Schrödinger's cat
The Copenhagen interpretation is used to explain what is happening to the smallest part of an atom (a sub atomic particle) without looking at it (observing it or measuring it). Mathematics are used to show how likely something is to happen to the particle. A particle could be described as being 50% likely to be in one place at one time, or 50% likely to be in one place at another time. This could also be expressed as a chart (or wave form). This is very convenient when making quantum physics calculations.