Quantum Measurements are Entanglement

[@EugeneKhutoryansky]

To see subtitles in other languages: Click on the gear symbol under the video, then click on "subtitles." Then select the language (You may need to scroll up and down to see all the languages available). --To change subtitle appearance: Scroll to the top of the language selection window and click "options." In the options window you can, for example, choose a different font color and background color, and set the "background opacity" to 100% to help make the subtitles more readable. --To turn the subtitles "on" or "off" altogether: Click the "CC" button under the video. --If you believe that the translation in the subtitles can be improved, please send me an email.

[@jezzamobile]

Cat watching! Excellent 😸👍

[@darkslayer175]

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

[@EugeneKhutoryansky]

Thanks for the compliment.

[@mountainhobo]

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'. :)

[@zes3813]

wrr

[@Qman621]

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

[@RadioReprised]

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

[@EugeneKhutoryansky]

If you like this video, you can help more people find it in their KZbin search engine by clicking the like button, and writing a comment. Thanks.

[@omniyambot9876]

I learned so many things from your videos. You're the best youtube video maker. How did you know those things? What's your job? Hope you reply :)

[@John77Doe]

Physics Videos by Eugene Khutoryansky Do you have a Patreon account where viewers can fund you?

[@aadarshasubedi123]

Mr. Khutoryansky and Miss Kira Vicent are always welcome because u both help me in Fourier series which was outstanding than all of other's because it was unknown to us that it can be shown in 3d. ..Thanks a lot...

[@EugeneKhutoryansky]

John Doe, yes I have a Patreon account where people can help fund my videos. The link is in the video description up above, and on my KZbin home page. Thanks.

[@StephenGillie]

The insights provided here are tremendous. I wish I could like it twice.

[@adawg6162]

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.

[@TheZenytram]

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.

[@EugeneKhutoryansky]

Thanks. I am glad you like my videos.

[@RolandMoone]

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.

[@EugeneKhutoryansky]

I also wish that more people knew about my channel. Thanks.

[@EugeneKhutoryansky]

You can help translate this video by adding subtitles in other languages. To add a translation, click on the following link: kzbin.info_video?ref=share&v=sFRdVj4rrAE You will then be able to add translations for all the subtitles. You will also be able to provide a translation for the title of the video. Please remember to hit the submit button for both the title and for the subtitles, as they are submitted separately. Details about adding translations is available at support.google.com/youtube/answer/6054623?hl=en Thanks.

[@AlexHop1]

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.

[@nmarbletoe8210]

Mind. Expanded. thx

[@LeMarocain98]

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?

[@EugeneKhutoryansky]

The "many worlds" interpretation of quantum mechanics proposes that the wave function never collapses, and that we too end up being in a superposition of two different states. In this view, there would be two different versions of you, each of which saw a different outcome. The two different versions of you would never be able to interact with one another.

[@brunlelo]

The way you put this, made so much sense to me about the "many worlds" interpretation now. It's not the conscious observer that colapses the wave function, the thing is that the conscious observer is the only observer that is aware of what outcome he is being part of. We can't colapse the wave function, we just can't see the whole of it. If a conscious observer could keep his "conscious part" connected throughout the wave function of the universe, he would be able to see all of the possibilites happening.

[@WeShredForBeer]

Physics Videos by Eugene Khutoryansky holy shit this sounds amazing :O. Can you also do a video on string theory? I really never got this...

[@PumatSol]

Physics Videos by Eugene Khutoryansky It seems to me that if we accept that superpositions are "real", and that each possible state of a system is equally "real" until we observe it and become entangled ourselves, then we must also accept that when we do observe it, our state at that point is just as “real” as the state where we observed a different outcome. Unless we assume that we are special, I see no reason to believe that a human observation would “collapse” a wave function any more than any other interaction. What are some challenges to the many worlds interpretation?

[@john_air]

Bruno Lelo you can have that experience by doing meditation

[@amoses7178]

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.

