We can fix the value 1 for the velocity c and write, for example, v = ½, for a body that is moving at half the speed of light. In the same way, we can posit LP = 1 by definition and measure length in multiples of Planck’s length. And we can posit h = 1 and measure actions in multiples of Planck’s constant. In this way, we have a natural system of fundamental unities from which the others follow. The unity of time is the time that light takes to cover the Planck length, and so on. The “natural unities” are commonly used in research on quantum gravity.
