Solution to a weighty problem may be at hand

If you’ve been fretting about the three-decade-long effort to redefine the mass of the kilogram, there’s good news: A compromise solution may be in the works.

You didn’t know the kilogram was in doubt? As The Economist explains, some 130 years ago the kilogram was defined as the mass of a cylindrical lump of platinum-iridium alloy kept at the International Bureau of Weights and Measures near Paris. Identical lumps were created as national prototypes. Over the years, scientists have discovered minor discrepancies in the mass of the original and its copies.

Scientists, Geoff Brumfiel says in, have been looking for a way to redefine the kilogram in terms of a fundamental constant of nature, as has been done with other measurements such as the meter. The problem is, two experiments designed to create the new standard yield slightly different results.

At a conference in London last week, a former head of the bureau of weights and measures suggested a solution: Average the results of the two experiments and use that as the official standard. The idea is picking up support.

Not everyone likes the suggestion. “Deciding to just average these two results would be perfectly proper mathematics, but it would not be science,” sniffed a physicist.

If you think it doesn’t matter here, where the populace has firmly ignored efforts to introduce the metric system, don’t be so sure. The mass of a pound is based on a kilogram, so resolution of the issue could mean a few molecules more or less of salami at the deli.