In 2018 the kg will be defined by Planck's constant, not a hunk of metal. Try a free book from Audible for 30 days http://ve42.co/audible Special thanks to the staff at NIST who made this possible: Darine, Haddad, Jon Pratt, Stephan Schlamminger, and Ben Stein. Additional footage and animations by Sean Kelley, Jennifer Lauren Lee, and Frank Seifert. I have been obsessed with measurement for a long time and I'm not sure quite how it happened. The world's roundest object played a role in this. I guess I'm just fascinated by how difficult it is to pin down a quantity...
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