The kilogram has officially been redefined

These redefinitions have been in the works for some time. "This is the most important decision that the BIPM has made in maybe 100 years, which may be a slight exaggeration, but at least since 1960 when they adopted the International System of Units," said Terry Quinn, emeritus director of the BIPM. And while the changes won't necessarily be reflected in your day to day life, they'll help scientists make more accurate measurements going forward.

The kilogram will now be defined by the Planck Constant, while the ampere, kelvin and mole will be tied to the elementary electrical charge, the Boltzmann constant and the Avogadro constant, respectively. "It's about as excited as you're going to see metrologists get," David Newell a researcher at the National Institute of Standards and Technology, told Science News. "I can't believe we're finally getting it done."

The new definitions will be put into place on May 20th, 2019.