I agree, although you did say "reasonably" hard and it is popularly categorised as hard sci fi. The stuff about using entangled gigantic photons to manipulate s

I agree, although you did say "reasonably" hard and it is popularly categorised as hard sci fi. The stuff about using entangled gigantic photons to manipulate signals to Earth was definitely absurd, but the discussion of the actual three body problem was more reasonable. I dunno. I've never been a huge buff for the harder side of sci fi and Clarke novels seem to leave me cold, so maybe not the best judge of this.