Well, it's really controversial and controversial, and despite the studies there are still things that are beyond our understanding. As the beginning of the world we know, although that is only the beginning since we are tiny in the middle of the entire galaxy. The existence of the soul as such, although for some it is only the essence of our own mind and brain that creates us allusions of nonexistent things. The truth is that there are still unfinished things, in my personal experience I tend to be very objective, but I had a "paranormal" experience that escapes all ability to understand and even today I wonder if it was the product of my own mind or if it really exists something beyond, spirits or demons surrounding and tempting us (luckily I was accompanied so I was not the only one to see a spirit) But I wonder, if there is still much to be explored today in our own world, for example the extensive seas, how can we affirm things as tangible facts, when there is still much to know.