When particle single photon released, how does observer device captures ? Photon speed is speed of light??? Observer device shoots another photon, To detect photon? When photon when not observed is it in wave form because of quantum gravity? When observed its gravity changes and hence particle?
@@priyakulkarni9583 Yeah that's what Roger Penrose says. When the superposition/wave is "too heavy", the spacetime curvature it creates shrinks it into a dot-like particle.
Loved the video, especially the part where you debunked the misconception that superposition is NOT the same thing as being at multiple locations at the same time. But, on a similar line, saying ‘electron goes through both slits’ is also a gross over simplification! Infact if you use any words to explain what the electron is doing, we will end with a misconception. And so I think the most accurate way to think about it is that the electrons are not going through either of the slits. They are not going through both. They are also not going through neither. This exhausts all the possibilities we can think of and yet, the electron is doing something involving both slits. And that something is termed a quantum superposition. And that’s that. You can’t articulate what quantum superposition is using any language (except math). You can only ever tell what it is not!
Indeed, superposition is our inference about experimental results, rather than a phenomenon that can be directly confirmed through experiments. There is no experiment that can prove superposition, or show that a quantum particle can simultaneously pass through two slits, or that superposition is canceled upon detection. These are all imprecise statements with no experimental evidence to support them.
That's true Mahesh, but you know as well as he does that it's always a compromise between clarity and accuracy. In fact, this is the first time i've seen anyone show a more accurate depiction of what the probability cloud actually looks like going toward the slits. He just closed up a glaring omission in almost every video i've ever seen. Of course it's true that, as the Buddhists say, the moment you open your mouth, you're off target, but they still have a great deal of literature that i'm quite grateful for. And speaking of Koans, nobody has ever addressed the stern-gerlach paradox. Maybe you should do a talk about that.
I think people should read Schrodinger's book _"Nature and the Greek and Science and Humanism."_ Schrodinger had originally argued for using the wave function to replace Heisenberg's original formulation of QM where particles don't have real states between interactions and only have real states in the moment of interaction. Schrodinger hated this, saying "I do not believe the electron hops about like a flea." However, Schrodinger realized that introducing the wave function to fill in the "gaps" between interactions just introduces a new "gap" between the continuously evolving wave and its "collapse" upon measurement, and thus in that book Schrodinger argues in favor of returning to the Heisenberg picture. QM is far more intuitive if you treat it like this and all the "paradoxes" have simple explanations. The only thing that is _real_ is the particle's state during an interaction, there is no _reality_ of it in between interactions. If you accept this one premise then the rest of quantum mechanics follows without introducing a fundamental role for measurement, spooky action at a distance (nonlocality), particles being in two states at once, collapsing wave functions, a multiverse, some sort of special role for the conscious observer, so on and so forth. All of QM follows from just one principle that reality is made up of events and not autonomous objects and that objects "hop about like a flea" between interactions predictable by mathematical laws.
Thanks, that answers a question I've been having for a few years. I've had a working knowledge of QM at about the level of this video for decades. I did not realize there was a "measurement problem" until I started watching RUclips physics video's. What problem? I just didn't get it (I still don't). If you assume a particle to exist as something like a probability wave, isn't what the experiments show exactly what you'd expect to see? Why are we not done here?
"The only thing that is real is the particle's state during an interaction, there is *no* reality of it *in between* interactions." Hmmmm... what if the interaction is "on" all the time? like between electrons in a heavy atom? or constituents of a solid?
@@GeoffryGifari those electrons would be interacting as probability waves and then you’d still need to measure them to figure out their state forcing them to be localized and collapsing the wave function, so the problem is the same.
@@salahlamsaoub7753 hmmm but at what point does interaction between subsystems count as a measurement? why can't we say that electrons in an atom measure each other? how big/separated should a system be until interaction counts as measurement?
So basically, we don’t know exactly where the particle actually is before we measure it, so we came up with a mathematical formula that expresses this “where it might be” as a probability wave. We can say the same thing about tomorrow’s weather. There is a 30% chance it might rain, or a 70% chance of being a sunny day. Until it actually happens, we don’t know for sure, so we use a probability to describe it. When we do measure the electron, of course then we know where it actually is, so the probability prediction is no longer applicable after that. The mind bender is that, the double slit experiment proves that this probability wave that we made up IS actually happening in reality before we measure the particle.😮
Thanks for the video. I usually watch your videos and really enjoy them, but for this video I have a couple of comments: 1. A measurement is NOT just an interaction. Inside a solid numerous electrons that are in superposition are interacting, but none is measured. Also two hydrogen atoms interacting with Van der Walles force are not being measured, but they still interact. In fact, there is no equation showing what a measurement is (there is no equation describing wavefunction collapse). 2. If you take Schrödinger’s equation seriously, meaning that you take it as really describing reality, then a superposition is the existence of “multiple histories” of the particle. Once it interacts with a macroscopic measurement apparatus, each part of its superposition becomes entangled to it and to its numerous degrees of freedom, generating a practically random phase to its part of the superposition. Once you make many experiments with superposition states that have random phases between them, they no longer interfere with each other (decoherence). In some way all the measurement possible outcomes co-exist but they can no longer interfere with each other. But again, this is if you take the Schrödinger equation seriously and not merely as a calculation tool only. 3. The wavefunction being a complex number has nothing to do with it being non-physical. In fact, one can formulate quantum mechanics without complex numbers, it will just be very cumbersome. Furthermore, even a pendulum amplitude and phase can be described with complex numbers, and it surely is physical. In summary, all while one ignores the measurement part and treats it like magic, then one gets to failed and inconsistent interpretations.
For your first point. In video it is said that measurement is an interaction, it doesn't imply, that all interactions are measurements. For example, in double slit experiment you can measure a particle on the slits with light. It will break interference picture, as mentioned in video. But ONLY if light's wavelength is actually less than the distance between slits, so that you can certainly find out through which slit the particle have passed. Otherwise the interference picture would not be broken.
@@sn3232 What needs to happen at the slits is entanglement between multiple degrees of freedom. Amplifying that entangled state and collapsing it is a measurement. It's the collapse we don't fully understand. You are correct that it is possible to have interaction without measurement.
I'm not a scientists, just someone interested in the strange world of quantum mechanics. Over the past 30+ years I have read many, many books on the topic written by reputable scientists and authors. You have essentially summarized all of them in this video. Outstanding. You've managed to lay out the problem piece by piece in layman terms without sacrificing some technical areas. But I have a question. You talk about the electron wave approaching the double slit and when it hits the screen we know its location. What is the electron when it is fired toward the screen? Is it a particle that turns into the wave? How do we send electrons to the screen and do they start as particles or waves? It's like the story of the little boy walking down the street holding a burning candle. A wise man approaches the boy and wishing to teach him a deep lesson and make him think, he blows out the candle and asks the boy, "Young man, where did the flame go?" The young boy thinks about it then replies, "You tell me where it came from and I'll tell you where it went."
In your example there are two instances where the position of the electron is known: when it is emitted, and when it hits the screen. Both of those can be considered interactions (or observations.) At both those instances the electron acts like a particle. In between those instances you are not interacting with the particle, so it is acting like a wave. It is in between interactions that an object acts like a wave, and it is at the point of interaction that it acts like a particle. There can be many interactions in the lifetime of an object (say, an electron), so it can alternate between the wave and particle behavior many times.
What I got out of this video is that the electron in its wave state is energy organized a certain way in a particular area. When in this state, it has continuous energy level (amplitude) changes throughout the 3d volume that this electron exists in, thus called a wave. I'm guessing that it is an active, projected energy in the realm that we live in and can perceive to an extent, and was latent ( or maybe active) in another realm that we do not understand, before it was projected. The device with the cathode was what projected this latent energy into our realm that we perceive and live in. Also, perhaps the electron quantum field is an energy field that is organized in a way so that it acts as a mechanism that is a kind of aperture between both realms. or maybe this latent energy is part of the electron field itself. Or, maybe this latent energy induces latent energy of the electron field to become active. The electron wave comes into our realm by means of the quantum electron field mechanism. When it interacts with a photonic device, such as a flourescent screen, the interaction changes the electron wave's organization in a way so as to cause a particle effect on the device, which, maybe, could be called a further induced manifestion.
Imagine this. You are in complete blackness with nothing around you. A light emerges behind you, shining in all directions. But we aren’t looking at it. It is there, particles of light, traveling in waves. But we don’t see any of it. The reason is that we need the photon to interact with our retina in order to observe it. The eye is a directional antenna tuned to the EM energy we call light waves. When the photons bounce, reflect, off of something in front of us, or if we turn to look, we see it is there. It always was. The photon has to hit the retina. This next is not a great example of quantum but illustrates the mental concept of superposition and interaction. We are bathed in local radio waves from radio stations. As long as we don’t tune in to it, (observe) we do not know it’s even there. It is said to be in a superposition. (Bad example again) But when we tune into it, we interact with it. We observe it. The thing is, other observers from other locations can observe the same field. Light or radio. The field does not collapse through observation. We simply grab one particle. And when we launch it. It can only move in it’s wave form. The frequency of it.
