Recently, superfluids have been used to trap and slow the speed of light. Superfluids are also used in high-precision devices, such as gyroscopes, which allow the measurement of some theoretically predicted gravitational effects (for an example see the Gravity Probe B article). Referred to as Superfluid Helium Droplet Spectroscopy (SHeDS), it is of great interest in studies of gas molecules, as a single molecule solvated in a superfluid medium allows a molecule to have effective rotational freedom - allowing it to behave exactly as it would in the 'gas' phase. Recently in the field of chemistry, superfluid helium-4 has been successfully used in spectroscopic techniques, as a quantum solvent. Once the first critical velocity is reached, the superfluid will very quickly begin spinning at the critical speed. That is, when the container is rotated at speed below the first critical velocity (related to the quantum numbers for the element in question) the liquid remains perfectly stationary. Instead of rotating uniformly with the container, the rotating state consists of quantized vortices. A second unusual effect is that superfluid helium can form a layer, a single atom thick, up the sides of any container in which it is placed.Ī more fundamental property than the disappearance of viscosity becomes visible if superfluid is placed in a rotating container. If a capillary tube is placed into a bath of superfluid helium and then heated, even by shining a light on it, the superfluid helium will flow up through the tube and out the top as a result of the Clausius-Clapeyron relation. (It is thus impossible to set up a temperature gradient in a superfluid, much as it is impossible to set up a voltage difference in a superconductor.) One of the most spectacular results of these properties is known as the thermomechanical or 'fountain effect'. The superfluid component has zero viscosity, zero entropy, and infinite thermal conductivity. A superfluid acts as if it were a mixture of a normal component, with all the properties associated with normal fluid, and a superfluid component. Superfluids, such as supercooled helium-4, exhibit many unusual properties. A unified description of superconductivity and superfluidity is possible in terms of gauge symmetry breaking. In it, Cooper pairing takes place between atoms rather than electrons, and the attractive interaction between them is mediated by spin fluctuations rather than phonons. On the other hand, helium-3 atoms are fermions, and the superfluid transition in this system is described by a generalization of the BCS theory of superconductivity. Specifically, the superfluidity of helium-4 can be regarded as a consequence of Bose-Einstein condensation in an interacting system. Helium-4 atoms are bosons, and their superfluidity can be understood in terms of the Bose statistics that they obey. Although the phenomenologies of the superfluid states of helium-4 and helium-3 are very similar, the microscopic details of the transitions are very different.

Fluid browser vs helium