The EPR Paradox & Bell's inequality explained simply

[@LydellAaron]

The understanding of this material doesn't really come from one video, it comes from watching a whole bunch of them, listening to all their perspectives, and then slowly merging together a coherent interpretation. It's very exciting! Thank you for producing your videos and adding perspective to this problem.

[@xyzabc12345jkl]

+upvote

[@ACuriousChild]

@ Lydell Aaron Yep, THE HUMAN MIND tries to simplify things so it can run with it trying to convince other HUMAN MINDS in order to "conspire" again its CREATOR. The analogy to it would be a PC (HUMAN MIND) trying to outsmart a Quantum Computer (GOD - THE THING THAT CREATED THE HUMAN MIND FOR HIS PURPOSE) You need the PC and the QC - but it should be clear by now which one reigns supreme! Which one IS still without the other and which one cannot exist without the other!

[@anderslarsson7426]

so it is not just me😊

[@1stPrinciples455]

And everything is just theory. Not proven to be absolute truth even the proving that Neils was right. Thats not an absolute proof. It just supports the Likelihood that Einsten was wrong. Also, entanglement implies info can travel faster than light. In fact, instantly in the absolute sense

[@1stPrinciples455]

Many videos talk about same things

[@chriskaplan6109]

continually stunned at his ability to take incredibly complex concepts and topics and make them accessible in a conversational and layman-friendly way. truly setting the standard for content in these genres.

[@armenstaubach9276]

You understand that he is taking other peoples note and books and none of these texts are his? And disgracefully he doesn’t cite any of them! But who gives a sh… in world where Trump becomes a president, Kardashians are know more than Tesla, why doesn’t this fake scientist be the hero of the day?

[@planpitz4190]

The most outstanding thing about this video by Arvin Ash is throwing in the explanation of the Mathematics in a way for the Layman to understand ...no other big media company Science show has ventured into this realm..not even the BBC .Congratulations!

[@ameremortal]

And he doesn’t need big words to make himself sound smart, his knowledge and intelligence is obvious.

[@Sid-69]

Tbh I didn't understand the maths. I wish Arvin could dumb it down more for peons like me :/

[@manan-543]

@@Sid-69 it was as dumbed down as it could get. I suggest you watch the math part again. And really focus on what he is trying to explain. I know you'll get it.

[@edwinbz9889]

The Layman lmfao the nicest way you can call somebody dumbo

[@edwinbz9889]

@k1w1 I maybe late man but I ain't no layman.

[@GlorifiedTruth]

"The universe has rigged the game against me." I've known this all my life... SIGH.

[@Alkis05]

Yeah, that certainly rings a bell.

[@thepenguin6225]

🤣🤣

[@asishmagham7948]

No it did not that's the whole point of the video

[@wj12]

Lol

[@stant7122]

The universe is last to act.

[@jackhill2765]

This is far and away the best explanation of Bell's inequality I have ever seen/read. Arvin has truly hit the nail on the head, not too hot, not too cold, just right. I actually think I understand exactly what Bell's inequality is all about. Thank you Arvin!!!

[@Puddymom]

Omg I finally get it. The sin wave diagram did it for me. I’ve been trying to understand it for a couple of years!

[@laserbeam002]

I have no idea what he said but I enjoyed listening to him.

[@jrausa1]

Bravo to the actors playing Alice and Bob. It’s very difficult to stand motionless in front of a camera for a long period of time and not lose focus / concentration.

[@henrymakepeace]

They are not real people, AI generated.

[@brendanfan3245]

good teachers make a huge difference, thank you!

[@beamantv9407]

Fans are neat

[@Velodan1]

I can tell Arvin takes his role of teacher quite seriously. Loved this video and the subject matter is always edgy. That is Arvin explains current accepted science as simply as possible with mysterious difficult to comprehend topics.

[@quantisedspace7047]

The first time I've seen an understandable explanation of Bell's Inequality

[@johnjay6370]

I have seen many of these explanations but this is the best. You hit a few key points that are always overlooked and those key points made it very clear. The meat that most explanations don't explain is at 14:47. That was the missing part that you nailed! Good Job!!!!!

[@ernestmoney7252]

The general rule for science instruction (including computer science) is that the instructor's rate of progress through the material is directly proportional to its level of difficulty.

[@stephenbrickwood1602]

@@ernestmoney7252yep, the level of the audience.

[@Puddymom]

Totally agree I’ve never seen that part before, now I get it.

[@Retotion]

Even after the Nobel announcement and all the videos that have come out recently, this is the only once I could find that actually mentions this part.

[@nicolasjonasson4820]

Agree, it is annoying when the instructor doesn't explain something very important (just watched another high ranked video) I find it impressive to be able to explain things like this to a person like me. I or course don't understand this theorem, but at least I now roughly understand the parts that makes up this puzzle.

[@augustofretes]

Bell inequalities do not disprove hidden variable theories. It rules out local hidden variables, but you can still have non-local hidden variables, like in pilot wave theory.

[@ArvinAsh]

Yep. I should have made that clear in the video.

[@marin4311]

Best video about entanglement I've seen .

[@danieltrump9110]

I repeatedly ignored your videos in search results and recommendations, but from now on you will be among the first ones I click. Great job!

