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The moment video started I cracked up and thought, 'brilliant, the revenge of the Schrödinger's cat -- now he decides what is real, and what is not'. :)

Yet again incredible work. I wish more people could describe physics(particularly quantum mechanics) with as much clarity as you do.

I really appreciate all the work done to make these animations, it helps tremendously to try to wrap my head around this concept.

My shirt says''Man!......You just collapsed My wave function!''

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I had never thought to consider the double slit from the perspective of deriving the complex coefficients of the various wave functions. This is phenomenal.

I wish more people knew of this channel. The length of the videos seem daunting, but the level of depth is covered in such great detail. I love that you cover everything step-by-step and never gloss over any small details. Also, the long videos + the music make for great bedtime stories.

man, in a span of a year till this video you did 41 videos, that is insane, with explanation and animation so clearly that any lay man can understand, this year must have been a hell of a year :) thank you for making this channel.

Amazing video. And I guess congratulations are in order for the soon to be 100K subscribers. Keep up the good work. Can't wait for more videos. :)

One of your best videos! Love it! Been waiting for it for a long time. =)

This is fascinating stuff. I have a question. What if the whole universe was all entangled together so the wave function never collapses at and all possibilities always exist simultaneously, but when we observe the outcome, the particles constituting our body also become entangled in a way that our consciousnesses only perceives a certain reality and therefore conclude falsely that the wave function has collapsed to one possibility? I know it's only an interpretation, but is it allowed by the mathematics of quantum mechanics?

I've never seen the double slit experiment explained in this way. Very clear, makes more sense than the many explanations I've seen elsewhere. Thanks!

your work only keeps getting better. never stop! also id like to see a video on the curvature of space-time near a black hole and the information-loss paradox

These videos are so important to help in understanding. Even after all this time, I've rarely found anything that even comes close to helping with understanding as well as your videos and explanations.

I like the role reversal of Schrodinger's cat =^.^= ha ha!

I can't believe how clearly these videos explain these topics. Thank you for making these!

Good video, one of the best!

Another beautiful visualization. Clear and to the point.

Cant wait to get a takeaway and watch this.

Fascinating video. Thank you for explaining this so clearly.

Excellent, thanks! Quantum related videos are my favourite.

I asked Dr. Ruth Kastner, a quantum physicist about the point that Eugene makes in this video. This video has been eating at me for two weeks while I puzzled over it! I asked are there 2 different kinds of quantum interactions and 2 different kinds information formed by these 2 types of interactions. She wrote, "And yes indeed, there are two main types of interactions. The kinds of interactions that can create entanglement (or can take place while retaining entanglement) are those involving only force-based connections, i.e., which occur at the virtual particle level. In contrast, the kinds of interactions that break entanglement and lead to ‘measurement’ involve energy transfer, via real (as opposed to virtual) particles. This is discussed in Chapters 4 and 5 of “Understanding Our Unseen Reality,” but I’m working on a follow-up book which hopefully will make this issue more clear." Dr. Kastner is referring to her book on the Transactional Interpretation of quantum mechanics. She has played a role in developing this interpretation, which was originated by John Cramer based on the Wheeler-Feynman absorber theory.

I have never seen such well explained Physics animation Videos...So thank you so much Eugene...May GOD bless you to make more....

You've really had those subs increase awesomely..... You deserve it man..

you blew my mind, once again :) thank you!

Wow Long Time And a Great Video :)

This really has been the best explained video i have ever seen from you!!! :D I really understood everything, i really liked how you represented those particles bumping with other static one without interacting with the other set of possibilities in the green particles! I think that us, made of the same particles in the universe, in fact, doesn't mean we can change the outcome, neither of us can either, so... does that mean we change the set basing on what we observed and processed by our own brain? and that other person can see other information different on what we observed? who is right? could we possible be in the superposition of both realities were we see things and see the other outcome at the same time but collapses by the given information from another human? that could be a great experiment to do so!! what would happen if we experiment to lie to the true outcome? would that change the reality based on what we were told? anyways i LOOVE this topic!!! and i loved how you showed us the mathematical representation of quantum entanglement! i'd love to see some examples also why not? some other examples and variables of this experiement, for example, when the detector is right before is hit in the wall and things changed and makes it to the other hole and time goes bakwards? i don't think it would happen, i guess it just collapses in the other possibility and becomes true the other one i hope my english isnt too bad THANKS FOR THE VIDEO!! I ALWAYS LONG TO SEE MORE!

Absolutely love the part with Cat's Schrödinger

Great Stuff, dude. Do you take requests? Differential Equations, please!

