Mats Vermeeren
Mats Vermeeren
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Iterations part 2: period three implies chaos
In this second part, we try to understand why chaos occurs. We outline an argument that the existence of a 3-periodic solutions implies that the system in question is chaotic.
The argument is adapted from the paper mentioned in the video:
Li, Tien-Yien, and James A. Yorke. "Period three implies chaos." The theory of chaotic attractors (2004): 77-84. link.springer.com/chapter/10.1007/978-0-387-21830-4_6
More on the Sharkovsky ordering can be found here:
www.scholarpedia.org/article/Sharkovsky_ordering
Two good books on nonlinear and chaotic dynamics are
"Chaos" by James Gleick - a popular science book covering the history of chaos theory as a mathematical discipline
"Nonlinear dynamics and Chaos" by Steven Strogatz - an undergraduate textbook
This is part 2 of a 2-part series. The first part was my entry for the 2024 Summer of Math Exposition #somepi
These animations are made using Manim. The source code can be found at github.com/mvermeeren/SoMEpi (beware: it is rather poorly written)
This video is supported by LoughboroughUniversity and the EPSRC who graciously allow me to spend part of my time on outreach activities, #scicomm and #mathscomm. The content of this video and any mistakes it may contain are my own responsibility.
The background music is an excerpt of Oxalis by Alex Bainter (CC BY 4.0) via generative.fm
zhlédnutí: 246

Video

Iterations part 1: modelling a population of butterflies
zhlédnutí 344Před 21 dnem
Iteration means repeated application of a function. Iterating a function known as the "logistic map" gives a simple model to simulate population dynamics. In this video we introduce some key concepts and lay the groundwork for part 2, in which we take a deeper dive into one aspect of chaotic dynamics. A few videos discussing the bifurcation diagram shown at the end: Veritasium: czcams.com/video...
The shapes of waves of ships and ducks
zhlédnutí 36KPřed 2 lety
The wake of a duck, a ship, or anything in between, all have the same shape. To explain why, we need to discover a few things about the mathematics of water waves. This video is submitted to the 2022 Summer of Math Exposition #SoME2 The description of ship waves is a common topic in textbooks on hydrodynamics, for example [James Lighthill. Waves in Fluids. Cambridge University Press, 1978] The ...
Rainbows don't work the way you think they work
zhlédnutí 155KPřed 3 lety
A visual explanation of the mathematics at the end of the rainbow. I learned this explanation from V.I. Arnold's book "Mathematical Understanding of Nature", where you can also find the calculations hidden behind these animations and graphs. bookstore.ams.org/mbk-85/ The rainbow photo is by Kodyak Tisch on flickr. flickr.com/photos/91281949@N05/8317396744 #SoME1

Komentáře

  • @clavnico
    @clavnico Před 7 dny

    Thanks for the video! I have not read the paper yet (dont search libgen to avoid the paywall by the way) but one thing i feel is missing is the explanation on why the solutions do not stay close together which i think is an important property of chaos.

  • @ktbbb5
    @ktbbb5 Před 18 dny

    What about when r=1+√8 (= 3.8284..)? According to the bifurcation diagram there is a stable 3-periodic cycle without chaos around that value.

    • @MatsVermeeren
      @MatsVermeeren Před 17 dny

      Ah, you have spotted the reason why this definition of chaos isn't very good! There are still periodic orbits with any period with that value of r, but they are all unstable, except the 3-periodic one. So if we start with a random initial condition it will almost surely converge to the 3-periodic one.

  • @TheGamingHungary
    @TheGamingHungary Před 18 dny

    Nice video! One thing I'd like to note is that I was kinda lost a bit starting at 4:06 when both axis had the same intervals a-b-c, implying the interval is the same on x and F(x). Am I just dumb to imply this or is this a possible oversight? If the latter, I think just having capital A-B-C on either axis could be a little helpful to make sure the viewer does not imply the interval lengths being equal.

    • @MatsVermeeren
      @MatsVermeeren Před 17 dny

      Thanks! They are the same a, b, and c (they are the values of the 3-periodic solution). The intervals [a,b] and [b,c] remain the same. The subintervals that change in every step are not marked on the axes.

  • @MCGeorgeMallory
    @MCGeorgeMallory Před 19 dny

    Thank you for the amazing video!

