But why would light "slow down"? | Optics puzzles 3

[@Rubrickety]

Part of what makes Grant such a superlative educator is how he treats the things he leaves out or simplifies. He always points them out, explains why he's skipping over them, and provides a hint as to what including them would look like. It's never "It's too complicated, just don't worry about it."

[@Dudeguymansir]

“The solution is trivial” Is it, though?

[@berryesseen]

That's what true mathematicians do. If they are lazy or out of space (or time), they always explain what a non-lazy person should do. They give kind of a recipe even though they don't write down the calculations explicitly. Physics people are in general more lazy to explain what they simplify and why they simplify.

[@VeganSemihCyprus33]

To understand, study... To live in peace, watch this 👉The Connections (2021) [short documentary]💖

[@samueldeandrade8535]

Superlative educator? More like overrated af.

[@samueldeandrade8535]

​​@@berryesseen "Mathematics is being lazy. Mathematics is letting the principles do the work for you so that you do not have to do the work for yourself" - George Pólya

[@andycgn1991]

If there was a Nobel Prize for explanations, you would be my canditate. Thank you for taking the trouble to explain things so profoundly and vividly. You are my hero.

[@JuliusUnique]

and where is mine for not being native english, having a rough childhood, getting love scammed and not being able to find a wife? His videos are good, but the effort we both put in life is probably at least equal so I deserve the same price. Thanks for calling me a hero since it counts for me too

[@danguee1]

@@JuliusUnique I had that - have this Nobel Prize from me:🥑

[@JuliusUnique]

@@danguee1 thanks

[@julianklimke3476]

@@JuliusUniquewhat is your point?

[@JuliusUnique]

@@julianklimke3476 oh wow, I made my point very clear, maybe you should work on your english

[@claudiooton1732]

I teach optics in the University, and I can say that you nailed this one, really the best explanation I've ever seen on the matter. I'm sure Feynman would hug you if he could see this video.

[@3blue1brown]

Thanks! If you have any other optics puzzles you use with your students, do feel free to pass them along.

[@PluetoeInc.]

After reading Mr. feynman's self-authored biography , I feel I have a little virtual model of his consciousness inside my mind and it's saying Thank you grant , Thanks for respecting the height of the standard of self-inquiry and discovery that I so deeply believe in and tried instilling in everyone I shared a piece of my mind with .

[@baptistedelplanque8859]

⁠​⁠​⁠​⁠@@3blue1brownwell, you have the base to explain many phenomenons. Maybe you can use it to introduce cool things to viewers: linking chemistry to different oscillators = spectroscopy. Or even going non linear. Surface interactions also has some nice effects like Goos-Hänchen... Well that might be quite niche.

[@JuliusUnique]

thanks, Feynman hugging me is a nice thing to hear, I don't get much love so I appreciate the compliment. While I didnt make this video, I'd have done it if I had the resources to do so, and I put a lot of effort into improving humanity. It's rough working hard and getting no appreciation for it

[@GooogleGoglee]

Can someone explain to me why describing the wave in that way as cos(wt) would not let increase the "cycles" (see also frequency) of the wave so described because of 't'? (Which is in the argument of the function cos()... After all 't' is not a constant and will increase... So what am I not seeing here?

[@rectorsquid]

I have always regretted my lack of math education. The equations in the video barely make sense - the algebra makes sense but the differential equation stuff is a language I just don't speak - so seeing the visuals to explain these things make them accessible to me. Thanks. And those visuals are absolutely stunning!

[@tillorrly1128]

Differential equation is the place where there be dragons in maths. I think only a small subset of them can be solved beautifully, while most are basically brute forced by guessing the solutions and the checking if that guess actually solves it.

[@domenicobianchi8]

understanding basic differential equation self thought is possible. find a good book, with 50 hours you can master them.

[@Kingbimmy]

Same. I had the misfortune of having most of my math and science teachers not caring to actually teach anything, and a majority of them didn’t speak English well enough to give me the basics. I failed PRE calculus 3 times in a row 😭 I feel so betrayed. My favorite thing in the world is science and I want so badly to study things like astrophysics but there’s so much basic stuff I’d have to go back to 💀😔💔 This video was wonderful though because I didn’t necessarily have to know everything to get the idea! I’m glad I found this channel.