P.S. Excellent descriptions, your videos are great :)

Thank you for this amazing Video. I hope you make a Video about superconductors.

I'm a physics undergraduation student and i use your videos to clarify and deeply understand the concepts of the lectures. Thank you.

I was obsessed with the meaning and the philosophical implications when I saw the quantum eraser experiment. I rejected the idea of a conscious observer being the reason for the particle behavior but with a superficial knowledge of QM math and concepts, understanding entanglement and complementarity was out of reach. Read articles and watched videos but it wasn’t until I watched yours that I made some sense of the experiment results and now I know that any level of real understanding can only be achieved through math. Thanks a lot.

great video. even if I don't really understand. but hey that's why I'm watching! to learn. they needed videos like this when I was in school.

Now my weekend is complete, or not.

Best explanation ever thank you so much!!

Really appreciate the work done for this video (and for the whole playlist), as always Eugene is great at making visually understandable concepts which seem so abstract. I was wondering if anyone here knows where can i found something which is more mathematically consistent, since I'm trying to figure out the link between this visual understanding and the math behind it (such as observables, linear operators, eigenvalues...)

I remember finding a website that says something like this: There's a particle in the lab and Alice takes a spin detector to measure the spin of the particle. Bob is outside the lab and sees Alice measuring the spin in the Z direction but he couldn't see what the results are. Alice concludes that the particle is "spin down" while Bob concludes that the particle's spin is entangled with the detectors and Alice herself.

+Physics Videos by Eugene Khutoryansky Where can I find these considerable philosophical debates?

Thumb's up for your continues work🙋

I used this channel, as well as similar channels, to practice focus and improve memory. Very few educational videos can be used for that purpose. Without going into details I can say that the pace of the narration, the smooth transition from one point to another, and the presentation of an exact amount of essential information is a very important part in actually benefiting from the learning experience. These videos are an excellent example of that! Thank you! Keep up the great work!

I always feel so enlightened after watching your videos. I wish I got the grades to study physics as a degree :(

when the cat looks at the bouncing balls, the cat gets entangled too and turns into a green cat and yellow cat

I was waiting for your video. It always refines my understanding about physics. Thank you Could you please tell me where I can find the background music you have used in the video.

you people are great thank you soo much

sir could you please upload videos on use of Laplace transformations

28:34: '... particles interacting with each other don't qualify as an observation'. My understanding is that precisely because 'particles interacting' DOES qualify as an observation, no 'conscious observer' is either needed (for an observation in this sense) - or adds anything not obtainable by interaction with a single particle, if present. Eugene, Please clarify. thanks!

I always watch these at 1.5x speed ;)

Eugene explains quantum mechanics so clearly and simply. It's amazing.

about the start.. the thing that strikes me about the double slit experiment isn't that the 2 possibilities happen at once, it's that those two possibilities interact with each other after the decision has been made. so surely when you show those two possibilites happening at the same time, they should necessarily bounce off each other even if the particle is one that's in the other state, for it to be a complete description

From watching your other video I had this question in my mind that if we place detectors on the gates but after doing the shoots we first observe the curtain without checking the detectors, will it be that we will see striped pattern on the curtain and once we check the detectors' recorded results, the striped pattern will immediately change to the pattern related to the particle passing from one gate at a time or not. I am so happy that you answered that question in this video. Thanks 🙏

Question, can you do a video on we measure spin/color/charge of particles?

In the beginning of the video you say it is a common misconception that observation is simply the act of two particles interacting. Well sure it's not so simple, but an observation is measurement, and measurement is entanglement. You can't have an observation without an interaction. That is why observation affects the results. The way you're using the word interaction is ambiguous, is it the second particle in your animation? or the particles the cat uses to measure one of the two particles? The details of how the observation is made is kind of important. Otherwise, you'll get people saying things like "Consciousness causes collapse" or that quantum physics somehow proves their new-age religion.

Really love your videos, they help me learn Physics a lot better as a visual person. I do have something to disagree with though: At 27:12, the video said that the appearance or absence of the striped pattern has nothing to do with whether a conscious observer is watching. However, it seems to me that: 1.The barrier interacts with the particles and becomes entangled with them. 2.The conscious observer observes the presence/absence of the barrier. 3.Thus by observing the presence/absence of the barrier, the conscious observer collapses the barrier-particles system from a superposition of (striped,barrierless) and (unstriped,barrier) into either state. Thus it would seem that the conscious observer still determines the appearance or absence of a striped pattern...?

