xkcd.WTF!?

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Ten Thousand

Saying 'what kind of an idiot doesn't know about the Yellowstone supervolcano' is so much more boring than telling someone about the Yellowstone supervolcano for the first time.

Explanation

In this strip, Randall presents a mathematical argument against the idea of making fun of people for their ignorance. The mathematical argument, presented in the first panel, goes as follows: Since people aren't born knowing anything, everyone has to learn everything for the first time at some point. By using the US national birth rate and assuming that most common facts that "every adult knows" are learned by age 30, Randall calculates that there are around 10,000 people in the US alone who learn any given common fact for the first time each day.

Since you can only learn something for the first time once, each of these 10,000 people are having a unique, unrepeatable experience of enlightenment, which Randall sees as something to be cherished, not criticized. In the second panel, Randall notes that if he makes fun of people for not knowing things, he is effectively training them to avoid sharing those moments with him, and thus he will miss innumerable opportunities to do something he considers fun. To drive the point home, the second panel shows Cueball finding out that Megan doesn't know about the "Diet Coke and Mentos thing", and - instead of making fun of her, Cueball affirms that Megan is part of a special and select group - she is one of the "Lucky 10,000" who, that day, will learn and experience that thing for the first time.

Diet Coke (sold under the names "Diet Coca-Cola" or "Coca-Cola Light" in certain countries) is a popular brand of sugar-free soda. Mentos is a brand that makes chewable mints. If they are dropped into a bottle of Diet Coke, the soda erupts with startling violence, sending a fountain of soda many meters into the air. This interaction is widely renowned due to its dramatic, unexpected nature, and the fact that you can do it with cheap and commonplace ingredients (though it does make quite a mess and should only be done outdoors). The reaction can be done with a variety of sodas (though Diet Coke is the most commonly repeated choice), and is caused by a physical reaction between the Mentos and the soda. The Mentos rapidly nucleate the carbon dioxide bubbles in the soda, causing the dissolved carbon dioxide in the soda to assume gaseous form. The sudden formation of all the carbon dioxide gas forces the contents of the bottle out. A 2006 Mythbusters episode explored the phenomenon in detail.

The Diet Coke and Mentos eruption has also been mentioned in a previous strip 346: Diet Coke+Mentos. Both the eruption and this comic were referenced much later in the what if? article Comet Ice, where the title text of the first image proclaims that "Some of the lucky 10,000 are less lucky than others", as demonstrated when Black Hat offers to "help" Cueball to stem his overflowing Diet Coke bottle by plugging the opening with Mentos. This comic also appears in a modified form in Randall's book How To, in the introduction of the book. Supervolcanos would be mentioned again in 1159: Countdown and in 1611: Baking Soda and Vinegar.

The title text states, emphatically, that explaining a fact to a person for the first time (in this case, the existence of a supervolcano within the Yellowstone National Park) is much more entertaining than just expressing annoyance about their lack of knowledge. Here is a good video about the Yellowstone supervolcano. Interestingly, both events alluded to in this comic include an eruption, although of two very different kinds.[citation needed]

Calculation

Randall does not show the full calculation in the comic, but we can derive it as follows:

  • First, assume that everyone will know a given fact by the time they reach adulthood, which is defined here to be 30 years old.
  • Assuming the US birth rate of 4 million per year, this means that in 30 years, 120 million people will be born who will learn the fact at some point.
  • 30 years is equal to 10950 days (30 years x 365 days per year). Since we have assumed that everyone will learn the fact within that time, that means on any given day, there is a 1/10950 chance that that will be the day they learn the fact.
  • So, if 120 million people have a 1/10950 chance per day of learning the fact, that means that on any given day, the number of people learning that fact will be, on average, 120,000,000 / 10,950 = 10958.9, which is approximately 10,000.

It is worth noting that the target age of 30 is actually irrelevant to the calculation. Taking the assumption of a steady birth rate, and assuming that "everyone" learns a fact at some point in their lives, then the number of births per day and the number of people learning a thing each day must average out to the same value over time. The ages at which it is learned don't affect the numbers. This calculation is obviously simplified, since birth rates are not constant over extended periods, and some people presumably die before learning certain facts, (either because they die young, or because they simply never encounter the fact). The assumptions are, however, sufficiently good to give a general estimate.

Randall's calculation is for the US, but it can be easily converted for other countries or the entire world by supplying the appropriate birth rate. For the world as a whole, the average birth rate as of late 2022 is 140 million per year, which gives a total of approximately 400,000 people learning a fact for the first time each day (140,000,000 / 365 = 383,561.6 ≈ 400,000).