re: I think we need to justify our existence.
I used to think so too, Eri, but existence IS logical, especially now when we have a greater understanding of all the other matter (dark an other wise) that we see today.
What doesn't seem logical is HOW we got here. NASA has a great mini educational documentary narrated by Robert Redford. The entire presentation has to do with collisions and because of them, the universe, the galaxies, stars and planets and especially us, would not be here. Whenever I catch it, I watch I try to watch it to the end. It gave me some chills the first time I watched it.