Space is not a vacuum, that is a misperception and often poorly communicated by idiot narrative moron scientists with their book degrees.
If you have a mass falling towards a center, the density of the mass is decreased further from center. Pressure (to us) then exists by falling within the threshold.
Worse about both those things is the Standard Model is wrong and Quantum Mechanics is an absolute grant fed larp -- so the conditions at which the above actions exist is better explained by variable field collision density or Resistance Field Theory.
Bear in mind that the explanation you posted is not official -- it is one model and it is incomplete. At present, the very same scientists who tell you that model is correct can also not explain what 89% of what the universe consists of -- and also can not explain how the Standard Model of particle physics seems to contain endless primary particles (bcz SM is wrong)
Again --> do not rely on the current theories as being leverage to dispute. They are are muddled as the opposition theories.
As to your "physical barrier" -- again, falling, not pressured like expansion. The atmosphere is not some fixed bubble but a gradient.
"officially"
Bear in mind that the explanation you posted is not official -- it is one model and it is incomplete. At present, the very same scientists who tell you that model is correct can also not explain what 89% of what the universe consists of -- and also can not explain how the Standard Model of particle physics seems to contain endless primary particles (bcz SM is wrong)
Again --> do not rely on the current theories as being leverage to dispute. They are are muddled as the opposition theories.
As to your "physical barrier" -- again, falling, not pressured like expansion. The atmosphere is not some fixed bubble but a gradient.