[@incognitoburrito6020]

​@@domenicobianchi8 Very few people have the time or willingness to spend 50 hours teaching themselves differential equations out of a textbook. Same way most of us aren't willing to take up small-scale wheat farming just to be a little more connected to our toast

[@greegorygrimlee5487]

​@@incognitoburrito6020I guess he aint talking to you then 😂 For others who are lamenting not having mastered differentiation, 50 hours is about what people spend each month on social media and wandering the internet these days, and the learning is free, so definitely more achievable than a wheat farm.

[@lakshya2441]

this is the clearest explanation I ever heard. It's like 15 optics lectures condensed in a single video. Absolutely mind blowing...

[@TM_Makeover]

True that

[@atticuswalker]

I have a simpler explanation. time slows down in glass. that's why green Lazers look red in glass.

[@MadScientist267]

Yeah just use the right terms... Phase SHIFT

[@VeganSemihCyprus33]

To understand, study... To live in peace, watch this 👉The Connections (2021) [short documentary]💖

[@HilbertXVI]

​@@MadScientist267??? It's pretty common terminology lol

[@a11aaa11a]

I always wondered what Feynman's lectures would have been like if he taught them with today's technology, and man this is it. The world is going to have some brilliant physicists and mathematicians thanks to you.

[@joshyoung1440]

You've always wondered what his lectures would be like... so you see a particularly good lecture and say "this is it, this is what they must have been like, they must have been great because Feynman was great"?? If I were a hack this is where I'd say that Feynman would cringe at that assumption, but I won't, because _I never fuckin' met the guy_

[@a11aaa11a]

@@joshyoung1440 I have no idea what your comment means

[@insertcreativenamehere492]

@@joshyoung1440 learn to read

[@BassilioDahlan]

@@joshyoung1440 You might have missed it but Grant mentioned in the beginning that his presented explanation is based on Feynman's lectures

[@DrDeuteron]

@@joshyoung1440I did meet him, I was in his last lecture, and I can read, and I have no idea what your point is.

[@tahsinshafin100]

I'm genuinely telling you Grant, for all the human beings seeking the absolute deepness of reality asking every bit of "Why", *you are an unprecedented blessing.*

[@samueldeandrade8535]

People sure like to suck this guy's b@lls. It's impressive.

[@roseghould]

cosign

[@anonymous_4276]

Agreed 100%, the question of why would frustrate my endlessly in school.

[@abrahanpinedo]

You are Goddamn right!

[@vigilantcosmicpenguin8721]

Grant must get along great with four-year-old kids. Every time they respond to something with "Why?" he'll always have an answer.

[@abrahanpinedo]

This video reminded me of a talk I had with some friends at CERN, where I told them that we didn't really understand why light refracts, the typical explanations weren't enough. When I looked into it myself, I remember reading the response in the Feynman Lectures and being more or less pleased with what it said. But now with the video and animations everything clicked! From a question I had asked myself ten years ago, it is an incredible sensation! Thank you Grant.

[@paparapiropip87]

After a double major in math and physics, I'm doing a PhD in physics. A great part of it deals with light-matter interaction. I must say this is a beautiful representation of a phenomenon that most of the time physicists "sort of" imagine. Thanks for such a great way of visualizing physics! And thanks for giving our dear harmonic oscillator the visibility it deserves!

[@runakovacs4759]

Spectroscopy for life!

[@onradioactivewaves]

🤭 sounds like a great deal of it is a Snell's pace of life

[@davidrandell2224]

“The Final Theory: Rethinking Our Scientific Legacy “, Mark McCutcheon for proper physics.

[@atticuswalker]

can you explain why green Lazer light looks red inside glass. and the white light dosent seperate into colors until it leaves the glass at a different angle than it entered. why everyone agrees light slows down in glass but nobody will consider time moves slower , as the reason.

[@newuser689]

​@@davidrandell2224 quackery lol. if he was smarter than einstein, hawking, newton like he implies then literally everyone would recognize him. but nope, Some Guy (tm) figured out the hardest theory in the universe.