You have all my respect and appreciation, thank you.

In Quantum eraser delayed choice video you showed that only measurement does not collapse the wave function. It's the observation that collapses the wave functuon. But in this video you say that no observer is required to collapse the wave function! Can you please explain in detail? BTW, great video! You channel is one of the best channel on KZfaq that makes PHYSICS so much fun and the concepts easy to understand. Please keep up the good work.

I really enjoyed the video. One thing that I would suggest changing would be to use another transition than the flipping box. It's disorienting and uncomfortable. Thanks for the great videos!

In practical how do we detect the spin of the particle or, from where did it pass through (The Quantum Eraser Experiment). Your videos are Awesome.Amazing work.Soon to cross 100K 😃

The cat was such a great (and cute) way of showing measurement

Great video as always, but i think you should explain the difference between observation in the lab and whats happen in the universe, because i bet many people will think that you need A HUMAN looking to some point of the universe in order to produce decoherence, for example.

For a long time, I have been wondering the following, maybe you or someone else can answer this: What exactly is a detector (e.g. in your visualization)? In reality, I think every particle is interacting with each other particle in the universe for example through electric forces or other forces. And a detector seems to be just a bunch of particles that make it specifically easy to draw conclusions for human observers. This seems contradictory to you saying that observation does not play a role in the double-slit experiment, since, if there were no detector-particles, there would still be other interacting particles with the only difference that it would be virtually impossible for humans to conclude something out of the interaction of e.g. an electric force that the particle had with an object 5 meters away. It seems to me that only the probability of the concious observer being able to conclude which slit the particle took determines the inverse probability of seeing a interference pattern - and the presence or absence of a detector is just an element in a long chain reaction of probabilistic wave functions, which form our reality. But that's just me guessing, I'm nowhere near an expert in this field. To me it seems that this is more than a philosophical debate. What if you try to build something like half-detectors, which work less reliably in this sub-atomic scale? Would the probability of seeing an interference pattern increase? You could try to find out experimentally what qualifies as a detector. Have people tried this?

both "possibilities" exist, not both "trajectories" exist, thank you for not making physics look stupid like many ppl do whenever talking bout quantum mech... also, a door doesnt become an elephant when u stop looking at it ,its just that other possibilities for the state of that door pop up and you are unable to 100% prove some of them wrong unless you look at it

The most read article in Quora on the Conundrum of Entanglement as of Friday 6th Feb 2018. Below is brief summary. For the full details click on the link below. Entanglement: When two Subatomic Particles share the same Spacetime code they become entangled. As experiments have shown that two entangled particles act as one system as if they are communicating with each other instantaneously. If this is the case, then it’s reasonable to conclude that the data stored in the Cosmic Database are indexed in accordance to their “Spacetime codes”. So any update to one record leads to updating both records. Based on this postulation, we suggest that any change in the “Cosmic record” of an entangled particle must lead instantaneously to a change in its observed physical quantum state. It also lead us to conclude that the act of entanglement is necessary for the conservation of momentum, symmetry and and other relevant information. These suggestions support the possibility that we are living in a Holographic Universe. The Measurement problem: The observed wave functions of Subatomic particles are due to the nature and characteristics of two Basic Energy Particles responsible for their existence. The particles at the quantum level could be in any one of several states until they are measured. The act of measurements leads to their recognition in terms of cosmic information in that specific state at a given cosmic second. In the double slit experiments, to explain the collapse of the wave function we speculate that as photons interact with the observed electrons. They instantly share the same “Spacetime code” which make them entangled. Once an observer capture these photons (in the act of measurement and recording of the data) a new space time codes are given to the photons. This leads to the cessation of the state of entanglements as the photons no longer have the same spacetime code of the observed electrons. In response to erasing the act of entanglement, the observed electrons reset themselves by getting their energy cloud collapsing in readiness to start a new cycle of spins.This is done to preserve the law of supersymmetry. Consciousness and data recording: It is suggested by some physicists that the act of observations through effective meditations lead to the collapse of the wave functions. We speculate that such trained meditators are able to concentrate, capture and register the information carried by the entangled photons in their memories. This act of recording by the meditators constitutes particles interactions similar to capturing the data by measuring devices. Such interactions lead to the resetting of the relevant entangled pairs, hence the collapse of the wave function. This makes us an interactive players in the quantum information collected and recorded. docs.google.com/document/d/1qpnegrI9ox0gBRnN-jvA0PXHgcbpAdhwwpS__eBocq8 Mnafousi@gmail.com

I believe the observer becomes himself entangled with the particle. So to a second observer who does not observe the first observer or the particles the first observer is also in superposition just like the particles, that is until the second observer observes the first observer or the particles. The many-worlds interpretation makes most sense to me.

