what i’m writing… a sample…

At the end of the 19th century, physics was considered by many to be a done deal. The methods of classical mechanics had proven successful in describing the motions of objects at the large scale — so much so that in 1846, tiny discrepancies in the predicted orbit of Uranus were used to pinpoint the location of a new planet: Neptune. The methods of statistical mechanics were bearing fruit in the description of the microscopic behavior of matter. And thanks to James Clerk Maxwell’s unification of electric and magnetic phenomena into a description of light, it seemed like we had explained all the phenomena in nature that needed explaining.

The only really important questions that remained for physicists to answer revolved around the interaction between light and matter. Maxwell’s Equations did a reasonable job at explaining how this interaction happened on a large scale, at low frequencies. For example, if you have a wire full of electrons and you jiggle those electrons back and forth with an alternating current, those jiggling electrons will produce an electromagnetic wave. That’s how a radio transmitter works. If that electromagnetic wave should travel though space and happen upon another wire full of electrons, the wave will jiggle those electrons around in that second wire much the way the original electrons were jiggled. That’s how a radio receiver works. Not too long after Maxwell published his equations of electromagnetism, Heinrich Hertz used a spark to send a short blip of a radio signal the length of his lab, confirming the existence of electromagnetic waves and their relationship to moving electrical charges. It was only XXX years before Marconi and others developed the technology to use radio waves for communication.

It seems like it wouldn’t be too hard to extrapolate this sort of behavior to explain, for example, why an object gives off light if you heat it up enough. After all, the motion of electrically charged particles can create electromagnetic waves. And matter is made of atoms that are buzzing with charged electrons. So it’s not hard to imagine that when you heat something up, you knock the atoms around, the electrons jiggle about, and that causes a high-frequency electromagnetic wave to be emitted – light!

The opposite sort of interaction is easy to imagine as well. Think of a photo-electric solar panel, which turns visible light into electrical current. How might that work? Well, light, which is made of oscillating electric and magnetic fields, strikes some sort of material called a “semi-conductor”, which sounds like it means that the electrons are almost-but-not-quite able to flow freely. So the jiggles of energy imparted by the light shake those electrons around until they are free to flow through the material, creating an electrical current.

It seems like it would be a simple matter to go from understanding how an antenna emits and absorbs radio waves to understanding how the individual atoms and molecules in a material emit and absorb light.

It wasn’t.