[@NiMareQ]

I don't think there is a material on youtube or the internet explaining this stuff in such detail and so comprehensibly. I am blown away. It instantly clicks!

[@tirterra1222]

I was genuinely thinking about working on prisms an hour ago as an electromagnetism exercise, this is too perfect to be true.

[@vitaminncpp]

Me at 12.15 AM: this is enough for today, let's sleep. 3blue1brown after 15 seconds: this is perfect time to upload new video. Me : okay, this is last one😂😂.

[@_John_P]

Probably there's an educational video on youtube for any subject you can think of, and you're probably subscribed to most subjects you study, or are interested in. So, chances are that eventually a video will pop up, matching your latest need.

[@goldnutter412]

😂🥲

[@goldnutter412]

33 minutes ago@@_John_P 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 minutes ago erm okay youtube whatever But video 45mins ago comment 33 minutes ago hmmm yes not timing at all was just the algo Classic 1 | 0 thinking

[@waelfadlallah8939]

I am waiting for barber pole effect part 3 pleasssssssssse!

[@squidsword0]

Being able to boil down complicated phenomena to the bone this elegantly... None of us would have ever developed the background to absorb this without your help. You’ve gifted so many people the fascination of understanding how reality works

[@jainalabedin440]

well said comrade

[@laxminarayanbhandari855]

"so, everything was just a harmonic oscillator?" "always has been." Great video as always. Waiting for the next part!

[@siddhapandeypanigrahi353]

A man of culture 🗿

[@DrDeuteron]

Simple, damped, driven, coupled …and then quantized Ftw. Pendulum with large amplitude: Hold my 🍺

[@laxminarayanbhandari855]

@@DrDeuteron lmao. small angles ❤️

[@jakeadams2562]

13 minutes in and you’ve already granted 3 revelations in my understanding of our world that would have otherwise taken years for me to understand… you have a very special talent and I thank you massively.

[@HuygensOptics]

The animations in this video are clarifying so many details that are very hard to explain in any other way. Fantastic, I loved every second of it!

[@Arnogorter]

This video complements your recent one very well!! Both are fantastic videos.

[@helmutalexanderrubiowilson6835]

I am 42 years old I have been stuyding electromagnetic waves for 20 years and teaching Wireless and optical applications for around 12 years. I feel safe to say that you are one of best - if not the best professor of the planet. The The amount of work you put in your explanations is unprecedented.. as you show in your videos there are some excellent professors around there but none of them with the skills to represent the content in this way. Thank you I'm fan of you great work!! I think you should publish some books using your skills explainning the topics you present here... They would be global betsellers for sure.

[@Anjihyu]

The single best channel on this entire site. I wish I had money to spare, because you, mister, deserve it more than anyone. Brilliant video, brilliant editing, brilliant visuals, brilliant explanation.

[@DiaryOfAGhost_StreetsOfTempe]

You seriously need an award for your ability to teach. It's never about the information for me but how it is explained and in what tone. I hope you love your job. Because I for one appreciate the output. Thank you 😊

[@xminty77]

22:11 my favorite 3b1b moment thank you Grant for your works it has been monumental to my studies

[@AstroMattWood]

I teach a university course in Waves/Acoustics/Optics, and this video is now assigned viewing. Amazingly well done - thank you.

[@tHaTsWhAtI.mSaYiNg]

This may be one of the first 3b1b videos I actually understood, wonderful job. Also it is kind of adorable thinking that Grant approached his niece like 'can I push you in a swing for a math video, but like, really badly'

[@DellHell1]

A twenty minute video gives me more intuition than two years of studying field theory at university. As an undergraduate I would not have been able to follow the Feynman lectures as you have done. Thanks for these really very important video lessons.

[@DrDeuteron]

Omg, grant should get paid to do a complete animation of the Feynman lectures.

[@adjsmith]

As an undergraduate, I would have loved these videos. (As a graduate student, I still love them!) They make so much sense. Your explanation of the sum of sine waves was excellent.

