My take on hard sci-fi is that it must either use science and technology that we already understand, in ways conforming to that understanding, or - if it presents new technology that is posited as something beyond our understanding - it must be consistent, including other "magic" as well as interactions with things we do know. Some examples of what I would consider hard sci-fi: "Tau Zero", "Tales of Pirx the Pilot", "2001", "Seveneves", the Mars trilogy.

All of these components are lacking in the book, and it's not just the particles. It reads very much like someone subscribed to some popular science journal for a few years, and then just dumped every idea that sounded interesting into a book without much understanding of what it is about.

To give another example, the author references string theory - great! - but then he has a one-dimensional string - that makes up an elementary particle - break apart into "pieces" from gravity.

Or take alien propulsion. It supposedly works by collecting antimatter from space - but where in space is there enough antimatter to collect like that, and why hasn't it annihilated from interaction with the much more prevalent hydrogen? The interesting thing about this example is that it's not insurmountable - hard sci-fi could explain it away in some convincingly sounding way - but the book doesn't even bother to, it's just presented as fact, without even pointing out the contradictions.

It's not dismissive to call it fantasy.

Do we have any scientific evidence that any of higher-dimensional antics in 3BP are possible?

If not, then the author is making up his own world building rules (completely acceptable). But that makes the story more akin to scientific fantasy than hard scientific fiction.

And unless the English translation excised a LOT of technical details, there are some huge leaps of scientific faith in 3BP.

There's a rule I remember, that in hard-ish sci-fi, the author gets to invent one unrealistic thing. I wouldn't put Cixin Liu's trilogy as hard hard sci-fi, as it invents a few more, but all in all, there aren't that many "fantasy devices" there. It definitely has a flavour of hardness.

> I wouldn't put Cixin Liu's trilogy as hard hard sci-fi, as it invents a few more, but all in all, there aren't that many "fantasy devices" there. It definitely has a flavour of hardness.

Even that much is being overly kind (at least to the first book - I gave up after that). Hard SF introduces a small number of well-defined ideas and then works through their logical consequences. Science fantasy introduces magical devices with particular consequences as and when the plot demands. The magical VR system and magical particle computer - essentially all the SF elements of Three Body Problem - were examples of the latter.

The second two books definitely approach it more closely.

I guess the piercing of my suspension of hard sci-fi disbelief happened in the 2nd book(?), where post-Fall they rebuild into a militarily space capable society with relatively advanced weaponry.

If you're going to take 1,800 pages (English translation) to lay out your series, and you can't spare a few for 'well, now we're building giant fusion-powered warship fleets'? That's not anything approaching hard sci-fi in my book.

Yes, all the technologies used on the ships are extrapolated and believable, but the realignment of society, economics, and the organization of such a construction effort boggles the mind. And to say 'it just happens'? That's kind of like going from WWII to 'and so we landed on the moon' in a single page.

Fair. The time jumps were a bit jarring, though I guess I got used to those after a similar one pulled in Seveneves. I wouldn't mind if Cixin Liu shortened some parts of his book and used the reclaimed space to fill in those time jumps a bit, though.

They get to invent as many "impossible" things as they want, really. But they all need to have plausible-sounding explanations (given our current level of scientific understanding), and they need to act in a consistent, predictable manner, including consistency with known laws of nature - e.g. if you have antigravity, the default assumption is that it obeys the inverse square power law, and if it doesn't, that needs to be called out and have some explanation of its own.

I'd hew closer to TeMPOraL's definition.

On the one hand, one obviously needs some technological leeway to write a fun novel set in the future.

On the other, if every roadblock is responded to by suspending scientific treatment, it doesn't seem like that's a good faith "hard" effort.

I think Ringworld is instructive. The Wikipedia article specifically calls out technical inaccuracies in the original... inaccuracies Niven specifically made an effort to patch up in later books.

So the count of intentional lapses seems as decent a proxy for hardness as anything else.

I would consider Ringworld to be borderline hard sci-fi, but precisely because it has some reasonably sounding explanation for his technomagic. E.g. the General Product hulls - them being a single macro-molecule is a reasonable pop-sci explanation for their properties, even if the book doesn't explain how such a molecule is made. Does that count as an intentional lapse?

What are your thoughts on Diaspora? (Greg Egan)