TLDR: Why Half Your Skills Expire Every Few Years
Date: 2026-02-08 Source: https://arpitbhayani.me/blogs/half-life
Overview
That is the half-life of knowledge in computer science and software engineering - the time it takes for half of what you know to be replaced by better tools, approaches, or understanding. For an engineering degree earned in 1930, the half-life was roughly 35 years. By 1960, it had dropped to about a decade.
Key Points
- Every three years, half of what you know becomes obsolete.
- The Half-Life: The half-life of knowledge borrows its name from nuclear physics, where it describes how long it takes for half of an unstable substance to decay.
- Why Software Ages Faster: Not all engineering knowledge decays equally.
- Two Layers of Software Knowledge: Software expertise exists in two distinct layers.
- Experience vs Freshness: The shrinking half-life helps explain a persistent industry dynamic: experience does not age linearly in software.