Yet friction produces heat and thus an increase in entropy – which measures the amount of energy that cannot be used to perform work – and it therefore distinguishes past from future. The increase in entropy – the second law of thermodynamics – is the only law of nature that makes this fundamental distinction.
但摩擦力产生热量并因此导致熵的增加——熵代表一种测量在动力学方面不能做功的能量总数——并因此将过去和未来区分开来。而熵的增加——热力学第二定律——则是唯一个描述这一基本差别的自然定律。