How Do Quantum States Manifest In The Classical World?

[@AlabasterJazz]

I like how you just casually throw in "yo, just in case you missed it, I just described how reality works" God I love this channel

[@ASLUHLUHC3]

Haha

[@libsteve]

I was having a hard time understanding the entangled consensus of relative position until you brought it back to the spin example, and then suddenly it made sense. The “consensus” is an internal logic. Entanglement preserves the logic of “this was spin up, so that must be spin down” because it’s a property of the interaction, not the particles. Even though the spin of the particles is uncertain, the interaction is defined, so the relation is agreed upon by all observers regardless the actual underlying state. This applies to relative location too. Two particles interact with each other across some distance, so that distance between the two can be known without needing to resolve the actual position of each particle. That “known distance” is spread across particles up to the macroscopic scale, preserving the logical property of the interaction without knowing the specifics. Since we too are a part of the entangled system of particles that is reality itself, we become a part of the entangled network of particles through which the logical consensus of an interaction in spread. Even if every particle of our own being is uncertain, the logical consequences of quantum interactions remain consistent, which is why we ultimately observe a single outcome-regardless the state, the consequences hold true, so the results always resolve relative to the observer’s truth. This is why entanglement doesn’t violate causality. Knowledge of quantum interactions is the real information-not the specific quantum states. This is really cool. It sort of reminds me of Wittgenstein’s “language games”, where the true meaning of a word doesn’t exist in the word itself, but between the speaker and listener as they communicate. The meaning of a word is created and agreed upon at the moment it’s conveyed from one person to the other, and exists only in the conversation between them.

[@airnidzo]

Are you telling me that we all percieve reality as we want to percieve it? Or atleast how we "think" we percieve it? So.. if things pan out scalably, my logic doesn't violate your. We will litterally change reality with the shere power of our will, given we all survive eachother and we level up our technological capacities.

[@libsteve]

Nikola Milovanovic not really. It’s more like the reality we already have is given a list of facts resulting from a quantum interaction that are then incorporated into itself. We don’t have control over the facts about that interaction, nor do we have control over the quantum state of our own reality. Our perception of reality is a product of reality itself, not the other way around, and so our perception remains consistent with our observations.

[@alexwood9941]

Elaborate on “Knowledge of quantum...” sentence, is this true that “information” in the quantum sense is defined by systems and relationships and not by individual states?

[@spider853]

so in other words multi worlds is like a stereo glasses filter, next we live in separate filters (or frequencies) that can't interact with eachother and sees different results (right/left eye) of the same mixed events (stereo movie screen).

[@YYYValentine]

This comment should be pinned on the top.

[@Ric-Phillips]

Experimental physicist, “That’s weird!” Theoretical physicist, “Here, I can fix that for you.” Experimental physicist, “What’s it gonna cost me?” Theoretical physicist, “Not much, just a few trillion new universes every pico-second.”

[@voidremoved]

Jesus: Hold my hand.

[@randomname2159]

@@voidremoved :))))))

[@ry517]

👌🏽😔

[@jerk1921]

No, not a few trillion. "Infinity"!

[@husnaink93]

These funny interpretations come when they try to minus God from the universe

[@GabrielVelasco]

Oh what an entangled web we weave, When first we practice to perceive

[@VibewithLeeLuu]

Gabriel Velasco clever and a good way to remember the concept

[@mamamheus7751]

Good one!

[@TehRedBlur]

I am in a superposition of confused and fascinated by the wonderful world of decoherence.

[@lenghi8048]

kushami

[@cristianm7097]

You barely cohere

[@neelroy2918]

Cant be. We observed you.

[@meestyouyouestme3753]

Does that mean you are in a superposition of being in a superposition and also not being in a superposition at the same time until you are measured? But if measured you wouldn’t be in a superposition so you can never be in a superposition?

[@Cliff86]

I like how quantum states becoming more and more entangled with their environments over time is somewhat analogous with the second law of thermodynamics

[@TN-mz5gw]

Quantum entropy!

[@TeodorAngelov]

Cutting edge gravity theories link it to entanglement(See Susskind on entanglement and gravity)

[@nucle4rpenguins534]

Von Neumann entropy

[@69karlprice]

ive almost solved it im nervous asf

[@monkieassasin]

This literally is the basis of thermodynamics. Thermodynamics is just an emergent phenomenon from quantum interactions.

[@donnierussellii4659]

My cat is so lazy I can't tell if he's alive or dead. Sometimes he gets entangled as well.

[@Invalid571]

Lol

[@mho...]

since cats are liquids, they just try their best not to evapurrate!

[@peikkojumala]

I feel like that so often, maybe I'm the one who is entangled with your cat :s

[@mikhailmikhailov8781]

Schrodinger had a lot of experience with cats, his Cat is a lab report, not a thought experiment.

[@nupaulmiller6412]

LOL

[@Deeplycloseted435]

Quantum biology is a thing now. An AMAZING thing. I wish it was a thing back when I was 19 and choosing between biology and physics. Quantum mechanics is occurring within us all, constantly, and everywhere in the biological world.

[@greedowins]

The implication that quantum effects only happen in cold/dry environments has been silly this whole time. Obviously they are easier to observe in very simple closed systems (cold, vacuum, tiny number of total particles, etc.), but I've heard really smart people talk about this stuff and they often mistake their observational limitations as the limit of physical interaction.

[@robert_costello]

I regret not going to school all the way. I am but a roofer. Studying quantum physics and medicine was my dream. Unfortunately, I couldn’t live out that dream. I’m so impressed by your intelligence, and a little envious... in a good way. Informally, KZbin has been my class. 😢 please don’t stop posting these great videos. I’ve learned so much, even though I will never use said information. I doesn’t hurt to pretend, every now and again. 🙂

[@DeElleOcala]

.

[@bruceh9780]

Even if you went to school the whole way, it's likely you'd have never covered this stuff unless you're in a very specific degree. You're about as capable as every other non-physicist/mathematician in understanding this kind of stuff :)

[@macysondheim]

Get back to work… before I call up your employer & share how you have been watching videos & leaving long comments instead of focusing on your job. Customers want things done in a timely matter, with quality. Not a poor job done by someone who’s distracted. This also raises safety concerns that I could report to OSHA. Get your @$$ back to work… Now.