[@EugeneKhutoryansky]

Thanks for the compliment about my videos.

[@das_it_mane]

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

[@EugeneKhutoryansky]

I am glad you like my explanations. Thanks.

[@MrHatoi]

Absolutely love the part with Cat's Schrödinger

[@OTrajano25]

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

[@EugeneKhutoryansky]

Glad to hear that my videos are useful. Thanks.

[@OTrajano25]

Taking the risk of being a personal point intruder, could i know what is your achademic degree and the area of study? One reason for being so useful could be my way of processing information. I find it a lot easier to understand and connect ideas and concepts if i can somehow give them a mental 3D image, even if only a metaphoric one. And i can file my mental lacks through your graphical simulations.

[@feynstein1004]

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. :)

[@EugeneKhutoryansky]

More videos are on their way. Thanks.

[@AllbyMath]

This is the best video about decoherence which doesn't even mention 'decoherence'. All my respect!

[@EugeneKhutoryansky]

Thanks.

[@corey333p]

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!

[@bonniedean9495]

Good video, one of the best!

[@EugeneKhutoryansky]

Thanks for the compliment and I am glad to have you as a subscriber.

[@fakherhalim]

Unlike quantum uncertainty on extremely small particles, I am 100% sure that Eugene videos (and contrasting explanation) are the best know to me! They make otherwise blurry quantum mechanics concepts crystal clear!

[@salvatronprime9882]

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

[@darkfinderer]

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.

[@cubing7276]

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.

[@jessemontano762]

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

[@parjohansson3118]

Another beautiful visualization. Clear and to the point.

[@EugeneKhutoryansky]

Thanks. Glad you liked it.

[@stephenkamenar]

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

[@rollingrock5143]

Now my weekend is complete, or not.

[@teedjay91]

let me observe that, you will be fixed.

[@serializer7274]

Excellent, thanks! Quantum related videos are my favourite.

[@EugeneKhutoryansky]

Glad you liked my video. Thanks.

[@adelarscheidt]

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

[@GuyDavisable]

In the KZbin comments? :P

[@gbBaku]

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

[@sserugoenock46]

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

[@EugeneKhutoryansky]

Thanks for the compliment. More videos are on their way.

[@RubberJunk1]

Cant wait to get a takeaway and watch this.

[@DarkePacific]

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

[@EugeneKhutoryansky]

Thanks for the compliment.

[@psmusic7565]

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

[@EricShaw1337]

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.

[@seanwiesen7418]

Fascinating video. Thank you for explaining this so clearly.

[@EugeneKhutoryansky]

Glad you liked my video and my explanation. Thanks.

[@alasdairdew]

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

[@michelecariveau3973]

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

[@EugeneKhutoryansky]

Thanks for the compliment.

[@benjaminbrady2385]

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

[@EugeneKhutoryansky]

Thanks.

[@sinant.1121]

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

[@EugeneKhutoryansky]

I am glad you liked my video. I may eventually make a video about superconductors. Thanks.

[@taitywaity1836]

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

[@EastingAndNorthing]

I always watch these at 1.5x speed ;)

[@gbBaku]

Wow why hadnt I thought of that? Thanks for the tip!

[@justinmallaiz4549]

same here, (and most other videos) I wish they had 1.75x speed in stead of 2x. :)

[@feynstein1004]

Me too. :)

[@insideoli]

ghaaa dang i hadnt thought of that silly me! thanks!

[@stlkngyomom]

Try 2,double physics in half the time.

[@geekyourlikeslulu]

Best explanation ever thank you so much!!

[@EugeneKhutoryansky]

Thanks for the compliment. Glad you liked my explanation.

[@pendalink]

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

[@full__tilt]

Can we have the sexy angels back?

[@EugeneKhutoryansky]

They may return for a video on "Maxwell's Demon", as this is who the girl with the horns was meant to signify.

