Bell's Inequality: The weirdest theorem in the world | Nobel Prize 2022
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- Опубліковано 6 жов 2022
- Last year, in 2022, John Clauser, Alain Aspect, and Anton Zeilinger were awarded the Nobel Prize in physics. Their groundbreaking work was built upon one of the most significant discoveries in the history of physics: Bell's Theorem, which was originally formulated by the late John Stewart Bell. In this video, we delve into the reasons why Bell's Theorem stands as one of the most important and perplexing results in the annals of physics. Join us as we celebrate the achievements of these three remarkable scientists who, through their contributions, laid the foundation for cutting-edge technologies rooted in quantum information.
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Thank you for not playing annoying music whilst we're trying to follow the explanation.👍
Actually underrated comment. People these days have no attention span whatsoever
@@TimEnjoysGnocchis "span" not spawn. But yes, I hate unnecessary background noise.
Some ones Thenthive!!!
They need to spaun their attention
I to am glad that there is no annoying background music.
Understanding it is one thing but then explaining it in a simple way to ordinary people is a craft in itself. Excellent lesson.
No one understands it. All we know is the effects that are measurable, not how it actually works.
It sounds like a scientific charlatanism. Everything measures everything therefore the Universe is deterministic but not necessarily self-knowable.
@@hoochygucci9432 Anyone who recognizes that the Everettian interpretation is self consistent understands how it actually works.
Where did the CSHS thing come from?
What happens to Victor and what do these particles have to do with echother?
In a significantly larger scale, apples, oranges, and peaches look like particles. Victor sends an apple to Bob and a peach to Alice. So what?
Very smart individual.
Bell did not assume "realism". In fact he pointed out himself (!) that his theorem is about models, not about reality. He instead assumed a second property called "measurement independence". This was pointed out among others (ironically) by one of the recipients of the Nobel Prize, John Clauser.
@SabineHossenfelder The algorythm just recommended this video to me after watching your most recent video. You must have collapsed our entanglement and this was inevitibility (let me tell you I don't understand quantum entanglement without telling you).
John Bell was wrong! The EXPLICIT information (information describing the waveform) is utterly deterministic. Free Will arises out of the complexity of the RELATIONAL information (the information regarding the interrelationships between the various wave-forms). BTW, I'm a fan of your channel!
I'm guessing new assumptions were thrown in so people don't make unrealistic conjectures arguing moot points. Love your dry sense of humor you put in your videos.
@@ThePonymaster2160 Id love to read your paper, got a link?
damn @@chilloutnostress2586
As Einstein said, “If you can't explain it simply, you don't understand it well enough.” you have shown that you indeed understand this completely! Thank you for the simple explanation and the example for us to try.
It sounds like a scientific charlatanism. Everything measures everything therefore the Universe is deterministic but not necessarily self-knowable.
Obviously not if she didn't win the Nobel Prize lol
Simple my ass !!! There is nothing simple about Quantum Mechanics !
Yes, I agree that her simple explanation demonstrates that she thoroughly understands this subject. The quote is often attributed to Einstein, but I believe there is no record of him saying it. The source of this quotation is most likely Richard Feynman who once said, "I'll prepare a freshman lecture on it. If I can't explain it to a freshman, I don't understand it."
that saying has served me well in evaluating my own understanding, love it
One thing that is interesting is how much Einstein influenced Quantum Mechanics, even if he did not agree with the philosophy behind it. The EPR paper was the end result of a series of arguments between Einstein and Bohr over the underlying meaning of QM. Einstein would present an argument against the probabilistic nature of QM, and Bohr would provide a counterargument showing Einstein where he was wrong. Eventually Einstein came up with the argument in the EPR paper that Bohr could not answer. Bell also did not answer it, but he came up with a way to, in theory, answer the question about which interpretation was correct. And then the three Nobel winning scientists came up with experimental ways to use Bell's theorem.
Without the EPR paper quantum entanglement would probably never have been looked at and measured. So even when wrong Einstein made a great advance in science.
The operative phrase here is "in theory". What physicists are supposed to answer is "in reality". That is what the subject is all about: "physical" reality, previously "natural philosophy". I doubt theoreticians of quantum mechanics are claiming the theory is complete, so I fail to see how this proves Einstein was wrong. What he was saying sounds axiomatic to the whole field of physics. Give it up if you wish, but that is giving up "physics".
@@jamescaley9942 This year Nobel Price was given to people who proved this "in reality". It was an experiment-based prove that Eistein was wrong.
Think we should get over Einstein - nobody has a problem with Newton but we moved on - great thought leader as time-sensitive lol
@@jamescaley9942 This sounds like something ppl would have said about Newton, if anything modern physics have already proven Einstein wrong so 🤷♂️
@@franknugent2801 That will and should not happen until an accurate theory of quantum-gravity is developed.
John Stewart Bell's birth town of Belfast (and, of lesser significance, my own birth town) has a street interestingly named for the theory rather than its discoverer: 'Bell's Theorem Crescent'. I discovered it accidentally on a walk around Belfast a couple of years ago and have often wondered if it existed on Google Maps prior to my observing it!
