Heisenberg's uncertainty principle or just the uncertainty principle is a principle in quantum physics which states that there is a limit to how precisely we can measure a particle's position and momentum at a given time. Mathematically, it is stated as where ħ is the reduced Planck constant (or the Planck constant over 2π). File:D5 orbital.png This quantum mechanics-related article contains minimal information concerning its topic. You can help the Physics Wiki by adding to it.