veritasium

The new kg is finally here (Patreon)

Published:

2017-07-12 15:39:35

Imported:

2026-06

Tags:

definition kilogram redefined veritasium

Content

Scientists have just published their best numbers for Planck's constant and Avogadro's number. The requirement to redefine the kilogram was three measurements with under 50 parts per billion uncertainty and one measurement under 20 parts per billion uncertainty. What has been published is in fact three measurements under 20ppb with the smallest being 9ppb.

This paves the way to redefine the kg next year as planned using a fixed value of Planck's constant (and the existing definitions of the second and the meter).

Files

How We're Redefining the kg

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 like a kilogram. A physical object seemed like a good idea until the mass of the international prototype kilogram wasn't as constant as expected. These methods of the Kibble balance and silicon sphere have shown better precision than 20 parts per billion, making them superior to the old method. The agreement between Avogadro approaches Special thanks to Patreon Supporters: Tony Fadell, Donal Botkin, Jeff Straathof, Zach Mueller, Ron Neal, Nathan Hansen Support Veritasium on Patreon: http://ve42.co/patreon Interferometer video by TSG Physics: https://www.youtube.com/watch?v=j-u3IEgcTiQ Music from http://epidemicsound.com "ExperiMental1" by Gunnar Johnsén Studio filming by Raquel Nuno