Liquid helium superfluid. 4:10 video.
https://www.youtube.com/watch?v=YVMuI_shltE
Previously:
https://www.homemadetools.net/forum/...538#post170195
https://www.homemadetools.net/forum/...277#post154148
https://www.homemadetools.net/forum/...059#post203180
https://www.homemadetools.net/forum/...250#post150146
https://www.homemadetools.net/forum/...4677#post80364
