Originally Posted by P A N

2nd question: Can a situation or experiment be cited as evidence that an enclosed system of gases can exist within a vacuous surrounding without a barrier or seal?
Answer: "Gravity"

personally, i'm not happy with the answer on the second one. gravity cannot be proven to exist. it is accepted as fact, which is very different from being fact. the reason we need gravity is so we don't fall off the ball. to a flat earther, this translates to "we need an imaginary force to describe the utterly anomalous ball-earth characteristics such as curved water and a gas existing next to a vacuum." obviously, i asked this question to say this. there is no other example of gasses existing next to vacuums that we can test. we rely on the space program for this knowledge.

Originally Posted by Wikipedia

A reduced-gravity aircraft is a type of fixed-wing aircraft that provides brief near-weightless environments for training astronauts, conducting research and making gravity-free movie shots.