Thermodynamics is the study of how particles react and how energy works in a system. There are four facts that hold true in every thermodynamics situation: - If two systems are in thermal equilibrium with a third system, then they are in thermal equilibrium with each other. - Heat and work are forms of energy transfer. - Entropy in a system not in thermal equilibrium increases. - Entropy in a system approaches a constant as temperature approaches zero. These ideas are most likely called