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

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  • Опубліковано 9 тра 2024
  • How the index of refraction arises, and why it depends on color.
    Quotebook Notebooks: 3b1b.co/store
    These lessons are primarily funded directly by viewers: 3b1b.co/support
    An equally valuable form of support is to simply share the videos.
    Looking Glass Universe videos on the index of refraction:
    • I don't know why light...
    Much of this video is based on the following Feynmann lecture
    www.feynmanlectures.caltech.e...
    The explanation for why the phase of a wave produced by a plane of oscillating charges is a quarter phase behind the wave of a charge in the center of that plane, and hence a quarter phase behind that of a light wave inducing the oscillations, is given in the previous chapter:
    www.feynmanlectures.caltech.e...
    Sections:
    0:00 - The standard explanation
    3:14 - The plan
    5:09 - Phase kicks
    8:25 - What causes light?
    13:20 - Adding waves
    16:40 - Modeling the charge oscillation
    20:59 - The driven harmonic oscillator
    26:57 - End notes
    Thanks to these viewers for their contributions to translations
    German: Ole
    Hebrew: Alon Altman, Omer Tuchfeld
    Hindi: Saurabh
    Portuguese: @doryhelioaires
    Urdu: Momini0
    ------------------
    These animations are largely made using a custom Python library, manim. See the FAQ comments here:
    3b1b.co/faq#manim
    github.com/3b1b/manim
    github.com/ManimCommunity/manim/
    All code for specific videos is visible here:
    github.com/3b1b/videos/
    The music is by Vincent Rubinetti.
    www.vincentrubinetti.com
    vincerubinetti.bandcamp.com/a...
    open.spotify.com/album/1dVyjw...
    ------------------
    3blue1brown is a channel about animating math, in all senses of the word animate. If you're reading the bottom of a video description, I'm guessing you're more interested than the average viewer in lessons here. It would mean a lot to me if you chose to stay up to date on new ones, either by subscribing here on UA-cam or otherwise following on whichever platform below you check most regularly.
    Mailing list: 3blue1brown.substack.com
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    Website: www.3blue1brown.com

КОМЕНТАРІ • 1,6 тис.

  • @Rubrickety
    @Rubrickety 5 місяців тому +2869

    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
      @Dudeguymansir 5 місяців тому +69

      “The solution is trivial”
      Is it, though?

    • @berryesseen
      @berryesseen 5 місяців тому +64

      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
      @VeganSemihCyprus33 5 місяців тому +2

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

    • @samueldeandrade8535
      @samueldeandrade8535 5 місяців тому +1

      Superlative educator? More like overrated af.

    • @samueldeandrade8535
      @samueldeandrade8535 5 місяців тому +9

      ​​@@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

  • @claudiooton1732
    @claudiooton1732 5 місяців тому +814

    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
      @3blue1brown  5 місяців тому +230

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

    • @PluetoeInc.
      @PluetoeInc. 5 місяців тому +47

      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
      @baptistedelplanque8859 5 місяців тому +9

      ⁠​⁠​⁠​⁠@@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
      @JuliusUnique 4 місяці тому +2

      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
      @GooogleGoglee 4 місяці тому

      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?

  • @andycgn1991
    @andycgn1991 5 місяців тому +543

    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
      @JuliusUnique 4 місяці тому +5

      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
      @danguee1 4 місяці тому +6

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

    • @JuliusUnique
      @JuliusUnique 4 місяці тому +1

      @@danguee1 thanks

    • @julianklimke3476
      @julianklimke3476 4 місяці тому +7

      @@JuliusUniquewhat is your point?

    • @JuliusUnique
      @JuliusUnique 4 місяці тому +1

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

  • @laxminarayanbhandari855
    @laxminarayanbhandari855 5 місяців тому +403

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

  • @lakshya2441
    @lakshya2441 5 місяців тому +809

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

    • @TM_Makeover
      @TM_Makeover 5 місяців тому +3

      True that

    • @atticuswalker
      @atticuswalker 5 місяців тому +8

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

    • @MadScientist267
      @MadScientist267 5 місяців тому +3

      Yeah just use the right terms...
      Phase SHIFT

    • @VeganSemihCyprus33
      @VeganSemihCyprus33 5 місяців тому

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

    • @HilbertXVI
      @HilbertXVI 5 місяців тому +6

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

  • @tahsinshafin100
    @tahsinshafin100 5 місяців тому +498

    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.*

    • @VeganSemihCyprus33
      @VeganSemihCyprus33 5 місяців тому +1

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

    • @samueldeandrade8535
      @samueldeandrade8535 5 місяців тому

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

    • @roseghould
      @roseghould 5 місяців тому

      cosign

    • @anonymous_4276
      @anonymous_4276 5 місяців тому +4

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

    • @abrahanpinedo
      @abrahanpinedo 5 місяців тому +1

      You are Goddamn right!

