A crazy approach to the gaussian integral using Feynman's technique

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  • Опубликовано: 17 янв 2025

Комментарии • 89

  • @Decrupt
    @Decrupt Год назад +196

    NOT THE REVERSE COWGIRL FOR INTEGRALS NOOOOO

    • @maths_505
      @maths_505  Год назад +27

      😂😂😂

    • @stapler942
      @stapler942 Год назад +47

      This is the first time in my life I have ever heard the phrase "reverse cowgirl" applied to mathematics and it's got me giggling. 😂
      Physics: "for simplicity in this example we will assume a spherical reverse cowgirl in a frictionless vacuum..."

    • @RichardJohnson_dydx
      @RichardJohnson_dydx Год назад +4

      Unexpected but welcomed.

    • @TheArtOfBeingANerd
      @TheArtOfBeingANerd Год назад +4

      No because I told my mom I would keep my youtube PG while watching my brothers and she literally walked in when it said reverse cowgirl

    • @jmcsquared18
      @jmcsquared18 7 месяцев назад

      ""Physics is like sex. Sure, it may give practical results. But that's not why we do it."
      - Dick Feynman, who probably enjoyed cowgirl

  • @zahari20
    @zahari20 Год назад +83

    In my opinion, the smoothest evaluation of the Gauss integral is to take its aquare, write it as a double integral, and use polar coordinates.

    • @TechToppers
      @TechToppers Год назад +6

      Yeah I saw some paper and they said... This is an elementary approach so much more tricky to find. More advanced techniques make it way more trivial.

  • @madhurpopli1790
    @madhurpopli1790 5 месяцев назад +3

    thanks a tonnn !!! i can finally understand this integral because the feynmann technique is fantastic. i can literally understand the gaussian integral at 17 !! THANKS A TONNN

  • @nharshithreddy8445
    @nharshithreddy8445 3 дня назад +1

    Succesfully understood the whole concept...

  • @christophermorris486
    @christophermorris486 Год назад +28

    😂😂😂 I was hooked at reverse cowgirl trick for integration

    • @maths_505
      @maths_505  Год назад +12

      If only youtube would allow me to use the corresponding thumbnail

    • @daddy_myers
      @daddy_myers Год назад +3

      @@maths_505 Technically you could, you'd just have to use a different platform.

    • @maths_505
      @maths_505  Год назад +16

      Ah yes....maths 505 on the hub😂

    • @christophermorris486
      @christophermorris486 Год назад +1

      I did watch the video with on hand….the other hand was had a pencil in it following along

    • @maths_505
      @maths_505  Год назад +7

      Had us in the first half not gonna lie

  • @zdzichumis
    @zdzichumis Год назад +9

    What a truly beautiful way to evaluate the Gaussian integral! Your work shall not be underappreciated.

  • @_nemo171
    @_nemo171 Год назад +7

    No fancy uses of Gamma function properties, a clean approach. Nice!

  • @BalajiKomanabelli-nd1xq
    @BalajiKomanabelli-nd1xq Год назад +10

    At some point it looked like Laplace's approach but it is actually a great approach.
    But the easiest way is squaring and using polar coordinates

  • @zunaidparker
    @zunaidparker Год назад +5

    Another awesome integral! Can't stop watching these!

  • @jmcsquared18
    @jmcsquared18 7 месяцев назад +2

    "A crazy approach" That alone tells you that it's gonna work.

  • @circuitcraft2399
    @circuitcraft2399 Год назад +6

    Doesn't 2:00 follow from the fundamental theorem of calculus, no differentiation under the integral required?

    • @maths_505
      @maths_505  Год назад +4

      Indeed it does but the Leibniz rule provides a nice insight into its mechanism

    • @Singularitarian
      @Singularitarian Год назад +1

      You’re right, we should just use the fundamental theorem of calculus at that step.

  • @terrariariley1643
    @terrariariley1643 7 месяцев назад +1

    I watched the video and started crying after 40 seconds

  • @doroffixial
    @doroffixial Год назад +2

    I couldnt even do simple equations in math yet i‘m here watching this and literally understanding zero. This stuff gives me ptsd from highschool times.

  • @yoihenbalaishram8903
    @yoihenbalaishram8903 Год назад +2

    That was very, very clever. Especially the substitution part....

  • @cot2a
    @cot2a Год назад +3

    Another way is, simply do substitution x^2 = t, then use Feynmann technique within this use the Gamma function and then the Laplace transformation porperty, L [f(t)/t] = int{s to inf} L(S) ds.

  • @pacotaco1246
    @pacotaco1246 Год назад +1

    This is a really cool way to do it besides switching to polar. Nice!

  • @trelosyiaellinika
    @trelosyiaellinika 2 месяца назад

    Cool! Really cool! I do not know how many ways to solve the Gaussian integral I have seen so far, including contour integration, and I am still fascinated and excited by yet another approach... Yes, maybe squaring and using polar coordinates is the easiest and most popular way but using various other approaches is a good massage for the brain... Besides, it keeps your vigilance to be able to see similar possibilities in solving other integrals.

  • @cadmio9413
    @cadmio9413 7 месяцев назад

    Thanks, this is one of my favourite videos on all the platform, never really understood polar cordinates :p

  • @cameronspalding9792
    @cameronspalding9792 Год назад +2

    I would define the square of the integral to be J(t) not I(t), namely because I is defined as being the integral from zero to infinity.

  • @chengfang545
    @chengfang545 8 месяцев назад

    I didn't quite understand the change of variable in 3:31 can someone explain? thank u

  • @Chris_387
    @Chris_387 Год назад +1

    When taking the derivative why you do these with the limits? Is there a general rule?