In your initial description you stated that an observation causes the superposition to disappear and an "observation" can only mean a conscious observation. The entire deductive chain of this video is based on this (correct) assumption.

Brilliantly presented. Bravo. What counts as an observation (for a particular observer)? The quantum entanglement of said observer's body with the information-bearing particle(s). This argument is better grounded in the Many Worlds interpretation than in Copenhagen, but if you're inclined to pick a moment of wave function collapse, you won't find a better definition. My favorite aspect of this interpretation is the beautiful parallels to observer-knowledge paradoxes in relativity. Did the two particles arrive at the same time? Depends on your reference frame. Is the cat currently alive or dead? Depends whether you're in the box with the cat (and with sufficient protective gear...).

Could you describe on the one of next videos the "Quantum Eraser"? I watched this topic on PBS Space Time before, but your videos usually are more understandable for me. Best wishes :)

Good Work!

My question is if one entangled particle can effect its twin particle . So what will happen when we create pairs of entangled particle and separate one particle and drop it in side of blackhole singularity ! After that will first particle from earth can able to communicate second particle ( twin particle ) or not ?? Because it is said to be.. that event horizon of the black hole separate it from the entire universe completely !!! And also there is no time inside blackhole singularity because of infinite mass density so .... What will happen when we try to entanglement experiment in this condition ?? 🤔🤔

Awesome work

Hi Eugene, I absolutely love your videos. However, I've reached a conundrum. I just read article on Forbes by Ethan Siegel on quantum mechanics / Schrodinger's Cat (I can provide the link if you would like) which says that a *detector* in a quantum system can *itself* be an observer, which would mean that a detector is itself able to collapse the wave function of a quantum particle. To quote the article: "In reality... [t]he fact of the door or gate opening, and the mechanism controlling it getting triggered, is a perfectly valid observation. Throwing a Geiger counter in there, an instrument which is sensitive to radioactive decays, would count as an observation. And, in fact, any non-reversible interaction that occurs within that system, even if it's completely sealed off from the outside world in that box, will reveal one and only one definitive state: either the atom has decayed or it has not." So my question to you is, do you think this article is perhaps wrong or misinformed? It seems to be at diametric odds with the information you present in this video-you say that a detector in a quantum system cannot be an observer and will actually become entangled with the quantum particle that it interacts with. Or maybe, perhaps this is all secretly a debate about philosophy, sentience, and solipsism in disguise? :-P I would really appreciate your opinion. Many thanks.

Basically, since the change in momentum in one object can be measured, we determine the position of the second object but NOT its momentum

I've always wondered what counts as an observation or observer. I always thought "wouldn't Shrödinger's cat still be dead/alive if we never checked? The cat would probably know, and different outcomes would follow (ie the box starts smelling like dead cat) depending on the outcome." Thank you for finally answering by letting me know that no one's sure exactly what counts.

Another great video. I want to know why the probability is square of the C variables. Only reason I find people saying is that it will avoid the problem of negative probability and normalising becomes easy but what is the exact reason.

superb content as always !.........imo a VR model is thE ONLY "sensible" interpretation for regular Quantum weirdness as well as retro-causality & such.........via the simple concept of "rendering".......It is true that interpretations alone don't necessarily add anything to sciences empirical knowledge-base. Ironically all progress in QM thus far was made with no "real" understanding except that the math makes accurate predictions(but thats ok).....but Combined with the fact that such model(s) also easily explain things in classical physics that "just are"......like the constancy of "c" as our plank length/pixel size divided by the refresh rate/outer time loop .....& charge, spin, mass etc as just #'s in a computer.....and entanglement as "if/else"/equidistant from source. etc.etc. I think the kernel/shell for a real TOE has arrived.

Entanglement is a natural spooky action, what is supersymmetric superpositions of locations and spin in same moment of the pair and anti-pair, particles-anti particles ( visible-pair and invisible-antipair quantum states). Or entanglement is a spooky supersymmetric visible-spin|invisible location and invisible-location|visible-spin pairs entangled in one entangled particle of the original particle, by its two wave functions in natural superposition, what they are attached in the same moment, the way that the information travel throughout the universe. Therefore. The message is time-dependent and it is light-speed independent.

I just found this channel and I'm sorry I didn't earlier. Wow.

Can we have the sexy angels back?

