Mechanical properties of the thermal equilibrium Friedmann-Robertson-Walker universe model

The mechanical property of the thermal-equilibrium Friedmann-Robertson-Walker (TEFRW) universe is first studied. The equation of state and the scale factor of the TEFRW universe take the forms of w=w(a;z_T) and a=a(a;z_T,H₀). For the universe consisting of the nonrelativistic matter and the dark energy, the behavior of the dark energy depends on the value of the present-day matter fraction. For the TEFRW universe consisting of N ingredients, the effective temperature is introduced. Lastly, a simple TEFRW universe model is analyzed.