alt Hacker NewsThere's: U+3000, ideographic space. It's conceptually fitting, with sentence separation being a good fit for "idea separation".
edit: well I tried to give an example, but hn seems to replace it with regular space. Here's a copy paste version: https://unicode-explorer.com/c/3000
Belying the name somewhat, I believe U+3000 is specifically meant for use with Sinoform logographs, having the size of a (fullwidth character) cell, and so it makes little sense in other contexts.