[@headvodon2842]

This channel don't make me smash my head in wall like on other channels when it comes to science. Your way of explaining is good. Keep it up.

[@ArvinAsh]

Avoiding a science concussion is a good thing buddy!

[@PrayookJatesiktat]

11:12 because the Q axis is not independent of Z and X. How can you say all 8 events have an equal chance of happening (even in the hidden variable universe)? The hidden variable universe did not prevent Q from being dependent of Z and X.

[@wesjohnson6833]

See N. David Mermin for examples where ANY weighing of the probabilities still violates the inequality.

[@peterb9481]

A really good video. I liked Jimi Alkalili’s explanation on the episode Einstein’s Nightmare (obviously simplified similar reasoning). However I love this modern era we live in where we can get videos like these - offering clear explanations of the actual theory. Very well made in my view.

[@TayyarePilotuOfficial]

Best video ever made about Bell's theory and the meaning of Epr-Kopenhag combat.

[@ThePoptartjunkie]

This is by far the best explanation of quantum entanglement

[@danjdavison]

How can a particle have a Q+ spin and a - spin for X and Z, when X and Z are components of the vector Q?

[@LKRaider]

Dan Davison that's my question as well: In theory you could have infinite variables if you take all the possible angles between Z and X, would that mean you would have to account hidden variables for all of them? Doesn't seem to make sense!

[@willemvriezen9652]

Indeed I also have a problem with, is the fact that all cases Z, X and Q have the same probability and are totally independent. I would assume that when Z and X are positive, Q is positive as well and can not be negative.

[@TheTck90]

You have to remember that those vectors he draw for the spins are not in real space, but in complex vector space. So the 45 and 90 degree angles don’t behave the same way as for real vectors.

[@spindoctor6385]

@@TheTck90 Isn't that the point that the 2 previous guys are making? (LKRaider and Willem Vriezen) If that is the case (i dont know if it is or is not, i am just trying to clarify) then would a measurement at 89 degrees also be independent of the measurement at 90 degrees?

[@Alkis05]

Here is what happens: regardless of what Alice measures, if Bob measures in the direction Q+, the result can only be Q+ or Q-. There is no intermediary state possible. It has to be aligned to the direction of measurement. But, depending on the measurement that Alice makes, it affects the probability of Bob registering one Q+ or Q-. Since Alice measured Z+, Bobs electron would want to be Z-. But since it can only be Q+/- and since Q+ is further apart from Z- than Q-, it has a much lower probability (only 15%) of happening, because it would have to "change" it's momentum a lot more than for Q-.

[@handsfree1000]

This paradox has been giving me a lot of sleepless nights lately so thanks for this

[@MrDino1953]

This video has left me in a superposition of both understanding and not understanding.

[@obscuredoblivion444]

I love how he says , "Right now!"

[@ottomol5647]

CONGRATULATIONS FOR THIS OUTSTANDING EXPLANATION OF BELL`S INEQUALITY....FROM BRAZIL.

[@ang5898]

hi arvin, I just wanted to say that I really really appreciate your videos. they make me so happy and teach me a lot, keep up the great work ❤

[@craigkdillon]

Oh Oh, consider this an intervention. There is danger in collecting fascinating interesting but ultimately useless information If you collect a finite, but irrational, number of fascinating interesting but useless information ----- you will turn into a NERD. Be warned. This condition, once attained, is irreversible. You will spend your life boring people at parties, having people turn away from you because they can't quite get what you are on about. It is very sad. So, next time you come to this channel be aware of the risk. I forewarn you, so you don't spend your life like mine -- I, too, am a NERD.

[@vedantsridhar8378]

@@whirledpeas3477 but also false

[@stephenbrickwood1602]

@@craigkdillon Hahaha Hahaha Hahaha 😆

[@craigkdillon]

@@vedantsridhar8378 You say that I am not a NERD?? So, you are defending me? Or not?? I am confused.

[@vedantsridhar8378]

@@craigkdillon Sorry, I thought nerd was an insult.

[@kriss0214]

A truly exceptional explanation of the maths behind Bell’s inequality without it being unnecessarily confusing and complicated well done 👍

[@tarzanautowala6506]

Einstein is right : When I was asleep at home during physics test at school , I got a call from my school , the school existed . It was worth skipping the test . According to neils Bohr My school shouldn’t have existed cuz I was asleep ( not conscious) .

[@francoisdesnoyers3042]

The school "shouldn't" have existed... inserts a moral dimension into the equation of existence. It appears to be saying : Don't do anything behind my back. And that is paradoxical in that all science tries to do is to figure out what has been done behind our backs. So, in antiquity, electrons, protons and the like simply did not exist? Or they shouldn't have? Ah, when science dips its toes into philosophy...

[@robertl.fallin7062]

I think therefore the school am?

[@bonedog5130]

This confirms my theory that when i close or cover my eyes i become invisible

[@federicoalonso9066]

@@bonedog5130 How so? I will like your comment on what you said.

[@jaredf6205]

Are you guys all stuck on the "observer" thing? If so, you've really misunderstood what's going on.

[@ankish0394]

Finally, this has been revealed in 2022, by giving the Nobel prize in physics for Quantum Teleportation.

