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Comment by bluGill | Hacker News Reader

Science fiction almost universally assumes the speed of light is not a hard limit. At this time we have every reason to believe that it is a limit. Our theories also say that if you were to go faster than light (which you cannot) it implies time dilation and time travel - again science fiction just assumes a loop hole so that doesn't happen.

Many talk about travel at 10 times the speed of light (warp-10) as if that is fast, but if you actually notice that lack of aging during travel they have to be traveling much faster than that. (at 10 times the speed of light the nearest star to earth is just under a 1 year round trip - your kids would not remember you very well when you return)

Which is to say that any aliens with space travel that discovers us now will not be making the journey because the length of time it would take.

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> Science fiction almost universally assumes the speed of light is not a hard limit.

Not at all, you need to look at other sub-genres. The social, economic and military structures that form around slower than light travel are a mainstay of hard science fiction. "A Deepness in the Sky" is a great example. So is the first half of "Neptune's Brood" or the second half of "Accelerando". Any story that uses a generation ship as the setting, like "Hull Zero Three", also assumes sub-light travel. Or what would happen if present-day society discovered an alien race next door, like in "The Sparrow". Or maybe we need to make ourselves slightly less human to survive sub-light space travel. "Blindsight" and "Echopraxia" explore the philospohical ramifications of that. Even "Ender's Game" doesn't have FTL travel.

Now space opera almost universally assumes that FTL is possible. Though there are exceptions, Ian Banks "The Algebraist" is my favorite sub-light space opera.

edit: Some hard sci-fi will still use wormholes, either as a normal thing or a macguffin. FTL communication is also common. Though FTL comms are getting less common in modern hard sci fi. Us readers like this and it makes for convenient plot devices as comm lag leads to misunderstandings.

TV and movies are almost always space opera, with "The Expanse" being the only sub-light TV production that comes to mind, and "2001" for film. But I don't know as much about film as books.

Just wanted to mention The Expanse, which definitely has hard limits on going over (or even reaching) the speed of light, and touches on many of the tropes you mentioned. It's also probably one of the best examples I've seen of a truly alien encounter- no bipedal humaniods with spoken language.

The book series is excellent, and it has two seasons released from SyFy, which does a pretty good job capturing the feeling the books.

Coincidentally I'm working through the book series right now. It is mostly good, though it would be nice if the main characters weren't quite as consistently lucky.

The author's handling of energy is really annoying. I can overlook the structural impossibility of spinning up an asteroid for example, but I can't overlook the fact that they can command that sort of energy. It is made even more frustrating because they understand the offensive capabilities of kinetic weapons and rocket exhaust.

For example, the mirror array on Ganymede was stupid. The greenhouses use electric lighting for half of the time anyway, when behind Jupiter. Why build this giant orbital mirror array when you could install a second fusion reactor instead and leave the lights on all the time? And then it could all be underground too.

Magnetospheres make some locations very desirable. Why not lay down some super conducting cables, hook up a fusion reactor to it and make your own magnetosphere? This would have been a great plot device too, since any rich civilized place would do it, but it also makes detection of the habitat trivial. Poorer places would keep their's off and take the risk of cancer, turning it on only for protection from solar flare bursts. Seedy places would never install one at all.

If you're interested in the science behind spinning asteroids, check out https://en.wikipedia.org/wiki/Yarkovsky%E2%80%93O%27Keefe%E2...

That has nothing to do with what I'm talking about. In The Expanse, they hollow out and spin up asteroids to use as a space station with centripetal artificial garavity. A typical rubble-pile asteroid would fly apart well before that. Even solid rock couldn't take the forces since they are all tensile.

In the novels, it's described how the asteroids like Ceres have been reinforced internally for precisely that problem. Now the energy requirements to spin up something that massive, that's another issue.

Sorry, I thought you (or the other people reading this thread) might be interested in how asteroids behave in the real world. I wasn't saying that's what was happening in the show.

I didn't mean to come off sounding so harsh. YORP is fascinating stuff, particularly when it can happen to such an extreme degree to make a stable asteroid break up.

I find YORP interesting because it makes things change in a part of the solar system that otherwise might be pretty boring... a lot more interesting than slowly outgassing volatiles and maybe an occasional collision.

How do they zip around the solar system so quickly? It seems like at various points they go from earth to where ever almost instantaneously (in the show, that is).

Not a troll - I'm genuinely wondering what I missed from the episodes.

Basically the Epstein drive allows for basically unlimited thrust, which is what gives most ships on the show gravity. Unlimited thrust == unlimited acceleration. When they reach the halfway point, they 'flip and burn'; turning around and start accelerating away from the destination to slow their relative velocity.

