TAKING MEASURE New units based on fundamental properties of the universe will make measurements more precise. A kilogram cylinder replica (left) is safeguarded under bell jars. Ultrasmooth silicon spheres (right) will soon be used to redefine the kilogram using the Planck constant — making the kilogram prototype obsolete.
epa european pressphoto agency b.v./Alamy Stock Photo
If scientists had sacred objects, this would be one of them: a single, closely guarded 137-year-old cylinder of metal, housed in a vault outside of Paris.