[@PhysicsHack]

I've never seen a good explaination of this. This was clear, thank you.

[@MrBollocks10]

Me too BBC , YT etc. I thought I had half a clue until I watched this.

[@MikeTrainormusic]

I've been binge watching these video's like it's nobody's business. Really enjoying the presentation and content, a lot. Good stuff

[@ArvinAsh]

Nice! Welcome to the channel my friend!

[@omsingharjit]

6:00 this is what happens when two Great scientists Argue both win , and rule changed. because QP says , superposition and entanglement should exist ! Which exists. CPhy says , Nothing can't travel faster than C. It's also True . So.. quantum physics and Classical physics Are in superposition both working at same time in same universe.

[@sheikmohamedamanulaa3898]

So if qp and cp work in superposition in the same universe then it implies that at the very end qp wins

[@omsingharjit]

@@sheikmohamedamanulaa3898 if you talking about singularity then yes

[@hexagerardo]

*In fact, there are hidden variables, you just have to accept that some of their combinations have negative probability:* P(+Z,+X,+Q) = 0.3018 P(+Z,+X,-Q) = -0.05177 "negative probability" P(+Z,-X,+Q) = 0.125 P(+Z,-X,-Q) = 0.125 P(-Z,+X,+Q) = 0.125 P(-Z,+X,-Q) = 0.125 P(-Z,-X,+Q) = -0.05177 "negative probability" P(-Z,-X,-Q) = 0.3018

[@marcobelli6856]

What even a negative probability is supposed to be?

[@hisholiness4537]

"Truth is, the game was rigged from the start."

[@zemm9003]

This is probably the best video I have ever seen on this channel.

[@luminous420]

My new favorite Science Channel.

[@ramyafennell4615]

2022 Nobel Prize awarded for showing QM and non locality is proven as in Bells Theorem So I came here after searching many explanations. This terrific Arvin...thank you so much...really really got it now.

[@schmetterling4477]

Quantum mechanics is perfectly local, it's just not separable. That's not the problem. The problem are people who don't understand the difference between the two terms. ;-)

[@spudhead169]

There's something wrong with the inequality assertion. Assuming hidden variables, it asserts that Bob measuring positive Q is 50/50 when Alice measures positive Z right? I'm sure that assertion is incorrect to begin with. Let's expand this a little and give each particle a normalized angular momentum vector [X,Z], they're hidden variables after all so let's give them real values. Now, someone tell me how to calculate Q from that vector. It's not just midway between X and Z is it? No.

[@dropdatabase8224]

I was about to type a knee-jerk rebuttal to this when I thought about it. It's not quite as simple as a regular normal vector but essentially you're right. To get a 50% split, the 45 degree rotation Q would have to be taken from a linear ramp from X to Z, but this change is not linear, if it were it would violate the normalization. it's sinusoidal. That's easy to visualize, an X and Z value of both 1/root2 gives a Q of 1.0 NOT a Q of 1/root2 as would be the case for a linear change. In fact exactly the same rate of change is required as is used by QM, sin2(pi/8). This can't be right, someone would have spotted the error by now surely. It would mean that hidden variables actually has exactly the same result probability as QM.

[@gamecoolguy619]

Every physicist does this even Einstein did this where he use the speed of causality to disprove the theory. Even though they are x away from each other where x > c they were orginaly together hence they could be linked and just as the expansion of space does not break causality this does not either as the information is the whole wave function (or whatever you want to call it). However if it was the case where there is no entanglement and it is an illusion than it would be that at the start the particles were given the state f(x) and -f(x). This way no matter when you measure (or when you don't they will always be opposite). What f(x) is not known as it currently stands but the proof in the video with it being a straight line was just placed out there using probability of the previous example which has no relation to this. In a deterministic model there will never be a probability just formulas to calculate values based on the inputs, so this was obviously not a valid proof to disprove determinism...

[@sigintsys123]

You are correct. The classical and quantum outcomes are the same. I see this time and again with QM. The mystery of it can be attributed to poor understanding of classical physics. I've also run a classical double slit experiment and I get an interference pattern.

[@markrobinson7465]

Yes. Wave equations determine the probability a photon will be found - the probability density function. The electromagnetic spectrum includes both radio waves and light. The emission and collection of energy from dipole aerials is presumably understood. Can the energy quanta of photons be just the energy levels of the electrons in the atoms emitting and collecting them? I believe Schrodinger ended up thinking there may only be waves. The inequality seems to come from the assumption there is a particle somewhere.

[@tim40gabby25]

Superb video. Breathtakingly clear exposition. Will watch again, like a favourite story. Old UK duffer here :)

[@rontiveros]

I’ve never had a clearer “you earned my subscribe” moment on KZbin. What a well put together, amazing video.

[@j7m7f]

Hi Arvin, I think there is a little mistake in this video, or I got wrong understanding of sth. In 14:40 you are saying that if B measures in Q direction which is 45 deg to Z direction on which A maesured positive spin, then B in hidden variables would have 50-50 chance to get positive. I think in 45 deg he would have 75% in hidden variables to get positive, what is even shown on chart in 15:10. Anyway, in 15:40 you give the right numbers. Or in 14:40 you meant sth else?

