Of all the problems in the world, scientists have come close to solving one that probably never occurred to most of us: how to create a perfect sphere.

Which prompts the question: Why do we need one?

It seems a perfect sphere is needed to determine the exact weight of the kilogram. The fact that scientists have created the "roundest objects in the world" is hot news to measurement gurus in Paris, where a 120-year-old "lump" of iridium and platinum sits in a vault.

According to an article in New Scientist, "The kilogram is the only remaining standard of measurement tied to a single object" — and that single object is the lump in Paris.

 

The problem is, the mass of the lump has been changing relative to the 40-some copies of it in other countries, so a race is on by metrologists (researchers whose speciality is policing units and measures) to come up with a new definition of the kilogram by 2011.

One of the suggestions is to define it in terms of silicon atoms, which is where the perfect spheres come in. A team called the Avogadro Project says it is using silicon to create the spheres because silicon has a well-known crystal structure, is stable and is relatively easy to use.

A kind of slide presentation of the project’s creation of perfect spheres can be seen here.