  • @a11aaa11a
    @a11aaa11a 4 місяці тому +90

    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
      @joshyoung1440 4 місяці тому

      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
      @a11aaa11a 4 місяці тому +6

      @@joshyoung1440 I have no idea what your comment means

    • @insertcreativenamehere492
      @insertcreativenamehere492 3 місяці тому

      @@joshyoung1440 learn to read

    • @BassilioDahlan
      @BassilioDahlan Місяць тому

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

  • @rectorsquid
    @rectorsquid 5 місяців тому +96

    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
      @tillorrly1128 4 місяці тому +6

      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
      @domenicobianchi8 4 місяці тому +5

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

    • @Kingbimmy
      @Kingbimmy 4 місяці тому +1

      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
      @incognitoburrito6020 4 місяці тому +5

      ​@@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
      @greegorygrimlee5487 Місяць тому

      ​@@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.

  • @tirterra1222
    @tirterra1222 5 місяців тому +359

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

    • @the_akshay_p
      @the_akshay_p 5 місяців тому +20

      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
      @_John_P 5 місяців тому +5

      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 5 місяців тому

      😂🥲

    • @goldnutter412
      @goldnutter412 5 місяців тому

      33 minutes ago@@_John_P

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      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
      @waelfadlallah8939 5 місяців тому +1

      I am waiting for barber pole effect part 3 pleasssssssssse!

  • @paparapiropip87
    @paparapiropip87 5 місяців тому +465

    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
      @runakovacs4759 5 місяців тому +5

      Spectroscopy for life!

    • @onradioactivewaves
      @onradioactivewaves 5 місяців тому +8

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

    • @davidrandell2224
      @davidrandell2224 5 місяців тому +3

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

    • @atticuswalker
      @atticuswalker 5 місяців тому +1

      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
      @newuser689 5 місяців тому +3

      ​@@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.

  • @tHaTsWhAtI.mSaYiNg
    @tHaTsWhAtI.mSaYiNg 5 місяців тому +38

    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'

  • @abrahanpinedo
    @abrahanpinedo 5 місяців тому +48

    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.

  • @HuygensOptics
    @HuygensOptics 5 місяців тому +58

    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
      @Arnogorter 5 місяців тому +6

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

  • @Pidrittel
    @Pidrittel 5 місяців тому +45

    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
      @godoit7569 5 місяців тому +1

      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
      @Beny123 5 місяців тому +1

      Your nitpicky maths brain 😢 . Indeed it is

    • @stylis666
      @stylis666 5 місяців тому

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

  • @jakeadams2562
    @jakeadams2562 5 місяців тому +24

    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.

  • @NiMareQ
    @NiMareQ 4 місяці тому +9

    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!

  • @xminty77
    @xminty77 5 місяців тому +56

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

  • @alessandrolodi8951
    @alessandrolodi8951 5 місяців тому +79

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

    • @pitCest
      @pitCest 5 місяців тому +1

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

    • @VeganSemihCyprus33
      @VeganSemihCyprus33 5 місяців тому

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

    • @berryesseen
      @berryesseen 5 місяців тому +7

      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 UA-cam.

    • @piman7319
      @piman7319 5 місяців тому

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

  • @AlphaPhoenixChannel
    @AlphaPhoenixChannel 5 місяців тому +17

    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 😁

  • @DellHell1
    @DellHell1 5 місяців тому +12

    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.

  • @Anjihyu
    @Anjihyu 5 місяців тому +46

    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.

  • @nathanaelhahn4795
    @nathanaelhahn4795 5 місяців тому +16

    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!

  • @sirmr6597
    @sirmr6597 4 місяці тому

    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.

  • @cegalleta
    @cegalleta 5 місяців тому +5

    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

  • @AdityaPatwardhanJ
    @AdityaPatwardhanJ 5 місяців тому +16

    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 :)

  • @gustavinho1510
    @gustavinho1510 5 місяців тому +5

    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.