Lay man here But let me explain what I understand on the subject An electron is a small packet of energy in a tiny volume of 0 dimensions. So small you can't measure it's volume. You know its exact location when you are firing it, and you know it's location when it hits the screen. It between you don't know it's location. The electron is not a wave in between, but the information of it's location is a probability, and the wave pattern is directly related to this undeterministic property of it's location. This is very unintuitive but a law of nature due to Heisenberg uncertainty principle. Other than that we don't know much about the exact shapes, forms of quantum objects. Are they waves themselves in that infinitesimally small volumes? Maybe, string theory postulates them to be wiggling objects, like a wave. But string theory is mostly a dead end, some other theory in the future might still prove them to be waves themselves well. This is a short summary of what my limited understanding of quantum physics. I could elaborate some more but not much more, due to limits of what I know.
“The math of quantum mechanics does not describe the universe.” All the mysticism surrounding QM disappeared for me when I realized that we have no math, no physics at all, to describes the unobserved quantum world. The wave function and the Schrödinger Equation only describe the classical view of things.
I don't think nature has that dismissive quality than humans have sometimes. I just think it is shy and doesn't offer up information about how it works easily.
Particles before measurement exist in a future state. Because causality has a speed limit (c) every point in space where one observes it from will be the closest to the present moment. When one looks out into the universe they see the past which is made of particles (GR). When one tries to measure the position of a particle they are observing smaller distances and getting closer to the present moment (QM). The wave property of particles appears when we start trying to predict the future of that particle. A particle that has not had an interaction exists in a future state. It is a probability wave because the future is probabilistic. Wave function collapse is what we perceive as the present moment and is what divides the past from the future. GR is making measurements in the observed past and therefore, predictable. It can predict the future but only from information collected from the past. QM is attempting to make measurements of the unobserved future and therefore, unpredictable. Only once a particle interacts with the present moment does it become predictable. This is an observational interpretation of the mathematics we currently use based on the limited perspective we have with the experiments we choose to observe the universe with.
I think people should read Schrodinger's book _"Nature and the Greek and Science and Humanism."_ Schrodinger had originally argued for using the wave function to replace Heisenberg's original formulation of QM where particles don't have real states between interactions and only have real states in the moment of interaction. Schrodinger hated this, saying "I do not believe the electron hops about like a flea." However, Schrodinger realized that introducing the wave function to fill in the "gaps" between interactions just introduces a new "gap" between the continuously evolving wave and its "collapse" upon measurement, and thus in that book Schrodinger argues in favor of returning to the Heisenberg picture. QM is far more intuitive if you treat it like this and all the "paradoxes" have simple explanations. The only thing that is _real_ is the particle's state during an interaction, there is no _reality_ of it in between interactions. If you accept this one premise then the rest of quantum mechanics follows without introducing a fundamental role for measurement, spooky action at a distance (nonlocality), particles being in two states at once, collapsing wave functions, a multiverse, some sort of special role for the conscious observer, so on and so forth. All of QM follows from just one principle that reality is made up of events and not autonomous objects and that objects "hop about like a flea" between interactions predictable by mathematical laws.
This is very interesting and I'm glad you posted it. I'm still trying to fully wrap my head around this viewpoint. There are major questions that are asked by this, such as, what does this imply about gravity and the other forces? This seems to imply an inherent asymmetry between the future and the past which may be fundamental or consequential. Can we then talk about forces moving things from past to future or vice versa? Gravity is an effect in the past acting on the present I suppose. But the quantum forces, would we say they act in the future or the present? And which direction do they tend if any? And is this an absolute future or a relative future? If I measure a particle in the present, does that destroy its quantum properties for other observers?
@@Thomas-gk42 The measurement [problem isn't a problem in the world, its a problem in people's heads, and has been solved in more than one way, decoherence, entanglement, etc. What it does mean is to stop arguing philosophy and to start doing science.
@@ozzymandius666 Stop doing philosophy and start doing science is a good slogan, but the measurement problem is an inconsitency that needs to be solved in science, not in philosophy. It means, that we don´t understand what physically happens in the measurement process. To understand it, could bring progress in science and technology.
@@Thomas-gk42 but there is the possibility that there is nothing to solve at all. You can debate this. It does not mean that you should not try to solve it, but it may be worth to prove that it can't be solved, similar to Godel's incompleteness theorem in mathematics.
@@rutger4131 I agree, but if we have the possibility to observe the gravitational field of more and more massive objects, we should do that instead of the thousandth Bell-like experiment.
2:01 "Multiple states at the same time" Yes, a Gross simplification. Superposition has always disturbed me till now, and I hate how widely the information is spread.. And also, "The math of quantum physics doesn't describe the math of the universe, it describes what we'd get if we made a measurement" ❤ Thanks for the beautiful line, Arwin Ash. I also approve your statement because it is just to simplify our caluclations.. Also, a big thanks for the animation for the 3D probability density of the electron through the double slit! I really wanted it 😄
As a photographer I’ve always felt it’s easiest to picture measuring quantum particles as akin to cranking up the shutter speed to capture a fast moving object, but now it’s stationary, you know precisely where it is but you can’t tell any motion apart, and as such you no longer know where it’s going, you could crank down the shutter speed somewhat and still get some motion blur, but it wouldn’t give you all the info on motion. Maybe it’s similar to this principle but the breakdown between the two happens over a much narrower range with quantum particles.
Not a bad analogy. The observer wave synchronizes with the observed wave so it appears solid, like the props on a movie can appear still when synced to the frame rate. But they are ALWAYS ONLY waves, particles are a figment of our reaction time..
Instead of firing through 2 parallel slits, I may suggest experimenting with firing at an "X", or "XX" crossed slits to test for chirality or supplemental effects.
A police officer pulled over Heisenberg, and asked “Do you have any idea how fast you were going?" Heisenberg re[lied, “No but I know precisely where I am.” The cop says “You were doing eighty miles an hour.” “Oh great!” says Heisenberg. “Now I’m lost!”
QM works within it's own context. It's a description of a limited range of phenomena. It's a placeholder waiting for a finished theory of everything. We use QM because we're not gods.
Thanks for clarifying the "superposition" meaning. Intuitively, superposition defined as existing in multiple places at the same time seemed very wrong.
I suggest that whatever the electron is doing (or what it "looks like") as it moves between the double-slitted wall and that of the phosphorescent screen is the closest we can come to understanding what an actual Kantian "noumenon" is all about. In other words, it is something that is "real," but can only be imagined and never directly perceived.
The critical issue is the question, "What is a particle?" Arvine Ash correctly highlights that the mathematics of Quantum Mechanics focuses on detection rather than the particle itself. In this context, a "particle" is the portion of a wave that we can measure. The distinction between classical and quantum waves lies in how they can be observed. With classical waves, you can assess the entire wave-its height and length-by observing it along the beach. In quantum mechanics, however, you can only pinpoint the "particle" (or measurement) at a specific point on the beach. Note * that doesn't mean, the wave disappeared during the measurement, it means we can only interact with the wave at one point.
You can actually measure "quantum wave" at any point, that's what screen in double slit experiment does. The difference with "classical" wave is that the measurement is such a strong interaction it actually changes the state. Thus it can only be detected once and during this detection it is changed by the interaction. That's quite contrary to what you wrote, that "wave doesn't disappear".
@rickfrombohemia9550 If you take a snapshot of a classical wave you would see the whole wave on the picture. With "quantum wave" you would see only one particle in a specific place, this is shown on 3:50, except for the part, that "wavy thing" on the video is not detectable. To reconstruct the wave you would have to repeat the experiment many times, taking many snapshots. If you then put the dots, representing a particle on the same picture, you will see, that some positions are more probable. That's why it's sometimes called "probability wave". The process is shown on 6:53. PS: This video is only concerned with quantum mechanics, which operates with particles, and does not say anything about their nature. Notion of a particle as a quantum field excitation is coming from quantum field theory, which is a different discipline.
@@sn3232 Maybe a particle can be in more places at the same time, but since it's actually a quantum object, it means something different and more abstract than in our classical world. We just don't know how much different I guess. We can't imagine it, just describe it mathematically.
@@sn3232 I am trying to distinguish between what we know and what remains uncertain. We do not know if there is a round ball or "particle" in the traditional sense. In fact, I doubt the existence of any round ball; it seems more like a point where two fields interact and exchange energy. What we do know is that there is an energy exchange occurring at a tiny point within the detector. Moreover, when we sum up these energy exchanges, the overall behavior resembles a wave. However, this is unlike any "classical" wave we've encountered. While this doesn’t rule out the possibility of it being a wave, it suggests that it's unlike anything we've experienced with our senses. Could this be a "fourth-dimensional" or higher-dimensional wave within the fabric of space-time? We don't know for sure, but it seems plausible and potentially testable.
I'm thinking that probably what's going on can best be thought of in terms of quantum field theory. There is no particle but rather a peak in the field in a given area, like how a wave in the water has a highest point. The wave, with a peak as all waves have, isn't isolated but rather spread out over a given amount of space, and constantly moving around at high speed. So when the measurement is made we are simply seeing the highest point of the peak, wherever it is in that instant, and the interaction of taking the measurement has a flattening effect on the rest of the wave so we just see it as a point. So I'm thinking the supposed particle/wave duality is really just a contradiction created by our perception. There is no particle, it's all just waves, and we just label the highest peak of the wave as a particle since it has a definite position once we destroy the rest of the wave by the interaction of measuring. But I'm no particle physicist and I'm basically just talking out of my arse here lol.
