Our quantum story began its troubling history with a detailed look at the nature of light.

The ideas that we refer to as quantum physics began to take shape near the close of the nineteenth century, as new areas of question and confusion arose in the areas of physics called thermodynamics. In particular, two paradoxes were causing quite a stir. One was known as the ultraviolet catastrophe, and the other was called the photoelectric effect. Both issues hinged on the fundamental nature of light, with all of the history of disagreement that had occurred over the millennia concerning it.

Early Greek concepts on the nature of light and vision held that small particles of light were emitted from our eyes, and that we see by virtue of these particles striking other objects. Aristotle expounded this view, and thereby entrenched it into basic science for all time. Some philosophers required that the particles be reflected back into our eyes for an object to be seen, others viewed it as sufficient that the light of our eyes simply hit the object. Besides giving rise to a number of colloquial expressions, this idea persisted through the Renaissance.