  • @helved807
    @helved807 5 місяців тому

    This was actually spectacularly done! It really showed intuitively why all those mechanics work and how they add up to create the system we see. Massive props for you demonstrating the lecture content in a cool way!

  • @RishabhSharma10225
    @RishabhSharma10225 5 місяців тому +3

    Braingasm. Every time I watch a 3B1B video.

  • @adjsmith
    @adjsmith 5 місяців тому +20

    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.

  • @srroome
    @srroome 5 місяців тому +15

    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.

  • @NowhereNear42
    @NowhereNear42 10 днів тому

    I have no words for how brillantly this is explained! This is very, very high quality teaching.

  • @user-be8uq2th4f
    @user-be8uq2th4f 5 місяців тому

    This is so amazing! I've struggled so much with textbooks and ivy league profs trying to describe this - it always ended up just being arcane gibberish. The brilliantly intuitive explanations combined with the simulations do so much to demystify a frequently opaque subject, even to people like myself who used to work a lot with optics!

  • @GroovingPict
    @GroovingPict 5 місяців тому +57

    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.

  • @leokyle6195
    @leokyle6195 5 місяців тому +11

    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

  • @SilverwingVFX
    @SilverwingVFX 5 місяців тому

    Wow. Again I Have to express how well made your videos are. Its amazing how much finesse those animations have!
    I am super glad this exists. I will definitely use it in my shading classes for 3D Artists. Its always good to dive deeper and your videos are the gold standard for this!

  • @patrickmuller3248
    @patrickmuller3248 3 місяці тому

    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.

  • @luckyw4ss4bi
    @luckyw4ss4bi 5 місяців тому +5

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

  • @JoelFishel
    @JoelFishel 5 місяців тому +11

    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
    @EletronicaCaseira 5 місяців тому +3

    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!

  • @AlbertMartino17
    @AlbertMartino17 4 місяці тому +2

    This is incredible. I've never thought to explore derivations of Snell's. These explanations really show the value of animation in education of new concepts, since the hardest part of "understanding" something usually has to do with making some subpar version of these visualizations in your own head... Thanks for all your hard work!

  • @borisjoukov
    @borisjoukov 5 місяців тому +51

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

    • @waelfadlallah8939
      @waelfadlallah8939 5 місяців тому

      I am waiting for barber pole effect part 3 pleasssssssssse!

    • @MadScientist267
      @MadScientist267 5 місяців тому

      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
      @VeganSemihCyprus33 5 місяців тому

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

  • @berryesseen
    @berryesseen 5 місяців тому +4

    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.

  • @manuel_ao
    @manuel_ao 5 місяців тому

    Thank you Grant for such a thoughtful and well-animated video and thanks to Richard Feynman for all the intuitive answers that he has provided to so many physicists. I will re-watch videos 1 - 3 again but I would love a video that wraps up everything to explain the barber pole animation.

  • @suddhasattasaha4793
    @suddhasattasaha4793 4 місяці тому +2

    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.

  • @hurshasnarayan
    @hurshasnarayan 5 місяців тому +7

    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. 🙏🏽

  • @user-rm2qj2jh4l
    @user-rm2qj2jh4l 5 місяців тому +40

    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
      @waelfadlallah8939 5 місяців тому

      I am waiting for barber pole effect part 3 pleasssssssssse!

    • @atticuswalker
      @atticuswalker 5 місяців тому

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

    • @MadScientist267
      @MadScientist267 5 місяців тому

      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
      @VeganSemihCyprus33 5 місяців тому

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

  • @DiaryOfAGhost_StreetsOfTempe
    @DiaryOfAGhost_StreetsOfTempe 4 місяці тому +1

    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 😊

  • @erinm9445
    @erinm9445 5 місяців тому +2

    Thank you so so much for this incredible series! I have been trying (and failing!) to understand how light could slow down in a material, none of the other explanations made any sense. But your incredible visualizations and clear explanations have finally helped me to understand!

  • @estrheagen4160
    @estrheagen4160 5 місяців тому +5

    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.

  • @lazarussevy2777
    @lazarussevy2777 5 місяців тому +4

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

  • @mcv2178
    @mcv2178 5 місяців тому

    THANK YOU! About a year ago I got curious and tried SO hard to find this out! I was not even sure how to ask what I wanted, and got nowhere, and gave up, and now you have given me what wanted to know, without even being asked : )

  • @fdert
    @fdert 5 місяців тому +1

    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.