The statement at 7:14, "this can only happen if the electron goes through both slits at the same time and interferes with itself"' Presents a solid conclusion about a phenomenon that still puzzles us, or in fact is unknown.
no. watch an actual simulation of a quantum particle and it will be self-evident how this happens -- the wavefunction or wavepacket indeed behaves like a wave.
@@rickfrombohemia9550 what do you mean you can't know what it really is? you mean you can't relate it directly to something you're already familiar with? have you seen the simulations? that is what it really is, it is what the mathematical equation is modeling.
@rickfrombohemia9550 it seems a little beyond the physical little instead of blatant interaction it appears to be "behind" regular matter like a deeper layer and beyond the 4th dimension
All you need is entropy. Plank time is the universe's SLA on processing entropy transactions, which need to be registered. While I used to think in terms of interactions, or changes in the possibility space, Im realizing that observer interactions need to lead to a change in entropy, which sorta commits the universe state to memory - entropy is one-way - but if that doesnt occur, the universe can keep the threads running in parallel, and you get double slit patterns. I engineer. I often use the thought experiment: the universe has some constraints, and seemingly never halted. Relativity and time dilation are a great way to prevent too many interactions from happening at once. Keeping with the exercise of being in the developer's head, without truly unlimited resources, Id want to use parallel threads and limit state updates as much as possible, and if there's no point, why bother. Well, there needs to be a quick way to determine if an interaction needs to be evaluated, and the singular one-way, 'if not null,' is entropy. If there is any change in entropy, it becomes fundamentally causal, but by definition, an interaction is fungible if there isnt a entropy change in the system => superposition/wavefunction thread, entropy affecting interaction == waveThread.join(main)
What's important to understand is that the dimensions of the slit matter when single electrons are fired through the slits to get visible proof of superposition, which then resolves itself into a single particle at the scintillator screen
I agree. That's a decent explanation. I've been saying pretty much the same thing for years and it's refreshing to hear a practical classical explanation. Something you may not realize is that quantum bits in superposition are hidden local variables. And a correlation of measurement by Alice and Bob can never be over 2 in reality. The violations of bells inequalities those experiments are nonsensical once you boil down to the basics. The take correlations over many instances to get to 2.8, which doesn't actually exist in reality.
Arvin Thank you for these great videos. Much appreciated. Please do a video on the technology and method used to measure these particles. They say, “see.” How do you “see?” Thanks
The superposition is the quantum version of "known unknowns". We don't know where it is, only where it can be. All knowledge is approximate knowledge. If no less invaluable.
If I were to summarize the video: we don’t know what particules are or where they are before we interact with them, we can only calculate the probability of their location.
it's okay it is explained confusingly anyway, like he keeps showing particles prior to measurement, and also shows waves made of particles? like dude, we have real simulations showing what the actual wavefunction looks like, be it one particle or many...
To make things easy I usually tell people that, try to think as particles not existing until they have to. The wave before a particle is a wave of probability for potential particles that will come into reality when it's forced to. Even if this may not be how it really works, no one really knows yet, it's a good start to understand the weird implications of Quantum Mechanics.
@@karlkarlsson9126 But how can potential/"unreal" interact with actual/"real"? Doesn't it have to be actual in the first place in order to interact (i.e. exchange energy)? If it is indeed potential, shouldn't we use different term than interaction?
My personal answer before watching the video: Superpositioned particles don't look like anything,as looking at them is measuring them, thus breaking the superposition
Nice! Great explanation of something that is usually poorly presented. A bit like you've measured the probability wave of bad RUclips quantum physics clips and resolved it to a single point 😂
Isn't the Schrodinger equation just a function of space-time. You can think of space-time as a liquid and the particle as a bubble. Fire that bubble at the slits, it splits apart forming two bublets, which interfere with each other on the other side and so form the interference pattern. Job done!
There was a form of the double-slit experiment where they used positrons as well as electrons, and showed that they could interfere without annihilating.
It is simple, it is just rendering. No multiple locations. Most of the scientists are desperate to find material but there isn't. It is just information within a ruleset.
In fact, as a result of the measurement of a quantum system, irreversible changes occur in the state of the measuring device, which we can read and interprete them for the translation into specific values of states of the measured quantum system.
I commend your effort and how you keep coming back to this subject. I have some notes, see below. I look forward to the next revision ;) 2:15: Whether or not you ascribe physical reality to the wave function (ontic) or that it only describes observations (epistemic) is (at the moment) an interpretational / philosophical issue. Both are valid (though you may disagree passionately with one or the other). 6:43 It is not just the electron which is described by the wave function. The wave function describes the entire experimental setup. Because most of the setup is macroscopic, we can describe the experiment for the most part with just a small portion of the total wavefunction. But you should not forget that in reality, the wave function is much bigger than the single particle approximation. There may be the misconception that each particle has it's own wavefunction. This is not so. A system with two, three, a million particles is described by one single wave function. That's one of the reasons why these animations never work out to create a true quantum picture. A measurement is (at least partially) amplified entanglement (amplified to macroscopic scale). At 7:33 this mysterious measurement devices that makes the interference disappear is actually and 'entangling' device. For instance, the position state of the particle can be entangled with the polarization state of the particle. Then measuring the position of the particle also reveals the polarization of the particle and we gain 'which slit' information and interference is destroyed. 8:50 the Schrodinger equation has the same form as the heat equation. The Schrodinger equation describes flow of probability. The difference is that the Schrodinger equation has a measurement problem and the heat equation does not.
Im a novice so im open to critique, but ive recently thought of super position in ridiculously simple terms. If a electron is revolving around a molecule at 99.99% the speed of light, its makes sense the math would describe it in terms of probability. Moving at that velocity in that small an area, it depends when you measure by the most infinitesimal measures of time where it will be.
It seems to me, that the missing variable in this question, is to full define “look like” Because what someone looks like is dependent upon an experience event. And to *experience* is not fully understood.
It might be helpful to introduce the notion that a periodic function (e.g. a sine wave) has a phase that (in the case of QM) is unknown beforehand. When a wave comes upon an edge or diffraction grating, the angle at which diffracts depends on the phase. If you use radio waves (instead of visible photons), the phase might well be known, and one can appreciate that the interaction at the edge of diffraction grating depends on the phase of the sinusoidal E-field. Not knowing the phase gives rise to the Schrödinger probability. If we knew the phase, we wouldn't need to model it as random.
I also thought like this, but also wondered if a radio wave photon has a too great a wavelength to also posses quantum properties. Lots of radio frequency (and electronics) equations also use the square root of -1, letter i to represent phase.
Good video. I especially like your explaining the limitations of such animations. Unfortunately, many science explainers do not fully explain the full meaning and the limitations of such depictions.
The way weak force bosons should be found mostly in the rest mass region of the wave function, but the ones that work in our Star are the very low mass rare ones and yet the Sun shines on. Don Lincoln explained it better. I am just awestruck.
I still believe that in order to move an electron or other object, you have to add photons to it. Each of those photons retains their peripolarity, and that interaction at the target is what gives us the interference pattern. And thats why it's the same sending atoms across. If that's true, then we should expect the same for alpha and beta particles as long as they are motivated by photons.
Lately I've been visualizing quantum particles as tangles of field lines rapidly jumping around spacetime. It's... Probably not right, or at all useful, but i havent yet been able to shake it with learning more science. It is kinda nice having an intuitive sense for quantum entanglement rhough, even if it's ultimately wrong.
If the particle is hitting a particular spot when observed is correct. And another particle hitting another spot is also correct because both incidents happen at different times. When we are observing it is a particular time we are observing and not the particle. If we rewind the recording that particle will hit that spot. If I am travelling between New York and London every day. Now on a particular day I am either in New York or london. But for an alien zooming in on me from Andromeda galaxy he cannot be sure where i am until he measures the exact time down to the particular day of the year. Since he is looking at the past he will always see a wave of probability. So in the quantum world if we are observing at the pico sec time scale every thing is a certainty but at the per minute scale every thing is a possibility. So it is impossible to observe anything at its current state. Every thing we observe is the past even though it might be only a second back. 🤔😎🤠
A proability wave sounds more like a metaphorical wave describing our knowledge about an outcome rather than anything physical. If so, reality as physical will need to be rewriten.
Arvin: Actually it does. Jim Al-Khalili has stated that the wave-like behaviour disappears when the computer in the other room is turned on and records the results and vica-versa when the recorder is turned off. So the particle knows that it is being watched (i.e. data is recorded in the room next door) and all while the physical interactions DON'T stop! Crazy...makes me want to assume the fetal position.
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Thank you for giving it a try, i.e., telling the most close to the truth to the mathematics of physics, instead of whatever tf the psychological operation was to "popularize" physics to the lay audience over multiple decades. If no one else dares to tell you: tyvm. Date: Saturday, August 17th, 2024.
