Why “probability of 0” does not mean “impossible” | Probabilities of probabilities, part 2

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  • เผยแพร่เมื่อ 28 ก.ย. 2024
  • An introduction to probability density functions
    Help fund future projects: / 3blue1brown
    An equally valuable form of support is to simply share some of the videos.
    Special thanks to these supporters: 3b1b.co/thanks
    Curious about measure theory? This does require some background in real analysis, but if you want to dig in, here is a textbook by the always-great Terence Tao.
    terrytao.files...
    Also, for the real analysis buffs among you, there was one statement I made in this video that is a rather nice puzzle. Namely, if the probabilities for each value in a given range (of the real number line) are all non-zero, no matter how small, their sum will be infinite. This isn't immediately obvious, given that you can have convergent sums of countable infinitely many values, but if you're up for it see if you can prove that the sum of any uncountable infinite collection of positive values must blow up to infinity.
    Thanks to these viewers for their contributions to translations
    Hebrew: Omer Tuchfeld
    ------------------
    These animations are largely made using manim, a scrappy open source python library: github.com/3b1...
    If you want to check it out, I feel compelled to warn you that it's not the most well-documented tool, and it has many other quirks you might expect in a library someone wrote with only their own use in mind.
    Music by Vincent Rubinetti.
    Download the music on Bandcamp:
    vincerubinetti...
    Stream the music on Spotify:
    open.spotify.c...
    If you want to contribute translated subtitles or to help review those that have already been made by others and need approval, you can click the gear icon in the video and go to subtitles/cc, then "add subtitles/cc". I really appreciate those who do this, as it helps make the lessons accessible to more people.
    ------------------
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ความคิดเห็น • 3.5K

  • @3blue1brown
    @3blue1brown  ปีที่แล้ว +1188

    If you're curious, I never ended up making the third part of this. Or rather, I made part of it and thought it wasn't very good. The plan is to put together something like a probability series this year, where the beta distribution will surely be one of the topics. Thank you for your patience!

    • @sw3aterCS_
      @sw3aterCS_ ปีที่แล้ว +29

      And thank you so much for your hard work!

    • @curiouslyglobal3538
      @curiouslyglobal3538 ปีที่แล้ว +24

      Thanks for the update. I will be waiting for it!

    • @bora6981
      @bora6981 ปีที่แล้ว +7

      3 hours ago wow thx man

    • @bacicinvatteneaca
      @bacicinvatteneaca ปีที่แล้ว +10

      3h ago? Is this being recommended to everyone all of a sudden?

    • @flipflipshift855
      @flipflipshift855 ปีที่แล้ว +11

      @@bacicinvatteneaca probably because someone recently donated a bunch of money in hopes of a part 3, so he felt some responsibility to clarify.

  • @3blue1brown
    @3blue1brown  4 ปีที่แล้ว +6234

    I have to imagine it's frustrating to follow this channel. I believe this is the third video in a row (excluding those on epidemics) that I ended by saying something like "we'll look at Bayesian updating in a continuous context in the next part". But whenever I think hard about the setup/prerequisite section of that video there's always something interesting enough to pull out to stand as its own video; there are just so many interesting topics here! Thanks for your patience, and hopefully, everyone gets that the goal here is to just hit as many fundamental ideas in probability as is reasonable.
    Also, in parallel with making these probability videos, I'll be trying a very different sort of experiment on the channel soon...stay tuned.

    • @michaelliu8887
      @michaelliu8887 4 ปีที่แล้ว +169

      It's fine because we still love your content

    • @itwasinthispositionerinoag7414
      @itwasinthispositionerinoag7414 4 ปีที่แล้ว +190

      if by frustrating you mean awesome then yes yes it is

    • @Mayaaahhhh
      @Mayaaahhhh 4 ปีที่แล้ว +51

      Even if we get left hanging sometimes, we still love to see all your videos and experiments :D

    • @ojotabe3
      @ojotabe3 4 ปีที่แล้ว +88

      Bro, frustrating is not a word I'd use to describe anything about this channel except my inability to fully grasp everything

    • @enthdegree
      @enthdegree 4 ปีที่แล้ว +3

      pls do a video on the difference between the questions that map and mle are answers to

  • @inordirectional
    @inordirectional 3 ปีที่แล้ว +246

    Mr. BlueBlueBlueBrown,
    Part three?
    Sincerely,
    Probability Stans Worldwide

    • @GammaFZ
      @GammaFZ 3 ปีที่แล้ว +9

      never knew his name was (Blue^3)Brown

    • @inordirectional
      @inordirectional 3 ปีที่แล้ว +4

      @@GammaFZ Now you know

    • @karapapaxatzidimitrakopoulos
      @karapapaxatzidimitrakopoulos 3 ปีที่แล้ว +4

      Mr. Blue+Blue+Blue+Brown

    • @kasskoulle
      @kasskoulle 3 ปีที่แล้ว +12

      Day 448: Still waiting.
      What do we do to get part blue of this?

    • @LiberOpine
      @LiberOpine 3 ปีที่แล้ว +1

      Mr. (Blue+Blue+Blue)(Brown)

  • @DaisyAjay
    @DaisyAjay 4 ปีที่แล้ว +8809

    "The probability of the dart hitting the board is 1". You obviously haven't seen me play darts.

    • @reinatr4848
      @reinatr4848 4 ปีที่แล้ว +155

      Or the wall

    • @____-ck1vp
      @____-ck1vp 4 ปีที่แล้ว +151

      Reinatr48 or the face

    • @jonidepp8797
      @jonidepp8797 4 ปีที่แล้ว +21

      nice one!

    • @xephyre6955
      @xephyre6955 4 ปีที่แล้ว +41

      Or the person.

    • @Leekodot15
      @Leekodot15 4 ปีที่แล้ว +51

      Or yourself.

  • @barney2159
    @barney2159 4 ปีที่แล้ว +3969

    Crush: You have 0% chance of being with me!
    Me: So you're telling me there's a chance?

