to address to be "complete".
Measurements on spin are over-correlated at in-between angles.
Your statement sounds contradictory.
Usually when people say "the correlation exists from the origin" they mean precisely that all the outcomes are predetermined. That is, there is something about the state of the system that tells you exactly what all the outcomes would be such that the required correlations are satisfied. It turns out that this is mathematically impossible for correlations as strong as those predicted by QM.
In what sense do you think the correlations could "exist" before the measurement if the outcome is not predetermined? That is how are the correlations encoded in a physical system without determining the outcome?
@@Anytus2007 When a measurement is made, some sort of communication needs to pass between the two entities at the spatially separated detectors. This communication has the nature of a one-time pad rather than a real message. I suggest that there is a natural Vernam cipher at work. I can think of two different types of VC.
This is what I don't get about quantum computers. They say they use entangled qubits to do the calculations. But when the state is read, entanglement is destroyed. But how do they set the state in the first place without destroying the entanglement because now they know the state.
And about those corrections that has to be done because quantum computers result in wildly wrong results (or multiple results which one might be the right one). If you already know how to correct the outcome, don't you know the outcome itself thus making quantum entanglement impossible, since you know the state already.
And then, how can the qubits be in high correlated state and the result be gazillion different probabilities if there is high correlation - exactly like the video explained deterministic v indeterministic problem leading to spooky actions.
I'm puzzled in so many ways not even qubit can comprehend it.
Preparation is the same as measurement. It doesn't destroy entanglement, it merely entangles the quantum system with the preparing/measuring system.
This is very good stuff! Thank you.
Why are we not focusing on the ontology of what spacetime is made of?😢
I've seen innumerable explanations but none that makes it as clear as this one.
Nice work, both of you. Yes? 💪
Tim this is a great episode. I've replayed parts of it. I still am not clear on the equality. Could you explain the cos formula (disagreement rate). Is this a quantum mechanical formula? Or observed experimentally? Or is it just non-quantum math? Thanks if you get a chance to explain.
QM implies the spin-correlation between Alice and Bob is -cos alpha (see Bell's original paper). If the disagreement rate (p_disagreement) is r, then the spin correlation is 1 * p_agreement + (-1) * p_disagreement = 1 * (1 - r) + (-1) * r = 1 - 2r. Hence -cos alpha = 1 - 2r. The next step in the insert at 1:44:17 is trigonometry.
I realize now the whiteboard uses alpha but the insert uses alpha/2. Oh well, the lowest insert indicated that we messed up factors of 2 during the live presentation so the reader is meant to know that they need to be inserted appropriately.
Ah. Got it. Thanks. @@TimothyNguyen
Given the example of a box of gas, reminds me of an assertion that was made regarding zero point energy systems. The energy contained in the space within a teacup is enough to boil off all the oceans on Earth. As far as I know, there is no criteria for the reality of how a zero point energy system works, but we know that there is potential for such a system to exist.
There is no such thing as "zero point energy" or "vacuum energy". That concept originates from a naive quantization of the physical vacuum. It's simply math gone bad.
I agree with what Tim is saying, i know very diplomatic and economical, two compliments in one, maybe complimentarity isn't so bad after all. What i would like to hear from him is the difference between locality as in a causal structure woth a finite speed limit, and more general definitions where there is no upper speed limit. The difference matters a lot for the argument when it comes to what experiements have to be done.
I love that he calls out Black Hole Entropy. Never understood all the hype with Hawking’s supposed deep discoveries.
The "hype" is that we made an enormous amount of progress in understanding the solution theory of Einstein's equations and the consequences they have at the thermodynamic level. It's an enormous amount of non-trivial mathematical work (and not just by Hawking but by a cast of hundreds, if not thousands).
"What Bell saw was that from their premises EPR provide a perfectly good argument...if you accept the locality assumption that's implicit in EPR you have to accept their conclusion; which is that quantum mechanics is incomplete."
Through out my life I was told Bell proved Einstein's hidden variable theory wrong and proved Bohr was right, how wrong could you get, both were wrong and Bell showed the universe was non-local.
Did you see that bullshit on the internet or are you just playing a game of telephone? At most it was said that the world is not locally real, but that does not mean non-local. That all physics is perfectly local follows directly from special relativity. If the world wasn't local, then your iPhone would have an ansible built in, but on the downside the universe wouldn't even exist. ;-)
Neither Bell nor anyone else has shown that. Tim Maudlin is a crank who's become notorious for pushing that quantum foundations illiterate falsehood (and one or two others). There's an excellent refutation of it by Werner in J. Phys. A. DOI 10.1088/1751-8113/47/42/424011
Point being, if you allow for faster than light interactions you can infact still have a local and deterministic theory. Without being conspiratorial, and without contradicting experimental results.