Arvin uses the double-slit experiment to show quantum superposition, so let me resolve that mystery from the perspective of quantum information theory. This is explained in more detail in our book, "Einstein's Entanglement: Bell Inequalities, Relativity, and the Qubit" Oxford UP (2024), but I’ll summarize it here (as I did in a Comment for a previous Arvin video). According to the axiomatic reconstruction of quantum mechanics (QM) via information-theoretic principles (quantum reconstruction program, QRP), QM is a principle theory that follows from an empirically discovered fact called Information Invariance & Continuity (Brukner & Zeilinger 2009 wording). In more physical terms, Information Invariance & Continuity entails that everyone measures the same value for Planck's constant h, regardless of their relative spatial orientations or locations (let me call that the "Planck postulate"). Since h is a constant of Nature according to Planck's radiation law, the relativity principle (the laws of physics are the same in all inertial reference frames) says it must be the same in all inertial reference frames. And, since inertial reference frames are related by relative orientations or locations in space (rotations or translations), the relativity principle tells us the Planck postulate must obtain, whence the finite-dimensional Hilbert space of QM. The Hilbert space of QM is built from the most fundamental bit of quantum information (qubit) with its quantum superposition. A bit of information gives one of two answers when queried. The difference between classical probability theory with its classical bit of information and quantum probability theory with its qubit is that a classical bit can only be measured in one way while a qubit can be measured in infinitely many ways. This is exemplified by the double-slit experiment (as shown in Arvin's video). Start with the classical double-slit experiment where a laser of wavelength lambda illuminates a pair of slits in a screen with equal intensity and in phase. Now reduce the intensity of the laser until it is emitting one photon at a time with momentum p = h/lambda. The qubit state is then given by 50% Slit 1 + 50% Slit 2. [For those who know, I’m obviously describing probability amplitudes with probabilities.] That means if we place our detector right up against the slits (on the opposite side of the laser, obviously), then the probability that the photon is detected behind Slit 1 is 50% and behind Slit 2 is 50%, i.e., half the photons are detected behind Slit 1 and half behind Slit 2. The first mystery is, “Why photons? That is, as I reduce the intensity of the laser, why do I start getting dots with momentum p = h/lambda behind one slit or the other? If my laser emitted momentum p = h/lambda, why isn’t that p simply split equally between Slit 1 and Slit 2 as was the case when I started?” The answer per QRP is the Planck postulate. If that momentum was split into h/(2*lambda) behind each slit, then h would be effectively cut in half. That’s like moving through the luminiferous aether at c/2 and measuring the speed of a light beam to be c/2 (c = speed of light). The light postulate of special relativity (which the relativity principle also says must be true, since c is a constant of Nature per Maxwell’s equations and inertial reference frames are related by boosts) says everyone must measure the same value for c, regardless of their uniform relative motions. So, you will measure the speed of a light beam to be c even if you’re moving away from the source at c/2. Likewise, the Planck postulate says everyone must measure the same value for h, regardless of their locations in space. So, the momentum p = h/lambda emitted by the laser must land entirely behind one slit or the other, i.e., it cannot be split in half. The second mystery is, “Why quantum superposition?” Since the momentum is quantized, the classical result can only obtain on average, i.e., half the photons land behind Slit 1 and half behind Slit 2, so that the classical situation obtains on average. So, what happens if we move the detector far from the slits (compared to the slit separation)? In that case, the classical result is an interference pattern determined by lambda (as shown in Arvin's video). Since QM gives the classical result on average, that means the photons will land one at a time in a constructive interference fringe with 100% probability. And that means, 100% Constructive = 50% Slit 1 + 50% Slit 2 (which means we do actually see a superposition, contrary to what is often said in such videos). The ‘which slit’ measurement is a position measurement, and the ‘interference’ measurement is a momentum measurement (since interference is determined by lambda and lambda determines p). In fact, if the Slit 1 image region is left of center and the Slit 2 image region is right of center on the detector, then the outcomes for a ‘which slit’ measurement that are left of center are 100% from Slit 1, while those that are right of center are 100% from Slit 2. As you move the detector continuously farther and farther away from the slits, the probability that a photon detection left(right) of center is due to Slit 2(Slit 1) gradually increases until the detector gets to the ‘interference’ measurement location where the probability that a photon detection event left(right) of center is due to Slit 2(Slit 1) is 50%. That is, a photon detection event for the ‘interference’ measurement left of center is equally likely to be associated with Slit 2 as Slit 1 (vice versa for right of center). This is qubit superposition for the double-slit experiment. In conclusion, QRP says that QM is telling us how Nature behaves in accord with the relativity principle and Planck’s constant h, just like special relativity is telling us how Nature behaves in accord with the relativity principle and the speed of light c.
From a non-physicist, minimal math POV, physics at =< molecular scales seems to involve "areas of energy" that have only functional boundaries when considered as parts of systems, or collections of those areas of energy. In other words, no "particles" as balls of stuff, but "entities" of predictably variable areas of influence over and with other entities which are governed by energy/force, type/state.
this is not wrong per se, quantum states tend to share and distribute their properties in a relaxed kind of way, and only when they are vibrated by their environments to they collect back into bounded particle like states
Nice comment. I think science teachers really should drive this point home to students. I don't think many do. . Right, an energy wave is in a 3d volume area, with continuous intensity (amplitude) changes throughout this volume, thus making it an wave of energy. A lot of students are led by teachers to conceptualize this as a 2d pattern and get confused. Why do so many teachers do this? I mean, what we are talking about here isn't a science basic, it's a fundamental. Can you imagine if jet pilots taught flying fundamentals half ass? Jets would be crashing all over the place. That's the thing, flight instructors can't get away with half ass douche bag teaching. Science teachers can, and many do. Especially many teaching in American high schools. I wrote more as a comment to dhudach above, if you are interested. Thanks for the comment.
Reality is rendered to conscious beings on the fly, based on probability. But it has to be consistent with information that already exists in the system
The pattern you show at 7:34, the two bands, never happens with photons. If you determine the which way information the double slit interference pattern will disappear, and it will be replaced by a single slit interference pattern.
As someone who uses statistics in their profession on a daily basis, quantum mechanics became less mystical after this video. I like the idea of things being in two places at the same time though. It makes for good sci-fi.
I describe it in reference to the vertical line test of graphing to see whether or not something is a function or not. If it fails the vertical line test, it's not a function; it's quantum mechanics. If you want to know where the particle actually is, you gotta go through the tedium of walking the line to see where it is.
Thank you to Ritual for Sponsoring this video. Get 25% OFF your first month at ritual.com/arvinash
Do they sell the red pill or the blue one? 😊
lol you didnt wanna mention your pill is based on a EXTREME BIAS but thats cute...lol I get why...lol SABINE may not however. lulz
Wave spread is due to quantum gravity and particle gravitates by observer 😅😅😅
When particle single photon released, how does observer device captures ? Photon speed is speed of light??? Observer device shoots another photon, To detect photon?
When photon when not observed is it in wave form because of quantum gravity?
When observed its gravity changes and hence particle?
@@priyakulkarni9583 Yeah that's what Roger Penrose says. When the superposition/wave is "too heavy", the spacetime curvature it creates shrinks it into a dot-like particle.
Schrödinger Equation: “It may look complicated… and it is” Appreciate that Arvin 😆
And yet he had to dumbed it down to be about energies. It is not about that.
@@jr.bobdobbsSlack!
@@jr.bobdobbs What should it be if he didn't dumb it down? 🤔
Loved the video, especially the part where you debunked the misconception that superposition is NOT the same thing as being at multiple locations at the same time.
But, on a similar line, saying ‘electron goes through both slits’ is also a gross over simplification!
Infact if you use any words to explain what the electron is doing, we will end with a misconception.
And so I think the most accurate way to think about it is that the electrons are not going through either of the slits. They are not going through both. They are also not going through neither. This exhausts all the possibilities we can think of and yet, the electron is doing something involving both slits.
And that something is termed a quantum superposition. And that’s that. You can’t articulate what quantum superposition is using any language (except math). You can only ever tell what it is not!
Hahaa I love that comment, that's an Idea that could have gone past me for a long time as a mere enthusiast.
Indeed, superposition is our inference about experimental results, rather than a phenomenon that can be directly confirmed through experiments. There is no experiment that can prove superposition, or show that a quantum particle can simultaneously pass through two slits, or that superposition is canceled upon detection. These are all imprecise statements with no experimental evidence to support them.
Basically, the slits and their properties affect the probability wave?
@@Hacker4748 yup, but nobody ever illustrates the fact that most of the probability cloud is reflected back toward the emiter
That's true Mahesh, but you know as well as he does that it's always a compromise between clarity and accuracy. In fact, this is the first time i've seen anyone show a more accurate depiction of what the probability cloud actually looks like going toward the slits. He just closed up a glaring omission in almost every video i've ever seen. Of course it's true that, as the Buddhists say, the moment you open your mouth, you're off target, but they still have a great deal of literature that i'm quite grateful for. And speaking of Koans, nobody has ever addressed the stern-gerlach paradox. Maybe you should do a talk about that.