No way to know now you've collapsed that sign
That's funny, I saw it as 'Bell's Theorem Loop."
LOL
Was it a random walk?
That's funny next time I'm there I'll look it up - so much work has been done in other places that are not Stanford/MiT .. I found out while in Manchester
It's wonderful what can result from people doing what they are truly passionate about. Paths are drawn so much cleaner and we can conclude collectively, so much more efficiently. Thank you again for another thoughtful and extremely well-presented piece, Olivia ♡
That was wonderfully clear and well presented. Excellent stuff !
I wanted to see the physical experiment
Love how they proved quantum mechanics is real and it just leads to "we have no idea what the hell is going on"
all it proves as far as i can tell is that what (properties) we measure has no definite value split between two particles as per QM theory .. nothing more nothing less
So, this means Heisenberg (Walter White, Breaking Bad) was wrong about time travel being impossible? I'm too old to verify the math behind quantum theory, entropy, etc.
should have figured out by the "Miraculous" experiments...
I love how everyone and their brother is dumping on Einstein, then have to admit quantum mechanics is incomplete, after all. 😃
Outside of entanglement. It is still a HUGE consequential thing to demonstrate with an experiment.
What an excellent presenter; you can feel the respect for the material and the people involved.
@@amoxzi jeez man... you forgot to point out her necklace is a bit crooked.
@@stark-hampton3118 Okay thanks.. Now that is all I can focus on :(
@@brakgeluid should've read the critiques after enjoying it lol.
I can't agree to that. She might become a good salesman, but not a teacher or scientific presenter. From 4:20 to 8:30 she was laying down the content of thought experiment, but instead of showing how it leads to controversy, she just finished it with "now suppose that instead we use entangled particles, and you see, we actually going to measure a different result". In this presentation it looks like she insisted that "the math broke down", not some physics phenomenon, as "
Always thought a presenter was someone who got presents ready for people, like a third party service, kind of like an elf, but then I realised that they rarely came with gifts, mainly because they were a 3rd party I guess and I never saw them like that elusive fat jerk who eats all the cookies and leaves the neighbour's stolen badmington set as a "gift", and probably stole something while he was at it for the next kid and cookies. Then I realised that presents are only called that because they are presented to somebody, which preferebly would be myself (reciever, not giver (me receiving the the present and not the one labled a "presenter", nor a 3rd party in the mix who is preparing the present (or presentation))). Then I realised potentially that I would be receiving less presents, and figured that if I became a presenter myself, pehaps I could hijack the system of flow, thereby recieving my deserved and duly proportional amount. Then I realised that If you prepare a present that you intend to appropriate for yourself, it ceases to exist in the realm of "presents", as it is presented to none, except maybe from your left hand to your right. I toyed with the idea of concocting some big fake fanfare "presentation", where I first dressed as a "presenter", then call myself up to the stage to recieve a "suprise", duck behind the curtain, change clothes, then apear with a shocked and thankful expression as I walked to the podium to receive the present, but obviously with noboy there to present it, it fails the test on all levels. I had to concede that at least a 2nd party must be involved to be the "presenter". I think I finally found such a person.
Olivia, it is a joy to watch your presentations. I saw one from Al Khalili explaining Bells inequality, but yours has made it much clearer, which has increased my understanding of Quantum Physics to about 2%. :) Keep posting!
Stick with it! Keep coming back to Quantum Physics long enough, and it's inevitable you will tunnel through.
The only way I see to tunnel through to 28 is 10008 divided by 10007999717. Who knows?🤷♀️weirder than you think.
One of the coolest explanations of bell inequality I've seen and you literally fulfilled fenyman's idea of being able to explain the idea in the coolest possible way.
It's worth pointing out *why* you can't build an ansible (FTL communicator) with entangled particles. When Alice interacts with her q-bit, the probability function does indeed collapse for *both* q-bits at the same time -- but Bob doesn't know that the probability function for his particle has collapsed. Further, when Bob *does* interact with his q-bit, he can't distinguish between the case "probability function has already collapsed due to Alice" and "Probability function just collapsed due to Bob's interaction". Finally, neither Alice nor Bob can influence *how* the probability function collapses to favor one value or the other.
Thus, once Bob interacts with his q-bit he can say with certainty what value Alice will get when she interacts with *her* q-bit but not whether or not she has or hasn't. Since the measured value is random, no useful information has been transferred.
Interestingly, entangled q-bits *do* have some use in communication -- they can be used to authenticate messages. In this scenario, Alice interacts with her q-bit and uses that value as part of the encryption key of a message. When Bob receives the message, he interacts with *his* q-bit to create the decryption key. While a single q-bit doesn't give Bob much confidence that Alice sent the message, if 256 q-bits are used...
While this is an interesting comment, it still doesn't prove or disprove faster than light travel or transfer of energy or information. It just doesn't.