    • @_kopcsi_
      @_kopcsi_ 4 ปีที่แล้ว +285

      no. there MIGHT be a chance, and NOT there IS. it’s a logical implication between the two statements (“0 probability” and “impossibility”), and there is a different relation between another two statements (“0 probability” and “possibility”). when you have impossibility, it must be an event with 0 probability. when you have an event with 0 probability, you might have possibility and impossibility as well. all of this is due to our mathematical toolset’s limitations (infinitesimals are treated as zero). that’s why there are extensions in mathematics which can handle these situations better (e.g. hyper-real numbers where infinitesimals are not zero anymore). but when we have this ambiguity due to this kind of limitation, a “meta-probability” level emerges, since you can have possibility or impossibility when you deal with an event with 0 probability. this is a meta-possibility.
      ps.: well, by the end of my comment I realised that you were technically correct, since there is no difference between “existence of chance” and “possibility of chance”.

    • @thatoneguy9582
      @thatoneguy9582 4 ปีที่แล้ว +289

      k0p1k4
      alright slow down Socrates

    • @ultimaxkom8728
      @ultimaxkom8728 4 ปีที่แล้ว +108

      @@_kopcsi_ _"ps.: well, by the end of my comment I realised that you were technically correct, since there is no difference between “existence of chance” and “possibility of chance”."_
      This is so sad... Can we hit 1 million likes?

    • @AbhishekSharmahehe
      @AbhishekSharmahehe 4 ปีที่แล้ว +25

      Well,there might be a chance of chance .

    • @luna010
      @luna010 4 ปีที่แล้ว +13

      @Angel Yotov
      No; being with me or not being with me is binary and not continuous so if being with me is 0% the only other possibility which is not being with me would be 100%. “There’s a 0% chance that there’s a 100% chance of you being with me” would be a better example.

  • @shayanpoordian5986
    @shayanpoordian5986 4 ปีที่แล้ว +386

    When I was trying to learn linear algebra, you put out a series solving all my confusion. then when I got interested in neural networks you put out a series which made me dive deeper and end up trying to learn stats. then you put a series on stats.

    • @shakiwizao
      @shakiwizao 4 ปีที่แล้ว +15

      Shayan Poordian Oh man, it went the exact same way for me. Started the engineering grad and the Calc/Algebra ones were fundamental to my success. Then the Diferential Equations series and now that I'm into data analysis, stats. God knows how much I love this channel :D

    • @arpitdas4263
      @arpitdas4263 4 ปีที่แล้ว +4

      You're a lucky one. I still dream of that elliptic curves video

    • @gattungswesen1630
      @gattungswesen1630 4 ปีที่แล้ว +3

      Grant Sanderson really is the gift that keeps on giving.

    • @Aldrnari
      @Aldrnari 4 ปีที่แล้ว

      I kind of went from the other direction: From studying statistical science, I started branching off into more traditional mathematics, like linear algebra. His series on linear algebra is also what brought me to the channel. And I'm thrilled that he's branching into stats/probability/data science, because that's my wheelhouse.

    • @Lucky10279
      @Lucky10279 4 ปีที่แล้ว +2

      @@Aldrnari His linear algebra series is quite helpful. His video on change of basis in particular is what made that concept _finally_ make sense to me. I really liked his analogy to two people choosing two different vectors as their basis and then making it into a puzzle of how to translate between the two different reference frames.

  • @shakofarhad876
    @shakofarhad876 4 ปีที่แล้ว +793

    Just a former maths teacher talking into the internet void about probability:
    To me it makes sense that the dart has a probability of 0 of hitting a specific point on the dart board. If you are aiming at a specific point, it means that you are betting on the fact that your accuracy will be on the level of atoms, and even smaller (because math has no Planck length). You literally are boasting infinite accuracy, which is impossible. That is why your probability of hitting that specific point is 0. But if you say "I am going to hit Bullseye". Then things change, now you are being reasonable. The bet is no longer on hitting the infinitely small point, but rather hitting an area which contains infinitely many of these infinitely small points. In some sense you have infinitely higher probability now since you have infinitely many small points. But of course in our real world we have the Planck length which means that we are never really talking about infinity, just very big or very small numbers. That also means that the probability is never truly 0, however it is extremely tiny. ^^

    • @WolfrostWasTaken
      @WolfrostWasTaken 4 ปีที่แล้ว +42

      This comment deserves more likes. It made me understand the matter at hand even more. Props!

    • @jesusvera7941
      @jesusvera7941 4 ปีที่แล้ว +4

      oh, so thats what he said? pretty obvious

    • @flyingface
      @flyingface 4 ปีที่แล้ว +37

      Nice analogy
      But I think you're somewhat conflating physics with math here

    • @nanigopalsaha2408
      @nanigopalsaha2408 4 ปีที่แล้ว +15

      Well in fact we don't even know whether Planck length is the smallest unit of length. We *think* so. There is no proof of this.

    • @zakthesquirrel7621
      @zakthesquirrel7621 4 ปีที่แล้ว +8

      what if we use a plank length dart ?

  • @leftfootfirstpolitics
    @leftfootfirstpolitics 4 ปีที่แล้ว +146

    8:38 probability the dart hits somewhere on the board is 1
    With my throwing arm, that's pretty generous...

    • @trickygamer555
      @trickygamer555 4 ปีที่แล้ว +9

      me: (misses something literally next to me)
      also me: I blame quantum physics and whatever things are unexplained.

  • @thetophatgentleman4634
    @thetophatgentleman4634 4 ปีที่แล้ว +5636

    My friend trying to comfort there is a chance of me getting a girlfriend.

    • @cifar10
      @cifar10 4 ปีที่แล้ว +941

      Girlfriends are discrete objects, and in a discrete setting, a probability of zero still always means it is impossible.
      Sorry bud

    • @er.you2594
      @er.you2594 4 ปีที่แล้ว +35

      lol

    • @NovaWarrior77
      @NovaWarrior77 4 ปีที่แล้ว +234

      @@cifar10 why'd you have to hurt us this way???

    • @NovaWarrior77
      @NovaWarrior77 4 ปีที่แล้ว +61

      Don't worry man, girls love top-hatted gentlemen.

