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Exponential growth and epidemics

2020-03-08

[public] 5.77M views, 168K likes, 1.83K dislikes audio only

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A primer on exponential and logistic growth

Help fund future projects: https://www.patreon.com/3blue1brown

An equally valuable form of support is to simply share some of the videos.

Special thanks to these supporters: http://3b1b.co/covid-thanks

Home page: https://www.3blue1brown.com

Excellent visualization of this kind of growth from Minutephysics and Aatish Bhatia:

/youtube/video/54XLXg4fYsc

Data source: https://www.worldometers.info/coronavirus/coronavirus-cases/#case-tot-outchina

Some have (quite rightfully) commented on how you shouldn't look at the R^2 of linear regressions on cumulative data since even if the changes from one day to the next are completely random, the totals they add up to wouldn't be independent of each other. Since the derivative of an exponential should also be an exponential, we could instead run the same test on the logarithms of the differences from day to day, which in this case gives R^2 = 0.91.

While this video uses COVID-19 as a motivating example, the main goal is simply a math lesson on exponentials and logistic curves. If you're looking for a video more focused on COVID-19 itself, I'd recommend taking a look at this one from Osmosis: https://youtu.be/cFB_C2ieW5I

Extrapolation xkcd: https://xkcd.com/605/

Thanks to these viewers for their contributions to translations

Hebrew: Omer Tuchfeld

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These animations are largely made using manim, a scrappy open source python library: https://github.com/3b1b/manim

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.

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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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How To Tell If We're Beating COVID-19 by minutephysics
/youtube/video/54XLXg4fYsc
Intro
/youtube/video/Kas0tIxDvrg?t=0
Viruses
/youtube/video/Kas0tIxDvrg?t=60
logarithmic scale
/youtube/video/Kas0tIxDvrg?t=112
Logistic Curve
/youtube/video/Kas0tIxDvrg?t=287
Growth Factor
/youtube/video/Kas0tIxDvrg?t=341
Fractal Pattern
/youtube/video/Kas0tIxDvrg?t=408
3Blue1Brown 3Blue1Brown, by Grant Sanderson, is some combination of math and entertainment, depending on your disposition. The goal is for explanations to be driven by animations and for difficult problems to be made simple with changes in perspective. For more information, other projects, FAQs, and inquiries see the website: https://www.3blue1brown.com
/youtube/channel/UCYO_jab_esuFRV4b17AJtAw
Simulating an epidemic 5,061,661 views
/youtube/video/gxAaO2rsdIs