OT: What is the Universe Expanding into?

[Kamog]

There is no way to know for sure whether another creature on earth has pondered the universe and what lays beyond it. We like to think that only us humans are sentient and therefore special, but how do we know that, say, a dog isn't sentient? We can't get into the dog's mind and know what it's thinking.

Well, actually, I must admit that I'm not entirely sure what "sentient" means. I only learned that word in that Star Trek episode where Data had to defend his rights to be equal to a living being. Data had to be intelligent, self-aware, and sentient. So "sentient" is not the same thing as "self-aware". I guess it means something like having consciousness, but I'm not sure.