[@robert_costello]

@@macysondheim Robert, the guy who made that comment killed himself 2 years ago.

[@DipsAndPushups]

Go study it now, it is not too late

[@tomaszwoszczynski9633]

Wojciech Żurek is my grandmother's cousin yet i have never had occasion to met him mostly due to fact that he live on other continent. Anyway i have alvays been huge fan of PBS and i'm thankful for your work to explain complexity of the universe as good as we know it to the simple audience. I wish you all the good luck.

[@burtosis]

How do they manifest? I simultaneously both understand and do not understand PBS space time episodes.

[@korpen2858]

Quantum superposition of understanding

[@heavenbot]

As short as I can understand it, the moment you measure something it becomes classical. When you measure, you unwittingly allow the rest of the universe to entangle itself with what you look at. The universe then selects a chosen state to be the one, or not if there's multiple universes endlessly splitting.

[@ilejovcevski79]

Based on this and the episode on decoherence, the way i see it is there are at least two levels of "reality", the "underlying" one, existing always in a state of superposition, lets call it a fundamental one, and he one on the "surface", or the way i like to call it, the "perceived" one. As Mat mentioned, if the probability wave function is the wave upon which we "surf", then the manifestation that we measure in our "classical" notion is a single point along the front. We certainly perceive (and measure) a state of that wave, but by no means is that state all the states in which that wave exists "at the same time". That's at the least the way i try to picture in inside my head. Or the closest i can and still drawing analogies based on "mundane physical" reality. I could be WAY wrong though.......

[@seriousthree6071]

It is simple, everything lies to you, but especially politicians. Do not expect your senses to tell you the truth and you will not go far wrong.

[@mattm8098]

@arvinash does a great job at explaining the same concepts in simple ways.

[@marcussmart3275]

I love this channel so much. It reminds me of a very intellectual class I was once in called seminar. It was open discussion about whatever the class was interested in talking about. Sometimes spurred by our teacher. Though he was more of a professor. Mr. Lynn you made a wonderful impression on me. I hope you are well wherever you are in this world.

[@benl8962]

Me: *thinking i am sort of following what hes saying* Him: "Ive now basically told you how the world works" Me: "Wait what?! What did i miss???"

[@juniorballs6025]

*nods head emphatically*

[@persianskeptic4814]

So that's how I've been watching a 19 minute video for 45 minutes.

[@michaelcharlesthearchangel]

You in an Alternate Universe: How does the classical world tixEnter the quantum portAls (0-point worm "wHoles") of Quantum States/Statements existing inBetwixt parallel realities & their timelines/timecables? W0rmholes in Hyperspace are accessed & chrono topologically Hamiltonian Stabilizer-enCoded. The framework of wormhole technology gives way to antigravity. A sustained wormhole that back into itself is at the heart of all UFOs & human-made Levitating Aerial Craft (LAC). Wormhole tech, using Earth as the Force Field ground for recurrent particle entanglement, has led to Timeline shifts. For example: Pittsburg in 1 Universe. :˙: Pittsburgh in One('s) Multiverse.

[@Vasharan]

Step 1: Quantum underwear. Step 2: ??? Step 3: Profit!

[@demandred1957]

@@persianskeptic4814 Yeah, I backed it up about 10 mins four times myself from that point..Still only get a vague sense of understanding..Or a feeling of that last gasp of air, when you are in over your head, and you cant swim...

[@tsmith906]

This is by far the most complicated in depth youtube physics channel ive ever seen. Bravo

[@lepidoptera9337]

Then you haven't seen much.

[@juzoli]

Okay, so measurement itself doesn’t exist, just an ever expanding network of wave functions. A measurement device is just a wave function added to the “original” wave function. The cat, and the human observer is also just another set of wave functions added to it.

[@Smerpyderp]

Right. So the act of “measuring” is really just the act of joining a wave function. That’s a neat way of looking at it!

[@juzoli]

@@Smerpyderp Well, “measuring” is just an interaction with a purpose. Interaction is just two particle colliding, which is basically the 2 wave functions of those particles adding up, creating new wave functions. Quite straightforward, if you think about it.

[@monkieassasin]

This is a good way of putting it. Now, keep that thought experiment going. What does this mean all the way up for the entire universe? Ask yourself, what are the philosophical implications of this?

[@Smerpyderp]

@@monkieassasin I’d say it means solipsism is more literal than I thought previously. It means that you are quite literally the center of the universe, and not just from your perspective, but even the laws of the universe seem to think so too. I’d have to give it more thought, but I think it has more questions than implications. I guess you could think of the universe as more like fractals of little smaller realities that interact with each other. I feel like there are many more ways to look at this. I’d be curious to know what you think. Maybe someone wiser than I could open me up to possibilities?

[@juzoli]

@@monkieassasin Not much. On macroscopic level, it doesn’t have much implications. You can approximate it very well using regular particle models.

[@Sam_on_YouTube]

When I wrote my undergrad thesis in philosophy of physics, I called the concept of the interconnected entangled wavefunction the "Universal Wavefunction." I don't remember where I got that term, but I'm pretty sure I did not coin it.

[@yuvalne]

Zurek looks like the physicist version of Bob Ross

[@siyacer]

*Leonardo DiCaprio

[@bartektrusewicz5718]

or rather his quantum entangled version

[@steve1978ger]

And here we have a little particle, but it needs a friend. Everybody needs a friend. So you can entangle it with anything you like.

[@Jondiceful]

That's exactly what I thought when I saw him too!

[@erictko85]

@@bartektrusewicz5718 😂😂😂 Thank you, you almost made me spit out my beer.