[@AlphaPhoenixChannel]

This might be my favorite physics explainer video ever, and it's on a math channel - undergrad me would be twitching =D I love this video because the animations of the phase shift and the oscillator so succinctly get the point across when it normally takes (or at least for me it took) years of imagining and trying to extrapolate from static images on a whiteboard and a lot of conflicting explanations. It's very easy to grasp small pieces of it but if you learn too many disconnected pieces that use different assumptions and approximations you end up with really pretty puzzle pieces that don't fit together. I really hope that others had the same reaction as I did - when I publish something I'm always afraid that it will only make sense to me just because I already know the material, and I think this style fights that very effectively. I'm very excited to see your explanation of "metamaterial" indeces of refraction because the explanation of why speed is bending that I know (plane waves on a 2d mesh are like your tank treads) shouldn't work with speeds faster than C. If it's a phase vs group thing I'm getting ready to be confused but I'll probably understand it better than I ever have before! wait a minute - as I type this I might be having a lightbulb - you showed the startup transient - nobody ever shows the startup transient. is that how you obey relativity but have a phase velocity >C? ahhh that would only work near resonance, which those funky capacitor loops on paper DO. oh my god. EVERYTHING IS SPRINGS 😁

[@ski3r3n]

woah

[@estrheagen4160]

This is probably your best work so far. To explain third-year undergraduate physics in such a clear and approachable manner is nothing short of genius. This is why the Feynman lectures are beloved by students, often being a student's main literature despite only being supplementary literature in the course plan. I first heard the spring analogy in the context of the Dulong-Petit law. Each quadratic degree of freedom contributes kT/2 energy per particle (equipartition theorem); A particle in a crystal can be approximated as having six quadratic degrees of freedom: three kinetic (v_x, v_y, v_z) and three translational (x, y, z) because it's "sprung" to its nearest neighbours in all three dimensions; therefore, a crystal should have a heat capacity of 3 k per particle, or 3 R/mol. And, yeah crystal heat capacities do cluster around 3R/mol. Simple but damn good approximation.

[@Elfstones3n1]

As a former math & science teacher, this video is one of my favorites ever! Some parts were intuitive; other parts weren't; other parts I was figuring out a minute before you addressed them; all of it was SO INTERESTING!!! (Also, I loved the illustration with you pushing your niece on the swing!)

[@JoelFishel]

This is just utterly phenomenal. I can't believe the level of deepness in explanations that we're able to get for free on the internet living in today's world. Your videos are going to truly change the world as a new generation will learn concepts with so much more clarity than generations before. I'm just in awe.

[@EletronicaCaseira]

This video is awesome in so many ways. The amount of intuition provided is really valuable. It is really difficult to imagine getting the same kind of information in a lecture or in an article. Many of the concepts that seemed common sense or well-known simply receive another level of comprehension in a video like this and after that life gets a little bit more beautiful. Summary: Thank you very much!

[@alessandrolodi8951]

Cannot stress enough how inspiring this guy and his team are. True modern scientist

[@pitCest]

And artist I must say. It's a form of art this way of communicating

[@VeganSemihCyprus33]

To understand, study... To live in peace, watch this 👉The Connections (2021) [short documentary]💖

[@berryesseen]

To be fair, I wouldn't say this goes under the name of science. It's more like an educational videos. He's a teacher right now. Don't get me wrong. By definition of his PhD, he was a scientist. Today, he has a different career path, which is very very inspiring. But in the end, it's teaching. Just in case of a misunderstanding, I admire his work a lot. And this channel is one of my top 5 among all KZbin.

[@piman7319]

Not actually a PhD. He calls himself a (math) explainer@@berryesseen

[@luckyw4ss4bi]

The animation at 7:30 is truly astounding and enlightening! It'll forever change the way I think about light passing through a medium.

[@minhhieuao5768]

Love your animation, please never stop doing this🙏

[@Pidrittel]

As a physicist, I (should) already know all of this. An I would argue I mostly fo do, but often in a much more abstract and thus less intuitive way. And because of that, it would be a lie to say I did not learn anything from this. Very well done! Those animations are just pure gold, and the fact that you apply your nitpicky maths brain to physics questions and your reasoning why certain things "are" really is a big win for any physicist watching!

[@godoit7569]

Hey, i am an aspiring physisict. An 18y/o, In Senior high school. Physics gonna be fun by thinking that what we will do to it and 😢 also what will it do to us. Though, nice.

