Flat-earthers oftentimes have a hard time understanding why Earth's atmosphere is "next to a vacuum" and doesn't get "sucked" by the vacuum. I explain the reason here . Oftentimes these same flat-earthers will use vacuum chambers as examples of how vacuum "sucks" air into it: The walls of the vacuum chamber are under enormous pressure, and if it's opened, it "sucks" air in very rapidly. This is a complete misunderstanding of what's happening. The actual reason why vacuum chambers experience an enormous amount of pressure by the surrounding air, and why the air rushes in at enormous speeds if it's opened, is very closely related to what I explained in that other article. To help understand, consider the atmosphere as if it were water. This is, in fact, not far-fetched because both liquids and gases behave in a fluid manner, quite similarly to each other. Their densities may be quite different, and this density behaves a bit dif...