For this idea, we have to thank quantum physics: it is the idea that particles can exist in both an excited and a non-excited state at the same time, or even exist as two physical objects in separate places at the same time. Recently, it has also shown to be the effect that allows plants use the phenomenon to achieve near perfect efficiency in processing infrared light into energy the plant can use to grow.
In a wider explanation of superposition we could be looking at a fact that also has been proven empirically correct: reality appears to not exist until it is observed, before that moment it is a wave which is a superposition of all possibilities it could be. At the very moment of observation the wave collapses, and the reality is born.