I think people should read Schrodinger's book _"Nature and the Greek and Science and Humanism."_ Schrodinger had originally argued for using the wave function to replace Heisenberg's original formulation of QM where particles don't have real states between interactions and only have real states in the moment of interaction. Schrodinger hated this, saying "I do not believe the electron hops about like a flea." However, Schrodinger realized that introducing the wave function to fill in the "gaps" between interactions just introduces a new "gap" between the continuously evolving wave and its "collapse" upon measurement, and thus in that book Schrodinger argues in favor of returning to the Heisenberg picture. QM is far more intuitive if you treat it like this and all the "paradoxes" have simple explanations. The only thing that is _real_ is the particle's state during an interaction, there is no _reality_ of it in between interactions. If you accept this one premise then the rest of quantum mechanics follows without introducing a fundamental role for measurement, spooky action at a distance (nonlocality), particles being in two states at once, collapsing wave functions, a multiverse, some sort of special role for the conscious observer, so on and so forth. All of QM follows from just one principle that reality is made up of events and not autonomous objects and that objects "hop about like a flea" between interactions predictable by mathematical laws.
Thanks, that answers a question I've been having for a few years. I've had a working knowledge of QM at about the level of this video for decades. I did not realize there was a "measurement problem" until I started watching RUclips physics video's. What problem? I just didn't get it (I still don't). If you assume a particle to exist as something like a probability wave, isn't what the experiments show exactly what you'd expect to see? Why are we not done here?
"The only thing that is real is the particle's state during an interaction, there is *no* reality of it *in between* interactions."
Hmmmm... what if the interaction is "on" all the time? like between electrons in a heavy atom? or constituents of a solid?
@@GeoffryGifari those electrons would be interacting as probability waves and then you’d still need to measure them to figure out their state forcing them to be localized and collapsing the wave function, so the problem is the same.
Btw the original comment is a great explanation of the measurement problem and I commend you for the lengthy explanation.
@@salahlamsaoub7753 hmmm but at what point does interaction between subsystems count as a measurement? why can't we say that electrons in an atom measure each other? how big/separated should a system be until interaction counts as measurement?
So basically, we don’t know exactly where the particle actually is before we measure it, so we came up with a mathematical formula that expresses this “where it might be” as a probability wave. We can say the same thing about tomorrow’s weather. There is a 30% chance it might rain, or a 70% chance of being a sunny day. Until it actually happens, we don’t know for sure, so we use a probability to describe it. When we do measure the electron, of course then we know where it actually is, so the probability prediction is no longer applicable after that. The mind bender is that, the double slit experiment proves that this probability wave that we made up IS actually happening in reality before we measure the particle.😮
You should reach "The Theory of Raikons"
Thanks for the video. I usually watch your videos and really enjoy them, but for this video I have a couple of comments: 1. A measurement is NOT just an interaction. Inside a solid numerous electrons that are in superposition are interacting, but none is measured. Also two hydrogen atoms interacting with Van der Walles force are not being measured, but they still interact. In fact, there is no equation showing what a measurement is (there is no equation describing wavefunction collapse).
2. If you take Schrödinger’s equation seriously, meaning that you take it as really describing reality, then a superposition is the existence of “multiple histories” of the particle. Once it interacts with a macroscopic measurement apparatus, each part of its superposition becomes entangled to it and to its numerous degrees of freedom, generating a practically random phase to its part of the superposition. Once you make many experiments with superposition states that have random phases between them, they no longer interfere with each other (decoherence). In some way all the measurement possible outcomes co-exist but they can no longer interfere with each other. But again, this is if you take the Schrödinger equation seriously and not merely as a calculation tool only.
3. The wavefunction being a complex number has nothing to do with it being non-physical. In fact, one can formulate quantum mechanics without complex numbers, it will just be very cumbersome. Furthermore, even a pendulum amplitude and phase can be described with complex numbers, and it surely is physical.
In summary, all while one ignores the measurement part and treats it like magic, then one gets to failed and inconsistent interpretations.
I would like to see Arvin Ash comment on all you points. I tend to agree with your summary (though I don’t know much / I’m certainly no expert). 🍂🍃🌈
Finally someone who gets it. I recommend watching a video by Eugene Khutoryansky called "Quantum Measurements are Entanglement" here on RUclips.
For your first point.
In video it is said that measurement is an interaction, it doesn't imply, that all interactions are measurements.
For example, in double slit experiment you can measure a particle on the slits with light. It will break interference picture, as mentioned in video. But ONLY if light's wavelength is actually less than the distance between slits, so that you can certainly find out through which slit the particle have passed. Otherwise the interference picture would not be broken.
@@sn3232 What needs to happen at the slits is entanglement between multiple degrees of freedom. Amplifying that entangled state and collapsing it is a measurement. It's the collapse we don't fully understand. You are correct that it is possible to have interaction without measurement.
I'm not a scientists, just someone interested in the strange world of quantum mechanics. Over the past 30+ years I have read many, many books on the topic written by reputable scientists and authors. You have essentially summarized all of them in this video. Outstanding. You've managed to lay out the problem piece by piece in layman terms without sacrificing some technical areas. But I have a question. You talk about the electron wave approaching the double slit and when it hits the screen we know its location. What is the electron when it is fired toward the screen? Is it a particle that turns into the wave? How do we send electrons to the screen and do they start as particles or waves? It's like the story of the little boy walking down the street holding a burning candle. A wise man approaches the boy and wishing to teach him a deep lesson and make him think, he blows out the candle and asks the boy, "Young man, where did the flame go?" The young boy thinks about it then replies, "You tell me where it came from and I'll tell you where it went."
In your example there are two instances where the position of the electron is known: when it is emitted, and when it hits the screen. Both of those can be considered interactions (or observations.) At both those instances the electron acts like a particle. In between those instances you are not interacting with the particle, so it is acting like a wave. It is in between interactions that an object acts like a wave, and it is at the point of interaction that it acts like a particle. There can be many interactions in the lifetime of an object (say, an electron), so it can alternate between the wave and particle behavior many times.
@@ezhb1nj Ok thanks for shedding some light on this for me.
What I got out of this video is that the electron in its wave state is energy organized a certain way in a particular area. When in this state, it has continuous energy level (amplitude) changes throughout the 3d volume that this electron exists in, thus called a wave. I'm guessing that it is an active, projected energy in the realm that we live in and can perceive to an extent, and was latent ( or maybe active) in another realm that we do not understand, before it was projected. The device with the cathode was what projected this latent energy into our realm that we perceive and live in. Also, perhaps the electron quantum field is an energy field that is organized in a way so that it acts as a mechanism that is a kind of aperture between both realms. or maybe this latent energy is part of the electron field itself. Or, maybe this latent energy induces latent energy of the electron field to become active. The electron wave comes into our realm by means of the quantum electron field mechanism. When it interacts with a photonic device, such as a flourescent screen, the interaction changes the electron wave's organization in a way so as to cause a particle effect on the device, which, maybe, could be called a further induced manifestion.
Imagine this. You are in complete blackness with nothing around you. A light emerges behind you, shining in all directions. But we aren’t looking at it. It is there, particles of light, traveling in waves. But we don’t see any of it. The reason is that we need the photon to interact with our retina in order to observe it. The eye is a directional antenna tuned to the EM energy we call light waves.
When the photons bounce, reflect, off of something in front of us, or if we turn to look, we see it is there. It always was. The photon has to hit the retina.
This next is not a great example of quantum but illustrates the mental concept of superposition and interaction.
We are bathed in local radio waves from radio stations. As long as we don’t tune in to it, (observe) we do not know it’s even there. It is said to be in a superposition. (Bad example again)
But when we tune into it, we interact with it. We observe it. The thing is, other observers from other locations can observe the same field.
Light or radio. The field does not collapse through observation. We simply grab one particle. And when we launch it. It can only move in it’s wave form. The frequency of it.
Lay man here
But let me explain what I understand on the subject
An electron is a small packet of energy in a tiny volume of 0 dimensions. So small you can't measure it's volume.
You know its exact location when you are firing it, and you know it's location when it hits the screen.
It between you don't know it's location.
The electron is not a wave in between, but the information of it's location is a probability, and the wave pattern is directly related to this undeterministic property of it's location.
This is very unintuitive but a law of nature due to Heisenberg uncertainty principle.
Other than that we don't know much about the exact shapes, forms of quantum objects.
Are they waves themselves in that infinitesimally small volumes? Maybe, string theory postulates them to be wiggling objects, like a wave. But string theory is mostly a dead end, some other theory in the future might still prove them to be waves themselves well.
This is a short summary of what my limited understanding of quantum physics.
I could elaborate some more but not much more, due to limits of what I know.
“The math of quantum mechanics does not describe the universe.” All the mysticism surrounding QM disappeared for me when I realized that we have no math, no physics at all, to describes the unobserved quantum world. The wave function and the Schrödinger Equation only describe the classical view of things.
Meanwhile quantum mechanics says, “Yeah, well, you know, that’s just like uh, your opinion man.”
dude.
I don't think nature has that dismissive quality than humans have sometimes. I just think it is shy and doesn't offer up information about how it works easily.
@@fig7047yes
Quantum Mechanics just wants it's rug back.
@@davemiller6055 seems like you’d have to do a fence war with crystals and symmetry. Take no prisoners.lol
Particles before measurement exist in a future state. Because causality has a speed limit (c) every point in space where one observes it from will be the closest to the present moment. When one looks out into the universe they see the past which is made of particles (GR). When one tries to measure the position of a particle they are observing smaller distances and getting closer to the present moment (QM). The wave property of particles appears when we start trying to predict the future of that particle. A particle that has not had an interaction exists in a future state. It is a probability wave because the future is probabilistic. Wave function collapse is what we perceive as the present moment and is what divides the past from the future. GR is making measurements in the observed past and therefore, predictable. It can predict the future but only from information collected from the past. QM is attempting to make measurements of the unobserved future and therefore, unpredictable. Only once a particle interacts with the present moment does it become predictable. This is an observational interpretation of the mathematics we currently use based on the limited perspective we have with the experiments we choose to observe the universe with.
