# Chaplygin gas

### Chaplygin gas

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 p=-A/\rho^\alpha where p is the pressure, \rho is the density, with \alpha=1 and A a positive constant. The substance is named after Sergey Chaplygin.

In some models, generalized Chaplygin gas is considered, where \alpha is a parameter which can take on values 0 < \alpha \le 1.