    • @Arya-sm5jx
      @Arya-sm5jx 4 ปีที่แล้ว +82

      @@NovaWarrior77 as a girl I can confirm this

  • @JetFalcon710
    @JetFalcon710 2 ปีที่แล้ว +23

    8:31 That reminds me of one of Zeno's paradoxes, where he says that one grain of mullet falling does not make a sound, but a thousand grains falling does make a sound, seemingly showing that many nothings somehow make something

    • @emmawatson9180
      @emmawatson9180 2 ปีที่แล้ว

      Nice

    • @NoriMori1992
      @NoriMori1992 2 ปีที่แล้ว +7

      Sometimes I wonder how Zeno managed to get through life, given how often he thought about the seeming impossibility of iterating a bunch of small things into one big thing.

    • @mieszkogulinski168
      @mieszkogulinski168 2 ปีที่แล้ว +1

      @@NoriMori1992 Or he was just a troll

  • @josephv4174
    @josephv4174 4 ปีที่แล้ว +444

    3b1b, How about taking consideration on making *"Essence of Number Theory"* ? Much respect!

    • @Nylspider
      @Nylspider 4 ปีที่แล้ว +12

      I would love that tbh

    • @varunraju1569
      @varunraju1569 4 ปีที่แล้ว +28

      That would be amazing, but is there much scope for visualization?

    • @sohampatil6539
      @sohampatil6539 4 ปีที่แล้ว +1

      Yes great idea

    • @infinitymatrix2890
      @infinitymatrix2890 4 ปีที่แล้ว

      That would be really cool

    • @winoo1967
      @winoo1967 4 ปีที่แล้ว

      This is a great idea!! I intend on presenting myself to the math Spanish olympiad next year, and it would be really useful

  • @kelly4187
    @kelly4187 3 ปีที่แล้ว +30

    I'd love to see the third video in this three part series when it is ready! You've done a great job setting the scene. If I had explanations and graphics like this on my statistics MSc it would have been much smoother!

  • @magnuseifr
    @magnuseifr 4 ปีที่แล้ว +170

    1:31 that's some sneaky famous constants right there

    • @jpe1
      @jpe1 4 ปีที่แล้ว +13

      Magnus Eide-Fredriksen Easter Eggs in a video released on Easter... who woulda thunk 😀

    • @GeeTransit
      @GeeTransit 4 ปีที่แล้ว +3

      @@grammarnazi9456 *thunk*

    • @thorr18BEM
      @thorr18BEM 4 ปีที่แล้ว +1

      Denislav Ivanov , if you don't like colloquialism, then why not also correct the use of *woulda* which is obviously actually *would'a*, a corruption of *would've*, a contraction of *would have*? Why would it be OK to corrupt one word but not the other?

    • @squibble311
      @squibble311 4 ปีที่แล้ว +1

      π e δ φ

    • @nostalgiafactor733
      @nostalgiafactor733 4 ปีที่แล้ว

      I don't get it? please explain. I don't see Pi, e, etc.

  • @lucaslucas191202
    @lucaslucas191202 3 ปีที่แล้ว +9

    1:55 I think this 'paradox' is a good example of what infinitesimals can be useful to describe. A value which added together infinitely many times gives something finite. It's a concept that is hard to understand but is clearly a thing for these sorts of concepts. Not that it gives a useful value, but it's a useful concept to understand this.

  • @johnchessant3012
    @johnchessant3012 4 ปีที่แล้ว +46

    I just re-watched the "divergence and curl" video and now I can't stop thinking about how the factory at 2:25 has positive div.

  • @666MrGamer
    @666MrGamer 2 ปีที่แล้ว +80

    Hey Grant! This video is amazing. I was wondering if this series would ever come to and end with the third part with beta distributions? I am really curious. Thank you for your great work!

  • @CaptainSpock1701
    @CaptainSpock1701 4 ปีที่แล้ว +35

    5:26 - And here I was looking for Acrobat Reader every time I saw a PDF?

  • @DJStompZone
    @DJStompZone 4 ปีที่แล้ว +1

    (Partially in response to the pinned comment by OP)
    Can we all stop and thank and/or applaud 3Blue1Brown for the lack of sponsored content? I really appreciate the integrity and the obvious desire to drive the channel in an "educational over commercial" direction. Regardless of anything else, it's a very entertaining channel and I, for one, greatly appreciate the purism and consistancy.
    *Steps down off of my soapbox*

  • @infinitepower7298
    @infinitepower7298 ปีที่แล้ว +5

    should i say : the probability to see part 3 tends to zero ?

  • @thelolminecrafter7830
    @thelolminecrafter7830 4 ปีที่แล้ว +9

    When you started explaining about how we should view *h* as ranges, my mind immediately tried integrating the function P(P(h)).
    I'm starting to get worried that I've been studying Calculus for way too long.

  • @pedrorrivero
    @pedrorrivero ปีที่แล้ว +50

    When will we get the next and final chapter to this awesome series? 🙃 keep coming back hoping to find it haha

    • @jasonremy1627
      @jasonremy1627 ปีที่แล้ว +7

      I know. Just had the same thought myself!

  • @JohnDoe-ki6yd
    @JohnDoe-ki6yd 4 ปีที่แล้ว +31

    If they can't be nonzero, and they can't be zero, we simply extend the problem to the surreals and make them equal to the infinitesimal times a scalar, so they all add up to one.

    • @revenevan11
      @revenevan11 4 ปีที่แล้ว +1

      Yes! I love this way to explain/express this using surreal numbers! Thank you so much, I'm going to cite this example from now on when questioned on the "usefullness" of surreal numbers.

    • @tejing2001
      @tejing2001 4 ปีที่แล้ว +2

      @Jake P Technically there are multiple different hyperreal number sets, of which the surreals are the largest (though the surreals are a proper class, not a set, but I'm getting off topic now). However, any of them should allow this. The differences between them don't really come up so long as you're using them for calculus.

    • @mbrusyda9437
      @mbrusyda9437 4 ปีที่แล้ว

      @@modnarsarhp it does have a value, zero is the value

    • @mbrusyda9437
      @mbrusyda9437 4 ปีที่แล้ว

      @@modnarsarhp no, I mean the value is zero, not some small nonzero number

    • @JohnDoe-ki6yd
      @JohnDoe-ki6yd 4 ปีที่แล้ว

      @@tejing2001 Do you know of an example of a person calculating Bayesian probability using this approach? I'm very interested in it, but don't really know where to start.

