The key to forming a black hole is cramming enough mass or energy into a small enough volume as happens when a massive star collapses.
形成黑洞的关键环节，就是要像脉冲星崩溃时出现的情况一样，把足够大的质量或能量压缩到足够小的体积。
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Scientists using this theory to trace our universe backward in time have found that its beginning point had a minimum volume that is not zero and a maximum energy that is not infinite.