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Clouds in My Coffee
Written November 10, 2004

Have you ever looked closely at the cream in a cup of coffee?

If you don't keep the liquid well stirred, the lighter cream may separate from the darker beverage.

Mysterious patterns emerge.

When we were freshman physics majors at Oberlin College, my friend Jan Olson became curious about the phenomenon.

Like any good scientist, she decided to collect some experimental data.

Having no access to photographs like these, she went home for Christmas vacation.  She prepared several cups of coffee, let them sit, and then sketched the patterns that developed.  Later she showed me her notebook, and I copied this page.


But what was really going on?  There were no theories, no conclusions.

A quarter century later, in early December of 1990, I ran across a short article in a science magazine that discussed this very question.  (To read the article, click here.)

The quoted researcher was not Jan Olson but rather geophysicist Peter Olson (no relation).  He drew parallels between coffee cup convection and movement in the interior of the Earth.

Although the article lacked illustrations of any kind, the coincidence was sufficiently striking to inspire me to forward the magazine to my college classmate.  I also enclosed the following note, in which I endeavored to achieve rhymingness.

You Olsons, for three hundred months, have professed
Fascination with patterns you find in your coffee.
You claim that you document clouds and the rest
With your sketches and words — but without photogroffy!

I never use cream.  I'm a tea drinker, so
In my kitchen there's no coffeemaker electrical.
Lacking the proof that a photo would show,
With no first-hand experience, I remain skeptrical.

Gaze then at all of your mugs, cups, and glasses!
From swirlings deduce what goes on in Earth's mantle!
For my part, I'll watch the convection of gases
And light up the room with a bright Christmas cantle.



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