913: Core

Explain xkcd: It's 'cause you're dumb.
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If you're a geologist or geophysicist and you don't introduce yourself by saying your name, then gesturing downward and saying "... and I study that", I don't know what you're doing with your life.
Title text: If you're a geologist or geophysicist and you don't introduce yourself by saying your name, then gesturing downward and saying "... and I study that", I don't know what you're doing with your life.


This comic reflects on the fact that no matter where you are on Earth, its core is always directly under you, while incredibly hot and under huge amounts of pressure. Yet most of the time, we ignore this completely unless there is a volcanic eruption (which has nothing to do with the core, but mainly with the friction between the tectonic plates).

Cueball is presumably reading a geology book with diagrams and various facts about the Earth's interior, such as the core being subdivided into an inner core and an outer core, that the inner core is a solid ball, the size of the moon, that the outer core is at a pressure of 30 million pounds per square inch (approximately 2 million times atmospheric pressure at sea level) and the outer core is made of molten metal in a constant turbulent motion - a bit like a pot of boiling water. But every time he gets 15 minutes in to such a book he freaks out, realizing this deadly stuff is right beneath him, and he bends over to look down to the Earth.

The title text makes a note of how cool it would be to study this without getting too terrified. So if you do - then let everyone you meet know what you do for a living as soon as you introduce yourself by pointing at the ground beneath you! (Despite most geologists and geophysicists not studying the core, they do study what is beneath our feet.)

Alternately, the title text may be a reference the fact that someone gesturing downward would looks like he's pointing to his genitals, which could be considered inappropriate.


[A cutaway diagram of the Earth, with colored layers including a labeled outer core and inner core.]
[A closeup of the stylized outer core, labeled "Turbulent molten metals at 30 million PSI" with turbulence lines, and of the inner core, labeled "moon-sized iron sphere."]
[Cueball reading a book pulls legs up tight under office chair, peering downwards.]
[Caption below the frame:]
I freak out about fifteen minutes into reading anything about the Earth's core when I suddenly realize it's RIGHT UNDER ME.


What people of different science fields would often think about became the subject of 2057: Internal Monologues. Geologist are not included, but the molten core beneath our feet would probably have been the choice if they had. That Randall was actually already thinking about adding geology was made clear in the next comic 2058: Rock Wall about the core/mantle beneath our feet and 20 miles of rock (wall).

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And the crust is just thin enough that volcanoes and earthquakes are a thing. Safety! Davidy²²[talk] 01:30, 17 April 2013 (UTC)

Isn't the glancing down and saying "I study that" a reference to something more inappropriate? ~ JFreund

I think that's the joke. NealCruco (talk) 17:27, 17 March 2014 (UTC)

I agree. If you stand with your arm at shoulder height and gesture downwards, saying "I study that", you will be pointing both toward the center of the earth and at your own genitals. That is the joke in the title text. (talk) (please sign your comments with ~~~~)

And if Carlos Saldanha,s documentary is correct, the earth will be filled - FILLED - with velociraptors. 15:25, 29 August 2014 (UTC)

FYI: It's not right under you. It's more like far, far, very far away from you. AND it's quite some time behind you, left of you, right of you, in front of you, and sometimes even above you. See also! (talk) (please sign your comments with ~~~~)