Angular momentum is always conserved in the universe. Fundamental particles have angular momentum. As far as we can tell Quantum mechanics is inherently probabilistic so when you measure the angular momentum of a fundamental particle the result is random. When these two meet it seems that for angular momentum to always be conserved in the universe when the angular momentum of a particle is found another particle must change to be opposite of what it is, other wise angular momentum would change ever so slightly, and this is what we do observe with particles that are Quantum entangled i.e. the pair that change to always be opposites
It is a property of a particle. We do not observe it in our macro world, so we do not have a word for it. So they called it a spin because it was the most appropriate word they could think of. It is hard to explain something you cannot observe by your senses, only the experiments give you information about it.
It’s easier than you may think. Mathematically if particles would have initially coordinate their spins it would give different result as opposed to what happens in reality. Meaning, if you throw a tennis ball on the wall on 60 degrees and the pair of that ball must behave exactly opposite then it should be 60/90 times or 2/3 of the time. If they calculate several possibilities of it like if 75 degrees 75/90 vs 25/90 etc then they compare it with what really happens it gives different result. If expected opposite percentage of spin is not equal to actual percentage measured in different angles of measurement then particles don’t have predetermined coordination. The only argument against thus may be that our math is incorrect, meaning math or probability as we perceive is completely irrelevant in this case. And I think Einstein could argue his case too. If there’s no specific “one” in this case then how can we say what would we expect from particles in the first place if they talked with each other before measuring. One particle can be on different places at the same time. There’s no one and zero in quantum physics, there’s no math here so talking about probability makes no sense.
@@johnphantom Can you make some kind of video or picture explanation of that thing. I am quite intrigued but I don't think I understand it properly. A video or picture will definitely help! Thank you!
@@abdullamasud4278 I think the best way to visualise it would be to model the simple calculator in Minecraft. Unfortunately, I know nothing about that application. I am looking for someone to help me.
I just sat down, listen intently to the contents of this video, and suddenly 9 minutes have passed without me knowing it and the video ends. What a brilliant presentation.
I remember watching this video when it was released as a first year uni student. Now I work with quantum entanglement on a daily basis and this video was one of the things that piqued my interest in this field
Quantum physics is the truth of universe and lie of human consciousness saying that it does not need any observer or audience it knows its nature and truth
Specially in quantum entanglement universe is constant it knows what is up or down so where ever the particles go their nature is pre determined its just us making it complicated by knowing it after so many years of evolution
Aye, good for you man. I remembered when I first saw this video I thought to myself how crazy it is that we were even able to test hidden variables vs. quantum stuff. It was so abstract, and yet the experiment basically settles it. Kind of awesome
Another applicable principal to spooky would be "vibes". Ever "vibed" with someone or say the same thing at the same time? That's one other application to spooky.
I remember watching this video when it came out back when I had just finished primary school, I barely understood anything. Now rewatching it, as I'm in the midst of my Quantum Mechanics course in Uni, it's both nostalgic and satisfying finally being able to make sense of these concepts. Amazing video, thank you!
@@PDBisht in Europe when we say primary school we often mean primary and middle school so from "i just finished primary school" I think he meant something like just beggining High School And in my country high School is 3/4 Years so it is possible to get into University after 4/5 Years of finishing "primary school"
@@itiso1123 ah! I see here primary usually means 1-5 years of school after doing your pre-school and then 5 years of middle school after that 2 years of high school then only you'll able to enroll in college/university..
I think the difference can be described as the orbit of the earth around the sun and it’s daily revolution. Both are a type of spin; I think he means to say the spin of the particles is more like that of earth’s annual revolution
Heisenberg and Schrödinger get pulled over for speeding. The cop asks Heisenberg "Do you know how fast you were going?" Heisenberg replies, "No, but we know exactly where we are!" The officer looks at him confused and says "you were going 108 miles per hour!" Heisenberg throws his arms up and cries, "Great! Now we're lost!" The officer looks over the car and asks Schrödinger if the two men have anything in the trunk. "A cat," Schrödinger replies. The cop opens the trunk and yells "Hey! This cat is dead." Schrödinger angrily replies, "Well he is now."
@fly med I never heard it before! So I'm okay with it. Hey, how about people who were born after the 1960s? They shouldn't hear it because you already have?
It's very complicated but I find this fascinating. It's one of those educational video's that you need to watch a couple of times before you start to understand.
"In order to understand it we must first understand spin. All fundamental particles have a property called spin. No, they're not actually spinning." You lost me. (0:41)
Thank you to those trying to make sense of this! For clarification: 1. We know the entangled particles must have undefined spins before we measure them because if they didn't they would sometimes give the same spin when measured in a direction perpendicular to their well-defined spins (and they never do). 2. We know the entangled particles can't have hidden information all along about which spin they will give in different directions because if they did we would measure different results at the two detectors >5/9ths of the time and we don't - we only get different results 50% of the time. 3. We can't use this behaviour to communicate faster than light because we can only pick the direction to measure in, we can't force the spin to be up or down - and it will be random with 50/50 probability. When the two detectors pick the same direction to measure in the results at one detector will be random but the opposite random of those measured at the other detector, which is a bit spooky.
As its a 50 50 percent chance we cant use the data of up or down but they still gets data so using time intervals we can. a 1 is two ups or downs with a gap after and a 0 is one up or down with a gap after therefore it doesnt matter if its up or down Can anyone see any problems
isaac heaton It is true that random information is data, but the data in this case isn't originating on either side. We can't tell a particle to be measured a certain way. Even if we had an agreement on which way we should measure them (and in what order), there's no way to impact what the other side sees.
His explanation of 9 years ago is among the best I've heard yet. Every time I think, now it's making sense, hidden variables just keep popping back into my thinking. The problem reminds me of trying to explain why a mirror reverses only in the left/right direction and not in the up/down direction.
+beefcake It's different because there is no way you can pre-assign the spin of each particle to get the experimental results for all possible orientations of your spin detector. If the detectors were always in the same direction you'd have a valid point. But they are not. When you "do the math" you end up with the Bell inequality. If the inequality is violated, hidden variables (the pre-assigning of the frequencies of all possible outcomes for all possible detector orientations) are ruled out. Experimentally it's violated, which means it's spooky. And QM correctly predicts the results.
+Polly The Parrot at least you are educating yourself about something that passes most people by without notice instead of learning about old texts that have no real need in today's modern times
Brunneis Ursus Hey, careful what you say about Shakespeare. I wouldn't say there's no need for his works in modern times. Most are antiquated and boring, but he's the father of entertainment. If you're going to study acting or playwriting, you need to understand the origins of the field (That apples to screenwriting, too).
***** there is a theory that Shakespeare didn't even write his own work, some believe that there was a group of writers that wrote "Shakespeare's" plays and then gave credit to him, look it up, im not making this up, i learned about this in my senior year in high school, he did't have any of his own work, after his death they searched his home and he didn't even have a library that he would have needed to have knowledge about the ancient world or other places around the world, he also never really spoke about his works and was vague about how he came to write them...it makes you think
I've always struggled to understand the experiments you mentioned regarding measuring entangled particles, and I found your visual representations to be very helpful.
This video is straight fuego 🔥. Veritasium always explains things so clearly and carefully. I'm so grateful for all these dope science educators on yt so I can keep learning even after graduating. Cheers!
@@ananyasrivastava5128 It goes like this. If you think you understand quantum mechanics you have not understood quantum mechanics. Quantum mechanics we can do but to understand its weird nature is not easy for our deterministic brain.
Following his explaination I could communicate faster than the speed of light (What did I miss? Please explain because this genuinely bothers me) - Person A gets 100 Particles with spin "up" and Person B gets the 100 entangled partners of those having spin "down". - Person A and B are many Lightyears apart - Person A and B have aggreed on measuring the particle's spin regularly at every odd and at every even second respectively (always in their spins current direction) Sending the message: - A can measure one time only the spin of their 100 particles perpendicular to the usual direction thus changing the direction of the 100 spins but also of the entangled ones. - B doesn't know yet that A has measured perpendicular and does the measurement still in his assumed current spin direction. BUT now on avg. 50 spins which were originally "down" will have turned into "up" - Thus B will know that A has measured perpendicular.
@@csabadunai3760 the problem is we can't make A spin "up", because it has also 50% chance of up or down, so we can't send message to B as we can't control the spin of A nor block particular spins of As. Hope you understood
Agreed. I'm surprised at how many commenters didn't get it. It seems pretty straightforward: particle spin can be up or down, but without getting together to share notes you can't tell whether it's significant or not, so you can't use this for FTL communication. It just begs the question of what's really going on -- which is what good science does, because good science not only provides answers... it breeds more questions.
Mee It is a property of atomic objects which has no (known) equivalent at our "scale". I think calling it "spin" is also confusing because people immediately relate it to our idea of what spin means when it's something different.
TheShreester what do you mean by no known scale? If we can measure this property of "spin" surely its something that can be described in terms of what it is ..
I said "no known equivalent at our (macro) scale" because there isn't one. The idea that particles have spin is an analogy intended to help us visualise what is going on.
Thank You so much for the short but very clear explanation at the end about why faster than light communication is impossible using entanglement. I finally understand something I have been trying to understand for years.
Why did you hope to be dumb at all, in the first place? ( being exact with the English language on, “I’m dumber than I’d hoped” means you had a hopeful thought on being dumb.lol).
@@mattstevens4192 it could mean that he had hoped to understand spin but doesn't so he is dumber than he hoped. if you understand spin, you're pretty smart.
@@mattstevens4192 bc he's being modest by assuming he was dumb all the time, but not "that dumb" assuming that and making the conclusion about the market of this video actually makes him smarter than he thinks he is. It is the not-dumb actually smart person that maybe don't realize he's smart dilemma. Sort of
I like the idea of living in a "probabilistic" universe that just gets concrete when things are measured. So, this entangled particles don't need to exchange any information. It's just the observer who, by measuring the spin of one of them, enters into a specific universe in which the other particle is (and always has been) consistent with the measured one.
