Superfluiditeetti

Superfluiditeetti is a state of matter that exhibits zero viscosity. This means that a superfluid can flow without any internal friction. When a superfluid is placed in a container, it will spontaneously flow up the sides and over the edge, a phenomenon known as the fountain effect or the thermomechanical effect. Superfluidity is a quantum mechanical phenomenon that occurs at very low temperatures, close to absolute zero.

The most well-known superfluid is helium-4, which becomes superfluid below a temperature of about 2.17 Kelvin (K). This transition temperature is known as the lambda point, denoted by the Greek letter lambda (λ), because the specific heat capacity of helium-4 exhibits a sharp peak at this temperature, resembling the shape of the Greek letter. Other isotopes of helium, such as helium-3, can also become superfluid, but at much lower temperatures and through a different mechanism involving Cooper pairing, similar to superconductivity in metals.

The lack of viscosity in superfluids has several remarkable consequences. For instance, a superfluid stirred in a beaker will continue to flow indefinitely without slowing down. Superfluid helium can also creep along surfaces, defying gravity. This peculiar behavior arises from the collective quantum mechanical nature of the atoms in the superfluid state, where they behave as a single quantum entity. Understanding superfluidity is crucial for advancements in quantum physics, cryogenics, and the development of sensitive scientific instruments.