[@Beny123]

Your nitpicky maths brain 😢 . Indeed it is

[@stylis666]

It's the cross over I never even expected in my wildest dreams. 3Blue1Brown explaining physics

[@ifyhu92]

This video series were so enlightening for me and took away so much confusion. I really like your style of asking why all the time. At university when I keep asking why people treat me weird and they say that is just what it is. But you explain everything very well. And you teach very well. The visuals are out of this world!! This is amazing. Please make more physics videos! I love you!!!!!

[@AdityaPatwardhanJ]

Dear Grant Sanderson, You turn raw mathematics into an intuitive knowledge, helping us evole our own ideas about the physical works, with so many emergant subject to explore. You turn math into a real world experience, much like our brains must be doing when it takes measurements of this strange place around us. Thank you for the profound wisdom you share in the simplest of ways. Hats off to you, Sir! Always a fan, best regards :)

[@cegalleta]

Props to you for explaining topics proper of a electrodynamics/solid state physics class to a wide audience without making it confusing or hard to digest

[@leokyle6195]

3b1b, I gotta be giving you great thanks. I've ended up pretty much of a humanities guy mostly in my research and education life but deeply believe that the life of the mind requires all directions of enquiry and that therefore the stem/humanities distinction is always and forever something to work on both sides of. Your videos are incredibly good at explaining this fundamental stuff to even a no-attention-span fool such as myself and I will ever be grateful for these insights. All my thanx p.s. your lockdown math videos were awesome and helped keep my mind rigorous during lockdown xoxo

[@lousi47]

You are the best , people always find it ridiculous when I ask them « why » for everything and often answer « this is just the way it is » whereas you explain every single details , this is why you really are the best !😁thank you

[@GroovingPict]

You will probably like the update they did to the Dark Side cover for the 20th anniversary edition in 1993 then, where they made it more realistic, with the spectrum being just that: a continuous spectrum rather than individual colours (which btw is also missing a colour compared to the more common colour representation). They even included a faint reflection of the incoming beam bouncing off the surface of the prism.

[@gamingagent80]

What you said at 3:39 is EXACTLY what I feel like when I don't understand something to its full extent and why it frustrates me that as a high school freshman, so much of physics is just so far out of my reach I would love it if someone could teach me exactly how it works. And I would like to appreciate that you are that person for me, even if I can't just ask you simething like I could a teacher.

[@borisjoukov]

👏👏👏 Beautiful, as always! I love how you manage to touch on so many crucial physics and math topics in a single video!

[@waelfadlallah8939]

I am waiting for barber pole effect part 3 pleasssssssssse!

[@MadScientist267]

I like his stuff usually but this is *horrible* on many levels. I suspect it's in part that he's still dumbing it down too much or something but for example terms like "phase shift" elude. "Phase kick back"? Lol 🤦‍♂️ Edit: He uses the correct term later on... I don't know WTF the deal is but yeah... 🤷‍♂️

[@VeganSemihCyprus33]

To understand, study... To live in peace, watch this 👉The Connections (2021) [short documentary]💖

[@sploofmcsterra4786]

4:05, 9:01 As a Physics researcher, I'd say these are the best animated demonstrations of atomic dynamics leading to near and far field behaviour I've ever seen. It is very difficult to create good illustrations for electrodynamics, but sorely needed!

[@nathanaelhahn]

Grant, what you do is what I consider true mathematics to be. You're putting the wonder, exploration, and intuition back into what for many of us simply died when we saw our first variable. Truly an inspiration for any math teacher!

[@svmchop]

I have an undergrad in physics and a masters in engineering. Just watching your animation and listening to your soothing voice reminded me how much I loved learning about stuff. It almost made me cry tears of joy. Godspeed man..

[@gustavinho1510]

Thanks Grant, you have made my thursday by releasing this video. I was so intrigued by your past two videos and couldn’t wait for this one, truly a beautiful way to visualise electromagnetic waves and optics.

[@moltenguava9418]

I've been watching your videos for around 5 years. They inspired me to pursue my major. I have now graduated. I rarely see channels continue to make such good content consistently for over half a decade. Thank you.