  • @santig0_
    @santig0_ 5 місяців тому +4

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

  • @cookieslammer6411
    @cookieslammer6411 5 місяців тому +8

    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.

  • @shikhanshu
    @shikhanshu 5 місяців тому

    The level of detail is staggering in these videos... one of the most important youtubers out there

  • @DerProfessor626
    @DerProfessor626 3 місяці тому +1

    Bro after my physics studies for becoming a teacher I knew eversthing except for why the light slows down. It was so incredibly well explained and animaded, I will probably use your video to explain this to my students as well! ❤

  • @kolavithonduraski5031
    @kolavithonduraski5031 5 місяців тому +3

    25:07 as a civil/structural engineer i appreciate your didactic approach to simplify light movement with springs, the millenium bridge and the swing (mechanical motion).
    I understood almost everything👍😁

  • @9darkspells
    @9darkspells 5 місяців тому +12

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

  • @svmchop
    @svmchop Місяць тому

    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..

  • @davidhjortshoej4774
    @davidhjortshoej4774 5 місяців тому

    The animations are always so satisfying. Goes right to the heart of a visual thinker

  • @FoughtAgaisntSisera
    @FoughtAgaisntSisera 5 місяців тому +6

    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

  • @landonkryger
    @landonkryger 5 місяців тому +3

    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.

  • @RobinWootton
    @RobinWootton 4 місяці тому

    Amazing how you churn these out. This would be more than a lifetime's work for some of us!

  • @roshini723
    @roshini723 5 місяців тому +3

    I'm a physicist and your videos are helpful when I try to understand mathematical concepts visually. Could you also make a video on Surface Plasmon Effect? I would say it fits perfectly to your series you're currently making on optics.

  • @davidyounghans7243
    @davidyounghans7243 5 місяців тому +3

    Great explanation, as always. My favorite physics book, Thinking Physics by Lewis Epstein, uses the metaphor of a man running into the ocean at an angle to explain why (and how) light refracts when it enters a slower medium. A picture would be a lot better here, but, to take the least time to get from point A (on land) to point B (in water), the man runs along the beach longer than if the entire path were straight, then turns at close to the last second before entering the water. If light takes the least-time path from point A to point B, it follows a similar path.

  • @PulseCodeMusic
    @PulseCodeMusic 5 місяців тому

    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.

  • @YanivGorali
    @YanivGorali 5 місяців тому

    This channel is a treasure that keeps on giving

  • @WarzoneMasters
    @WarzoneMasters 5 місяців тому +6

    i learned so so much with your videos respect forever ♾️

    • @waelfadlallah8939
      @waelfadlallah8939 5 місяців тому

      I am waiting for barber pole effect part 3 pleasssssssssse!

  • @Youtubehastoomanyads
    @Youtubehastoomanyads 5 місяців тому +20

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

    • @waelfadlallah8939
      @waelfadlallah8939 5 місяців тому

      I am waiting for barber pole effect part 3 pleasssssssssse!

    • @gw6667
      @gw6667 5 місяців тому

      *math

    • @iqwit
      @iqwit 5 місяців тому

      ​@@gw6667not everyone is American my guy

  • @JordanMcCaughey
    @JordanMcCaughey 5 місяців тому

    Just in time for my advanced electromagnetism exam. This is a great video, exactly the visualisations the topic needs! I hadn't grasped how the phase "kick-back" was at every point in the material but your visualisation has totally cleared it up!

  • @thuytienlives8487
    @thuytienlives8487 5 місяців тому

    This is a really great video with fantastic pictures and explanations. Thank you, Grant.

  • @Codexionyx101
    @Codexionyx101 5 місяців тому +6

    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.

  • @890sigma
    @890sigma 5 місяців тому +20

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

    • @gw6667
      @gw6667 5 місяців тому

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

    • @890sigma
      @890sigma 5 місяців тому

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

    • @GaussianEntity
      @GaussianEntity 5 місяців тому

      ​​@@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.

  • @jonahansen
    @jonahansen 5 місяців тому +1

    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.

  • @Elfstones3n1
    @Elfstones3n1 4 місяці тому +1

    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!)

  • @weksauce
    @weksauce 5 місяців тому +3

    Murmurs to self: This isn't how mom does it.

