I didn't ask you where the word came from. Oxford Dictionary describes chaos as Definition of chaos in English:
1; Complete disorder and confusion:
"snow caused chaos in the region"
It also describes chaos as
1.1 Physics The property of a complex system whose behaviour is so unpredictable as to appear random, owing to great sensitivity to small changes in conditions.
And Friendly, you don't seem to know what Light or darkness are. Darkness is simply the absence of light. And light is a form of electromagnetic radiation!