Superfluid
Definition and meaning of Superfluid in chemistry.
A superfluid is a highly exotic state of matter in which a cryogenic fluid flows with exactly zero measurable viscosity, meaning it moves without any loss of kinetic energy to internal friction. This remarkable quantum state only occurs at extreme temperatures approaching absolute zero.
In more detail
When a specific fluid like the isotope liquid helium-4 is cooled rapidly below its critical lambda point, it fully transitions into becoming a superfluid. In this unusual state, it visibly exhibits bizarre quantum macroscopic phenomena, such as spontaneously creeping up and over the steep walls of its container and remaining completely, perfectly motionless if its physical container is slowly rotated. Superfluidity is theoretically and physically very closely related to the phenomenon of Bose-Einstein condensation, where a large macroscopic fraction of bosons collectively occupy the lowest possible quantum energy state.
Key facts
| Field | Physical Chemistry |
|---|---|
| Formula | He |
| Defining trait | Exactly zero internal viscosity |
| Condition | Temperatures extremely close to absolute zero |
The stable isotope liquid helium-4 reliably becomes a frictionless superfluid when cooled below its lambda point of exactly 2.17 Kelvin.
Frequently asked questions
Can a frictionless superfluid be successfully contained in an open glass cup?
No, a true superfluid will quickly form a microscopic thin film and spontaneously creep up and over the vertical walls of any open container to escape.