Not Exactly An Expiration Date On All Facts

Review of book The Half Life Of Facts-How-Everything-We-Know-Has-An-Expiration-Date by Samuel Arbesman, Current, Penguin Group 2012-13. This review also appeared in

When protons themselves, particles that characterize elements, have half-lives, it should not be shocking that knowledge is not forever. The proton’s half-life, however, is on the order of 1033 to 1034 years. Other radioactive processes, such as beta decay, operate on a much more imaginable time scale, and it’s the latter variety that forms the basis of Arbesman’s metaphor. In the same way that we cannot predict which individual nuclei will decay, we don’t know which facts from our everyday world will soon become obsolete. But on the whole, it seems that half will decay during an observable time scale.

The “facts” of science are not immune to this decay process, and as the author points out, this is to be expected from the nature of science, which deals with models of reality, not absolutes. These models are constantly refined and occasionally overturned as a combination of new technology and human insight surface. Other factors that alter the landscape of facts include the sheer number of scientists at work today (80% of the total who have ever lived); experiments that are often published without being verified by neutral parties; and fields of investigation such as nutrition and cancer research, which involve many uncontrollable variables.

As much as I enjoyed the book, I wish Arbesman had spent more energy investigating different half-lives of knowledge in various subjects. The author does cite research by Rong Tang, who investigated the half-lives of scholarly books. The half-lives range from 13.07 to 7.15 years for subjects ranging from physics to psychology, respectively. How Tang manages three to four significant figures is suspect, but, more importantly, the reader is left wondering why the books became outdated. Is it high standards — if 10% of the content is no longer factual, a new book must surface? Or is it because the books are centered around cutting edge research, which deal with many hypotheses that are still being tested?

One interesting chemistry-related example explored by Arbesman involves the 1904 Nobel Prize in Chemistry, awarded to Sir William Ramsay for the discovery of four gases. These gases were labeled as inert. About six decades later, chemists managed to get three of the four to react, but only by using powerful electron muggers. So over the last century has the idea of “inert gases” become an obsolete fact? It is not completely thrown out when all noble gases are still known to be inflammable and incapable of reacting with any of the alkali metals, the most reactive of the elements. More importantly in my view, Ramsay’s work — although rarely cited in current research and which could be used as “evidence” for decayed knowledge — remains an intellectual gem. His original paper is an excellent example of careful scientific thought. Using experimental evidence, Ramsay thoroughly considered alternative explanations for the nitrogen-density disparities that led to the discovery of argon. But that kind of thought process did not make media headlines at the turn of the century, nor does it now. Instead, the superficial facts or often premature research claims sell better. As a result, they can also, unfortunately, distort our sense of the half-life of knowledge.

What also remains unexplored is how the half-lives of different aspects of factual knowledge vary in a given field, such as chemistry. The number of elements in the periodic table and the decimal places of atomic masses are constantly mutable, but sodium’s reaction in water will still be violent four thousand years from now.

In chemical education, while providing students with a foundation of central concepts, we point out that certain basics have not changed for a while. At the same time, we cannot create the illusion that all will remain unshaken. It’s not long ago that the relative inertness of gold, the poisonous characteristics of thallium and liquid nature of mercury were all explained by considering Einstein’s relativistic effects of certain large nuclei on s orbitals. A decade ago, while listing the halogens, it was a good idea to place a “to be discovered” square under astatine. Now it’s been filled with 117Uus. That in itself isn’t earth-shattering news. The addition of new elements is akin to Arbesman’s example of extrasolar planets. Such a list grows monthly. But the more interesting storyline is the hope of finding life elsewhere. Similarly, in chemistry, with relation to the synthesis of large nuclei, the exciting possibility is that a new island of stability is lurking somewhere high among the atomic numbers.


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