In principle, barring the intervention of chance, identical causes lead to identical effects. And except in chaotic systems, similar causes lead to similar effects. Borges’ story “Pierre Menard” exemplifies an extreme version of this idea: an early 20’th century writer studies Cervantes’ life and times so thoroughly that he is able to recreate several chapters of “Don Quixote” without mistakes and without consulting the original.
Meanwhile, back at the ShopRite parking lot in Croton on Hudson, NY, they’d installed half a dozen identical red and white parking signs, presumably all from the same print run, and all posted in similar environments, except for two in a sunnier location.
The irregular patterns of cracks that formed as the signs weathered were so similar that at first I thought the cracks had also been printed, but then I noticed small differences. The sharp corners on letters like S and E, apparently points of high stress, usually triggered near-identical cracks in each sign, but not always, and in the sunnier signs many additional fine cracks formed.
Another example of reproducibly irregular dynamics was provided over 30 years ago by Ahlers and Walden’s experiments on convective turbulence, where a container of normal liquid helium, heated from below, exhibited nearly the same sequence of temperature fluctuations in several runs of the experiment.