    • @maths_505
      @maths_505  Год назад

      The Leibniz rule

    • @Chris_387
      @Chris_387 Год назад

      @@maths_505 okay and why d(0)=0?, how do you evaluate if you have a number

  • @aayushiajith.
    @aayushiajith. Год назад +2

    Can anyone suggest me a book to start with feynmanns integrals???

    • @robertbachman9521
      @robertbachman9521 Год назад +3

      Paul Nahin's 'Inside Interesting Integrals' is an entertaining book. He has a Chapter on Feynman's technique and another on contour integration. That is only 2 of the 9 chapters. There are some mind blowing problems in there about realistic problems from math and physics.

    • @indescribablecardinal6571
      @indescribablecardinal6571 Год назад

      ​@@robertbachman9521Thank you very much, this will be so helpful for physics.

  • @andikusnadi1979
    @andikusnadi1979 Год назад

    at 0:54 why its square ? thank you sir.

    • @maths_505
      @maths_505  Год назад

      Watch the rest of the video
      It'll become clear

  • @harley6659
    @harley6659 24 дня назад

    Which app are you using to annotate

  • @mohamednour7680
    @mohamednour7680 Год назад

    We can use the gamma function and it will be in the end gamm(1/2)= √π

  • @AndDiracisHisProphet
    @AndDiracisHisProphet Год назад +1

    excellent thumbnail choice

  • @NightWanderer31415
    @NightWanderer31415 Год назад +4

    Very nice! Nitpicking, you could have explained why the limit can be taken inside the integral in the final step.

    • @maths_505
      @maths_505  Год назад +9

      Ah yes the interchange of limits....you're right....although the integral's convergence is trivial given its form it would've been better to mention this to justify taking the limit inside the integral operator

  • @aryaghahremani9304
    @aryaghahremani9304 Год назад

    bro just pulled a reverse feynman technique, never seen a partial derivative be taken out of the integral
    wtf did I just watch lmao

    • @maths_505
      @maths_505  Год назад

      The reverse cowgirl formulation of calculus

  • @yudoball
    @yudoball Год назад +1

    That's a cool trick

  • @pseudonimo224
    @pseudonimo224 3 месяца назад

    Awesome!!!!

  • @worldnotworld
    @worldnotworld 2 месяца назад

    I'm lost after 2:14...

  • @Fr_Epic
    @Fr_Epic Год назад

    What application is he using to solve this integral?

  • @michaelbaum6796
    @michaelbaum6796 Год назад

    Thanks a lot for this cool solution👌

  • @randomeme3484
    @randomeme3484 Год назад +1

    Well gamma function is op

  • @rythmx123
    @rythmx123 Год назад

    how did u come up with the I(t) and then square it lol

    • @maths_505
      @maths_505  Год назад

      I evaluated the fresnel integrals the same way so I applied it here. I got the fresnel integral approach from flammy but he messed up near the end with the complex exponential so I just improved on it.

    • @rythmx123
      @rythmx123 Год назад

      @@maths_505 you're amazing man! no words only respect :)

    • @rythmx123
      @rythmx123 Год назад

      @@maths_505 i'll be honest here, im just watching these vids for fun cuz my love's not with me and im kinda lonely and missing her haha... math's just awesome! i haven't studied calculus in that depth but watching you makes me realise there's so much i need to learn, thanks ❤️

  • @justasmilingemotionlessguy5903
    @justasmilingemotionlessguy5903 Месяц назад

    REVERSE WHAT?

  • @chrissch.9254
    @chrissch.9254 Год назад

    Lovely!

  • @mars_titan
    @mars_titan Год назад

    How can I suggest you a problem? Mail?

    • @maths_505
      @maths_505  Год назад

      It's in the about section of the page

  • @rido4822
    @rido4822 Год назад +1

    U r Monster

  • @manstuckinabox3679
    @manstuckinabox3679 Год назад +1

    ahh... a classic problem solved in a classic way, you should try with contour integration next.
    0:47 THIS IS NOT CLASSIC! THIS NOT CLASSIC AT ALL!

    • @maths_505
      @maths_505  Год назад +1

      What else do you expect from the reverse cowgirl formulation of the gaussian integral 😂

    • @maths_505
      @maths_505  Год назад

      You should check out qncubed3's video on the gaussian. It's pretty cool

    • @manstuckinabox3679
      @manstuckinabox3679 Год назад

      @@maths_505 oh yeah I did, just wanted to see it from my fav youtuber, thought you might have a cool approach (his was also extrememly cool)

  • @noobiegamer9080
    @noobiegamer9080 Год назад +1

    Root pi

  • @yunwenzhu2193
    @yunwenzhu2193 Год назад

    Seems to be overkill of this problem

  • @sushil7276
    @sushil7276 Год назад

    Why I am not smart like you

    • @maths_505
      @maths_505  Год назад

      I'm not smart....just persistent...so you can do it if I can

  • @vatsalsharma4879
    @vatsalsharma4879 Год назад

    I love maths

  • @ahmeT0007
    @ahmeT0007 Год назад +1

    Ramanujan solved like this by square root he used beta function

  • @georgesmelki1
    @georgesmelki1 Год назад

    Why complicate things? It's useless! The polar coordinates method is still the best!

    • @maths_505
      @maths_505  Год назад +1

      Gamma function approach is the simplest one....if anyone complains about the Γ(1/2) thing, I would direct them to the reflection formula for the gamma function.

    • @georgesmelki1
      @georgesmelki1 Год назад +1

      @@maths_505 I agree. However, the polar coordinate approach is more elementary: we learned how to calculate the Gaussian before we evn heard about the gamma...

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    @Dodgevair Год назад

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    When the nervous contagious giggling subsides,
    how will our civilization adapt to this publicly known reality?
    What might be some of the potential implications of disclosure of this reality? New energy sources perhaps? Religions? History?
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