  • @dimka_sh
    @dimka_sh 2 ปีที่แล้ว +3

    Still waiting fo 3rd part(

  • @chetanyamishra2916
    @chetanyamishra2916 2 ปีที่แล้ว +1

    man you know this video is incredibly useful for understanding maxwells speed distribution in KTG if you just relate it and that's the one thing I adore about this video thanks grant🙏

  • @danielescotece7144
    @danielescotece7144 4 ปีที่แล้ว +24

    Have not seen it yet but I know this video is gonna be good "almost surely"!

  • @PeregrineBF
    @PeregrineBF 4 ปีที่แล้ว +8

    "...Well even if that probability was minuscule, adding them all up to get the total probability of any one of these values will blow up to infinity."
    Applies over the Reals (and thus over the rationals, etc). But it doesn't apply over the Surreal Numbers, or any other ordered field with infinitesimals like the Hyperreals. For example, {1, 2, 3, 4, ... |} * {0 | 1, 1/2, 1/4, 1/8, ...} = 1 (in any set theory which permits transfinite induction up to $S_{\omega^2}$).
    Given the passing of Conway it might be nice to do a video on the Surreals. They're one of his lesser known but more interesting constructs, though the Hyperreals are a more popular way to get the same results (they're isomorphic to the Surreals if the Axiom of Global Choice is accepted). But I find the Surreals to have a far more intuitive construction than the Ultrapower Construction of the Hyperreals.
    Edit: After finishing the video, of course model theory is brought up. That's very closely related to nonstandard analysis, which uses the hyperreal numbers.

    • @gaboqv
      @gaboqv 4 ปีที่แล้ว

      where di he talk about model theory?

  • @_wetmath_
    @_wetmath_ 4 ปีที่แล้ว +17

    5:26 show this to someone without context

  • @mihirkolli9509
    @mihirkolli9509 2 ปีที่แล้ว +1

    Crazy, I just took my econometrics final on exactly this topic: random variables, sample distribution, measure theory, and next time I check my TH-cam home page I see this video !

  • @PP-im6lu
    @PP-im6lu 5 วันที่ผ่านมา

    It's a pity that Part 3 is still missing. Recently, I've had to learn about beta distribution for my job so I watched videos from other channels and I think I've got it now. But I would still like to see how this channel will explain the topic, because I have learned so much from you in the past few years!

  • @zizo-ve8ib
    @zizo-ve8ib ปีที่แล้ว +6

    Just HOW DID THIS MAN LEARN MATHS, I'm literally dying to know, it's my ultimate dream to learn math concepts as he puts it in his videos, his videos and Khan academy's are what truely got me to love maths

    • @akaimizu9780
      @akaimizu9780 ปีที่แล้ว

      You go to university?

    • @zizo-ve8ib
      @zizo-ve8ib ปีที่แล้ว +3

      @@akaimizu9780 unfortunately yes I'm an engineering student studying communications engineering 3rd year and this guy explains math in a way no teacher or professor I've ever heard of did (nor in any other subject)

    • @kinghassy334
      @kinghassy334 ปีที่แล้ว

      @@zizo-ve8ib take a probability and stochastic process course

    • @zizo-ve8ib
      @zizo-ve8ib ปีที่แล้ว

      @@kinghassy334 I did take such a course, though not complete, but problems started from correlations, auto correlation and cross correlation and such

    • @blagojestojsavljevic671
      @blagojestojsavljevic671 ปีที่แล้ว +2

      @@zizo-ve8ib well you have to take into consideration that this isnt done in one sitting, its research materials multiple takes, writing and perfecting script.
      its harder for teachers to have that kind of script when you are working with live audience that has questions. also its almost impossible (probability of 0) for someone to talk like this of the top of his head

  • @huyvuquang2041
    @huyvuquang2041 ปีที่แล้ว +1

    In case you forget, we're still waiting for the next part :)))
    Anyway, ty for great content

  • @yoursole6817
    @yoursole6817 2 ปีที่แล้ว +3

    I see what you did there with the decimals at 1:47 :D

  • @angelajcabul3165
    @angelajcabul3165 2 ปีที่แล้ว +1

    I need the part 3, excelent videos!

  • @qmmav697
    @qmmav697 ปีที่แล้ว +7

    This series is great. (As are all your other videos). I am a big fan of your work. I am looking forward to the next part on probabilities of probabilities, especially on the beta distribution. No pressure, take your time :). But, as it has been several years now, do you intend on continuing this series at all, or is it stopped? Once again no pressure, just wondering because it looks like you have moved to something else (which is also great).

  • @GenericInternetter
    @GenericInternetter 4 ปีที่แล้ว +12

    2:05 the way i see it, the probability of any of those values is not 0. It’s an infinitesimal (1/inf). Something that exists but with an infinitely small value is not the same as it not existing at all.
    For example the probability of the value being 0.70001 is (1/inf), but the probability of the value being 2.0 is 0, because it can never ever be that value.
    So if there’s an infinite number of possible values from 0.0 to 1.0, each at (1/inf), then you get
    (inf x 1/inf) = 1
    As i said, that’s just the way i see it, and it makes sense.

    • @sjiht0019
      @sjiht0019 4 ปีที่แล้ว +6

      That doesn't work unfortunately. This is because between every two different numbers there an infinite amount of numbers, not just between 0.0 and 1.0. So for example if you split it in half then the amount of numbers between 0.0 and 0.5 is inf. Each of those number would have a chance of 1/inf so the chance of a random being between 0.0 and 0.5 would be inf * 1/inf = 1. The problem is that the same would hold for the numbers between 0.5 and 1.0. So you would have a chance of 1 of being below 0.5 but also a chance of 1 of being above 0.5. So as you can see it leads to a contradiction.

    • @adheensheikh6896
      @adheensheikh6896 4 ปีที่แล้ว

      Generic Internetter Exactly! I agree with you 100% When he's adding the zeros he takes the sum to be zero as if we're adding finitely many of them but we have an infinite number of zeros to add and that means recourse must be had to the theory of infinitesimals

    • @sams6454
      @sams6454 4 ปีที่แล้ว +1

      @@sjiht0019 Also note that a sum of infinitely many numbers is not necessarily infinity, but a sum of an *uncountable* number of positive numbers is infinity.

