ryan93 wrote:
If there was any number I could know, it would be the value for fℓ. The drake equation is beautiful. I have no interest in ever seeing an Alien though, natural selection breeds killers

As for my own theory, I think that consiousness is little more than what happens in a system of sufficient complexity, and that it isn't necessarily just specific to biological systems.
Quite an interesting thought, mind if I expand on it a bit? Our bodies recycle most of their atoms over time, even those in the brain. At some point in your life, your brain will not contain a single atom it had when you were born. And yet you're still you. Therefore it must be the structure that allows for consciousness. To mutilate a quote from a Discworld book, you cannot grind up the brain and sift out one particle of consciousness, one molecule of sentience.
And yet, variations in the structure still allow for conscious experience. We're different than NT's in how we're wired, and yet we experience consciousness (though, whether we experience it the same way is an interesting question). People can sustain massive brain damage and still be conscious. I see no reason why stranger structures still could not be conscious as well.
Though, with all this talk of consciousness, it seems nigh impossible to suitably describe it, as it is all we experience. We have no real concept of what it feels like to not be conscious, for if we did we would be conscious. Can consciousness be divided or merged? Who knows...
My speculation on the subject is that consciousness is the result of some intrinsic property of the universe, either as some as-yet-unknown energy field that interacts with systems of electrons (the more complex the system, the more intense the interaction) or as some strange quantum phenomenon. I have noticed through my brief experience with meditation that consciousness can just about entirely separate itself from thought - I appear to be neither a thing of the body or the mind, but something looking in from the outside, like a child playing an immersive video game. To quote Babylon 5, "The soul is a non-localized phenomenon".