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. It is a prototype that precisely defines a ...

The NIST-4 Kibble balance, an electromagnetic weighing machine that is used to measure Planck's constant, and in turn, redefine the kilogram. Jennifer Lauren Lee / NIST Locked in a vault that requires ...

The kilogram — anywhere in the world, for any purpose — is based on the exact weight of a golf-ball-sized chunk of platinum and iridium stored under three glass bell jars in a vault in an ornate ...

For nearly 130 years, the kilogram has been defined by a small platinum and iridium cylinder sitting in a vault outside Paris. Every other unit of measurement is defined by reproducible physical ...

An upcoming change to SI units – due to be officially approved this month – will mark the end of a long journey from defining quantities in terms of objects to using precise, unchanging and universal ...

Using a state-of-the-art device for measuring mass, researchers have made their most precise determination yet of Planck's constant, an important value in science that will help to redefine the ...

Physicists in the US say that they have used publicly available data from global positioning system (GPS) satellites to put a limit on how much Planck’s constant might vary from place to place. Their ...

What does a kilogram weigh? Middle school science classes often teach that the unit is based on the weight of water—specifically a cube of water, a tenth of a meter on each side, at just above ...

Planck’s constant is one of the most important numbers in science. It describes the relationship between the energy and frequency of an electromagnetic wave in an equation known as the Planck-Einstein ...

Lego is a popular Christmas gift, and young and old alike can derive hours of pleasure building with those little plastic blocks. But, like a lot of playthings, the novelty wears off soon enough and ...