When they say "the universe is expanding", what exactly is expanding?

Dark matter. Im not sure if said a bit about it in this.

Maybe the article might interest you anyway seen as your curious about this. But there might not be much about it.

Don't feel the need to click on it beacause its there as im pretty sure it's dark matter. We of course don't yet understand it. The theory as far as I know is that it's sort of like a field of energy.

Smaller than that of atoms or hadrons (protons + neutrons).

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.