[@connerd5647]

my chin dropped off my face when that network of positions started lighting up, this is an insane framework and thank you for making it so conceptually accessible

[@rossk7927]

This feels like a computational power saving strategy where most of the time the question of "what is your spin?" is never asked so why bother always computing it. This is much like "lazy instantiation" in computer programming where you dont compute the answer until it is needed, but only ever compute it at most once. It seems as if the "answer" to "what is your spin?" is only calculated at the moment when the affect of that spin gains meaning or influence over some other physical system/interaction. Like if the snooping atom were to interact with another atom or field in some way where that "on vs off" state actually matters (e.g. is probed by a scientist) it is at that moment the entire state of the system becomes relevant and therefore the universe is forced to compute an answer to the previously unasked question. If we were in a simulation for example, this would come at the cost of increased memory usage in the tracking of the cascade of particles to be updated - or to have the ability to scrub the timeline back and forth a bit to recalculate things with new data. But hey, trading memory and compute back and forth is something we do all the time in software, is all that crazy that the universe might do the same? It sure sounds crazy to me (but so does quantum physics).

[@eh6968]

This was a beautiful analogy. Also means we have to liberate our minds, bust out the Matrix, and fight the machines...!!

[@1slotmech]

So we're living in a simulation where the timeline can be scrubbed back and forth somewhat at the smallest resolutions? 🤦🏾‍♂️🤷🏾‍♂️😏🤣🤣🤣 Interesting idea.

[@ebigunso]

You make it sound like Simulation Theory is real... And I can't deny it.

[@IqbalHamid]

OMG! Plausible and convincing argument in favour of the idea we are living in a simulation!!! Love it!

[@hansisbrucker813]

I thought about this as well 🤔

[@Plx499]

Matt, after viewing several clips on your channel, I really have to congratulate you to the comprehensive state-of-the-art information you provide there. Every student of physics should check out your channel which provides information crucial for understanding of a topic, but often not covered by university lectures (e.g. collapse of the wave function vs. decoherence).

[@cortezcabret9408]

This was the best episode I’ve seen. Incredible graphics. A very hard topic presented flawlessly. Well done!!

[@BillyViBritannia]

The way Matt pronounces names like "ultimate hair dryer" with a straight face always gets me...

[@3of19]

Fascinating episode. The whole quantum entanglement system reminds me of “Quantum Signatures” which on Star Trek are something used to check if you are in your own universe or have ended up in the Mirror Universe for example.

[@nemonomen3340]

A video explaining why we’re in the version of reality that we are is exactly what I’ve been waiting for.

[@jakefromstatefarm1405]

I just love hearing Matt say some ridiculous profile names at the end of each episode 😄

[@bobbyrobmaxey]

I love reading the comments for a video like this. A lot of smart, thoughtful people who are also interested in a subject that continuously blows my mind every time I watch a video or read about it

[@davidhand9721]

I really needed those specifics, dude. Without them, there's not a lot of meat on this one. I still feel like the measurement problem is hugely problematic, and I'll continue to have nightmares about it.

[@emrey.551]

Refer to the Stern-Gerlach experiment if you want some experimental observations for quantum spin. It provides a nice example that can help smooth out your understanding and also leads to some of the fundamental math (eigenvectors and such) that explain this problem.

[@michaelcharlesthearchangel]

I'll use Quantum Spin effects available to your human neurologicAl system & nerves to help you observe Quantum Spin happening between Parallel Universes (Timelines). But you have to Ask the Question differently, as a Quantum Question, to get a Quantum Answer. In Parallels: How does the classical world tixEnter the quantum portAls (0-point worm "wHoles") of Quantum States/Statements existing inBetwixt parallel realities & their timelines/timecables? W0rmholes in Hyperspace are accessed & chrono topologically Hamiltonian Stabilizer-enCoded. The framework of wormhole technology gives way to antigravity. A sustained wormhole that back into itself is at the heart of all UFOs & human-made Levitating Aerial Craft (LAC). Wormhole tech, using Earth as the Force Field ground for recurrent particle entanglement, has led to Timeline shifts. For example: Pittsburg in 1 Universe. :˙: Pittsburgh in One('s) Multiverse.

[@fqed]

The way I resolve this is that the superposition of any quantum system is irrelevant. On a macroscopic level, we observe the entire entanglement web. Similar to how we understand that an up spin can be defined as a super position of the left/right spin, our entire entagled web (macroscopic observer reality) can be defined as a superposition of the orthogonal orientation (wave function reality).

[@davidhand9721]

@@emrey.551 I am very familiar with that experiment. It's not an explanation of spin I need, but the details of how the atom became entangled without affecting the phase of the electron. It just seems like there's still a lot of magic thinking, only it's pushed down the road a little bit.

[@davidhand9721]

@@fqed I don't get exactly why the superpositions are culled as the web of entanglement grows. Why shouldn't it continue in its superposition?

[@cmilkau]

Again, spacetime raises the bar for accuracy per accessibility by an order of magnitude. Never stop pushing, we're loving it!

[@illesizs]

So, I'm left with a few questions after this episode: If quantum decoherence never actually happens, things just propagate out through the entanglement network, what would happen, when inevitably two particles interacted with eachother a second time? Would they re-entangle? Would that second entanglement overwrite their previous superposition, or would it just alter their state, keeping the information and adding to it? Is it somehow possible to measure their state from the first entanglement after their second encounter?

[@hafizajiaziz8773]

I would assume this is what you're asking: Two particle are entangled and they states are in superposition. After the measurement we thus destroy the superposition and entanglement. The question is, what happened if the two particle is "re-entangled" ? Well, simple answer is it would become a new entanglement. If the states of the two particle is in a superposition, it would be a new one.

[@calebmauer1751]

I think it's just entanglements layered on top of entanglements. The universe has a lot of memory and processing power.

[@NajwaLaylah]

@@hafizajiaziz8773 Like a man not being able to step twice into the same river, "because the second time it's not the same river and it's not the same man"?

[@hafizajiaziz8773]

@@NajwaLaylah exactly

[@hafizajiaziz8773]

@@sIXXIsDesigns maybe. But I'm in Copenhagen camp. Perhaps I'm wrong in my understanding.

[@brunoborma]

This was the most beautiful way I've ever seen of expressing information reading between quantum and macroscopic levels. A step further would be using that context to investigate the famous inquiry: "A tree falls in the forest. Does it make a sound ?"

[@NewMessage]

I have a hard enough time sorting out entangled power cords.

