In a spherical container, if the molecular mean free path is greater than the diameter of the container, can it be considered a vacuum?
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I would like to ask, how should this issue be considered?
If the molecular free path is greater than the size of the device, the number of molecules is very low compared to the volume of the container; in that case, it can be considered a vacuum as well! Hehe, it’s just my humble opinion – as long as everyone discusses more.
The molecular free path is the distance between collisions between molecules, whereas pressure is related to collisions between molecules and the container walls; therefore, strictly speaking, even if the number of molecules is low, a large momentum of those molecules can still result in high pressure.