Skip to content
0:00 / 0:00

Exponential growth and epidemics

3Blue1Brown

8.7M subscribers • 2 videos on Rounds

YouTube
  • Recommended by 10 people, in Hacker News.

For anyone, no background needed. Education, not medical advice.

6M views6 years ago10 recommendations

Immunity and infectionEvidence and public healthInfectious diseaseEpidemiology and statisticsPublic health and policy

3Blue1Brown explains the mathematics of exponential and logistic growth in the context of infectious disease epidemics.

A primer on exponential and logistic growth Help fund future projects: patreon.com/3blue1brown An equally valuable form of support is to simply share some of the videos. Special thanks to these supporters: 3b1b.co/covid-thanks Home page: 3blue1brown.com Excellent visualization of this kind of growth from Minutephysics and Aatish Bhatia: youtube.com/watch?v=54XLXg4fYsc Data source: worldometers.info/coronavirus/coronavirus-cases/#case-tot-ou… 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: youtu.be/cFB_C2ieW5I Extrapolation xkcd: xkcd.com/605/ 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/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. Download the music on Bandcamp: vincerubinetti.bandcamp.com/album/the-music-of-3blue1brown Stream the music on Spotify: open.spotify.com/album/1dVyjwS8FBqXhRunaG5W5u 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. ------------------ 3blue1brown is a channel about animating math, in all senses of the word animate. And you know the drill with YouTube, if you want to stay posted on new videos, subscribe: 3b1b.co/subscribe Various social media stuffs: Website: 3blue1brown.com Twitter: twitter.com/3blue1brown Reddit: reddit.com/r/3blue1brown Instagram: instagram.com/3blue1brown_animations/ Patreon: patreon.com/3blue1brown Facebook: facebook.com/3blue1brown

Why it's here

10 people recommend this

What people say. Recommended as an excellent, clear explanation of exponential growth and how it applies to epidemic curves.

brownbatin Hacker News • Recommends

On “Show HN: Epidemic Simulator”

Just watched the 3brown1blue video today, which talks about exponential growth and fixes it to the latest actual COVID-19 numbers. Really helped it all click. link to this video Edit: separate HN discussion: link

officialjunkin Hacker News • Recommends

On “Show HN: HN reader that filters out COV**-19 and Coronavir** articles”

regardless of what you hear, china takes outbreaks very seriously and responds aggressively. the general population in china also takes it very seriously. normal behavior response in china looks like over reaction in the us. please watch this video by 3blue1brown link to this video china is past its inflection point and we have yet to determine where our inflection point will be. everyone should be changing your behavior now. the fact that sars-cov didn’t get as far in 2002 as sars-cov-2 virus is currently going should be concerning. the us could ignore prior outbreaks because china is aggressive to stop it.

willis936in Hacker News • Recommends

On “Covid-19 is now officially a pandemic, WHO says”

But months ago they really couldn’t have known. We still don’t know how many will be infected. All we can do is take precautionary measures. The WHO messaging should have been stronger and earlier, but it isn’t their fault for not labeling a pandemic months ago. Granted, there was enough data and research done to squarely label this as a pandemic, and that’s really where I assign blame on them. Here is a neat video that helps put things in perspective for most any viewer. link to this video

thomasmgin Hacker News • Recommends

On “Why some governments appear not to be acting on the Covid-19 threat”

To be exact, it's a "logistic curve", which initially is exponential. From this 3Blue1Brown excellent video: link to this video

arendtioin Hacker News • Recommends

On “Open letter from Italy to the international scientific community”

Maybe they should include this 3Blue1Brown video to explain what 'exponential' means in this context: link to this video

asix66in Hacker News • Recommends

On “Ask HN: What happens next after a successful lockdown?”

And those who don't understand, or need a refresher on, exponential growth should watch this great video by 3Blue1Brown. Exponential growth and epidemics: link to this video

carapacein Hacker News • Recommends

On “Shelter in place for Bay Area counties”

This is the time to resort to drastic measures to prevent drastic consequences. Have you seen this from 3Blue1Brown: link to this video "Exponential growth and epidemics" ?

ochoseisin Hacker News • Recommends

On “The Doctor Who Helped Defeat Smallpox Explains What's Coming”

3blue1brown did a good video explaining the logistic shape of pandemic curves: link to this video My key takeaway was that once you see the inflection point, you know that you’ll have roughly 2x the number infections by the time it’s done.