@@sambennett996 I googled what you said for clarification and kept finding results of "babies" and "gender" and "quantum physics"...then I realized "baby" wasn't part of the term. 🤭
This view isn't as feasible as living in an idealistic world, it's an odd suggestion in favor of materialism that in order to be possible there has to be multiple earths with every single different probability and combination existing on it. But there are billions of billions of humans, with trillions and trillions of cells, all of which go through this same process. Meaning their are billions times billions times billions times trillions of other earths, which is a much more convoluted answer than something that can simply just be explained by idealism which is that reality is a mental construct and doesn't exist independent of observation.
Try watching it a few times. And/or take notes. Maybe look up another individual's explanation of Bell's inequality. Some folk understand one teacher while another understand a different teacher coming at it from a different viewpoint.
I had studied physics and did not receive such a good explanation during studies. In particular the bell experiment and why there are hidden constants. In the video it is a bit fast (should watch 75% speed 2 times and pause and ponder) but still extremely good. It is not easy, but essential, and the explanation is to the point.
Let's say we send a spaceship a lightyear away. On board, there's one particle and we program the spaceship to measure the spin at a specific time. If the spin is up, it destroys itself, if the spin is down, it keeps on flying. If we measure the spin of the other particle here on earth at the same time, we immediately know whether the spaceship just blew itself up or is still flying - hasn't then information been transmitted?
A hare does not aim accurately as we say in Sweden. No information is carried faster than light, instead the information is carried within the spaceship so to say, more precisely the information how to act upon a certain spin. It is apparent if you think about a little bit closer, the ship could stop to function at any point in the journey and the self destruct could fail for any reason, then the information we have sent with the spaceship ceases to be relevant and no faster than light indication of this is possible. If this happens we can very well be reading a spin up, assuming the spaceship has auto destructed as planned but until some sort of light speed information like electromagnetic radiation reaches us that tells the real tail we are only guessing, we can't know. You can think of it this way, if we are to go through a labyrinth both at the same time we can entangle our self by saying when given a choice I will always go left and you will always go right. As soon as we make our first decision we lose all knowledge of each other and needs to communicate somehow to know anything about each other. I can however with this information follow you and find your entire path but I need to get this information in real time.
You mean: you have assumed that the spaceship blew up based on some expected cause and effect however you couldn't testify in court with certainty that you are now down one spaceship.
there is a 50/50 chance that you will watch it up and 50/50 chance you'll watch it down. and the results will be different 5/9 of the time and so the results are different only 50% at the time.
INCREDIBLE VIDEO!!!!!!! I knew this was not going to be easy to understand. So I cleared my mind, sat back relaxed, and gave all my brain to understand this and also watched it 3 times, and I am really happy to totally understand what all you said. For me, It was my first video about the Quantum entanglement and you did a perfect job in keeping me enthusiastic about this SPOOKY topic ;D
I totally agree with you man, I’ve watched it years ago and didn’t understand well but I came back more intelligent and now I totally was able to understand him, I had to pause and rewind so many times 😂
Bell's inequalities are brilliant and mindblowing, with implications that go deeper than most people realize. They tell us that either locality (things are only influenced by their immediate surroundings) is wrong, realism (the moon is there even when you're not looking at it) is wrong, or both. Their most important lesson is that the things you assume, the things which seem like common sense, must themselves be subject to question, because reality might not agree with your assumptions.
No, macroscopic objects like the moon interact gravitationally and electromagnetically with their surroundings and are thus always present whether anyone looks at them or not. "Not looking" means no interaction. Only quantum objects are small enough for that to happen.
***** Realism, to a physicist, means that the properties of a physical system are mind-independent. In most cases, I'd be with you 100% on not applying quantum phenomena to the macroscopic world. But realism isn't a concept from quantum mechanics, it's all over classical mechanics. And we can't say that little things don't exist until we measure them, but the big things composed of them do. If we accept the mainstream interpretations of QM, like the Copenhagen interpretation, then anything not being measured isn't there, but instead has only a probability of being in any given state when we do decide to measure it. That's weird. But the universe doesn't care about what we're comfortable with.
Matthew Prorok My point is that macroscopic objects are always being measured. For them not to be measured, you'd have to turn off the moon's gravity and make it not reflect any sunlight, and it would also not have to block cosmic rays etc. Macroscopic objects have too many effects on the environment to behave quantum mechanically.
***** Well, this gets to one of the more difficult points in quantum mechanics, what "measurement" means. That's what Schrödinger's cat is about (which seems relevant here, since it was in making this analogy that he coined the term "entaglement"). What you're doing here is asserting macroscopic realism, which is fine. You can do that; plenty of people do. But it's still an empirical claim that's subject to testing, and Bell's theorem suggests that it could be wrong. As do some experiments involving macroscopic quantum phenomena (i.e. lasers, superfluids, and supercondutivity). I'm not saying that macroscopic realism is wrong. I don't know whether or not it's wrong; nobody does, which is why it's still a topic of research. I'm saying that we can't assume it's right. And if it is right, then Bell's inequalities tell us that locality must be wrong. (Or, alternately, that we have to sacrifice counterfactual definiteness, the ability to speak meaningfully about the results of experiments we haven't performed yet, as the many-worlds interpretation does.)
***** From the moment it pops into existence, a particle is affected by gravity from everything in the (at least visible) universe, and its tiny gravity would affect other nearby particles and bodies much sooner than the entanglement-breaking measurement takes place. So does gravity not count?
Its incredible, unknowable things like this that make it fascinating to be alive! It's like, you want more of it, can't handle the reality of what is already out there , yet you yearn for more! Thank you sincerely!
@@LuisSierra42 Generally angular momentum is calculated about a point in space. So, even a particle travelling with a constant velocity, let's say in a direction parallel to the x-axis, has angular momentum with respect to let's say the origin. What angular momentum means here though, is a mistery to me as well. I need to learn more...
Jesus: SpinUp, Satan: Spin Down. There. Yin & Yang....or, does that only create more questions such as religion is only the result of polarity between pairs of matching particle probabilities...the world may never know. :)
I was literally just watching Only Lovers Left Alive again yesterday and them talking about Entanglement Theory and Einstein’s Spooky Action at a Distance and was trying to look up information on it yesterday but every description I found went over my head. In sweeps Veritasium to save the day once again!! Lol You rule bro. Keep it up!!
@@ChristmasEve777 Always a condescending republican in the comments... You should know that everyone is annoyed by people like you. You give republicans a bad name. Luckily my republican friends are not this way. Please leave politics out of science
@@steffenjensen422 Always a boomer in the comments. you should know that everyone is annoyed by people like you. Luckiely I'm not a boomer, so I can actually make fun of you lmao. Jokes aside, i hate people that get mad because someone made a silly joke.
@@heisenmountainb6854 I understand that me getting mad instantly is annoying itself. But I think it's warranted, since this kind of "little joke" is exactly why many people in the US can't communicate normally over party boundaries anymore and you'll probably agree that this is a real problem. After all, a country where one side will just always try to hinder the other won't progress a lot anymore and will grow weak. Maybe you're right and I'm overreacting - but maybe this is why we can't have nice things.
I'm more confused than I was before the presentation. There are so many counter-intuitive issues raised and so many statements that need explaining, rather than just having to be accepted as self evident.
@@tabby73 the general genius idea is that apparently, if the information for what spins particles must have in which directions is predetermined (or determined at birth) then whatever that rule is, no matter how complicated it is, it must yield some ratio results for all three directions. For example, 50/50 at a given direction. So the great idea is, no matter what the rule is, if any rule exists, then the experiment should not match what we really get , which is 50/50
There is a third interpretation : when you get the results of the second experiment, you are still measuring a quantum system (whose proper description depends on your results). This interpretation preserves locality, but is observer dependent. It is called relational quantum mechanics.
The mainstream media seem to have an issue with Social Media. Watching YT has engaged me with science more than since school 40 years ago. Stuff like this video has re ignited my mind much more than hearing sound bite news bulletins of fear & misery on repeat every 15 minutes….
so does a quantum particle spin vertically before we choose to measure it horizontally @1:07 ?? I thought in this analogy it wasn't spinning at all UNTIL we choose a measurement?
I just love your videos. You do an amazing job of taking complicated interesting concepts and breaking them down with words and visuals that allow for those of us without formal educations to understand science on a much deeper level than we ever could. I'm tempted to suggest a topic for a video, but you keep coming up with such great ones that I'd rather just be surprised by the awesomeness you'll come up with next. Thank you so much for your hard work!
You can go checking EPR paradox or Nicolas Gisin's work (quantum teleportation ?) sorry I'm a french speaker so... I can't really explain anything (plus I'm only 18 x)) just ... go check PS : EPR paradox IS what "Einstein proposed", but he wasn't alone thinking about quantum entanglement so it is proper to talk about Einstein-Podolsky-Rosen
Am I getting dumber or was this WAY harder to grasp than any other Veritasium episode? The video ended a few seconds ago and I have no idea what I just watched. Thumbs up either way for using your 2 million subscriber channel for something like this, rather than yelling over video games or whatever ;)
wooohooo! Yeah this one is way harder than most things I've attempted. I actually made the first version seven months ago but it was impossible to understand, even minutephysics thought so. So I remade it and tried to make it more understandable. It's definitely better than the original.
Veritasium It can't be easy to explain something no one really seems to have figured out yet ;) Whenever I watch / read something related to quantum mechanics it always just comes across as people thinking out loud. How much of the things you've said here is fact / theory / hypothesis?
Veritasium I think this is the best explanation I've seen of Bell's inequalities ab initio. I work in quantum information though, so I'm coming from the perspective of someone who already knows the material (nevertheless, that means I've also seen a lot of attempted explanations, including some of my own).
racoiaws This is fact, experimentally verified time and time again. The mathematics of quantum physics is well established; the only part people have trouble with is breaking down concepts into everyday language. This should be no surprise, because quantum physics explores regimes which are very far from everyday. We shouldn't expect our spoken language to have the capacity to explain it adequately, nor necessarily for these things to be intuitively graspable. Quantum physics is possibly our most successful physical theory and none of its predictions have ever been proven wrong in experiment (and believe me, they've been tested).
