Since 1889, Le Grand K, a sleek cylinder of platinum-iridium metal, was the definition of 1 kilogram of mass. Scientists made pilgrimages to it, bringing their national kilogram standards to adjust accordingly. No longer. Several dozen nations voted to redefine the kilogram and three other units of measure: the ampere, for electrical current; the kelvin, for temperature; and the mole, which describes the amount of a chemical substance. Henceforth, all seven units in the International System of Units will be defined by abstract constants of nature. “This arc of history started before the French Revolution and now, ” said physicist Stephan Schlamminger. He said the “democratization of the units” is complete.

Komodo dragons like to keep to themselves

Komodo dragons live on a handful of islands in Indonesia, but their reputation has spread far and wide. Reaching lengths of up to 10 feet, the razor-toothed monitor lizards hunt deer in packs. But a decade of observations at 10 sites revealed that the dragons essentially never leave the valley where they were born. And DNA data indicate that dragon populations show signs of inbreeding, and they are vulnerable to local shortages of food and natural disasters.

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