Following the drops dancing on a water surface, I was sent a link to drops jumping around on a super-hydrophobic surface:

A sphere is the minimum energy configuration, and this energy scales with surface/volume ratio; small spheres combining will represent a change in energy, and this energy shows up as a vibrational mode of the droplet, so it can launch itself off of the hydrophobic material. Bigger drops don’t display the behavior because the energy released is smaller in proportion to the mass that’s present.

Like so many things in science, it is probably obvious in hindsight that it has to be this way, but the real trick is thinking of looking for it ahead of time.

In an earlier post we saw other drop dynamics in microgravity that shows the vibrations when drops combine.

h/t to Tea With Buzz