  • @capitaopacoca8454
    @capitaopacoca8454 5 місяців тому +3

    Since temperature is the wiggling of particles, doesn't temperature affect this? Or it's a random wriggle so its effects cancel out?

    • @MaxIV77
      @MaxIV77 5 місяців тому

      Not an informed response. But I would think it can largely be separated from the math he is doing in the video. Unless you are getting to temperatures where the integrity of the bonds of the material are being messed with (think melting or changing density) I would think you could treat the electric fields as a superposition of whatever equations you come up with.

  • @user-mm9xr8zd7m
    @user-mm9xr8zd7m 5 місяців тому

    One of the greatest videos ive seen in a while.
    Huge thanks from France

  • @ophthojooeileyecirclehisha4917
    @ophthojooeileyecirclehisha4917 27 днів тому

    thank you so much for your science, kindness, information, hard work, design, and generosity

  • @VJfication
    @VJfication 5 місяців тому +6

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

  • @jaroel
    @jaroel 5 місяців тому +5

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

  • @MTEXX
    @MTEXX 21 день тому

    What an amazing deep-dive and clear explanation with immaculate animations. All in 30 minutes???? Wow.

  • @dcterr1
    @dcterr1 5 місяців тому

    Excellent explanation! This is even better than the first draft, since this one goes into more detail and was easier for me to follow.

  • @lucasthompson1650
    @lucasthompson1650 5 місяців тому +11

    I clicked on this video thinking it was a Pink Floyd thing...

    • @michaelstanley1326
      @michaelstanley1326 11 днів тому +1

      then you ended just as happy

    • @lucasthompson1650
      @lucasthompson1650 11 днів тому

      @@michaelstanley1326 Probably a little happier, actually, I think. Or at least, I don’t know anyone who’s ever locked themselves in their room and spent 24 hours engaged in optics puzzles after a harsh breakup.

  • @gabrielhamrle2779
    @gabrielhamrle2779 5 місяців тому +3

    3Blue1Brown started creating physics viedoes so that we would study something useful and not pure mathematics.

  • @Koutentogiwrghs
    @Koutentogiwrghs 5 місяців тому

    Amazing presentation. You explained concepts that have so much jargon associated to them so clearly. Phasors, Lorentz oscillator models, scattering phase shifts etc. I have not seen such a good physics presentation, even from physics channels.

  • @lousi47
    @lousi47 5 місяців тому

    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

  • @beemerwt4185
    @beemerwt4185 5 місяців тому +1

    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).

  • @atil4
    @atil4 5 місяців тому +1

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

  • @deneshk353
    @deneshk353 5 місяців тому

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

  • @thecomputerscientist209
    @thecomputerscientist209 18 днів тому

    Amazingly explained. All hands down. This explanation works with one photon at a time as well, as the wave function interacts with everything producing the same result.

  • @jayakrushnasahoo4403
    @jayakrushnasahoo4403 5 місяців тому

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

  • @mp3lwgm
    @mp3lwgm 7 днів тому

    This is a bold and effective representation of Feynman’s ideas concerning the origin of refractive index. I think it is important to note that the charges actually driven to wiggle by the plane wave would be the electrons within the atoms in the sheet. They are negatively charged, not positive.

  • @usptact
    @usptact 5 місяців тому

    Just beautifully explained! I must confess that I never knew how a prism works, even after all those physics lessons and courses!

  • @LesLaboratory
    @LesLaboratory 5 місяців тому

    This is beautiful work! Love the intuitive explanation, as well as the animations. I would love to see a video like this on Second Harmonic Generation.

  • @Sollys3
    @Sollys3 5 місяців тому

    I like a lot of your videos, but I think there are very few that genuinely taught me as much as this one

  • @Divineskulls1
    @Divineskulls1 5 місяців тому

    This is a perfect video that explains not only the dissemination of knowledge ("on high" vs. explained) and the nature of light at the quantum layer

  • @dete9191
    @dete9191 5 місяців тому

    I really love these kind of physics explanatory videos, keep it up!

  • @MeepMu
    @MeepMu 5 місяців тому +2

    I've been studying vibration for this past week and messing around with these equations, so a lot of this is very recognizable at the moment. What a nice coincidence that this video comes out now, as it's answering a few questions I've been having 😅

  • @luisfranciscocordero9627
    @luisfranciscocordero9627 4 місяці тому

    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!