I love how you used the words "at the same time". Delayed-choice experiments have shown that the wave-function collapse even transcends time. Which kinda makes sense if you accept the nonlocal collapse that seemingly violates c. But it goes against our intuition based on our ability to experience the universe.
This is a great explanation, thank you.
One thing that I don't understand is: If Alice and Bob cannot tell whether their probability function has collapsed or not, how do we even know there is any probability function after the particles are entangled? To me, it seems like the act of entangling a particle simply synchronizes the states of the two particles so that they will have opposite values and the probability function itself is only a thought experiment to help explain behavior caused by the observer effect. Is Bell's Inequality theorizing that this cannot be the case because of that 2.8 value?
@@Kevin-ht1ox Yes, that's correct. Bell's Theory is one of the rare cases where you *can* prove a universal negative statement-- that is, there is no function can be constructed, even with perfect information, that can say with certainty what the the state of an undeterminate particle is.
The MinutePhysics video does a much better job at illustrating this (ua-cam.com/video/zcqZHYo7ONs/v-deo.html), with a bonus that it includes an experiment that you can conduct yourself if you are willing to sacrifice a pair of cheap polarizing sunglasses.
@@KastorFlux "...but also any other adjacent particles through localized communication..." If this were correct, then yes, entangled particles could be used for FTL communication.
However, it isn't -- if there are any adjacent particles to interact with the probability waveform would have *already* collapsed. The only valid answers to the question "Has the quantum wave function of my particle collapsed" is "Yes" or "I don't know" -- unless, of course, you have a separate channel of communication with Alice.
If you *do* have such a mechanism, then not only are you in line for a Nobel Prize, you would also make lots and lots of physicists very happy. As Einstein pointed out, lots of physicists are very, very disturbed by the consequences of Bell's Theory and quantum mechanics in general, and detecting a collapsed quantum wave form without collapsing the wave form would go a long way towards proving that quantum mechanics is only an approximation of the *actual* laws of physics.
And you would likely be rich to boot -- stock traders are spending millions of dollars to reduce latency on trades from 10s of milliseconds to 8 milliseconds. 8f you could reduce we it to picoseconds over any distance... There is a market for an ansible even today.
I see lots of comments about this being a clear explanation. What am I missing then? I feel like there's a considerable amount of information missing about the experiment that is crucial to understand anything about it.
A and B are sent a particle and measure x or y projection. x and y projection of what? Some vector? No idea, but I can accept that they measure some kind of quantity that, after normalization, can only be -1 or 1. Then, after many runs of that, they average out their measurements and compute (Ax + Ay)Bx + (Ax-Ay)By. I understand that the outcome of that can not be >2. But, what does that have to do with locality or realism? I don't see a connection there at all?
Then you quickly move to an example with Qbits and the fact that the outcome becomes ~2.8. The conclusion is that either particle moves faster than the speed of light, or realism is incorrect. Again, Why?? What does the speed of the particles have to do with measuring -1 or 1? What does realism have to do with measuring -1 or 1? If the outcome is higher than 2, namely ~2.8, that can only happen when some measurements have not been 1 or -1, but >1 or < -1?
So yeah, this feels like one of those times an explanation is simplified and information is omitted up to a point where the whole explanation makes no sense at all anymore and is basically useless. Sorry for the harsh words, but this is frustrating, haha
Yes, I don't understand why people are saying it's well explained. There're many jumps and conclusions that don't make sense unless explained!
My college physics teacher said that if we compressed the earth somehow so that every molecule was touching, it would then fit into a space the size of the classroom. And my smart friend said, "Yes, but that thing that fits into the classroom is itself made of a substrate that can be broken down into its components and again it is 99.9999999% nothing, and if you break that down, it would be true again." Because at each level there is information imposed on "stuff" and that stuff is again information imposed on different stuff, and that.
So I think we still have a long ways to go to get a handle on things and I am with you and don't understand it either. Nor do I think I ever could.
It is my own guess that if we can go through enough substrates we will eventually observe it as nothingness. But that statement means nothing (g)
It means you are a clear-thinking individual and haven't been brainwashed. Everything from Einstein forward was made up nonsense.
@@marwanadel__
I agree with you. She exactly glides across the surface, precisely without explaining anything that wasn't already clear. On top of that, she does an ugly job of mangling Aspect's name. Careless. Unnecessary. Unprofessional.
Anonymous "Inaugurated," on the other hand, is quite right not to sign their post: all they're complaining about is their own laziness or ignorance. Fake "Inaugurated" is correct only on the point that she cheats about that 2.8; all the other whines are be solved if Inaugurated simply pays a little attention.
Totally agree. She said absolutely nothing. I mean, suppose that instead of Alice and Bob taking measurements, how about we just let Victor keep a record of the properties of each particle he sends? Obviously, Victors table of data would be the same as any data collected by Bob and Alice, Right? The two tables constructed by Bob and Alice combined would would be equivalent to the table constructed by Victor as long as everyone accurately recorded their entries, wouldn't they?