  • @jakeaustria5445
    @jakeaustria5445 Před 20 dny

    Thank You

  • @Overtheglobalhorizon119

    I have been waiting for a long time and i am happy that you have just restarted😃

  • @bernhardwerner361
    @bernhardwerner361 Před 22 dny

    Ha! I also made a video on population dynamics for SoMEπ! Was a really nice explanation!

  • @ferdimro2755
    @ferdimro2755 Před 2 měsíci

    my feeling. right now.

  • @demidron.
    @demidron. Před 4 měsíci

    Yes, the brightness of the area inside the rainbow is often dramatic compared to the darkness around it. This was a very good explanation for why that is.

  • @JohnnyTokens1
    @JohnnyTokens1 Před 5 měsíci

    So then why does a double rainbow have reversed colors comparatively to the original rainbow. This wouldnt explain this if this were true both rainbows color pattern would be the same. It almost like the truth is they're reflecting of a glass dome like structure above us...hmmmm

    • @jeffjo8732
      @jeffjo8732 Před 3 měsíci

      Short answer: it's upside down, not reversed. In the primary, light that hits the drop dead center reflects at ɑ=0°. As the initial angle of incidence increases, all colors are reflected up to about ɑ=40°. Then, in VIBGYOR order, each reaches a maximum of brightness and then drops out completely. Thus red is on the outside of the primary rainbow. In the secondary, because there are two internal reflections, light that hits the drop dead center reflects at ɑ=180°. That is, in the same direction of the original ray of sunlight. As the initial angle of incidence increases, all colors are reflected *_down_* to about ɑ=54°. So, the white part of the secondary extends from the sun, past the zenith (straight up), to about 10° above the primary. Then, again in VIBGYOR order, each reaches a maximum of brightness and then drops out completely. But this is happening as your eye moves down, not up as in the primary. Red is on the "outside" of the secondary rainbow, meaning furthest from the effect's center (the sun), but you see it upside down.

  • @staxtry
    @staxtry Před 8 měsíci

    Great explanation. Thanks.

  • @HolyG-sus
    @HolyG-sus Před 10 měsíci

    Wow wtf

  • @valeriobertoncello1809
    @valeriobertoncello1809 Před 11 měsíci

    Nice video, but I think the way you explained it is a little misleading in the end. The way you said it makes it seem like the actual rainbow that we see in the sky is made of the light reflected by the droplets at the center of it. But actually, every droplet in the sky creates the circular iris that you showed, and the final rainbow is a composition of light coming from these millions of irises.

  • @xSkitZx
    @xSkitZx Před rokem

    This only half explains it though. There isn't one water droplet hanging in mid air. So how is it formed when there are millions of raindrops constantly moving? Ontop of that, why do rainbows only tend to appear after the rain has stopped?

  • @Bergja
    @Bergja Před rokem

    This is the windiest video ive ever watched

  • @EarlJohn61
    @EarlJohn61 Před rokem

    I have, once, seen 3 independent rainbows in the sky at the same time... I was 12 years old and it was about 3 days after the local area had recorded about 1½ times its average annual rainfall in 36 hours, filling 2 normally dry lakes nearby... The morning was extremely still, the smoke from the neighbour's farmhouse (4 miles to the north) was going straight up. I was heading to school and was at a point about ½ way between the two lakes, the sun rising over the hills behind me ... The largest and clearest of the rainbows was directly west of me... The other two were _about_ 22° to the north & south of that line and both looked "dirty" as if there was some mud mixed in with the rainbow... It took me a while to realise that the surfaces of the two lakes were probably the light sources for these and *they* were very muddy bodies of water which explained the colour mix.

  • @user-kv2es2pe5h
    @user-kv2es2pe5h Před rokem

    演算法帶我來了,解說很清楚

  • @dijkb
    @dijkb Před rokem

    Please tell me how you know what I think.

  • @bixenteartola6777
    @bixenteartola6777 Před rokem

    This reminds me of the legendary lecture on rainbows by Walter Lewin (highly recommend it too as a complement of this one! czcams.com/video/iKUSWJWMSk4/video.html ). But your video goes directly to the point and is really well made, good job!