Thanks for great explanation, does it also mean that past has influence on future , and future on the past, as some sort of looping?
This will be very interesting. In the future.
I think people should read Schrodinger's book _"Nature and the Greek and Science and Humanism."_ Schrodinger had originally argued for using the wave function to replace Heisenberg's original formulation of QM where particles don't have real states between interactions and only have real states in the moment of interaction. Schrodinger hated this, saying "I do not believe the electron hops about like a flea." However, Schrodinger realized that introducing the wave function to fill in the "gaps" between interactions just introduces a new "gap" between the continuously evolving wave and its "collapse" upon measurement, and thus in that book Schrodinger argues in favor of returning to the Heisenberg picture. QM is far more intuitive if you treat it like this and all the "paradoxes" have simple explanations. The only thing that is _real_ is the particle's state during an interaction, there is no _reality_ of it in between interactions. If you accept this one premise then the rest of quantum mechanics follows without introducing a fundamental role for measurement, spooky action at a distance (nonlocality), particles being in two states at once, collapsing wave functions, a multiverse, some sort of special role for the conscious observer, so on and so forth. All of QM follows from just one principle that reality is made up of events and not autonomous objects and that objects "hop about like a flea" between interactions predictable by mathematical laws.
This is very interesting and I'm glad you posted it. I'm still trying to fully wrap my head around this viewpoint. There are major questions that are asked by this, such as, what does this imply about gravity and the other forces? This seems to imply an inherent asymmetry between the future and the past which may be fundamental or consequential.
Can we then talk about forces moving things from past to future or vice versa? Gravity is an effect in the past acting on the present I suppose. But the quantum forces, would we say they act in the future or the present? And which direction do they tend if any? And is this an absolute future or a relative future? If I measure a particle in the present, does that destroy its quantum properties for other observers?
Causality = “C+1” and not just “C”.
It’s observed with black holes that “trap” light itself because the pull is faster than the speed of light.
I think that the much-maligned "shut up and calculate" position is much more insightful and deep than most people imagine.
Shut up and calculate means to give up to solve the measurement problem.
@@Thomas-gk42 The measurement [problem isn't a problem in the world, its a problem in people's heads, and has been solved in more than one way, decoherence, entanglement, etc.
What it does mean is to stop arguing philosophy and to start doing science.
@@ozzymandius666 Stop doing philosophy and start doing science is a good slogan, but the measurement problem is an inconsitency that needs to be solved in science, not in philosophy. It means, that we don´t understand what physically happens in the measurement process. To understand it, could bring progress in science and technology.
@@Thomas-gk42 but there is the possibility that there is nothing to solve at all. You can debate this. It does not mean that you should not try to solve it, but it may be worth to prove that it can't be solved, similar to Godel's incompleteness theorem in mathematics.
@@rutger4131 I agree, but if we have the possibility to observe the gravitational field of more and more massive objects, we should do that instead of the thousandth Bell-like experiment.
2:01 "Multiple states at the same time"
Yes, a Gross simplification.
Superposition has always disturbed me till now, and I hate how widely the information is spread..
And also, "The math of quantum physics doesn't describe the math of the universe, it describes what we'd get if we made a measurement" ❤
Thanks for the beautiful line, Arwin Ash. I also approve your statement because it is just to simplify our caluclations..
Also, a big thanks for the animation for the 3D probability density of the electron through the double slit! I really wanted it 😄
I should've taken the blue pill.
😂
I feel like I took both...
Well, you took neither 😂😂…I mean blue being observed as blue and red observed as red…😅
@@NiranjanNanda 🤣"Schrödinger's Pill?"
My boxed cat feels better now. Thank you, Arvin!
@thezone5840 They came before you called them. 🙂
1:13 damn it Arvin... I need both to feel the superposition 🔴🔵
Just a suggestion, you should reach the theory of Raikons.
As a photographer I’ve always felt it’s easiest to picture measuring quantum particles as akin to cranking up the shutter speed to capture a fast moving object, but now it’s stationary, you know precisely where it is but you can’t tell any motion apart, and as such you no longer know where it’s going, you could crank down the shutter speed somewhat and still get some motion blur, but it wouldn’t give you all the info on motion. Maybe it’s similar to this principle but the breakdown between the two happens over a much narrower range with quantum particles.
That sounds like an analogue of Heisenberg's Uncertainty Principle, but not really wave function evolution/collapse.
@@stormapproaching oh, sorry, I must have gotten confused and forgotten my brain somewhere
Not a bad analogy. The observer wave synchronizes with the observed wave so it appears solid, like the props on a movie can appear still when synced to the frame rate. But they are ALWAYS ONLY waves, particles are a figment of our reaction time..
1:25 accidentally stopped watching the vid at that moment and only today I remembered to watch the rest 😂
Instead of firing through 2 parallel slits, I may suggest experimenting with firing at an "X", or "XX" crossed slits to test for chirality or supplemental effects.
One of the best explanations of wave-particle duality I've watched. Well done.
Congratulations on 1m subs!!
Love your videos sir they provide so much knowledge ❤❤
A police officer pulled over Heisenberg, and asked “Do you have any idea how fast you were going?" Heisenberg re[lied, “No but I know precisely where I am.” The cop says “You were doing eighty miles an hour.” “Oh great!” says Heisenberg. “Now I’m lost!”
Are you certain thats what happened?
QM works within it's own context. It's a description of a limited range of phenomena. It's a placeholder waiting for a finished theory of everything.
We use QM because we're not gods.
4:00 minutes in, I feel like this video was made for me. Great job.
Thanks for clarifying the "superposition" meaning.
Intuitively, superposition defined as existing in multiple places at the same time seemed very wrong.
I suggest that whatever the electron is doing (or what it "looks like") as it moves between the double-slitted wall and that of the phosphorescent screen is the closest we can come to understanding what an actual Kantian "noumenon" is all about. In other words, it is something that is "real," but can only be imagined and never directly perceived.
Thank you for that more elaborate definition of……”superposition=I have no idea where the thing is”.
The critical issue is the question, "What is a particle?" Arvine Ash correctly highlights that the mathematics of Quantum Mechanics focuses on detection rather than the particle itself. In this context, a "particle" is the portion of a wave that we can measure. The distinction between classical and quantum waves lies in how they can be observed. With classical waves, you can assess the entire wave-its height and length-by observing it along the beach. In quantum mechanics, however, you can only pinpoint the "particle" (or measurement) at a specific point on the beach. Note * that doesn't mean, the wave disappeared during the measurement, it means we can only interact with the wave at one point.
So something like taking a snapshot? From what I've understood so far, a quantum "particle" is the tiniest excitation/disturbance of a quantum field.
You can actually measure "quantum wave" at any point, that's what screen in double slit experiment does.
The difference with "classical" wave is that the measurement is such a strong interaction it actually changes the state. Thus it can only be detected once and during this detection it is changed by the interaction.
That's quite contrary to what you wrote, that "wave doesn't disappear".
@rickfrombohemia9550
If you take a snapshot of a classical wave you would see the whole wave on the picture. With "quantum wave" you would see only one particle in a specific place, this is shown on 3:50, except for the part, that "wavy thing" on the video is not detectable.
To reconstruct the wave you would have to repeat the experiment many times, taking many snapshots. If you then put the dots, representing a particle on the same picture, you will see, that some positions are more probable. That's why it's sometimes called "probability wave". The process is shown on 6:53.
PS:
This video is only concerned with quantum mechanics, which operates with particles, and does not say anything about their nature. Notion of a particle as a quantum field excitation is coming from quantum field theory, which is a different discipline.
@@sn3232 Maybe a particle can be in more places at the same time, but since it's actually a quantum object, it means something different and more abstract than in our classical world. We just don't know how much different I guess. We can't imagine it, just describe it mathematically.
@@sn3232 I am trying to distinguish between what we know and what remains uncertain. We do not know if there is a round ball or "particle" in the traditional sense. In fact, I doubt the existence of any round ball; it seems more like a point where two fields interact and exchange energy. What we do know is that there is an energy exchange occurring at a tiny point within the detector.
Moreover, when we sum up these energy exchanges, the overall behavior resembles a wave. However, this is unlike any "classical" wave we've encountered. While this doesn’t rule out the possibility of it being a wave, it suggests that it's unlike anything we've experienced with our senses. Could this be a "fourth-dimensional" or higher-dimensional wave within the fabric of space-time? We don't know for sure, but it seems plausible and potentially testable.
I'm thinking that probably what's going on can best be thought of in terms of quantum field theory. There is no particle but rather a peak in the field in a given area, like how a wave in the water has a highest point. The wave, with a peak as all waves have, isn't isolated but rather spread out over a given amount of space, and constantly moving around at high speed. So when the measurement is made we are simply seeing the highest point of the peak, wherever it is in that instant, and the interaction of taking the measurement has a flattening effect on the rest of the wave so we just see it as a point. So I'm thinking the supposed particle/wave duality is really just a contradiction created by our perception. There is no particle, it's all just waves, and we just label the highest peak of the wave as a particle since it has a definite position once we destroy the rest of the wave by the interaction of measuring. But I'm no particle physicist and I'm basically just talking out of my arse here lol.
