The Heisenberg Uncertainty Principle is one of the laws of quantum physics. It was formulated in 1927 by the German physicist Werner Heisenberg. It states that the quantum numbers of position () and momentum () are conjugate pairs. This means that if a particle's momentum is more precisely known, then the particle's spatial position is less precisely known (and vice versa), hence causing uncertainty. Mathematically, it is shown by: where is Planck's constant, which approximates x Joule-seconds.