Researchers see Kelvin wave on quantum 'tornado' for first time

Draining the water from a bathtub causes a spinning tornado to appear. The downward flow of water into the drain causes the water to rotate, and as the rotation speeds up, a vortex forms that obeys the laws of classical mechanics. However, if the water is replaced with extremely cold liquid helium, the fluid will swirl around an invisible line to form a vortex that obeys the laws of quantum mechanics. Sometimes, two of these quantum tornadoes flex into curved lines, cross over one another to for...