Vacuum is nothing. The word vacuum is defined as “a space entirely devoid of matter”. Taken literally this is something so physically difficult to achieve. Most scientists and physicists say it’s impossible. The only natural vacuum that we know of in the universe is space – and technically that’s not even a real vacuum since there are many other things in it (things like planets and even small particles). What this means is that ‘complete’ or ‘100% vacuum’ is only theoretical.
Achieving Small Amounts of Vacuum
It’s pretty easy to create a small amount of vacuum. For instance: the noise created by clapping one’s hands together actually results from the creation and subsequent exhaustion of a small amount of vacuum. To maintain this vacuum without exhausting it, however, is much more difficult.
Aristotle actually noticed this thousands of years ago. He noted that “nature abhors a vacuum” essentially predicting what modern advanced scientific techniques and systems would prove much later. Defining vacuum properly requires a bit of a dive into some basic physics and scales of measurement. These are simply measures of pressure. The physics part of this becomes very complicated very quickly – so bear with me for this next part.
3 Systems of Measurement for Vacuum
There are 3 systems of measurement for Vacuum: Torr, mbar, and Pa. There are a few reasons why these three scales exist, but we will keep it simple for now. Torr is widely used in the vacuum industry and is sometimes referred to as “millimeters of mercury” or “inches of mercury” [1].
Mbar is used when referring to atmospheric pressure, and subsequently is the scale used in meteorology science.
PA is the official SI [2] unit for vacuum pressure and as a result it is widely used in the study of physical sciences. Most measurements are taken in mbar, so we will try to stick to that when describing various pressures. Here’s a handy scale to put things in perspective for the next part.
