For me it is the fact that our blood contains iron. I earlier used to believe the word stood for some ‘organic element’ since I couldn’t accept we had metal flowing through our supposed carbon-based bodies, till I realized that is where the taste and smell of blood comes from.
Heard about it. I initially thought the universe should exist regardless whether someone is there to observe it or not…
…but then I also studied quantum mechanics, so I am not really in a position to say anything…
Well, let’s start with definition what “exists” means…