Imaginary Numbers Are Real [Part 1: Introduction]

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  • Опубликовано: 5 янв 2025

Комментарии • 4,1 тыс.

  • @masterstealth11
    @masterstealth11 7 лет назад +4665

    “We’ll be using the term lateral from now on”
    *continues to say imaginary*

  • @SuperPBrady
    @SuperPBrady 5 лет назад +537

    I’m a tutor and every time I explain imaginary numbers to precalculus students they are so confused. Your graphic here illustrates it perfectly. Thank you for taking the time to do this!

    • @-Burb
      @-Burb 5 лет назад +15

      Paige Brady
      Precalc students don’t understand imaginary numbers by that point?

    • @xwqkislayer7117
      @xwqkislayer7117 4 года назад +28

      Ngl this graph is.harder to understand than explaining it normally.

    • @UTU49
      @UTU49 3 года назад +17

      @@-Burb
      Tons of people take a Calculus course who have very weak algebra. It makes it damn hard for them to pass it, but that's just the way it is.
      I sometimes wonder if they shouldn't let someone take a Calculus course at all unless they got a B+ in an algebra course... RECENTLY.
      Letting them take it on the strength of getting a C+ in an Algebra course 4 years ago: that's just setting them up for failure.
      My brother, my research supervisor, and myself: all 3 of us failed a Calculus course after getting As in high school math. Obviously we just weren't doing any work, but it illustrates that even if you did well in high school math, you can still fail Calculus. Everyone should therefore not even start a Calculus course unless their Algebra is solid.

    • @UTU49
      @UTU49 3 года назад +1

      I've also tutored math. I don't recall helping students with Complex math a lot, but I would just tell them that imaginary numbers are, in a sense, less real than "Real" numbers... but that they are still useful.

    • @andreeacat7071
      @andreeacat7071 3 года назад

      @@UTU49 It’s because most of the people taking precalculus are either seniors or juniors, since some schools don’t offer the first level of math in 7th grade option that allows sophomores to take it. Seniors don’t really care about the material and may not even understand it because if they didn’t care to learn it earlier than senior, chances are they’re just doing it for credit.

  • @billcannon
    @billcannon 9 лет назад +3973

    You delighted me with the 3D lateral-plane visualization. Well done.

  • @aTomallic
    @aTomallic 2 года назад +1112

    I remember a time where I was joking around with my algebra 1B teacher;
    "Hey it's kind of wacky that the calculator responds no real numbers does that imply the existence of imaginary numbers?"
    "Yes."
    I cannot describe the internal panic I had at the idea of seemingly non-existent numbers.

    • @hareecionelson5875
      @hareecionelson5875 2 года назад +62

      Yo, that's a kick in the discovery, I wish I had thought of that before when I was taught about the set of all real numbers

    • @whatname3676
      @whatname3676 2 года назад +4

      Wait, calculators don't respond real numbers?

    • @deleted-something
      @deleted-something 2 года назад +1

      Rip

    • @the_demon149
      @the_demon149 2 года назад +48

      Something similar happened to me lol. And then the teacher just breezed right by it! It was mid lesson, and she was just like “Oh yeah numbers that don’t exist exist, but that’s high school stuff, anyway…”

    • @john-ic5pz
      @john-ic5pz Год назад +14

      ​@@the_demon149so sad they didn't digress for a minute. minds are open far before H.S....perhaps more so

  • @kswiorek
    @kswiorek 6 лет назад +1790

    In polish it's even worse. Imaginary numbers are "liczby urojone", "uroić" means to hallucinate...

    • @pan_czerwony5437
      @pan_czerwony5437 6 лет назад +9

      czyli dokładnie to samo

    • @kswiorek
      @kswiorek 6 лет назад +28

      @@pan_czerwony5437 imaginary to bardziej wymyślone, imagination to wyobraźnia i to nie ma takiego negatywnego znaczenia.

    • @pan_czerwony5437
      @pan_czerwony5437 6 лет назад +10

      @@kswiorek Ale to synonimy,a w Angielskim jest dość mały zasób słów w porównaniu z Polskim wiec można uznać to za to samo,ale rozumiem tok myślenia

    • @swinki33
      @swinki33 6 лет назад +54

      @@pan_czerwony5437
      What did π say to i (the square of -1) ? Get real (ie. not imaginary)!
      What did i say back? Be rational
      Evergreen math joke :)

    • @pan_czerwony5437
      @pan_czerwony5437 6 лет назад +5

      @@swinki33 oh god

  • @Black_Kakari
    @Black_Kakari 5 лет назад +4017

    Brah, he pulled a rainbow out of his paper.
    Drugs

  • @jalfire
    @jalfire 6 лет назад +13040

    thank you Gauss. It sounds much less awkward to say that I have a lateral girlfriend

    • @QED_
      @QED_ 6 лет назад +109

      @Jalfire: Me . . . I just keep it to myself and don't mention it to anyone else at all.

    • @ShizL
      @ShizL 6 лет назад +46

      so original

    • @alvarogoenaga3965
      @alvarogoenaga3965 6 лет назад +170

      @@QED_ lateral girlfriend= mistress

    • @sauceaddict9569
      @sauceaddict9569 5 лет назад +13

      Lmfao😂😂

    • @miguelalvesmacedo
      @miguelalvesmacedo 5 лет назад +19

      still awkward though

  • @eziola
    @eziola 2 года назад +49

    Man, this is one of the greatest, mind-opening playlists about the beauty of math that has ever been posted to RUclips. This taught me to see algebra visually. Absolutely incredible. You are so talented. Why did you stop making series like these? They're incredible!

  • @patrickjmt
    @patrickjmt 8 лет назад +1775

    This series of videos is really amazing, great job and keep it up!

    • @ofentsetshepe
      @ofentsetshepe 8 лет назад +29

      hey patrick ..best maths teacher/professor/tutor on youtube

    • @obsidiansiriusblackheart
      @obsidiansiriusblackheart 7 лет назад +11

      Ayyy Patrick shoutout for being the reason I passed first year maths 👌 👌 👌

    • @JunieHaloway
      @JunieHaloway 7 лет назад +3

    • @krisfix7982
      @krisfix7982 7 лет назад +6

      Shoutout to forpatricks for also the reason why i passed all my classes lol

    • @Madmun357
      @Madmun357 6 лет назад

      Patrick, your videos are my Go-To videos.

