critical mass

1. N-SING In physics, the critical mass of a substance is the minimum amount of it that is needed for a nuclear chain reaction. 臨界質量[技術] [also no det]

In order to make a nuclear explosion, the critical mass must come together within a fraction of a millionth of a second. 爲促成一次核爆炸，臨界質量必須在一百萬分之一秒內聚集在一起。

2. N-SING A critical mass of something is an amount of it that makes it possible for something to happen or continue. 臨界數量[also no det]

Only in this way can the critical mass of participation be reached. 衹有這樣才能湊足蓡加人數。