Letters

Superfluid’s roots
I’m confused. A little. I thought that a Bose-Einstein condensate occurred only in a gas and that the first time it was achieved was in 1995 using rubidium atoms. “A matter of solidity” (SN: 9/11/10, p. 22) states, “Superfluidity arises when the atoms in superfluid helium join up in a quantum state called a Bose-Einstein condensate.”