0 Vacuums and a Vacuum

One of the wonders of the English language, and an aspect that is fairly unique compared to other languages, is how the same word and spelling can have different meanings (known as a homonym). Such is the case with the word "vacuum." Webster's Dictionary gives four different definitions for the term, but these can basically be boiled down into two different sets. The first is "a space absolutely devoid of matter." This phrase is used primarily in science, astronomy, and physics. To the layperson, this form of a vacuum rarely comes into play. The second is "a device creating a partial vacuum," which refers to machines that we commonly refer to as vacuums, with most American homes owning some form of a vacuum cleaner. These terms refer to different things, but the latter actually relies on the former to operate.

Let us focus first on the scientific and physics definition of vacuums. You probably remember your high school science teacher referring to how certain aspects of science hold true in a vacuum. For example, all objects would fall at the same rate in a vacuum regardless of weight, but in practice this is not true. Air resistance can lead to a piece of paper falling much more slowly than a bowling ball. A perfect vacuum is an area with absolutely no particles in it at all - this includes any form of air (gas). On Earth, it is almost impossible to achieve. Even in space, the occurrence of a total vacuum may be rare. Scientists are constantly discovering new things such as dark matter that make it more likely that even visible voids in space may contain particles of something. However, in laboratories, partial vacuums can be created that are void of enough particles to produce experiments that would behave very similar to how they would in a complete vacuum.

The vacuum cleaner, meanwhile, takes advantage of the vacuum in physics terms to create suction. This is done by creating pressure differentials that lead to air flowing from one area to another. Fluid dynamics dictates that air will flow from a region of high pressure to that of low pressure. For an example, think of the movies when a door is opened into outer space and everything inside the ship jets out. This occurs because the ship is higher pressure and outer space is low pressure. By creating a low pressure area within the vacuum cleaner, a small amount of air is sucked from outside in, creating suction at the end of the nozzle all the way into the canister. By this notion, the whole concept of suction (sucking) is actually a misnomer when applied to a vacuum cleaner. In reality, the air and lighter particles it surrounds (preferably dirt) is actually being pushed from the higher pressure area outside the cleaner into the storage canister.

It is interesting to see how physics terms relate to the devices we use every day. Now, you have some level of understanding of the relationship between voids in outer space and cleaning up your dirty floor.

Information on vacuum in space from BBC News. Another type of product using vacuum technology would be vacuum mixers.