ABSTRACT
The m ost obvious problem facing the would-be reader of twentieth-century science publications is the vast amount of material to be covered as compared with earlier centuries. The main cause of this is the rapid increase in the number of scientists producing research round the world. Consider this first in terms of world population. In the seventeenth century, population growth was slow. The number of people in existence world-wide in the middle of the seventeenth century w as perhaps about double what it was at the beginning of the Christian era. Since that time, and especially in the twentieth century, populations have grown much more rapidly. In 1950, the worldwide population was double what it had been in 1900. From this cause alone, a pro rata growth in number of scientists might be expected. But this is only part of the story. Educational standards have also improved rapidly worldwide over the past century (though obviously more rapidly in some countries than in others). For example, in the first half of the twentieth century, the number of people entering higher educa tion in the USA doubled every 15 years: much more quickly than population growth. (The rate of increase in the UK was only slightly slower.) Taking this a stage further, it might be expected that the research-active population would be better measured in terms of doctorates awarded, rather than first degrees only. After the Second World War, interest in doctoral studies rose more rapidly in some countries even than growth in higher-education numbers as a whole. In the USA, for example, the number of doctoral students doubled between the
beginning and end of the 1960s. These rates of increase are a good deal shorter than the average lifetime of a scientist. It can be estimated that the number of qualified scientists who are alive today is more than the total number who are dead. Perhaps three-quarters of all the scientific researchers who have ever existed are around now.