Bell's Inequality is one of the harder theorems to understand in QM and one which most students struggle. Derek was brave to even attempt an explanation without using any maths! Putting this stuff into layman's terms is difficult but he seems to enjoy the challenge!
My questions: 1. How can a particle not spin if it has angular momentum? Isn't angular moment the definition of spin? 2. The guy is spinning the same way every single time after he goes through the cardboard, how is the spin changing? The only thing changing here is his orientation. 3. According to your equation, the "spin" (orientation) should always be up in the vertical cardboard experiment, but you show that it can be down?
Entanglement is a property of waves if you drop a pebble into a pond the ripples will expand out from their centre. They will have the same up or down movement as they expand out at the same moment in time, they are entangled or synchronized. Quantum entanglement can be explained if quantum mechanics represents the physics of ‘time’ as a physical process. In this theory the future is unfolding photon by photon with each new photon electron coupling or dipole moment. The probability of quantum mechanics is the same probability we have with any future event represented mathematically by Heisenberg’s uncertainty principle ∆×∆p×≥h/4π.
By the way, being able to send a random message across a long distance to a receiver has great practical value in cryptography. The whole point of PKI is to securely transmit a private key, which is a shared random number. Also, if you ever remake the video, you might want to consider wearing a suite that has a large arrow pointing up on its front and back. That would make it easier to see if you are spin up or spin down. Great video. Excellent explanation for a strange and difficult topic.
I'm no theoretical physicist, but I believe I found an error in Veritasium's reasoning, and that the particles could indeed have all the information about their spins at their creation. Here goes: 6:15 The results being different for 5 out of 9 _combinations_ is NOT the same as the results being different 5/9 _times_. The explanation in the video is using the assumption that when an entangled pair of particles is created, the two "plans", plan 1 and plan 2 and all of its inversions, are randomly chosen from with equal weighting. I argue that it is quite possible for the resulting readings to differ exactly 50% of the time if the "plans" are chosen from according to a non-flat probability density function. Since the idea of these "plans" is a mathematical simplification of what would actually be going on in the particles (which don't care about our humanly invented 3-direction 60 degree measuring system), to assume a linear PDF for the plans is absurd anyway. So, I still suggest that all the information could be contained in the particles after their creation, and that they are not signaling each other faster than light. Is my reasoning sound? Prove me wrong!
The Bell inequalities actually make no assumptions about any plans. They're purely a consequence of measurement outcomes, and no plans are taken into account. If you know a bit of mathematics, then look up the CHSH inequality for which there are some simple explanations, including in Preskill's notes (one of the guys who is credited with helping Veritasium on this video). This inequality shows that in a system with two pairs of variables, each with binary outcomes, then certain correlations of those variables are impossible in any locally realistic framework, There are loopholes to the Bell inequalities, but they are usually of the type that require the universe to conspire against us.
Benjamin Hershey Your close. The probability matrix is not 3x3=9 combinations, it is 3! = (3 factorial)=3x2x1=6 combinations. So instead of 5/9 for the hidden variables it would be 3/6 for the hidden variable premise. This is actually a class of very common misconceptions in applying probability theory. it helps if you consider the total possibilities for picking the detectors in relationship to each other. In the diagram shown with 2 detectors having angles labeled 1, 2 and 3 each you want define your possible choices of random detectors as. 1) the same detector direction in both devices A and B (draw arrow going in to center and coming reversing direction) 2) a detector in device A and the next counterclockwise detector in B (draw arrow Going in to center and bending right) 3) a detector in device A and the next clockwise detector in B (draw arrow Going in to center and bending left) The problem comes from the assumption that the two experimenters are picking randomly from 3 directional detectors. But when you are computing probabilities you for a system of two experimenter then you need to recognize that it's the relative directions being measured. Another way of clarifying the false assumption leading to the 5/9th prediction is to recognize that if experimenter A picks a direction first it doesn't matter which direction A picks to the outcome. It matters only What direction experimenter B picks in relationship to Experimenter A. . . . this is wrong . . . A | B ------------------------ Direction 1 | Direction 1 Direction 1 | Direction 2 Direction 1 | Direction 3 Direction 2 | Direction 1 Direction 2 | Direction 2 Direction 2 | Direction 3 Direction 3 | Direction 1 Direction 3 | Direction 2 Direction 3 | Direction 3 . . . This is correct . . . A | B ------------------------------------------ Any Direction | Same direction as A Any Direction | Clockwise of A Any Direction | Counterclockwise of A
Steve Whetstone Thanks for that feedback. So are you saying that when the correct assumptions are applied they do not guarantee a >5/9 statistic? Or are you merely simplifying the problem and agreeing with the video? (I'm asking because I don't have time to fully think about what you said right now. I'll take a closer look later.)
Veritasium think i finally get what schrodinger meant by ''the cat is both dead and alive'', its just that there is no hidden info, or predefined state prior to opening the box, just as the electron pair contains no information prior to being measured!! Is that correct?
xoviat xo Well done! If you worked in some redundant systems to double check information I can see that being effective. 5 minutes is a long time to blink out binary or morse code, but the time scale is arbitrary. If it can be done, it can be done faster. You would of course have to keep very accurate account of time dilation and compensate measurement times accordingly.
xoviat xo When you measure the particle's spin, you break entanglement, because measuring the particle influences it. Only the first measurement counts, you can't just keep measuring till you get the result you want.
I'm unsure if this comment will ever be read, but I have a question. In the last part around 7:38 in the video, we have a 1/3 probability of the detector measuring the spin in direction 1, so we will have a probability to measure the particle in the downward direction as 1/3 since we know that in direction 1 the spin of the other particle is up spin (SO WE KNOW WE HAVE A 1/3rd chance of measuring the particle's spin as we know it to be). But, we also have a 2/3 probability of detector B choosing either direction 2 or 3. We know that the particle spin makes a 60-degree angle with directions 2 and 3 since we know it has a down spin in direction 1. So the particle will have a 3/4 probability to be spin up and 1/4 to be spin down. The total probability to measure a spin down would therefore be 1/2 (3/4*2/3) for the second particle. My first question or rather a critique is that the probability is incomplete (total is less than 1) if we combine the two scenarios i.e. spin of particle B (2nd particle) measured in direction 1, and directions 2 and 3 (1/3 + 1/2 is less than 1). So we're missing out on a scenario here that we can't account for, is my best guess. The reasoning behind my probability being 1 in total is the fact that by the law of conservation of momentum, we should observe the exact opposite spin of the particle A measured in that same direction. Secondly, even is this part is true, what is to stop particle A from changing its spin the moment we measure a different spin on particle 1? Essentially, probabilities are used to understand what will happen for a large number of particles, but what if the spins are hard-coded for the particles. If particle A has an up spin in direction 1, particle B will have a down spin in direction 2, but if particle B's spin measured in direction 2 or 3 is up not 3/4th of the time but for 3/4ths of the particles (if there were 4 particle pairs (8 in total)), then 3/4 particle A's will have a down spin in directions 2 and 3 respectively while the 4th particle A will have up-down-up?
i did a high school project about this exact thing last year, this video came to a better conclusion and was far more understandable than any of the reseach i did over a couple months. thanks for explaining the thing i was meant to explain myself some time ago, i finaly have at least some grasp of how this works now, because even after the project i was still completely clueless on the logic behind it all.
overlordoftech The computers do not change the spin but rely on a property of the spins having more than 2 options (up or down) due to quantum superposition which is a probability. I think you are confused between changing the spin and observing the spin...
Veritasium What if we built two processors, both with access to particles that are entangled. When one processor analyzes the spin of said particles, the other processor then also analyzes the spin of it's particles. In the case of each processor, the values may be random, but we know that they are opposite of the values in the other processor. If we give each processor a sub processor that reacts to the results of the entangled processor it's attached to, but which assigns arbitrary information to the given spins it receives and then runs functions based on what the 'opposite' spin is, couldn't you then interpret those values and do something with them? Like, for instance, display on a monitor exactly what is happening on the other machine's monitor, just by preconfiguring the processors to act in exactly opposite ways?
But what if our detectors are changing the particles and we are not measuring an inherent spin, but adding spin? What I'm asking is if this could be an artifact of our measuring techniques?
It's not probable that *the entanglement* is an artifact of the measuring technique, as the technique would always impart the opposite result to entangled particles, thus it should respond to the fact that both particles were created together (aka the entanglement very probably exists anyways).
Kanglar If it doesn't matter than what are we measuring? Emilio Kolomenski It could be interference from the apparatus used to measure the spin or outside interference leaking in. Dose this phenomenon present itself in other techniques, are there other techniques?
actually the schrodinger's cat is something similar with what I have thought when i was still in elementary school when I thought about God. On my way to school, there was a branch on the road which I should choose every morning. No matter what I chose, each led me to my school. Every morning I had to choose between keep going straight or turn right. At that time, I was told that God knows everything, every action, whatever I did he will know, whatever I choose, and even whatever will happen in the future. So when I arrived at this branch it occurred in my mind, "if I turn right, will God know that I will choose right? is this what he observe from heaven ? but what if I keep going straight, will he also know that I will choose straight instead of right?" But later, whenever I chose on my way to school, I didn't think about or from how God's view anymore. I only thought how the possibilities happen in the future. Later I concluded, that it is possible that me choosing right and straight is happening at the same time on the future, but whenever I choose or decide, the other possibility happen and the other action is cancelled. But in my imagination, I still think, there is possibilities that me choosing the other cancelled action is still happening in the other future. Seems like Schrodinger's cat right ? I was still in elementary school at that time so there was no thought to turn into a formula.
No, that Schrodinger cat is an imaginary experiment that went wrong and out of hand. It is safer if you ignore it. His point was to show how absurd Einstein's interpretation of quantum mechanics was.
