why you can't explain qcd

[@tidenly]

"Angela Collier is my favourite KZbin science communicator" - Albert Einstein

[@BrianFedirko]

this quiote, I trust is from Uncle Albert, because it's true. Gr8! Peace ☮💜Love

[@andressigalat602]

"i was going to do that joke, but you got ahead of me." - Albert Einstein's first cousin once removed

[@GSBarlev]

​@@andressigalat602in other words, "A Einstein?"

[@dsracoon]

"Angela told me Feynman was a dumbass" Albert Einstein. Am I doing this right?

[@pinocleen]

"QCD on the lettuce" - A.E.

[@scolton]

The video really delivers on its promise, at the beginning of my shower I didn't understand QCD and at the end of my shower I still do not understand QCD.

[@idontwantahandlethough]

SUCCESS!!

[@thomasrivard9772]

You spend nearly 40 minutes in the shower?

[@scolton]

@@thomasrivard9772 no, but I do spend about 25. shaving takes a while 🤷‍♂️

[@mallninja9805]

@@thomasrivard9772 You don't??

[@autumrnk]

Glad i am not the only one who watches these in the shower

[@powernade]

"You can't explain it to a six year old because it takes 4 years of undergrad and 4 years of grad school-" Ok, so they must be at LEAST 8 years old. Got it.

[@aidanwarren4980]

Being delivered from the womb straight into Physics 101

[@DamienPalmer]

@@aidanwarren4980 Get that fetus into AP classes pronto!

[@bartroberts1514]

Takes about sixteen hours to teach all of the coding needed for simulation, though. PDEs, if you cut out the timewasting geometry, accounting math, and trains leaving Chicago, another three months. The real issue is all of QM is just models, and what's behind the models is only vaguely represented by all of QED and QCD, so possibly a six year old, undistracted by all the noise adults have in their heads might be Mozart, and all of us Salieri.

[@scarlettjoehandsome6130]

​@@aidanwarren4980I knew that guy

[@shApYT]

@@bartroberts1514 8 years + 1 day

[@janmelantu7490]

My favorite quote about quantum mechanics is from CGPGrey: “look, ‘spin’ and ‘whirl around’ don’t mean what you think they mean. In the quantum world, words mean NOTHING, there is only MATH.”

[@umbraemilitos]

Math is a language, though. The reasons for doing the math, and the connection to experiment, can absolutely be written in English.

[@schok51]

​@@umbraemilitosyeah but quantum theory is known to be hard to make sense of through natural language. "Shut up and do the math" is usually what professors end up saying to students trying to grok quantum theory in their existing world model.

[@umbraemilitos]

@@schok51 The blackbox properties of quantum mechanics are up for debate and philosophical discussions, which can be done in English. However the mathematics and experiments are much easier to do in English. There is a flow of probability for quantum states, and the expectations and transitions of those states are not so abstract that we can't discuss or describe them.

[@schok51]

@@umbraemilitos I'm not saying it can't be talked about, I'm saying natural language is not an appropriate encoding for all knowledge, there's not a 1:1 equivalence between all math and english language such that any mathematically sound notion can be as clearly explained in English without ambiguity and overloading words such that understanding the math itself is a prerequisite. Language is not evolved around that kind of need. Anyway I'm not a quantum physicist or philosopher. If you are and think you can resolve any ambiguity or apparent unintuitiveness in quantum theory by explaining everything in natural language, i encourage you to do so and provide links to what you consider good attempts.

[@umbraemilitos]

@@schok51 All mathematics is taught in "natural language." All mathematics was developed by human curiosity, and was described and dreamed about in those terms. The symbols of mathematics are little more than a shorthand for language. They are not a replacement for it.

[@DannyBeans]

I like Feynman's opposite quote: "If I could explain it simply, it wouldn't be worth a Nobel Prize."

[@zym6687]

I completely disagree with that there are plenty of examples where a nobel prize was awarded for things that can be explained simply. Just because something can be explained more thoroughly doesn't at all mean it hasn't been explained. Feynman is just an ass

[@fightthepowerman]

I like the quote of some pathetic random KZbin commenter when he said "maybe the complexity of a scientific achievement isn't what causes it to be award-worthy"

[@RegiJatekokMagazin]

if AI would know everything, we dont even need to solve anything, why would we work, to reinternalize something in our head? how to dig the dirt?

[@ktxed]

That's probably not a Feynman quote. I suggest watching Angela's recent take on Feynman's legacy.

[@DuskoftheTwilight]

> sign up for a qcd lecture > Ask the professor if it's really about qcd or if it's just qed > They don't understand > Prepare a half hour KZbin video about the difference between qcd and qed > They laugh "it's a qcd lecture" > Attend > It's all qed

[@dominicellis1867]

The last 10 seconds is the professor saying QCD is beyond the scope of this QCD lecture.

[@Perserra]

QED ... QED. 😁

[@pmikky6808]

> mfw

[@smuganimegirl769]

"Those are cartoons. They're not math." Angela shoving a category theorist into his locker.

[@bohanxu6125]

shoving mathematicians into lockers? well... that's what physicists do on a daily basis because the mathematicians keeps bickering about rigorousness or something

[@raum_dellamorte]

I laughed so hard a frictionless spherical cow shot out my nose, keeping in mind that I only say that to simplify the math.

[@penttierareika4837]

Sad Oliver Lugg noices

[@smort123]

@@penttierareika4837 Oliver Lugg can define the set of all things that make you feel pain

[@fariesz6786]

_•said monadic noises•_

[@KMO325]

“Albert Einstein catching strays from Dr. Collier is one of my favorite things about this channel.” - Mark Twain

[@rudyj8948]

Damn, many illustrious thinkers on here watching A Collier, i had no idea

[@savage5757]

1:10 you can't believe everything that is written on the Internet © Einstein, 1990 🤣

[@dannydetonator]

"I hear the voices of vegetables" - A. Jones

[@MarcusStenberg]

"Actually it was Samuel Clemens who said that" - Eldrick Tont

[@kylehill]

I take notes on your videos. Let's start a podcast.

[@marko1395]

10/10 would watch.

[@billyalarie929]

PLEASE I NEED THIS

[@byrnemeister2008]

I hope this conversation is happening off line!!

[@Marina_DU]

Uuuhh two of my KZbinr nerds interacting 🙊

[@drxyd]

Would. Watch, would watch.

