LITMIR.BIZ

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an extremely elaborate set of conventions, in practice one straightforward principle determines which ships give way to which: the “Law of Gross Tonnage.” Quite simply, the smaller ship gets out of the way of the larger one. Some animals are also lucky enough to have such clear-cut dominance hierarchies. As Neumann observes, “Look at fish, for example: the bigger one is the dominant one. It’s very simple.” And because it’s so simple, it’s peaceful. Unlike chickens and primates, fish make order without shedding blood.

      When we think about the factors that make large-scale human societies possible, it’s easy to focus on technologies: agriculture, metals, machinery. But the cultural practice of measuring status with quantifiable metrics might be just as important. Money, of course, need not be the criterion; a rule like “respect your elders,” for instance, likewise settles questions of people’s status by reference to a common quantity. And the same principle is at work between nations as within them. It is often noted that a benchmark like national GDP—which underlies the invite lists to diplomatic summits such as the G20—is a crude, imperfect measurement. But the existence of any benchmark at all transforms the question of national status from one demanding at least a linearithmic number of tussles and resolutions into something with a single reference point that ranks all. Given that nation-to-nation status disputes often take military form, this saves not only time but lives.

      Linearithmic numbers of fights might work fine for small-scale groups; they do in nature. But in a world where status is established through pairwise comparisons—whether they involve exchanging rhetoric or gunfire—the amount of confrontation quickly spirals out of control as society grows. Operating at industrial scale, with many thousands or millions of individuals sharing the same space, requires a leap beyond. A leap from ordinal to cardinal.

      Much as we bemoan the daily rat race, the fact that it’s a race rather than a fight is a key part of what sets us apart from the monkeys, the chickens—and, for that matter, the rats.

*This is far from Bradáč’s only record—he can escape from three pairs of handcuffs while underwater in roughly the same amount of time.

*Actually, the average running time for Bubble Sort isn’t any better, as books will, on average, be n/2 positions away from where they’re supposed to end up. A computer scientist will still round n/2 passes of n books up to O(n2).

*On rare occasions, as in boxing—where it is medically unsafe for a boxer to fight again after being recently knocked out—two bronzes are awarded instead.

*It’s interesting to note that NCAA’s March Madness tournament is consciously designed to mitigate this flaw in its algorithm. The biggest problem in Single Elimination, as we’ve said, would seem to be a scenario where the first team that gets eliminated by the winning team is actually the second-best team overall, yet lands in the (unsorted) bottom half. The NCAA works around this by seeding the teams, so that top-ranked teams cannot meet each other in the early rounds. The seeding process appears to be reliable at least in the most extreme case, as a sixteenth-seeded team has never defeated a first seed in the history of March Madness.

       4 Caching

       Forget About It

      In the practical use of our intellect, forgetting is as important a function as remembering.

      —WILLIAM JAMES

      You have a problem. Your closet is overflowing, spilling shoes, shirts, and underwear onto the floor. You think, “It’s time to get organized.” Now you have two problems.

      Specifically, you first need to decide what to keep, and second, how to arrange it. Fortunately, there is a small industry of people who think about these twin problems for a living, and they are more than happy to offer their advice.

      On what to keep, Martha Stewart says to ask yourself a few questions: “How long have I had it? Does it still function? Is it a duplicate of something I already own? When was the last time I wore it or used it?” On how to organize what you keep, she recommends “grouping like things together,” and her fellow experts agree. Francine Jay, in The Joy of Less, stipulates, “Hang all your skirts together, pants together, dresses together, and coats together.” Andrew Mellen, who bills himself as “The Most Organized Man in America,” dictates, “Items will be sorted by type—all slacks together, shirts together, coats, etc. Within each type, they’re further sorted by color and style—long-sleeved or short-sleeved, by neckline, etc.” Other than the sorting problem this could entail, it looks like good advice; it certainly seems unanimous.

      Except that there is another, larger industry of professionals who also think obsessively about storage—and they have their own ideas.

      Your closet presents much the same challenge that a computer faces when managing its memory: space is limited, and the goal is to save both money and time. For as long as there have been computers, computer scientists have grappled with the dual problems of what to keep and how to arrange it. The results of these decades of effort reveal that in her four-sentence advice about what to toss, Martha Stewart actually makes several different, and not fully compatible, recommendations—one of which is much more critical than the others.

      The computer science of memory management also reveals exactly how your closet (and your office) ought to be arranged. At first glance, computers appear to follow Martha Stewart’s maxim of “grouping like things together.” Operating systems encourage us to put our files into folders, like with like, forming hierarchies that branch as their contents become ever more specific. But just as the tidiness of a scholar’s desk may hide the messiness of their mind, so does the apparent tidiness of a computer’s file system obscure the highly engineered chaos of how data is actually being stored underneath the nested-folder veneer.

      What’s really happening is called caching.

      Caching plays a critical role in the architecture of memory, and it underlies everything from the layout of processor chips at the millimeter scale to the geography of the global Internet. It offers a new perspective on all the various storage systems and memory banks of human life—not only our machines, but also our closets, our offices, our libraries. And our heads.

      The Memory Hierarchy

      A certain woman had a very sharp consciousness but almost no memory.… She remembered enough to work, and she worked hard.

      —LYDIA DAVIS

      Starting roughly around 2008, anyone in the market for a new computer has encountered a particular conundrum when choosing their storage option. They must make a tradeoff between size and speed. The computer industry is currently in transition from hard disk drives to solid-state drives; at the same price point, a hard disk will offer dramatically greater capacity, but a solid-state drive will offer dramatically better performance—as most consumers now know, or soon discover when they begin to shop.

      What casual consumers may not know is that this exact tradeoff is being made within the machine itself at a number of scales—to the point that it’s considered one of the fundamental principles of computing.

      In 1946, Arthur Burks, Herman Goldstine, and John von Neumann, working at the Institute for Advanced Study in Princeton, laid out a design proposal for what they called an electrical “memory organ.” In an ideal world, they wrote, the machine would of course have limitless quantities of lightning-fast storage, but in practice this wasn’t possible. (It still isn’t.) Instead, the trio proposed what they believed to be the next best thing: “a hierarchy of memories, each of which has greater capacity than the preceding but which is less quickly accessible.” By having effectively a pyramid of different forms of memory—a small, fast memory and a large, slow one—maybe we could somehow get the

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