[@LeTtRrZ]

This blew my mind. I was convinced for a very long time that Bell was somehow mistaken or misinterpreting what was going on, but I was wrong. What in the world is going on with these wave functions? Could this somehow tie into the potential to discover CPT violation?

[@neilweber1749]

I believe bell is wrong. I actually think there is a fundamental property that we do not understand that causes these probabilities. Hidden variables is correct but what is actually happening is that certain ways of collapsing are more likely. Most probably in a way that looks completely random to us.

[@LeTtRrZ]

@@neilweber1749 It’s funny that this should pop up now of all times. Wasn’t the Nobel prize recently awarded to people who investigated this?

[@neilweber1749]

@@LeTtRrZ Yes this is why this video is here i imagine. there are some physicists who do not agree with the current accepted interpretation. Which is always good for new ideas. I wish I had more time to study indepth but i do not. I take my reasoning from the double slit experiment. There is something we do not understand fundamentally about the wave function. But in saying that our calculations seem to work as most computers etc need quantum calculations. As do newtons calculations if you get my meaning.

[@Max-zy2ie]

Thanks!

[@ArvinAsh]

Thank you.

[@basedbax7577]

"local hidden variables" sounds like computer coding

[@fahimjunayed5894]

Yeah. You have to first make it public otherwise it is hidden. [Only true programmers can understand]

[@vjp2866]

@@fahimjunayed5894 Its possible in c++

[@theoneed2051]

Private

[@yasir4511]

Dear Arvin, i have seen so many videos on the topic but i must say that you have nailed the explanation at its best and not only in this video but in lots of other videos of yours. Thanks for putting your brilliant efforts to let us understand the topics that we are not much familiar with in our institutes.

[@ArvinAsh]

Glad it was helpful! Thanks for your kind words.

[@anacasar8159]

This is a role model for how to strive towards being a true educator. Thank you for your meaningful work.

[@FrasAmalPushp]

Beautifully explained! Just loved it to the core!

[@beebee_0136]

Found this video after Aspect, Clauser and Zellinger won the 2022 Nobel Prize in Physics demonstrating the potential to control entangled particles in practical uses of quantum computing and telecoms. But I wonder if in the process, the trio's works also involved explaining quantum entanglement phenomena just as you predicted at 17:38. Else, the quest for an explanation continues.

[@GizmoMaltese]

I'm here for the same reason. Yet I still don't understand Bell's inequality. He lost me at Sin^2 blah blah. I guess I need to go back and understand spin in QM.

[@beebee_0136]

@@GizmoMaltese you're not alone, my friend.

[@lililliil1761]

While any kind of hidden variable theory violate the equation, the fact that quantum mechnics doesn't comes admirable😮 I wonder why we can't build deterministic local theory which calculate probability in the way of quantum mechanics😢

[@schmetterling4477]

Relativity.

[@mikeycomics]

you make some of the best videos, i like the way you present info, you're an entertaining person to listen to! thanks for all these and keep up the great work!

[@adibmohareri1223]

This was so inspiring! Thanks Arvin!

[@7grims]

you are my favorite youtuber explaining quantum theories, cause you never use equations nor complicate, you always find ways to explain it to the everyday people out there. But this video wanst one of those :(

[@ArvinAsh]

Thanks. This one required math to prove the inequality. I tried to make it as simple as possible. But Bell's inequality is one of the most difficult subjects to understand. Do have another look. It is less complicated than it might appear. It takes multiple viewings by everyone if you really want to get it.

[@dougaltolan3017]

I STILL don't get it, and it hurts... I think its that I don't understand why x, z, and q are treated separately when a (the angle of spin will do). If the angle of spin is the true hidden variable, surely ALL of this goes away.

[@ante3807]

Arvin is so great. Love this channel

[@vickykothekar3321]

The best explanation....in simple language and very good examples for such a hard topic....u r really awesome ARVIN

[@robertschlesinger1342]

Interesting and worthwhile video on Bell's Inequality.

[@avriselig1957]

Dear Arvin, This is a really good 'simple' representation of the EPR paradox and Bell's inequality violated in QM. A few things remain unclear to me (very most likely due to my lack of thinking/ understanding). But first about my background: I studied physics and was fascinated by QM the first time I learned about QM. I asked my professor at that time some more background info and he gave me the EPR paradox as an exercise. I concluded that the spin information travels faster than light, which I knew was in violation with special relativity. That was back in 1976. I left it for what it was, finished my studies, did a PhD in nuclear physics and almost the rest of my working career was on (satellite instrumentation for) remote sensing of atmospheric composition for which I was program leader at SRON Netherlands Institute for Space Research for almost 20 years. Now, after my retirement I wanted to pick up where I left in 1976 and found your video on KZbin. My questions and remarks to your excellent video presentation: - 1. The fundamental one in the EPR 'Gedankenexperiment': If you measure spin up (in any direction) for photon-1, then you know - preserving of total angular momentum - instantaneously that photon-2 must have the opposite spin (after all, the total angular momentum was 0). That is valid both in hidden variable theory (where the spin direction of the particles was known from their creation) and in QM (where both particles have all the spin direction simultaneously until you perform a measurement . So what is so special here? - 2. The double slit experiment for the particle-wave duality of the photon: You actually mention the case of a single photon where you end up with one hit on the screen, which is nothing special. I think it would be better to explain it the following way: If a photon resolves to a point on the screen (that only applies to very low intensity sources so that you can indeed speak of single photons) the measurement is when the photon hits the screen. Thus, in QM, intensifying the photon beam the experiment should give different outcomes, i.e. the photons not necessarily always hit the screen at the same place. And indeed they don't. Slowly intensify the beam will result in hits on the screen forming the well known interference pattern of a wave. - 3. Arithmetic in your example of Bell's inequality when comparing hidden variables theory (HVT) (linear) and QM (sinsqr): something is not right there: if angle (Z, Q) = 90 degrees, then you actually have angle (Z, X); and we have seen that in HVT P (Z+, X+) = 1/4 and not 0.5 what am I doing wrong?? In QM, story is correct: sin2(Z, Q)/2) = sin2(90)/2) = 0.5. Looking forward to your explanation! Kind regards, Avri Selig, the Netherlands

