Just the Mesofacts, Ma’am

Samuel Arbesman defines the area between facts that are permanent and those that change rapidly:

When people think of knowledge, they generally think of two sorts of facts: facts that don’t change, like the height of Mount Everest or the capital of the United States, and facts that fluctuate constantly, like the temperature or the stock market close.

But in between there is a third kind: facts that change slowly. These are facts which we tend to view as fixed, but which shift over the course of a lifetime. For example: What is Earth’s population? I remember learning 6 billion, and some of you might even have learned 5 billion. Well, it turns out it’s about 6.8 billion.

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These slow-changing facts are what I term “mesofacts.” Mesofacts are the facts that change neither too quickly nor too slowly, that lie in this difficult-to-comprehend middle, or meso-, scale. Often, we learn these in school when young and hold onto them, even after they change. For example, if, as a baby boomer, you learned high school chemistry in 1970, and then, as we all are apt to do, did not take care to brush up on your chemistry periodically, you would not realize that there are 12 new elements in the Periodic Table. Over a tenth of the elements have been discovered since you graduated high school! While this might not affect your daily life, it is astonishing and a bit humbling.

Arbesman also has a website and blog focusing on mesofacts. For example: The percentage of people in the world who used mobile phones in 1997 was was 4 percent; by 2007, it was nearly 50 percent.

What is your favorite slow-changing fact?