Okay, so let's say we have a one-dimensional box of some width with a particle inside. If the particle is in an eigenstate of the energy, we know its energy exactly. Since the energy is purely kinetic, we also know its momentum. By the uncertainty principle, the position should be infinitely uncertain... but we know that the particle is in the box (hence a finite uncertainty). How does this work?(adsbygoogle = window.adsbygoogle || []).push({});

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# One-dimensional box of some width with a particle inside

**Physics Forums | Science Articles, Homework Help, Discussion**