I don’t remember this sequence, but I do remember that there was a lot of alien-induced hallucination happening in the book. Is it possible that that’s what was happening there?
The book is not hard sf in the sense that everything that happens is perfectly supported by today’s science. But it is hard sf in the sense that science is the main character, and even when the science isn’t good, the author spends a long time detailing how it works.
Ah I thought that was a possiblity, so they were allucinating a lot, no wonder I DNFed the book, that kind of thing tends to bore/irritate me to tears.
I thought it was quite entertaining, but I would certainly not call it ‘hard’ SF. I mean, expanding protons to macroscopic size and having them behave as bot machine weapons? Come on! It’s more reminiscent of the ‘superscience’ stories of early SF where gee-whizz was more important than any actual science.
Though maybe there was an allegorical or satirical side to it that I missed?
The explanation of the hallucinations is pretty interesting, IIRC. Rather than the usual mumbo-jumbo, the hallucinations
are caused by self-propelling highly-AIntelligent nanomachines that can move at nearly the speed of light and are, in three-dimensional space, the size of a proton. Each “sophon” identifies theoretical physicists and traces patterns in front of their eyes that appear as hallucinations, either driving them suicidally insane or disrupting their research findings. The aliens know it’s gonna take a few centuries for them to reach Earth in order to launch their invasion, and they don’t want human science to advance significantly before they arrive.
Yes that makes sense, but I was never going to like the book then, I hate books were the protagonist/narrative point of view are not sure of their own perceptions.
To quote NPR:
“Scientifically rigorous” might not be the right phrase: but “obsessed with science” would be. Here’s a pretty interesting blog post by a working physicist discussing some of the scientific flaws with the book.
If your definition of “hard sf” is that the author takes no liberties with current scientific understanding, then this book definitely doesn’t qualify. But I just don’t think that’s what most people mean by the term.
I’d be inclined to say that, in a ‘hard SF’ book, the author should not use any concepts or situations which contradict current scientific understanding, unless they have a plausible future extension.
Of course, we usually have to allow at least ONE McGuffin (usually FTL travel) to get the story started!
I humbly suggest that 3-body problem is harder, by this definition, than anything with FTL.
But returning to the OP’s definition–
3BP absolutely qualifies 
I’ve heard a hard SF writer say that you can have ONE unscientific thing (faster than light travel, artificial gravity, etc) but that everything else must be straight science and the responses to the one unscientific thing must be realistic.
I don’t know if that’s a hard and fast rule. Project Hail Mary was great, but it had a few unscientific things:
the microbes have to be made of unobtanium and have magic power over the strong and weak nuclear forces if they’re going to use matter-antimatter reactions for propulsion and survive the sun
the aliens have that whole “solidified noble gasses used as a super powerful metamaterial” thing, and one alien on a spaceship is able to handmake anything they need because the stuff is so easy to fabricate
There are other examples as well, but those two are basically at a Star Trek level of handwaviness. But that’s fine, and the book is still definitely pretty hard science fiction.
Well, if you’re aiming for hard, near-future sci-fi, I can suggest Daniel Suarez’ Delta V, which is about pioneering asteroid mining.
But I have to say that with a caveat. Personally, I found the plot and writing a bit melodramatic, and…I’d have to call it “bloodless.” Not dry—I’m a happy connoisseur of “dry, technical” works—just…anemic, a paucity of genuine life or spirit to it.
You can write all the technically accurate machinery in the world, have all their math check out to the hundredth decimal, but you still should be able to pinch them and see a decent cap refill.
It’s funny… I’m about two thirds of the way through 3BP right now, and if it wasn’t for this thread and some of the blurbs on the book cover, I’d have no idea thus far (except for a couple of hints here and there) that this is an “alien contact” story.