c: the speed of light in Vacuum

• The Planck constant is one of the fundamental constants of quantum mechanics. Quantum mechanics shows us that energy is exchanged and absorbed in specific amounts, known as “quanta.” h defines the size of those quanta, which can be visualized as packets of energy exchanged by matter. • In the revised SI, the Planck constant h is equal to exactly 6.626 070 15 × 10-34 Joule seconds. This value for the Planck constant was only finalized in 2017, and that value is key to redefining the kilogr...