[@pink_plasticbag]

"wait, this video has nothing to do with war. why am i here?" - Sun Tzu

[@jeffreyatlee8785]

"Shut up dude, it's quantum" - Richard Feynman

[@sjorgen9122]

Watching at 2x speed so I can not understand QCD in less than 20 mins

[@xponen]

By watching at higher speed, it actually enhances understanding because all points are presented temporally closely together, this mitigates issue like 1) low memory retention (memory fading before all points are presented) and 2) ADHD by focusing all attention at shorter time frame.

[@thomasj.treder7971]

@@xponen Thanks! I'd been steadying myself to rip through at 4x -- *or more!* -- so I could not understand QCD even faster than my peers. Now that I know it won't work, I can get ignorant about something else instead. Saved my afternoon!

[@TheDemethar]

you forgot to give it to the next person

[@freddan6fly]

Take a big drink on next party and explain it to someone not nerding physics. They will really understand it.

[@anotheral]

I would like to propose that "Quantum Gastrodynamics" is a way better term for weak force flavor interactions.

[@thenonsequitur]

That would legit be a better name.

[@dashoc9430]

Oh, the flatulence jokes just waiting to be told… :P Just in case it satisfies anyone's curiosity, if we were to be strict with our Greek roots, I believe the topic would be called "quantum geumodynamics" - "gastro-" more precisely comes back to "stomach"!

[@mal2ksc]

@@dashoc9430 But cooking is known as "gastronomy" when attempting to sound important. I say they're trying to incite chaos along the lines of cosmologist/cosmetologist. About the only thing those two professions have in common is that they both need proficiency in Photoshop.

[@dashoc9430]

@@mal2ksc I don’t know exactly what the OP’s intentions were, but I took their comment to be humorous (and found it funny myself). My comment isn’t meant to negate it, but to complement it. Like the neutron to the OP’s proton, or the side to the their main :)

[@GlennElert]

"Gastro" (γαστρο) is Greek for stomach, not flavor. Quantumstomachdynamics?

[@TanyaLairdCivil]

"Doesn't that suck for Einstein?...People just make stuff up and they say Einstein said it." -Albert Einstein

[@analoghabits9217]

always refer to yourself in the third person - AE

[@Flesh_Wizard]

"my balls exploded" - Albert Einstein

[@mosubekore78]

He died already, he doesn't care

[@JRV9113]

"These videos are just her what grinds my gears rants." -Albert Einstein

[@tetronym4549]

I mean yeah isn’t everything he said made up by someone? He wasn’t real, I thought he was a theoretical physicist.

[@nicovaldes3850]

I think you did a great job of explaining most of the stuff and got close to describing what's hard about QCD, but didn't quite get to the punchline. The hardest part about QCD isn't that the Feynman diagrams are more complicated, or that there's so many gluons and flavors - that's an annoying thing for sure, but people can still compute diagrams up to a couple of loops (especially using Mathematica packages). The hard and beautiful thing about QCD is that if you wanna describe the inside of a proton, it just doesn't make sense to compute Feynman diagrams because what's going on inside is nonperturbative. Feynman diagrams wouldn't give a meaningful answer in any way to the problem, even if you could compute and sum all of them! That's why we need to do the path integrals with lattice QCD. You got close to mentioning this when you talked about perturbing QED, but I think it's worth pointing out as another pitfall of Feynman diagrams. Not only are they a cartoon for the math, they are sometimes cartoons for math that we shouldn't be doing in the first place for certain physical questions. (I know that the main point of the video wasn't to explain why QCD is hard, just hard to explain. But I guess my point is that it's hard to explain if you start from Feynman diagrams, precisely because they don't work in the theory. But explaining it with just path integrals might be "easier"?) Cheers and thanks for all the fun the content!

[@Matt_The_Hugenot]

I love relearning all this stuff. When I studied it 40+ years ago unitary symmetry was the model and quarks were still somewhat controversial. Now everything's changed and I'm learning from people half my age.

[@carolynr570]

“W boson?? More like L bozo”- my attempt at a joke

[@MM-vs2et]

L elementary particle

[@jaspershepherdsmith9047]

It's a good bit, congratulations.

[@douggschmiddy9950]

Your attempt at a joke? more like your success at a joke. - my success at a joke

[@user-en5vj6vr2u]

“What the fuck is a W boson” -Albert Einstein

[@Gil3490]

hmmm bosom

[@odinson8761]

I don't know if you have ever tried to explain something to a 6 year old, but they will ask you why about a thousand times while you are explaining something. To me, this is the root of the quote. It is not about being able to get the 6 year old to understand or have them be able to explain in the future. It is about being able to answer all of their why questions. If you can accurately answer all of their questions then you fully understand the subject.

[@freddy4603]

I wish this comment was the most liked one

[@Michael-kp4bd]

And chances are that you do not _fully_ understand any topic, and this is one of the most effective ways to recognize the things you don’t.

[@5naxalotl]

i want to give you half marks for this. i feel like the skill einstein is talking about is the ability to conceive of a useful model that can be built out of simple chunks in a recursive process where each step can be stamped as an image in a small mind. consider one of those dog dancing competitions, for example, where the trainer has trained the dog in an inordinate number of little elements, including the stitches that link them into sequences. dumb dog, complex result. however, i also know exactly what you're talking about and i think it's an admirable skill to be able to answer a child's but-why questions until the child is exhausted before the adult. this is a different but similar process of being able to package concepts for a small mind, and requires a really secure sense of philosophy to understand all things in terms of well defined components. the difference though is that in one process the adult is controlling the structure because they can see what the end point is and how to get there, and in the other process the child is allowed to drive. i realise it can be a fine distinction

[@Michael-kp4bd]

@@5naxalotl great elaboration. Of note though is that Einstein did not say that quote. Is there a different one you’re referring to?

[@meesalikeu]

@@5naxalotlyou never let a child start on that path without pressing them to tell you what they think or to give you a guess why first - that tends to slow the why why why’s down.

[@matthieuhenocque7824]

The more I listen to Dr Collier, the more I realize I don't know shit about fuck but also the more I enjoy realizing this about myself. Dr Collier is a superhero. Her power is knowledge. Her secret weapon is an anti-crackpot-Dunning-Krueger-syndrome-theorists mischievous smile. Thank you so much.

[@clvr51]

Dude this is pure gold. I agree with every single word and laughed my ass off from start to finish. Hats off to you my friend.