[@4BFF9]

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

[@MarkusOdds]

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.

[@GreatWhiteNiko]

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!

[@EugeneKhutoryansky]

Thanks. I am glad you like my videos.

[@spyle2]

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!

[@EugeneKhutoryansky]

Glad you liked my video. I'll think about using other transitions. Thanks.

[@jamest.5001]

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.

[@insideoli]

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!

[@itzchi]

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 KZbin that makes PHYSICS so much fun and the concepts easy to understand. Please keep up the good work.

[@EugeneKhutoryansky]

I did not say that no observer is required to collapse the wavefunction. What I said was that no observer is required to make the stripped pattern disappear. Even after the stripped pattern disappears due to the presence of detectors, you can still have the superposition of possibilities behind the left hole and the possibilities behind the right hole. And thanks for the compliments. I am glad you like my videos.

[@overman6563]

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.

[@SmigGames]

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

[@a000ab]

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 🙏

[@Domispitaletti]

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.

[@mahmoudnafousi2427]

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 [e-mail]

[@davidwright8432]

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!

[@JuiceBoxWizard]

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.

[@xenofonz7640]

Observer or not the cat is not a quantum "particle" and so the cat is either dead or alive at any given time. The cat will die eventually unless you believe in immortal cats. It's a thought experiment to try and explain QM using normal every day objects. It doesn't really mean the cat is dead and alive at the same time. Otherwise, one could say that after flipping a coin the result is head and tail at the same time until someone looks at the result, which is silly.

[@JuiceBoxWizard]

I was using the language of the thought experiment to explain my confusion without going into unnecessary detail.

[@xenofonz7640]

Understood. In that case we enter a realm about the interaction between the observer and the QM world in various complicated ways. Heisenberg's Uncertainty Principle provides to best and most complete scientific approach thus far to explaining how a Quantum “particle” can have a range of values for its position and momentum in superposition. This is governed by the equation ΔxΔp ≥ h/2π. Thus the range of positions can be relatively small while the range for momentum can be relatively large, or vice versa but never both being small enough to give a near precise enough position and momentum. Also, when we “observe” the exact position or the momentum of that “particle” the wave function collapses (ie, no longer have a superposition of various states) and we get a precise and correct value of the position or momentum associated with that “particle” but never both. Let me explain. If we observe the position of the “particle” and thus determine its precise location, the momentum we subsequently observe is not the same as the momentum at the time of observing it’s precise position. Likewise, if we first observe the momentum precisely then we observe its position, that position is not that of the “particle” at the time we observed the exact momentum. Please note I have not discussed the actual method of measurement. Heisenberg's Uncertainty Principle is not about the measurement per se but simply about the position and momentum. That’s a subtle but very important difference. The actual method of measurement, say by using electrons or photons to locate the position is a separate discussion topic in itself and has nothing to do with Heisenberg's Uncertainty Principle. In that case the act of observing in the above thought experiment is not about measuring but about determining the position or momentum without physically measuring anything using say another “particle”. The act of physical measurement will introduce additional consequences to the experiment beyond what Heisenberg's Uncertainty Principle describes. This is the part that most people misunderstand. I hope this helps.

[@naturegirl1999]

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

[@hr4f774]

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

[@hussiendaeeh]

You have all my respect and appreciation, thank you.

[@EugeneKhutoryansky]

Thanks. I am glad you like my videos.

[@JayaSharma-zh3ly]

sir could you please upload videos on use of Laplace transformations

[@tasman655]

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

[@bloggervista]

Wow Long Time And a Great Video :)

[@RiadhBoukratem]

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.

[@AbdulAzeez_9]

Thumb's up for your continues work🙋

[@EugeneKhutoryansky]

Thanks.

[@bumpty9830]

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...).

[@tennenrishin]

Should have turned the cat green also, when it observed the green (and not yellow) entangled particles.

[@RohitSharmaRH_61]

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.