The thing is that quantum mechanics would predict that even for all definitions of simultaneous measurements you would see the same violation, that however has not been tested, and cannot be tested in such a way to confirm the quantum mechanical prediction fully, you can only contradict quantum mechanics for a finite experiment, that means that if you wanted to rule out the violation of quantum mechanics, you would need to do an impossible experiment, only the lorentz symmetry violating result can be attained in a viable experimental setup. The null result for the violation of quantum mechanical predictions, or more generally the same violation of bell for all definitions of simultaneous measurements, is sort of a passive result that you cannot ever fully test, because there is an infinite number of simultaneous measurements you would have to do, to rule out the lorentz symmetry breaking result fully.
at 1:26:46 does the spooky action happen before or after R3
Why does it have to be odd at min 1:55:30?
So how do particles actually get entangled and how do we know that their not "partially entangled"?
Also note that even if Bob can know the momentum of Alice's particle as soon as he makes his measurement, ALICE CAN'T. She still has to use the superposition of possible momentum values for her own work. That cannot change until there has been time for information to arrive from Bob.
Why not call the “hidden variable” an omitted variable? That’s what we call it in statistics when a variable isn’t included in a model but it could have some sort of bias that is unknown and not accounted for.
Why not call Santa Claus "bearded redling"? Would renaming make Santa any more real? ;-)
There are no hidden variables and it's intuitively extremely easy to see why there can't be any.
@ I literally just suggested to call them something that does not mean hidden. Omitted means left out in this context, which is exactly what the content of this video suggests. It’s so “intuitively extremely easy” to see that.
@@jbj926 And I just suggested to call something that doesn't exist "something that doesn't exist". ;-)
What does it mean: nobody understand? Does it mean that its different from daily experience or you do not know how to use it?
I didn't get how 30 degrees equates to 25% disagreement(or 60 degrees or whatever it was supposed to be) That would imply 100% was 120 degrees(or 240), it doesn't seem to fit with the reality of the spin test.
It seems to me QED is fairly easily understood if we consider photons to be solitons in the EM field.
The situation with QCD is much more complex but it wouldn't surprise me if solitons were also lurking in there somewhere.
Making rational statements, making well-founded statements starting from a given context, is very difficult. Luckily, Mr. Maudlin got to a position and rank in analysing discourse and in being acknowledged where he can make radical statements about the current state of scientific knowledge.
Tim Maudlin is a hero.
Only in the minds of people who don't understand physics. ;-)
@ oh really Mr Einstein, you’re saying Maudlin doesn’t understand physics, oh ok I’ll gonna believe you over him, yeah, yes, what a genius you are
@@eddymoretti3742 Physics is not a he-said-she-said, kid. YOU have to understand NATURE. Which you don't. Now let me give you some more attention until your Mom comes home and feeds you dinner. ;-)
There’s more than one way to travel faster than light. We can have an oscillation in one of the ways which leads to destructive interference, and tachyonic Brownian motion in the other way which leads to broken symmetries between detectors. The entity I have described is definitely both a wave and a particle. Whether it is the same as the typical entity found in quantum mechanics remains to be seen, but the claim that nobody understands quantum mechanics could actually be wrong.
The catch is that any computer simulation of the collapse of the wave function based upon this idea may need to model many dimensions of configuration space, or in other words may need to run in exponential time.
I disagree with Tim Maudlin here. I don't see any way the world can be nonlocal based on our current understanding of it. We have modern physics with its effective field theories, specifically quantum field theory which is eminently local. It's Lorentz covariant, by construction. Traditional quantum mechanics itself is not AS local because it's non-relativistic, but it's still more local than people realise. In fact, the only really ''nonlocal'' aspect of traditional quantum theory is the collapse of the wavefunction, but the vast majority of people in the field don't think that is something that actually occurs. Even Bell's Theorem doesn't necessarily imply nonlocality, as long as you don't think there is a wavefunction collapse happening. I mean, if you look at some of these so-called interpretations of quantum mechanics (including the Bohmian one Maudlin seems to be fond of), a lot of them start from the non-relativistic domain and then try to build a story from there, which in my eyes is just not the way to go. In my opinion, we ought to start from what our most well-established theories, such as QFT, tell us and then try to paint a metaphysical picture of the world if we can, not vice versa.
QFT is cheap. “Local” means that objects can be influenced only by their surroundings and that any influence cannot travel faster than light. The question/topic is not as you pose it "I don't see any way the world can be not local". It's not important whether you can see a way the world is not local. Everyone can see a way, they just need to fantasise a bit. The question is not whether we CAN see a way, but is this: DOES anything happen at the microscopic scale which shows that IT IS TRUE that---- objects can be influenced by outside of their surroundings, or (does anything show IT IS TRUE that) influences DO travel faster than light? That is the question. The answer was No in 1920, it was still No in 1950, still no in 2000, still no today in 2024. Nothing that happens at the quantum scale, nothing we have EVER observed to happen, SHOWS those things are in fact true. It's that simple.