Awesome video, but I got a few questions: How do we know how the two plans are distributed? In the experiment, we can't really tell which plan the particle obeys to until measurement. So let's assume the first plan occurred with probability a and the second with probability b, so a+b = 1. Now we solve the equation a+b*(5/9)=(1/2). All solutions of a and b give distributions of the plans that would result in a 50% chance to measure different spins for the particles... Second question: What exactly would it mean to measure two entangled particles in two different directions? Is the upwards spin result of the measurement measuring in direction 'up' the same as measuring 'up' sideways? What would we get if we measure the same particle in different directions? The background of this question is: is the measurement still entangled if we measure in two different directions?
As someone who has a background in Physics, I always went along with the accepted point that the randomness within a quantum entangled system prevents FTL communications. I recently read a book 'Cracking the Cosmic Code' which actually shows that the randomness is not a restriction at all. It now opens up the distinct possibilities of FTL communications.
I don't understand one thing. Quantum mechanics says that the particle can have two states at the same time until measured. How do we know it doesn't already have the predetermined state? I mean we can only learn it's state by measuring it. How do we know the states aren't predetermined?
So, for example, I observe a particle and it gives a certain state. Then, I stop observing that particular particle for a moment, and measure it again. Will it have the same state as previously measured or will the state change 50% percent of the time. I'm talking about the same particle measured more than once.
Veritasium Yeah, it seems that I just did not understand you right, Derek. "50% chance of them having the same spin, that's 25% up-up and 25% down-down" is correct. You said quickly about that, I did not catch. It's my fault.
No it's 50%. It's only 25% if you say that both will be spin up. This is because the first one measured does not matter. It can be either spin up, or spin down. The second particle then has a 50% chance of matching the first particle. First particle: 50% chance of up or down. Either one works, and it is a 100% chance of picking spin up or spin down. Second particle: 100% chance of selectingn spin up or spin down, but only 50% chance of selecting the what the first particle selected.
Hard to believe Bostrom's simulation argument is taken seriously. If valid, that is that the odds are overwhelmingly in favour of us being in a simulation given the premise that it is achievable (very questionable), then the same argument applies to the folks who simulated us, and to their simulators on to infinite regress.
![Blox Fruits Dragon Rework Update [Full Stream]](http://i.ytimg.com/vi/EqDAp8udhm0/mqdefault.jpg)
i am in a superposition of understanding this video and not understanding it at the same time...
I got collapsed at not understanding it 100% of the time
nvm i get it now
Hahaha
Angular momentum is always conserved in the universe. Fundamental particles have angular momentum. As far as we can tell Quantum mechanics is inherently probabilistic so when you measure the angular momentum of a fundamental particle the result is random. When these two meet it seems that for angular momentum to always be conserved in the universe when the angular momentum of a particle is found another particle must change to be opposite of what it is, other wise angular momentum would change ever so slightly, and this is what we do observe with particles that are Quantum entangled i.e. the pair that change to always be opposites
I just checked and your wave function of all possible states collapsed into a single state: you don't understand it.
I understood everything up to 00:01
👌
Lol
lmao
But I Also Understood from last 0:01 sec
Wow, Veritacium teaches so well you understood it by 00:01.
"To understand spin, imagine a ball which is spinning, except it's not spinning and it's not a ball."
It is a property of a particle. We do not observe it in our macro world, so we do not have a word for it. So they called it a spin because it was the most appropriate word they could think of. It is hard to explain something you cannot observe by your senses, only the experiments give you information about it.
It’s easier than you may think. Mathematically if particles would have initially coordinate their spins it would give different result as opposed to what happens in reality. Meaning, if you throw a tennis ball on the wall on 60 degrees and the pair of that ball must behave exactly opposite then it should be 60/90 times or 2/3 of the time. If they calculate several possibilities of it like if 75 degrees 75/90 vs 25/90 etc then they compare it with what really happens it gives different result. If expected opposite percentage of spin is not equal to actual percentage measured in different angles of measurement then particles don’t have predetermined coordination. The only argument against thus may be that our math is incorrect, meaning math or probability as we perceive is completely irrelevant in this case. And I think Einstein could argue his case too. If there’s no specific “one” in this case then how can we say what would we expect from particles in the first place if they talked with each other before measuring. One particle can be on different places at the same time. There’s no one and zero in quantum physics, there’s no math here so talking about probability makes no sense.
holy crap !
@@johnphantom Can you make some kind of video or picture explanation of that thing. I am quite intrigued but I don't think I understand it properly. A video or picture will definitely help! Thank you!
@@abdullamasud4278 I think the best way to visualise it would be to model the simple calculator in Minecraft. Unfortunately, I know nothing about that application. I am looking for someone to help me.
I just sat down, listen intently to the contents of this video, and suddenly 9 minutes have passed without me knowing it and the video ends. What a brilliant presentation.
I've watched this explained 50 times, 50 different ways, and I still only understand 50% of it.
And for some reason, it's still interesting.
Still sounds like a telemarketing video trying to sell you some useless product.
You understand it and not understand it at the same time
@@OvoJeGovno shrodinger's understanding
I have been trying to get a grasp on quantum entanglement for a while now, I still don't think I understand any of it.
@@OvoJeGovno thats cos there was one universe in which you understand it and another one where you dont :) you are just superimposed now ;-)
I remember watching this video when it was released as a first year uni student. Now I work with quantum entanglement on a daily basis and this video was one of the things that piqued my interest in this field
Quantum physics is the truth of universe and lie of human consciousness saying that it does not need any observer or audience it knows its nature and truth
Specially in quantum entanglement universe is constant it knows what is up or down so where ever the particles go their nature is pre determined its just us making it complicated by knowing it after so many years of evolution
That's awesome
Aye, good for you man. I remembered when I first saw this video I thought to myself how crazy it is that we were even able to test hidden variables vs. quantum stuff. It was so abstract, and yet the experiment basically settles it. Kind of awesome
@@GoodVibes-pj9wd ehm.... What?
The particles may not be actually spinning but my head certainly is.
Lol
Oooh Boy... It surely did....
If you said otherwise you'd probably be misunderstanding something :p
Another applicable principal to spooky would be "vibes". Ever "vibed" with someone or say the same thing at the same time? That's one other application to spooky.
So what's the use of "spin"?
I remember watching this video when it came out back when I had just finished primary school, I barely understood anything. Now rewatching it, as I'm in the midst of my Quantum Mechanics course in Uni, it's both nostalgic and satisfying finally being able to make sense of these concepts. Amazing video, thank you!
Awww~ I really really really admire QM students 🥰🤩 You're epic~
In 6 yrs you jumped from primary school to university like how?
@@PDBisht in Europe when we say primary school we often mean primary and middle school so from "i just finished primary school" I think he meant something like just beggining High School
And in my country high School is 3/4 Years so it is possible to get into University after 4/5 Years of finishing "primary school"
@@PDBisht at least thats what I've been taught and seen being used
@@itiso1123 ah! I see here primary usually means 1-5 years of school after doing your pre-school and then 5 years of middle school after that 2 years of high school then only you'll able to enroll in college/university..
He lost me when he said "They're not actually spinning of course, they just have angular momentum and direction".
Yeah. I needed further explanation on that one.
Still do.
@Smit Shilpatul
Point objects ? I thought electron radius is on the order of 10^-17 m and also there are no actual material points in physics ?
@@Hexanitrobenzene there are no points kn physics, but there are en quantum mechanics, they're called quarks
I think the difference can be described as the orbit of the earth around the sun and it’s daily revolution. Both are a type of spin; I think he means to say the spin of the particles is more like that of earth’s annual revolution
@Smit Shilpatul so they are like packets of angular momentum?
Heisenberg and Schrödinger get pulled over for speeding.
The cop asks Heisenberg "Do you know how fast you were going?"
Heisenberg replies, "No, but we know exactly where we are!"
The officer looks at him confused and says "you were going 108 miles per hour!"
Heisenberg throws his arms up and cries, "Great! Now we're lost!"
The officer looks over the car and asks Schrödinger if the two men have anything in the trunk.
"A cat," Schrödinger replies.
The cop opens the trunk and yells "Hey! This cat is dead."
Schrödinger angrily replies, "Well he is now."
HAhahaahha
Very clever QM joke.
@Brett Dawson Cop shoots the cat, Schrodinger sues the City for unlawful death and wins case. Cop becomes lunatic
@fly med I never heard it before! So I'm okay with it. Hey, how about people who were born after the 1960s? They shouldn't hear it because you already have?
And of course, the cop THEN says, "Well, you do have a SPARE cat in your trunk, don't you?"
In order to understand that we don't understand entanglement, we should first understand that we don't understand spin.
In order to understand, we must disunderstand.
@@stupidrainbo is this xavier angel renegade?
@@stupidrainbo But somehow, our disunderstandment must be entangled with a "clearly understood" state. Preferably a "charmed bottom" state. Heh.
@@Trollificusv2 Charmed bottom... heh
Understanding how much you don't understand is the first step in understanding.
It's very complicated but I find this fascinating. It's one of those educational video's that you need to watch a couple of times before you start to understand.
Im not understanding :(
for real, how a particle can "give spin up for every measurement direction" by definition.. it's doesn't make sense..
and then try to explain this to someone but fail
"In order to understand it we must first understand spin. All fundamental particles have a property called spin. No, they're not actually spinning." You lost me. (0:41)
I looked up angular momentum in Wikipedia, and it had an still image of a gyroscope, spinning.
I'm also a little confused about how they have an angular momentum without spinning... I thought you needed one to have the other
the problem is that the particle doesn't have a physical form, so it can't really spin, but it still have angular momentum.
They may not have spin, but they are charming.
Why not? The moon will have angular momentum because it revolves around the earth (even if it does not spin around its own axis)
Thank you to those trying to make sense of this! For clarification:
1. We know the entangled particles must have undefined spins before we measure them because if they didn't they would sometimes give the same spin when measured in a direction perpendicular to their well-defined spins (and they never do).
