Even 15 billion years or so after the Big Bang, echoes of that event still linger in the form of background radiation, only a few degrees above absolute zero.

• 大爆炸后的大约15亿年后，大爆炸的回声还没有消逝，它们以背景辐射的形式存在着，其温度大概只比绝对零度高几度。