At the extremes consciousness can be a side-effect of information processing (neurons firing in our brain causing this feeling of "being me") or panpsychism, the idea that consciousness is fundamental to the structure of the universe (atoms are conscious).

Sam Harris is agnostic on the scientific issue. However while the scientific approach has merits, he thinks our methodology is wrong. We tend to break reality into mind and matter, a Western division that (upon investigation) does not match our lived experience.

Sam Harris didn't try DMT, mainly because he does look at its effects as psychotic. After ingestion (usually through smoking) people are "teleported" to the center of the universe where they claim to meet aliens or angels. This fundamentally different than an "acid trip" (LSD) where your openness to reality heightens. 

Sam Harris's problem with general AI is that it might get to a level where a robot behaves like a conscious being. And since conscious is a scientific mystery still we will have no other option but to believe them. 

Because consciousness is an experience more than an explanation. Life is not a something that can be explained but something that needs to be experienced. 

So we might have perfect imitations of conscious behaviour but we have no way of knowing if that's real or not. 

Sam Harris thinks free will is an illusion. He combined scientific materialism or Buddhism non-dualism to reach this conclusion. 

The practical element is just that hate stops making sense: "If we cannot assign blame to the workings of the universe, how can evil people be held responsible for their actions? In the deepest sense, it seems, they can’t be. But in a practical sense, they must be. I see no contradiction in this." 

Harris argues that once we accept the truth of determinism, we’ll be less concerned about assigning blame and seeking retribution via punishment.