A memorial algorithm

Scientific American reveals the moving mathematics behind the layout of the 9/11 memorial:

The planners of the memorial, which will be dedicated this weekend where the Twin Towers once stood, solicited requests from victims’ loved ones for “meaningful adjacencies”—names that should appear together on the memorial. Roughly 1,200 responses came back, asking that a victim’s name be grouped with specific colleagues, with family members or with friends who also perished in the attacks.

The names algorithm works in two stages. The first stage, really an algorithm unto itself, builds clusters of names from the adjacency requests. If person A needs to be near person B, and person B near person C, those three names will form a cluster. “That kind of results in a pile of really irregularly shaped puzzle pieces,” [software artist Jer] Thorp says. Among the various indivisible bunches formed by the clustering algorithm were blocks with as many as 70-odd names.

A second, space-filling algorithm takes those puzzle pieces and fits them into place within the confines of the 76 bronze panels enclosing each memorial pool.

In its overarching structure, the arrangement of names preserves the order behind the victims’ lives—their work, their friends, their families. “You have this enormously organic, complex, human web of meaning,” [Jake Barton, principal of Local Projects,] says. At the same time, the seeming disorder in the arrangement of victims’ names preserves the chaos and randomness behind their deaths.

[Thanks to Camilla Mortensen for pointing this out.]