The Half-Life of Facts Read Free Page B

decades. Lehman looked at each of these areas over hundreds of years. He examined philosophy over the six hundred years from 1275 to 1875, botany over the three hundred years from 1600 to 1900, and geology over the four hundred years from 1500 to 1900.
    Each area was found to have a characteristic rate of increase. Here are doubling times (the number of years it takes for the yearly contributions in these fields to double) from Lehman’s findings, along with a few more recent areas examined:
    Field
Doubling Time (in years)
Medicine and hygiene
87
Philosophy
77
Mathematics
63
Geology
46
Entomology
39
Chemistry
35
Genetics
32
Grand opera
20
    Independently, a number of thinkers were coming to the realization that the growth of knowledge was subject to patterns, and was far from random. Similarly, different types of growth fit different types of knowledge creation. For example, opera is a far faster-changing domain than the sciences. Even though science and opera composition are inherently creative, science is limited by what we can determine about nature. Science can develop only as quickly aswe can figure out things about the world. Grand opera, however, is not limited by what is true, only by what is beautiful, and should therefore be able to grow more rapidly, since it doesn’t have to be rigorously subjected to experimentation.
    In addition, we can see a hint of how more fundamental discoveries grow by comparing them to ones that are more dependent on other areas, which build on work done in other fields. For example, genetics and chemistry, two areas of the basic sciences, proceed at similar rates. On the other hand, medicine and hygiene are much slower, and are also areas that rely on these more basic fields for new discoveries. Perhaps this is a hint that more derivative fields move more slowly compared to the more basic areas of knowledge on which they depend.
    Price’s and Lehman’s efforts showed that looking at how knowledge grows in a systematic way was finally possible, and they unleashed a wave of discoveries.
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    PRICE’S approach, looking at how science progresses by examining scientific articles and their properties, has proven to be the most successful and fastest-growing area of scientometrics. While scientific progress isn’t necessarily correlated with a single publication—some papers might have multiple discoveries, and others might simply be confirming something we already know—it is often a good unit of study.
    Focusing on the scientific paper gives us many pieces of data to measure and study. We can look at the title and text and, using sophisticated algorithms from computational linguistics or text mining, determine the subject area. We can look at the authors themselves and create a web illustrating the interactions between scientists who write papers together. We can examine the affiliations of each of the authors and try to see which collaborations between individuals at different institutions are more effective. And we can comb through the papers’ citations, in order to get a sense of the research a paper is building upon.
    Examining science at the level of the publication can give us all manner of exciting results. A group of researchers at Harvard Medical School looked at tens of thousands of articles published by its scientists and mapped out the buildings on campus where they worked. Through this, they were able to look at the effect that distance has on collaboration. They found exactly what they had assumed but no one had actually measured: The closer two people are, the higher the impact of the research that results from that collaboration. They found that just being in the same building as your collaborators makes your work better.
    We can also understand the impact of papers and the results within them by measuring how many other publications cite them. The more important a work is, the more likely it is to be referenced in many other papers, implying that it has