[@werdnarotcorp8991]

@@clvr51 Me too.

[@werdwerdus]

you were able to finally put into words how I've been thinking about her, perfection

[@paavobergmann4920]

Yup. That.

[@Microplastics2]

She easily destroys the false veneer of youtube/online-aquired science knowledge that so many have. Idk I watched a lot of pbs space time and though I at least knew a bit about quantum mechanics, but after watching her stuff I quickly realised that I don't know shit...

[@bronzedivision]

I'm extremely grateful to this video for showing me that a Saturn V plushy not only exists but is now also in my online shopping cart.

[@mk1st]

Plushy? I thought it was one of those wobbly AI generated things.

[@NeostormXLMAX]

There is a very good quote from peter watt’s echopraxia “But people have an unfortunate habit of assuming they understand the reality just because they understood the analogy. You dumb down brain surgery enough for a preschooler to think he understands it, the little tyke's liable to grab a microwave scalpel and start cutting when no one's looking.”

[@bobland5699]

At CalTech in 1970 (and probably in his books later) Feynman described trying to tell his father, an intelligent layperson, about what he did. I remember Feynman telling how, when his father asked “when the neutron becomes an electron and a proton, was the electron always there ‘inside’ the neutron?” “And I couldn’t explain it to him.”

[@idontknowwhatahandleisohwell]

Hell, if I could explain it to the average person, it wouldn't have been worth the Nobel Prize."-Richard Feynman.

[@RicardoMarlowFlamenco]

But he did explain it to him. via his son talking about the “word bag” in his stomach that ran out of words. 😂. But maybe he got that analogy post 1970, yet it was a problem solved.

[@dv9051]

I remember someone asking if there was an electron inside the nucleus during beta decay. This derailed the lecture, and the question never was really answered.

[@vegapunkrecords]

Does anyone have a source for this? Would really like to read/watch the full speech/lecture.

[@MattMcIrvin]

I can explain that! I'd just say "no". (that's close enough to being the right answer)

[@jelmar35]

Einstein once said: "I have predicted many things in my life. My theory can predict Mercury's precession. My theory predicts black holes. But the prediction I am most proud off is that 12 year olds will incorrectly attribute quotes to me on the internet."

[@bridgetown1966]

"you don't think the 5 year old understood machine learning, do you?" not even that far into the video and i'm already cracking up

[@GSBarlev]

"Don't go around grabbing five year olds." -Angela Collier, science communicator

[@amy_grace]

"Explain machine learning, CHILD!" 😂

[@alphacat4927]

Yea she is really funny.

[@SimonBuchanNz]

My best understanding of that "Einstein" quote is that giving a satisfying simplified explanation of something requires a much better understanding than what you need to just feel satisfied by your own understanding.

[@zorgus2002]

I think the important thing is you successfully taught me that I don't need to know any more about QCD. I've tried before, but now I am happy to stop worrying about it. Thanks for the video Angela!

[@jameslloyd2540]

I'm really glad that this professional science communicator was able to ensure I understood that I do not understand QCD.

[@BillBrasky5351]

QCD is the most complex, sciency sounding name I've ever heard. Even more than the mathematics of quantum neutrino fields --Albert Einstein

[@AstarionGrle000]

😂

[@Rockyzach88]

Now start mixing different cool sounding sciency professions together. How about Quantum Computational linguistic Chromo Dynamics.

[@BillBrasky5351]

@@Rockyzach88 you've embiggened science with your cromulent vocabulary. 🫵🫡🍻

[@ohno5559]

Mathematics of wonton burrito meals. Got it.

[@BillBrasky5351]

@@ohno5559 in ur proposal, are u going to dynamically cram wontons into the burrito? With a glueon layer of cheese? Or will the burritos be inside the wontons?

[@ravenlord4]

When I was 6 years old I would get into trouble for mixing the colors of my Play-Doh. Imagine my horror if someone had tried to teach me that it was ok for quarks.

[@GSBarlev]

Physics parents: "No! You don't have the same quantity of red, green and blue! That's illegal!"

[@AdrianBoyko]

You should read about how your brain perceives colors. You’ll probably be so traumatized that you’ll gouge your eyes out.

[@DamienPalmer]

@@AdrianBoyko So... you *shouldn't*.

[@AdrianBoyko]

@@DamienPalmer I already did 😵

[@raum_dellamorte]

Hold on... I really think we need to go back to the maths here so you can more fully grasp how everything you know about Play-Doh is wrong.

[@ABC_Guest]

34:19 ""QED, which is a mathematically rigorous proven thing" - this is a funny quote because that's what "quod erat demonstrandum" basically stands for

[@sherlock_norris]

You definitely can explain QCD to a six year old, it's just the explanation takes usually about two decades.

[@roger5059]

Then you explained QCD to a 26 year old

[@vez3834]

​@@roger5059 would it be more accurate to say you explained it to a 16-year-old? That's the average age at least

[@stephanieparker1250]

“ I’m saying words but math math math.” I think I need a T-shirt that says this.

[@mallninja9805]

I'm procrastinating when I should be studying for my differential equations final exam tomorrow, and I saw this comment just as she said it. I feel this sentence in my soul...

[@ypey1]

Einstein said that

[@stephanieparker1250]

@@ypey1 I knew it!

[@stephanieparker1250]

@@mallninja9805 good luck on the exam! 🙌

[@werdwerdus]

please ❤ but a tank top haha

[@Stirdix]

My explanation of why QCD is hard (for physicists to do, which is kind of a different matter from why it's difficult to explain) is to show Feynman diagrams and explain roughly what they mean, then say: "you can always draw more and more complicated diagrams. With QED, these diagrams get less and less important, so you can often get away with ignoring them past a point, and get a pretty good answer by only computing the simple ones. With QCD, the complicated diagrams get *more* important, so you can't get away with that kind of trick."

[@r3lativ]

That's a great point.

[@dinobotpwnz]

Exactly. The main reason is the sign of the beta function and that was missing from the video.

[@modolief]

Very informative, thanks!

[@pierrecurie]

Even ignoring the Landau pole, the # of diagrams grows too fast. It's an asymptotic series. The QED coupling constant is small enough that a reasonable # of diagrams leads to a "good enough" answer.

[@frederf3227]

QCD is the 1+2+3+4+... = -1/12 of physics?