It seems to me that there can be only two possibilities for the '2.8' anomaly. Either, Victor, (Quantum Mechanics), is unconsciously biased and _prefers_ or _favours_ one property over another *_or,_* it is the case that the properties of the particles can change as they travel between Victor and Alice or Victor and Bob which would suggest that the Universe prefers one property over the other. Perhaps it is easier for 'left-handed' to become 'right-handed' than the other way around. Or maybe '+1' spin converts more easily to '-1' spin than the other way around. It may be the case that in a Universe made of anti-matter, Bell's Inequality would be measured as '-2.8'?
I don't know but I do know that if it doesn't make sense then there is probably some problem with an assumption that has been made.
This is somewhat past my mathematical understanding but I really appreciate your taking the time to break it down so I can understand it and hence expand/bend my mind a little. At 61yo I do regret not pushing myself more in my mathematics study- just a word to the young scientists and mathematicians out there: keep grinding!!
Not sure how true it is but I have heard that Einstein expressed regrets for not investing more in mathematics on his deathbed.
Ditto for me. Have gone back to studying high school and first year universities maths in my retirement and now regret that I didn’t do more in my youth!
Wise words. Trying to impress importance of good maths skills on my kids
U r just 61yrs old u can easily become a Mathematician if u want to
Thanks for this. I needed to hear it.
Thank you for explaining it so well! Definitely leaves us with some interesting things to explore regarding the relationship between entangled particles.
A slowly paced video that explains things with the goal of actually understanding them. Finally! Subscribed!
Finally, a channel that isn’t scared to show some of the maths that is so crucial to the underlying physics of this exciting news.
Robin,
I don't think you're paying attention. That's exactly what she *didn't* do. And her mispronunciation, "Elaine" Aspect, is fingernails on the blackboard horrible.
When it came to the math she said "Go look in the caption, The actual stuff is in a paper there..."
She teased us over why the value turns out to be 2.8 and then didn't tell. That's posing, not math.
Lol. Calm down. It's going to be okay. The video is meant to encourage people to look more into the topic.
Great presenting skills, well done! It was even a pleasure just to listen to your presentation and explanation 😆
I went from not understanding this to sort of understanding it. Thank you for the logical and articulate presentation which helped me make this leap.
Fantastic distillation of "spooky action at a distance!" I wish the prof who taught my graduate quantum class had been as effective at describing Bell's inequality as you are.
Excellent work--your depth of knowledge and enthusiasm shine through. Clear and easy to understand with minimal previous knowledge
Yes I loved the fact that there was no annoying background music and Yes I agree with all others that you are an excellent presenter. If I may mention that the Nobel Prize work was not all done in a lab. I watched and loved the presentation on Nova, Eisnstein's Quantum Riddle where an experiment in the Canary Islands Observatory have done some amazing experiments.
Outstanding pragmatic explanation! This opens up a whole new perspective for me! Thank you for your remarkable review!!!
John Bell was a technician in Queens for some years. People realised his genius and helped him get his degree encouraged him to get his PhD. He had died before I started there but by all accounts he was a lovely bloke.
um that is ridiculous and wrong. he was irish, and received all of his education in the UK. he was never any form of technician prior to his phd.
@@mabmab100I can't speak to the technician part, but FYI Queens is a university in Northern Ireland, UK
You meant he was broke...like tesla. This happens to most genius. Sad
@@BobbyT-yj1cw That's not quite correct, or at least potentially misleading. It is too often overlooked Bell was proponent of Bohmian mechanics, an alternative to Quantum Mechanics, that predicts the same experimental results, but where particles have position with out measurement.
Fantastic explanation! Thank you for doing this video.
Thank you Jesus for not only no background music, but also for no camera movement. Thank you for letting Lanes present and for not goobering up her presentation with unnecessary production clichés.
Terrific video. A very easy, digestible demonstration of quantum weirdness. Thank you, Olivia.
How can we confirm with a measurement if two particles are entangled before we run experiments with them, or do we just say they are entangled because we believe some process they go through gets them in a state of entanglement?
It all sounds like a scientific charlatanism.
In reality, Everything measures everything therefore the Universe is deterministic but not necessarily self-knowable.
I love this channel so much. There are always super interesting things going on in the Quantum Computing field and the explanations are actually approachable. I appreciate all of these posts.
Thank you!
and she is looking good! very important for us!
@@ikillwithyourtruthholdagai2000 hhaah true
@@ikillwithyourtruthholdagai2000 sigh 🙄
Maybe someday the way a person looks won’t have anything to do with whether their intelligence is acknowledged.
Thanks for this - I did think of Bell when the Nobel prize awards were announced. I often think of him because I live a few hundred metres from where he was born, in Belfast - and cycle past his house most days.
...but of course, you can't communicate with him.
Maybe he can, he just can't tell at what points his self belief as a medium, meets his probability of self delusion, making the convergent outcome evident, but not quantifiable in a meaningful way.