2. We know the entangled particles can't have hidden information all along about which spin they will give in different directions because if they did we would measure different results at the two detectors >5/9ths of the time and we don't - we only get different results 50% of the time.
3. We can't use this behaviour to communicate faster than light because we can only pick the direction to measure in, we can't force the spin to be up or down - and it will be random with 50/50 probability. When the two detectors pick the same direction to measure in the results at one detector will be random but the opposite random of those measured at the other detector, which is a bit spooky.
However we CAN use it to generate perfect infinite one-time pads. So from a cryptography standpoint it's useful.
What is Factor Relativ to Asymmetry unity??
As its a 50 50 percent chance we cant use the data of up or down but they still gets data so using time intervals we can. a 1 is two ups or downs with a gap after and a 0 is one up or down with a gap after therefore it doesnt matter if its up or down
Can anyone see any problems
isaac heaton It is true that random information is data, but the data in this case isn't originating on either side. We can't tell a particle to be measured a certain way. Even if we had an agreement on which way we should measure them (and in what order), there's no way to impact what the other side sees.
THIS video will REVOLUTIONIZE education!
the spooky thing is, you're using yourself as a particle
Fifi Phoebe That looks very weird
xD
Lol!! Good one
It's time to *s p o o k e*
His explanation of 9 years ago is among the best I've heard yet. Every time I think, now it's making sense, hidden variables just keep popping back into my thinking. The problem reminds me of trying to explain why a mirror reverses only in the left/right direction and not in the up/down direction.
It's confusing no matter how you spin it.
Appleholic1 lololol
xDD
Mind blown 💣
I'll give you one up.
I don't understand any of this, but since it's technically teaching me something, I don't feel bad about not starting my paper on Shakespeare.
+Polly The Parrot that's what I call productination!
+beefcake It's different because there is no way you can pre-assign the spin of each particle to get the experimental results for all possible orientations of your spin detector. If the detectors were always in the same direction you'd have a valid point. But they are not. When you "do the math" you end up with the Bell inequality. If the inequality is violated, hidden variables (the pre-assigning of the frequencies of all possible outcomes for all possible detector orientations) are ruled out. Experimentally it's violated, which means it's spooky. And QM correctly predicts the results.
+Polly The Parrot at least you are educating yourself about something that passes most people by without notice instead of learning about old texts that have no real need in today's modern times
Brunneis Ursus Hey, careful what you say about Shakespeare. I wouldn't say there's no need for his works in modern times. Most are antiquated and boring, but he's the father of entertainment. If you're going to study acting or playwriting, you need to understand the origins of the field (That apples to screenwriting, too).
***** there is a theory that Shakespeare didn't even write his own work, some believe that there was a group of writers that wrote "Shakespeare's" plays and then gave credit to him, look it up, im not making this up, i learned about this in my senior year in high school, he did't have any of his own work, after his death they searched his home and he didn't even have a library that he would have needed to have knowledge about the ancient world or other places around the world, he also never really spoke about his works and was vague about how he came to write them...it makes you think
This is the best explanation I've seen of Bell's theorem, excellent video
also minutephysics
can you help me to finding anything that connects me to the original RAIF technology. disease (metastatic cancer)
I've always struggled to understand the experiments you mentioned regarding measuring entangled particles, and I found your visual representations to be very helpful.
When the words "the opposite random" entered my brain, it exploded.
I have no idea what this guy is saying. This must be how my mom feels when I try to explain how her iPhone works.
Derek Dufon 😂
He is bad
D E D
Exactly, he contradicted himself at the end
🤣🤣🤣yar.
Particleman... Particleman... does whatever a particle can. Spins around...up or down. Gets entangled. Traverses town...
someone give this man a trophy
+Gabriel Oliveira HOW CAN YOU JUST ASSUME GENDER LIKE THAT
+Kyle Groh Feminist.
+Spassky - Agar.io How is that feminism?
you forgot so look ooooooooout he is particleman
This video is straight fuego 🔥. Veritasium always explains things so clearly and carefully. I'm so grateful for all these dope science educators on yt so I can keep learning even after graduating. Cheers!
"If you think you've understood quantum mechanics, then congratulations, you've not understood quantum mechanics"
- Richard Feynman
He doesn't give congratulation for not understanding something. Be precise when using quotes.
God, I love that guy.
hehe...is this statement real ?
@@ananyasrivastava5128 It goes like this. If you think you understand quantum mechanics you have not understood quantum mechanics. Quantum mechanics we can do but to understand its weird nature is not easy for our deterministic brain.
Yeah you just made your life more spooky.. like Sir Einstein.
I understood 50% of this, and didn't understand 100% of it, so now I too can claim I know a thing or two about quantum mechanics.
Cool! So how do you create an entangled pair?
+aqouby 42
Jos Geerink You get an A+
You could say that you have quantum knowledge and by measuring you are changing it, so no tests for you only A+.
Crazy llama RUclips comments on science videos are some of the most civilized. It makes you even regain hope for humanity
Best explanation I have seen so far without over simplifying it. Thank you.
Following his explaination I could communicate faster than the speed of light (What did I miss? Please explain because this genuinely bothers me)
- Person A gets 100 Particles with spin "up" and Person B gets the 100 entangled partners of those having spin "down".
- Person A and B are many Lightyears apart
- Person A and B have aggreed on measuring the particle's spin regularly at every odd and at every even second respectively (always in their spins current direction)
Sending the message:
- A can measure one time only the spin of their 100 particles perpendicular to the usual direction thus changing the direction of the 100 spins but also of the entangled ones.
- B doesn't know yet that A has measured perpendicular and does the measurement still in his assumed current spin direction. BUT now on avg. 50 spins which were originally "down" will have turned into "up"
- Thus B will know that A has measured perpendicular.
@@csabadunai3760 the problem is we can't make A spin "up", because it has also 50% chance of up or down, so we can't send message to B as we can't control the spin of A nor block particular spins of As. Hope you understood
@@amarnathka2905 he wont, he's just THAT stupid
Narwhal Tamer What's the point in being toxic and calling people stupid?
Agreed. I'm surprised at how many commenters didn't get it. It seems pretty straightforward: particle spin can be up or down, but without getting together to share notes you can't tell whether it's significant or not, so you can't use this for FTL communication. It just begs the question of what's really going on -- which is what good science does, because good science not only provides answers... it breeds more questions.
Watching this video after the Nobel for Physics got announced. Gives me a basic idea of Quantum entanglement.
Quantum mechanics is spooky and often feels like sci-fi. That's why it's so interesting.
That's why you have psi and phi.
@@dhruvinvekariya975 sci phi how did I never see that before :0+--
The most understandable video I've ever seen about Bell's Inequality. Which is quite a complicated thing. Well Done Derek !
I really wish there was a good video explanation of what a particle spin is....ive never understood it.
and no one really does... That's the problem. Particles have angular momentum and direction but they're not really spinning like a classical object.
Veritasium I don't suppose you could make a video explaining spin some time in the future - if its possible to explain it.
Mee It is a property of atomic objects which has no (known) equivalent at our "scale". I think calling it "spin" is also confusing because people immediately relate it to our idea of what spin means when it's something different.
TheShreester what do you mean by no known scale? If we can measure this property of "spin" surely its something that can be described in terms of what it is ..
I said "no known equivalent at our (macro) scale" because there isn't one. The idea that particles have spin is an analogy intended to help us visualise what is going on.
Thank You so much for the short but very clear explanation at the end about why faster than light communication is impossible using entanglement. I finally understand something I have been trying to understand for years.
The fact that there's a viable market for this video means I'm dumber than I'd hoped
nooo, maybe you just dont understand fully the market? :)
Why did you hope to be dumb at all, in the first place? ( being exact with the English language on, “I’m dumber than I’d hoped” means you had a hopeful thought on being dumb.lol).
@@mattstevens4192 it could mean that he had hoped to understand spin but doesn't so he is dumber than he hoped. if you understand spin, you're pretty smart.
yes
@@mattstevens4192 bc he's being modest by assuming he was dumb all the time, but not "that dumb" assuming that and making the conclusion about the market of this video actually makes him smarter than he thinks he is. It is the not-dumb actually smart person that maybe don't realize he's smart dilemma.
Sort of
you just wanted a excuse to wear the spandex
This comment made my day
😂... Or “Wear Spandex and Spin around “
LOL!
Man, I've laughed at every single comment so far
Now I just need a video explaining this video
I like the idea of living in a "probabilistic" universe that just gets concrete when things are measured. So, this entangled particles don't need to exchange any information. It's just the observer who, by measuring the spin of one of them, enters into a specific universe in which the other particle is (and always has been) consistent with the measured one.
Superposition baby
@@sambennett996 I googled what you said for clarification and kept finding results of "babies" and "gender" and "quantum physics"...then I realized "baby" wasn't part of the term. 🤭
@@sambennett996 pls check my comment on this video. thanks
This view isn't as feasible as living in an idealistic world, it's an odd suggestion in favor of materialism that in order to be possible there has to be multiple earths with every single different probability and combination existing on it. But there are billions of billions of humans, with trillions and trillions of cells, all of which go through this same process. Meaning their are billions times billions times billions times trillions of other earths, which is a much more convoluted answer than something that can simply just be explained by idealism which is that reality is a mental construct and doesn't exist independent of observation.
Easy just "enter into a different universe" which actually seems unlikely and a bit of a cop out
I thought I was the only one who had trouble following this...after reading the comments....*whew* I feel better
no, u r supposed to have no problem following and having problem following this at the same time.
Dummy....
Kidding just kidding
its because 90% of people are braindead or are not even trying
Try watching it a few times. And/or take notes. Maybe look up another individual's explanation of Bell's inequality. Some folk understand one teacher while another understand a different teacher coming at it from a different viewpoint.
Nothing exposes the inadequacies of the human mind like quantum mechanics.
add beyond. please
That is so vague and sophomoric.
@@hunterliu6620 I think he meant that the human mind cannot contemplate such phenomena.