[@SkorjOlafsen]

"I never said half the things I said." - Yogi Berra

[@smoceany9478]

"i never said half the things i said" - babe ruth

[@GSBarlev]

"First time?" -Mark Twain

[@misterjaxon2559]

I wonder if he really said that.

[@Sam_on_YouTube]

Berra actually said a LOT of really funny things that are well documented. There's a bunch he didn't say, but I think that one is real.

[@ad3larde]

I think that quote was mine - Ghandi

[@neruval8998]

>Showscryptic glimpses of a theory about a force with three charges that binds matter on the deepest known level. >"Yeah it's kinda boring. Who cares about what's inside a proton." I do, Angela, I do very much care what's inside a proton.

[@GraceOliviaf7y]

Tax laws can be so complex, and it’s super helpful to break them down like this. Understanding how different policies can impact our finances is crucial for making informed decisions.

[@OscarBarnaby3k]

Making profitable investments during this time of political change can be risky without that insight. For me, working with an adviser is the best first step to navigate these complexities and make informed choices.

[@MatthewAidan4ns]

I think having an investment advisor is the way to go. I've been with one because I lack the expertise for the market. I made over $490K during the recent dip, highlighting that there's more to the market than we average folks know.

[@NikolasMartine01]

Hmmm this is quite interesting, Please can you leave the info of your investment advisor here? I’m in dire need for one.

[@MatthewAidan4ns]

Nicole Anastasia Plumlee can't divulge much. Most likely, the internet should have her basic info, you can research if you like.

[@NikolasMartine01]

I just googled her and I'm really impressed with her credentials; I reached out to her since I need all the assistance I can get.

[@giovannironchi5332]

I mean, which 6-Years old cannot understand irreducible representations of SU(3)?

[@3zdayz]

Still prefer R3. A simple sphere and no tangrnts

[@steffenbendel6031]

A 6 year old in a woke school.

[@bridgetown1966]

this gotdamn american school system... when i was a kid, it was the three R's: readin', ritin', irreducibl' representations of SU(3)

[@rynabuns]

@@steffenbendel6031Can you explain "irreducible representations of SU(3)" to a 6 year old or are you "woke" as well?

[@edwinrollins142]

​@@steffenbendel6031what is a woke school and why is that a bad thing?

[@TheHunterGracchus]

I used to have an abstract algebra professor who told us that you don't understand a proof until you can explain it to your teddy bear.

[@birdbrainiac]

If the teddy bear understands your explanation, you have an entirely different problem on your hands.

[@xantiom]

This is valid. In programming it is known as "rubber duck debugging" which is used for solving problems, at which you get into an answer while you are trying to describing the problem to someone else. To exploit this phenomenon, instead of bothering a friend to listen to you, they place a rubber duck and explain their hurdles and where they are stuck until you get an insight while you are bitcjing about it.

[@Michael-kp4bd]

@@xantiommy work just had an outing and we ended the night at Dave & Busters, where one of my coworkers used all her credits on the rubber duck claw machine (honestly best value, cuz your credit doesn’t get used until you get a duck). Anyway, she gave them out and now I have an actual rubber duck to rubber-duck with as I develop. My coworkers didn’t know the term, and I showed them the wiki article, and the article’s main picture shows the same lil’ guy I got! Anyway, my troubleshooting ability is about to skyrocket

[@AntsanParcher]

This makes way more sense than the saying it's a spoof on.

[@timothyclancy6919]

One could make a great debate between Lincoln and Einstein with all the things they never said.

[@KitagumaIgen]

You're quoting Socrates, right?

[@FPSIreland2]

@@KitagumaIgennah that’s Plato

[@GSBarlev]

What frustrates me about comments like this is that quotes wrongly attributed to Lincoln and Einstein are, in fact, wrongly attributed to Mark Twain! 😉

[@zamplify]

Lincoln had a secretary named Einstein. Einstein had a secretary named Lincoln.

[@chrisl6546]

With Yogi Berra as moderator

[@ftircom]

Thank you. Fun explanation. When I got my Ph.D in physics, we were searching for quarks. I heard Feynman, Gell-Mann and others speak on Unified Field Theory at an APS meeting in D.C. I gave my first paper as a grad student and went down stairs after the talk. There was a standing room only crowd in the Ball Room. I wiggled in and found a place to stand and not block others. After the intro, Feynman spoke. Feynman had long hair light brown hair down to his shoulders. He was young and spoke with the accent of a Brooklyn truck driver. He opened with a pretty bold statement that was close to "I don't know what you know because I never read the literature". Someone gave his talk (Gell-Mann?) writing on an opaque projector with a black marker blocking 50% of the image (equations) on the screen with his head. We have still trying to do Unified Field Theory. Fun video.

[@ripper132212]

the steady pace and enthusiasm with which you present a really cool topic (at the pointy end of science) makes for a great video

[@johngregor6743]

My mental model of the relative complexity: QED: watching 2 or 3 billiard balls run into each other on a nice smooth pool table. QCD: watching a writhing ball of spaghetti the size of the solar system and oh yeah, the spaghetti is moving at nearly the speed of light and is made up of super-powerful magnets.

[@Zeroisoneandeipi]

I think I can summerize QCD. It is a game where a lot of 6 year old quarks spin on thier hands or feet or jump up and down. They wear red, green or blue T-Shirts, some of them are a bit strange but others are charming. Then there are other players which can use glue to catch the quark players. The rules who can catch whom are complicated, you have to consider the color of the shirts, how they are spinning, relativistic effects and the probability of sun shine during the game. The rules are so complicated that there is no way to calculate the exact outcome of the game you can only do some computer simulations. And I forgot to mention that the best players can play as bosons which makes everything more complicated.

[@jaybleu6169]

Wibbly wobbly, timey wimey... stuff

[@samanthamacguire7881]

"you really think someone would do that, go on the internet and tell lies?" -Aberham Lincoln

[@jocabulous]

Aberham Linkin

[@lbgstzockt8493]

@@jocabulous Aberham Linkin Park

[@quarkonium3795]

@@lbgstzockt8493Abracadabrahamilton LinkedIn

[@conscientunit1157]

-shinzo abe lincoln

[@loveless-savage]

I think this is misattributed, didn't Einstein say this?