This is such a well done explanation, thank you!
Wow. This is the best explanation on this I've heard so far. Great job and thank you! 😊
It wasn't, her hairy arms were distracting me from being able to focus
I spent the last hours trying to understand what this nobel prize was really about and the closer i could get to it was with this video. Thank you very much
This person is a terrific teacher and explicator of very complex ideas with clarity and ease. Brava!
Nice production quality - excellent speaker - great engagement! This video presents an introduction to Bell's theorem. Great work!
Beautifully explained. The fact that we can actually do this experiment with Qiskit is just awesome.
To each his own, of course, but I happen to disagree. Here is a much better explanation (IMHO) by Sixty Symbols: ua-cam.com/video/0RiAxvb_qI4/v-deo.html
@@robinswamidasan Just had a look, indeed, it's a remarkably explained
@@robinswamidasan oh by the way, how did UA-cam allow you to post a URL, don't tell me it's quantum computing🤣
@@robinswamidasan I like this too.
I did my undergraduate thesis on Bell's Theorem and loopholes in experimental tests of the theorem.
I was pleasently surprised to see Alain Aspect winning the prize because I read a lot of his research.
I am curious to hear more about quantum-tunnelling experiments that seem to show information being transmitted faster than light. Particularly since some of the claims that what was being transmitted (a piece of classical music in one experiment that I recall) was not really “information”, seemed just a little bit dubious.
I have a PhD in quantum optics. Why should Bell's Inequality be the weirdest theorem in the world? It makes perfectly sense and is no stranger than other parts of quantum theory.
You have proven you might now know you did not know what you thought you might have known or not known. As well, your words, it’s miraculous. Good work!
The fact that I can test Bell's Inequality online is crazy!!! Very cool. Makes me want to study computation theory.
This speaker is great. She is able to communicate clearly and make it simple to understand and relate to. Thanks for the great explanation.
The clarity is due to the writer of her script. If she wrote it, applause. If not, she is still a great presenter.
Thank you very much for such a wonderful explanation. I wonder if these experiments ultimately confirm that there is "something" that we are not taking into account. And that is precisely what we could call "hidden variables", or better, "unknown variables", because in fact we know what happens but not exactly why.
Well done. I understand some of it; I am still learning. At 77 it is difficult to comprehend since everything I learned is now passe. The universe is joyfully weird.
everything that you learned that was true is still true, nothing is wasted
My favorite line: "It's not just weird on paper, it's weird in the real world."
Well, if a Higgs likes it...
12:26 "...us in the field..." are we not all in the field, seeing a few wave-tops and thinking it reality?
Dude, where's my boson?
Thank you, Olivia. I didn’t understand half of it but your presentation allowed me to grasp some of it. 🤣 I hope you’re teaching somewhere; you have a wonderful, open style of communicating ideas clearly.
And you still understood 10x as much as me
lol She literally said nothing. Suppose that instead of Bob and Alice making measurements, we let Victor keep a record of the properties of the particles he sends to them. Where then would the 2.8 figure come from? Clearly, Victor is biased in some way.
They would still have to be measured in order to have a record
Yeah Victor is suspect...He likely voided his honesty by being a supporter of donald duck, he can't be trusted. His maga hat is definetly on a few snaps too tight...That in and of itself makes him untruthful, like his esteemed(he thinks)leader...Yes I'm sorry to tell you but, in the spooky action at a distance of quantum theory makes Victor nothing but a liar, so vote blue and save our local reality!!!...lol
She can communicate ideas clearly but you didn't understand half of what she said?
Excellent video, with very clear explanations. Thank you!
Thank you so much…🙏🙏🙏 way above my maths/ comprehension at near midnight.., but a huge privilege to have the theory behind a noble price explained🙏🙏
I enjoyed this very much! It''s my first video watched from this channel, I'm a new subscriber!
Enjoyed this exposition, and I'm far from being a physicist or understanding the nuts and bolts of quantum mechanics. It adds to the many, many things I know I don't know enough about and that no matter how much I try I'll only ever have a tenuous grasp of!. Every day is a school day.
Thank you for that! All the mysteries we have yet to uncover is exciting!
Best explanation I’ve listened to so far. Thanks
In the first set-up, Victor sends two non-entangled particles/qubits, one in Alices' direction and the other in Bob's direction.
The entangled pair, had selected a state before any were measured, else they would not have become entangled. The uncertainty is entirely because of the problem of measurement. It is a fundamental problem, not something to write into a theory. The universe operates completely well outside our observations or measurements. We need a whole new approach.
I feel like I've been waiting my whole life for this.
Wow great walk through.. Olivia should start a lecture series on QM stuff here on youtube. Really cool!
Whenever someone names the character in their example as Alice it reminds me of Leonard Susskind :D Great video!
Masterfully done. Thank you!
