A customer looks at face masks in the antiflu section at a supermarket in Taipei.Pichi Chuang / Reuters

A few years ago, while doing research for my book on the beneficial microbes that share our bodies, I went on an inadvisably frenetic weeklong reporting trip that spanned five cities and three time zones. On the final night, I wearily picked up the phone in my hotel room to order some food, and noticed a label on the receiver. It said: Antibacterial handset. It was a perfect reflection of the world’s attitude to bacteria. They’ve existed for billions of years. They are everywhere, including within us. They influence our lives, safeguard our health, and shape our bodies. I had been traveling for days to learn more about them. And yet, even my phone wanted to kill them.

It wasn’t always like this. Antonie van Leeuwenhoek, the Dutchman who first discovered the microbial world in the late 17th century, was delighted to learn that multitudes of living things existed below the threshold of our perception. Even when he saw microbes in the plaque between his own teeth, he was more amazed than repulsed. Microbes only became synonymous with disease and disgust in the 19th century, when, in quick succession, biologists realized that bacteria caused illnesses like cholera, leprosy, gonorrhea, tuberculosis and more. And so they became villains: things we needed to destroy, lest they destroy us.

But a world without microbes is unachievable. Killer phones notwithstanding, microbes are simply too abundant and omnipresent to wipe out. Even cosmic events like asteroid collisions or supernova explosions are unlikely to do it; it would likely take nothing less than the death of our sun to truly sterilize the planet.

Which is fortunate, because the death of all microbes would be a really bad thing. In 2014, the microbiologists Jack Gilbert and Josh Neufeld published a thought experiment, in which they imagined what would happen if all the microbes in the world suddenly vanished. It’s a fun essay that draws upon two long-standing scientific traditions: working out how important things are by removing them and seeing what happens; and just using your imagination if actual experiments aren’t feasible.

You can see the consequences of this dystopian fan fiction in the video below—the seventh in a series of online films produced by HHMI Tangled Bank Studios, which adapt the stories in my book, I Contain Multitudes.