  • @blazeknight2009
    @blazeknight2009 8 лет назад +140

    The presentation of math has never been so fun and interesting like this one here. Kudos to thee. 10/10

    • @WelchLabsVideo
      @WelchLabsVideo  8 лет назад +7

      Thank you!

    • @harmitchhabra989
      @harmitchhabra989 6 лет назад +2

      @@WelchLabsVideo Keep Making *Great* Videos. And Thank You For Such An *Amazing* Explanation.😀

  • @rinfeast3445
    @rinfeast3445 5 лет назад +2437

    its all fun and games in math class until the graph starts speaking 3d

    • @Email5507
      @Email5507 4 года назад +54

      You will see Fourth Dimension in future, which you will not express or understand in 2d papers like you do 3 dimensional shapes.

    • @lindaday884
      @lindaday884 4 года назад +2

      be still my heart!

    • @vladymartinez1232
      @vladymartinez1232 4 года назад +20

      @@Email5507 impossible to understand, impossible to imagine, we can only "speak" about it, i love it!!!!

    • @khodis2002
      @khodis2002 3 года назад +3

      Imagine classes in vr headsets

    • @lukiepoole9254
      @lukiepoole9254 3 года назад +3

      fourth dimension is rotate in 3d space. It would have a pitch, roll, and yaw. It's quaternion.
      Fun fact about bi-nion and quaternion. They are MATRIX.

  • @br1lliantplanets643
    @br1lliantplanets643 4 года назад +1176

    By the way, imaginary numbers ARE called “lateral numbers” in China.
    It could just because it’s easier to pronounce(less syllables in the Chinese language), but Gauss would be proud

    • @morgiewthelord8648
      @morgiewthelord8648 4 года назад +18

      Very cool

    • @nvitined
      @nvitined 4 года назад +34

      Well, imaginary numbers in Chinese still has the ‘imaginary’ meaning. It’s called 虛數 I think

    • @masterspark9880
      @masterspark9880 3 года назад +203

      “The Tiananmen Square protests are lateral”

    • @user-vv1do1wg1j
      @user-vv1do1wg1j 3 года назад +6

      @@masterspark9880 LMAO

    • @jasonmaguire7552
      @jasonmaguire7552 3 года назад +3

      @@masterspark9880 legendary

  • @august_klevberg
    @august_klevberg 5 лет назад +2346

    The easiest way to understand negative numbers is by picturing my bank account.. 😔

    • @zekzimbappe5311
      @zekzimbappe5311 5 лет назад +24

      And if u don't have any account like me

    • @spartanhead8131
      @spartanhead8131 5 лет назад +11

      @@zekzimbappe5311 Watch other peoples poor bank accounts.

    • @bufdud4
      @bufdud4 5 лет назад +30

      @@zekzimbappe5311 then that's lateral bank account

    • @umniyahirfan5026
      @umniyahirfan5026 5 лет назад +1

      I LOVE YOUUU

    • @Nick-ui9dr
      @Nick-ui9dr 5 лет назад +4

      And mine imaginary numbers. ;)

  • @Kugelschrei
    @Kugelschrei 8 лет назад +877

    I never knew I could have that much fun watching a math video, well done.

    • @StormCougarTypeZero
      @StormCougarTypeZero 8 лет назад +11

      Standupmaths mang

    • @TomCatFromMA
      @TomCatFromMA 8 лет назад +3

      More real world applications would've been nice for us noobs. So, thumbs down.

    • @theviniso
      @theviniso 8 лет назад +6

      Numberphile has some cool video too

    • @DoomRater
      @DoomRater 7 лет назад +4

      KommentarKanal I knew I was in for a show the minute the video title mentioned imaginary numbers being real. Better Explained already demonstrated how the number line is really a number plane, and how multiplying by /i/ is like rotating rather then scaling or stretching, but seeing it visualized like that made my day.

    • @iOSMinecraft120
      @iOSMinecraft120 7 лет назад +3

      Mathologer is cool too :)

  • @TJShare
    @TJShare 4 года назад +130

    Thank you so much! Your 3d animation was apparently what I needed for the imaginary numbers to finally make sense. It's a great feeling discovering the missing piece you need to understand a concept.

  • @maxwellscheinfield6612
    @maxwellscheinfield6612 3 года назад +43

    I show this first video of the series every single semester that I teach Algebra students about "imaginary" numbers for the first time. Really gets through to them!

    • @JoseVega-td3iw
      @JoseVega-td3iw 8 месяцев назад

      I just did the same an hour ago.

  • @mab3667
    @mab3667 7 лет назад +403

    2:50 I know many of you just wanted to see this

    • @rlyrosy
      @rlyrosy 5 лет назад +2

      💖💖

    • @juvenileygo
      @juvenileygo 5 лет назад +19

      But a nerd like me wants explanation on how he solved the equation. Sadly he got nothing

    • @definesigint2823
      @definesigint2823 5 лет назад +3

      @@juvenileygo Note, this is first in a series of 13 videos (all published here).

    • @juvenileygo
      @juvenileygo 5 лет назад +2

      @@definesigint2823 tldw, he simply added a new dimension. Basically saying lets add imaginary axis to solve imaginary number. Hence no wonder he didnt get anything but views and clicks

    • @definesigint2823
      @definesigint2823 5 лет назад +1

      @@juvenileygo (nods, thanks for clarifying) When I first saw these I was looking for a quick answer to the equation. While I didn't regret watching the series, it was a decision I hadn't expected to make when I first clicked.

  • @DrPG199
    @DrPG199 4 года назад +1280

    The easiest way to understand real and imaginary numbers is by using my bank account balance as an example: its real part is $10 and its imaginary part is $10 million dollars.

  • @Eric-jb1ym
    @Eric-jb1ym 8 лет назад +614

    Production is top notch

    • @g00dvibes47
      @g00dvibes47 8 лет назад +78

      so is the explanation. concise, accurate, visually easy to understand. trifecta

  • @kentGrey
    @kentGrey 3 года назад +2

    SWEET! You managed to tell us and show us what you're telling us within the first 2 minutes and used the remaining time to expand upon it. instant subscription!

