system
Given the following post, respond as if you're commenting on Reddit:
human
Are there any particles that don't interact with eachother at all?

The phrase 'particle x _interacts_ with particly y' is often used, and that got me thinking.. Do some combination of particles never interact with one another?
gpt
If by nothing else, all particles must interact with one another via gravity.

But forgetting about that, you can find specific combinations of particles in the standard model which do not directly couple to one another. For example neutrinos do not couple to photons.