[@phoule76]

Merry Christmas

[@macronencer]

Probably the best video covering this topic that I've seen. I feel I'm grasping the concepts now. Even if I understood nothing, it would be worth sitting through the entire twenty minutes just for the now-traditional closing quip :)

[@Ole_Rasmussen]

I keep being able to hear when he's winding up to saying "spacetime" at the end.

[@voidremoved]

that faint ticking noise from the monkey on his back turning the crank...

[@gabor6259]

In this episode I totally didn't see it coming.

[@RaindropWorkshop]

The only part of this episode I understood

[@danieljensen2626]

@@gabor6259 You can always tell when he starts a long sentence using a lot of the key words from the episode and it isn't clear where he's going with it.

[@joshuadeyoung5540]

This version of you can. but what does that say about other coherent versions are they more or less likely to have the same ability

[@SLAMSTERDAMN]

Absolutely one of the BEST S.T. presentations ever. And THX for the intro joke, Matt, I really needed that.👍

[@fritt_wastaken]

Thanks, that cleared up some things. You know, that "how reality works" stuff

[@calebmauer1751]

Can't wait to apply this to my day to day decision making.

[@MrRogerb423]

@@calebmauer1751 how?

[@imad_uddin]

Such an amazing explanation of an extremely complex topic.

[@TS1336]

Hi there, greetings from quarantined Italy where, by the way, we are also experiencing an earthquake swarm.

[@ljuan5000]

America is is #1 at everything, ugh🙄 ... We'll see ur 20k and raise u 1 million.. poker terminology... in all seriousness, hope u guys are well

[@harikishore2514]

Get well soon Italy.

[@Trozomuro]

Hi there, greetings from quarantined Spain.

[@TS1336]

@@Trozomuro hola amigos, I see that you've joined us. Let's keep our fingers crossed.

[@emilioar7337]

@@TS1336 But not each other fingers... that'd be counterproductive Edit: typo

[@zackarytherrien]

I love how this video made me so confused, but instantly new ideas were forming in my brain. ❤️

[@ASLUHLUHC3]

[According to the framework of decoherence and these propagating pointer states...] "The observable qualities of reality - object positions, feline mortality statuses, even the results of quantum measurements - do *not* exist in the underlying quantum objects. Quantum objects remain in undefined and superposed states with no prefered basis for observation. No, the macroscopic observables only exist as a sort of mutual agreement across the network of entanglements that connect those quantum systems. In a sense, *we* exist in such a network." Also, my life is now complete: 16:30

[@GarrettRodgers]

What a slay at the end. Thank you for pointing out the biggest flaw with true immortality; what will you do when even the black holes irradiate out of existence?

[@badlydrawnturtle8484]

I have two marbles, one red, and one blue. I show them to you, and then put them in opaque cup and shake them around. Without looking, I have you grab one of the marbles and hold it in your hand without either of us looking. I then grab the other marble in a similar manner. Still holding our marbles without looking, we each get on a spaceship and blast off in opposite directions. After a few years of travel, I finally force open my cramped hand and look at my marble... and instantly know the color of your marble, even though you're several light-hours away. You can do the same, instantly knowing the color of my marble by looking at yours. We don't claim that the marbles are "entangled" and information has traveled faster than light. So... why do we claim that when talking about individual particles and spin?

[@badlydrawnturtle8484]

@@thijs2906 "Because that is assuming that both particles are different from the beginning, which they are not." I understand that this is the assertion being made, but it is a nonsensical one. You are claiming that something behaves differently when we aren't measuring it, which is both untestable by definition and in violation of Occam's Razor. "In your case, assume that the 2 marbles each have a 1/2 probability of being either blue or red." Which, from my perspective, is exactly what happens with actual marbles in an actual cup: I don't know which one I grabbed, so I must assume a 1/2 probability each of it being blue or red. "The moment I or you grab a marble from the opaque cup, and measure it's color, the other one instantly assumes the other color," I can't tell if you're honestly arguing that the state of marble in my closed hand changes color when you look at your marble, or if you just don't understand the hypothetical. From your perspective of probability, yes, you can know from the moment you check your marble that the marble I took is the other color. You can be sure that when I look, if I do, I will find it to be the color that your marble is not. But your observation has not ACTUALLY changed anything. From a global perspective, the universe has already decided which marble I had the moment I grabbed it; the change in probability when you measure your marble is only a matter of knowledge based on your perspective, not a literal change in actual properties of any objects. Again: Why should we take this untestable, unnecessarily complicated position that the particles are different while they're not being observed? It would appear to violate multiple basic tenants of logical reasoning, and you've just repeated the assertion without justifying anything.

[@badlydrawnturtle8484]

​ @Thizzeh "I'm not claiming that something behaves differently when we are not measuring it - I'm just saying what quantum mechanics tells us, which is that before observing a particle, it exists in a wave of probability," No. This is flat false, as you would understand if you actually paid attention to the very videos this conversation is happening under. Quantum mechanics does NOT claim that the particle actually exists as a wave of probability, any more than probability theory tells us that the marble in my closed hand is a wave of probability until I open my hand and look at it. "It has however, been proven countless times, over and over, working out all the loopholes that 2 entangled particles, split from an original, will always assume opposite properties when either is measured, independent of location in spacetime." Which is PRECISELY the behavior you would expect if you assume that the particles have already taken those properties before they are measured, as the marbles already have definite, yet unknown, colors. "If you're questioning why something so absurd and counterintuitive is happening, then you must understand that the universe and its workings have no obligation to make sense to you." That is not remotely at issue, here. Go ahead and point to the part where I argued that it's wrong because it's counterintuitive or absurd... I didn't. I argued by use of analogy and reference to accepted rational principles. "Occam's razor tells us that we should not theorize or try to explain things that can not be empirically proven or need too many assumptions to make it work, because that would be unnecessary." ...Rational principles which you apparently don't understand. The words in that definition are somewhat correct, but they're jumbled up and combine to the wrong compound idea. Occam's Razor is the principle that we should attempt to minimize the number and scope of our assumptions. In this case, "the equations of quantum theory tell us what we're likely to measure at a given time and place" is a simpler assumption than "the equations of quantum theory tell us what we're likely to measure at a given time and place, and ALSO particles behave in a different way when we aren't looking (proposing an extra behavior unnecessary behavior for particles) and ALSO if this unobservable behavior is a thing we have to account for the instantaneous transfer of information (a significant complication that requires yet more assumptions to make sense of). "However, countless experiments have empirically proven that entangled particles, in fact, do behave in a way that is explained in the video." Again, this is impossible, because the claimed behavior is something that supposedly only happens when we aren't looking. The actual observed behavior is explainable WITHOUT the additional assumption of this unique, unobservable state.

