I'm gonna get philisophical on you here, so bear with me.
At what point do we stop writing off every nutjob with a theory that sounds more like Saturday morning cartoons than fact? There are a million different theories and ideas out there, and I think it's pretty damn cocky to think that we have a handle on the world (and everything) today.
Everything from the theory of life, the universe, and everything, to 9/11 conspiracies, to the theory of relativity.
Let's start with science. Time and time again we find out that what we "know" as fact is wrong. For instance, once upon a time, we "knew" the world was flat. We "knew" that the Earth was the center of the universe. We "knew" that the Sun was the center of the universe. We "know" that we can't travel faster than the speed of light. We "know" there is a God who watches over us, and loves us, and needs us. Yes, Einstein was probably the smartest man within at least the last 100 years, but what if he was wrong? Is it really so impossible? We know so little about the universe. Is string theory right? Probably not, but some of its fundamental ideas are intriguing. I guess what I'm trying to say is that we don't know. Not only do we not know, but we very well may never know. We go through the motions every day, waiting... hoping... working... for what? for whom? We're so cocky. We're so all-knowing. We're so sure.