I noticed how you said a low pressure inside.
Yes, because that provides a very clear example, where it is pushed up by the atmosphere. It allows a very simple visual indication.
If the atmosphere didn't push it up, its pressure wouldn't matter and the membrane wouldn't curve up into the object.
The only way for the membrane to curve up into the container from the bottom is if the pressure below is pushing up, or if you instead ditch your prior claims and have the low pressure inside magically suck it up.
You don't know how it all works.
That's right. I know it doesn't work.
Do you know one thing which really helps show that?
You repeatedly insulting me and claiming I don't understand rather than providing an actual answer to the issues raised.
Then there is you repeatedly just dismissing things as "other issues" without providing any justification for why it is.
You're jumping from one issue to another
No, we aren't.
The issue is the atmosphere below an object pushing into it, which would push it up if there is force balancing it.
This was initially brought up in regards to objects falling, but the key issue, the atmosphere pushing up from below an object, still applies here.
In my example, the membrane is clearly being pushed up by the atmosphere. In the cup example the same applies, with the sheet (and by extension the water) being pushed up by the atmosphere below. Although in this case one could argue it is just not being pushed down, but the sheet is still exposed to a large region of the atmosphere above and thus should still be pushed down. We can also extend the test by removing the sheet and having the water pour out of the glass, showing that was clearly being pushed down as well (even though that makes no sense in your model).
Now how about you address the issues?
Why do things fall?
We know it isn't simply because they exist in the atmosphere. This is because the atmosphere pushes from all sides, including from below as shown in my membrane example.
As the pressure mostly equalises that will result in no significant force.
We know it isn't the static pressure gradient in the atmosphere as that has a higher pressure below the object and thus pushes it upwards.
We know it isn't based upon moving the object as that would push it back, now down.
So it sure seems like the air isn't what is causing things to fall.