The Planck constant (ħ) is basically the “resolution” of the universe – the size of the pixels that create our world. This constant is a central physical constant in quantum mechanics, first recognized in 1900 by Max Planck. Planck discovered that physical action cannot take on an arbitrary value. Instead, it must be some multiple of a very small quantity, the “quantum of action”, now called the Planck constant, denoted as h (and in its normalized form denoted as ħ).