Ships get around the solar system using a propulsion system called an Epstein Drive. I just watched the following video yesterday. The narrator talks about travel times to different planets using a flip and burn technique (accelerating at a constant rate to half way point flipping direction, and decelerating at the same rate to the destination).

https://youtu.be/hz7jETrejCQ

P.S. I love the Expanse :) I'm glad it was renewed for Season 3. Best sci-fi I've seen on TV since Battlestar Galactica.

In the books, the sense of time it takes is conveyed. I don't think they're treating it as instantaneous in the show; just that they're keeping the story moving along because it makes for better TV. If you like the show and you like reading novels, I highly recommend the book series.

Same as in most tv shows, they skip the boring bits.

Travel times are mentioned occasionally and they are consistent with ships that can do a brachistochrone orbit at a constant 0.3 or 1f acceleration. This would be a few days between most locations mentioned iirc.

spoilers It sounds like you may not have read all the books yet.

Everyone says that after book 3 or 4 they go downhill anyway.

I like to believe there was only one Matrix movie ever made and only one Dune novel. I will probably prefer to believe that there were actually 9-N books in The Expanse series, where N has yet to be determined.

I'm rereading the Dune series right now and on Children of Dune. Actually REALLY enjoying the 2+ books more than the first. What would one do if one had become a human god but didn't like the future he saw?

Like the post-Ender's books (before Card sold out), I find mulling over the consequences of upsetting an applecart far more interesting than the upsetting.

The first books in both series feel a bit too "Mission Accomplished!", pat-on-the-back in hindsight.

For me it is all about the world building, the practicalness of the universe presented. Dune had a decade of planning go into it before the first book was written. The rest did not have that amount of background effort and it shows. After the first book it all feels like he's making it up as he goes along, instead of drawing on an encyclopedia.

Children of Dune had the most egregious problem with this. Trying here to not spoil the plot for you, but at towards the end (page 329 of 408 in my edition) Leto discovers something profound. The backstory to introduce this was first mentioned on the previous page. It didn't use some bit of trivial from the first two books, and he couldn't be bothered to write it 300 pages earlier either. (Feel free to email me when you think you've reached that part.) The later novels are slightly better, then he's writing these new discoveries into the previous chapter.

Re-reading Dune has always been pleasurable for me. You can feel it is just the tip of an iceberg and tease out the history by reading between the lines. The other books lurch from one deus ex machina to another.

Ender's Game is also largely about consequences too. Humanity wins the fight and destroys the big bad, but this doesn't happen at the end of the book. There is still a third of the story left to mull over the consequences.

edit: Slight spoilers, but nearly all of the later Dune books essentially allow anyone to come back from the dead. He never once explores the ramifications of this. What happens if you try to bring back multiple copies of someone at once? Does every cell in our body really carry the full weight of our entire past experience? What about identical twins? What if you blended the nucleus of one person with the mitochondria of a second and the cellular plasma of a third? Or does the procedure somehow tap into the soul? Is god annoyed that the natural cycle is broken? Does the process damage the soul? Never once delves into any of this, instead it is used only as a cop-out to avoid creating new characters.

I hear what you're saying. I'm gradually arriving at a model of "good book" that includes what a person's particular transgressions of suspensions of disbelief are, and what degree is required to trigger them.

For me, the biggest things are currently "must be at least this hard sci-fi" and "must have believably human characters." It sounds like one of yours is "must have book-spanning world-building." Which I get, but don't think bothers me as much.

I expect the unexplored deus ex machina will probably irk me when it shows up though! Though maybe not, I think a large part of my enjoyment of Dune is the somewhat orthagonal-to-Western world-building. Although the Islamic religious echoes are ham-fisted and shallow sometimes, it's still refreshing to even read something attempting it.

By my memory, Ender's didn't mull over consequences nearly as much as Speaker for the Dead, Xenocide, & Children of the Mind. It was more "Oh my god, this was horrible" and less "We did a horrible thing, so what do we do now? And how does that inform our reactions the next time we're presented with the same choice?"

Side note: if you ever want to read something laughably bad, especially for how modern it is, read one of the Honor Harrington books from David Weber. I tapped out after 20 pages.

Maybe world building is the wrong term? I consider civilizations, economics, infrastructure, etc, as another character in the story. They have background and develop over time. They should be as believable as the humans. This is common in the "future history" sub-genre but you find unexpected gems too. Discworld was remarkably good about it, for example.

Just found my copy of Ender's, one of the few OSC books I still have. I got the proportions very wrong. The story was "over" on page 295 of 324. So like 9%, the entire last chapter, was about the aftermath. Mostly Ender dealing with what happened. Still way more than the usual "happily ever after" and sequel hook you normally see, to give it credit.

