Superfluid
Superfluid is a universal phenomenon which means the state of matter in which the matter behaves like a fluid with zero viscosity. While originally this phenomenon was discovered in liquid helium, recently it finds applications not only in the theory of liquid helium but also in astrophysics, high-energy physics and theory of quantum gravity. The phenomenon is related to the Bose-Einstein condensation but not identical: not all Bose-Einstein condensates can be regarded as superfluids and not all superfluids are Bose-Einstein condensates.
Contents
Superfluidity of liquid helium
In liquid helium the superfluidity effect was discovered by Pyotr Kapitsa and John F. Allen. It has since been described through phenomenological and microscopic theories. In liquid helium-4 the superfluidity occurs at far higher temperatures than it does in helium-3. Each molecule of helium-4 is a boson particle, by virtue of its zero spin. Helium-3, however, is a fermion particle, which can form bosons only by pairing with itself at much lower temperatures, in a process similar to the electron pairing in superconductivity.
Superfluid in astrophysics
The idea that superfluidity exists inside neutron stars was first proposed by Arkady Migdal.[1][2] By analogy with electrons inside superconductors forming Cooper pairs due to electron-lattice interaction, it is expected that nucleons in neutron star at sufficiently high density and low temperature can also form Cooper pairs due to the long-range attractive nuclear force and lead to superfluidity and superconductivity.[3]
Superfluidity in high-energy physics and quantum gravity
Superfluid vacuum theory is an approach in theoretical physics and quantum mechanics where the physical vacuum is viewed as superfluid. The ultimate goal of the approach is to develop scientific models that unify quantum mechanics (describing three of the four known fundamental interactions) with gravity. This makes SVT a candidate for the theory of quantum gravity. It is hoped that development of such theory would unify into a single consistent model all fundamental interactions, and to describe all known interactions in the Universe, at both microscopic and astronomic scales, as different manifestations of the same entity, superfluid vacuum.
See also
- Macroscopic quantum phenomena
- Bose-Einstein condensate
- Superfluid helium-4
- Superconductivity
- Supersolid
- Quantum hydrodynamics
- Superfluid vacuum
References
Further reading
- Antony M. Guénault: Basic superfluids. Taylor & Francis, London 2003, ISBN 0-7484-0891-6.
- James F. Annett: Superconductivity, superfluids, and condensates. Oxford Univ. Press, Oxford 2005, ISBN 978-0-19-850756-7.
- G. E. Volovik, The Universe in a helium droplet, Int. Ser. Monogr. Phys. 117 (2003) 1-507.
| |||||||||||||||||||||||||
