# Chaplygin gas

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Chaplygin gas,[1][2] which occurs in certain theories of cosmology, is a hypothetical substance that satisfies an exotic equation of state in the form ${\displaystyle p=-A/\rho ^{\alpha }}$, where ${\displaystyle p}$ is the pressure, ${\displaystyle \rho }$ is the density, with ${\displaystyle \alpha =1}$ and ${\displaystyle A}$ a positive constant. The substance is named after Sergey Chaplygin.

In some models, generalized Chaplygin gas is considered, where ${\displaystyle \alpha }$ is a parameter, which can take on values ${\displaystyle 0<\alpha \leq 1}$.

## References

1. ^ Kamenshchik, Alexander Yu.; Moschellai, Ugo; Pasquier, Vincent (2001), "An alternative to quintessence", Phys. Lett. B, 511 (2–4): 265, arXiv:gr-qc/0103004, Bibcode:2001PhLB..511..265K, doi:10.1016/S0370-2693(01)00571-8
2. ^ Bento, M. C.; Bertolami, O.; Sen, A. A. (2002), "Generalized Chaplygin gas, accelerated expansion and dark energy-matter unification", Phys. Rev., 66 (4): 043507, arXiv:gr-qc/0202064, Bibcode:2002PhRvD..66d3507B, doi:10.1103/PhysRevD.66.043507