Extremely cold drop of helium can be levitated forever

A drop of liquid helium cooled to a particularly low temperature might be made to drift in a vacuum for an indefinitely very long time. On this state, it may function a robust mini-laboratory for basic physics.

At -269°C, liquid helium is already surprisingly chilly for a liquid, however when it’s roughly 2 levels colder it turns into even stranger. At this temperature, quantum results make its viscosity vanish and switch it right into a superfluid. Charles Brown at …