Magazine
Latest Issue

News & curiosities

By prospect   March 2005

The ever-shrinking kiloThe kilogram is losing weight. Despite the fact that it never leaves a secure safe in Paris, the 90 per cent platinum and 10 per cent iridium cylinder created in 1889 as the standard definition of a kilogram has lost around 50 micrograms since being cast. No one knows why, but more importantly, no one can come up with a better way of defining the kilo, the only one of physics’s seven base units to be defined in reference to a material artefact rather than a fundamental constant (like the speed of light, used to define the second).…

Register today to continue reading

You’ve hit your limit of three articles in the last 30 days. To get seven more, simply enter your email address below.

You’ll also receive our free e-book Prospect’s Top Thinkers 2020 and our newsletter with the best new writing on politics, economics, literature and the arts.

Prospect may process your personal information for our legitimate business purposes, to provide you with newsletters, subscription offers and other relevant information.

Click here to learn more about these purposes and how we use your data. You will be able to opt-out of further contact on the next page and in all our communications.

We want to hear what you think about this article. Submit a letter to letters@prospect-magazine.co.uk

More From Prospect