I know, right? Even searching “spooky action for dummies” hasn’t helped me truly understand it.
Or spandex.
Watching at 75% speed is helpful
thanks
thats about the speed of light u talking about
9:14:00 i think this will help.
I watch at 1.75 😂😂 maybe that's why I don't understand some stuff
Deep Vibes yup, the video didn’t stop, it the line continued past the limit
I had studied physics and did not receive such a good explanation during studies. In particular the bell experiment and why there are hidden constants. In the video it is a bit fast (should watch 75% speed 2 times and pause and ponder) but still extremely good. It is not easy, but essential, and the explanation is to the point.
Let's say we send a spaceship a lightyear away. On board, there's one particle and we program the spaceship to measure the spin at a specific time. If the spin is up, it destroys itself, if the spin is down, it keeps on flying.
If we measure the spin of the other particle here on earth at the same time, we immediately know whether the spaceship just blew itself up or is still flying - hasn't then information been transmitted?
also a good idea for like instant morse code; and could also probably be used for teleportation of some sort maybe
A hare does not aim accurately as we say in Sweden. No information is carried faster than light, instead the information is carried within the spaceship so to say, more precisely the information how to act upon a certain spin. It is apparent if you think about a little bit closer, the ship could stop to function at any point in the journey and the self destruct could fail for any reason, then the information we have sent with the spaceship ceases to be relevant and no faster than light indication of this is possible. If this happens we can very well be reading a spin up, assuming the spaceship has auto destructed as planned but until some sort of light speed information like electromagnetic radiation reaches us that tells the real tail we are only guessing, we can't know.
You can think of it this way, if we are to go through a labyrinth both at the same time we can entangle our self by saying when given a choice I will always go left and you will always go right. As soon as we make our first decision we lose all knowledge of each other and needs to communicate somehow to know anything about each other. I can however with this information follow you and find your entire path but I need to get this information in real time.
No information was transmitted. You knew state of the other particle by measuring the entangled pair that's all.
You mean: you have assumed that the spaceship blew up based on some expected cause and effect however you couldn't testify in court with certainty that you are now down one spaceship.
The only way to know that it blew up would be to confirm it by observing the ship after the time X, which would again put you under the speed limit.
I feel like I need to watch this video 1000 times to understand it.
You're not the only one.
this guy doesen't explain...he just shows his "intellegence"
this guy is explaining this topic in simplest way possible . You can't expect to understand these stuff without any prior knowledge.
there is a 50/50 chance that you will watch it up and 50/50 chance you'll watch it down. and the results will be different 5/9 of the time and so the results are different only 50% at the time.
and you still won't
Now my head is spinning too!
spin is just a property your head has gained through the course of video, its not actually spinning, don't worry🤣🤣🤣🤣
That means there must be another head somewhere which is spinning in oppsite direction.
That's called a Quantum Headache
Mine's spinning the other way....
@@null-calx lol 🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣🤣
INCREDIBLE VIDEO!!!!!!! I knew this was not going to be easy to understand. So I cleared my mind, sat back relaxed, and gave all my brain to understand this and also watched it 3 times, and I am really happy to totally understand what all you said. For me, It was my first video about the Quantum entanglement and you did a perfect job in keeping me enthusiastic about this SPOOKY topic ;D
I totally agree with you man, I’ve watched it years ago and didn’t understand well but I came back more intelligent and now I totally was able to understand him, I had to pause and rewind so many times 😂
Bell's inequalities are brilliant and mindblowing, with implications that go deeper than most people realize. They tell us that either locality (things are only influenced by their immediate surroundings) is wrong, realism (the moon is there even when you're not looking at it) is wrong, or both. Their most important lesson is that the things you assume, the things which seem like common sense, must themselves be subject to question, because reality might not agree with your assumptions.
No, macroscopic objects like the moon interact gravitationally and electromagnetically with their surroundings and are thus always present whether anyone looks at them or not. "Not looking" means no interaction. Only quantum objects are small enough for that to happen.
***** Realism, to a physicist, means that the properties of a physical system are mind-independent. In most cases, I'd be with you 100% on not applying quantum phenomena to the macroscopic world. But realism isn't a concept from quantum mechanics, it's all over classical mechanics. And we can't say that little things don't exist until we measure them, but the big things composed of them do.
If we accept the mainstream interpretations of QM, like the Copenhagen interpretation, then anything not being measured isn't there, but instead has only a probability of being in any given state when we do decide to measure it. That's weird. But the universe doesn't care about what we're comfortable with.
Matthew Prorok
My point is that macroscopic objects are always being measured. For them not to be measured, you'd have to turn off the moon's gravity and make it not reflect any sunlight, and it would also not have to block cosmic rays etc. Macroscopic objects have too many effects on the environment to behave quantum mechanically.
***** Well, this gets to one of the more difficult points in quantum mechanics, what "measurement" means. That's what Schrödinger's cat is about (which seems relevant here, since it was in making this analogy that he coined the term "entaglement"). What you're doing here is asserting macroscopic realism, which is fine. You can do that; plenty of people do. But it's still an empirical claim that's subject to testing, and Bell's theorem suggests that it could be wrong. As do some experiments involving macroscopic quantum phenomena (i.e. lasers, superfluids, and supercondutivity).
I'm not saying that macroscopic realism is wrong. I don't know whether or not it's wrong; nobody does, which is why it's still a topic of research. I'm saying that we can't assume it's right. And if it is right, then Bell's inequalities tell us that locality must be wrong. (Or, alternately, that we have to sacrifice counterfactual definiteness, the ability to speak meaningfully about the results of experiments we haven't performed yet, as the many-worlds interpretation does.)
***** From the moment it pops into existence, a particle is affected by gravity from everything in the (at least visible) universe, and its tiny gravity would affect other nearby particles and bodies much sooner than the entanglement-breaking measurement takes place. So does gravity not count?
this is the first video that made me actually understand “spooky action at a distance” it didnt make as much sense before, thank you!
Its incredible, unknowable things like this that make it fascinating to be alive! It's like, you want more of it, can't handle the reality of what is already out there , yet you yearn for more! Thank you sincerely!
this is the first time ive been able to understand why this doesnt allow for faster than light communication, good job man!
This might just be the best video about entanglement on RUclips. Incredibly helpful. Thank you.
"No they're not actually spinning, but they do have angular momentum"
aaaaand I'm lost
it's fine lol apparently no one really knows what spin actually means
@@vanibandodkar31415 it basically means it has momentum, I think. It just doesn't orbit.
@@watertommyz I have problems imagining something that has angular momentum but it's not actually spinning
Maybe they're doing jazzhands
@@LuisSierra42 Generally angular momentum is calculated about a point in space. So, even a particle travelling with a constant velocity, let's say in a direction parallel to the x-axis, has angular momentum with respect to let's say the origin. What angular momentum means here though, is a mistery to me as well. I need to learn more...
How can I find Jesus in all of this? I'm confused...
Jesus: SpinUp, Satan: Spin Down. There. Yin & Yang....or, does that only create more questions such as religion is only the result of polarity between pairs of matching particle probabilities...the world may never know. :)
Why is Jesus UP and Satan DOWN?
+NYCBG Just kidding, dude. Relax.
ppsayl123 And you thought I was serious??! ROFL.
+NYCBG These days? Who the hell knows. Lol.
I was literally just watching Only Lovers Left Alive again yesterday and them talking about Entanglement Theory and Einstein’s Spooky Action at a Distance and was trying to look up information on it yesterday but every description I found went over my head.
In sweeps Veritasium to save the day once again!! Lol
You rule bro. Keep it up!!
Well of course! Wait, what the hell did you say?
The universe is indeed, a fidget spinner.
XxFoxMotoX3xX 😂😂 Real life understood
Haha maybe❤️😂
and ur comment is indeed trendilly stupid.
albert foxstein
And you are playing with your mind, right now, right? (Your Mom warned you not to do that!)
“If you can't explain it to a six year old, you don't understand it yourself.”
- Albert Einstein
If you can't explain it to a democrat, you do understand it well.
@@ChristmasEve777 Always a condescending republican in the comments... You should know that everyone is annoyed by people like you. You give republicans a bad name. Luckily my republican friends are not this way.
Please leave politics out of science
@@steffenjensen422 Always a boomer in the comments. you should know that everyone is annoyed by people like you. Luckiely I'm not a boomer, so I can actually make fun of you lmao.
Jokes aside, i hate people that get mad because someone made a silly joke.
@@heisenmountainb6854 I understand that me getting mad instantly is annoying itself.
But I think it's warranted, since this kind of "little joke" is exactly why many people in the US can't communicate normally over party boundaries anymore and you'll probably agree that this is a real problem.
After all, a country where one side will just always try to hinder the other won't progress a lot anymore and will grow weak.
Maybe you're right and I'm overreacting - but maybe this is why we can't have nice things.
Also I'd like to point to this: ruclips.net/video/V-1RhQ1uuQ4/видео.html
I'm more confused than I was before the presentation. There are so many counter-intuitive issues raised and so many statements that need explaining, rather than just having to be accepted as self evident.
Having watched many videos on quantum entanglement, I can say that the explanation of john bell's experiment doesn't get better than this.
That is disappointing. Because I didn't understand it.
@@tabby73 the general genius idea is that apparently, if the information for what spins particles must have in which directions is predetermined (or determined at birth) then whatever that rule is, no matter how complicated it is, it must yield some ratio results for all three directions.
For example, 50/50 at a given direction.
So the great idea is, no matter what the rule is, if any rule exists, then the experiment should not match what we really get , which is 50/50
Dude my head started spinning after 2 mins of watching spin ups and spin downs.
There is a third interpretation : when you get the results of the second experiment, you are still measuring a quantum system (whose proper description depends on your results). This interpretation preserves locality, but is observer dependent. It is called relational quantum mechanics.
u don't get many likes because normal people in the comment section cannot understand you, mate!
let me like now and understand later
Oh God, please stop; my brain is full! 🤯
Somce it would be relational it woild be aligned with many aspects of physics
pls check my comments on this video, i think there is relativity. thanks
The mainstream media seem to have an issue with Social Media. Watching YT has engaged me with science more than since school 40 years ago. Stuff like this video has re ignited my mind much more than hearing sound bite news bulletins of fear & misery on repeat every 15 minutes….
