When droplets walk across a liquid surface
When a container of silicone oil or other similar liquid is vertically shaken at a regular frequency, 1-millimeter-sized droplets of the same liquid placed on the liquid's surface appear to "walk" across the surface at speeds of about 1 cm/second, propelled by their own waves. In a new study, physicists have found that these walking droplets can be much larger (up to 2.8 mm in diameter) and faster (5 cm/second) than previously observed. These "superwalkers" exhibit a wide range of never-before-seen behaviors, including novel synchronized movements.
One of the interesting features of walkers is that, while their movements can be completely explained by classical mechanics, some of their behaviors mimic certain quantum phenomena that typically exist only at the atomic scale. Examples of such features include tunneling, quantized orbits, and correlations among multiple droplets. In a sense, droplet mechanics could be viewed as a combination of classical and quantum mechanics, where both particle and wave behaviors coexist.
Researchers Rahil Valani and Anja Slim at Monash University, and Tapio Simula at Swinburne University of Technology, have published a paper on the superwalkers in a recent issue of Physical Review Letters.
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