Fejin Hacker News • Recommends

On “‘It looks like a war zone’: NJ docs say hospitals under siege, supplies low”

…to be able to handle it and we don't have the clout of NY to push for more resources. In a recent video, 3Blue1Brown wrote "The only thing to fear is a lack of fear itself." This is what worries me. My parents are at risk as long-time smokers and if Valley runs out of ventilators and PPE, our major/usual option is out. (excellent video by the way) link to this video…

vikramkrin Hacker News • Recommends

On “Covid-19 Sanity – Covid-19 papers from bioRxiv/medRxiv searchable and sortable”

…idemiologists and leaders with decades of experience fighting pandemic after pandemic. You know, people that know what they're talking about? Might be worth trying to spend time actually learning how the people that are spending day and night trying to save your life and the lives of your loved ones do their work before dismissing them as useless. link to this video…

igraviousin Hacker News • Mentions

On “Italy is extending its coronavirus quarantine measures to the entire country”

People keep extrapolating that tens of millions will die, and I don't doubt that tens of millions surely would _if_ there were no lock-downs! (The subject of this article!) The whole point of locking down Wuhan/Hubei and then northern Italy and now the whole country and other places and cancelling large public gatherings and events is that local, regional, and national authorities start seeing the numbers soaring and initiate extreme mitigation strategies. We don't know how successful these strategies will be individually/collectively in the long run but if China is anything to go by it can severely retard the spread of the virus. To show I'm not spouting out of my derriere compare the logar…

sigstoatin Hacker News • Mentions

On “Covid-19 update and guidance to limit spread”

> That's my point: to observably flatten the curve, you need to go almost all the way there of killing it altogether. no, you don't. killing it completely would (hand-waving) require taking R0 < 1, and holding it there indefinitely. any reduction in R0 at all will flatten the curve, at least a bit. and small changes in the rate of growth can have a huge impact when you're dealing with (even temporarily) exponential growth. link to this video

ralusekin Hacker News • Mentions

On “Show HN: Tool for Visualizing Spread of Infectious Disease”

This is a simple tool for visualizing how massive the impact if minor behavioral changes can be in the spread of infectious diseases. This model is mostly based off of the math discussed in 3Blue1Brown's video on exponents and epidemics. link to this video There are tons of ways this model could be improved, so please feel free to contribute. link

csnoverin Hacker News • Mentions

On “Ask HN: Covid-19 panic – what am I missing?”

Even at a 0.7% mortality rate, you’re talking about a small percentage of a very big number. Up to 70% of the world’s population may become infected. 0 In that case, a 0.7% death rate converts into 37 MILLION deaths. The runs on toilet paper are the irrational panic of humans. I saw some comments on the internet early on in the outbreak telling people to buy anything they can’t live without for two weeks, with particular emphasis on toilet rolls, so that’s probably where that came from. With regards to the extreme measures, my understanding is that this is primarily to try to prevent health care systems collapsing. Around 20% 1 of people with COVID-19 are sick enough to need hospitalisat…

kangnkodosin Hacker News • Mentions

On “Trump Declares National Emergency”

At the current exponential rate of worldwide growth, by the end of June, we will be in one of these two scenarios: 1) Almost everyone in the world who is susceptible has it, or had it. 2) We implemented a way to slow down the global growth rate, or it slowed down by itself. One way or another, we will know in a just a few months. If you want to check the math, skip to about 3:20 on this video from 3Blue1Brown, Exponential growth and epidemics. link to this video

jiggawattsin Hacker News • Mentions

On “Open letter from Italy to the international scientific community”

All epidemiologists agree with this. All of them. They've been making public statements to that effect and signing letters reiterating the urgency of the situation. So what are you saying exactly? I don't understand what your point is! I'm agreeing with the epidemiologists. Their maths checks out. It's the same maths as my maths. It's the same maths as everyone's maths : link to this video The only people I hear disagreements from are people who don't know how to use a calculator, Or they do, but haven't bothered. Nonetheless, they seem to have lots of time argue online, dismissing logical, coherent, and factual arguments without making any defensible statements of their own.