What is interesting is during '50s, '60s and even '70s working in quantum theoretical field and challenging the Copenhagen interpretation was a kiss of death for your career. That was clearly stated by Clauser himself. Even John Bell, after writing his not so famous at that time Bell's theorem, left it for like 20 years and picked it only later on during 70s. This behavior was generated by the "Shut up and calculate!" mentality that arose after WWII.
I loved that ending. It felt like a heartfelt and genuine thank you to the Nobel prize winners.
Also Olivia, you’re doing pioneering work in quantum computing. The rest of us thank you for the applications that will come from your work and many of OUR future jobs.
Appreciate it!
Back in the 70s, there was a physics Nobel laureate in my meditation class at Cambridge. Afterwards we had tea and a chat, and someone asked him why a scientist was drawn to this mystic practice He replied: "Oh, we're all mystics at the Cavendish - and once anyone begins to understand the profound weirdness of reality the way that we understand it, they would become a mystic too!".
What’s “the Rutherford”?
@@shyampadmanabhan4171I misremembered - it's the famous Cavendish Lab where Rutherford first split the atom.
Will edit.
@@tullochgorum6323 if you could go back in time to stop Rutherford splitting the atom , and prevent the development of what Russia is threatning to use today.....would you stop Rutherford, or not.?
@@tullochgorum6323 that is a great story. On a technical note, Rutherford didn't split the atom. Splitting the atom happened the year after he died. He did a lot in physics, though. Thank you for sharing :)
@@fierce-green-fire8887 Thanks for the information on Rutherford - I'd better read it up because I seem to have misunderstood something about his work.
As you will have gathered, I'm very much a lay person when it comes to the mysteries of physics!
The more interesting idea is that the measurers themselves are in a superposition until they measure one of the entangled particles, which collapses them into a state where both particles have been measured.
When you explain the fact that these particles are not transferring information faster than the speed of light it's still a little confusing. It's mentioned that the particles are entangled and their wave functions become one. It also mentioned the the particles are sent to Alice and Bob before the measurement. So, because entangled particles consist of the same wave combined wave function, they can be thought of as the same quantum object. When the two objects are transferred to both locations at less than the speed of light before the measurement then the information traveled at sub light speed to their measurement locations. Then when a measurement is made of one of the particles, then the combined wave function or quantum object collapses into a opposite values for both particles at the same time. The fact that you can have an quantum object that is essentially in two places in once until measured and it breaks into individual particles again is really the crazy idea here.
Great explanation of Bell's results. After reading Wikipedia's entry on his theorem and watching UA-cam videos, I only finally understood your explanation! I've got a few questions from curiosity, and, to ensure I'm on the same page:
1) does normalizing mean we make a value easier to work with by first converting it to a simpler number like 1? (or -1)
2) is the result at 9:00 inviting us to choose between 'faster than light' or 'indefinite until measured' when you say "it is incompatible with local realism, so either: something is moving faster than the speed of light, or these particles do not have definite values before they are measured"?
Or, it it simply saying: the result cannot be violating the speed of light, so it must mean that the values were indefinite until measured? (which means it's different than classical)
3) does classical include Einstein's relativity? (in context of your video)
4) when Bob and Alice know they received a particle, isn't that by interacting with it so it'll already be collapsed? (in other words there isn't any way to have or carry an uncollapsed particle after knowing you received it)
1) Normalizing simply garantuees you that you are working with a probability distribution - one where all values sum up to 1. Which is important when talking about probabilities.
2) Not really. This mechanism of entanglement is probabilistic in nature. You can not chose the message youre sending. On that topic, there is the no-communication theorem and others if you want to read more.
3) Relativity (both special and general) are classical theories, yes. Note that this is simply a classification and basically, anything non-quantum is classified as classical.
4) I am actually not exactly sure on this. But I think its possible to interact with a system such that is collapses into a subsystem, still being able to collapse further. So I guess it depends on how you find out that you received it. And even if thats wrong, there is no problem here, right? If the measurement you are interested in gives you a result, you know that you received a particle.
Thanks! That was super clear. I never really knew what Bell's Inequality was claiming, only that it sealed the truth of non-realism. For me, the double-slit experiment was my introduction to non-realism. I just read that the "single electron" version of that experiment (which is the version that blew me away) wasn't done until 2002, years after Einstein died. So he never got to see that. Now I understand how non-realism was established in a more thorough way using the violation of Bells Inequality. I also don't feel as disappointed in my high school physics teacher whose explanation of the particle vs wave nature of light left out telling us about the underlying quantum weirdness it suggests. Since that was before 2002 he couldn't have known . Tying up a lot of loose ends here ...
> only that it sealed the truth of non-realism.
It didn't the explanation is wrong. It only sealed local hidden variable theory one of many local realistic theory. There was and it is still a lot of research on a local realist description of quantum mechanics.
It most certainly did not "seal the truth of non-realism". You can have realism or you can have locality, but you can't have both. Remember that these words have technical descriptions in the theory so don't load other meanings onto them.
@@coot33 Maybe I should have said the "reasonableness" of non-realism. "Truth" is a pretty high bar.
