What is electromagnetic radiation made of?
We still use the term ‘electromagnetic radiation’ (EM) even though it is somewhat of a throw-back to before Einstein’s paper, in 1905, on the ‘photoelectric effect’. Since then, it is generally accepted that EM is actually comprised of particles of energy, called photons. This was the first step that led us to Quantum Mechanics. But doing calculations in QM is VERY difficult, if not impossible, and so we do almost all of the calculations regarding EM using the older wave-mechanics ideas, which gives very accurate answers in many cases. To complicate things further, EM actually sometimes behaves like a wave. The truth is that we do not have a clear conceptual understanding of its nature. Still, calling it a particle with some wave characteristics is probably the closest one can get to a description. These particles have zero mass (no weight), have zero size, and travel at the speed of light. They appear and disappear in zero time, when they are absorbed or emitted by electrons. But then
