Half-life of knowledge

The half-life of knowledge or half-life of facts is the amount of time that has to elapse before half of the knowledge or facts in a particular area is superseded or shown to be untrue. These coined terms belong to the field of quantitative analysis of science known as scientometrics.

These ideas of half-life applied to different fields differ from the concept of half-life in physics in that there is no guarantee that the knowledge or facts in areas of study are declining exponentially. It is unclear that there is any way to establish what constitutes "knowledge" in a particular area, as opposed to mere opinion or theory.

Because scientific knowledge is growing by a factor of ten every 50 years, this means that half of what scientists may have known about a particular subject will be wrong or obsolete in 45 years.

An engineering degree went from having a half life of 35 years in ca. 1930 to about 10 years in 1960.

Donald Hebb estimated the half-life of psychology to be five years.

The concept of "half-life of knowledge" is attributed to Fritz Machlup (1962).

For example, Donald Hebb estimated the half-life of psychology to be five years.

The similar concept of a "half-life of facts" was coined by Samuel Arbesman, a Harvard mathematician and scholar at the Kaufmann Foundation.

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