[@MattMcIrvin]

One of the problems is that the approach that makes the leap from QED to QCD seem simple and natural is a really mathematically abstract one, where you take *gauge symmetry* as the most important thing that determines the whole theory. Usually when you study electromagnetism in a quantum mechanics class, gauge symmetry comes in kind of late as an advanced topic. If you express electromagnetism as potentials, you can do things to the potentials and simultaneously do something to the phases of the matter wave functions, and it's unchanged even if you do it differently at every point in space-time. And then you turn it on its head and say that gauge symmetry is what *determines* electromagnetism--you start with the relativistic QM of matter particles, then add gauge symmetry and the potentials have to come in, then you somehow breathe life into those and treat them as aspects of a physical field and you've got QED. Then you say, well, the gauge symmetry involved a mathematical object called a Lie group, and for QED the group is the simplest nontrivial one you can use, "U(1)", which is actually the same as a circle (messing with phases of the wave function, which go in a circle). Then you go from "messing with the phase" to "messing with some multidimensional space of color charges", which is a different Lie group, and QCD falls out, and then you mess with other quantities (the "flavordynamics" stuff Angela was talking about) and a big chunk of the Standard Model falls out. And whether the force carrying field has charge has to do with whether the group operations are commutative. But the class has this big mountain climb to even get to that point and it's very abstract. How do you even do that in an elementary context? I haven't quite figured it out. I recall Heinz Pagels trying in his book "The Cosmic Code", but it was a stretch.

[@Lolleka]

You don't. You just don't ask anyone that hasn't already climbed lots of mountains to follow you on a tour of the Seven Summits.

[@MattMcIrvin]

@@Lolleka oh yeah, and then Heinz Pagels died falling off a mountain

[@DavidvanDeijk]

Thanks, hope this is true because then i learned something

[@MattMcIrvin]

@@DavidvanDeijk This is how all the forces in the Standard Model are constructed--it's all gauge theory. The part I left out is that if you do this you get force-carrying particles that have no mass, but the W and Z particles that carry the weak force are very massive, and that's where the Higgs field comes in. Even general relativity is a different kind of gauge theory, where the gauge transformations are on space-time.

[@jaybingham3711]

Maybe the elementary context can be fortified informally. YT has numerous high-quality videos that can serve as executive summaries much like what you went over here. Check out Highly Entropic Mind's episode "The math of how atomic nuclei stay together is surprisingly beautiful."

[@electro_fisher]

I have been trawling various wikipedia articles every so often for years trying to understand the "but why" of QCD, so this is great for me

[@astroalpha91]

This is one of the best and most genuine “explanations” of the standard model I’ve come across on KZbin. And I’ve spent the last three years doing my phd at CERN on explaining particle physics.

[@rokmedves8503]

Hi Angela! First of all, I loved the video! But I wanted to add on to what you said at the end -- that QCD can only be evaluated numerically (via lattice QCD). I just wanted to say that absolutely not! Most experimentally-relevant calculations of QCD are done completely analytically. It's literally what I did for my PhD and the ATLAS collaboration was even able to measure and compare to our analytical predictions. I know this isn't well-known in the community, so here's a bit of background: The idea that QCD can't be computed perturbatively ("knowing which Feynman diagrams matter") is because the strong coupling alpha_s is very large (0.118 at 91.2GeV, compared to 0.007 of QED). However, since alpha_s runs, it gets smaller as you go to higher energies (asymptotic freedom, as you mentioned in the outro). By the time that you get to experimentally-relevant energies (i.e. 13.6 TeV at the LHC), alpha_s is again small enough to be able to treat the theory as being perturbative. In fact, at experimental energies QCD is basically just fancy QED. So, recap: At small energies you need lattice QCD to say anything tangible, but at high energies QCD is just a regular perturbative theory. There is one additional complication however: The fact that colliders collide protons, which are low-energy QCD objects, and not quarks, which can be treated perturbatively. It turns out that this wrinkle gets handled by something called a "parton distribution function", which essentially connects quark/gluon cross-sections with proton cross-sections. In fact, because of this, your typical QCD experimental prediction pipeline looks as follows: 1) Experimentalists measure these parton distribution functions at other experiments, 2) A theorist computed the cross-section for some QCD process completely perturbatively/analytically, 3) They multiply their result with a parton distribution function. And voila, you've got yourself a phenomenological prediction for a proton-proton QCD experiment!

[@sillygoofygoofball]

thank you for saying this, that really bothered me

[@htspencer9084]

Nice!

[@htspencer9084]

Do you think this would reach general undergrad level education anytime soon? Obviously not its most verbose form!

[@dng88]

Should collaborate with her and do a video

[@lukflug]

@@htspencer9084 I'm currently a bachelor student, and I did learn about some of this in the 4th semester. I also took a particle physics elective where they went slightly deeper. Ofc it didn't go too deep, but we did have stuff like Parton distribution functions (at first in the context of deep inelastic scattering and neutrino-nucleon scattering), we looked at the classical QCD Lagrangian, we calculated some cross sections from tree-level Feynman diagrams (iirc for the Drell-Yan Process and R ratio for electron-positron scattering), which involved stuff like Gell-Mann matrices and color factors.

[@jeanf6295]

There is a reason for QCD : the subnuclear zoo. In the late 60s the number of particles discovered using particles accelerators numbered in the hundreds. QCD brought that mess down to a handful.

[@billyalarie929]

“Subnuclear zoo” is one of the wildest phrases I’ve ever heard

[@craiggersify]

“Quantum Flavor Dynamics” sounds like the motto of a New Age Guy Fieri

[@dekumarademosater2762]

"Quantum Flavour Dynamics" needs a t shirt. A lickable t shirt.

[@clvr51]

I instantly thought it'd be a sick name for a math rock band lol

[@BertrandLeRoy]

What really impressed me when I learned Feynman diagrams is that they’re not cartoons, but notations. How expressive they are while maintaining a 1:1 relationship with complex equations was mind blowing to me.

[@perplexedon9834]

After almost a decade of having a rough idea of what gluons are and what they are doing, I just now realised that gluons are called gluons because some physicist thought "hey these things are pretty strongly held together, its like these force mediators are the glue!" And now I am angry. Edit: I paused the video and posted this comment at the point literally 5 seconds before Angela articulated and then shared in my pain

[@andressigalat602]

"Don't go around grabbing five year olds" - Angela Collier (but I'm pretty sure Albert Einstein said it first)

[@jloiben12]

There may be a lot of made up quotes of Einstein, but he is a very good frame of reference a range of things. Like how it took Einstein 4 years after getting his PhD to finally get a professorship gig. And what’s even more crazy is that it took him four years after his miracle year, after producing four seminal pieces of research that also includes his Nobel-winning work, to get a job as a professor. If it took a Nobel laureate 4 years after he did his Nobel-winning work to get the job he wanted…

[@capnmnemo]

Well, maybe Mileva was busy and couldn't do the work or him.

