There are always those people - those in which you never feel you'll lose. Those who will be around forever and then some. Those who know you almost as well as you know yourself.
What happens when those people disappear without a trace? What does one do? What do YOU do?
You hurt.
Sometimes not knowing is more of a curse than knowing. Knowing if these people are alright, knowing what happened, and why it happened, as hard as it may be, is nothing compared to knowing nothing and having nothing but your fading hope that they're alright.
Silence is the worst torture of the mind. It steals all peace from the world, and constantly nags at your sanity, draining all energy you have to put towards your normal endeavors. There's another word for a pain of this level.