    • @petrie911
      @petrie911 4 ปีที่แล้ว +1

      @@sjiht0019 You assume inf/2 = inf. This isn't true in non-standard analysis, which is the rigorous way of treating the infinitesimals the OP is getting at.

    • @technoultimategaming2999
      @technoultimategaming2999 4 ปีที่แล้ว +1

      @@sjiht0019
      Also, if it is the first number above 0, you would have to go through an infinite amount of 0.
      For example
      0.00... = 0

  • @govamurali2309
    @govamurali2309 3 ปีที่แล้ว +5

    Waiting for part 3 and 4!!!🥰

  • @TheSummoner
    @TheSummoner 4 ปีที่แล้ว +5

    5:16 - Nice Euclid’s Orchard :D

    • @lukarikid9001
      @lukarikid9001 4 ปีที่แล้ว +2

      Urizen i always remember when my family went on road trips through long highways, there were tons of orchards. When the little sticks holding the saplings up moved past, it created a very similar effect. Cool to know that it has a name!

  • @tahamagdy4932
    @tahamagdy4932 2 ปีที่แล้ว +1

    I am impatiently waiting for the rest videos.

  • @DockedSlinky
    @DockedSlinky 4 ปีที่แล้ว

    Your job seems awesome. You get to make videos for others to learn while going really in depth and learning a lot. That’s the dream

  • @aditimuthkhod1252
    @aditimuthkhod1252 4 ปีที่แล้ว +1

    I think about this as: when we use 1 dimension to denote the probability, as the probability gets smaller and smaller it becomes zero, but if we use 2 dimensions or more, the area becomes zero, yes, but we still have one dimension that's not zero, i.e. the height.
    I guess that's why we look at the (radial) probability density of an electron around the nucleus
    I finally know why, after 2 years of believing there's some high level science behind it, that's out of my reach! Thanks, thanks a lot 😭🙏🏻

  • @playlist2652
    @playlist2652 3 ปีที่แล้ว +4

    These are awesome - is Part 3 ever gonna drop?!

    • @jayd2279
      @jayd2279 3 ปีที่แล้ว

      since the release of this video, there's been a 0% chance of it being finished on a given second, so possibly not

  • @mattiasselin4955
    @mattiasselin4955 ปีที่แล้ว +3

    You're awesome! Please let us have part 3 ❤

  • @jean-baptiste6479
    @jean-baptiste6479 4 ปีที่แล้ว +1

    What is the probability to choose a random real number, for example 0 or 1?
    Is it possible to choose a random real number (?) Two levels of difficulty:
    1-in such a way that any number can theoretically be chosen?
    2- with an equal probability for each real number?
    This melts my mind.

  • @auriakamal9551
    @auriakamal9551 2 ปีที่แล้ว +3

    This is a good opportunity to use 3b1b's videos to calculate the probability of us 100% getting a part 3 to this video

  • @DGman4
    @DGman4 4 ปีที่แล้ว

    I think it may be easier for people to understand if they consider what it even means to specify the number of interest. This comes down to significant figures. When one says 70% probability, what really is meant is 70% +/- 0.5%, or 70.0 +/- 0.05%, or 70.00 +/- 0.005%. At some point there is a limited degree of precision expected, because they probably aren't asking for the difference in likelihood of the probability being 70.0000000000% versus 70.0000000001%. Thus when it is asked what the probability of the probability being 70% is, what is really being asked is what the probability of the probability being within some expected tolerance of 70%, which ties directly into the concept of integrating over a probability density function.

  • @KipIngram
    @KipIngram 3 ปีที่แล้ว +3

    You know, it really seems to me like this should be taught *starting* with PDFs. Then you introduce discrete probabilities as just slicing up the PDF into a set of ranges, and you're done. Just seems to make more intuitive sense that way - it's strongly intuitive visually how you're making that step from continuous to discrete.

  • @ryangraham6878
    @ryangraham6878 ปีที่แล้ว

    The first minute of this video explained the Hilbert hotel paradox for me.

  • @sofiazulfan9938
    @sofiazulfan9938 ปีที่แล้ว

    math is not too difficult, teaching math is a different story (very HARD) thanks to you. 3b1b

  • @tombnomb2938
    @tombnomb2938 4 ปีที่แล้ว +8

    lol I understood nothing but he has a calming voice so it's all good

  • @HxTurtle
    @HxTurtle 2 ปีที่แล้ว

    the car factory's name changed, lol. I prolly only noticed because my brain was like, "okay, I won't be able to follow along the actual content so maybe I find something else that doesn't blow my mind." 😂

  • @periodictable118
    @periodictable118 11 หลายเดือนก่อน

    All of this goes to say 0*infinity can equal anything, and is intuitively the reason that limits in form 0/0 or 0*infinity are indeterminate, and you can get cases where 0*inf = 0, 0*inf = any positive real number, and 0*inf = infinity.

  • @matthewocadiz7333
    @matthewocadiz7333 3 ปีที่แล้ว

    How long did it take you to animate all those little arrows at 5:14-5:16. Such a small detail but I appreciate it lol. I mean I can’t imagine what kinda work gets put into these videos but then to just take to time to sprinkle in nice little details like that. Its more than we deserve...

  • @felixisaac
    @felixisaac 4 ปีที่แล้ว +7

    Next episode; "Accuracies of accuracies"

  • @taleladar
    @taleladar 3 ปีที่แล้ว

    The paradox introduced can be thought of by thinking of an exact value as an *infinitesimally small* slice. It's not simply 0, which would result in adding up a bunch of zeros to get nothing, and it's not a conventional "non-zero number" which would result in an infinite area. As it turns out, adding up an infinite amount of infinitely small pieces (which is commonly estimated in calculus) can sum up to a finite number.

