Shoot, it doesn't even necessarily mean that we don't have an idea. As far as I know, it just means that we don't have enough evidence to be sure one way or another.
Originally Posted by EDG
"Now everyone was giving her that kind of look UFOlogists get when they suddenly say, 'Hey, if you shade your eyes you can see it is just a flock of geese after all.'"
"You can't erase icing."
"I can't believe it doesn't work! I found it on the internet, man!"