@@nehocm123 You can have both. Deutsch worked on it in the early 2000. There are even more recent result of making local-realist description of quantum mechanics. That is the point. It's unbelievable to some physicist but the bell theorem doesn't exclude it. If you want i can send you the link of papers.
@@coot33 I am familiar with the many worlds escape from this conundrum and I will grant its formal consistency but until one of its forms is shown to be testable, at least in theory, I would prefer to give up locality and keep realism. This is of course a philosophical stance and I don't begrudge you or Dr. Deutsch for believing otherwise. Keep in mind that the non-local phenomena we are discussing do not involve FTL signaling.
I also suggest that a likely more fruitful approach is work on objective collapse interpretations and the nature of time and entropy in spacetimes with realism.
exceptional delivery. Nice work, Olivia.
EXCELLENT PRESENTATION 👏 ...thank you 👍.....super impressed with how you presented the ideas and I see others are as well so I am not alone in that regard
I have been struggling to understand Bell's theorem for years and I'm afraid that this presentation leaves me just as confused as before! But what I would love to know is whether there are any practical applications of these strange phenomena.
Yes, quantum encryption
@@evihofkens9530 I just read what Wikipedia says about that and frankly I couldn't understand it at all! Thanks for the info, anyway!
Philosophically, quantum physicists have proved a negative!
You can prove that men and wolves exist, but you can't prove that werewolves don't exist!
@@carlgrove8793 «@Evi Hofkens I just read what Wikipedia says about that and frankly I couldn't understand it at all! Thanks for the info, anyway!»
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Dear friend, imho the reason you cannot understand it is that of being sincere and honest. If you want to understand it in a way many others understand it, you should (re)read The Emperor's New Clothes. Btw Clothes that were made using bits that had jumpy levels of sawing energy coming out of cryptically nested sub-dimensions of the inner quantum not-space.
The main problem I have with this video is that she completely dismisses locality and emphasizes the experiment disproved realism when the results of the experiment show neither locality nor realism is true in quantum mechanics. The information of entangled objects does travel faster then the speed of light. While the persons in the experiment cannot communicate faster then light, the entangled cubits can which means the instant one person knows the state of one cubit, the other knows instantly what the state of other cubit is.
Fantastic video but I would say it is missing one thing. For Bell's theorem, he also assumed statistical independence of the system, that is P(x|ab) != P(x) where x is a specific event of a quantum particle and a and b are measurements taken of the particle. In other words, if the "choice" the particle makes with regards to its waveform collapse is based on the measurements that WILL be taken of the particle in the future, then none of Bell's theorem, including the inequality, apply. I think this is important to think about, since no one has ever proven that statistical independence actually holds.
It's turtles all the way down.
My personal take is that measurement information retroactively determines agreement on state. I’ll throw away causality in hopes of a deterministic reality.
Re: Turtles. I thought it was elephants😢
Superdeterminism follows?
This is an awesome explanation of the Bell's inequality! Thank you for being concise!
Thanks Olivia and the rest of the team. I'm recovering from series of mini strokes. I use videos such as yours as weight lifting exercises. The brain is a muscle. It needs the exercises you kindly provide. Thanks again for the knowledge and a little bit of befuddlement!
Thank you for so clearly explaining to this sublayperson the meaning of this NOBEL event.
Sublayperson sounds similar to my self designated 'amateur layperson'. Maybe in a few years, already 67, I can become an experienced amateur layperson'. 😂😅. I did really like this explanation and surely wouldn't try to paraphrase it.
This is so well explained - grabbed my attention throughout! You are such a talented presenter :)
Thank you for a clear explanation. If you measure one particle, is it true that the wave function collapses for the other particle and that can be detected (perhaps through something along the lines of a double slit experiment)? If so, how come that is not a way to communicate (measuring the collapse of the wave function)?
The UA-cam algorithm recommended this video to me on the evening after I read the chapter on Bell's Inequality in Heinz R. Pagels's 1982 book "The Cosmic Code: Quantum Mechanics as the Language of Nature." I'm tempted to joke about attributing the coincidence to nonlocal causation or spooky action at a distance -- but instead will just recommend the book, despite its age, as a highly readable and enjoyable introduction to the subject. The description of the standard model in the second half of the book has been overtaken by events, but the first half, discussing the historical development of quantum mechanics and thought experiments illustrating concepts like indeterminacy, complementarity, and the observer-created reality, has not lost its luster after 40 years.
That presentation was interesting and your delivery was appropriately technical and charming- a combination of science with humanity. Thanks-
Thanks for the explanation. I had heard of Bells theorem but this helped me understand it better as a non-physicist. The idea that realism does not exist sparked many of my own "thought experiments" about the nature of reality and the universe. I think we may be close to unlocking some of the secrets of reality itself, the consequences of which we cannot comprehend at this point.
Can’t disagree with slip’s conclusion here but it’s looking to me like either it’s gonna be a Trojan horse orapandoras box. Third favourite has to be the lair of the Minotaur with or without heroic intruders. Here’s one I’ve never wondered about much until now; what did the Minotaur do if they accidentally left it’s lair unsecured?
