From the viewpoint of cosmological evolution it seems that the optical variation of QSOs becomes more violent with the cosmological time, and finally it connects itself with that of active galaxies.

从宇宙演化的角度来看，类星体的光变随着宇宙时愈演愈烈，最后与活动星系相接。

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Another exception is the "cosmological arrow of time," which points forward from the Big Bang in the direction of the universe's expansion.

另一个例外是“时间的宇宙箭头”，该箭头从大爆炸指向宇宙膨胀的方向，其可能与热力学箭头相连，指向宇宙最终的热寂。

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To return to the arrow of time, there remains the question: why do we observe that the thermodynamic and cosmological arrows point in the same direction?

回头再说时间箭头，余下的问题是；为何我们观察到热力学和宇宙学箭头指向同一方向？

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