Rhett Allain has a list of 5 Things Every Human Should Know About Light, to tie in with the International Year of Light, and it’s a good list with lots of .gifs. Of course, there are some gaps, so let me offer some additional things that everyone ought to know about light:
— Light Is a Particle
Rhett and I have a long-running argument about the use of photons in introductory physics; he’s against them for reasons that make no sense to me. To my mind, it is unquestionably true that light has particle-like properties (and here’s a follow-up with some math), and that’s a thing that everybody ought to know.
— Quantum Physics Starts with Light
So, Rhett says light is a wave, and I say it’s a particle. which is it? Well, both, really, and that discovery drove the development of quantum physics, as explained in this video:
(Or you can read the approximate text here)
The particle nature of light was introduced by Planck, and refined by Einstein, and the wave nature of matter starts with Bohr’s quantum model of hydrogen, which was needed to explain the light absorbed and emitted by atoms. So, quantum physics is all about light.
And quantum physics is essential to, well, everything. Understanding the quantum physics of light and matter lets us build lasers and semiconductors, which are essential for modern telecommunications and computing. You wouldn’t be able to read this if not for light leading to quantum physics.
(More in this vein: Four Things Everybody should Know About Quantum Physics and Seven Essential Elements of Quantum Physics. And if you prefer video, here’s a TED-Ed animation about Schrödinger’s cat and computers.)
— Everything We Know About the Universe Comes From Light
This isn’t just a statement about our heavy reliance on our eyes for getting around the world. Pretty much everything we know about the origin and fate of the universe comes from studying light. We can even use light to detect the existence of stuff that doesn’t emit any light:
See also this Tor.com article I wrote about spectroscopy, jumping off from Gandalf’s assertion that splitting white light to study it departs from the path of wisdom. Far from it– splitting light is behind some of the most amazing discoveries in the history of science.
So, in summary, light is awesome. The more cool things you can know about it, the better.
(“Featured image” from Russel Dickerson’s site, because it amused me.)