People have always been troubled by questions about the world they belong to, about love, happiness, about friendship and the need for others, about history, science, society, about who we are and what makes us truly human - free, free from prejudice. The quantum world, discovered at the beginning of the 20th century, was meant to change the way people think about themselves and their place in the Universe. The quantum domain that ultimately underlies the world has deeply philosophical implications for what we consider to be real and unreal, objective and subjective. Even today, after a century, we try to familiarize ourselves with this challenging world and understand its existential implications.