The Vacuum of Space
The vacuum of space is the result of gravity. Our earth's gravity has pulled oxygen, nitrogen, and all of the other gases that make up our atmosphere with great efficiency. This atmosphere is what is pressing on your skin. As you go up in height, like in an airplane, the pressure slowly gets lighter and lighter. Thus airplanes have a pressurized cabin which keeps the inside of the plane at a constant pressure as if it were on the ground. The same is for spaceships, or the International Space Station, the astronauts must have complex life support systems to keep the pressure constant, air to breath clean and the correct oxygen levels.
In space however there is a near perfect vacuum. No air, no molecules, no H2O (water vapors) no N2 (nitrogen) no O3 (ozone). Thus nothing pressing all around you.
At ground level and with a normal weather day, no storms which disrupts the air pressure, we typically have an atmospheric pressure at sea level on the Earth is 1013.25 millibars, or about 14.7 pounds per square inch.
Let me repeat this... 14.7 pounds per square inch! That is a lot of pressure on your skin!
Supplies
I will use a hand operated vacuum and a rubber resealable cork.
A glass jar with hole drilled into the top
Soda can, new unopened
Marshmallow, small
Balloon, with minimal air in it and tied closed
Experiment One, the Balloon
The Balloon
As shown in this short video, the air pressure we blow into a balloon forms the balloon and has a higher pressure in the balloon than in the atmosphere which we know on average is 14.7 pounds per square inch. So as the balloon gets bigger, the pressure inside the glass jar reduces and the balloon grows because the air has a higher psi pressing outward.
Experiment Two, the Marshmallow
The Marshmallow
Taking the pressure from a chamber reduces the pressure on the 'skin' of the marshmallow, thus causing the pressure inside to push outward equally making the marshmallow grow in size.
The close up picture shows an unvacuumed next to a vacuumed marshmallow.
When the pressure is allow back into the chamber, it is crushed back into a wrinkly unrecognizable form.
(But they still taste yummy!)
Example Three, Soda
Soda
This short video (link above) shows how the vacuum 'pulls' the CO2 out of the sugary drink.
There is a fizz or a pop when you open a can of soda, that is because there is CO2 or carbon dioxide, a chemical compound occurring as a colorless gas with a density about 53% higher than that of dry air. Thus when under a vacuum, all of the bubbles come to the surface and the soda becomes flat.
Conclusion
The vacuum of space as shown, can make normal everyday items act very differently. Without air pressure we would not be able to breathe the oxygen we need to sustain life. A can of soda once opened would become flat quickly, and marshmallows would never be the same, as the little fluffy treats we know on earth.