  • @samovarmaker9673
    @samovarmaker9673 7 лет назад +2026

    Math: If I have two apples, and I give you one, I will have one apple left.
    Finance: If I have two apples, and I give you one, you will have to repay me the apple in full after a set period of time, plus interest which is to be calculated as a percentage rate of the apple divided by the amount of time it took you to repay me the apple in full.

    • @abdulhermiz782
      @abdulhermiz782 7 лет назад +60

      Very true indeed.

    • @jimmybelgium
      @jimmybelgium 7 лет назад +19

      How do I always see see you? On every geography now video I've seen ur comment and now on math? Holy crap man

    • @pebblepod30
      @pebblepod30 7 лет назад +125

      Politics: If I have one apple, and I give you one, everyone will shout & scream that they didnt get one & band together to try to force me to give them apples.

    • @pebblepod30
      @pebblepod30 7 лет назад +34

      Economics: I have two apples, I give you one, but few people realize that apples are produced in a farm, and are worried that there isn't enough, and not even Apple farmers seem to know where apples come from (except the Bank of England Apples which plainly stated the truth).
      I'm MMT. A Neoclassical Economist would describe things that I think are not true and responsible for the mess economies are in (because they are run on the assumption that the currency issuer should behave like a currency User, & other things that don't apply anymore to modern money):
      ruclips.net/video/TDL4c8fMODk/видео.html

    • @igamingmp1526
      @igamingmp1526 7 лет назад +8

      Finance is math

  • @priyavartrajain2166
    @priyavartrajain2166 5 лет назад +24

    Watched the whole series, honestly, for the first time in my life, i actually understood what was going on in my math class! Great Job dude!

  • @TheEclipsedLock
    @TheEclipsedLock 7 лет назад +301

    What pulled me in was the 3D graph in the thumbnail :p

    • @josepablobermudez6283
      @josepablobermudez6283 5 лет назад

      same

    • @tgw607
      @tgw607 4 года назад

      @@josepablobermudez6283 Me too. I wonder if you can make that with a 3d printer or do you need a 4d?

  • @nehalkalita1
    @nehalkalita1 2 года назад +3

    Your efforts for making a whole playlist on imaginary numbers is worth of appreciation. Very few can explain in details.

  • @Norman_Lazarevich
    @Norman_Lazarevich 5 лет назад +434

    If you ever feel dumb,just remember at somepoint you can do what Leonhard Euler can't.

    • @whycity2057
      @whycity2057 4 года назад +90

      Feeling dumb must not be considered as a problem, it's the first step to get a solution, if you are aware that you are dumb ,then only you can become more wise by sorting out and solving the reasons, because only you know what's inside your head, so only you have the ability to make yourself bright.
      Rather than ignoring dumbness,cure it.

    • @HighestRank
      @HighestRank 4 года назад +5

      couldn’t *

    • @afreen5058
      @afreen5058 4 года назад +4

      *slowly applaudes *
      I love this comment. Its perfect.

    • @machomachinmachinmachinmac6910
      @machomachinmachinmachinmac6910 4 года назад +1

      Was he from Houston?.......The Houston Eulers.

    • @hubb8049
      @hubb8049 3 года назад +1

      @@machomachinmachinmachinmac6910 He was from Basel

  • @wawathulu5637
    @wawathulu5637 5 лет назад +696

    Therapist: The square root of -1 can't hurt you, it doesn't exhist.
    The square root of -1:

    • @akuljamwal3085
      @akuljamwal3085 5 лет назад +55

      _[Imaginary Screams]_

    • @Tatiana-jt9hd
      @Tatiana-jt9hd 4 года назад +63

      *_[Lateral Screams]_*

    • @AnhThuNguyen-zz2hm
      @AnhThuNguyen-zz2hm 4 года назад +6

      *exist

    • @mtlicq
      @mtlicq 4 года назад +3

      square root of 1 can't hurt, but square root of -1 hurts!

    • @jimr8552
      @jimr8552 4 года назад +1

      Neither can division by 0 - oh wait is this the year 2020? You haven't gotten to n based multidimensional mathematics yet.

  • @filipmarkovic2121
    @filipmarkovic2121 6 лет назад +8

    This is by far the best-presented video on mathematics I saw in my life. 10/10 for your pedagogical skills.

  • @newtonlkh
    @newtonlkh Год назад +5

    I just happened to think of this amazing series again, and searched to see how the channel is doing now, and discovered that it got active again 2 weeks ago! Lucky me. Lucky us. The world would benefit much from your inspiration! Hope this comment would give you a little boost of encouragement for your upcoming work!

  • @moistnapkin1599
    @moistnapkin1599 5 лет назад +431

    Title:
    Mathematicians: Well yes but actually no

    • @Goosnav
      @Goosnav 5 лет назад +8

      Reddit moment!

    • @cmswrD
      @cmswrD 5 лет назад +1

      @@Goosnav Goosnav

    • @139-b7j
      @139-b7j 4 года назад +10

      @@Goosnav destruction 100
      holy shit you destroyed him dude
      you're breathtaking
      wholesome big chungus

    • @CarbonRollerCaco
      @CarbonRollerCaco 4 года назад

      Naw, negative numbers are the real Schrödinger's numbers.

    • @AlineSanchezRamirezBaruc-xm6qb
      @AlineSanchezRamirezBaruc-xm6qb 3 года назад

      Every number is a representation, just like signs

  • @jonkrieger5271
    @jonkrieger5271 8 лет назад +313

    Awesome video! I loved that visualization where you pulled the surface out of the flat paper, that was a big WOW moment! I've worked with imaginary numbers a ton, I studied physics in college, but this video still had an affect on deepening my understanding. Excited to watch the rest!

    • @theviniso
      @theviniso 8 лет назад +13

      A picture is worth a thousand words

    • @frother
      @frother 8 лет назад +14

      What I don't understand about that visualization is that after he pulls the surface out, there are an *infinite* number of roots. I thought he just said that there are exactly as many roots as the degree of the polynomial?

    • @EthanGarcia-n1ov7zi
      @EthanGarcia-n1ov7zi 8 лет назад +6

      frother - There actually only two roots. The "infinite" intersection of the 3d parabola to the imaginary plane is actually just the extension of the whole parabola through 3 dimensions (x, y, i ). Two roots can be seen by taking a different "slice" view point along the new dimension parallel to the coordinate plane (3 units above paper). This will give a new coordinate view of the parabola that does indeed intersect at two points.