  • @shantanuaphale3966
    @shantanuaphale3966 Před rokem

    Excellent explanation ❤

  • @Bamdeidz
    @Bamdeidz Před rokem

    woaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhh

  • @peakmati
    @peakmati Před rokem

    There is actualy always two rainbows . One is brighter, the other is less visible

  • @jonathanlister5644
    @jonathanlister5644 Před rokem

    Very nice but why no reference to Lord Kelvin at the university of Glasgow who solved this blooming years ago? He also built a mechanical machine to work out tides anywhere on the planet.

  • @SojournerDidimus
    @SojournerDidimus Před rokem

    Ga je nog een tweede video over dubbele regenbogen maken?

  • @TheNameOfJesus
    @TheNameOfJesus Před rokem

    For a fairly similar reason Starlink Satellites are easier to access around 53 degrees north latitude. (I.e., easier to access in Canada than in the USA!)

  • @mikosoft
    @mikosoft Před rokem

    I knew about the brighter inside and also correctly understood that is because of how the rays reflect. But this is a much more compete explanation.

  • @Copleyfundresearch
    @Copleyfundresearch Před rokem

    Wonderful

  • @hudumannaia
    @hudumannaia Před rokem

    Color of rainbow is finite (isnt infinite).

  • @maheshkanojiya4858
    @maheshkanojiya4858 Před rokem

    Incredible video

  • @michaelsearing8369
    @michaelsearing8369 Před rokem

    Another effect is that more light hits near the edge of droplets than at the center. This is because there's more area at a larger radius (the area integral formulation of a circle being r*dr*dθ). Your visual integration of the alpha-vs-d graph seems to be missing this effect. Taking it into account would give more weight to light reflected at a higher d, making the rainbow itself appear even brighter than the interior region. You could show this by plotting alpha vs d^2 then doing the visual integral on that.

  • @szabobarna5393
    @szabobarna5393 Před rokem

    Intresting, and how would you explaine duble rainbows?

  • @jakethomas6123
    @jakethomas6123 Před rokem

    I wondered why the inside is brighter. Great 360 example: czcams.com/users/shortscwQbEo75k70?feature=shared

  • @andykay479
    @andykay479 Před rokem

    I've never before a good explanation of why the inside of a rainbow is brighter than the outside. Thanks!

  • @therhythm42
    @therhythm42 Před rokem

    Excellent video and explanation!

  • @childofthe60s100
    @childofthe60s100 Před rokem

    How do YOU know what people think?????????

  • @rkalle66
    @rkalle66 Před rokem

    This video shows the second level of explanation. The next level would take into account the degree of internal reflection within a raindrop and polarizing light.

  • @Russianmafia10
    @Russianmafia10 Před rokem

    And a double rainbow is light that comes in and has one more reflection in the droplet

  • @Russianmafia10
    @Russianmafia10 Před rokem

    This works exactly how i thought they worked. We did the refraction calculations in calculus and it was really interesting to learn

  • @Laserblade
    @Laserblade Před rokem

    Thank you, rainbows are neat! The arc of the rainbow describes the base of a light cone whos apex is your eye. A person standing next to you sees a different rainbow.

  • @randyhouse5380
    @randyhouse5380 Před rokem

    life, the universe, and everything

  • @maxgedo
    @maxgedo Před rokem

    Челхарош

  • @LOGICALMAGNET
    @LOGICALMAGNET Před rokem

    Ok what about double Rainbows one small and one larger? I have the proof

  • @bgiv2010
    @bgiv2010 Před rokem

    But what about the color reversal for double and triple rainbows?

  • @hans-uelijohner8943

    A rainbow viewed from above e.g. in an airplane or on a mountain you can see the bright center of the rainbow created by direct reflection in the droplets. In the very middle you can see the shadow of the airplane or your mountain.

  • @Pocketfarmer1
    @Pocketfarmer1 Před rokem

    I didn’t know rainbows worked. I thought they mostly are unemployed.

  • @cavesalamander6308
    @cavesalamander6308 Před rokem

    You should have considered the graph of the energy of the light returned to the observer, taking into account the division of light at the boundaries of the media (including the effect of total internal reflection from the rear surface of the drop).

  • @pernormann4869
    @pernormann4869 Před rokem

    Rainbows dont work at all, they're sunbathing. 🤓

  • @gibbogle
    @gibbogle Před rokem

    You mean there's no pot of gold?? Bugger!

  • @samuelgusfield2536
    @samuelgusfield2536 Před rokem

    I guess Mats Verneeren found the rainbow connection, I hope Kermit isn’t disappointed