[@EugeneKhutoryansky]

Glad you liked my video. The music is from the free KZbin audio library, and it is called "Stale Mate." Thanks.

[@DudeWhoSaysDeez]

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?

[@synx6988]

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?

[@xenofonz7640]

In the real world an observation would require some type of physical interaction with the subject of observation. When that happens the assumed superposition of states "collapses" and we literally observe only one sate. Another observer would then come along but the object would of course already be in one state (known to the first observer but not the second) - however it too will be impacted by the physical means of observation and alter that known state to another known state (hence the state that was.known by the first observer is no longer valid from his/her point of view). We can ping pong or include other observers and as you can see it always changes. However all the observers can be informed via other means (eg, email) what the last known state is at any given time. It gets more complicated when you include relativistic effects but let's not go down that road. The real question that is in contention is what is happening BEFORE the first observer makes the physical contact? Is the superposition of states real (ie, the object in question is really in multiple states at the same time - like the thought experiment with Schrodinger's cat) or it is already in a single state to begin with but we do not know what it is and we can only surmise that it's in one of a number of probable states governed by the wave function? That's where the real debate is held. There is no way at this time to answer this dilemma since in order to prove it one would have to make the observation WITHOUT physically observing the state(s)- something that's impossible at this time. Please don't go down the road of delayed choice quantum eraser experiments and the like as they really don't prove anything definitively. They can be explained away in a number of different and conflicting ways so they are not definitive in resolving the issue. I know as my background training is as a PhD physicist (in other areas) and have studied the subject matter for a long time now. It's a fascinating subject indeed. It gets more complicated when you include Heisenberg's Uncertainty Principle (see my comment below). When that's included the known state is no longer actually real! It's only ever an approximation especially in the Quantum world. It becomes more accurate when the objects get larger and in the macro world (ie, objects we can see with our eyes) then the accuracy of measurement is such that it's so close to the real one even with Heisenberg's Uncertainty Principle that for all intents and purposes they are the same. I hope I've made myself clear.

[@joshuayong1431]

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...?

[@riccardofasano1040]

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...)

[@EugeneKhutoryansky]

Thanks for the compliments. I have a video that addresses in detail the mathematics of observables, operators, and eigenvalues at kzbin.info/www/bejne/govMlmWHeJp9mMU

[@johnmcntsh]

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

[@GaugeMcArora]

you people are great thank you soo much

[@EugeneKhutoryansky]

Thanks for the compliment. Glad you liked my video.

[@Marinealver]

When you think you understand quantum mechanics, you don't understand quantum mechanics.

[@mikkel715]

Thanks to KZbin and Eugene. You don't need a PhD to not understand Quantum Mechanics.

[@akira1228]

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 :)

[@EugeneKhutoryansky]

I already have a video titled "Delayed Choice Quantum Eraser" at the following link. kzbin.info/www/bejne/iaukgmZsl56XsNU

[@akira1228]

+Physics Videos by Eugene Khutoryansky thanks :)

[@WackyJackyTracky]

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.

[@lepidoptera9337]

Newer? Examples of such processes were already given by Heisenberg and Mott in the 1920s. They didn't use the modern terms, of course, but the basic ideas were already there.

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?

[@Kowzorz]

I love the cat in this so much.

[@aadarshasubedi123]

although this is unrelated for me I always watch for your voice...that's nice..

[@EugeneKhutoryansky]

The voice is from my friend, Kira Vincent. She does the narration for all my videos.

[@MrAntieMatter]

I always thought it was text to speech.

[@nmarbletoe8210]

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.

[@Jopie65]

When you don't observe the person observing the experiment, does that mean the observer and the experiment are now entangled and in super position for you?

[@Legionsale]

Отличная ирония с котом Шрёдингера)) Кот, наблюдающий за людьми)

[@PremVijayVelMani]

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.

[@mikkel715]

It is inherently uncertain at what point in time a quantum observation is definitively defined.

