DOES PHYSICS LITERATURE OBSOLESCE? A STUDY OF VARIATION OF CITATION FREQUENCY WITH TIME FOR INDIVIDUAL JOURNAL ARTICLES IN PHYSICS

It is of potential interest for a number of reasons to study the way the use made of scientific literature changes over time, and in particular whether its use declines and if so how fast. There is a large literature on ‘obsolescence’, much of which is characterised by imprecise definition, inadequate data, unsatisfactory analysis and invalid conclusions. Most studies are synchronous, that is, they give date distributions of uses or citations at one period of time; the pattern of use of any given item cannot be determined from such analyses unless allowance is made for the different size of the literature at different dates. It is difficult to allow for literature growth with any precision, and a much more reliable method of determining the pattern of use is to take past articles and study how many citations have been made to them in successive years, ie to conduct a diachronous study.