As for QFT--- yes, cheap. We are waiting for an actual theory that explains the phenomena we observe at this scale. Including Heisenberg's Uncertainty Principle (which can be regarded as driving all these phenomena into existence). We are waiting for an explanation. A theory. You know, physics? That's what physics involves -- Explaining (and describing) phenomena we observe in our world. Just like--- we were waiting for someone to explain the motions of bodies in deep space (thank you Einstein, for spending 10 years of your life, to nail that down, where nobody (prior to you), could fathom the mechanism) we are waiting (again) for an Einstein--- because we again are facing strange phenomena that needs explaining AND--- we don't like cheap (qft). That's not an explanation for the phenomena we observe. It's not a theory. It does not reveal why we need to be using wave math (of all things) to predict the chances of finding a particle here, or there. It does not explain--- what is going on behind the curtain. to make these effects be. It's kind of like had Einstein not explained gravity at all, and on year1 (instead of on his year10) he just said "Oh there are these fields around the earth...they just act on the moon and Make it move toward the earth, there is nothing being transmitted from earth to moon!". Anyone could have said that, back to Newton. But they didn't because it's cheap, incomplete. that's QFT. It's as weak as blaming god.
I will however say that QFT is a bit less laughable than Pilot wave (which, the latter, a bit less laughable than Many worlds). So you've got that going I guess, but outside of being compared to crap attempts at making sense of QM, it is trash as a theory. We are waiting for an Einstein. For a proper theory that explains exactly what is going on -- what makes sensible -- the observed phenomena at this scale (just as he provided that sensibility for the macro scale).
As for your Wave func? Obviously there is a wave function collapse. We stop using the math (the wave function) when it stops having applicability, such as when we measure the value of particle (eg, position, or spin). The math collapses, but that's just a poetic way of speaking. I have a mathematical function here which describes how this dime spins on a table over time while subject to gravity. But when Amy comes into the room and knocks the dime over so she can read the date on it, my spin-function collapsed, and I don't have any trouble explaining how this happened. Nor do I deny that it happened. My spin-function collapsed. Yes, that's what wave-function collapse means. It means there is (at once) no applicability anymore, because the conditions are no longer to which the function applies. Not a big deal. Trivial.
Those who claim that the wave-func is something MORE than the mathematics we are here using to make predictions, need to specify what this mysterious thing is, where it is, and most importantly-- HOW THEY FOUND OUT that thing exists? Where is the evidence of this thing's existence? Isn't that important? To know that it exists--- before going around claiming spiritual nonsense like OMG THAT THING collapsed just now!! What is this, philosophy? Poetry? Novel making? This is physics --- They owe to explain WHAT it is and HOW they found out that it in fact exists, before they go talking about things it does like collapses. Make them act like a physicist (less like a philosopher, or Deepak Chopra) and you'll see that they have nothing. Out goes the collapse problem. Back it goes simply to "math applies, or not applies". Back it goes to--- waiting for an Einstein to explain phenomena at this scale, which our mathematics is working to describe (for some reason only the theory knows).
@@TimoBlacks I don't think you know what you're on about, pal.
@@Al-ji4gd lol, on something that upsets you, i know. cause you're weird, I've seen your comments.
good luck with the cheap interp :)
@@TimoBlacks So weird
@@Al-ji4gd yes you are ;) i see that that shmetterling guy upsets you too lol.
Anyone else find the ego quite visible ever since the blow-up with Kastrupp on TOE? Didn't really notice it before, now it seems quite obvious in hindsight.
A) Isn't, "faster than light" outside of time or rather timespace?
B) Quantum mechanics to me seems to be so extensive that it requires specialists in different areas. No one understands it completely but you could have the people that do, all in one room at one table.
You can derive the basics of quantum mechanics in a few dozen pages. It doesn't require any specialists. It's one of the most simple theories in physics. The applications of quantum mechanics do, of course, fill libraries. What Tim Maudlin is talking about here, however, is one of the most trivial aspects of the theory... he just doesn't seem to understand it.
What, precisely, is a "causally local thereom"?