    • @qorilla
      @qorilla 8 лет назад +12

      That's a good point, but it's only a problem with the visualization. In fact there are only two roots.
      The problem is that to really plot the function, we would need 4 dimensions, not just 3, since the input of the function requires 2 dimensions (real and imaginary/lateral) and the output is also a complex number so it would also need 2 dimensions to plot properly. In this visualization they simply didn't plot the imaginary part of the output value of the function, only the real part. And there are indeed infinitely many complex numbers whose square's real part is -1. But for most of them there is a nonzero imaginary part (except for the 2 actual roots, i and -i).

    • @frother
      @frother 8 лет назад +4

      Thanks, I never expected to get such a clear and helpful answer from the youtube comments!

  • @dominikscherer1882
    @dominikscherer1882 5 лет назад +47

    This is one of the best explanations I heard about anything. Incredibly well done and "easy" to understand! I wish they could teach at university or school like this :/

  • @j.a.l.m.9464
    @j.a.l.m.9464 2 года назад +6

    Great video. If algebraic concepts were explained this way in all schools, there would be far more students interested in Maths and Science. Keep the good work!

  • @jeremybuckets
    @jeremybuckets 7 лет назад +63

    "From here on, let's let lateral mean imaginary."
    Continues to use "imaginary" through the rest of the video.

  • @naviddavanikabir
    @naviddavanikabir 8 лет назад +64

    for those who just started watching this, make absolutely sure you watch all the way to part 13.
    prepare to be blooooowwnnn.
    awesome series.

  • @nuklearboysymbiote
    @nuklearboysymbiote 4 года назад +134

    euler: -1 > ∞
    He predicted integer overflow

    • @xwqkislayer7117
      @xwqkislayer7117 4 года назад +4

      Can you specify what integer overflow is? I'm sorry I dont know lol.

    • @nuklearboysymbiote
      @nuklearboysymbiote 4 года назад +36

      @@xwqkislayer7117 in computer systems, if a number is too big to be stored, it loops back to a negative number
      example: Let's say we have a binary system that can store 8 numbers: 000, 001, 010, 011, 100, 101, 110, 111
      If we want to represent negative numbers, it makes sense to put them before the positive ones, so let's say:
      000 = -4
      001 = -3
      010 = -2
      011 = -1
      100 = 0
      101 = 1
      110 = 2
      111 = 3
      so the biggest number we can represent is 3. If we had another digit, we could have:
      1000 = 4
      But we don't. So if we tried to ”add 1” to our 3, it would be:
      111 + 1 = (1)000
      so our system would see 000 and think it is -4
      This is integer overflow, when we don't have enough digits to represent big numbers which causes a mistake that turns it negative.

    • @xwqkislayer7117
      @xwqkislayer7117 4 года назад +5

      @@nuklearboysymbiote Thanks I didnt know that lol

    • @nuklearboysymbiote
      @nuklearboysymbiote 4 года назад +23

      @@xwqkislayer7117 i simplified it a little bit to get the idea across, please keep in mind this is not exactly how computers represent numbers. computers are actually built to represent negative numbers using a thing called two's complement: if you have a positive number, flip all the digits, then add 1, that will be how you represent its negative.
      This way, we can actually represent 0 as 000
      e.g.: 2 is represented as 010
      so to get -2, you do 101 + 001 = 110
      this way, you can add the individual digits to get 0 back:
      2 + (-2) = 0
      010 + 110 = (1)000
      The maths is easier this way. That also makes it easier to recognise which numbers are negative, as the first digit will be 1 if it's negative, and 0 if it's positive (-2 = 110, +2 = 010)

    • @xwqkislayer7117
      @xwqkislayer7117 4 года назад +5

      @@nuklearboysymbiote ah ok ill keep that in mind. Thanks for the info

  • @JabrHawr
    @JabrHawr 3 года назад +5

    i'm loving this. gotta bookmark this and watch the rest of the parts.
    the talk about the negatives being 'unnatural and weird' is extremely relatable - not now of course, but back when i was in school when i was first introduced to it.
    and then you use this very relatable notion to explain how 'imaginary' numbers are exactly the same in that they may _feel_ unnatural but in truth they aren't (just like how we initially felt about negatives) - that is so good and appreciated. very exciting.

  • @quantumsmith371
    @quantumsmith371 9 лет назад +6

    never stop doing these videos they are the best out there. thank you so much for taking the time to share them. with us.

  • @poposterous236
    @poposterous236 5 лет назад +110

    I remember when Mrs. Cerigo introduced imaginary numbers, I just threw up my hands and said, "Well, that does it, they've run out of stuff to teach us. Now they're just making things up."
    Glad to know I was wrong.

    • @sonalidasgupta3562
      @sonalidasgupta3562 5 лет назад +2

      ...but...you were RIGHT....they did "make-it-up".....😈
      ....God made the Natural numbers; everthing else is "made-up" 😆 ..(misquoting Kronecker)

    • @simonO712
      @simonO712 5 лет назад +7

      I mean, _all_ of mathematics is "made up". That doesn't make it any less useful though.

    • @-Burb
      @-Burb 5 лет назад +11

      simonO712
      No, all of math is discovered.
      The symbols we make are made up, but math itself if completely real and all discovered.

    • @arya6085
      @arya6085 4 года назад +1

      @BeetleBUMxX you're just calling everything in this comment section cute.
      Pretty cute ngl :)

    • @АлёшаИнкогнитов
      @АлёшаИнкогнитов 4 года назад +2

      @@-Burb LOL. This makes no sence.
      It's like to say "we invented letters, but languages are all discovered". Even worst, cause words are always related to something real, but math just don't give a F about reality.

  • @thevirtuousghost9480
    @thevirtuousghost9480 7 лет назад +249

    The anti-apple

  • @itsiz9738
    @itsiz9738 3 месяца назад

    Suddenly remembered watching this whole series as a kid. I barely even knew what imaginary numbers but i really do feel like I've retained a lot from these videos -- must be some of the best science/math explainers on youtube. Also sidenote it's a shame youtube trends have switched from breaking up videos to making one long one because they you never get the feeling of noticing a "part 12" pop up on the side and thinking "well. i've gotten this far. might as well keep going" and when you finally reach that one it's not even the last one.

