Main Page

explain xkcd: It's 'cause you're dumb.
Jump to navigation Jump to search

Welcome to the explain xkcd wiki!
We have an explanation for all 3292 xkcd comics, and only 44 (1.3%) are incomplete. Help us finish them!

 Go to this explanation

Latest comic

Size and Lifespan
With their 13 years recording and performing together and two humans worth of mass, the White Stripes are sandwiched neatly between gray wolves and blue whales.
Title text: With their 13 years recording and performing together and two humans worth of mass, the White Stripes are sandwiched neatly between gray wolves and blue whales.

Explanation

This comic presents a correlation between the size (in kg, therefore more accurately, the mass) of different objects with colors in their names, and their size and lifespan. It is similar to common charts that map the size versus lifespan of various animals, showing that, broadly, the larger they are, the longer they live, demonstrating biological allometry principles such as Kleiber's law. Here, however, it covers entirely unrelated classes of objects (animals, features of the Earth, and even astronomical bodies), appearing to suggest that there is some universal cosmic trend across all entities named with a color. Black holes are complete outliers due to their evaporation through Hawking radiation making their lifespan scale as the cube of their mass. At either end of the scale, white blood cells and stars are 'smeared' across the chart, crossing areas that fit the apparent trend, but also straying away from it.

Somewhat dubiously, the chart conflates typical lifespans in some cases with lifetime to date in others.

Items Listed
Object Size (kg) Lifespan (seconds) Approx. lifespan (human-readable) Explanation
white blood cells 10-11±0.5 104.5±1.5, and 108.25±0.75 17 minutes–12 days, and 6 years The graph separates memory lymphocytes (which need to be replaced only every few years) from the other kinds of white blood cells (which the body replaces every few days).
yellowjackets 10-4±0.5 107.25±0.5 200 days Example of a long insect lifespan
gray wolves 101.5±0.5 108.5±0.5 10 years Example of a typical mammal lifespan
blue whales 104.5±1 109±0.5 30 years Example of a long mammal lifespan
black holes ≤105.5 to ≥1011.75±1.25 ≤100 to ≥1025 ≤1 second to ≥300 quadrillion years (20 million universe lifetimes) Black holes eventually evaporate away due to Hawking radiation. 'Smaller' black holes can be surprisingly short-lived for celestial objects; however, this log-scale graph would have to be roughly four times taller to account for stellar-mass black holes (~1075 seconds, or >1057 universe lifetimes) and six times higher to account for the largest known black holes (over 10100 seconds, or >1082 universe lifetimes). Conversely, a black hole close to the Planck mass would be way off the chart to the bottom left, though these are theoretical entities potentially occurring only in extreme conditions, such as at the very beginning of the universe or in a particle accelerator; the smallest known black hole is roughly four times the mass of the Sun.
Red Sea 1017.5±0.5 1015±1 30 million years The time probably references the end of the desiccation of the Red Sea.
Greenland 1020±0.5 1016.75±0.5 2 billion years An autonomous territory of of Denmark, Greenland is the world's largest island. Greenland makes an interesting pairing with the Red Sea, because red is the opposite of green and sea is the opposite of land.
red dwarfs to blue giants 1029 to

1032.5

1021 to

1013.5

1 million years to 30 trillion years Stars are probably some of the largest and longest-lasting single things in the universe. The inverse relationship between mass and lifespan (which goes against the overall suggested relationship of the chart) is because massive stars fuse hydrogen to helium far faster. The charted region is effectively an inverse of the famous Hertzsprung–Russell diagram, with the stellar classification (surface temperature) being inversely proportional to mass, and luminosity (rate of fusion) being inversely proportional to lifespan.
The White Stripes (title text) 102 108.65 14 years The White Stripes were a rock duo from 1997-2011 made up of Jack and Meg White.

Transcript



        View comic discussion

New here?

You can read a brief introduction about this wiki at explain xkcd. Feel free to create an account and contribute to the wiki! We need explanations for xkcd comics, characters, What If? articles, and everything in between. If it is referenced in an xkcd comic, it should be here.

  • The incomplete explanations are listed here. Feel free to help out by expanding them!

Rules

Don't be a jerk!

There are a lot of comics that don't have set-in-stone explanations; feel free to put multiple interpretations in the wiki page for each comic.

If you want to talk about a specific comic, use its discussion page.

Please only submit material directly related to xkcd and, of course, only submit material that can legally be posted and freely edited. Off-topic or other inappropriate content is subject to removal or modification at admin discretion, and users who repeatedly post such content will be blocked.

If you need assistance from an admin, post a message to the Admin requests board.