Until recently most astronomers believed that the space between the galaxies in our universe was a near-perfect vacuum.

直到最近，大多数天文学家都认为我们宇宙中星系之间的空间是近乎完美的真空。

But low-Earth orbit isn't a perfect vacuum.

但近地球轨道不是一个完美的的真空。

In contrast to the mechanism of conduction and convection , radiation may take place in a perfect vacuum.

与传导和对流的原理不同，辐射可在完全真空中进行。

It commonly used to valve lever seal request strict situation, if USES in the perfect vacuum in the situation and the nuclear industry.

它常用于对阀杆密封要求严格的场合，如用于高真空的场合和核工业中。

Vacuum may be thought of as the absence of pressure. It is the measure of negative pressure between standardized atmospheric pressure and a theoretically perfect vacuum.

真空可以被认为缺少压力。真空是以标准大气压的负压和理论完全真空来测量的。