Book Review: The Half-Life of Facts; why everything we know has an expiration date

Review by Evan Gough

Knowledge is changing all the time. New facts replace old facts, more precise measurements supersede previous measurements. What was once considered true is overturned daily in our quickly changing times. In “The Half-Life of Facts: why everything we know has an expiration date,” Samuel Arbesman brings some clarity to our constantly changing factual landscape.

It turns out that facts have a shelf-life, and that there is a mathematical predictability to that shelf-life. With an engaging style of storytelling, and just the right amount of graphs and tables, Arbesman walks us through the field of scientometrics, the scientific study of science itself. What do we learn?

We learn that scientific studies themselves have half-lives. For example, the half-life of a study on hepatitis and cirrhosis, both liver diseases, is about 45 years. After 45 years, half of that knowledge will be overturned or superseded. We also learn that differing sciences have different half-lives. The half-life of a physics paper is on average 13.07 years, in Math it’s 9.17 years, and in Psychology it’s 7.15.

“The Half-Life of Facts” is full of familiar examples of, and insights into, our changing knowledge. Universe Today readers will be familiar with the demotion of Pluto from planet to trans-Neptunian object. Other examples in Arbesman’s book will be unfamiliar. For instance, it may be surprising to find out that for many decades it was an established fact that humans had 48 chromosomes. (We have 46.) This was considered such an elementary truth, that other researchers who counted 46 sometimes shut down their research prematurely, thinking they were somehow in error. Eventually, however, the truth did win out.

How science gets us closer to the truth over time is the main thrust of this book. That, and the predictability of that progress towards greater accuracy. But there are chapters that cover how facts spread, how new knowledge is hidden in connections between previously published studies, and how improvements in technology can spur science on to more accurate truths.

Overall, “The Half-Life of Facts” is an engaging book. It moves along at a nice pace, and I think Universe Today readers will find it very interesting. My only beef with the book is its title. It’s about much more than the half-life of facts. It’s a vivid account of the surprising ways in which new facts are accumulated, and how old knowledge is overturned.

Find out more about this book and the author at this website.

11 Replies to “Book Review: The Half-Life of Facts; why everything we know has an expiration date”

  1. Ptolomeic epicycles lasted from the 3rd century BC until 1618 and beyond for some. It seems that the half life of knowledge is shrinking, possibly in the forseeable future everything we know will be overturned in a second..

  2. There are certain things which are upheld as true, but which later on are found to be only correct in some restricted domain of observation. Classical mechanics was supplanted with relativity and quantum mechanics. Classical mechanics is workable in a domain of observation that does not extend across the domain of experimental physics. However, I don’t thing many physicists would conclude that classical mechanics is false. In molecular biology the one gene to one polypeptide model is turning out to be an approximate realization, where lots of DNA is transcribed into forms of RNA that do not code for polypeptides, but which have other functions. With science we really do not work with truth, but with more of a tentative form of truth.

    This is contrasted with things which turn out to be just plain wrong, or hypotheses that at one time were working guidelines that fail. The case of Pluto is not about scientific understanding, but nomenclature. This is really nothing more than a redefinition of things.


  3. I will not buy this book as its general ideas are plainly ridiculous. Knowledge is an accumulation, like the represented bricks being the foundations of an ever rising structure on what we know. It is not the premise of various degrading of results or new answers overtime. It is also importantly based on paradigms that changes over time by the current accepted societal norms.

    It is like the oldest discovery about the stars, for example. They are not food that can be eaten. As far as I know, this factual premise hasn’t changed since sentient life first appeared on the Earth. According to this ‘theory’, what is the half-life of this fact?

    The author clearly of this book has not true concept of what science, whose contention is to falsify how science works for those who know no better. Why it is being given oxygen here is beyond me.

  4. After having read the downloadable, first chapter of Samuel Arbesman’s book, I think, the author confuses readers about his message a little bit.

    In the first chapter at one point Arbesman talks about “the amount of time for half of a subject’s knowledge to be overturned”. This is not really the same as in the rather general statement “everything we know has an expiration date”. That many of the facts I knew — we knew — decades ago have been falsified in the meantime is rather commonplace. Nothing we human beings produce — including physics and mathematics and the truth therein — will last forever (that especially mathematical truth is eternal — well, I would call it superstition).

    So, would I expect Arbesman’s book to contain something surprisingly new? Not for the expert. But it could be fun reading, if it is indeed, as the reviewer above says, “a vivid account of the surprising ways in which new facts are accumulated, and how old knowledge is overturned”, — and if you ignore this half-life-of-facts thing.

  5. This would be a good book to glean some handy info from to use whilst speaking to anti-science folks who love to moan how science is full of crap every time a theory gets revised or some slice of knowledge is updated by new measurements.

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