  • @hkm239
    @hkm239 4 ปีที่แล้ว +57

    My probability of getting a girlfriend is zero....
    So I still have a chance

    • @atifadib
      @atifadib 4 ปีที่แล้ว +7

      that's a discrete scenario my friend, so i guess you don't have a chance :)

    • @GeeTransit
      @GeeTransit 4 ปีที่แล้ว +3

      th-cam.com/video/ZA4JkHKZM50/w-d-xo.html&lc=UgzPdzTFR_flYoo0fXZ4AaABAg
      see this man's reply

    • @amarilloatacama4997
      @amarilloatacama4997 4 ปีที่แล้ว +2

      You still have a chance, but only if she has measure zero

    • @RazorM97
      @RazorM97 4 ปีที่แล้ว

      "so you're telling me there's a chance"

    • @MrCmon113
      @MrCmon113 4 ปีที่แล้ว

      No, because you getting a girlfriend is not one possible future out of all possible futures, but an uncountable set of possible futures, whose probability is still zero. The probability of every future in which you don't have a girlfriend is zero, but one of them will occur.

  • @pieterboelen2862
    @pieterboelen2862 2 ปีที่แล้ว +1

    Except a probability of zero DOES mean "impossible".
    That's the whole definition.
    Making your bars infinitely narrow doesn't give them a probability of zero.
    It reduces your ranges to something meaningless.
    A line is simply something different from a surface.

  • @aero_singh
    @aero_singh 4 ปีที่แล้ว +9

    Me before exam: Finally, prepared probability for maths exam.
    Same me after watching this video: pencho, kuch nhi aata probability ka

  • @0bada905
    @0bada905 4 ปีที่แล้ว +7

    You didn't put in mind that when you flip a coin, it can land vertically :D

    • @deemcgann1695
      @deemcgann1695 4 ปีที่แล้ว +2

      Yeah but that will never happen
      ...
      Wait

    • @aphraxiaojun1145
      @aphraxiaojun1145 3 ปีที่แล้ว +1

      Yesnt going to happen man

  • @ashishlukka
    @ashishlukka 2 ปีที่แล้ว

    "Possiblity is better tied to proabability density rather than probability" sentence with high impact.

  • @NoahBaier
    @NoahBaier ปีที่แล้ว +1

    It’s so sad there is no part 3 yet :(

  • @maxlovell
    @maxlovell ปีที่แล้ว

    Love your videos, you've saved me many a time! Would really appreciate part 3 about now, if you can!

  • @noincognito1903
    @noincognito1903 3 ปีที่แล้ว

    3Blue1Brown: 2:16
    Zeno: Write that down!

  • @manuelhexe
    @manuelhexe 2 ปีที่แล้ว +1

    You make my head exploding 🤯

  • @jay_sensz
    @jay_sensz 4 ปีที่แล้ว +6

    1:52 ...I'm pretty sure using the Σ notation to denote summation over an uncountably infinite set is illegal D:

    • @TheArbieo
      @TheArbieo 4 ปีที่แล้ว

      Yuuuup, this rubbed me the wrong way too. Using logic similar to what is employed here it's easy to make a 1 = 0 proof.

    • @number_8903
      @number_8903 3 ปีที่แล้ว

      What but they use it all the time in high school

  • @aporifera
    @aporifera 4 ปีที่แล้ว

    perfect video to watch for students starting to learn integration

  • @sohamshah5572
    @sohamshah5572 3 ปีที่แล้ว +1

    Haha, tiny brown pi at 8:26 symbolizing you.
    Of course, then we have pi at 0:17

  • @GuyMahoney
    @GuyMahoney ปีที่แล้ว

    A lot of problems in maths seem to come about from entertaining infinitely divisible reality, which is neatly dealt with in reality by having a smallest size of reality.

  • @OmarGonzalez-tg9uv
    @OmarGonzalez-tg9uv 3 ปีที่แล้ว +1

    I think the probability of p(0.7) being 0 is just misleading.
    When you demonstrate the bar distribution, it is clear that the probability (in a uniform distribution example) would be 1 / x, where x is the number of divisions. As x gets bigger, the probability gets smaller. One is tempted to quickly say that as x becomes infinity, the probability becomes 0, BUT that's where the intuition problem begins.
    In reality, since as x gets bigger, the probability gets smaller, that means that no matter how big x is, the probability will never be 0. This is obvious since if your 0 means 'nothing' then by increasing x you would obtain a probability smaller than nothing which is not possible. In other words, 0 is not "nothing" in this context, but rather, an infinitely small number (to match x, an infinitely big one).
    Once you have that realization, you can tell that the sum of the individual probabilities is not 0 * inf, but simply (1/inf)*inf. Usually this type of operation has no defined answer, but since we know our "0" came from that very same number of divisions, it is clear the answer is 1

  • @mathguy37
    @mathguy37 2 ปีที่แล้ว

    Wow part 3 is really cool

  • @jonpeters9604
    @jonpeters9604 2 ปีที่แล้ว +1

    I cried when I switched my major to stats and went to class and it was all calculus..

  • @PapaFlammy69
    @PapaFlammy69 4 ปีที่แล้ว +4

    bruh

  • @mohamedjawadaatafay5268
    @mohamedjawadaatafay5268 4 ปีที่แล้ว

    A problem with the logic in 2:00, the sum of infinite amount of numbers is NOT always Infinite, and in some cases it can be calculated, for example the sum of an infinite geometric serie can be determined.

  • @mariebcfhs9491
    @mariebcfhs9491 8 หลายเดือนก่อน

    The point of the dart is not an infinitesimal point. It has an area no matter how small. And so the question of the probability of a dart hitting any "point" on the board should be what is the probability of the dart point's area being contained in the area on the dart board.

  • @antoniofernando967
    @antoniofernando967 3 ปีที่แล้ว +6

    My boy Dream be like:

  • @arsilvyfish11
    @arsilvyfish11 2 ปีที่แล้ว

    Petition to get the 3rd part of this series from Grant!

  • @void2258
    @void2258 3 ปีที่แล้ว

    I wish at some point you would made some videos on Lebesgue Integration since it keeps being mentioned.

  • @bloemundude
    @bloemundude 4 ปีที่แล้ว +1

    There is a huge difference between "equals zero" and "approaches zero". You might want to be more careful about which you mean at many of the points you used them.

  • @adamardiansyah6680
    @adamardiansyah6680 3 ปีที่แล้ว +3

    has the third video comes out?

