I am trying to gain a better understanding of thermodynamic equilibrium. Here's what (I think) I know:
If a system is in Thermal, Radiative, Chemical, and Mechanical Equilibrium, then it is in thermodynamic equilibrium. When in this state, the system can do no work as there is no available free energy to use. And when a system is in this state it is at its maximum entropy.
Please correct me if any of that is incorrect.
What I want to know is what would something look like if it was in thermodynamic equilibrium? Say a bit of matter like a rock was hypothetically in this state, would it still be a rock, but with uniform heat throughout, no net force, no net radiation and no net reaction? Or would it have changed state to become a gas? (because the entropy of gas is higher than that of a solid) Or would the rock just be heat energy? (I say this because the Heat Death of the universe suggests that everything would just be heat energy, no matter, and in thermodynamic equilibrium)
Any of your help on any of these questions would be extremely useful.
Thank you.