There is one thing that puzzles me: common explanation of why don't structures collapse under the enormous atmospheric pressure (~101300N/m^2) is that the force pushing from inside balances out the force pushing from outside.
Now let's imagine a cube made of imaginary airtight perfectly flat polystyrene with side length of 1m. It would have a wall thickness lets say 0.2m so the inside of the cube would be a cube with side length of 0.6m. If this explanation of 'forces balancing out' is to hold - than there should be a net force of F=(A1-A2)*Patm in place - >> F=[(6*1^2)*101300-(6*0.6^2)*101300=388,992N which should surely crush any such structure, but this clearly doesn't happen...
I have attached illustrative picture.
Sorry for triviality of the question - it's just it somehow doesn't make sense to me. Can anyone please help?