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Top: An electron microscope photo of long, straight waveguides (left) interrupted by an accidental scratch during fabrication, that turned the orderly stripes into naturalistic chaos. Each structure is about 0.5 microns high, or less than 1/200 the thickness of a typical human hair.

Bottom: A photo on quite a different size scale, taken by astronaut Terry W. Virts (@AstroTerry) from the International Space Station. https://twitter.com/AstroTerry/status/590989419378712576 The hills in both photos were likely formed by similar mechanisms, on very different timescales - the nanofabrication was done in a plasma etcher, and etching took a matter of minutes.  The macroscale hills were etched by wind and water, and the process took millennia.