Easy to understand, thanks :D

Speaking to this philosophical side of this discussion: what is an observer? It's a great question because we humans are just groups of particles. So if anything, it's possible that our particles just become entangled to the experiment once we observe the experiment. It would then imply that our particles "know", and that us being entangled is what lets us in to peak at the superposition. Even if we observe it and no one else does, does that mean that we are entangled, but no one else is?

Quantum World is an amazing little place! Thank you for the precise and good video. Question: Are there QM interpretations having entanglement as extended delayed choice, but only to a certain degree of entanglement? Wave function collapse then makes reality. Superposition is somehow that nothing "did" happened yet.

2:12 = chaos magic and st francis of assis secrets

I really appreciate what you are doing with these animations. I am trying to understand what happens when I tap these keys to send this message. This is still QED with the electrons of my fingers interacting with the electrons of the keys. My experience of pressure on the keys, at its most reductionistic level, would be a Feynman diagram showing two electrons interacting by exchanging virtual photon(s) (that can have mass per Don Lincoln's video on QED or QFT). I don't grasp the nature of the interaction you show here. Are they the sort where photons "reflect" but are not absorbed. I don't see any exchange of energy in this story. I have always assumed that at least some interactions of "stuff" independent of human observation results in wave function collapses, exchanges of energy, and therefore experience. Bacteria are constantly sensing their environment. Their experiencing must involve wavefunction collapses, exchanges of energy. What am I not understanding? Thank you for your excellent work.

I think newer interpretations suggest different degrees of entanglement and decoherenace. So particles are not just like 100% entangleded or 0%, but can distribute their entanglement and step by step loose their coherance with interactions.

Thanks again for this wonderful and clear explanation again! My guess is that a superposition simply represents things that did not happen yet. It has the same properties of an undetermined future. As where the superposition 'collapsed' to one of the possible outcomes, it represents a thing that happened and has now become the past. Because the state has become 'fixed'. 'Many worlds' simply means the undetermined future in that sense. What are your thoughts about that?

I love the cat in this so much.

Please make a video about Keplers laws

The delayed choice quantum eraser helps to discriminate between a detector and an observer. My guess is that an observer needs a thermodynamic quality, ie a change in entropy (as measured in bits, as opposed to energy/temp.) Seems it is closely tied with reversibility and unitarity. Say the cat is now part of the observed system. Then, if we observe the cat, the outcome not a superposition. However, if we shoot the cat, and then observe it's remains, the outcome is still not a superposition, but if the cat is somehow causally disconnected from us before any observation is made, then I bet the superposition returns. We need a black hole to do some experiments. It's not consciousness, it's complexity/entropy that makes the difference between a detector and an observer I think. Any thoughts?

i like this topic !

Hi, I really enjoy your videos thanks for making them. You say that 'whether or not the striped pattern appears has nothing to do with whether or not a conscious observer is watching' but does the quantum eraser experiment not bring this statement into question? In the experiment the detectors are still in place so there is still an interaction, but the information from the detectors is scrambled and (amazingly) this causes the striped pattern to appear. The delayed choice quantum eraser experiment takes the quantum weirdness a step further. Or am I missing something here?

So mesmerizing.

The detectors could have an inductance or conductance which alters the result because of time. Add dimensional detectors one set for rotation the original for vector.

I need to know what counts as an observation. You say at the end that particles interacting with each other does not count. What is your basis for this statement? Also does it have to collapse to a single outcome for everyone at the same time? Doesn't it just collapse to a single outcome for whatever it becomes entangled with, while for the rest of the universe it will still be in a superposition until entanglement occurs?

Very best video. Could you please give more any animation video lectures of Bell's Inequality in youtube again ? Thank you very much.

but... the "observation" is also a particle hitting another particle in the detector. And we observers are just fancier particle detectors built of particles. Any way you slice it, it comes out particles.

So, without the detector, the two waves arriving at the same place interfere with one another. The two waves are treated as contributing to the same outcome, since from the outcome, there is no way to tell which slit the wave came from. But with the detector present, the detector differentiates the two waves, since it tells you whether the photon passes through one slit or another. Does the detector differentiating the two waves "produce" two more completely independent states out of the original two states? (The original two states actually had four states at first, but each state was a superposition of two states, until we could tell those two states apart through the detector). Could it be possible that the detector produced *dependent* states instead? Why is it that the two new states have to be independent of the rest?

How do we know particles are in a superposition of multiple states until measurement if we cant measure them without "collapsing" the superposition?

I know this is a complicated subject bu this video makes it more so.