The statement at 7:14, "this can only happen if the electron goes through both slits at the same time and interferes with itself"' Presents a solid conclusion about a phenomenon that still puzzles us, or in fact is unknown.
True
no. watch an actual simulation of a quantum particle and it will be self-evident how this happens -- the wavefunction or wavepacket indeed behaves like a wave.
@@anywallsocket It behaves/manifests like a wave, but actually isn't and we don't or probably even can't know what it really is.
@@rickfrombohemia9550 what do you mean you can't know what it really is? you mean you can't relate it directly to something you're already familiar with? have you seen the simulations? that is what it really is, it is what the mathematical equation is modeling.
@rickfrombohemia9550 it seems a little beyond the physical little instead of blatant interaction it appears to be "behind" regular matter like a deeper layer and beyond the 4th dimension
All you need is entropy. Plank time is the universe's SLA on processing entropy transactions, which need to be registered. While I used to think in terms of interactions, or changes in the possibility space, Im realizing that observer interactions need to lead to a change in entropy, which sorta commits the universe state to memory - entropy is one-way - but if that doesnt occur, the universe can keep the threads running in parallel, and you get double slit patterns.
I engineer. I often use the thought experiment: the universe has some constraints, and seemingly never halted. Relativity and time dilation are a great way to prevent too many interactions from happening at once. Keeping with the exercise of being in the developer's head, without truly unlimited resources, Id want to use parallel threads and limit state updates as much as possible, and if there's no point, why bother. Well, there needs to be a quick way to determine if an interaction needs to be evaluated, and the singular one-way, 'if not null,' is entropy. If there is any change in entropy, it becomes fundamentally causal, but by definition, an interaction is fungible if there isnt a entropy change in the system => superposition/wavefunction thread, entropy affecting interaction == waveThread.join(main)
Wow almost 1 million subs! Early congrats to Arvin & crew, keep up the fantastic work!
What's important to understand is that the dimensions of the slit matter when single electrons are fired through the slits to get visible proof of superposition, which then resolves itself into a single particle at the scintillator screen
I agree. That's a decent explanation. I've been saying pretty much the same thing for years and it's refreshing to hear a practical classical explanation. Something you may not realize is that quantum bits in superposition are hidden local variables. And a correlation of measurement by Alice and Bob can never be over 2 in reality. The violations of bells inequalities those experiments are nonsensical once you boil down to the basics. The take correlations over many instances to get to 2.8, which doesn't actually exist in reality.
Excellent explanation
4:28 finally someone has guts to say garbage 😂😂😂 love that
Nice animation....I will ask my students to watch 😊
Great one!, as usual. I love the way how you start from (seemingly!) mundane things to navigate through the magical world of Quantum physics!
Arvin
Thank you for these great videos. Much appreciated.
Please do a video on the technology and method used to measure these particles.
They say, “see.” How do you “see?”
Thanks
"garbage" just after Deepak Chopra photo is appropriate.
Thank you Arvin for the clear and easy to understand explanation on quantum states.
The superposition is the quantum version of "known unknowns". We don't know where it is, only where it can be. All knowledge is approximate knowledge. If no less invaluable.
Thank you for that. For a layman trying to get to grips with waves and individual entities it is very helpful.
Good explanation.
It's 1:30 in and i've been wondering this for at least 10 years, i have never been so excited to see a video
I know this video is made for dumbbells like myself, but my brain still has difficulties understanding what’s going on.
Don't feel bad. Feynman said, “If you think you understand quantum mechanics, you don't understand quantum mechanics.”
If I were to summarize the video: we don’t know what particules are or where they are before we interact with them, we can only calculate the probability of their location.
it's okay it is explained confusingly anyway, like he keeps showing particles prior to measurement, and also shows waves made of particles? like dude, we have real simulations showing what the actual wavefunction looks like, be it one particle or many...
To make things easy I usually tell people that, try to think as particles not existing until they have to. The wave before a particle is a wave of probability for potential particles that will come into reality when it's forced to. Even if this may not be how it really works, no one really knows yet, it's a good start to understand the weird implications of Quantum Mechanics.
@@karlkarlsson9126 But how can potential/"unreal" interact with actual/"real"? Doesn't it have to be actual in the first place in order to interact (i.e. exchange energy)? If it is indeed potential, shouldn't we use different term than interaction?
My personal answer before watching the video:
Superpositioned particles don't look like anything,as looking at them is measuring them, thus breaking the superposition
The intro with the pills was so funny.
Nice! Great explanation of something that is usually poorly presented. A bit like you've measured the probability wave of bad RUclips quantum physics clips and resolved it to a single point 😂
Cool...pretty intuitive explanation of wave function.
Isn't the Schrodinger equation just a function of space-time. You can think of space-time as a liquid and the particle as a bubble. Fire that bubble at the slits, it splits apart forming two bublets, which interfere with each other on the other side and so form the interference pattern. Job done!
Great video Marvin, thanks❤
There was a form of the double-slit experiment where they used positrons as well as electrons, and showed that they could interfere without annihilating.
Excellent- probably the best explanation I have seen.
Great sir salute
Quantum Pill. Having both until I choose.
I like the green wave of particles graphic!
Thank you so much! :-) This explanation is a real „eye opener“.
It is simple, it is just rendering. No multiple locations. Most of the scientists are desperate to find material but there isn't. It is just information within a ruleset.
Well put
An Arvin Ash red pill... Just what the doctor ordered. 💊
In fact, as a result of the measurement of a quantum system, irreversible changes occur in the state of the measuring device, which we can read and interprete them for the translation into specific values of states of the measured quantum system.
I'll be honest, the "simple" explanation never made any sense whatsoever to me, and I thought I was just dumb. Good to see that I'm not.
Almost 1M subs!!!
How do quantum particles behave when no one is looking? They party like it’s 1999! 😛
I commend your effort and how you keep coming back to this subject. I have some notes, see below. I look forward to the next revision ;)
2:15: Whether or not you ascribe physical reality to the wave function (ontic) or that it only describes observations (epistemic) is (at the moment) an interpretational / philosophical issue. Both are valid (though you may disagree passionately with one or the other).
6:43 It is not just the electron which is described by the wave function. The wave function describes the entire experimental setup. Because most of the setup is macroscopic, we can describe the experiment for the most part with just a small portion of the total wavefunction. But you should not forget that in reality, the wave function is much bigger than the single particle approximation. There may be the misconception that each particle has it's own wavefunction. This is not so. A system with two, three, a million particles is described by one single wave function. That's one of the reasons why these animations never work out to create a true quantum picture.
A measurement is (at least partially) amplified entanglement (amplified to macroscopic scale). At 7:33 this mysterious measurement devices that makes the interference disappear is actually and 'entangling' device. For instance, the position state of the particle can be entangled with the polarization state of the particle. Then measuring the position of the particle also reveals the polarization of the particle and we gain 'which slit' information and interference is destroyed.
8:50 the Schrodinger equation has the same form as the heat equation. The Schrodinger equation describes flow of probability. The difference is that the Schrodinger equation has a measurement problem and the heat equation does not.
Im a novice so im open to critique, but ive recently thought of super
position in ridiculously simple terms. If a electron is revolving around a molecule at 99.99% the speed of light, its makes sense the math would describe it in terms of probability. Moving at that velocity in that small an area, it depends when you measure by the most infinitesimal measures of time where it will be.
It seems to me, that the missing variable in this question, is to full define “look like”
Because what someone looks like is dependent upon an experience event.
And to *experience* is not fully understood.
It might be helpful to introduce the notion that a periodic function (e.g. a sine wave) has a phase that (in the case of QM) is unknown beforehand. When a wave comes upon an edge or diffraction grating, the angle at which diffracts depends on the phase. If you use radio waves (instead of visible photons), the phase might well be known, and one can appreciate that the interaction at the edge of diffraction grating depends on the phase of the sinusoidal E-field. Not knowing the phase gives rise to the Schrödinger probability. If we knew the phase, we wouldn't need to model it as random.
I also thought like this, but also wondered if a radio wave photon has a too great a wavelength to also posses quantum properties. Lots of radio frequency (and electronics) equations also use the square root of -1, letter i to represent phase.
No. You still get interference patterns dictated by the Schrodinger equation even if you know the electron's phase (aka spin).
That interference pattern looks like the outline of a 3D object. Horizontally it looks like a cylinder and vertically it looks like a gear.
Thankyou for being very clear about what the animations are trying to communicate. There are indeed a lot of wonky ideas out there.
Another wonderful video. Onwards to 1M subscribers!
Good video. I especially like your explaining the limitations of such animations. Unfortunately, many science explainers do not fully explain the full meaning and the limitations of such depictions.
The way weak force bosons should be found mostly in the rest mass region of the wave function, but the ones that work in our Star are the very low mass rare ones and yet the Sun shines on.
Don Lincoln explained it better. I am just awestruck.
