Why does atmospheric pressure not crush us

You can test this theory by buying balloons of different skin thickness and seeing which one pops first. The maximum size before popping should correlate with the thickness of the balloon skin measured before blowing up.

You will need to use a micrometer to measure the thickness of the balloon. It is because we have evolved so that our internal pressure matches the atmospheric pressure, so we are in equilibrium.

When you go up in an airplane, your ears tend to hurt until you can get them to pop because, at that altitude, your internal pressure is greater than the external pressure, so until you can get your ears to "pop" - that is, your internal pressure to equalize with the external pressure, you feel pain.

Now, because physicists always like to think of what happens in the extreme, let's ask: knowing that your internal pressure is equalized by evolution to atmospheric pressure of And then all the liquid in your body would instantly freeze. You guessed it: you would implode due to the excessive external pressure! We are being pressed equally from all directions,including internally.

The air inside of your lungs is at the same pressure as the air outside, so it presses your chest cavity outward with the almost same force as it is being pressed inward slightly less, because there is more surface area on which pressure is applied outside than in, and that is why you exhale when you relax.

As for the rest of your body, it's mainly made up of water, which is a liquid and not a gas. Liquids are incompressible: they push back with the same pressure that is pressed upon them by themselves. As a result, your head does not get crushed down against the sidewalk. In this way, the fluid nature of air makes it so that the weight of the atmosphere pushes everywhere in on you, but does not push you down.

This canceling of forces on your hand only happens if atmospheric air is able to reach both the palm and the back of your hand. If you remove the air that is pushing up on the back of your hand, there will no longer be a canceling of forces and you will experience 10 bowling balls worth of weight on your hand overall. You can partially do this by turning on an extremely strong vacuum machine while pressing the opening at the end of the hose directly against the back of your hand.

The vacuum machine sucks and removes the air that was pressing on the back of your hand, allowing your hand overall to feel the downward force of the air pressure on the palm of your hand. You would probably describe this experience as the hose sucking your hand down towards it, and therefore would say that the force that your hand overall feels is a pulling force exerted by the hose.

In reality, the weight of the air above your hand is pushing your hand down towards the vacuum hose and is the source of the force. Any time we talk about suction we really mean removing the air from one side of an object so that the immense weight of the air in the atmosphere can be experienced by the object overall without being canceled. Any time you have had difficulty removing a suction cup from a window, that resistive force you are experiencing is literally the weight of the atmosphere's air crushing it against the glass.

If the suction cup is large and has a good seal, you will not be strong enough to directly pull the cup off. Simply put, you are not strong enough to oppose the force of the air crushing the suction cup against the glass. However, you can get the suction cup off of the window easily by letting atmospheric air get to the other side of the suction cup. Poke a pencil or pin in between the cup and the glass to break the seal, thereby letting air flow behind the suction cup.

Once this happens, the forces on the cup from the air on both sides cancel each other and the cup is no longer crushed against the glass. With these concepts in mind, it should now be obvious that suction cups don't work in the vacuum of space.

Even when the force of the air on the back of your hand cancels the force of the air on the palm of your hand, your hand is still getting crushed in the middle between these two opposing forces. Fortunately, there is also pressure inside your hand directed outwards which cancels the inward force of air pressure. As a result, there is no net force on the surface of your hand. The internal pressure is not caused by air but is caused by trapped water. Internal body pressure is created and maintained by having semi-rigid cells that are pumped up with water using the chemical attractive forces between water and ions such as sodium.

Each cell is a bit like a water balloon. If you pump water into a balloon, the internal water pressure can cancel out the external air pressure and the balloon holds its shape without being crushed.

Even if they were not, atmospheric pressure is certainly not enough to get our bones crushed. When a diver is 10m under water, the pressure is doubled Pa.

Any recreational diver can do that. I have been deeper than that, without any ill effects. At m, the pressure is 10 times atmospheric pressure, and only specially trained divers, with special equipment including breathing gas that has nitrogen reduced and replaced by some other gas like helium can go there.

The deepest verified dive is m - about 32x atmospheric pressure. Fish and other marine creatures have their internal body pressure the same as the water around them. As a result, even in the deepest oceanic trenches there is life. The reverse is more dangerous.

If our body was exposed to vacuum, the internal pressure would quickly kill us, as explained in this question. There are five good answers in this link:. 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.