If you twirl a glass syringe, it spins quite nicely, lubricated on a micron-thin layer of air. This is an example of a hydrodynamic bearing, a device where the viscosity of a fluid and relative motion of two closely-spaced surfaces provides the cushion necessary to keep the surfaces separate. In this video, Steve Mould explains the phenomenon in more detail and shares some awesome examples of this hydrodynamic levitation in action. (Image and video credit: S. Mould; submitted by clogwog)