  • @macornman
    @macornman 3 ปีที่แล้ว

    A very similar issue comes up in quantum mechanics. Like with energy density and the ultraviolet catastrophe

  • @saqibjawed4444
    @saqibjawed4444 3 ปีที่แล้ว +3

    where is the next part of video

    • @andreykey2623
      @andreykey2623 3 ปีที่แล้ว

      Really

    • @EB3103
      @EB3103 3 ปีที่แล้ว

      tell us if you found it please

  • @adamrobinson6951
    @adamrobinson6951 4 ปีที่แล้ว

    The easiest way I can rationalise this in my head is as follows: The odds of h being exactly equal to any given value are infinitely small (0). However, there are infinite potential values of h. We are used to being able to total the probabilities of some real number of potential outcomes to 1, but we don't have a real number of possible outcomes.
    Essentially, we are asking what zero multiplied by infinity equals, and that's an illogical question.
    0*∞=n
    ∴ ∞ = n/0, which is illogical

  • @glennyurchenko6381
    @glennyurchenko6381 4 ปีที่แล้ว

    almost struck a reward worthy topic

  • @navalism
    @navalism 4 ปีที่แล้ว +8

    I just hope your prediction of 10M cases by Apr 22nd doesn't come true.

    • @3blue1brown
      @3blue1brown  4 ปีที่แล้ว +9

      The number of recorded cases stopped following an exponential a couple weeks ago.

    • @personzorz
      @personzorz 4 ปีที่แล้ว +2

      @@3blue1brown but test capacity stopped increasing a while ago too. Going by established death rates and infection to death delays, there's probably at least 5 million infected in the USA

  • @mesplin3
    @mesplin3 4 ปีที่แล้ว

    The infinitely precise dart can hit (0.000001 , 0.23) because (0.000001 , 0.23) is an element of the set of points the dart can hit, and the derivative is the instantaneous rate of change.

  • @nickadams2361
    @nickadams2361 2 ปีที่แล้ว

    dude thank u for these videos you have covered so damn much

  • @juicebox11598
    @juicebox11598 ปีที่แล้ว

    I absolutely love your videos

  • @armorelarmadura7807
    @armorelarmadura7807 ปีที่แล้ว +1

    Isn't the probability technically a limit approaching zero rather than actually literally being equal to zero? I might be misunderstanding but it would make a lot more sense if the probability is never technically zero, just close enough that mathematically it's effectively zero

  • @tobyharris4777
    @tobyharris4777 ปีที่แล้ว

    So the way I think of it is each of those values is not P(0), but the smallest positive value above 0, which is infinitely small, and therefore converges to 0. It's technically not 0, but we have no way of writing its ACTUAL value, since its value is infinitely small.

    • @fos1451
      @fos1451 ปีที่แล้ว +1

      You just discovered hyperreal, congratulations

    • @fos1451
      @fos1451 ปีที่แล้ว

      In usually real number, infinitely small doesn't and can't exist, which is why 9.9999.... equals 10, there's no infinitely small 0.000....1

  • @geoffreytrang8670
    @geoffreytrang8670 2 ปีที่แล้ว +1

    So, is the probability that an event is a possible event with zero probability still zero? If so, then not only do such events exist, but also the event that an event is such an event is itself such an event. Or for that matter, what about the probability that a possible event has zero probability, or the probability that a zero-probability event is possible? Are those two probabilities also zero?

  • @christianfrassl7107
    @christianfrassl7107 4 ปีที่แล้ว

    Great Videos! I really appreciate watching them!

  • @iiiiii-w8h
    @iiiiii-w8h ปีที่แล้ว

    Any truly random draw from a continuous probability function is a transcendental number.

  • @shieldphaser
    @shieldphaser 4 ปีที่แล้ว

    If the probability truly is zero, then barring a fault in the model it is impossible. In your case, the probability isn't zero - it's simply been rounded to zero because the actual probability is some small decimal number which is annoying to write down. Hence, probability of 0 means impossible assuming that the probability is *actually* 0.

  • @minerharry
    @minerharry 3 ปีที่แล้ว +261

    1:37 Those are some nice decimal places you have there. I recognized pi, obviously, followed by e and then later phi; but that third one was strange. 4.6692? What kind of a number was that? That’d have to be the square root of like 19, which is a weird number. Curious, I looked it up, and - with no context - the Wikipedia page for the Feigenbaum constants came up. Wikipedia pages on higher math are completely unreadable, of course, so I looked it up on TH-cam and found a Numberphile video on it, because Numberphile has a video on every single number, and - because of a tiny little Easter egg in a video that I was rewatching for the second time - accidentally learned about a completely unrelated branch of mathematics and an incredibly strange phenomenon that arose therein.
    I love the internet, and I love your videos

    • @davids.4431
      @davids.4431 ปีที่แล้ว +8

      I love MItchell Feigenbaum. I think you'll like the book "Chaos" by James Gleick that covers the story of Chaos Theory (and related stuff, like non-linearity) very well. I have to say though, it's meant for the layman, so it does not go in-depth on any of the topics. It's more of a 'review' of the scientific community at the time, and the challenges of the emerging change brought by the idea of Chaos Theory (and those who thought about those ideas).

    • @luigiboy72
      @luigiboy72 ปีที่แล้ว +1

      @@davids.4431 wait there's literally a theory called Chaos Theory??

    • @davids.4431
      @davids.4431 ปีที่แล้ว +1

      @@luigiboy72 though the name is a bit misleading nowadays, it started off as the study of disordered and seemingly random behavior (be it of the weather or of certain equations), so they deemed it appropriate to call it chaos back then. Suffice to say that the badassery of studying 'chaos theory' was very welcomed by scientists in 1970, especially after a decade of fighting for it to be 'officially' recognized. Anyway, I highly recommend the book I mentioned if it has piqued your interest!

    • @jb888888888
      @jb888888888 ปีที่แล้ว +3

      It's literally impossible for Numberphile to have a video on every single number.

    • @Mayank-tm2km
      @Mayank-tm2km 4 หลายเดือนก่อน +1

      @@jb888888888we need a video on probably of numberfile not having a video on every number xD

  • @adrift8871
    @adrift8871 4 ปีที่แล้ว +2688

    I like how whenever he says something, the little student pi's go like: *hmmmmm*

    • @lukarikid9001
      @lukarikid9001 4 ปีที่แล้ว +59

      xPureOblivion "It's big brain time"

    • @bowel_movement
      @bowel_movement 4 ปีที่แล้ว +22

      @@fatihaksu1830 ?

