# Reflections at Interfaces
I was reading a book my sister in law let me borrow called To Measure the Sky (opens new window). It's an introduction to observational astronomy, and I find learning about light interesting and useful.
I've been thinking about my last blog post, especially how it helps me organize my thoughts and make reflections on and of myself. It's like rather than looking into a mirror, I can see my reflection in the words I type. My computer is the mirror I use for self reflection beyond just my physical appearance; my reflection in my minds eye.
The first few pages of the book I'm reading explain the modes of behavior of light. The summarization of the wave theory of light mentioned "Light exhibits all the properties of classical, well-behaved waves, namely: reflection at interfaces..."
Huh. I thought I knew what interface meant. In programming terms, it usually describes how a class or function will behave. It can also mean a point at which humans interact with a computer, such as a touch-screen interface or a graphical user interface. I hadn't really heard the word used in the context of the behavior of light. I set out to answer the question: what does it mean when light reflects at an interface?
"Hey Google: define interface."
"Interface has 4 different meanings. Starting with the most common one, interface can be used as a noun to mean a point where 2 systems, subjects, organizations, etc., meet and interact."
Another coincidence. I previously described myself as a complex system, similar to a computer. I would like to compare myself as a being of light, and a well-behaved one at that. Maybe all this self-reflection I am doing is in an abstract sense just light reflecting off of complex systems. In the case of writing my blog, it is the light of my thoughts reflecting at the interface of a computer.
But the complex system isn't necessarily the computer. It's the words, or rather the language that is reflecting my thoughts. So far I count 4 complex systems in this process of self reflection: body and mind (self), my computer, and the words (language). Between this arrangement, my ideas are reflected in a recursive process of self reflection. This complex system is my blog.
Comparing my blog to journaling, we can see the simliarities. In this case, I count 3 complex systems: my body and mind (self), and my journal entries (language). This (not so) complex system is my journal.
Therefore, I have two backup systems beyond my own thoughts that facilitate self-reflection. Coincidentally, I notice the same recurrence of backup systems in nature. For example, two lungs, two hemispheres of the brain, two nostrils, two eyes, etc. Even Tesla's self driving computer (opens new window) has redundancy.
Interesting. I like to think we are more like computer systems than you would suspect. If so, the ability to code and self reflect are powerful skills, indeed.