I just love this video, this and the pilot wave theory video of Veritasium are classic master pieces among educative physics videos in RUclips
Yeah
Yours and mine are positive comments but I also see many false and dumb comments from others.
May as well be in japanese.
垂直から60度のスピンを測定するとどうなりますか？
LOOOL
@@jvincent6548 三角法を使うだけです。
@@midhunrajr372 私は知っています - 私はTom Wrightに応答して「皮肉」を使っていました
@@jvincent6548 そして私はあなたに皮肉をされていました。
04:10 You know things get real when the music kicks in.
Song name?
so does a quantum particle spin vertically before we choose to measure it horizontally @1:07 ?? I thought in this analogy it wasn't spinning at all UNTIL we choose a measurement?
I am smarter now. Not sure how, but I am smarter.
Does that mean that someone else got dumber?
Lmao
😂😂😂
I just love your videos. You do an amazing job of taking complicated interesting concepts and breaking them down with words and visuals that allow for those of us without formal educations to understand science on a much deeper level than we ever could. I'm tempted to suggest a topic for a video, but you keep coming up with such great ones that I'd rather just be surprised by the awesomeness you'll come up with next. Thank you so much for your hard work!
Thanks for your kind words - I appreciate the support!
I agree. Understanding Bell's experiment was on my to do list. Check!
This is what the salesman told me when I asked him about what plan was best for me if i switched to O2 as my provider.
The best video so far in explaining quantum entanglement
This is by far the best explanation of Quantum Entanglement I've ever seen!
Too advanced for a 15 year old some one help explain?
It's cool, no one gets it.. ;)
I'm twice ur age and I don't get it either
We might have no clue but it sure is interesting tho
You can go checking EPR paradox or Nicolas Gisin's work (quantum teleportation ?) sorry I'm a french speaker so... I can't really explain anything (plus I'm only 18 x)) just ... go check
PS : EPR paradox IS what "Einstein proposed", but he wasn't alone thinking about quantum entanglement so it is proper to talk about Einstein-Podolsky-Rosen
Ok thanks
my dreams tonight will be of spinning men in jumpsuits.
Once again, you've explained it better than anyone 😁
Thanks 👍
So... Is that clear for everyone? Ok!
Moving on to alchemy...
Jada been doing some spooky action at a distance.
Lmfao
Indeed, the observer (Will) got spooked by how hard she was getting 'entangled' in the distance.
Am I getting dumber or was this WAY harder to grasp than any other Veritasium episode? The video ended a few seconds ago and I have no idea what I just watched.
Thumbs up either way for using your 2 million subscriber channel for something like this, rather than yelling over video games or whatever ;)
wooohooo! Yeah this one is way harder than most things I've attempted. I actually made the first version seven months ago but it was impossible to understand, even minutephysics thought so. So I remade it and tried to make it more understandable. It's definitely better than the original.
Veritasium It can't be easy to explain something no one really seems to have figured out yet ;)
Whenever I watch / read something related to quantum mechanics it always just comes across as people thinking out loud. How much of the things you've said here is fact / theory / hypothesis?
Veritasium I think this is the best explanation I've seen of Bell's inequalities ab initio. I work in quantum information though, so I'm coming from the perspective of someone who already knows the material (nevertheless, that means I've also seen a lot of attempted explanations, including some of my own).
racoiaws This is fact, experimentally verified time and time again. The mathematics of quantum physics is well established; the only part people have trouble with is breaking down concepts into everyday language. This should be no surprise, because quantum physics explores regimes which are very far from everyday. We shouldn't expect our spoken language to have the capacity to explain it adequately, nor necessarily for these things to be intuitively graspable.
Quantum physics is possibly our most successful physical theory and none of its predictions have ever been proven wrong in experiment (and believe me, they've been tested).
Bell's Inequality is one of the harder theorems to understand in QM and one which most students struggle. Derek was brave to even attempt an explanation without using any maths! Putting this stuff into layman's terms is difficult but he seems to enjoy the challenge!
My questions:
1. How can a particle not spin if it has angular momentum? Isn't angular moment the definition of spin?
2. The guy is spinning the same way every single time after he goes through the cardboard, how is the spin changing? The only thing changing here is his orientation.
3. According to your equation, the "spin" (orientation) should always be up in the vertical cardboard experiment, but you show that it can be down?
What? Right over my head lol
James pls xD
Found you in the wild
It's okay. It was over Einstein's too...
I don't get his obsession with adhering to outdated Einstein's research
Entanglement is a property of waves if you drop a pebble into a pond the ripples will expand out from their centre. They will have the same up or down movement as they expand out at the same moment in time, they are entangled or synchronized. Quantum entanglement can be explained if quantum mechanics represents the physics of ‘time’ as a physical process. In this theory the future is unfolding photon by photon with each new photon electron coupling or dipole moment. The probability of quantum mechanics is the same probability we have with any future event represented mathematically by Heisenberg’s uncertainty principle ∆×∆p×≥h/4π.
So what I gathered from this video is that quantum mechanics is really f**king confusing
***** And also pretty awesome ;)
***** YES xD
***** the more you think you know the less you actually know. thats the joke at my college and most likely others.
+Matt G
I recently learned that about relativity. I thought I had a pretty good grasp on it but upon further research I found I out was very wrong.
+Matt G More than 5/9 of the time, it is a sign of exponential increase in intelligence.
By the way, being able to send a random message across a long distance to a receiver has great practical value in cryptography. The whole point of PKI is to securely transmit a private key, which is a shared random number.
Also, if you ever remake the video, you might want to consider wearing a suite that has a large arrow pointing up on its front and back. That would make it easier to see if you are spin up or spin down.
Great video. Excellent explanation for a strange and difficult topic.
I'm no theoretical physicist, but I believe I found an error in Veritasium's reasoning, and that the particles could indeed have all the information about their spins at their creation. Here goes:
6:15 The results being different for 5 out of 9 _combinations_ is NOT the same as the results being different 5/9 _times_. The explanation in the video is using the assumption that when an entangled pair of particles is created, the two "plans", plan 1 and plan 2 and all of its inversions, are randomly chosen from with equal weighting. I argue that it is quite possible for the resulting readings to differ exactly 50% of the time if the "plans" are chosen from according to a non-flat probability density function. Since the idea of these "plans" is a mathematical simplification of what would actually be going on in the particles (which don't care about our humanly invented 3-direction 60 degree measuring system), to assume a linear PDF for the plans is absurd anyway.
So, I still suggest that all the information could be contained in the particles after their creation, and that they are not signaling each other faster than light. Is my reasoning sound? Prove me wrong!
There is no plan the particles could execute which would give
The Bell inequalities actually make no assumptions about any plans. They're purely a consequence of measurement outcomes, and no plans are taken into account. If you know a bit of mathematics, then look up the CHSH inequality for which there are some simple explanations, including in Preskill's notes (one of the guys who is credited with helping Veritasium on this video). This inequality shows that in a system with two pairs of variables, each with binary outcomes, then certain correlations of those variables are impossible in any locally realistic framework,
There are loopholes to the Bell inequalities, but they are usually of the type that require the universe to conspire against us.
Veritasium Thanks for the response. I did a bit more research into Bell's theorem and you are right. There's something else going on. QM is weird! :P
Benjamin Hershey
Your close. The probability matrix is not 3x3=9 combinations, it is 3! = (3 factorial)=3x2x1=6 combinations. So instead of 5/9 for the hidden variables it would be 3/6 for the hidden variable premise. This is actually a class of very common misconceptions in applying probability theory.
it helps if you consider the total possibilities for picking the detectors in relationship to each other. In the diagram shown with 2 detectors having angles labeled 1, 2 and 3 each you want define your possible choices of random detectors as.
1) the same detector direction in both devices A and B (draw arrow going in to center and coming reversing direction)
2) a detector in device A and the next counterclockwise detector in B (draw arrow Going in to center and bending right)
3) a detector in device A and the next clockwise detector in B (draw arrow Going in to center and bending left)
The problem comes from the assumption that the two experimenters are picking randomly from 3 directional detectors. But when you are computing probabilities you for a system of two experimenter then you need to recognize that it's the relative directions being measured.
Another way of clarifying the false assumption leading to the 5/9th prediction is to recognize that if experimenter A picks a direction first it doesn't matter which direction A picks to the outcome. It matters only What direction experimenter B picks in relationship to Experimenter A.
. . . this is wrong . . .
A | B
------------------------
Direction 1 | Direction 1
Direction 1 | Direction 2
Direction 1 | Direction 3
Direction 2 | Direction 1
Direction 2 | Direction 2
Direction 2 | Direction 3
Direction 3 | Direction 1
Direction 3 | Direction 2
Direction 3 | Direction 3
. . . This is correct . . .
A | B
------------------------------------------
Any Direction | Same direction as A
Any Direction | Clockwise of A
Any Direction | Counterclockwise of A
Steve Whetstone Thanks for that feedback. So are you saying that when the correct assumptions are applied they do not guarantee a >5/9 statistic? Or are you merely simplifying the problem and agreeing with the video? (I'm asking because I don't have time to fully think about what you said right now. I'll take a closer look later.)
Veritasium think i finally get what schrodinger meant by ''the cat is both dead and alive'', its just that there is no hidden info, or predefined state prior to opening the box, just as the electron pair contains no information prior to being measured!! Is that correct?
Exactly!
That means you are both human and non human. It depends on how you are measured.
xoviat xo Well done! If you worked in some redundant systems to double check information I can see that being effective. 5 minutes is a long time to blink out binary or morse code, but the time scale is arbitrary. If it can be done, it can be done faster. You would of course have to keep very accurate account of time dilation and compensate measurement times accordingly.
xoviat xo When you measure the particle's spin, you break entanglement, because measuring the particle influences it. Only the first measurement counts, you can't just keep measuring till you get the result you want.