    • @anthonyontv
      @anthonyontv 4 ปีที่แล้ว +4

      xPureOblivion that is also what I took from this

    • @Safwan.Hossain
      @Safwan.Hossain 4 ปีที่แล้ว +7

      @@fatihaksu1830 u

    • @genhen
      @genhen 4 ปีที่แล้ว +13

      we are the little πs

  • @BenedictGS
    @BenedictGS 3 ปีที่แล้ว +806

    9 month later still waiting for part 3, it is okay take your time.

    • @Complexitivity
      @Complexitivity 3 ปีที่แล้ว +10

      ME TOOO!!!!

    • @warchiefoomii
      @warchiefoomii 3 ปีที่แล้ว +2

      @@Complexitivity +10. i'm in raptures as to how this all ends

    • @a.fleischbender7681
      @a.fleischbender7681 3 ปีที่แล้ว +29

      One year and 5 days now. Still waiting.

    • @Complexitivity
      @Complexitivity 3 ปีที่แล้ว +7

      @@a.fleischbender7681 god damn it how do we get his attention, i wanna watch all 3 in order again

    • @Rubbenzito
      @Rubbenzito 3 ปีที่แล้ว +24

      In Latin it is called "coitus interruptus"

  • @jacemandt
    @jacemandt 4 ปีที่แล้ว +3476

    One of my favorite math jokes, relevant here:
    A mathematician is a little drunk, and nudges the guy next to him at the bar and says, "Hey, think of a number. Any number at all." The guy says, "*Any* number?" "Yeah, any number."
    "Okay, I got one," the guy says. "Is it rational?" the mathematician asks?
    "Ummmm...yes..."
    "HOW UNLIKELY!!!"

    • @jasmeetk0
      @jasmeetk0 4 ปีที่แล้ว +104

      That's a good one

    • @justsomeguywithhalfamustac6837
      @justsomeguywithhalfamustac6837 4 ปีที่แล้ว +227

      I'm big dumbness and I no get

    • @henriquerock703
      @henriquerock703 4 ปีที่แล้ว +81

      @@justsomeguywithhalfamustac6837 i feel you dude,didnt get it either

    • @justsomeguywithhalfamustac6837
      @justsomeguywithhalfamustac6837 4 ปีที่แล้ว +16

      @@henriquerock703 yes

    • @SgtSupaman
      @SgtSupaman 4 ปีที่แล้ว +823

      @@justsomeguywithhalfamustac6837 , there are infinite numbers. In the infinite set of numbers, an overwhelming majority are irrational, so much so that, if something were to pick any number at random from the infinite set of all numbers, the probability of picking a rational number is 0.
      A good way to illustrate that the probability of picking a rational number is 0 is to just imagine that you are creating the number you pick one digit at a time with each of the possibilities (0-9) being equally likely. So, to get a rational number, when you are picking the digits that go after the decimal point, you would basically have to get an infinite amount of zeroes in a row.

  • @Mindraker1
    @Mindraker1 4 ปีที่แล้ว +226

    "Boy, this looks like Integral Calculus..."
    ...
    "Oh"

  • @nanigopalsaha2408
    @nanigopalsaha2408 4 ปีที่แล้ว +1505

    1:31 If the numbers after 7 seem familiar, they are:
    0
    1
    π
    e
    The Feigenbaum Constant
    φ

    • @giannisr.7733
      @giannisr.7733 4 ปีที่แล้ว +117

      After I saw π and e knew the other 2 were not random, thank you friend

    • @malignusvonbottershnike563
      @malignusvonbottershnike563 4 ปีที่แล้ว +409

      Well, considering the date of upload, it's nice to find a couple of Easter eggs in this video :)

    • @dexter2392
      @dexter2392 4 ปีที่แล้ว +50

      Good to see the Feigenbaum Constant is now considered somewhat of a famous number among math fans along with pi, e and the golden ratio. Veritasium might have something to do with it...))

    • @hongkongball7101
      @hongkongball7101 4 ปีที่แล้ว +18

      @@dexter2392 I like to think of it as a tribute to Mitchell Feigenbaum who sadly died last year in June

    • @sadhlife
      @sadhlife 4 ปีที่แล้ว +12

      it's sad how fiegenbaum doesn't have a universally known symbol yet

  • @saurabhmehta7681
    @saurabhmehta7681 ปีที่แล้ว +519

    This series really makes probability and its probabilities click for me. Hopefully the long awaited part 3 will be uploaded soon :)

    • @Daniel-cc6gs
      @Daniel-cc6gs ปีที่แล้ว +66

      @@mEhLord19 brother it's 2$

    • @stuiedaman
      @stuiedaman ปีที่แล้ว +93

      ​@@Daniel-cc6gs rich

    • @orvinal2883
      @orvinal2883 ปีที่แล้ว +43

      ​@@Daniel-cc6gs in my country 2 dollars will feed my family for a day. That a lot of money and take several days of work to get.

    • @Daniel-cc6gs
      @Daniel-cc6gs ปีที่แล้ว +8

      @@orvinal2883 where are you from?

    • @orvinal2883
      @orvinal2883 ปีที่แล้ว +67

      @@Daniel-cc6gs Milwaukee

  • @grivar
    @grivar 4 ปีที่แล้ว +343

    Interesting approach. So far, when I've seen PDFs in the wild, I've interpreted them with a PDF viewer. No longer!

    • @OrangeC7
      @OrangeC7 4 ปีที่แล้ว +20

      I knew I was doing it wrong the entire time!

    • @muchozolf
      @muchozolf 4 ปีที่แล้ว +5

      Asking the important questions right here

    • @ZackXa
      @ZackXa 4 ปีที่แล้ว +6

      Adobe Reader works pretty good.

    • @fygarOnTheRun
      @fygarOnTheRun 4 ปีที่แล้ว +5

      You should not have seen any of them in the wild in the first place. Printing out PDFs is just so 90s ...

    • @professoreggplant9985
      @professoreggplant9985 4 ปีที่แล้ว +1

      Silly little distractions every time I had to write PDF on my work.. Cursed ambiguities