[@badlydrawnturtle8484]

@@thijs2906 You have an incomplete understanding of the argument at hand. You, first off, continue to assert something while simultaneously admitting that the thing you are asserting is unknowable, and secondly, overstate the position of your interpretation in modern scientific discourse; polls of actual particle physicists have found that the interpretation you claim to be the consensus is a plurality position at best, not a majority (as in, more like 30-40% than the 95% you would need to reasonably claim consensus), and that most particle physicists don't even know the details of the argument and just kind of take it for granted.

[@aaardvaaark]

This ties in well with Veritasium's latest video on schrodinger's cat - he proposes that we consider "observing" something to be "entangling" with it, since the cat is attached to the box, the box is attached to the outside, and your eyes are attached (through photons) to the box. I guess another way of saying it is that entangled photons are only considered to be so because they've observed one another but nothing else has observed them yet.

[@fatmn]

14:38 "[...]boring old spacetime." How dare you.

[@csehszlovakze]

Greta?!

[@Stargaze_youtube]

Love space content, it motivates me to do videos about it ! ^^

[@moofree]

16:50 When PBS Space Time videos keep reminding you of the end of Outer Wilds, and you wonder when it will launch on Steam- so other people can experience the best game of 2019.

[@interdictr3657]

Thanks for reminding me of that game!

[@sundayridetexas416]

Sat here for 5 minutes typing, deleting and retyping, deleting comment to try to ask a question, but I wasn't able to formulate my question into words. So I am writing this comment. Hopefully yall will answer the question in a future episode or I will figure out a way to ask my question. Mind bending thought series yall have currently.

[@NIXNYKYO]

How is the entanglement broken so? When the electron enters the magnetic field, doesn't it interact with a bath of photons (those which make up the magnetic field)? Are those entangled as well with the positron?

[@fatmn]

I have to imagine everything is entangled with everything else. Perhaps that's what the universe is - a distinct set of quantum objects entangled together

[@seanriopel3132]

I like People who try learn how the universe works. It means something special when you can hold intelligent discussions and exchange ideas

[@WickedTerribleTheatr]

This all has got me thinking: if many worlds is true, there are "universes" out there that always measure nothing of value in the double slit experiment, and thus cannot explore quantum physics. Perhaps we're in a universe where our results will come "just so" at some point and we'll never get to unlock some future level of understanding. Depressing.

[@dustinjenkins8215]

This is my personal problem with the many worlds, essentially that has to mean there are infinite worlds. There are worlds where you suddenly and spontaneously turned into a cat or worlds where Chuck Norris isn't...this doesn't seem possible, or testable.

[@tanta1519]

@@dustinjenkins8215 That's a misconception of the many worlds hypothesis. Every "world" follows the laws of physics, only the things that could happen can happen, so there wouldn't be a world where you spontaneously turn into a cat. There certainly could be a branch where Chuck Norris doesn't exist though. Sean Carrol is pretty interesting to listen to on this subject, he was on Lex Fridman's podcast, and he talks about precisely these things, as well as testability. Also It's not necessarily infinite, it could just be really large, but finite, that's not something we know.

[@dustinjenkins8215]

@@tanta1519 So why couldn't, say, all of the carbon atoms in my body suddenly turn into nitrogen if a proton quantum tunneled into each of my carbon atoms all at the same time?

[@tanta1519]

@@dustinjenkins8215 that's another question entirely. I'm not a physicist, I'm certainly not an expert on QM, nor am I even necessarily a proponent of the many worlds interpretation(it's just an interesting hypothesis, that lines up with the math). I don't know whether what you described is physically possible, so all I can say is if it is, then there's an incredibly remote chance that that happens, if it's not then it can't.

[@dustinjenkins8215]

@@tanta1519 my point is, in many worlds, it certainly has happened.

[@ThanosDidTheRightThing]

Amazing video and science 🧪 content! I remember the day this video dropped! Times flies!

[@ilmbrk6570]

Another funny thought along the lines of that one "is there a timeline where entropy reverses" comment: Quantum mechanics is entireley probabalistic. If many worlds it true then there is a Universe in which physisists got completley bamboozled by quantum mechanincs and the double slit experiment never revealed the interferance patterns. Or even funnier, there would be universes in which the double slit experiment suddenly starts working or stops working. Imagine the confused look on the faces of those poor experimentalists!

[@jensphiliphohmann1876]

This might be true within another type of multiverse, and it's not sure that physicists can even exist within a really classical world (without quantum mechanics, chemistry doesn't work the same as it does in our universe). The quantum type manyworlds is not about many kinds of laws of physics but many possible outcomes within the known set of laws of physics.

[@ilmbrk6570]

@@jensphiliphohmann1876 But I am not talking about different laws of physics. I am thinking about one wehre all observable quantum mechanical effects due to chance seem classical. Imagine the double slit experiment yielding just two stripes on the detector screen due to chance.

[@morras87]

@@ilmbrk6570 Multiverse with Many worlds... interesting.

[@44264]

This video fix my insomnia. Thank you, PBS!

[@ZoldenGames]

So, there's a system of entangled particles, and they interact with each other, and their interaction makes impossible some possibilities to the point where only one combination of all possible superpositioned states of each particle make sense? Can we devise a thought experiment where a superposition of three particles create a system where some combinations of states contradict to each other, so the system is not measured from outside but we know its state? For example particle A is entangled with B, then A interacts and entangles with C, then B interacts with C in a way, that actually logically defines A, B and C while they all still are in a superposition of all possible states, just some of the states can' not be found on measurement.