[@santig0_]

0:50 "hit a wall"... talking about pink floyd... what a awsome choice of words

[@sirmr6597]

I absolutely appreciate this. I’m always asking questions that seem to be never answered. The way you are aware of these questions and also are ready to readjust what questions we should ask is absolutely invaluable.

[@9darkspells]

This along side the recent videos by Huygens Optics have added so much to my understanding of wave propagation

[@PulseCodeMusic]

Excellent job. I've seen a few people have a go at this explanation and no one came close to the clarity or thoroughness of this.

[@cookieslammer6411]

I can't even explain the amount of joy that I experienced watching this video... Grant, as a third-year physics student I want to tell you, that you job is more than brilliant. Your lessons yet helped me to get through many difficulties on my academic journey. I dream of becoming a physics teacher one day, and your approach to teaching is my main source of inspiration. Respectfully, I bow low to you, Mr. Grant.

[@messiah52]

Thank you very much, you helping me to understand the school curriculum (11th grade in Russia) much more deeply, everything is very clear and detailed, I can't even imagine how much time is spent on these visualisations... ❤️

[@hurshasnarayan]

One day your niece will grow up to realise she has an uncle who's a genius. I wish we had educators like you and the tools that we have now when I was a student. Having a background in NVH and currently working on control systems this video was very exciting for me. Thank you. 🙏🏽

[@atil4]

A lot of physics and math Extremely well explained, and compressed in 29m. Please more!

[@user-rm2qj2jh4l]

Yay! I've been looking forward to this one! I've been confused about light for a while and I think this video will help me understand!

[@waelfadlallah8939]

I am waiting for barber pole effect part 3 pleasssssssssse!

[@atticuswalker]

finding an excuse you can believe isn't the same as understanding the reason.

[@MadScientist267]

This is way overcomplicated and oversimplified all at the same time. What happens isn't super intuitive but it isn't really that hard to understand either, but not when the explanation is a series of weird rabbit holes.

[@VeganSemihCyprus33]

To understand, study... To live in peace, watch this 👉The Connections (2021) [short documentary]💖

[@beemerwt4185]

6-ish months ago, I had to learn a lot of this because I was working on a game, and the math about waves hit me... like a wave... as it's all coming back to me. I like the way you explain it, especially with the vector visualization. Picturing this in my head I use the words but actually seeing you graph a vector was fascinating. A lot of the math I know nowadays from programming videogames comes from my AP High School classes, but we never touched on vectors so I have since taught myself. I guess that was more of a Linear Algebra thing (which wasn't offered at my school), rather than Calculus and Trigonometry (which is what I took).

[@landonkryger]

I look forward to your video about the index of refraction being < 1. I hope you also cover the rare case where the index of refraction is negative.

[@fdert]

You just earned yourself a new subscriber. I'm very impressed with how you explained the additions of waves with use of vectors, by far the best explaination of this phenomenon I've seen yet.

[@suddhasattasaha4793]

I could truly appreciate the real beauty of physics after watching this video. It takes a lot of hard work to produce such beautiful, detailed and asthetically clean and smooth animations to depict hard to imagine pictures which we are required to visualize to understand physics and dive into the thorough depths of it. Wonderful.

[@TheWinWinWorld]

I've never in my life (!) seen a more brilliant explanation. While physics laid out by You mesmerized my mind completely, Your comment with the swing "this isn't how MOM does it..." just stole my heart for the power of intuitive explanation of the MATER as if in a primary design of some kind. Thank you and please don't stop making such great videos.

[@Codexionyx101]

People like to say that light slows down in a medium because it "bounces off" the particles in the medium. Kyle Hill refuted that in one of his videos, but didn't really describe exactly what's happening. This finally explains what he was talking about.

[@OmarOmar-sk5vu]

I am forced to thank you!! I do love colors and general understanding of science to enjoy and appreciate what's going around me, but after such a detailed, amazing clarification, science feels more enjoyable than what it used to be while I was in Uni. I really wish you a success in the field and for a greater impact on students/ knowledge seeker life. Respect!

[@WarzoneMasters]

i learned so so much with your videos respect forever ♾️

[@waelfadlallah8939]

I am waiting for barber pole effect part 3 pleasssssssssse!

