Why the Kilogram Was Redefined Using Planck's Constant
Veritasium · Explainer · 10 min · 2017 · YouTube title: How We're Redefining the kg
Why it's here
Praised as an excellent, accessible account of why the kilogram's definition changed, in redefinition threads.
What it covers
Veritasium explains why the kilogram is being redefined in terms of Planck's constant rather than a physical metal artifact. It visits NIST to show the Kibble balance and why measuring mass precisely is hard.