A theory where the causes are all in the experiments past light cone
I always thought all of this was obvious to people, but i learned over time that people are very very confused even if they know perfectly well how to calculate in mikowsky space. Even when i was in high school the teacher who had a degree didn't understand that you could start in any reference frame and talk about all the effects as coming from velocity with respect to the background you chose, and the answer would turn out the same. Took me about 5 minutes to spot that the first time i ever looked at relativity, then when someone tries to tell you that your intuition is wrong it is kind of distressing that they are wrong and have a degree. Just take the twin paradox, the proper time always works out in the same ratio no matter what background you start with in euclidean space, where time dilation is "objective". And the same kind of thing applies just the same to length contraction, the only problem with this kind of view is when you change points of view along the way without accounting for the accelerated reference frame. I have had quite enough of people believing in principles they don't understand, especially when the principles are right, the problem is that in mamy cases the principles are stated in a form where it just reifies a certain representation and then people say "everything is relative" and they happily forget they don't understand what that means in all the resperentations of the theory they believe in. Or maybe some even say "there is no universal clock" or something silly like that, which os absolutely not true at all, everyone always agrees about every one elses light cones, and everyone elses definitions of time, there isn't just one universal time, but as long as lorentz symmetry is there and the causal structure is a light cone structure then there are "infinite universal clocks" using any one of them is perfectly fine.
Yeah, I frequently see the claim that QM is some ineffable mindfuck while relativity is relatively (see what I did there) simple and easy to understand but at least the interpretational difficulties inherent to quantum theory are acknowledged, analyzed and delimited by those who care about such things, while highly questionable claims about what relativity really means, that stem from confusing observation with reality, are accepted by the scientific establishment as proven dogma, like what you point out about time.
If you search for "light compass" on here you'll find a guy trying to dispell the widespread misconceptions about what relativity means which I think you'll like, though it is sad that is where you have to go for such a thing.
What is being measured in QM? Probability. Probability of what tho? Probability of a measurement?
In quantum mechanics we are measuring energy, momentum, angular momentum and charges. We can repeat many such measurements and then arrive at frequencies. We can never measure probabilities. That would require an infinite number of measurements.
@@lepidoptera9337 is probability distribution is the only we can observe tho? We posit the wave (function)? We can measure this or that and then cross reference data to see axiomatic nature but then things get weird.
I'm dumb tho. Still trying to PhDs like Maudlin. I don't understand MW theories.
@@Micheal313 One can never observe a probability distribution. Those are abstracts, similar to the real numbers. One can only observe finite frequencies. There is nothing weird here. Quantum mechanics can be derived from the same assumptions as probability theory: that individual samples/experiments from a random sample set/physical ensemble are statistically independent. These assumptions are usually called Kolmogorov's axioms. Why are individual quantum mechanical measurements independent? Because of special relativity. The only "weirdness" here is the fact that we don't teach these trivialities either at the high school or the university level and so everybody and their grandmother's dog is suffering from DK about this. Folks just don't know what they don't know (even though all of this can be found in papers in the physics library) and they keep talking about their lack of education like as if it was a fact of nature. It isn't. All you have to do is to read the primary literature on the subject to understand what is going on. It's rather simple stuff that doesn't require anything beyond high school level algebra to understand.
@@lepidoptera9337fair enough but can you expand on how special relativity makes QM measurements independent? I appreciate this all thx. I prefer to hear real peoples perspectives over mainstream.
I really don't understand what statistical significance independent is because aren't they dependent on a device for measurement?
@@Micheal313 All the events that can influence a local observer are inside the observer's backwards light cone. All the events that can influence the observer's future are in a light cone that contains more volume than the present one. The extra volume consists of spacelike separated events that are currently unknowable.
Let's make an example. One of our Mars probes has a radiation detector on board. That instrument measures a sudden burst of radiation RIGHT NOW (in our local clock time here on Earth). It triggers the radio of the probe and the signal is now on its way to Earth. This will take roughly ten minutes, during which time we have no way of telling what has happened. Our future, ten minutes from now, will therefor be influenced by a completely unpredictable event. That is the source of uncertainty in quantum mechanics.
This rather simple effect does, of course, not show up anywhere if we are only looking at non-relativistic quantum mechanics, which is how we usually teach QM in introductory classes. This is simply an artefact of our educational system which starts with a toy system that is, indeed, not "complete". The fully relativistic theory, OTOH, doesn't have this problem. It just happens to be much, much, much more complicated in mathematical terms.
If you look carefully the two situations are not the same, different experiments apply, to test the same inequality, because of what i said, for superluminal action at a distance you don't have the luxury of just considering any old timing that is outside the lightcones, you have to check individual surfaces of simultaneity.
I really don't see why there's a problem with giving up statistical independence, we are dealing with elementary particles not people. The results depend on what you measure and yeah perhaps the conclusion is that we may not be able to apply the scientific method at that scale anymore because the system cannot be measured without disturbing it. We could try a few experiments before giving up on that though.
49:00 - ALICE'S PARTICLE DOES NOT HAVE A STATE TO AFFECT REMOTELY. Only the system of both particles has a state. And that state does not exist in physical space. So speed of influence doesn't even make sense to talk about.