0.0 0.1 0.2 0.3 0.4 0.1 0.2 0.3 0.4 Entropy for attractive fermions PSfrag replacements s/mµ T/µ FIG. 5: The entropy density s divided by mµ for attractive fermions as a function of T/µ . Since the pressure is determined by the average kinetic energy, and the ideal gas relation eq. (30) still holds for a unitary gas, the average kinetic energy per particle is just ϵ$_{1}$ = −F /n , eq. (31). Finally we obtain: where all the quantities in the above formula are the single component values of the last section. In terms of the scaling functions: For two-component fermions the available phase space I is doubled. The cross- section is halved since spin up particles only scatter with spin down. Finally the entropy is doubled. This gives η s = m $_{16}$√$_{2}$ F n ( ∂ F ∂T ) − 1 (72) η s = 3 $_{4}$√$_{2}$$_{π}$ c c ′ (2 c − µ T c $^{′}$) = π $_{4}$√$_{2}$ b b ′ (2 b − T $_{µ}$b $^{′}$) (73) ( η s ) fermi = 4 ( η s ) bose (74) 25