The Plank Constant in Quantum Mechanics

There is a constant of proportionality, which we call the plan consternd. Without this relation, you can't calculate the energy of the forton. That's the relationship between the energy and the wave lank This is where quantum mechanics begins, right? It's max plank who discovered this,. so to say, t the at the end of the nineteenth century, i believe, or at the very beginning of the twentieth century.