I believe some pretty sketchy things:
Given that I believe all that (I blame years of science fiction and an abortive career in physics.) more reasonable stuff like space elevators and the cure for aging are pretty tame.
But what I never understood about these subjects is how they drive some people to get all, well, starry eyed and religious about them. There is always something about the future that gets people all dreamy. They assume somehow paradise will emerge and everything will get all cleaned up and solved. Then the handwaving starts:
I flatly and categorically disagree with this handwaving. It's handwaving like this that got us into serious trouble in the past. The trouble with most thinking about technological singularities is that it encourages sloppy thinking. A lot of people in futurist circles reach a point in their exposition where they get very vague on how to get from here to there.
Maybe I'm just a curmudgeon. I remember, as a child back in the Seventies, reading these beautifully illustrated essays in an encyclopea about Gerard O'Neill's space colonies and then watching video from the Apollo-Soyouz mission. Even then the juxtaposition was very informative to me. I think what I learned was that the eventually the future becomes the present and the wonderous becomes commonplace and problematic.
I keep harping on this point but, I repeat it here. Heaven is a place where nothing ever happens. This suggests to me that the idea of Heaven and Utopia are logically flawed.
Futurists would do well to avoid this kind of thinking.