  • @mathewleonlopez
    @mathewleonlopez 5 лет назад +1059

    Me: *hates math*
    Also me: *Watches this video because it was recommended*

  • @MartinMadsen92
    @MartinMadsen92 8 лет назад +14

    It's an (uncommon) misconception that Euler "didn't know what to do with negatives". Euler was the most productive mathematician to ever have lived. He dealt with complex numbers and complex functions in full generality, it is simply nonsense to say that he didn't know what to do with negative numbers. (It is true that he assigned negative values to some positive (divergent) series, but that was 100 % intentional.)

  • @jllebrun1
    @jllebrun1 8 лет назад +79

    52 years after studying the complex numbers in school, I finally understand complex numbers and more!!! Absolutely brilliant!!!! (I'll have to stop now or I'll wear out the keyboard unevenly - too many exclamations :)

    • @golinelli1
      @golinelli1 8 лет назад +9

      jllebrun1 same feeling but i'm 56!

    • @semphony100
      @semphony100 8 лет назад +13

      When i see wise people like you watching this and enjoying the beauty of acquiring a clarified version of old knowledge with such enthusiasm at such age, that sir makes me feel like who am I with 40+ age to feel down that I feel I wasted parts of my life not continuing to learn things I used to enjoy thinking that I am already old. Thank you sir for giving me hope that I am not alone at enjoying such knowledge. Thanks for sharing the passion to learn.

    • @pebblepod30
      @pebblepod30 7 лет назад +1

      Hossam Zayed
      Yeah I feel the same way Hossam, I have wasted parts of my life.

    • @TtttTt-ub5xb
      @TtttTt-ub5xb 7 лет назад

      Hossam Zayed
      حلو

    • @QsHsNation1
      @QsHsNation1 6 лет назад +1

      It's such a good feeling isin't it :)

  • @speedsystem4582
    @speedsystem4582 8 месяцев назад +1

    Here again, after a few years. Just wanted to let you know that, watching this was definitely one of the most memorable moments in my math journey. I got a whole lot more interested in Graphs and Complex Numbers, learnt to accept them as a concept that weirdly works.

  • @NeilSalemMAUSA
    @NeilSalemMAUSA 7 лет назад +61

    Great video!
    I think back to my years of college when I learned electrical engineering. We were buried in math every year: calculus, differential equations, differential equation with complex variables, and more. During most of those years, the square root of minus one was central to the math.
    Just days before my friends and I were to graduate, we were relaxing in the cafeteria drinking coffee, when one of my friends suddenly folded his arms and shook his head negatively left and right. "I don't care what they say," he said with a determined look on his face, "I will never believe in the square root of minus one!" We all laughed.

  • @masterhidsert1043
    @masterhidsert1043 8 лет назад +5

    I'm an engineering student so all of this is extremely interesting to me!! Instant sub! Phenomenal work.

  • @papaluskask999
    @papaluskask999 3 года назад +13

    Maths works really well in network analysers. In high frequency work, telecommunications industry etc. You have to work in 3 axis, frequency and time but also voltage

  • @DutchNorthAtlanticAlliance
    @DutchNorthAtlanticAlliance 2 года назад +1

    Including Workbook, including Solutions.. You are a true Math Hero!!! Even including Dutch subtitles for bonus comprehension!!! Impressive mate!!! Amazing work!!

  • @diamondblackford5048
    @diamondblackford5048 6 лет назад +5

    The word "lateral" explains everything!
    I hadn't been understanding "imaginary" numbers for years! You've discovered this secret for me. Thank you!

    • @bertrand3055
      @bertrand3055 5 лет назад

      i²=-1 démystifié :
      ruclips.net/video/2GwSUDm_Rg8/видео.htmlm43s

  • @JamesR624
    @JamesR624 4 года назад +117

    4:39-4:51 Ahh, of course.
    2 Apples - 3 Apples = 1 Microsoft.

    • @ultimatesans2175
      @ultimatesans2175 4 года назад +5

      You forgot to square the two terms on the left.

    • @Pushed2InsanityYT
      @Pushed2InsanityYT 4 года назад +4

      @@ultimatesans2175 then that would be a google

    • @piotrmachowski
      @piotrmachowski 4 года назад +1

      @@ultimatesans2175 Then it would be -5 (2^2-3^2=4-9)...

    • @ninjaslash52_98
      @ninjaslash52_98 3 года назад

      thank you now it makes sense

  • @AlexandraMiah
    @AlexandraMiah 5 лет назад +8

    i loved this video! normally i'm pretty slow at understanding these type of things but you made it real simple and enjoyable, thank you

  • @googleyoutubechannel8554
    @googleyoutubechannel8554 Год назад +1

    Alternately, a better way to think about it is that no mathematical systems are 'real' in that they are necessary to describe physical observations, they're all models we made up, imaginary numbers are just a useful extension to one system of math that allows us to describe a certain system of useful relationships a fairly compact way.

  • @joeirish1000
    @joeirish1000 9 лет назад +4

    Absolutely amazing. Great presentation, the best I've ever seen for a video about imaginary numbers and one of the best ever math videos.

  • @Dejawolfs
    @Dejawolfs 4 года назад +4

    this is truly why a lot of people find math difficult to understand. a lot of the names are grotesquely indescriptive. if they had more intuitive names, people would be able to pick things up much quicker, instead of having to first memorize what it means, in addition to learning how it works.

  • @datsmeyall
    @datsmeyall 4 года назад +48

    Fifteen years ago, little me would have been laughing to the thought of her grown self watching math-videos deep into the night

  • @krishnavekariya9534
    @krishnavekariya9534 3 года назад +2

    This video's title also had two part
    Real:What is imaginary number
    Imaginary:this series gone legendary

  • @takyc7883
    @takyc7883 4 года назад +5

    This comparison to negative numbers is actually so good

  • @shanamckay9258
    @shanamckay9258 7 лет назад +6

    I can't thank you enough for taking the time to make these imaginary numbers videos. We're about to start the topic in my applied Algebra 2 class, and it's always so hard for me to come across as fully believing in these things. I have been looking for a video like yours for a while. I may actually play them all! Really, this is just so awesome.

