So here is something that has been driving me crazy: “What, exactly, is inside a vacuum?”
If you say, “nothing”, you are wrong.
If you say “dust & cat hair”, well… I won’t argue.
If there is truly nothingness, and light (in wave “form”) propagates through a medium, how does light pass *through* a vacuum?
I tried to come with an answer on my own - no dice. But intuitively I knew that it wasn’t really “empty”. Here is a cool breakdown of some of the physics involved. Einstein helped develop the concept of Zero Point Energy which basically relies on the fact that there is “something” inside of a vacuum.