Question
What is half life of knowledge?
Quick Answer
Different types of information decay at different rates. Some knowledge stays relevant for centuries. Some is obsolete by lunch. Knowing which is which changes what you pay attention to.
Half life of knowledge is a concept in personal epistemology: Different types of information decay at different rates. Some knowledge stays relevant for centuries. Some is obsolete by lunch. Knowing which is which changes what you pay attention to.
Example: A software engineer spends Monday morning reading Hacker News comments about a new JavaScript framework. By Wednesday, the thread is forgotten, the framework's hype has cooled, and nothing from that reading session changed how she works. That same week, she spends forty minutes reading the first three chapters of Fred Brooks' The Mythical Man-Month — published in 1975. Fifty years later, Brooks' observation that adding people to a late project makes it later still governs how she plans sprints. One reading session had a half-life of days. The other has a half-life of decades. Both took the same time.
This concept is part of Phase 7 (Signal vs Noise) in the How to Think curriculum, which builds the epistemic infrastructure for signal vs noise.
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- The half-life of information
Different types of information decay at different rates. Some knowledge stays relevant for centuries. Some is obsolete by lunch. Knowing which is which changes what you pay attention to.
Go beyond the answer
This topic is part of Think Clearly at Work — a guided sequence of 20 lessons.
After completing this path you will have a working capture system, protected daily focus blocks, a framework for distinguishing signal from noise, a weekly review practice, and the capacity awareness to sustain clear thinking indefinitely. These are the cognitive building blocks that make every other skill — decision-making, leadership, coaching, systems thinking — possible.
Start the path →