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第19行：
第19行： − 在微观尺度上进行研究时，上述判断是不能作出的。观察一个被空气冲击的单个烟雾粒子，我们不清楚视频是正向播放还是反向播放，事实上，这是不可能的，因为适用的定律显示了 t 对称性，因为它向左或向右漂移，它看起来没有什么不同。只有当你在宏观研究气体时，熵的影响才会变得明显。平均来说，你可以预期点燃的火柴周围的烟雾颗粒会相互漂移远离，扩散到整个可用空间。这将是一个天文学上不可能的事件，所有的粒子聚集在一起，但你不能评论任何一个烟雾粒子的运动。+ 第26行：
第26行： − − 相比之下，某些涉及弱核力的亚原子相互作用违反宇称守恒，但这种情况很少发生。根据 CPT 定理，这意味着它们也应该是时间不可逆的，因此建立了一个时间箭头。然而，这既与时间的热力学箭头无关，也与时间不可逆性的日常经验无关。 +
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When studying at a microscopic scale, the above judgements cannot be made. Watching a single smoke particle buffeted by air, it would not be clear if a video was playing forwards or in reverse, and, in fact, it would not be possible as the laws which apply show T-symmetry, as it drifts left or right qualitatively it looks no different. It is only when you study that gas at a macroscopic scale that the effects of entropy become noticeable. On average you would expect the smoke particles around a struck match to drift away from each other, diffusing throughout the available space. It would be an astronomically improbable event for all the particles to cluster together, yet you cannot comment on the movement of any one smoke particle.
When studying at a microscopic scale, the above judgements cannot be made. Watching a single smoke particle buffeted by air, it would not be clear if a video was playing forwards or in reverse, and, in fact, it would not be possible as the laws which apply show T-symmetry, as it drifts left or right qualitatively it looks no different. It is only when you study that gas at a macroscopic scale that the effects of entropy become noticeable. On average you would expect the smoke particles around a struck match to drift away from each other, diffusing throughout the available space. It would be an astronomically improbable event for all the particles to cluster together, yet you cannot comment on the movement of any one smoke particle.
在微观尺度上研究时不能做出上述判断。观察单个烟尘颗粒被空气反复冲击时，我们不清楚视频是正放的还是倒放的，其实也不可能分辨出来，因为适用的定律显示了t对称，也因为它向左或向右漂动看起来没有什么不同。只有当你在宏观尺度上研究气体时，熵的影响才会变得明显。平均而言，你会认为被擦过的火柴周围的烟尘颗粒会彼此远离，扩散到整个空间。所有的粒子都聚集在一起是一个极不可能的事件，你也不能解释任何一个烟雾粒子的运动。
By contrast, certain subatomic interactions involving the weak nuclear force violate the conservation of parity, but only very rarely. According to the CPT theorem, this means they should also be time irreversible, and so establish an arrow of time. This, however, is neither linked to the thermodynamic arrow of time, nor has anything to do with the daily experience of time irreversibility.
By contrast, certain subatomic interactions involving the weak nuclear force violate the conservation of parity, but only very rarely. According to the CPT theorem, this means they should also be time irreversible, and so establish an arrow of time. This, however, is neither linked to the thermodynamic arrow of time, nor has anything to do with the daily experience of time irreversibility.
相比之下，某些涉及弱核力的亚原子相互作用却很少违反宇称守恒定律。根据CPT定理，它们也应该是时间不可逆的，从而建立了一个时间箭头。然而，这与时间的热力学箭头无关，也与具有时间不可逆性的日常经验无关。
{{unsolved|physics|[[Arrow of time]]: Why did the universe have such low entropy in the past, resulting in the distinction between [[past]] and [[future]] and the [[second law of thermodynamics]]?}}
{{unsolved|physics|[[Arrow of time]]: Why did the universe have such low entropy in the past, resulting in the distinction between [[past]] and [[future]] and the [[second law of thermodynamics]]?}}