[@avriselig1957]

The answer is that Bob can not know in which direction Alice the measurement of the spin has performed. The direction of the measurement is missing in the story!

[@avriselig1957]

That is the answer to question-1

[@schmetterling4477]

Are you looking for a girlfriend? Sorry to say, but this is not a dating app. ;-)

[@dwinsemius]

@Arvin Ash Do you do any presentations using three pieces of polarized film? The demonstration where inserting a film with axis at 45 degrees between from two crossed films at 90 degrees from each other _increases_ the transmission sounds similar to this discussion. It's at least similar to the extent that its theoretical explanation depends on the measurement probabilities of photon spins that are non-linear.

[@winstongludovatz111]

The argument is based solely on the following assumption (A): the spin of the two photons will be measured opposite in all directions. This implies that the event [Z+,X+] is a subset of the union of events [Z+,Q+] and [Q+,X+] from which the inequality follows trivially. All else is irrelevant and confusing and introduces unnecessary assumptions (such as equal probability for all events E1-E8, the factor 8 etc). Whether or not (A) is true needs to be ascertained by experiment.

[@nmarbletoe8210]

but the results depend on if the detectors are in the same orientation or not

[@evollove19]

Could be some fundamental law of physics we dont get, where there is a deeper reality that everything is localized at one point. Like the holographic universe idea or the info on the surface of a black hole. But instead of reality being 2d flat surface, its 1d. Or the entangled pair only look to be far apart, but really the space between them is folded in a way we cant tell and they are really right next to us like some type of worm hole when they fold a piece of paper, in all the science fiction movies to explain worm holes. Was wondering if there was a way to tell when someone on the other side of the universe has measured the entangled pair? Could something be used to detect that he has measured it? but only after the person on the other end has measured it? That way you can have multiple boxes with an entangled pair, that you do not measure, but the person on the other end, measures only certain boxes. then dependent on your end, the ones that he measured signal to you a certain combination, therefore communicating something. ?

[@brookefoxie9610]

I would imagine this has already been proposed. Perhaps go do some research and let us know what you find?

[@evollove19]

@@brookefoxie9610 Ive tried in the past, in the idea of knowing when the other person on the other side checks it. I Am not good at researching and understanding. Arvin Ash is a great explainer. Thats why I asked him to confirm. From what I understood, there is no way to tell if the person on the other side of the universe checked the spin and taking the particles out of super position. Its like you cant detect what happening in the box without taking it out of super position. But I am also asking the question to see if someone with more expertise can think of something using this concept.

[@supreethbhaskar3405]

@15:02, I see a problem there. The probability that bob measures plus in Q direction given that Alice measures plus in the z direction is given by sin²(45/2), that is: P(Q+|Z+) = sin²(45/2). Since the probability that Bob measures plus in the z direction is 1/2, it follows that P(Z+,Q+) = P(Z+) × P(Q+|Z+) = 1/2 × sin²(45/2). For the hidden variable theory, we wrote it correctly. That is: P(Z+,Q+) = 1/4. That is P(Z+,Q+)= P(Z+)×P(Q+|Z+) = 1/2 × 1/2 = 1/4.

[@jcinaz]

After viewing for the second time, I understand the process and the math and I agree with Arvin on his conclusion. Never thought I would say that. Wave function rules. Particles are not particles until the wave function collapses. A photon has the potential of being a particle, but its essence is a wave.

[@ArvinAsh]

Perfect!