  • @dhruvshinde6089
    @dhruvshinde6089 5 лет назад +18

    Why the hell RUclips is recommending such an informative video after 4 whole good years?😯

  • @sunkruhmhalaci2592
    @sunkruhmhalaci2592 2 года назад

    This is the first time "imaginary numbers" (lateral is SO MUCH BETTER) have ever actually made sense to me in a physical context. Thank you.

  • @jcespinoza
    @jcespinoza 4 года назад +100

    3:41 I'm more concerned with what happened to Australia in this map

  • @mathmagic88
    @mathmagic88 4 года назад +15

    Hey, this is really cool. I love the animation for "lateral numbers". I have started seeing some of the impact of imaginary numbers watching 3b1b's series, but he just sort of travels around a unit circle with them. Lets see how the next videos in the series do.

  • @_Killkor
    @_Killkor 5 лет назад +220

    21st century: "let's call them fake numbers"
    22nd century: "flat numbers, because Earth is flat, so is everything"
    23rd century: "Numbers are individuals too! Each number should have a name! Isn't that right, Richard?; *-3:* _Yes._ "

    • @gdash6925
      @gdash6925 5 лет назад +7

      Every number has already an own name. So your theoretical statement makes no sense.

    • @fractal5764
      @fractal5764 5 лет назад +14

      25 Century: numbers get to choose their gender.

    • @_Killkor
      @_Killkor 5 лет назад +14

      @@gdash6925 No, my 3 is called Richard. Your 3 is called, I believe, Timothy. Your statement is so numberist.

    • @gdash6925
      @gdash6925 5 лет назад +3

      @@_Killkor my 69 is called..... wait

    • @want-diversecontent3887
      @want-diversecontent3887 4 года назад +1

      Microsoft Hites
      26 century: Numbers become humans.

  • @alialtica6791
    @alialtica6791 3 года назад +1

    As someone that still cannot understand imaginary number after 4 years of undergrad study, you put a relatable analogy with negative number. Now I understand why I need to understand it. Able to understand is a different topic.

  • @tibschris
    @tibschris 8 лет назад +290

    "Imaginary numbers are real"
    Oh u

    • @tibschris
      @tibschris 8 лет назад +31

      ***** I wonder if you understand humor...

    • @jcraig6431
      @jcraig6431 8 лет назад +5

      TootTootMcbumbersnazzle Of course the guy with the anime profile doesn't have a sense of humor while attempting, in vain, to be humorous himself.
      "oh u"

    • @bluedroid1541
      @bluedroid1541 7 лет назад +18

      That's the same as saying "There are more than two genders".

    • @tibschris
      @tibschris 7 лет назад +34

      Don't.

    • @reeshav4955
      @reeshav4955 7 лет назад +4

      whats wrong with anime -_-
      this aint an insult to math, dont get triggered

  • @frasafrase
    @frasafrase 9 лет назад +115

    What is that plot at 2:00? Because it has way more roots than it should.

    • @WelchLabsVideo
      @WelchLabsVideo  9 лет назад +75

      +Frasafrase Great question! I'll explain in detail as the series progresses, but yes, the function i show does have too many roots. This is because it's the only the real part of f(x) = x^2 +1 for complex x. In part 8 I'll show the real and imaginary parts together, and we'll see exactly 2 roots - I didn't want to overwhelm everyone in part 1. Thanks!

    • @thatsmath_yt
      @thatsmath_yt 9 лет назад +17

      +Frasafrase It's a consequence of 'graphing' a four dimensional relationship in three dimensions. Color weighting takes a bit of getting used to. Remember that mapping a complex number to a complex number (For example (3+2i)^2 = 5+12i) requires two dimensions for both the 'departure' and 'arrival' points.

    • @tibschris
      @tibschris 8 лет назад +2

      Only the "real" part of the graph is shown. In order to be a root, its real AND imaginary part (graph not shown) must intersect the y=0 plane. That only occurs at x=0+i and x=0-i, the two roots.
      Have a look at this plot. The two parts of the graph aren't shown together, but the roots are the values that overlap where the real "saddle" crosses the y=0 plane (two parabola shapes) and where the imaginary plot crosses y=0 (a cross-shape of points centered on the origin and aligned with the axes).
      www.wolframalpha.com/input/?i=plot+z%3D(x%2Biy)%5E2%2B1

    • @zinebzinouba2469
      @zinebzinouba2469 8 лет назад

      +Alan Mullenix how were they discob
      vered

    • @antoniolewis1016
      @antoniolewis1016 8 лет назад +1

      It's a plot of the real component of the complex function w=z^2+1
      Here, z is the "independent" complex number that used to be x and w is the "dependent" complex number that used to be y.
      The reason that this function seems to have many zeroes is that it's not looking at all of w, only the real part. If you looked for points which have zeroes in the real AND imaginary parts, you'd find there's only two of those.
      I have a strong feeling this didn't help much..

  • @Migueldeservantes
    @Migueldeservantes 8 лет назад +53

    I'm really interested to know how did he make that 2D graphic on to a 3D.. that was awesome...

    • @faizanm1563
      @faizanm1563 8 лет назад +6

      Migueldeservantes possibly wolfram alpha

    • @優さん-n7m
      @優さん-n7m 7 лет назад +19

      he is actually an alien. aliens have such advanced technology

    • @user-zu1ix3yq2w
      @user-zu1ix3yq2w 7 лет назад +2

      Migueldeservantes cunts never wanna give away their 'secrets'

    • @ns4k_tv
      @ns4k_tv 7 лет назад +4

      Probably after effects

    • @KittyGata314
      @KittyGata314 6 лет назад

      Migueldeservantes math :)

  • @adilisimon6184
    @adilisimon6184 9 месяцев назад

    Honestly this is the most important video out there explaining imaginary numbers. This has to be archived in museums for generations to come. Thank you very much for the important work!

  • @NourMuhammad
    @NourMuhammad 8 лет назад +6

    My subscription list has just earned a new Channel.
    Very nice illustration.

  • @planetmchanic6299
    @planetmchanic6299 4 года назад +7

    Here's the thing - add spin with leverage into these equations and you'll find gyrodesics. Temporal torsion in conserved momentum.
    I really like lateral. I'm voting for them in 2020. Go team.

  • @weili9349
    @weili9349 4 года назад +3

    1:47, it seems the solution to x^2+1=0 is a curve (or two) instead of 2 point (+i and -i). actually x is in 2 dimensional plane, so is f(x). so it requires 4 dimensional to show the function.

