Editor's note

The official definition of a metre in 1793 was one ten-millionth of the distance from the equator to the North Pole. Then it was a physical rod kept in the French Academy of Sciences. By 1983 the metre was set as the distance light travels in a vacuum over a fraction of a second.

All the other physical measures underpinning the metric system have slowly been replaced with similar calculations against physical constants of the universe – except the kilo. For 129 years, the prototypical kilo was a single block of platinum and iridium in France.

That block, however, has slowly been losing mass, and for two decades the international scientific community has looked for a solution. Now, Kevin Pimbblet explains, they have gathered in France to vote for a new definition.

Madeleine De Gabriele

Deputy Editor: Energy + Environment

Stefan Rotter/Shutterstock

The kilogram is being redefined – a physicist explains

Kevin Pimbblet, University of Hull

The international prototype kilogram keeps changing weight so scientists have come up with a new way to calculate.

A vaccine that could block mosquitoes from transmitting malaria

Wei-Chiao Huang, University at Buffalo, The State University of New York; Jonathan Lovell, University at Buffalo, The State University of New York

Researchers have tried unsuccessfully for decades to develop a malaria vaccine. Now a new approach, showing promise in mice, suggests it is possible to block mosquitoes from spreading the disease.

How the use of emoji on Islamophobic Facebook pages amplifies racism

Ariadna Matamoros-Fernández, Queensland University of Technology

Emoji can be used on social media to spread racism in ways that make it seem normal, mundane and acceptable.

Muckracking journalists who shaped southern Africa over three centuries

Anton Harber, University of the Witwatersrand

A new book celebrates the long and rich history of investigative reporting in southern Africa, and highlights some hidden and forgotten gems.

Education does not always equal social mobility

Louis Volante, Brock University; John Jerrim, UCL

Conventional wisdom across much of the Western world says there's a strong link between education and upward social mobility. Really?

Arts + Culture

  • For the sake of kids, embrace math

    Andy Hargreaves, Boston College; Pasi Sahlberg, UNSW

    Instead of getting "back to basics" to improve math skills, we should make math literacy a priority by developing, attracting and supporting skilled teachers, and improving math literacy at home.

Environment + Energy