[@DanGRV]

"There may be a lot of made up quotes of Einstein, but he is a very good frame of reference a range of things." -Albert Einstein

[@d3line]

Perhaps it's my background as a programmer, but I really don't see the problem here. For me it's kinda backward, most of the time I don't have an elegant mathematical model, or even an algorithm for a particular problem, so for me "let's just brute force (if feasible) or simulate" is the first kind of solution I go for. Finding or creating a neat algorithm that runs fast and produces the exact solution is a nice cherry on top, you use it if you already know it or if your code *must* run fast. Having a closed-form mathematical solution, a formula that just spits out an answer is like having a surprise birthday present. For me, the thought that reality doesn't fit into a math model is just a base assumption. I'm very happy to be proven wrong, but the closer you get to reality, the more factors your program must consider - the rearer such happy accidents occur. Like, generating _the_ optimal schedule for a school that considers a basic set of restrictions (no double-booking of instructors, classrooms, and students, balanced loads on students and faculty, no excessive movement across the building, etc.) is already computationally intractable. And that's all in the macroscopic world, so no wonder that we can't have exact probabilistic models for the QCD. It's kinda amazing that we can solve a hydrogen atom!

[@trolleymanV]

Love this comment, I completely agree (probably also because I'm a programmer)

[@jell0goeswiggle]

In addition to the NP problems, simulating natural phenomena is messy on its own. The two tests are: "is it fast (enough)" and "does it look plausible (enough)". Obviously how those are weighted varies on what you're trying to do (1 second of simulation per day is acceptable for like, Pixar, but certainly not for Nintendo). Even in the macroscopic here, there are tons of things that get commonly ignored because they play so small a part in the classical physics. (E.g. approximating friction as a simple coefficient, ignoring aerodynamics, etc. intra-molecular interactions in liquids, etc. depending on the ~~field~~ domain.)

[@RobertOrton]

I now have a much better understanding of both QED and QCD. Thanks! You do realise the incredible effectiveness of overloading the terms of colour and flavour to describe something that can never be directly experienced by anyone ever is such a genius approach to science, mathematics, language and art expression? It will take the application of everything that we are and everything we can be to comprehend everything in this existence fully. I think we are making good progress.

[@iansanford6544]

The pain on your face as you got out the "they're called gluons because... they stick... things together... like glue" xD

[@Aeon135]

I left school when I was 14 and even then I wasn’t great at math or science. I didn’t understand almost any of this. I still watch all your videos the whole way - there’s something so enjoyable about someone talking about a very specific topic they have mastery over.

[@NotreDanish]

23:31 I think you make a really good point about the Feynman diagrams giving people a false sense of understanding, and especially about the whole “antimatter does not go backwards in time” thing

[@GSBarlev]

She covered this in depth in another video, and while I was initially pretty... defensive? about the interpretation, because-hey, the math works-her larger point about "unphysical" solutions to equations (like Dirac Holes) has ultimately won me over and disabused me of much of my juvenile Feynman Fanboism.

[@3X3NTR1K]

We should describe it differently wrong ways instead. Like: "Matter and antimatter both go forward in time, but antimatter does it walking backwards."

[@Sturzfaktor2]

@@3X3NTR1K I now imagine a little positron constantly looking over its shoulder in order not to stumble into a nearby electron while walking backwards.

[@notapplicable7292]

Thanks! I now have a full understanding of QCD from this 30m KZbin video

[@mikechmielewski386]

That’s exactly what Einstein said!

[@Risu0chan]

If your average 5yo child is already familiar with advanced linear algebra, complex matrix calculus, Lagrangian mechanics, Dirac's quantum field equations, non-abelian Lie groups and the Yang-Mills gauge theory, yes, I think you can explain QCD to them.

[@Wick9876]

Think of how stupid the average 5yo is, and realize half of them are stupider than that. They may not have even mastered their Dirac.

[@TheNeonParadox]

This video reminds me of that time I brought a proton and a gluon to my favorite bar. We had a strong bonding experience. What a positive interaction it was.

[@DJRonnieG]

😆

[@ChristopherSadlowski]

Go to bed. 👉 Go to bed right now and think about what you said... 😊

[@TheNeonParadox]

@@ChristopherSadlowski 🤣🤣

[@dominicellis1867]

Why did the quark fall off my school project? Because I forgot to put the glue on.

[@johnclawed]

Until the 1800's, the popular perception was that bishops were highly educated, so all common aphorisms were attributed to one bishop or another. Then they were mostly given to Einstein. In the 1990's people who had just discovered email began attributing complete articles and speeches to either Bill Gates or Jay Leno, alternately. I always thought it was strange that they both had the same writing style.

[@robertarmstrong3024]

Thanks!

[@SpaveFrostKing]

As someone who doesn't have a physics degree and sucks at advanced math, this video taught me basically everything I'd actually want to know about qcd.

[@thylacoleonkennedy7]

13:26 "Behold! The field in which I grow my equations. Lay thine eyes upon it and thou shalt see that it is -incredibly complicated- barren.

[@GSBarlev]

I wanted to know where this quote originated (expecting some 19th century romantic) and was wildly disappointed that the original is attributed to *Hank Green.* But then I dug further and found that, in keeping with the theme of the opener, it's a misattribution (he _popularized_ it but didn't originate it)!

[@tomasroque3338]

This channel is a gift to the world. I have more than once thought about transcribing these videos, adding visual explainers to the pages, and printing them out as accessible pamphlets! (I haven't, though... copyright's a bitch!)

[@DJRonnieG]

The main obstacles to these sorts of ideas are our procrastination and the excuses we make for ourselves. Copyright, shmopyright! Jokes aside, I can see how copyright is a genuine obstacle, but if you're really determined, try something short and simple. You can fit a lot of info in a tri-fold brochure (double-sided).

[@tomasroque3338]

@@DJRonnieG I did make an A3 horizontal scientific poster for the "Why aliens won't be made of Silicon" video! And I mostly 'scripted' one other pamphlet of this sort too. I just wouldn't actually distribute/sell these. They're more like pet projects for myself.

