The universe began in a Big Bangabout 13.7 billion years ago and has been expanding at an ever accelerating rate ever since.
宇宙大爆炸理论起始于137亿年以前，而且一直都以非常快的速度在扩张。
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For almost a century, the Universe has been known to be expanding as a consequence of the Big Bangabout 14 billion years ago.
近一个世纪以来，人类知道宇宙因为140亿年左右前的那次大爆炸而在膨胀。
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Other groups are looking for even earlier clues in the cosmic microwave background, the leftover radiation from the Big Bangabout 13.7 billion years ago.