@rabinoz :
I guess there are plenty of other "models" to explain how the Earth, or the Universe, works : it may be pretty hard to decide which is the right one ; sounds like "religion" matters, to me. So, for the moment, I'll keep regarding the RE model as the "right one", as you do, it seems.
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In the original post, I asked the following question :
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"3) Another question, related to "air pression" :
If I put 1 gallon of water in a barrel, and close the barrel : it's the upper surface of the barrel that will determine the pression ( air ) it will be subjected to, right ? And that determines what they call "weight" in RET, right ?
Then, I take the same barrel, and put 100 gallons of water in it : the upper surface of the barrel is still the same. Then it should weigh the same, right ?
Yet, you can easily verify it's not true..."
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There's something more :
How come objects don't levitate ? Indeed, if you take an object, lift it a bit, then let go of it : how come that object won't stay still "up in the air" ? Why does it have to "fall" ? I mean, the air pressure is the same below AND above the object, so, the denpressure theory implies that the object should stay where it is : and, in fact, the higher you go, the lower the air pressure, so... objects should "fall" upwards, NOT downwards !
And, anyway, what does "upwards" and "downwards" mean, in the "denpressure theory" ? I mean : why should air molecules move toward the surface of the Earth, rather than heading toward "the sky" ? One could tell me : "Because : the air exerts a pressure on itself, due to its weight" ; Ok, I know that, but... this is RE theory, NOT FE theory. Again, according to FE theory, the closer to the Earth, the higher the pressure of the air, so : it should be the air next to the surface of the Earth that exerted a pressure on the air above it : air should "fall" upward.