[@Arboldenrocks]

not quite. the photon is always a particle, the wave says where it can be. the field is everywhere... but it can only be absorbed by 1 charge. so is it really everywhere? it may be that the particles are only emitted when they are also absorbed and don't go in other directions. that part is non falsifiable, but we always observe inverse square fields. arvin hash is 20 years behind western science as usual

[@AhsimNreiziev]

+[John Carter] This is sad news. Even more sad is that I am months too late to do anything about it. Because I am afraid that Arvin's conclusion is utterly wrong. Or.... at the very least utterly unfounded. He shouldn't feel _too_ bad, though, as Bell's Inequalities form what is pretty much the most misunderstood and misappropriated thing in all of Physics. You see, the so-called EPR Paradox consists of 2 parts. The central crux of the argument, and the "paradox". Contrary to popular belief _[and by "popular belief", I mean the beliefs of the adherents of Orthodox Quantum Mechanics, which is the modern form of the Copenhagen Interpretation]_ , the central crux was in no way disproven by Bell, nor by the experiments that prove his Inequalities were violated by Quantum Mechanics. The central crux of the EPR argument, of course, was that considering Entangled particles exist, the preservation of Locality *requires* Hidden Variables. There is *NOTHING* in Bell's Inequalities that disproves it. Nor could it disprove it, because that argument is pure logic, with no assumptions or any other form of wiggle room to get out of it. Now, what John Bell did prove was that there was no paradox. He did this by proving that even *_with_* Hidden Variables, Locality would *_still_* be violated. But neither result can make any sense without the other. Because Hidden Variables either exist, or they do not exist, EPR + Bell *TOGETHER* prove that Locality *must* be violated by Entangled Quantum particles. It also says precisely *nothing* about whether or not Hidden Variables exist. As a side note, Pilot Wave Theory, aka Bohmian Mechanics, which of all Interpretations of Quantum Mechanics makes the non-Locality the most explicit, was the favoured Interpretation of Bell himself for precisely that reason.

[@-danR]

@@AhsimNreiziev I appreciate that at least _one_ commenter has refused to join the avalanche of praise that monotonously recapitulates every other youtube physics video commenting proclaiming the sheer pellucid genius, accuracy, and pedagogical simplicity of the creator's production. That said, I see no reason to complete your thought with yet another sideline hollered call for Pilot Wave speculation which, like String Theory, seems to have forked into dozen sub-theories; because if a theory is sound, hey, why not have themes and variations. There should be one ready at hand fitted to plug any leak.

[@RWin-fp5jn]

Arvin, you are by far the best science communicator on the web out there. That said, Einstein was not entirely incorrect with respect to quantum entanglement. What he simply failed to see (as did his peers after him), is that there is perfect symmetry in physics between Energy and (inversed) Space, NOT Mass. In spacetime it is Space that forms the grid. Yet at the subatomic scale (sub Planck rather) it is Energy that forms the grid (we already express electron orbit distances in eV's). By sheer logic also Mass and Time then need to swap in their continuum function of Clock and Inertia. Both setups are however valid! As such 'quantum' entanglement is simply 'energetic locality' meaning we have two particles with the same energy (spin) values in three directions and which are present at the same 'mass' moment. They can thus influence each other instantly, regardless of the amount of spatial distance between them. This is precisely symmetric to 'spatial locality': Here we have two particles with the same SPATIAL values in all three directions at the same 'time moment' allowing them to influence each other regardless of 'Energetic' distance. See the perfect symmetry? Now the entire misconception that has been going on for 100 years is that we we interpret E=MC2 wrongly. Yes it is a mathematically correct equation, but it does not mean E and M are fundamentally 'equivalent' any more than Space and Time are equivalent in the formula of Distance (space) =Time*Speed. So what does E=MC2 stand for? Well if you swap Energy with Space and Time with Mass in the spacetime movement formula above, it becomes: E=M*E/M or E=M*[Nm/kg=m2/s2=C2] . So E=MC2 is actually the movement formula at the sub atomic (sub Planck) Scale. We know this to be true, because of two observations: 1. When looking at nuclear fusion, the separating distance of two hydrogen core right before merging becomes so small (smaller than the Planck scale) that indeed we must see the movement equation on the sub atomic scale start to dominate. And we know E=MC2 emerges. 2. Quantum leaps in atoms. Here we KNOW it does not take TIME to move one electron form one SPATIAL location to the other. Rather it takes MASS (relativistic mass of an incoming photon) to (time instantly!) move the 'electron' from one ENERGY location to another. 3. We can now also explain 'particle wave' duality. It is not true that particles at the subatomic scale are everywhere at the same time. What we see is the ENERGY of a particle spread out in the subatomic world. Why? because ENERGY forms the spiraled grid a the subatomic scale! So Energy is a PARTICLE property in our ST continuum , but it is the GRID inside the sub atomic continuum. Thats all there is to it. Again, QM is a good mathematical approximation, but fundamentally we are looking at a dual (orthogonal) setting of our continuum... Maybe stuff for an additional video?

[@SquirrelDarling1]

So say if I invite the universe to a casino with me, would that be considered cheating or would there be no consequences if I keep it on the down low?

[@promerops]

I have long suspected that the Universe doesn't play fair.

[@usmanshahid8277]

Out of all the physics videos online yours are def. The best

[@AbulkalamAzad-qz1vv]

what a beautiful explanation for us lay persons.

[@tunadida4323]

Beautiful ideas simply and elegantly explained.

[@luis5d6b]

OK this is by far the best explanation of this phenomenon I've ever seen, great job my friend

[@ian731]

How deduced 15:03 , From where he got proportionality with sin(θ/2)

[@MadMax-xc4lr]

Its the graph sine function..

[@truthnow5245]

How do they know that the particles are measuring came from the other particle

[@vilitoivonen122]

This has always been my biggest question, and how can they take the particles so far apart for measurements without interfering with their properties in any known or unknown way

[@creatorsremose]

This video had taught me a very valuable lesson... people have very different understanding of the word "simply".

