Science has helped humanity probe the deepest recesses of the universe, and the tiniest particles of matter. It has taken us to the moon and radically increased our lifespans. But until now, it has not asked the ultimate question: why is it that Justin Bieber cannot seem to open his eyes fully? I mean, the guy is squinting in practically every photo ever taken. We gathered scientists from every field to tackle this enduring mystery, and peer reviewed their hypotheses out of their eyeballs. Behold: the surviving theories.