Letters from the November 17, 2007, issue of Science News

Unequal opportunity

“The Wealth of Nations” (SN: 9/1/07, p. 138) describes the difficulty of moving from exporting one product to exporting another in terms of a “distance” between various products. I would imagine, however, that a nation that already manufactures computers, for example, could easily move into calculators, but that the reverse might not be true.