system
Given the following post, respond as if you're commenting on Reddit:
human
Which is more dense, a black hole or a proton?

A neutron? Electron? What is the most dense thing we know of?
gpt
A proton has a density of about 10^17 kg/m^3 while a stellar black hole has a density of about 10^19 kg/m^3 . However, larger black holes are less dense (because the radius increases on par with the mass), and supermassive black holes have a small density in comparison, of about a million kg/m^3 .

The electron is not known to have any finite size, but if it does, its density must be above 10^35 kg/m^3 .