  • @IsomerSoma
    @IsomerSoma 10 месяцев назад +1

    This is the video that ignited great interesst in math in me for maybe the first time. As such it was a major contribution to why i am studying mathematics today. Thank you.

    • @the_linguist_ll
      @the_linguist_ll 4 месяца назад

      This an 3blue1brown’s video on the inscribed square problem for me (not pursuing math myself, but not because of a lack of interest)

  • @dalitas
    @dalitas 8 лет назад +87

    you should change the text of "0!" to just "0" or "0." since 0!=1

    • @WelchLabsVideo
      @WelchLabsVideo  8 лет назад +13

      Word.

    • @leonardoaielotassi1114
      @leonardoaielotassi1114 8 лет назад +3

      Welch Labs 0!=0, 1!=1, 2!=2, 3!=6; no?

    • @dalitas
      @dalitas 8 лет назад +30

      Leonardo Aielo Tassi nope, 0!=1
      One way of seeing it is by thinking that the factorial function tells us how we can order stuff, A&B can be ordered {AB} and {BA} 2!=2
      {A}gives just one "{A}" (1!=1)
      And the empty set { ø } can be ordered in one way {ø} 0!=1

    • @grahamlyons8522
      @grahamlyons8522 7 лет назад +7

      Dalitas D
      WOW! A totally unexpected but revelatory and logical answer.

    • @want-diversecontent3887
      @want-diversecontent3887 7 лет назад +1

      Graham Lyons
      x! = x * (x-1)!
      If 0! = 0
      Then
      1! = 1 * 0! = 1 * 0 = 0

  • @devhims
    @devhims 9 лет назад +9

    Mr. Welch, you have awesome presentation skills. Thanks for the video. :)

  • @timotheospetros
    @timotheospetros 8 лет назад +14

    Fantastic! Humorous, informative, brings further maths to life. I teach this subject, yet I've never once seen the graphic at 1:50 in any maths textbook.

  • @VoidHalo
    @VoidHalo 5 лет назад +5

    I'm largely self taught in anything beyond grade 8, so I didn't learn about complex numbers until I got into electrical engineering. Learning complex numbers in the context of a practical application like AC anaylsis helped them make a LOT more sense to me.
    It's too bad most students in school don't have that same benefit. I can't count how many times I stuggled to learn a math concept in school only to discount it as arbitrary nonsense because I couldn't understand it from the rote memorization way we were meant to learn. I find it much easier to learn something if I'm able to connect it to something useful or meaningful so I can understand it from an intuitive point of view, rather than just memorizing that this is how it works and taking their word for it.

    • @twentylush
      @twentylush 2 года назад +1

      Negative numbers have practical applications like debt, which is a concept that even pretty young kids are familiar with. Complex numbers and their practical applications are pretty tough to come by at the moment or become common very late in one's education, which I think contributes a lot to their un-intuitiveness. Complex numbers really do make AC analysis a lot easier to understand, much in the same way that negative numbers make debt easier to quantify. Same could be said about polar coordinates

    • @VoidHalo
      @VoidHalo 2 года назад

      @MikeProductions1000 I thought so, too. That's one of my favourite aspects of electronics is how often you come across topics which seem totally unrelated, but are closely linked in some very non-obvious way. The other part I like is just seeing all of these seemingly arbitrary concepts in math being put to practical use for the first time ever. Which goes for anything in engineering, really.

  • @justintyler4814
    @justintyler4814 3 года назад +3

    This stuff Really really helps me learn math. Even just reading this Gauss quote helps understanding something I really struggle with.

  • @julesverne6287
    @julesverne6287 9 лет назад +4

    1 minute in, can't wait for the next part!
    Nicely Done :D

  • @CellarDoor-rt8tt
    @CellarDoor-rt8tt Год назад +1

    One of the coolest parts of my abstract algebra class was when defining field extensions lead to a complete definition of the complex numbers in terms using field extensions on reals. I think what was so cool about this is that, if you look at how other numbers are proven to exist in the context of axiomatic set theory, numbers like the rationals are also defined as equivalence classes of naturals. This basically means if you accept the existence of rationals, you basically have to accept the existence of complex numbers

  • @ElVerdaderoAbejorro
    @ElVerdaderoAbejorro 7 лет назад +35

    "Numbers are lame. Let's invade something!" - LMAO! Subscribed! =D

  • @pewpewdragon4483
    @pewpewdragon4483 8 лет назад +9

    @5:15 we needed students to know things like negative numbers so they can understand what debt is

  • @weerobot
    @weerobot 5 лет назад +4

    Pulling that graph out of paper is Awesome...

  • @Anonymoususer6541
    @Anonymoususer6541 3 года назад +2

    Its in my recommendation..
    And i can surely say that i am not disappointed..👌👌👍👍

  • @Levfomin
    @Levfomin 4 года назад +6

    I could happily be studying for this now!

  • @GroovingPict
    @GroovingPict 8 лет назад +120

    When you "pull" the graph up and make it three dimensional, then yes it crosses the X axis, but it suddenly looks like it crosses it in a lot more places than just 2... and it should only be 2. So I dont think that 3d model was a good representation

    • @chocolatethunderific
      @chocolatethunderific 8 лет назад +5

      yeah, that's what i was thinking

    • @xheralt
      @xheralt 8 лет назад +63

      The actual function values would be the outermost edge of the shape, the actual extension of the plotted line, not the interior area. Which would be a _different_ but related function (probably involving calculus). It was filled in only to provide visual context for us viewers.

    • @johnstotz3800
      @johnstotz3800 8 лет назад +14

      Wait for the last part. He explains this specific issue.

    • @kuladeeparun
      @kuladeeparun 8 лет назад +3

      The exact point is mentioned in the workbook, take a look at it.

    • @nikhilprasad3947
      @nikhilprasad3947 8 лет назад +5

      Actually, this is a prank video by some jerk, cuz for the eq f(x)=x²+1, we are working with only 2 dimensions. Where the hell did you get the 3rd dimension from ? so for every question, just simply add another dimension if can't solve it?

  • @mwm48
    @mwm48 4 года назад +7

    At 5:20 - Negative numbers are absolutely connected to things in the real world, just look at my checking account.

    • @mwm48
      @mwm48 4 года назад +3

      I’m just joking, my entire checking account is imaginary.