[@johnbrz]

The greatest video lecturer in the world-plain and simple.

[@lazarussevy2777]

Good timing! I'm going into optics in my physics class just about now!

[@deneshk353]

One of the best 30min spent! probably the cleanest and neatest to the point explanation! Thank @3Blue1Brown for doing this...

[@srroome]

never laughed so much at one of your videos as at "bad at pushing a child on a swing". Yeah, that's extra special wrong. The effort you put into these is incredible, thank you so much for what you do.

[@bhumigandhi2426]

I just love the visuals and his explanation as even a 9th grader like me who couldn't do any of the math in this vid still understood each of the topic and had many questions in common with other viewers. I just love this channel sm

[@Youtubehastoomanyads]

Hey! You are the reason I love maths so much thank you, for such amazing videos.

[@waelfadlallah8939]

I am waiting for barber pole effect part 3 pleasssssssssse!

[@gw6667]

*math

[@iqwit]

​@@gw6667not everyone is American my guy

[@raianaratti9943]

I watched float head physics' video on this and he explained the "kicking back a phase" thing really, really well if anyone wants an intuition on why that happened. This video really helped me understand the concept floatheadphysics was not able to do that well in the last part of the video which is the "bad at swinging the child" analogy, thank you to both these amazing channels for making these videos

[@FoughtAgaisntSisera]

This video is amazing! I wonder if you might touch on Hamiltonian physics applied to ray optics and how that connects to the principles described here

[@PlayNowWorkLater]

This channel never disappoints. Love the accessibility of this content. I’m a musician, never studied science or math past high school. Yet this, what I’m assuming is university level math and physics makes complete sense. Wish I had teachers like this back in high school

[@sstidman]

Kudos to that poor baby girl for enduring her uncle's weird experiments.

[@Dave.A.R]

This video and the explanations given by Fermilab's Dr. Don are the clearest to understand. The standard explanation always felt like "you just say you understand it".

[@berryesseen]

I hope that no kid was harmed in the making of this video. From the perspective of an electrical engineer, this video was super interesting and explanatory. It's much easier to understand waves and frequencies in this way.

[@TreeTrunks-de5wn]

Man I’ve been watching your videos for a long time (since SoME1) but god damn this is the most beautiful video you’ve ever created. I’m only 12 minutes in and my jaw has been dropped several times already. Thank you for creating this masterpiece! You rock!

[@jari-0815]

22:23: thats why "mom" can't teach you about prisms

[@lulaklaw4101]

no one ever told me light was just a LITERAL wave from things moving! i always thought light was like... a particle that moved in a wave formation. this video is awesome.

[@890sigma]

Love the vid! Could you also cover Maxwell’s equations in a video?

[@gw6667]

This is not an intro to electricity and magnetism class. Plenty of resources on KZbin to dive in. What do you want him to do, derived the equations?

[@890sigma]

​@@gw6667I just want a video that shows the visual intuition behind maxwell's equations in a way that feels intuitive and makes sense

[@GaussianEntity]

​​@@890sigmaThe four equations are basically the four main laws of electromagnetism. The propagations described in this video is one of them, Faraday's law of induction. You may find visual representations if you search for them separately.

[@davidtoomey1400]

I watch so many KZbin channels that explain science and math. They do a great job conceptually, but 3Blue1Brown is the only one that is able to effectively bridge the conceptual intuition with the formulaic abstractions. Allowing you to absorb the fancy notation into deep understanding. Thank you for your work.

[@Inserthandle-ff6jw]

In which chapters of the Feynman lectures is this given in? Thanks

[@Inserthandle-ff6jw]

Chapter 31: The origins of the refractive index

[@devinkillough9]

Grant is such a great teacher. I have always enjoyed learning, but with Grant there is always the audible “Ahhhhh, that checks out” when watching these vids. Keep it up!!!

[@VJfication]

Me gently murmuring: "that's not how my teacher explained things". 😂

[@dav1dsm1th]

It's insane that videos of this quality are available for, in effect, no cost to the viewer. Amazing. Thanks for taking the time to make and publish them.

[@experiment8924]

Anyone else here from The Action Lab?