[@amoses7178]

Well there wouldn't be any contradictory states... if I understand correctly, before measurement, C would be in a state that would reflect the possibility of A's state and B's state (that is it either agrees with A's state or B's state). This sounds a lot like one of those arguments that were being thrown around at the begining of the theory... cheats to learn 2 types of values at once (like both position and momentum at the same time). However in all these cases, when one parameter is adopted, the other becomes less accurate or even random. When you finally measure C to get the results, you'd get the effect of A or the effect of B but they would not disagree with one another on any contradicting state. Any system that requires a contradicting state to pick one result would exclude the other, even if the mesurement is after the fact. Try looking at Delayed Choice Quantum Eraser to blow your mind on that one.

[@craigcollings5568]

If I understand your question correctly, I think the answer from this video is that you _cannot_ know the state of a quantum system without becoming entangled with it. Where entangled simply means that the observer and the observed have become a single quantum system with their respective states superposed.

[@katphisH11]

This is exactly something I wanted to know about a couple days ago and I just find a video about it thanks

[@papinkelman7695]

18:08 ... I think I saw an attack ship on fire over the shoulder of orion, over the shoulder of Matt.

[@314159someguy]

This video was an epiphany moment for me. Thank you.

[@DarthMcLeod]

So do wave functions ever actually ever collapse? Do they simply interfere until there's a single or few physical results a la the distribution of photons in a double-slit experiment?

[@michaelelbert5798]

Wow ! Matt you got pretty close to actually deciding which one you believe. Good for you 👍👌

[@ILSCDF]

"I hope you enjoy watching the heat death of the universe"

[@soulmas520]

I've never felt so uninformed I've never had 20 minutes pass so quickly It would appear you're still on the ball Thank the crap out of you Sir O'Dowd of Matt (or IS HE??!)

[@persianskeptic4814]

When we say " observation " in all of these quantum physics scenarios, do we mean like actually observing with our eyes? Or our existence in the universe and experiencing it itself, is the observation?

[@TheZenytram]

A cable with a pointer going up or down, didn't you watch the video hehe

[@liggerstuxin1]

When we say we make an observation that means we made a measurement.

[@davidhand9721]

what you just asked is actually the point of this video and several previous videos. "What is measurement?" has no universally agreed upon answer. That's the measurement problem.

[@persianskeptic4814]

@@liggerstuxin1 I guess my question is more general. About all of the particles around us, we're seeing all of them in one position, the world is not a cloud of quantum superpositions when we close our eyes right? My question is, is us experiencing the universe, the measurement itself? Sorry in advance if my question sounds stupid.

[@emrey.551]

In the most essential sense, when we observe some phenomenon, we are collapsing the wave function into a single eigenstate (farside.ph.utexas.edu/teaching/qmech/Quantum/node40.html). This is caused by an interaction between the quantum mechanical phenomena and the external world (Us in this case). Note that the wave function itself is a superposition of multiple eigenstates (Eigenstates here are analogous to quantum spin, which can be represented as matrices) so one observation can have multiple possible outcomes (Again relating to quantum spin, up or down, left or right). Talking in more vague terms, the particle can potentially exist in multiple states, which we do not know beforehand; when we observe it we no longer are in the unknown and since we know that it can exist only in a singular state, it must and thus those appear as one of these potential outcomes. For the observation itself per se, that would mean either direct observation (Magnified reflection of light off of the particle and into our eyes) or some other measurement such as electron microscopes.

[@TehJumpingJawa]

A quantum web of trust. The parallels to computing are eerie.

[@xspotbox4400]

Dirk Gently's Holistic Detective Agency; Everything is connected.

[@nuggetdoozy7831]

I can watch these videos over and over and over again. I wonder if it’s better to watch many videos all day, never watching the same one twice. OR is it better to watch a few videos and repeat them all day. What’s best for the brain?

[@Zuuby]

Quantum particles have a much more exciting social life than I'll ever have.

[@fredjklein]

This truly puts a new spin on the topic.

[@ucrohenry]

Now my head is spinning both left and right. It's quite confusing.......

[@54m0h7]

I think that the solution to many of our current problems may be in thinking of fundamental particles are objects that extend into additional spacial dimensions. In these additional dimensions they interact and the result cascades into the effects that we see. For example: Say an Electron is a X=1,Y=1,Z=1, A=1, and a Photon at X=1, Y=1, Z=10, A=2. Their proximity in the A dimension creates their entanglement, which remains regardless of how far apart they are in the Z dimension.

[@anthonydunn729]

Honestly I feel like they're starting to go through science like a bonfire goes through wood. They don't bother to make things clear before moving on to the next concept, I'm not sure a single person I know would watch this episode, let alone walk away understanding much. Decoherence is a valuable concept, but there's already a video on that. For instance, it would have been cool to have had an explanation as to what can attract a spin up electron instead of a spin down electron. I thought they were guided by the 4 forces, of which gravity's negligible, strong and weak nuclear forces are irrelevant, and electromagnetism dominates. What could possible repel a spin down electron yet attract a spin up electron. And yes I can go google that, but I honestly believe it would increase the quality of these videos if you prioritized establishing context before moving on to the next idea. Also at one point he used spin and angular momentum interchangeably. But spin has more to do with how many times you have to rotate a particle in order to see the same thing. Spin 1 means you have to rotate it 360 degrees, whereas spin 2 objects only take 180 degrees of rotation. It feels like it's not even important if people can understand what you're saying. I as you start diving deeper I wish you'd start using a sample group of laypeople to test illustrations and explanations on individually, before stringing them all together into. Like, make sure they can accurately explain it to someone else, people are dumb and will usually claim they got it. Test them. There is real purpose in communicating science successfully. The more people can see the world in terms of science, the less vulnerable they'll be to viral forms of mental illness such as conspiracy theories.

[@calebmauer1751]

You can only spoon feed people so much, at some point they have to learn to take responsibility for their own learning. As a participant in the Internet though, I do realize this may be asking too much of people.

[@flameendcyborgguy883]

Well... My friend, we are tuching here the fabric of the uniwerse itself. It won't be clear, no, it will be more and more abstract. However I understand your anger and overall arguments. Fizic got beyond magic at this point.

