A frictionless flow emerges from the quantum nature of ultracold atoms.
It seems rather strange: A fluid that, once it is stirred, never comes to rest again. From our experience, we expect friction to render such a thing impossible. At extremely low temperatures however, atoms exhibit quantum effects and move in perfect unison. This creates a frictionless fluid where vortices, or swirling patterns, can persist indefinitely without dissipating. Superfluidity can be studied for example in liquid Helium and is a fascinating property of matter that has implications in various fields, including physics and materials science.
The weird properties of a superfluid.