system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5; How do we know atoms exist?

Like obviously they exist. We can measure them, split them and manipulate them. But like, how?
gpt
In fact, technology is now advanced enough that there are photographs of atoms. You can google "image of atoms" to find the pictures. But early investigation of atoms involved things like bombarding them with subatomic particles and measuring the scattering and reflecting patterns.