Photo by Ian Espinosa on Unsplash

A Mental Model for Germs

Germs are small, sticky, and omnipresent

The Apollo 11 astronauts spent 3 weeks in quarantine after returning to Earth. That’s because we didn’t know if moon germs existed. More than that, we didn’t know if moon germs could kill everyone on Earth. No matter how small the probability, the risk was big enough to enforce the quarantine. Scientists at NASA played it extra-safe.

Since we can’t see them, we don’t pay much attention to them. There’s nothing to pay attention to. The scale is different and we have trouble imagining it. This leads to some pretty incorrect ideas of how germs work.

I was worried about this. I didn’t understand how germs work. When I blow food that falls on the floor, do I get rid of germs? Why not? How does my mobile phone get dirtier than a toilet seat? Why don’t I get sick travelling in the tube everyday? I touch the same bar hundreds of other people do. How do germs transfer from anything I touch to my hands? Same for the food that fell? Is the three second rule valid?

I’ve found some answers.

First, let’s build some intuition for how small germs are, and how to think like a germ. It’s almost impossible for us to close the distance: how do we even go about seeing something that is invisible to our eyes, let alone thinking like that? We’ll use a…