In a peer learning group, I was tasked with explaining "how vacuums work". I had one hour to learn about the topic. And one hour to teach it. This is a write-up of my learnings.

But hold on — By "vacuum", are we talking about vacuums in physics, or vacuum cleaners the household appliance?

Mostly the latter. But the two are closely related.



Ideal Vacuum

A vacuum is space devoid of matter.

That is, space where there is literally nothing .

In practice, a perfect/ideal vacuum is really hard to achieve. Instead, we get imperfect approximations known as "partial vacuums".

Vacuum cleaners are an example of a partial vacuum.



Pressure Difference

A partial vacuum has a lower air pressure than atmospheric pressure. And gases move from high-pressure areas to low-pressure areas. Where there is "Nothing", "Something" will quickly find its way there.

This pressure differential is what makes vacuum cleaners work.



What's In a Vacuum Cleaner?

That's really all the parts you need for a basic vacuum.

Here's a tutorial for a DIY vacuum cleaner, made with a plastic water bottle:



Early Vacuums

The earliest versions of vacuum cleaners were invented in the 1860s in the US. They were manual models that required cranking/pumping.

The Hoover Company, one of the earliest and most successful makers of vacuum cleaners, became a household name. Many people simply use the word "hoover" as both a noun and a verb. The same way "Bing" became synonymous with searching the web.



Similar Phenomena in Daily Life



Does a Fan Work in a Vacuum?

Well, if a vacuum is space with no stuff . And a fan works by moving stuff around. Then what would happen if we use a fan in a vacuum

The short answer is — not really! This is a fascinating demo:



Vacuum Outside of Physics and Engineering

"Nothingness" is so interesting that thinkers around the world have been thinking/debating about it for a long time.

It has been documented in Greek philosophy (works by Plato and Aristotle). Chinese philosophy ("Wu" in Taoism). And by Islamic scholars (Al-Farabi). The list goes on.



One More Question 

I'll leave you with a question I've had for a long time. Namely, "why is a vacuum cleaner so f**king loud!?"

Turns out it's the fan. You need a fan that's big and powerful enough. And cheap enough to mass manufacture at a reasonable price point.