R&D Mag – The National Physical Laboratory (NPL) has produced technology capable of accurate measurements of Planck’s constant, which is a significant step towards changing the international definition of the kilogram—currently based on a lump of platinum-iridium metal kept in Paris, France.
Planck’s constant is a fundamental constant of nature which relates the frequency (color) of a particle of light (a photon) to its energy. By using two quantum mechanical effects discovered in the last 60 years: The Josephson effect and the quantum Hall effect, electrical power can be measured in terms of Planck’s constant (and time).
A Planck-based kilogram would mean a universal standard that could be replicated anywhere in the world at any time. more> http://is.gd/6rUCMo
- Redefining the kilogram (physorg.com)
- Kilogram conundrum on the road to resolution (blogs.nature.com)
- Replacing our old worn-out kilogram (kottke.org)