Super exciting!

Finally, a fundamental definition of a kilogram!

Scientists at the National Institute of Standards and Technology have now officially defined Planck's Constant as 6.62606983 * (10^-34) (kilograms*meters squared) per second. A second is already fundamentally defined as 9192631770 cycles of the radiation produced by the transition between two levels of the cesium 133 atom. A meter is already fundamentally defined as 1/299792458 of the distance light travels in a vacuum in said second, the speed of light also being a fundamental constant of nature. From these two things, we can now back out a fundamental definition of a kilogram, which we could communicate to aliens on another planet, and they, too, would know what a kilogram was.

Until now, most of the measurements we use have had such fundamental definitions, which were universal and describable in words. The kilogram, in contrast, had been defined by a very specific bar of platinum and iridium, declared as such in 1889 by the General Conference on Weights and Measures: "This prototype shall henceforth be considered to be the unit of mass." It's kept in several protective layers of extremely protected, micromanaged, environmentally monitored vacuum-sealed safes, and they have found somehow that recently it's been losing mass, or perhaps its doppelgangers, created and shipped around the world for calibration, are gaining mass. Either way, to define a kilogram as such is terribly inelegant, ephemeral, and specific to our species, place, and time.

How much more beautiful to say, "A kilogram? Why, Planck's Constant is 6.62606983 * (10^-34) (kilograms*meters squared) per second!" instead of, "Uh, please board your rocket ship and fly over here as fast as you can, and measure our special bar here. See you in 8000 years!"

:~D