Arvin Ash is the GOAT
I still believe that in order to move an electron or other object, you have to add photons to it. Each of those photons retains their peripolarity, and that interaction at the target is what gives us the interference pattern. And thats why it's the same sending atoms across. If that's true, then we should expect the same for alpha and beta particles as long as they are motivated by photons.
Lately I've been visualizing quantum particles as tangles of field lines rapidly jumping around spacetime. It's... Probably not right, or at all useful, but i havent yet been able to shake it with learning more science.
It is kinda nice having an intuitive sense for quantum entanglement rhough, even if it's ultimately wrong.
This is the best explanation 👏🏾
This is one of the best videos I've seen from you 👍 thank you!
If the particle is hitting a particular spot when observed is correct.
And another particle hitting another spot is also correct because both incidents happen at different times.
When we are observing it is a particular time we are observing and not the particle. If we rewind the recording that particle will hit that spot.
If I am travelling between New York and London every day.
Now on a particular day I am either in New York or london.
But for an alien zooming in on me from Andromeda galaxy he cannot be sure where i am until he measures the exact time down to the particular day of the year.
Since he is looking at the past he will always see a wave of probability.
So in the quantum world if we are observing at the pico sec time scale every thing is a certainty but at the per minute scale every thing is a possibility.
So it is impossible to observe anything at its current state. Every thing we observe is the past even though it might be only a second back. 🤔😎🤠
I wish you do a program on what we really have verified by observation versus what scientist speculate based on mathematics.
A proability wave sounds more like a metaphorical wave describing our knowledge about an outcome rather than anything physical. If so, reality as physical will need to be rewriten.
It is inherently uncertain at what point in time a measurement is definitively defined.
So close to 1M subscribers!
Great video. I would LOVE a deep dive in to the experimental mechanics of 7:24-7:35.
Great video !
Arvin: Actually it does. Jim Al-Khalili has stated that the wave-like behaviour disappears when the computer in the other room is turned on and records the results and vica-versa when the recorder is turned off. So the particle knows that it is being watched (i.e. data is recorded in the room next door) and all while the physical interactions DON'T stop! Crazy...makes me want to assume the fetal position.
Thank you for this video
OMG !!!! I found this channel today, it has veery important and intresting videos regarding science 😳🤩 I love itttt! ❤
Thanks to the creator of this channel, who's giving such impressive knowledge in free of cost with more clear explanation!😅
Thank you for giving it a try, i.e., telling the most close to the truth to the mathematics of physics, instead of whatever tf the psychological operation was to "popularize" physics to the lay audience over multiple decades. If no one else dares to tell you: tyvm.
Date: Saturday, August 17th, 2024.
Arvin uses the double-slit experiment to show quantum superposition, so let me resolve that mystery from the perspective of quantum information theory. This is explained in more detail in our book, "Einstein's Entanglement: Bell Inequalities, Relativity, and the Qubit" Oxford UP (2024), but I’ll summarize it here (as I did in a Comment for a previous Arvin video).
According to the axiomatic reconstruction of quantum mechanics (QM) via information-theoretic principles (quantum reconstruction program, QRP), QM is a principle theory that follows from an empirically discovered fact called Information Invariance & Continuity (Brukner & Zeilinger 2009 wording). In more physical terms, Information Invariance & Continuity entails that everyone measures the same value for Planck's constant h, regardless of their relative spatial orientations or locations (let me call that the "Planck postulate"). Since h is a constant of Nature according to Planck's radiation law, the relativity principle (the laws of physics are the same in all inertial reference frames) says it must be the same in all inertial reference frames. And, since inertial reference frames are related by relative orientations or locations in space (rotations or translations), the relativity principle tells us the Planck postulate must obtain, whence the finite-dimensional Hilbert space of QM.
The Hilbert space of QM is built from the most fundamental bit of quantum information (qubit) with its quantum superposition. A bit of information gives one of two answers when queried. The difference between classical probability theory with its classical bit of information and quantum probability theory with its qubit is that a classical bit can only be measured in one way while a qubit can be measured in infinitely many ways. This is exemplified by the double-slit experiment (as shown in Arvin's video).
Start with the classical double-slit experiment where a laser of wavelength lambda illuminates a pair of slits in a screen with equal intensity and in phase. Now reduce the intensity of the laser until it is emitting one photon at a time with momentum p = h/lambda. The qubit state is then given by 50% Slit 1 + 50% Slit 2. [For those who know, I’m obviously describing probability amplitudes with probabilities.] That means if we place our detector right up against the slits (on the opposite side of the laser, obviously), then the probability that the photon is detected behind Slit 1 is 50% and behind Slit 2 is 50%, i.e., half the photons are detected behind Slit 1 and half behind Slit 2.
The first mystery is, “Why photons? That is, as I reduce the intensity of the laser, why do I start getting dots with momentum p = h/lambda behind one slit or the other? If my laser emitted momentum p = h/lambda, why isn’t that p simply split equally between Slit 1 and Slit 2 as was the case when I started?” The answer per QRP is the Planck postulate. If that momentum was split into h/(2*lambda) behind each slit, then h would be effectively cut in half. That’s like moving through the luminiferous aether at c/2 and measuring the speed of a light beam to be c/2 (c = speed of light). The light postulate of special relativity (which the relativity principle also says must be true, since c is a constant of Nature per Maxwell’s equations and inertial reference frames are related by boosts) says everyone must measure the same value for c, regardless of their uniform relative motions. So, you will measure the speed of a light beam to be c even if you’re moving away from the source at c/2. Likewise, the Planck postulate says everyone must measure the same value for h, regardless of their locations in space. So, the momentum p = h/lambda emitted by the laser must land entirely behind one slit or the other, i.e., it cannot be split in half.
The second mystery is, “Why quantum superposition?” Since the momentum is quantized, the classical result can only obtain on average, i.e., half the photons land behind Slit 1 and half behind Slit 2, so that the classical situation obtains on average. So, what happens if we move the detector far from the slits (compared to the slit separation)? In that case, the classical result is an interference pattern determined by lambda (as shown in Arvin's video). Since QM gives the classical result on average, that means the photons will land one at a time in a constructive interference fringe with 100% probability. And that means, 100% Constructive = 50% Slit 1 + 50% Slit 2 (which means we do actually see a superposition, contrary to what is often said in such videos). The ‘which slit’ measurement is a position measurement, and the ‘interference’ measurement is a momentum measurement (since interference is determined by lambda and lambda determines p).
In fact, if the Slit 1 image region is left of center and the Slit 2 image region is right of center on the detector, then the outcomes for a ‘which slit’ measurement that are left of center are 100% from Slit 1, while those that are right of center are 100% from Slit 2. As you move the detector continuously farther and farther away from the slits, the probability that a photon detection left(right) of center is due to Slit 2(Slit 1) gradually increases until the detector gets to the ‘interference’ measurement location where the probability that a photon detection event left(right) of center is due to Slit 2(Slit 1) is 50%. That is, a photon detection event for the ‘interference’ measurement left of center is equally likely to be associated with Slit 2 as Slit 1 (vice versa for right of center). This is qubit superposition for the double-slit experiment.
In conclusion, QRP says that QM is telling us how Nature behaves in accord with the relativity principle and Planck’s constant h, just like special relativity is telling us how Nature behaves in accord with the relativity principle and the speed of light c.
From a non-physicist, minimal math POV, physics at =< molecular scales seems to involve "areas of energy" that have only functional boundaries when considered as parts of systems, or collections of those areas of energy. In other words, no "particles" as balls of stuff, but "entities" of predictably variable areas of influence over and with other entities which are governed by energy/force, type/state.
this is not wrong per se, quantum states tend to share and distribute their properties in a relaxed kind of way, and only when they are vibrated by their environments to they collect back into bounded particle like states
Nice comment. I think science teachers really should drive this point home to students. I don't think many do. . Right, an energy wave is in a 3d volume area, with continuous intensity (amplitude) changes throughout this volume, thus making it an wave of energy. A lot of students are led by teachers to conceptualize this as a 2d pattern and get confused. Why do so many teachers do this? I mean, what we are talking about here isn't a science basic, it's a fundamental. Can you imagine if jet pilots taught flying fundamentals half ass? Jets would be crashing all over the place. That's the thing, flight instructors can't get away with half ass douche bag teaching. Science teachers can, and many do. Especially many teaching in American high schools. I wrote more as a comment to dhudach above, if you are interested. Thanks for the comment.
And that´s why superdeterminism is the way that future research should go.
That intro !! 👏👏
One of your best videos, imho!
Thanks for your work, Arvin!
Reality is rendered to conscious beings on the fly, based on probability. But it has to be consistent with information that already exists in the system
The pattern you show at 7:34, the two bands, never happens with photons. If you determine the which way information the double slit interference pattern will disappear, and it will be replaced by a single slit interference pattern.
As someone who uses statistics in their profession on a daily basis, quantum mechanics became less mystical after this video. I like the idea of things being in two places at the same time though. It makes for good sci-fi.
Would love a video on the ontology of spacetime
I describe it in reference to the vertical line test of graphing to see whether or not something is a function or not. If it fails the vertical line test, it's not a function; it's quantum mechanics.
If you want to know where the particle actually is, you gotta go through the tedium of walking the line to see where it is.
My dog ate my homework
=
A particle exists in all possible places🤏
GREAT, CLARIFYING EXPLANATION!!!