Diffusion View

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Science  28 May 2004:
Vol. 304, Issue 5675, pp. 1239
DOI: 10.1126/science.304.5675.1239d
CREDIT: M. GASTNER AND M. NEWMAN, PNAS 101, 20 (2004)

Physicists at the University of Michigan say they have harnessed a principle from physics to solve the problem of how to present maps that show geographic regions in proportion to their population. “Previous methods didn't produce very good maps,” says Mark Newman, co-author of a paper on the new method in the 18 May issue of the Proceedings of the National Academy of Sciences. The distortion was so great that you couldn't recognize geographic areas, and sometimes areas were forced to overlap, he says. But “we found a way of actually producing these maps [using] the idea of diffusion of gases.” Just as a gas spreads to fill available space with uniform density, the computer model by Newman and Michael T. Gastner spreads out population to a uniform distribution and stretches or shrinks state boundaries accordingly.

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