[@DJRonnieG]

@tomasroque3338 I hear you, I've done my own fair share of pet projects in various forms of printed material. There's something rewarding about creating something nice in print that you can hold in your hand. It's long overdue for me to make a "turtle care pamphlet". So many people adopt Red-eared sliders with precious little information about their needs. 🐢 In any case good luck and if you ever want to share any finished project, feel free to drop me a comment.

[@tomasroque3338]

@@DJRonnieG Wow, I love that! I've laid out plans for a custom chess board where each piece is a different type of turtle (the movements and playstyle being analogous to each turtle's behavior and traits). But it would cost some to built it, and that's the kind of thing I'd have to pay someone else to do.

[@GingerWithEnvy]

I remember taking group theory and think "god this is tricky and weird, but i think I get whats going on kinda" and it helped me kinda understand what was going on in my QED lectures, then at the end of the group theory module they were like "okay, so if you wanted to try to apply this to QCD, youd also need to be keeping track of colour and flavour" and that wasnt to describe the interactions that was just to understand the math objects youd have to use before you look at interactions, and i remeber thinking "oh god please no" and fortunately the lecturer then informed us we didnt need to care about that because that wasnt on our course.

[@manfredfursich6779]

Dear Angela, I saw your KZbin video about quantum chromo dynamics and I was very impressed how you were able to explain this difficult issue in an understandable way - at least for an audience with some scientific background. Another interesting topic is quantum gravity. There are several approaches to this task but none of them is currently regarded as broadly accepted standard theory. I like the asymptotic safety quantum gravity approach, because it is similar to the QED and QCD approach. But as a layman I cannot express a profound opinion. I want to encourage you to produce another video about quantum gravity where you also mention which theory you like best. Best regards, Manfred Fuersich

[@badhombre4942]

They obviously meant explaining it to a 6 yr old Einstein.

[@sleethmitchell]

'understanding' something is perhaps the biggest myth of physics.

[@brianarodriguez2090]

This comment goes so hard

[@zyansheep]

The word "understanding" is kinda just a disguised query for a bunch of different things that are expected of people who "understand" a concept to be able to do with the concept, i.e. explain it, apply it, draw parallels to other concepts... like for many (most) words the true underlying reality is messy and complicated, the word just represents a pattern our brains abstract that reality into for convenience. Now _thats_ the real myth!

[@engineeringdisillusion]

Except Feynman spent most of his time warning us that if understand something on paper because you're not smart enough or you've not spend enough time on it or you're not seeing it in the proper way and end up thinking like "come on, it is really complex, who can REALLY understand this? but i can manage the equations and say the right words, therefore it's ok" akin to a philosophical zombie, you're only fooling yourself.

[@kindlin]

Understanding buoyancy is easy, do you sink or float? Do you weight more or less than the water you can displace? It's a problem any child has asked and anybody after a couple years of school should be able to solve, assuming the boat is a rectangle or you just know the displacement. But there is so much more you could know: how the forces balance, hydrostatics, what is the force of the water made of, what is the force of gravity, what if you vary any or all of these in either space or time? Once you start asking these questions, you are now beginning to truly understand that topic.

[@bryandraughn9830]

I'm so embarrassed. I used to think I understood some of this stuff. Frank Wilczeck wrote a book titled "Longing for the Harmonies" and I read it over and over and over until I was able to grasp his explanations. Now I realize he was explaining only the most basic notions of his field. He's a really good explainer. I'm just not a very good understander. Love the video!

[@OceanusHelios]

17:03 "It's all electrons, babe." Oh be still! My beating heart! You're speaking my love language.

[@snarkyboojum]

The deadpan humour is awesome. Thank you for your contribution of good content on KZbin :D

[@Buttons841]

In this video, I learned that without gluons my Elmer's glue wouldn't work.

[@AdrianColley]

I mean yes.

[@xponen]

Elmer's glue using photon (QED), while atomic nucleus using gluon (QCD).

[@yarondavidson6434]

Quite the opposite. Without gluons there won't be even a single material that your Elmer's glue (in the theoretical case you could get any) would fail to work on.

[@UnionYes1021]

Wow, you really give me hope! I’m a 66 year old retired woman and that you understand all this so well makes me happy. Thank goodness there is someone who understands this so well. Thank you.

[@jell0goeswiggle]

"I am not a professional science communicator" says PhD with 150k+ subscribers on a KZbin channel where she mostly communicates science. Jokes aside, love your content. Looking forward to finding out why my understanding of QCD is wrong. It's the one I thought I knew pretty well! Although I'm sitting here now wondering if anti-red and cyan are the same thing, so maybe not. Update: I'm not sure what I understand anymore, except this: to the chagrin of pure mathematians everywhere, Monte Carlo wins again.

[@Hyraethian]

Thank you for explaining why I don't understand QCD except in a vague, limited, fragmented, intuitive way. I appreciate the jargon tossed in at the end. All in all I've learned something, had a few laughs, and at least have enough information to keep asking questions.

[@DKonigsbach]

General Relativity and the Equivalence Principle - extremely complex. Einstein's "happiest thought": "A man in a falling elevator does not feel his own weight." - pretty intuitive. At the core of most complicated things is a core concept. It doesn't provide the essential details, but it is the concept that all of the details hang off of. I believe Einstein was expressing that If you are so caught up in the details that you don't recognize the core concepts, then you don't truly understand the topic. The true test is whether you can explain the core concepts clearly and simply.

[@aperiodicwalk3009]

Appreciate the space between "8" and your exclamation mark when counting the number of gluon types in your table. Not leaving any ammunition for these factorial jokers 😆

[@jiffylou98]

I think we over-emphasize the empirical aspect of particle theory, where we can't find when beta decay will happen, etc. and not that it's a probability distribution. Yes those mean the same thing, but it's a nitpick. I feel its more sufficient to my brain to say "we know that there's a 10% chance of an electron being 30 angstroms away from a point" than "we cannot actually find this electron"

[@cattnipps]

I like that clarification, thank you :)

[@3tp]

Float like a butterfly, sting like a bee. -Allen Einstein

[@MrAzulmagia]

"I don't fear the man that solved a thousand different equations, I fear the man that solved the same equation a thousand times." - Albert Eistein

[@Frahamen]

Sexy, almost evil, talkin' bout butterflies in my head -Shifty Shellshock

[@wokeaf1242]

I think I understand that life the universe and everything is far more complex then I will ever totally comprehend and I’m okay with that. You do have a remarkable ability to explain complex topics and leaving one feeling they came away with a lot. That’s real a cool ability I wish I had.😊

[@BentArrowni]

Angela just explained to me that QCD is a videogame where you have to train for years to get the basic controls down and the computer does all the playing but you recover the loot after tons of missions

[@KB-rj3jn]

This feels like, in molecular biology, going from understanding how certain proteins interact with other proteins or genes to developmental biology where you suddenly have 20,000-25,000 (ish for a eukaryote) points that all can be modified in many ways and exist in specific places at specific times. You can't really have an analytical explanation of multicellular development for now and im glad other stem people have similar struggles lol

[@n20games52]

If a 6-year old can't explain something to me, can I understand it?