[@ArvinAsh]

Sorry, this was probably the most difficult video I ever made. It is one of the most difficult concepts in quantum mechanics. Hopefully, you will find my other videos more comprehensible.

[@creatorsremose]

@@ArvinAsh Your videos are amazing and I love your attitude. I agree that this is a particularly spicy topic to try to explain "simply" and you did great. I love physics conceptually it's just that math (and probabilities) are confusing to me. I went through at least a dozen videos to finally get a rough idea of what quantum fields are perceived to be while trying to ignore the math that explains it. I just needed the concept.

[@sebastianjana5423]

@@ArvinAsh. No.

[@yanceyschwartz]

It is a very hard concept to get or explain. So a "simple" version of it is always going to be relative to how hard the original concept is.

[@rhopsi-q6b]

This was REALLY(!) well explained.

[@dilipdas5777]

Your channel is one of the best youTube channels

[@evanpenny348]

6:43 Left handed "PAIR" and right handed "PAIR"?

[@DuchAmagi]

16:58 How could we measure a particle in one place and have the wave collapse across the length of the whole universe instantaneously and not say that the information has spread faster than the speed of light?

[@alaididnalid7660]

Not sure, but the faillure of using it for means of communication leads him to conclude that currently it cannot yet be stated that it travels faster than light. The randomness of the collapse is a reason to state that it is not faster than light.

[@omari4625]

Dam wish I saw this video back in modern physics.Would’ve made my lab reports legendary.

[@matt-g-recovers]

That Magellan looks perfect for my current obsession. Thanks dude!

[@augustinemmuogbana3382]

I have been struggling to understand this for many years from Prof. Leonard Suskinds lectures but I couldn't. But today, this video has demystified it for me. Thanks a bunch.

[@ayeyebrazof6559]

Thanks very much for the explanation, I need a clarification though: at 11:00 you says that there are 8 possible outcomes for the measuring, how can we be sure that these outcomes have the same probabilities i.e. 1/8? Or do we have to believe you that it is the case for a "hidden variable" théory? Same at 15:00 for the other sinus law probability in the case of the "quantum universe".

[@hasanshirazi9535]

Congratulations! You have explained a very delicate concept in a simple and easy to understand manner. What do you think about Pilot Wave theory? Does it offer any hope of resolving non-locality paradox of QM?

[@ArvinAsh]

I see it only as a consolation to those insisting on a deterministic description. In my opinion, it is a messy mixture of quantum and classical concepts. But I will be covering it in a future video.

[@johnjacobs6062]

best clear explanation of Bell's Inequality I have read or seen, thank you

[@Flacopro40]

Could it be possible that particles are 4th dimensional and quantum entanglement is the connection between two different 3d parts of a 4d particle?

[@ArvinAsh]

It is possible, but there is no evidence for this 4th spatial dimension.

[@P.L.D.]

@@ArvinAsh They are part of the same wave, that is why they are entangled

[@richardaitkenhead]

Space and time is the 4th dimension

[@Euronius]

@@richardaitkenhead Space IS the three dimensions that we know of.

[@draganpetrovic1991]

I really like how Arvin Ash explains some obscure concepts in quantum physics. I remember that it always sounded stupid to me that the observer could influence the experiment. I considered it to be any interaction with the experiment that affects it. I found the confirmation in an older video of Arvin Ash! Now I really liked the explanation for entangled particles, that they are part of the same probability wave. I didn't come up with that myself, but it sounds logical, as much as it is possible in quantum physics. It can't be more than that, because we're still investigating the laws, not the reasons (if that's ever possible). Hello Arvin, keep it up!

[@TinHatRanch]

Just imagine if the scientist who has the probability of solving quantum mechanics is alive right now but doesn’t get into the school necessary because “diversity, equity, and inclusion” bar him or her from acceptance. #science.

[@hichaelhyers]

Shut up.

[@legendarynoob6732]

There's a lot wrong with that statement. By saying "diversity" you mean poc and by "scientist" you mean a white dude right?Then what you're saying is poc are not as intelligent as whites and that those poor dudes lost their chance because some dumbass poc got it coz of diversity. Now what about the whites that do get in to University?Aren't they better than the whites who don't?Or are you saying that oppressed people getting education is not desirable?Blame everything on diversity coz "pocs are not as intelligent as muh whites" so "why should they get education"?

[@MadMax-xc4lr]

A genius will find its own way

[@TinHatRanch]

@@MadMax-xc4lr then why is there such an “under representation” of minorities in this field?

[@MadMax-xc4lr]

@@TinHatRanch cause there are less geniuses

[@lahockeyboy]

Thanks for the Magellan tv recommendation, Professor. I just signed up...and thanx for another great video!

[@morsecodereviews1553]

I prefer these longer videos, even though the maths make my eyes glaze over.

[@reyramirez5695]

Actually, the violation of Bell's inequality argues against local hidden variable theories, not non-local hidden variable theories. And Bell came up with this while studying Bohm's theory, a non-local hidden variable theory. Bell rediscovered why Von Neumann's "proof " against hidden variables was wrong, something that had immediately been proven by Grete Hermann and ignored. And Bell's theorem actually argues against all local theories. And it doesn't depend of quantum theory. Reality is nonlocal. And it's been verified experimentally. Kind of crazy, but at least it makes sense, and it is nicely brings wholeness. Bell thought highly of Bohm's theory but also considered GRW-like theories. Anyways, like you said the wavefunction of an entangled system is supposed to be in a higher dimensional space...

