Posted by Gopal Unnikrishna
The Half-Life of Facts : How Knowledge Changes
Scientometrics: The Science of Science
In early Astronomy there were nine planets in the solar system. None were known to exist outside it. Since then, astronomers have spotted over 800 planets around other stars and demoted Pluto to a mere "dwarf planet". Even a cursory glance at other fields of science reveals similar patterns.
Samuel Arbesman, a mathematician at Harvard, calls this "The Half-life of Facts", He explains that this churn of knowledge is like radioactive decay: you cannot predict which individual fact is going to succumb to it, but you can know how long it takes for half the facts in a discipline to become obsolete. Such quantitative analysis of science has become known as scientometrics.
Put simply, scientometrics is the science of science. It grew out of bibliometrics, the science of books and research papers. In bibliometrics the unit of measurement is a research paper. Librarians were some of the first people to do this They had to grapple with the question what to carry on their shelves. They had to calculate which fields get overturned really rapidly, in other words, which papers and books people were unlikely to care about in the future.
But bibliometrics is only one sub field of scientometrics. There are all kinds of ways that you can quantify science: you can measure the number of discoveries that are occurring within a particular field, the number of elements in the periodic table, etc. Broadly, scientometrics is about quantifying and understanding how science occurs. That includes both the social aspects of science and the relationship between science and technology. It is about how the facts of the world—the stuff we know—grow in number, and how they change.
In saying that a fact has a half-life, one is trying to illustrate how knowledge changes and this is best done by making an analogy to radioactivity. When you have a big chunk of uranium, you can graph out the decay; you can say it takes 4.47 billion years for half of the atoms in a chunk of uranium to break down. You aren't going to know which half, but you know the overall rate of the decay. And the same thing is true for science, and for knowledge in general. For example, in the area of medical science dealing with hepatitis and cirrhosis, two liver diseases, researchers actually measured how long it takes for half of the knowledge in these fields to be overturned. What they found is that there is a nice, smooth rate of decay; you can predict: that every 45 years, half of this particular sort of knowledge gets outdated.
What scientific fields decay the slowest—or the fastest—and what drives that difference?Well it depends. Medicine still has a very short half-life; in fact it is one of the areas where knowledge changes the fastest. One of the slowest is mathematics, because when you prove something in mathematics it is pretty much a settled matter unless someone finds an error in one of your proofs. Social sciences have a much faster rate of decay than the physical sciences,
The whole concept calls attention to the human habit of becoming accustomed to whatever state of affairs is true when a situation is initially examined. By showing how knowledge about the world shifts systematically, you seem to be suggesting a renewed vigilance against growing complacency about knowledge of the world.
It shows people how knowledge changes. But at the same time It wants to say, now that you know how knowledge changes, you have to be on guard, so you are not shocked when your children coming home to tell you that dinosaurs have feathers.
Source
The Half-Life of Facts : How Knowledge Changes
Scientometrics: The Science of Science
In early Astronomy there were nine planets in the solar system. None were known to exist outside it. Since then, astronomers have spotted over 800 planets around other stars and demoted Pluto to a mere "dwarf planet". Even a cursory glance at other fields of science reveals similar patterns.
Samuel Arbesman, a mathematician at Harvard, calls this "The Half-life of Facts", He explains that this churn of knowledge is like radioactive decay: you cannot predict which individual fact is going to succumb to it, but you can know how long it takes for half the facts in a discipline to become obsolete. Such quantitative analysis of science has become known as scientometrics.
Put simply, scientometrics is the science of science. It grew out of bibliometrics, the science of books and research papers. In bibliometrics the unit of measurement is a research paper. Librarians were some of the first people to do this They had to grapple with the question what to carry on their shelves. They had to calculate which fields get overturned really rapidly, in other words, which papers and books people were unlikely to care about in the future.
But bibliometrics is only one sub field of scientometrics. There are all kinds of ways that you can quantify science: you can measure the number of discoveries that are occurring within a particular field, the number of elements in the periodic table, etc. Broadly, scientometrics is about quantifying and understanding how science occurs. That includes both the social aspects of science and the relationship between science and technology. It is about how the facts of the world—the stuff we know—grow in number, and how they change.
In saying that a fact has a half-life, one is trying to illustrate how knowledge changes and this is best done by making an analogy to radioactivity. When you have a big chunk of uranium, you can graph out the decay; you can say it takes 4.47 billion years for half of the atoms in a chunk of uranium to break down. You aren't going to know which half, but you know the overall rate of the decay. And the same thing is true for science, and for knowledge in general. For example, in the area of medical science dealing with hepatitis and cirrhosis, two liver diseases, researchers actually measured how long it takes for half of the knowledge in these fields to be overturned. What they found is that there is a nice, smooth rate of decay; you can predict: that every 45 years, half of this particular sort of knowledge gets outdated.
What scientific fields decay the slowest—or the fastest—and what drives that difference?Well it depends. Medicine still has a very short half-life; in fact it is one of the areas where knowledge changes the fastest. One of the slowest is mathematics, because when you prove something in mathematics it is pretty much a settled matter unless someone finds an error in one of your proofs. Social sciences have a much faster rate of decay than the physical sciences,
The whole concept calls attention to the human habit of becoming accustomed to whatever state of affairs is true when a situation is initially examined. By showing how knowledge about the world shifts systematically, you seem to be suggesting a renewed vigilance against growing complacency about knowledge of the world.
It shows people how knowledge changes. But at the same time It wants to say, now that you know how knowledge changes, you have to be on guard, so you are not shocked when your children coming home to tell you that dinosaurs have feathers.
Source
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