[@dieterheinrich8377]

I'm trying to understand how this is more than some kind of word play going on. What if I argued that "possibilities" can exist simultaneously (in our minds), but the thing-in-itself still only has one actual state. It is the "possibilities" of Schroedinger's cat being alive or dead that both exist (superposition), but as far as the actual cat is concerned, it is already one or the other. We just can't know which. So we invent the concept of superposition as a way of keeping possibilities in play, allowing us to plug 50% or whatever into our equations, until we can make an observation that "collapses" the possibilities, the wave function, into one actuality. How is this more than just a fancy obfuscating way of saying, "Now we know"?

[@innertuber4049]

So the four numbers representing spin or polarization outcomes are the reason why quantum teleportation requires 4 bits of speed-of-light information to work?

[@martijnbouman8874]

Regarding the question the video ends with: Why would the system ever collapse to just a single possible outcome? Isn't us observing one of the particles in the system equivalent with us becoming entangled with the system as well? That would, at least, seem pretty logical to me.

[@xiitux18]

Martijn Bouman the traditional explanation would be that what you measure is the real thing, so only one outcome/final state can exist. But you can argue that there are actually two states in a superposition: you observing one outcome or the other.

[@matthewai32]

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.

[@EugeneKhutoryansky]

It depends on what exactly the author of that article meant. If he just meant that the detector by itself is able to cause the stripped pattern to disappear, then this is correct and consistent with what is shown in this video. However, if he meant that the detector by itself is able to collapse the wave-function, then this is just an opinion, and there are many opinions about this. If you haven't already seen it, I cover the various points of view on this in my recent video at kzbin.info/www/bejne/joKVZnhvnNpnp6s

[@matthewai32]

@@EugeneKhutoryansky Thank you so much. I will check out that video. Love your work!!

[@jaideepkhare5903]

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 😃

[@realcygnus]

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.

[@theosib]

I think in reality it must matter how many particles are in the detector. It is entanglement with or absorption by something macroscopic that causes the decoherence.

[@lepidoptera9337]

Nature is rolling on the floor, right now.

[@M_1024]

Where was this video my whole life?

[@mikkel715]

It came in as a Delayed Choice. Before you didn't miss it your whole life. Now you have missed it your whole life. Best Regards: - Quantum Mechanics -

[@M_1024]

@@mikkel715 I missed it for part of my life

[@omsingharjit]

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 ?? 🤔🤔

[@mikkel715]

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.

[@EugeneKhutoryansky]

Thanks for the compliment about my video. I have a video discussing the various interpretations of Quantum Mechanics at kzbin.info/www/bejne/joKVZnhvnNpnp6s

[@sethcatalano6352]

Aren’t we just collections of particles, so a collapsed state is relative to an observer?

[@vshah1010]

Not sure that I agree with the conclusion drawn. That the 2nd particle is entangled with the 1st particle. I see the 2nd particle bouncing off the first particle. It's interaction, but not entanglement.

[@SvenBerkvensMatthijsse]

The thing is that by looking at what the properties (e.g. speed, direction) of the second particle are, you can infer things about the first particle. They interact and therefore become entangled.

[@vshah1010]

One particle hitting another particle is not entanglement. The two particles have to "match" for it to be entanglement. In the first example given, It is more like a billiards table.The other particle moves in a direction determined by how the first particle hit it. The 2nd particle interacts with the 1st particle. Entanglement is when the 2 particles have (usually) opposite spin, and maintain that spin. That's the definition of entanglement. The video does show two entangled particles spinning in the next example. The first example given is not an example of entanglement.

[@wesjohnson6833]

The 2nd particle interacts with the superposition of the first particle and so it too is in a state of superposition , one interacting with the particle from slit 1, the other from slit 2. Each interaction is also an entanglement because either movement of particle 2 is dependent upon particle 1. They are not independent events, but in fact maximally dependent, hence, entangled.

[@fredfredricksen2616]

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.