The speed at which individuals, information and ideas can spread has greatly increased in the past several hundred years. And, unsurprisingly, it has done so according to mathematical rules. The upper limit of travel distances made by people in France in a single day has exponentially increased over a 200-year period, for example, mirroring Bradley’s anecdotal evidence. Similar trends hold for air and sea transportation. The curves for sea transport begin a bit earlier (around 1750), and air transit of course starts later (from the 1920s onwards), but like movement over land, these other modes of transportation obey clear mathematical regularities.
These transportation speeds have clear implications for how the world around us changes. For instance, Cesare Marchetti, an Italian physicist and systems analyst, examined the city of Berlin in great detail and showed that the city has grown in tandem with technological developments. From its early dimensions, when it was hemmed in by the limits of pedestrians and coaches, to later times, when its size ballooned alongside the electric trams and subways, Berlin’s general shape was dictated by the development of ever more powerful technologies.
Marchetti showed that Berlin’s expanse grew according to a simple rule of thumb: the distance reachable by current technologies in thirty minutes or less. As travel speeds increased, so too did the distance traversable and the size of the city.
So we arrive at the foundations of a variety of ever-changing facts based on the development of travel technologies: the natural size of a city; how long information takes to wing its way around the world; and how distant a commute a reasonable person might be expected to endure. And from communication and urban growth to information processing and medical developments, the facts of our everyday lives are governed by technological progress.
While the details of each technological development might be unknown – what I can download, or how many more transistors can be crammed into a square inch, for instance – there are mathematically defined, predictable regularities to how these changes occur. All of these facts, ever changing, are subject to the rules of technological change. And more often than not these ultimately follow a defined pattern: their own mini-Moore’s Law.
This is an edited extract from The Half-Life Of Facts: Why Everything We Know Has An Expiration Date, by Samuel Arbesman. If you would like to comment on this article or anything else you have seen on Future, head over to our Facebook page or message us on Twitter.