[@GrantWaller.-hf6jn]

A good way to find out what they know.

[@n20games52]

@@GrantWaller.-hf6jn Ha! Yes!

[@dendendelen855]

One thing that bothers me just a bit, Feynman diagrams are not only used in the path integral formulation - like, you use Feynman rules all the time even if you are exclusively doing canonical quantization

[@DanPFS]

Ironically I did learn more from this 37 minute video about QCD/the strong interaction than I did in my grad particle physics course.

[@shelterit]

You claim not to be a professional science communicator? I can tell your that you're the fucking BEST one!!!!! Holy crap, I've struggled with this analytical Vs. numerical parts of math my whole life, and never understood why all the big names couldn't make sense of QM for me. I thought I was just thick, only suited to philosophy. And here you are, finally!!! just talking through it with charm and a lovely human touch, and I get it! I get it now! I mean, not QCD, I don't get the details of how it works, but I now finally get the relations and complexities involved. You have no idea just how happy and grateful I feel right now, thank you! ❤ You've not only explained QED Vs. QCD, but how relativity fits in, Feynman diagrams (and the dimensionality limitations of them), prediction in math and its relation to projection Vs. reality ... I mean, gosh, this was nothing short of THE BEST VIDEO ON THE INTERNET!!!!!!!

[@HarryNicNicholas]

i've been a carer for schizophrenia for around ten years, i don't have any formal qualification other than a certificate that says i've done a carers course, but one thing i learned even before the course is that when someone is hallucinating saying "you're imagining things" results in a very bad day. anyway. i treat all people as if they are mentally ill, i find that most people have hard time understanding how to tie shoelaces, never mind einstein. so in order to get your point across and have it actually register in someone else's brain, you have to put things in the simplest terms - that, say, a six year old can grasp. cos most people are six year olds, mentally. including me.

[@mateostenberg]

"I treat all people as if they are mentally ill" if most people had a hard time trying their shoes, maybe your point of reference for mental illness is skewed? I get hyperbole but it's just kind of a weird thing to say

[@3tp]

Why do we fall down, Master Bruce? To learn to pick ourselves back up. -Albert Eyestine

[@mdod0]

16:37 "Every single thing you know and touch and love can be described with qed" Put that on a T-Shirt and sell it please.

[@steffenbendel6031]

But I love gravity - that keeps me grounded.

[@kingduckfilms]

Yes! Also "it's all electrons babe"

[@hedgehog3180]

I'm going to show up with my “The cool stuff is actually all organic chemistry” t-shirt and start an argument.

[@AdrianColley]

There's also caesium-133 but it doesn't meet the "love" criterion.

[@kindlin]

Also... _is mostly described with_

[@robertarmstrong3024]

A 71 yr old thanks you. I finally understand QCD.

[@quarkonium3795]

I worked for a few months on research which related to QCD (hence my username and PFP). I definitely don't understand everything about QCD myself but I don't think I could ever explain it either. The summary version of the explanation I give for why I can't satisfactorily explain QCD is just "The math is mathing too hard". A good example is from my research. I was studying the dissociation of particles within cold nuclear matter which involves a lot of QCD interactions. In a normal electrodynamic interaction where the nucleus is considered a neutral mass, the equations are fairly straightforward and it's easy to picture a model of how each element within the system interacts with the others. Sure, the solution may involve either solving a nasty differential equation or brute forcing with a computer but the equations themselves are pretty easy to understand. In QCD the equations for interactions are just impossible to intuitively understand. One of the parts of my research involved looking for other research in theory and then putting all the component parts into a program to model the system I was studying. One of these components was five separate polynomials in multiple variables, the smallest of which involved 17 terms and the largest involved over 60 terms. It was massive and I had to copy the polynomials term by term into FORTRAN. There's no way I could visualize a model for a polynomial in multiple terms with a degree in the teens so how could I possibly explain what my model was outputting properly to anyone but an expert?

[@אניבאמתיהודי]

I am studying chemistry. The moment you said "field theory" i was like: "Nope. I have no clue what those are, and if i find out i'll be stuck modeling molecules for the rest of my life. Byeeeee!!"

[@gwensmosh5532]

that really is a feeling when learning about stuff in your field of study. You don't want to learn too much about something or you'll get hired to work with/study it! In urban planning, I've ignored some friends warnings against studying GIS.

[@РайанКупер-э4о]

You definitely did reminded me of the book called «Thinking physics». It's not for 6 yo, it's for middle schoolers, but it starts with integrals and ends with quantum theory, and all of that with actual physics problems explained in a way middle schooler would be able to do them. The book is wonderful introduction to physics for younger teens, you could learn it in your 5th year of school.

[@idontwantahandlethough]

1. cool glasses 2. great video yo 3. "Be the change you wish to see in the world" -- 50 Cent

[@ictogon]

Thank you 50 Cent

[@GoldenMinotaur]

"I'm gonna explain why I can't explain it" My favorite kind of video

[@Alex.The.Lionnnnn]

This quote definitely guided me as a primary school teacher. There's genuine substance to it.

[@bethlong7115]

Why is it that we’re always taught that Feynman diagrams should have time going upwards but when we actually use Feynman diagrams time is always going across?

[@hayuseen6683]

Maybe because we don't read or write bottom to top, so we turn it to the side to make a linear sense of progression of the statements

[@hhubschle]

Nice play with the spooky color balance in the video. Echoes the daunting weirdness of QCD.

[@Palozon]

You know we're the worst when we all come down here immediately to make up a bullshit quote only to see a million people have beat us to it.

[@tylerm.8684]

-Albert Einstein