Title text:
Mantle plumes explain Hawaii, Yellowstone, Iceland, the East African Rift, the Adirondack uplift, the Permian extinction, the decline of Rome, the DB Cooper hijacking, and the balrog in Moria. Those little hills of sand in your yard are caused by antle plumes.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3141/
Yeah, I guess knowledge is also a bad term. I guess a better way to say it is "when an interaction happens, so the position is concrete."