David Chalmers shedding light on Consciousness

I am still reading his book (The Conscious Mind), but I keep getting stuck in the basics and find it hard to proceed. I just can't easily come to grips with Chalmers' arguments about consciousness and what it is, or rather might be. In the section of the book called "Foundations" he talks a lot about logical or metaphysical conceivability and about supervenience. Lacking philosophical education, I hardly know what he is talking about. He says that because he can imagine a being which was physically identical to us in every way, except that it lacked consciousness, then that says something about consciousness. I can sort of imagine a universe where time stops for a thousand years, then runs for for three seconds, then stops for a thousand years, then runs for three seconds, and so on ad infinitum. Of course, our universe might be doing that right now, but we would never know. That says nothing about time at all. Because Chalmers can imagine a philosophical zombie, he thinks he can draw conclusions from that. I just don't get it. Thought experiments are dangerous things, I think - they can deceive as well as enlighten.

PS I can't sleep, that why I am blogging when I should be sleeping.