Question

Why we are not crushed by the pressure created by a thick layer of atmosphere?

Answer 1

It's true that the weight of the column of air above us is very heavy. We can call this weight an external pressure, because it is pushing down on us. However, the reason we, nor other objects, are crushed by the weight of this air is because this external pressure is balanced by our internal pressure, which arises from various fluids and materials we are composed of. This internal pressure exists because we are largely made up of incompressible solids and liquids. To simplify matters, just think about a balloon filled with water. The external pressure is trying to compress the balloon, while the water inside the balloon is able to balance this external pressure due to the relative incompressibility of water. This incompressibility is responsible for the internal pressure opposing the external pressure.
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