如果兩個(gè)熱力學(xué)系統(tǒng)中的每一個(gè)都與第三個(gè)熱力學(xué)系統(tǒng)處于熱平衡(溫度相同)，則它們彼此也必定處于熱平衡。這一結(jié)論稱做“熱力學(xué)第零定律”。(zeroth law of thermodynamics:The zeroth law states that if two systems are in thermal equilibrium with a third system, they are also in thermal equilibrium with each other.)