[@skatethe4881]

YOU'RE FROM THE ACTION LAB?! Nah, we're here from the nothingness that lies beneath the everything.

[@YanivGorali]

This channel is a treasure that keeps on giving

[@RoyHoy]

I understood nothing

[@gabrielamaral978]

Then you have became god

[@luisfranciscocordero9627]

Man... You give the most compelling and easy to grasp explanations. Thank you so very much for the dedication in making every video. I'm a physician with a VERY poor math training background, and originally I found your channel when looking for Bayes Theorem explanations. You excel at every single topic. Congratulations and keep it up please!

[@nathanborak2172]

As an undergrad I was trying to think of ways to intuitively visualize what adding two waves would do, and came up with your rotating arrow argument. It also works well for visualizing beat frequencies. I felt like I had discovered an amazing secret when I thought of this and wondered why it wasn't commonly explained this way. This is true for a lot of your explanations, it feels as if you explain it the way it should have been explained all along. Of course, you still have to know how to do the straight computations, but intuition is important too.

[@bide2505]

22:25 Best part of the solution/puzzles 😊

[@jayakrushnasahoo4403]

INCREDIBLE. Finally got a satisfactory explanation after longtime wondering about it. Keep the curiosity alive, it will sustain the science and the civilization.

[@davidlinn8175]

I love you explanation why the index of refractions exists at all. I had never considered it this way despite learning it over and over again throughout school. The way it was explained to me when I was first learning quantum mechanics (because I had this exact question of why does light bend and slow down) was slightly more discrete. I was told to consider a quanta of light. Traveling through a perfect vacuum, the maximum energy is allowed because there is nothing to interact with. The moment it enters a medium, think of the path length of the particle of light. It interacts with silica and electrons and everything within the medium (in the case of glass) bouncing from one particle to another. The light is still moving at "c", but cannot take a direct path through the medium because of the EM effects interacting with the particle. This explanation definitely lacks an explanation of the bending effect, but is definitely how I have exclusively thought about it until now. Great explanation!

[@linearj2951]

Everything about this video was awesome, but the part that stood out to me was your characterization of "handed-down vs discovered." This is a great way to express my frustration with getting answers to some questions. I ask "Why/How" (discovery), but instead get "What" (handed-down). One question I have had forever like this is: why do mediums block waves with wavelengths shorter than the medium thickness? E.g., why does bass get through a wall, but treble is blocked? I always get the answer that "of course, because treble is higher frequency, and thus shorter wavelength. If shorter than the thickness, it is blocked." But... WHY? That is a handed-down answer; I want a discovery answer!

[@SC-rb2jr]

This video is shocking. It takes a difficult topic and with a calm clear explanation and superb graphics, it actually makes it understandable. This is the ultimate in education excellence. Please make these videos known to everyone that wants to learn about physics.

[@bastienbourdon]

16:01 This is so cool when you get to a clear breakthrough explanation like that!

[@jonahansen]

Dude - you do such an excellent job here. I created a playlist about index of refraction, and you cover it all, and with the correct and quantitative explanation for every aspect of it.

[@patrickmuller3248]

That is a FANTASTIC video. You give an explanation AND give further explanations to those. That is genius! One of the best ways to describe what is happening I have seen to date.

[@johnpapp131]

Don’t usually comment on KZbin but I’m in awe about how good this video is. I wish all physics and math concepts could have been explained to me in a was that is as intuitive and interesting as this video. Keep up the good work!

[@agwoml]

I have no idea as to what sin, cos and tan are since my school didnt bother to teach me. I know nothing about the electromagnetic field and most of the terminolgy here flies over my head. Yet you and your video manage to make me grasp it somewhat and instill a feeling of real discovery instead of just handed down info. Just like you have said. This is the third time i have watched this video and everytime i can understand and follow another part because of something else I've learned somewhere else. This video is a tracker of progress on my scientific journey just because of the sheer volume of quality information within it. I truly thank you.

[@ckimsey77]

Dude I love your videos....the engineering part of my brain hates incomplete explanations, and not only do you fully disect everything but also provide really good animations to bring it all together. You deserve some type of reward or metal or something...thank you for your time bro

[@afriendofafriend5766]

The best practical demonstration of light refraction is definitely the niece.