Herbert goes into quite a bit of that in the appendices.
IIRC, the sandworms exhale oxygen.
Mentats are trained “human computers,” they do not fold space.
The Spacing Guild uses the Spice to gain prescience to be able to navigate folded space.
There was a sort of collapse of technology called the Butlerian Jihad - the war against the thinking machines. After which, not only were thinking machines outlawed, they were sinful. This did make interstellar travel impossible, until the Spacing Guild came about. That is why all the dates you see in Dune are labeled A.G.
Exactly. He was writing in a rather different frame. Myth in the future, when technology has, in Clarke’s words, become indistinguishable from magic. Some of it is partially understood, much of it has been lost in deep time. Like the abbadingo in Alpha Ralha Boulevard. BTW, run, don’t walk. to your library or bookstore, and pick up Cordwainer Smith’s work if you haven’t read it. It is… marvellous!
Hmm. I’d like to see the chemistry of that. Where do they get the energy and materials from?
Yes, you are correct in story. It is the navigators who fold space, not the mentats. The mentats are a bit disappointing in the book though: we never see a really convincing demonstration of their supposed supercomputer powers.
Yes, that’s a handy get-out, though Herbert never foregrounded it. Perhaps wisely.
As I said: Dune is myth, not hard SF. Read it as such. The later ‘fixup’ attempts were lame, IMHO.
It’s a straightforward reaction: sand (SiO2) is broken down into silicon and oxygen in a reaction with carbon. It takes some extreme temperatures (~1900 C), which sandworms create internally using [mumble mumble]. It does tend to produce a lot of CO2 as a byproduct, but that is easily converted into O2 by LOOK! Over there!
Yeah, poking around various wikis devoted to Dune, reportedly the planet had Earth plants introduced that could survive in an arid environment. So the planet wasn’t totally barren of flora. In addition, it was revealed that the Fremen had already been terraforming the planet in secret, breeding plants, animals, and fish in isolated areas, and bribing the Spacers Guild to keep their fishy mouths shut (since this couldn’t hide from the Guild’s advanced sensors on their ships).
Now, that raises other questions. Is there enough flora to sustain a breathable atmosphere? And how did that flora get a foothold to begin with if it was introduced to a planet that didn’t have it before? It’s easy to say, “There are some desert plants so everything is fine,” but I don’t know if that would actually work in practice.
Also, Arrakis wasn’t ALWAYS a desert planet and the sandworms aren’t native. The sandtrout were introduced from… somewhere, by… someone at some point in the distant past, and the desertification was the result of their thriving and developing into the worm form, which wasn’t possible wherever they were from.
I rather enjoyed Samuel Butler’s satirical book “Erewhon” (which had the idea of machines being alive and evolving – just look at wristwatches over the years).
Science fiction is simply fiction set in the present day or an imagined future (or past, for that matter) that may or may not conform to our current scientific understanding.
Some science fiction does rigorously conform to our present-day scientific understanding. This is sometimes referred to as “hard” science fiction.
Some science fiction veers into more speculative territory, and some goes more into the realm of fantasy.
And as Arthur C. Clarke famously said, “Any sufficiently advanced technology is indistinguishable from magic.” Which for fiction set tens of thousands of years into the future—such as the setting of Dune—tends to blur the distinction between science fiction and fantasy.
Not true. All science fiction is speculative; the whole genre is under the umbrella of “speculative fiction”. What differentiates “hard” science fiction from other types is a matter of subjective relativism; it’s less speculative than other stories in the genre, but it’s still speculative. Otherwise it would by definition not be science fiction, just as @Alessan said.
But if you’re making the point that Dune and stories like it could be less speculative and still be science fiction, you are absolutely correct. Frank Herbert could have tried to ground things better into known science. He chose not to. I don’t think doing so would have been better or worse, just different.
There was also the key point of driving the Ixians to create no-rooms and no-ships, essentially a field that created a space impenetrable to prescience, so that another future prescient God Emperor could never again control humanity. Heretics and Chapterhouse though tended to veer off the most into Heinlein-horny tittilation. “Your sexy lesbian naked soldiers are no match for my 27 orgasmic-addiction seduction techniques! Let’s battle!” I exaggerate only very slightly.
God Emperor was my favorite book of the bunch and the one I’ve re-read most.
While all science fiction falls under the broader category of speculative fiction, some science fiction is more or less speculative than others.
But to my original point to @Alessan, there’s no reason why science fiction can’t utilize “actual science.” The rigorousness of the science in the story (or lack thereof) is not what makes it science fiction.
Sandworms. They produce oxygen. Explicitly stated in Children
Their insides are superheated, chemical factories (possibly nuclear in the big ones, who knows?), and they’re exotic - probably silicon-based - life. So who knows, they probably get it from the rocks they eat.
