The Half-Life of Notes: Why Your Second Brain Decays and What to Do About It
Most second brains are built with ambition and abandoned with silence.
The pattern is familiar. You discover a note-taking system — Obsidian, Notion, Logseq, a folder of Markdown files. You read about Zettelkasten, PARA, or evergreen notes. You capture diligently for weeks or months. The system fills up. It feels productive.
Then, somewhere around month six, you notice something. You open a note from three months ago and realize you no longer know what it means. The context has evaporated. The source link is dead. The half-formed thought it captured is no longer half-formed — it is just dead.
The system did not fail because you stopped adding to it. It failed because notes have a half-life, and most knowledge systems are designed for accumulation, not maintenance.
This essay is about knowledge entropy — the quiet forces that cause personal knowledge systems to lose value over time — and the deliberate practices that keep a system alive across years, not months.