<Dl> <Dd> β = γ / (δ − 1), ν = γ / (2 − η) (\ displaystyle \ beta = \ gamma / (\ delta - 1), \ qquad \ nu = \ gamma / (2 - \ eta)). </Dd> </Dl> <Dd> β = γ / (δ − 1), ν = γ / (2 − η) (\ displaystyle \ beta = \ gamma / (\ delta - 1), \ qquad \ nu = \ gamma / (2 - \ eta)). </Dd> <P> It can be shown that there are only two independent exponents, e.g. ν and η . </P> <P> It is a remarkable fact that phase transitions arising in different systems often possess the same set of critical exponents . This phenomenon is known as universality . For example, the critical exponents at the liquid--gas critical point have been found to be independent of the chemical composition of the fluid . </P>

The process of changing solid to liquid is called