How a Silicon Sphere Helped Redefine the Kilogram
Veritasium · Explainer · 12 min · 2013 · YouTube title: World's Roundest Object!
Why it's here
Recommended in kilogram-redefinition threads as a clear, short explainer of the Avogadro and Planck approaches.
What it covers
Veritasium explains the effort to redefine the kilogram, which was still defined by a physical artifact, and how a near-perfect silicon sphere from the Avogadro project helps. It also covers the history of the unit's odd naming.