Universe in a Puddle: Waves, Clouds, Trees, Oil Sheen and Bugs

August 07, 2019

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Photographer: John Adam
Summary Author: John Adam

There is a lot going on in this picture. Hiking down from the summit of Mount Gorham about a week ago I noticed this puddle on a rock with a biofilm sheen on the surface. I presume some disturbance of the water had broken up the biofilm; in all probability, it was by vibrations from people pounding the rock next to it as they climbed up and down or someone walking in the puddle itself! The reflection of the clouds, sky and nearby trees can be seen clearly as well.

What I found most fascinating was the vibrations of the water caused by a struggling bug or fly generating capillary waves, which (for me) adds to the beauty of the picture. In fact, there’s a more visible larger bug towards the bottom of the picture, though its wave pattern is less obvious; nevertheless, some circular arcs can be seen in the middle of the picture intersecting the first group. Notice the region of calm in the center of the set of concentric circles. This shows that the waves are indeed dominated by forces associated with surface tension (as opposed to gravity) because of the consequence of their short wavelengths (of the order of several mm, certainly less than 1 cm).