Did you get dizzy?
_ Madcrafter _ yup
I did!
Yes
I'm unsure if this comment will ever be read, but I have a question. In the last part around 7:38 in the video, we have a 1/3 probability of the detector measuring the spin in direction 1, so we will have a probability to measure the particle in the downward direction as 1/3 since we know that in direction 1 the spin of the other particle is up spin (SO WE KNOW WE HAVE A 1/3rd chance of measuring the particle's spin as we know it to be). But, we also have a 2/3 probability of detector B choosing either direction 2 or 3. We know that the particle spin makes a 60-degree angle with directions 2 and 3 since we know it has a down spin in direction 1. So the particle will have a 3/4 probability to be spin up and 1/4 to be spin down. The total probability to measure a spin down would therefore be 1/2 (3/4*2/3) for the second particle. My first question or rather a critique is that the probability is incomplete (total is less than 1) if we combine the two scenarios i.e. spin of particle B (2nd particle) measured in direction 1, and directions 2 and 3 (1/3 + 1/2 is less than 1). So we're missing out on a scenario here that we can't account for, is my best guess. The reasoning behind my probability being 1 in total is the fact that by the law of conservation of momentum, we should observe the exact opposite spin of the particle A measured in that same direction. Secondly, even is this part is true, what is to stop particle A from changing its spin the moment we measure a different spin on particle 1? Essentially, probabilities are used to understand what will happen for a large number of particles, but what if the spins are hard-coded for the particles. If particle A has an up spin in direction 1, particle B will have a down spin in direction 2, but if particle B's spin measured in direction 2 or 3 is up not 3/4th of the time but for 3/4ths of the particles (if there were 4 particle pairs (8 in total)), then 3/4 particle A's will have a down spin in directions 2 and 3 respectively while the 4th particle A will have up-down-up?
Test it enough times and your result will be:
"Error x00042:
Universe.exe has crashed"
This comment should have a lot more thumb ups!
The best joke over here
LOL 😂😂😂😂😂😂😂
Are you implying that we are living in a simulation? 😂😂
@@HeavyYouTouber it s possible. Dont be troll
So, is the earth flat?
no
yes
in some places
in another universe
42
The particle planning to do a spin down - Why am I wrong? Why is there negative music for me?
i did a high school project about this exact thing last year, this video came to a better conclusion and was far more understandable than any of the reseach i did over a couple months. thanks for explaining the thing i was meant to explain myself some time ago, i finaly have at least some grasp of how this works now, because even after the project i was still completely clueless on the logic behind it all.
The thing to appreciate is that you tried
Einstein was a real OG, I can't wait for a Zweistein
Dreistein is the real pro
Underrated comment.
I personally stan for Siebenstein.
Who else is watching this at 4 AM, while procrastinating an essay due at 9 AM?
No, it's only 3am for me
srsly. its 4:20am
Just you buddy :)
4:55 am bud.
I have an exam due of simple mechanics and here i am watching a video on quantum mechanics.
Soo... we cant use this for faster than light communication because we cant change the spin?
correct
Veritasium ok :(
Veritasium But don't quantum computers work by changing the spin of electrons?
overlordoftech The computers do not change the spin but rely on a property of the spins having more than 2 options (up or down) due to quantum superposition which is a probability. I think you are confused between changing the spin and observing the spin...
Veritasium
What if we built two processors, both with access to particles that are entangled. When one processor analyzes the spin of said particles, the other processor then also analyzes the spin of it's particles. In the case of each processor, the values may be random, but we know that they are opposite of the values in the other processor. If we give each processor a sub processor that reacts to the results of the entangled processor it's attached to, but which assigns arbitrary information to the given spins it receives and then runs functions based on what the 'opposite' spin is, couldn't you then interpret those values and do something with them?
Like, for instance, display on a monitor exactly what is happening on the other machine's monitor, just by preconfiguring the processors to act in exactly opposite ways?
I think if you substitute the word synchronized for entanglement and the word possibility for superposition, it is much easier to understand.
I agree. Some time ago I took to calling them "synced particles."
I was thinking the same thing. The world "entanglement" is misleading.
@@SimplyBergman True, it makes it sound like it is a bunch of mixed-up iPhone chargers
But what if our detectors are changing the particles and we are not measuring an inherent spin, but adding spin? What I'm asking is if this could be an artifact of our measuring techniques?
Yeah same question here
*****
But are we sure that the technique isn't imparting somthing into the system?
Jeffery Liggett
It doesn't matter if it is or not. For reasons stated by the previous commenter.
It's not probable that *the entanglement* is an artifact of the measuring technique, as the technique would always impart the opposite result to entangled particles, thus it should respond to the fact that both particles were created together (aka the entanglement very probably exists anyways).
Kanglar
If it doesn't matter than what are we measuring?
Emilio Kolomenski
It could be interference from the apparatus used to measure the spin or outside interference leaking in.
Dose this phenomenon present itself in other techniques, are there other techniques?
actually the schrodinger's cat is something similar with what I have thought when i was still in elementary school when I thought about God.
On my way to school, there was a branch on the road which I should choose every morning. No matter what I chose, each led me to my school.
Every morning I had to choose between keep going straight or turn right.
At that time, I was told that God knows everything, every action, whatever I did he will know, whatever I choose, and even whatever will happen in the future.
So when I arrived at this branch it occurred in my mind, "if I turn right, will God know that I will choose right? is this what he observe from heaven ?
but what if I keep going straight, will he also know that I will choose straight instead of right?"
But later, whenever I chose on my way to school, I didn't think about or from how God's view anymore. I only thought how the possibilities happen in the future. Later I concluded, that it is possible that me choosing right and straight is happening at the same time on the future, but whenever I choose or decide, the other possibility happen and the other action is cancelled. But in my imagination, I still think, there is possibilities that me choosing the other cancelled action is still happening in the other future. Seems like Schrodinger's cat right ? I was still in elementary school at that time so there was no thought to turn into a formula.
sounds like u need an experiment
Marvellous thinking
Dude... this is how I live my life on a day-to-day basis. Wow.
No, that Schrodinger cat is an imaginary experiment that went wrong and out of hand. It is safer if you ignore it. His point was to show how absurd Einstein's interpretation of quantum mechanics was.
no. trust me you end up at the same school but the difference in path makes it, and everything different.
Awesome video, but I got a few questions:
How do we know how the two plans are distributed? In the experiment, we can't really tell which plan the particle obeys to until measurement. So let's assume the first plan occurred with probability a and the second with probability b, so a+b = 1. Now we solve the equation a+b*(5/9)=(1/2). All solutions of a and b give distributions of the plans that would result in a 50% chance to measure different spins for the particles...
Second question: What exactly would it mean to measure two entangled particles in two different directions? Is the upwards spin result of the measurement measuring in direction 'up' the same as measuring 'up' sideways? What would we get if we measure the same particle in different directions? The background of this question is: is the measurement still entangled if we measure in two different directions?
im really tired but im putting his comment here so I can read it and try to answer when im not
@@invisibilius1978 Have you already awaken from your slumbers?
@@piepo5002 yeah and I think I get it now though I can't answer because I'm not a quantum physicist. thanks for the reminder I forgot about this
As someone who has a background in Physics, I always went along with the accepted point that the randomness within a quantum entangled system prevents FTL communications. I recently read a book 'Cracking the Cosmic Code' which actually shows that the randomness is not a restriction at all. It now opens up the distinct possibilities of FTL communications.
I don't understand one thing. Quantum mechanics says that the particle can have two states at the same time until measured. How do we know it doesn't already have the predetermined state? I mean we can only learn it's state by measuring it. How do we know the states aren't predetermined?
Watch the whole video.
Did you watch the video? They aren't predetermined. They don't have a plan.
This is exactly what the video is all about. The 50% result can only occur if they aren't predetermined.
Its a little hard to wrap your head around but that is what he explains at about 4:15. (:
So, for example, I observe a particle and it gives a certain state. Then, I stop observing that particular particle for a moment, and measure it again. Will it have the same state as previously measured or will the state change 50% percent of the time. I'm talking about the same particle measured more than once.
This video made my head spin.
+Art Nymph Thanks for stealing my comment 1 month ahead of time... This was secret information.
+SturL Haha. It was all planned. ;)
@ Art Nymph: In which direction? LoL
spin up or spin down? :D
2:30 It's 25% that both particles will "spin up". Not 50%. (50% is for any of them. Not both.)
I said 50% chance of them having the same spin, that's 25% up-up and 25% down-down. But I like that you were thinking about it!
Veritasium Yeah, it seems that I just did not understand you right, Derek. "50% chance of them having the same spin, that's 25% up-up and 25% down-down" is correct. You said quickly about that, I did not catch. It's my fault.
No it's 50%. It's only 25% if you say that both will be spin up. This is because the first one measured does not matter. It can be either spin up, or spin down. The second particle then has a 50% chance of matching the first particle.
First particle: 50% chance of up or down. Either one works, and it is a 100% chance of picking spin up or spin down.
Second particle: 100% chance of selectingn spin up or spin down, but only 50% chance of selecting the what the first particle selected.
+DDogg43777 Derek has corrected me already.
+Alex Saver
Apologies. I missed the reply somehow.
If we're all indeed living in a simulation, programming quantum entanglement into our counterfeit universe was quite an impressive feat!
wow that's what I wonder as well.. if this is indeed a simulation... those guys up there are super smart beyond our imagination! (obviously)
Or it was a bug that the developers didn't fix because they didn't have sufficient headcount.
It ought to run with 640K for everything!!!
Hard to believe Bostrom's simulation argument is taken seriously. If valid, that is that the odds are overwhelmingly in favour of us being in a simulation given the premise that it is achievable (very questionable), then the same argument applies to the folks who simulated us, and to their simulators on to infinite regress.
@@lindakuttis Will you marry me, Linda Kuttis?
🧡