Doing weights

This popular science article reveals CSIRO’s role in re-defining the kilogram and covers the role in which  Australia is playing a large part - that is in creating perfect spheres from a single crystal of extremely pure silicon. 

The kilogram is one of seven base units in the International System (SI) used in science, commerce and everyday life.

It is currently the only one still defined by a physical object – a lump of metal kept in a vault in France.

All the others have moved with the scientific times and are defined in terms of a fundamental constant of nature so anyone anywhere can work them out.

CSIRO's work in creating precision optical components for applications such as astronomy and photonics, has meant that CSIRO is able to contribute the necessary cutting, grinding, polishing and measurement skills to make the spheres perfect.

This article has sub-headings:

• weighing in
• round and round
• are we there yet?
• measuring up.

This article also contains several pull-out boxes headed:

• the seven base SI units
• Avogadro – the atom man
• how things change.

Watch The story of the spheres (Video).

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• CSIRO Materials Science and Engineering
• Australian Centre for Precision Optics
• The Avogadro Project [external link]
• The international system of units [external link]
• Precision spheres in push to re-define kilogram
• The story of the spheres (Video)