But it's not "reality" like a normal English meaning of that word. The point is just that we've disproved the idea that "measurement" tells you about properties of a system that existed before you took the measurement. I'm not 100% sure why the word "reality" is used in this way, not the word I would have chosen, I think. I think it had something to do with a quote from the EPR paper.
Wow. Very good explanation. I was waiting for the "usual" error that screws up the logic.
It didn't come. None of us really know what is going on, but in terms of what we theorize - this presentation is wonderful.
Thank you for putting all the effort
Great content... thanks for sharing
There are so many explanation out there of this last Nobel in Physics than either oversimplified the issue to the point of being wrong or they enter into so many details that I need a PhD in Physics to have any chance to get something out of them. However, this explanation hits the nail on the head. Brilliant.
I still dont get it
@@pavelvedernikov8502 Then you're probably a bit like me. I can grasp a lot (actually most) of the concepts and theorems of physics when it's explained to me in words. I'm just not a beta person by nature. Therefor I've always struggled to understand the underlying proof. Which of course is always expressed in the beautiful language of maths. It takes me a lot of effort to actually understand those equations. Just rewind that part of the clip a couple more times and try to do the equations step by step with her. It eventually clicked with me.
Really well explained - thank you. Einstein is right in the sense that there is still a mystery here.
very nice explanation and video, well done! It helps me , thanks.
You’re a great presenter! Thanks!
This satiates my queries so much while also firing so many neurons for further inquiries.
Brilliantly communicated the phenomenon 👏
What a spooky good breakdown of the physics. Thanks a for an excellent vid! 💖
Superb clarity. TY
This is fascinating! Quick question: is there a specific "max speed" beyond the speed of light, such that the 2 ~ 2.8 equation would actually balance out correctly? Like, if we pitch lightspeed and keep realism, do we get a specific number for max speed beyond our (easily? currently?) perceived max?
Um, idk the answer to this question but i think the implications of this experiment is not that the speed of light is violated but that local realism is violated. Although i believe there was a study done by swedish physicists with mirrors and virtual photons that postulated that the speed of light was not in fact a constant but relative to the number of subatomic particles in existence so that it appeared constant.
@@Ben-rz9cf See yeah, exactly. I'm just wondering what we can gain if we throw the speed of light out instead.
Sports almanac for future gambling endeavours
Planck speed
@probablyup I was so immediately excited after reading this comment that I googled to get reading and now I'm not even sure if I'm being punked or not, that's how hard it is to learn science online in current year
Love Bell’s Theorem-so simple, yet so hard to grasp. (I’ve been trying for 40 years. Getting there.🤨 I think.)
Quantum particles can become entangled, that’s it really
Where does this equation come from? Is x and y spatial coordinates or base values for cubits? The circuit calculator? Is it sufficient to calculate a simulated logic/diffraction gate using entangled particles for a computational hologram?
I love your style of presentation. So natural.
As a lay person who studied analytical chem and no physics courses, I think I'm following. This host is a great science communicator.
As a follow up vid, I am curious to see how the experiments of Clauser et al were conducted. An overview of the instruments and data/analysis that resulted would be much appreciated.
She's an incredible presenter of information / data. Very well explained despite the complexity of the material.
@6:29 "it really doesn't matter where this quantity comes from" - I would like to know where the equation comes from.
That‘s what I thought as well.
A very nice explanation, kudos for clarity. But I thought that Bell also recognized the need for measurement independence i.e. the notion that the choice of detector axes were made independently by Alice and Bob. If their choices are correlated, as in super-determinism, it provides yet another route to violation of the Bell Inequalities, albeit no less "spooky"
such a clear well-presented explanation
Intelligent speaker and explained in a down to earth manner even a layman like me can understand. Thank you.
I would love to spend years hanging out with you and talking about so many other things. You did a great job with this.
Bell Test (CHSH) does not describe what happens in QM. Alice gets the particle either X or Y and Bob gets the particle either X or Y. But you need to prove that Alice's X is the same as Bob's X plus Alice's Y is the same as Bob's Y. This is near impossible for distances over say 5 meters. Alignment error increases with the separation distance. Alignment also varies with time due to variations in the local gravitational field bending space. So yes, CHSH is great on paper. But in reality???
Legit, easy to follow, thorough. Nice. Thanks for explaining.
The Bell's inequality experiments are great! Probably a good choice for the Nobel Prize. My amateur guess is that they show that reality is nonlocally interconnected. Maybe with waves. Stephen Hawking wrote that there might be only waves, and that particles with locality are just our interpretation of the underlaying waves and that there isn't even any need for uncertainty in quantum mechanics.
I have always subscribed to this interpretation of reality, as it is anchored in relative Spatio-Temporal Unity… however, it has to be justified and proven first for it to hold any substance in the community and society as a whole
This explication *rocks* ! So well done, so well conveyed.