从物理角度来说，真空是指完全没有物质。实际上，它不会以其纯粹的形式出现。对于技术应用，标准 DIN 28400 第 1 部分将真空定义为低于 300 毫巴的气压，这意味着低于地球表面可能出现的*低大气压。

　　原文：

　　In physical terms, a vacuum is the total absence of matter. In practice, it does not occur in its pure form. For technical applications, the standard DIN 28400 part 1 defines a vacuum as gas pressure less than 300 mbar, that means, less than the lowest atmospheric pressure that can occur on the surface of the earth.