step backward for uncertainty

Reuters reports that six Italian earthquake scientists have been jailed for manslaughter for "failing to give adequate warning of the 2009 earthquake in the city of L'Aquila."

Prediction of events with some component of randomness is necessarily uncertain—to think otherwise is to misunderstand the whole endeavor. The fault here is not with the scientists, for predicting incorrectly, but with the public for believing this prediction came with certainty. To suppress predictors of random events for predicting incorrectly is to court ignorance and block progress, as it discourages the very research which will one day improve our ability to predict such events.

playing cards

Cards are 52 rectangles of stiff paper, or cardstock decorated uniformly (to ensure indistinguishability) on one side, on the other, divided into four "suits" of thirteen cards each, numbered from two to ten, plus a jack, a queen, a king, and an ace.

Cards are randomized via a physical process called "shuffling," which can be realized via a number of techniques. Proper randomness is achieved by seven "shuffles."

Although a number of different games involving any number of players and cards (e.g. poker, "go fish") are possible, there is a long tradition of four player games, where each is dealt thirteen cards (i.e. a quarter of the deck). Usually, one suit is declared "trump" (i.e. it dominates cards of any other suit, no matter their value), and play proceeds as players lay down cards sequentially. Every four cards constitute a "trick" which one player wins and keeps for himself. Games in this tradition include whist, bridge, spades, and hearts.

I appear to be a member of the last generation for which the above is common knowledge. Casual questioning of average samples of those not ten years my junior reveals (i) the general assumption that card games are simply a subset of computer games, (ii) uncertain knowledge about the constitution of a deck, and (iii) a vanishingly small understanding of appropriate randomization procedures.

"random" and "determinate"

Do not be fooled by the dichotomy "random" vs. "law-governed." Randomness is not a property of events, it is not correlated with a particular type of cause or lack thereof. Randomness is a property of data. Consider three bodies moving in accordance with the laws of Newtonian gravity, with no additional forces acting upon them. Suppose two are rotating mutually in a plane while the third crosses this plane (between the other two) repeatedly in the course of its movement. Now, examine the system at suitably coarse, but regular intervals, marking a 1 in one's logbook if the third body is on this side of the other two and a 0 in one's logbook if it is on that side. The sequence of 0's and 1's you are left with is data about the system. As it turns out, this sequence of 0's and 1's will be indistinguishable from one which has been generated by tossing a "fair coin." In other words, there will be no discernible pattern in the data, in this sense it is random. Yet the three body system is completely determinate, every development is predictable with an arbitrary degree of precision given a precise enough knowledge of the initial conditions. Suppose one stumbles across such a system in nature, and observes it for many many years, generating a long string of data. No amount of knowledge of the laws which govern the system can allow one to precisely predict the next piece of data. This is because there exists an infinite number of solutions to the problem posed by the data one has collected, each corresponding to a different set of initial conditions and, mutatis mutandis, to a different subsequent development of the three-body system. We call a complex system with this characteristic chaotic. Most natural systems are chaotic in this sense.