[squeaky-clean]

Science Fiction doesn't have to be fantasy, it can be speculative. But if your setting or plot relies on something we know to be scientifically untrue, and you don't put some effort into explaining why it somehow works in your setting, it's fantasy and not speculative.

Someone like Asimov never considered his books to be fantasy and that he could just insert whatever he wanted with no justification. In fact, he never considered sci-fi to be a genre, he always argued it was a setting and that his most famous stories were detective stories in a sci-fi setting. But detective stories don't work if your world isn't grounded in something real. Otherwise the reader can't reasonably build their own theory or deduce the answer because it's based on what the author thought was cool and not what logically connects.

The appeal of something like The Expanse just falls apart if you introduce a FTL engine just because it makes for a more dramatic story moment somewhere in the plot unless there is some serious justification as to why the author didn't just break all the rules of their world (which is supposed to be our world, but in the future).

[lukan]

"But detective stories don't work if your world isn't grounded in something real."

No, it just has to be grounded in something consistent and if the book starts by explaining the mechanics of the world(or is in a world with known mechanics), a detective story very well can work.

[rdtsc]

It can’t be too different from what people are familiar with. So it has to be consistent with itself and with reality.”It’s like our reality except …” but the except part (faster than light travel, mind reading, time travel, dragons, magic, etc) can’t get arbitrarily complex or unreasonable or the reader will be lost or confused.

[Recurecur]

FTL starships in an SF story don’t need a detailed explanation, just a new invention.

It’s the exact same thing as a speculative story in the 1920s discussing supersonic flight, even though the jet engine hadn’t been invented yet.

For instance “Tunnel in the Sky” bypassed the whole issue in the 50’s, later imitated by “Stargate”…

[wolvoleo]

True but at that point objects travelling faster than sound had been demonstrated.

It was just hard to engineer a manned plane that could do it. For example during WWII the V2 rockets travelled much faster than sound. They were just unmanned. Or more simple, bullets were supersonic for longer too.

What I mean is, nobody thought the sound barrier was a hard limit we could never break.

[Dylan16807]

> But if your setting or plot relies on something we know to be scientifically untrue, and you don't put some effort into explaining why it somehow works in your setting, it's fantasy and not speculative.

Agreed but only because "some effort" could be as little as a single paragraph.

> But detective stories don't work if your world isn't grounded in something real. Otherwise the reader can't reasonably build their own theory or deduce the answer because it's based on what the author thought was cool and not what logically connects.

If you only change a tiny bit, this isn't a major issue.

> The appeal of something like The Expanse just falls apart if you introduce a FTL engine just because it makes for a more dramatic story moment somewhere in the plot unless there is some serious justification as to why the author didn't just break all the rules of their world (which is supposed to be our world, but in the future).

That specific story falls apart but you could have lots of thematically similar stories with FTL. No need for "serious justification" unless you're trying to pull it out of nowhere halfway through the plot. If it's there from the start, there's no problem.

[Frotag]

> No need for "serious justification" unless you're trying to pull it out of nowhere halfway through the plot. If it's there from the start, there's no problem.

Yeah I think most readers care more about consistency than realism. Being completely realistic makes consistency easy but a harder sell in terms of entertainment.

Maybe one way to view consistency is modelling the story world as a network of criss-crossing character threads. Where one axis is time and the other(s) are uh something? Anyways, consistency is how predictable (smooth / linear) the thread is. We follow the main character's thread pretty closely so that thread is allowed to suddenly curve (plot twist) without risk of losing the reader. We only catch glimpses of the supporting cast / antagonist so those have to be either predictable or the narrator has to backtrack and reveal any twists where necessary. And maybe how intricate yet well-behaved this network appears is what gives the feeling of stories coming alive. Or maybe I'm just on too much caffeine and ranting.