In the field of quantum mechanics, there is a fundamental principle known as the uncertainty principle, which states that there is a fundamental limit to the precision with which certain pairs of physical properties of a particle, such as position and momentum, can be known simultaneously.
Imagine you have a hypothetical particle confined to a one-dimensional box of length L. The particle is in an excited state with a well-defined energy. Now, if you try to measure the position of the particle very precisely, what can you say about the uncertainty in its momentum?