  • @Apreche
    @Apreche Год назад

    I "learned" imaginary numbers at some point in school, very briefly. But I never truly understood them. You managed to do a better job in 5 minutes of RUclips video than 20+ years of education. Finally I truly get it, and it's not even hard. Completely demystified, like a great cloud has been lifted. You are a legend.

  • @hersirirminsul
    @hersirirminsul 5 лет назад +4

    Thank you so much! 'Imaginary' numbers were my big stumbling block in A level maths, and my maths teacher was unable to explain them (because he only got the job for being the headmaster's old chum). This video has a made it clear for the first time to me. If only my maths teacher had explained it as another dimension like this, instead of "You don't need to know how it works, just memorise how to use it to pass your exam". I might have passed that A level and become an astrophysicist as I wanted.

    • @tomjscott
      @tomjscott 3 года назад

      No, don't go there. You were a rational human being before when you couldn't understand imaginary numbers. You actually knew intuitively that it was all a load of garbage and just fantasy. Now you've come to accept them as real when they aren't. Go back to the light.

    • @epicmarschmallow5049
      @epicmarschmallow5049 Год назад

      ​@@tomjscott They're demonstrably real. Physicists have demonstrated that our most fundamental powerful theories of reality only work when using complex numbers. They're as real as any other number system; to assert otherwise is ignorance

  • @Tomyb15
    @Tomyb15 8 лет назад +16

    This video completely bought me. Guess I'm a sub now.

  • @MrPuff1026
    @MrPuff1026 8 лет назад +31

    1:54 OH! well that explains that! *goes to look in right dimension*

  • @MrJatinderseehra
    @MrJatinderseehra Год назад +1

    Thank you for this series, a really mind bogglingly "complex" topic beautifully and simply explained

  • @nouai
    @nouai 3 года назад +3

    I think the best way to describe the imaginary part is to imagine the world of forgotten things, when you found a thing, this means that it changed the state to real.

  • @IIRomoII
    @IIRomoII 6 лет назад +347

    I'm watching this for fun

    • @dragoncurveenthusiast
      @dragoncurveenthusiast 5 лет назад +4

      You are not alone :-)

    • @Matheus_Braz
      @Matheus_Braz 5 лет назад +27

      Dude I remember watching this video for the first time and understanding absolutely nothing of it. Now that I've had imaginary numbers and that stuff in school, I still don't understand it.

    • @slashlightning3261
      @slashlightning3261 5 лет назад +2

      @@Matheus_Braz same

    • @stanislaslaurent970
      @stanislaslaurent970 5 лет назад +6

      @@Matheus_Braz not gonna lie you got me in the first half

    • @christianjoseph6502
      @christianjoseph6502 5 лет назад +1

      I envy you dude I love math and i think it’s so fascinating but there’s just some parts of it that I do not understand

  • @MrJanes-cl5sj
    @MrJanes-cl5sj 4 года назад +56

    "why would we need a number for nothing?" LOL a mathematician with a sense of humour...whats that about.

    • @luskarian
      @luskarian 3 года назад +2

      Greek mathematicians murdered others for accepting the existence of fractions or something so

    • @Brawler_1337
      @Brawler_1337 3 года назад +7

      @@luskarian I thought that story was for the square root of 2 being irrational? Fractions were fine.

    • @motazfawzi2504
      @motazfawzi2504 3 года назад +1

      @@Brawler_1337
      Yeah it's kindof like that

    • @akshatmodi8607
      @akshatmodi8607 3 года назад

      @@luskarian It was Pythagoras who sentenced Hippasus to death by drowning for proving square root of 2 irrational

  • @vanshsingh7270
    @vanshsingh7270 3 года назад +2

    The best way to see is this .....
    For ancient people the negatives are imaginary because they were beyond there imagination. And for us imaginary (lateral) numbers are imaginary.....in future, people gonna make videos about us thinking that imaginary are imaginary...

  • @ernestboston7707
    @ernestboston7707 6 лет назад +26

    Ancient man had imaginary numbers.
    "how many unicorns do you have in your herd?"
    "i have -1"

  • @tranthaptinh
    @tranthaptinh 4 года назад +4

    I LIKE YOU I LIKE THE WAY GRAPHIC TO EXPLAIN ..... WHEN FIRST TIME LOOKING AT THE PICTURES OF YOUR MV AND WHEN I SEE YOU MOVING PICTURES ....... I HAVE SOME IDEAS UNDERSTANDING OF IMAGINARY NUMBERS IMMEDIATELY ................

  • @willywalter6366
    @willywalter6366 3 года назад +5

    AWESOME : Watched the whole serie! THIS was the best and most intuitive explanation of number theory and complex number ever, where also math newbies could follow and get a deep understanding! Thank you soo much was this highly entertaining and educative masterpiece! ❤️👍🏻💡 that was a tremendous effort of work and brain you put into it! 😇

  • @ablobofgarbage
    @ablobofgarbage Год назад

    I remember find this series years ago, it made me think of complex and imaginary numbers as completely natural and not strange at all, i want to thank you for being such a great teacher!

    • @WelchLabsVideo
      @WelchLabsVideo  Год назад +1

      Thank you!!

    • @ojkwame
      @ojkwame Год назад

      @@WelchLabsVideo Hello, please I think this is an amazing video but I would love if you could include the resources where you found all this info so people can do further reading . Thanks

  • @PauloSilva-zr8vk
    @PauloSilva-zr8vk 5 лет назад +204

    "Numbers are lame. Let's invade something!" Romans 3:50

    • @mryup6100
      @mryup6100 5 лет назад +14

      boi I thought that was a verse from the Bible lol

    • @andreaemanuele7293
      @andreaemanuele7293 4 года назад +3

      Absolutely loved that lol

    • @captainoblivious_yt
      @captainoblivious_yt 4 года назад +5

      @@mryup6100 That would be the Qu'ran.

    • @overlordprincekhan
      @overlordprincekhan 4 года назад +6

      @@captainoblivious_yt Research things before saying it in public or otherwise people will say you a dumb uneducated

    • @Acalmujannahmalaysia
      @Acalmujannahmalaysia 4 года назад +5

      @@captainoblivious_yt arrr... Swedenistan. Well, Islam developed the mathematic in the Goldena Age.