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.