[@anthonydunn729]

@@flameendcyborgguy883 that's a cop out. If it's been proven scientifically, then there ought to be a way to explain it clearly. Vonnegut himself wrote that any scientist who can't explain their work to a child is a charlatan. And I maintain that a test group for their material will be essential as the subject matter grows in complexity.

[@flameendcyborgguy883]

@@anthonydunn729 So for example explain me clearly what is Gravity, such that outside knowlege is not needed.

[@50ksubscriberschillinghomie]

This, needs to go viral

[@loonatic7]

Awesome video! I don't understand it at all but I feel smarter by just watching.

[@rishabh6374]

According to many worlds interpretation, my crush finally said yes to me in some other branch of reality😎

[@firebladetenn6633]

Rishabh and you win the Lottery every time you play.

[@ljuan5000]

She said no in many different ways. Sorry buddy! 😣😣

[@whiderboss]

in some other world I died by eating raw chicken while sleep walking but then I came back to life for no reason

[@DimitarStanev]

Actually quantum mechanics forbids this

[@Warguard9]

Give a thanks to Hugh Everett when meet him in that other reality!

[@S4LtyTrIcKs]

Fantastic episode, im reading Sean Carrolls book now and this is the perfect compliment

[@owensthethird]

All of my particles agree that I'm pretty awesome

[@interdictr3657]

nice

[@BarryKort]

At 3 minutes into the video, the spin axis is depicted as pointing in some fixed direction in space. But we could also model the spin axis as rapidly precessing around that presumptive fixed direction. If we adopt a model where the precession angle is 45° from the presumptive fixed direction, then that explains why a measurement in some arbitrary direction can appear to be random. If you apply the 45° precession model to a pair of entangled particles, then they jointly sweep out the surface of a double-ended 45° cone. As long as they remain perfectly coherent, one can draw a single line rotating cyclically on the double-ended cone. But as soon as the twin particles are separated in space, one has to take into account that time-keeping is local (due to the presence of gravitational gradients that pervade space). That means the instantaneous precession phases drift apart, which is an ineluctable cause of decoherence. Instead of "spooky action at a distance" we must appreciate "not-so-spooky time-keeping at a distance" - a well-known feature of General Relativity.

[@nachoijp]

So we live in a lazy universe that only defines particl statuses when meassured, but otherwise it just aproximates them? interesting

[@jerk1921]

Exactly like a video game does.

[@arturgasparyan2523]

Obviously, since we live in a simulation.

[@TeodorAngelov]

Except they are not approximated but pretty precise(carrying way more info than the classical model).

[@ExistenceUniversity]

No, because every interaction is a measurement. It's not waiting for some human to see it. The universe is a plenum, there needs to be little stuff where nothingness is not, and so everything interactions and everything measures.

[@NeonVisual]

Gravity pulls inwards, gravitational waves flow outwards. The expansion of space is due to gravitational tacking as empty space has no mass, like a sail boat can move into the direction of wind while the wind is pushing everything else away if the sail is angled correctly. Mass is the sail, gravity is the wind. A theoretical sail in the negative angle is negative mass.

[@nikolaka007]

Both not the first comment and the first comment, is it superposition?

[@RobinDSaunders]

When discussing entanglement, I think much of the confusion can be cleared up by having a clear picture of joint systems and their states - this lets us directly see the distinction between classical and nonclassical correlations. For this, an image is worth a thousand words, but I don't have one so geometric words will have to do. (The following is just an overview - pictures or preferably animations would make a big difference and hopefully there'll be an episode on this at some point, but in the meantime those interested can probably find clearer and more visual explanations elsewhere): * Think of the states of a system as points in space. For example, one system might have states labelled A and B (the labels can be thought of as the outcomes we'd get when performing a particular measurement), and these would be two distinct points. States can involve probabilities: for example, a state with 0.5 chance of giving either measurement outcome "A" or "B" could be thought of as lying halfway between the original points. In fact, there's a whole line segment of probabilistic states stretching from A (outcome definitely "A") to B (outcome definitely "B"). We could even give A and B co-ordinates like (1,0) and (0,1). Then the point (p,1-p) is a state with probability p of giving outcome "A", and 1-p of giving outcome "B". With three possible outcomes, we get a triangle, with vertices say A, B, and C, or (1,0,0), (0,1,0), and (0,0,1). A generic probabilistic state of this system has co-ordinates (p,q,r) with p+q+r = 1 and each co-ordinate being non-negative. This all generalizes to any finite number of possible outcomes: four outcomes gives a tetrahedron, n+1 gives an n-dimensional "simplex". Note that A and (1,0,0) are actually two names for the same point, so we could equally write (p,q,r) = p*(1,0,0) + q*(0,1,0) + r*(0,0,1) as p*A + q*B + r*C. What if we combine two simple systems into one joint system? Say the first system has possible measurement outcomes "A" and "B", and the second has "C" and "D". Then the joint system has states AC, AD, BC, and BD, and as before these can be thought of as the vertices of a tetrahedron whose other points are all probabilistic combinations like pAC + qAD + rBC + sBD (again, p+q+r+s = 1 and all co-ordinates are non-negative). This picture lets us talk about correlations. If we take two separate systems with probabilistic states wA + xB and yC + zD, then there's a corresponding state of the joint system which is just the "product" of the two separate states: (wA + xB) ⊗ (yC + zD) = wyAC + wzAD + xyBC + xzBD (remember: w, x, y, z are numbers; A, B, C, D are points). In fact, the vertex labels AC, AD, BC, and BD are just shorthand for A⊗C, A⊗D, B⊗C, and B⊗D. Such a state of the joint system, which can be written as the product of one state from each system, is called a product state. These always lack correlations between measurement outcomes. For the example just given, wyAC + wzAD + xyBC + xzBD: measuring "A or B" gives probabilities w and x respectively, measuring "C or D" gives probabilities y and z, and neither of those measurement outcomes is correlated with the other. On the other hand, most joint states aren't product states and so do involve correlations: for example, the state 0.3AC + 0.2AD + 0.2BC + 0.3BD has a 0.5 chance to give outcome "A" or "B" and likewise for "C" or "D", but these outcomes are correlated: getting measurement outcome "A" means a 0.6 chance of getting "C" but 0.4 of getting "D", and vice versa when getting outcome "B". We say that these correlations are "classical" because they come from "classical" combinations of product states: the state pAC + qAD + rBC + sBD (with p+q+r+s = 1) is a classical combination of product states AC, AD, BC, and BD if all the individual probabilities p, q, r, and s are non-negative (as classical probabilities should be). On the other hand, in quantum physics (and various other "non-classical" theories), joint systems can have states which are *not* classical combinations of product states. For example, you might see a state like 0.4AC + 0.4AD + 0.4BC - 0.2BD (I haven't checked whether this could appear in quantum physics, but it's certainly possible in some of the nonclassical theories I mentioned). Notice that the individual "probabilities" 0.4, 0.4, 0.4, -0.2 still sum to 1, but now they don't have to be non-negative. Such a nonclassical or "entangled" state seems nonsensical at first sight, but if you work out the probabilities of individual measurement outcomes, you find that they're all well-behaved ordinary probabilities between 0 and 1. For example, the entangled state just described will give measurement outcome "A" or "B" with probability 0.8 and 0.2 respectively. However, because the "probability" of -0.2 assigned to outcome BD is negative, and we can never actually observe events to occur with negative probability, it follows that we cannot simultaneously measure both "A or B" and "C or D". This is closely related to the impossibility of simultaneously measuring conjugate variables (such as position and momentum) with absolute precision in quantum physics.

