The greatest mystery in the universe is the nature of consciousness (the greatest mystery of all is why there is even a universe, but that's for another entry).

By this I mean: how can a collection of matter be self-aware? Put another way, when does a collection of inanimate particles become animate? And at what point does it become so? If it's solely due to complexity, at what point does complexity render something conscious? And what does that mean for matter whose level of complexity is slightly below the "consciousness tipping point"? What state would it be in?

There are levels of consciousness as well. My cat is conscious: he is self-aware, knows when it's time to be fed, has a well-defined sense of the boundaries of his territory. But his level of consciousness is less than that of humans who can contemplate the wonders of the cosmos (and before we get too haughty, whose to say our level of consciousness isn't superseded by an advanced race whose knowledge of what really exists lies as far above us as our knowledge lies above a cat's?)

It's always bothered me when people say conscious life exists elsewhere in the universe simply because there are so many planets out there. There are a lot of planets out there, but it doesn't follow that any of them contain advanced civilizations or conscious life of any sort.

Proponents of conscious life are playing a numbers game: with billions of planets suitable for life, they say, there certainly must be life out there. And conscious life. Advanced civilizations. That's were the leap of faith comes in. We simply don't know at what level of complexity consciousness arises. It may be a once-in-a-universe event!

There are billions and billions of planets out there. Yet the enormity-of-numbers-sprinkled-with-the-faith-of-randomness argument doesn't lead where its proponents think. Most people have no idea how quickly the randomness game grows.

I certainly hope the universe is teaming with life, but I don't want to be disappointed if we discover that it's not.