Yesterday as I was writing an overview of Electromagnetic waves (which manifest as radio, heat, light, and more depending on the wavelength) but I left myself with the question of what “stuff” makes up these waves. As I discovered, I can give you two different answers that are, apparently, both correct.
Now, just a quick catch-up for those who missed yesterday’s class: Visible light is but a very small section of the electromagnetic spectrum. The different colours of the rainbow are created by a difference in the wavelength of the electromagnetic wave. Violet is the shortest, while red is the longest wave. These very same electromagnetic waves can get longer to become invisible heat (infrared), or radio waves. On the other side, shorter waves turn into ultraviolet radiation, x-rays, or gamma-rays. It’s all the same stuff, physically, so now I’m trying to figure out what that stuff is.
The original answer defines light strictly as a wave. The wave is created as an electric field interacts with a magnetic field. The wave can travel endlessly through this electro-magnetic field, which exists throughout the universe.
You’re not the only one who thinks that does a pretty poor job of explaining anything. Einstein, Planck and other scientists felt so unfulfilled by that answer that they formulated the whole concept of quantum theory. In that light is not a wave, but rather particles full of energy called photons that can travel at the speed of light. A burning fire would then be emitting photon particles in every direction, and the energy contained in a photon would replace the defining wavelength as the means of determining whether each photon would be the visible orange glow, or the infrared heat.
It’s still not a solid answer to what is the stuff of light, since photon particles have no mass. There’s nothing there, other than “energy”, which could take us on a similarly confusing path to figure out just what energy is. I’ll pass on that one, thanks.
To add insult to injury, there’s a little thing called wave-particle duality, that shows by experimentation (meaning it’s not just some crazy idea, it can be observed) that light is both a wave and a particle. Not that sometimes it’s a wave and sometimes it’s a particle, but in fact that light is both a wave and a particle simultaneously.
At this point, I’m going to simultaneously throw my hands up and give in. It seems I’m not quite ready to understand what light (or any electromagnetic wave) really is in a tactile sense that I can wrap my head around.
To offer a little comfort, I did find this quote from Richard Feynman, who was always very good at explaining things to everyday folks like us:
“We choose to examine a phenomenon which is impossible, absolutely impossible, to explain in any classical way, and which has in it the heart of quantum mechanics.” – Prof. Richard Feynman
- Source: What Is Light? – ThinkQuest
- Regarding wave-particle duality, here’s a good animation explaining the oddness of the “dual slit experiment” (YouTube video)