[@bedo2445]

the only thing spinning is my head.

[@Nebuch]

Incredibly interesting results. With this perspective, in a way we observing a state gradients that recognizable to the rest of the universe, like colors. But still they obey some strict rules and i think this is suspicious.

[@_vicary]

But when does the consensus happens between macroscopic human minds? When embedded into the macroscopic network of atoms, isn’t the whole theory of entanglement become invisible and thus untestable? This explanation is lacks logical satisfactory and in fact sounds quite dodgy to me.

[@tapksa]

Entanglement has been tested in much the way described 4:40. So it's absolutely, definitely not untestable, quite the opposite.

[@mikhailmikhailov8781]

We can perform the relevant experiments with small no.1 of individuals particles.

[@_vicary]

@tapksa Exactly.

[@davidwilkie9551]

One aspect of Spin is tangential orthogonality Inflation +/- "convection" displacements of resonances, which, in one aspect appears to be an "Accelerating Universe" of interference positioning, harmonic nodes of matter. It's a well known property of sound, that resonances conduct better, are better "projected" by someone playing an instrument, when the resonances of instruments and auditorium are matched appropriately. Something similar applies to resonant frequency projection in relation to e-Pi-i logarithmic resonance imaging function cause-effect of time duration timing modulation in/of Superspin, and the apparent distribution properties of Time In-form-ation.., Red-shifting phenomena.

[@MrREALLYK]

First

[@parsarahimi335]

Yes you are

[@anna.m8]

Fantastic visualization. Thank you!

[@Inhuman0]

PBS Space Time is awesome. So is the presenter by the way.

[@JanRiebe]

Thanks for this video! A couple of concepts just clicked into place in my understanding.

[@ArrovsSpele]

Hat down to this great episode. Really liked that you gave close attention to details of measurement problems. Additionally, how do we know that by measuring with magnetic field we just not align particles magnetic orientation? That is what we see in our macro world.

[@Android480]

PBS does a really good job with these. I'd be psyched on this if I was 12, and I'm still psyched on it as adult. I wonder what actual theoretical physicist think of the channel.

[@schmetterling4477]

It sucks, like almost everything on the internet that is about physics. Notable exception: the physics stack exchange. That's the real deal.

[@spencerwenzel7381]

I've never thought of entanglement in terms of conservation of angular momentum. It seems so obvious now. This just blew my mind.

[@piotrsuszynski9273]

This episode was really great and actually I'm amazed that this interpretation of Quantum Mechanics is not commonly taught. It gets rid of the wave function collapse - instead there's just growing bubbles of entanglements. And that's fantastic! The Schrödinger equation doesn't describe the wave function collapse and the Copenhagen interpretation just silently shrugs off what exactly is this collapse and what are the physics of it. Ok, the many world's interpretation is similar but if I understand correctly it's about many whole universes, not entangled-bubbles part of the universes, like here.

[@piotrm9260]

When in previous film you've multiplied these observers (with one eye) I knew the factor which glues the many worlds together is overwhelming entanglement. I see today we are closer to the true. From this we can learn that if you want to teleport an object you must erase its entanglement connections. Otherwise it will always be in superposition. Pozdrawiam Pana panie Żurek.

[@btc54723]

One of my all time fav episodes

[@gprivat812_my_selection6]

Hard to digest, but having the gut-feeling "it's worth it" motivates me to even more efforts! 🐱😇❗

[@Perseus3105]

Thanks for the video, cant even imagine the amount of effort you put into this, great video, love it :)

[@brettaspivey]

One of the most fundamental laws of physics is CPT symmetry. This should apply to entanglement just as well as other physics. So by invoking entanglement backward in time, many of these action at a distance paradoxes are explained. A quantum interaction can propagate backward in time just as well as forward in time.

[@SicilianDefence]

Tankiiiiiii uuuu! Finally i got the concept of measurements basis for axis distributions!

[@sstallsmith]

In the quantum world items can be in different states depending on how you measure them - this leads to the many worlds theory. It follows we can be in different states (many worlds) depending on how we think - a positive mental attitude can make a physical difference! With a positive mental attitude you'll lead a good life; split from the alternate worlds where you'll be the person who can't do anything right and always has bad luck.

[@Baloney108]

Its crazy because I fail my academic path and i'm so hook on quantum videos on youtube haha. It feels like im listening to a movie with an impossible plot to crack haha. Thank you to provide me with so much serotonin 🎉

[@ScottJWaldron]

Great video as usual! For this one I think I'll have to watch it a few times to get it. ;D

[@TheAmatyarakshasa]

I can’t understand 99.9% of what he says but I still keep watching all these videos.