[@ArvinAsh]

Good comment! Thank you.

[@runtrls]

The die that Arvin has rolling near the beginning of the video is not representative of a real die - it's got the 5 and the 2 adjacent to each other, when the real die has them on opposite sides (all opposing sides add to 7). Regardless, it's an excellent video, as they always are on this channel.

[@MadMax-xc4lr]

Yes .. But do god play dice?

[@rmchannelsss]

One of your best videos Arvin. Thanks

[@manog8713]

Well done Arvin. Best explanation of Bell's inequality I've seen. Thank you.

[@christiansilvestro481]

The explanation is very simple and you explained it at the beginning fo the video. Angular momentum must be conserved. Therefore if we observe a photon with spin up, the other one must be spin down. There is nothing mysterious going on, other than you misunderstanding basic logic and reasoning.

[@wesjohnson6833]

Another one who cannot accept the non-boolean logic of qm (or even what logic is for that matter). And yet, there it is....

[@EMPATICO4]

17:13 "...and since the colapse is random, it can't be use to communicate in this way" Why?. Great chanel thanks!

[@ArvinAsh]

Great question! I did not get into this in detail, but here is the simple explanation. Since the result that Alice gets from measuring particle 1 is completely random, and the result that Bob gets, from his perspective, is also completely random. And since the two can not communicate each others' results to each other faster than light, no communication of information can happen faster than light. Also, the randomness of the results precludes one from somehow manipulating the result to communicate instantaneously to the other.

[@pralinesouffle]

if you could control the direction of the collapse, you could send a message. but since this is impossible and the direction is random, the outcome at the other end is also random, so no information is transmitted.

[@gonzalogarcia6517]

@@ArvinAsh The paradox of information is supersymmetric. In the same way as from inside a black hole, you cannot calculate or interpret if it has a spin, that is, if it turns on something ... When we analyze a photon-higgs-graviton we can only calculate and interpret that they have mass and charge "0", but if they spin. It is the same paradox of information, since they are the same on different fractal scales. The paradox from inside to outside is supersymmetric to that from outside to inside.

[@noxnc]

In order to communicate you must send organized (i.e. non-random) signals; since the collapse is random (i.e. not organized) it can’t be used to transmit any information. Just think if you tried to send a text message your friend telling her where to meet you. You decide to write the message by rolling 5 dice over and over, adding up the total value shown on the dice each time, and using the result of each roll to decide what letter to type next. How would you ever be able to get the information to your friend? *In case it isn’t clear, the letters of alphabet would be assigned a number 1-26, the numbers 27-30 could represent symbols like commas etc.

[@yomiyama]

You guys look like you forgot that the fact that represents the action of the wave function collapsing in itself holds information, and it says that "Alice is trying to say something" so Bob would still know that Alice tried to say something, THAT still represents information.

[@sstrick500]

I think we've entered the era of, "We know just enough to be dangerous". 500 years from now they'll snicker at our ideas; the same way we sort of snicker at the prior era's "The sun revolves around the Earth".

[@ccmcgaugh]

This is by far the best, i.e. clearest, explanation I've found so far. Great use of graphics. 👍😃👍 Very timely for me as I'm reading The Age of Entanglement by Louisa Gilder for the 2nd time. Highly recommend the book.

[@jamesruscheinski8602]

What does it mean that the angular momentum are entangled only if measured on the same basis / in same direction? Does this mean that entanglement happen from measurement basis? What else would this say about measurement for entangled particles? Is entanglement from basis of measurement local? Does entanglement at time of measurement mean that entanglement happens before observation?

[@LinuxLuddite]

So in Avengers End Game, Tony Stark was using EPR paradox to reference a wrong phenomenon that led Scott Lang to appear in different stage of his life while trying to time travel. That's funny cuz End game took a dig at all the time travel movies for propagating wrong notion of time travel.

[@ArvinAsh]

Yeah, I think the movie attempted to sound "scientific." This is perhaps better than most sci-fi movies (I'm looking at you Star Wars), that gloss over any semblance of science.

[@sir-gayrusskovich4018]

this is even more simplified and intelligible than Prof. Khalili's game with the demon analogy in his atom series .. great job!

[@giulia7626]

this was a phoenomenal explanation! Hats off to you, subscribed. I've just started taking QM in my astronomy major, seems fascinating to say the least!

[@lanimulrepus]

Excellent presentation... Simple and direct...

[@philochristos]

That was really interesting, and Alice is really cute.

[@jacksmoba603]

And Bob 👀

[@Dannysen]

I once thought people ran into blackhole and measure entangled particles is a way to pass information outside the blackhole because information could pass faster than light, but I finally got verified by this video that it is not possible because the information about the entangled particle is random and not useful at all. Excellent video!

[@valueofnothing2487]

Yes I believe that both so-called particles are governed by the same probability wave function, which is created at the birth of the particles in one place.