jeweled platypus


thursday, february 03, 2011
Observational math

I like learning geometry and topology terms that make you notice and describe patterns out in the wild:

The wires hanging between those pylons form catenary curves, which describe what happens when you hang an ideal string between two points. The word is also used for catenary wires (which power trains).

These shiny light shapes are caustics generated by a spotlight shining on a curved piece of plastic (Untitled, 1967, Giovanni Anselmo, Museum of Modern Art). You can see a typical caustic by taking a mug of tea into the sunlight and looking at the curvy, pointy light on the tea surface. This is also what you call the light patterns in the shadow of a glass and wavering at the bottom of a pool.

reaction diffusion
These wiggly lines are a reaction-diffusion system of air bubbles between two panes of glass in a layered piece of art by Dustin Yellin. This type of wiggly pattern also happens in places like bird feathers, rabbitfish scales, and shriveled paint.

Angle of repose
in the Bay Area
The dirt in this pile is showing off its angle of repose: the slope that a pile of granules forms when it is “at rest”. You can watch for the angle of repose when you shovel snow and throw it in a pile, or when you build sandcastles, depending on where you happen to live right now.

Read more

My friend Dan is writing about geometrical curiosities on his blog. My favorite post so far is an introduction to pseudospheres and tractrices.

Vi Hart makes lots of related projects including looking at the hyperbolic shriveling of dried apple slices.

Bonus words

Non-geometry-related things to find and name: bollards, wall ties, ghost signs, perforated screen walls, former Fotomats, benchmarks (find some near you), manicules, telephone exchange buildings, skeuomorphs in general. And obsolete technologies that are still in use or still visible: sidewalk prisms, Quonset huts, civil defense air sirens, glass insulators, old-style phone numbers.

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I’m Britta Gustafson.

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