The Honorverse is the purest of space opera. I have too many good memories to agree with you, but I won't push my luck with a re-reading. I seem to recall that it actually was pretty good at having their magic super weapons, drives and shields progress reasonably over the series. Weber was very good about having military tactics shift in step with the technology.

That's a more detailed way of putting what you're looking for. And I enjoy books like that as well (e.g. A Song of Ice of Fire). Incidentally, how'd you feel about KSR's Mars books, if you've read them?

But I guess I forced myself to read enough Golden Age sci-fi that I developed a neurotic category for lazy... "deep worlds"? I'm looking at you and Foundation, Asimov.

So much of that stuff is a splash of human-esque characters and plot on an otherwise naked thought puzzle that I feel like it deserves its own category. I suppose it irks me less when I feel like the author did that not because they couldn't do otherwise, but because they intentionally didn't care to. Which is to say, the thought puzzle interested them more than the characters.

I feel the same about Lost. JJ Abrams doesn't give a damn about solving mysteries. He just likes creating them. Not liking him for not solving them is like not liking a dog because it wags its tail. That's a valid preference against tail wagging... but maybe not dogs for such a person?

And I really wouldn't chance a reread. I started reading it because I'd heard good things about the tech. Let good memories lie.

The lines that did me in were something to the effect of: "{Someone does a thing that makes Honor happy}. Honor felt happy because someone did a thing." (!!!)

Mars was alright. I had a lot of trouble with one of the books. Took almost a year to read because it felt like there was nothing but political infighting in it.

Foundation was actually what got me started on the "future histories" kick. The civilization is a more fleshed-out character than any human in the story. But I was eleven and didn't read any further than the original trilogy.

My favorite golden-age sci-fi would probably be Heinlein's "The Past Through Tomorrow" collection. The parallels between Elon Musk and D. D. Harriman are amusing.

I love Heilein. To me, that's when sci-fi turned the corner and stopped being pulp and started being decent literature.

I haven't read any Burroughs though. Always meaning to.

I have, but the interface by which the spoiler communicates is fairly realistic. The fact that the spoiler creates an interface to be able to communicate with humans seems a realistic take on alien-to-human communication.

Just an FYI. In Star Trek at least the warp system works like this: warp-1 is the speed of light and it then increases exponentially with warp-10 being infinite velocity.

Source: http://memory-alpha.wikia.com/wiki/Warp_factor

> it then increases exponentially with warp-10 being infinite velocity

No, no, no. That was only in the Voyager episode Threshold. It is widely regarded as one of the worst Voyager episodes, and the entire plot of that episode doesn't make any sense. There are questions of if this episode is even canon.

In any event, there are other Star Trek episodes where warp 10 is not a hard limit. All Good Things has ships traveling at Warp 13. The Kelvans modified the TOS Enterprise to travel at Warp 11. Even within Voyager, transwarp conduits allow for travel faster than whatever warp 10 would be if you disregard Threshold.

Warp 10 is not infinite velocity. It's just a line in a terribly written episode.

No, it is actually (mostly) correct. In ST:TNG they redefined the definition such that it is infinite. It was documented in the Star Trek: The Next Generation Technical Manual, which was published in 1991 and was written by the technical advisors for the series, who based it if the internal series technical bibles[1]. This was a distinct change from the original TOS which they never explained or formally retconned, but for all the series in that era it holds.

That was the standard scale used ST:TNG, ST:DS9, and ST:VOY with the notable exception of All Good Things. Obviously the point was to convey to the audience "Hey look, in the future things go much faster." Unfortunately they had originally chosen a scale that doesn't make that obvious to most viewers (it is not intuitively obvious that Warp 9.999 is substantially faster than Warp 9.99[2]). At a practical level it also very inconvenient to have a speed scale where all of the speeds share the same prefix (IOW, it is much easier for the captain to call out "Warp 9" and "Warp 12" then it is is to call out "Warp 9.99" and "Warp 9.999."

I choose to believe that the in the All Good Things timeline that once Federation started building ships that consistently exceeded 9.9 they came up with a modified scale that had better resolution and was easier to use, but that doesn't change the fact that Threshold (despite being terrible) is actually consistent with the existing source content and All Good Tings is not.

1: http://memory-alpha.wikia.com/wiki/Star_Trek:_The_Next_Gener... 2: http://memory-alpha.wikia.com/wiki/Warp_factor

The TNG technical manual set warp 10 as infinite speed, and recalibrated the scale (so that warp 9 for the Enterprise-D was far faster than warp 9 of the original enterprise.

Presumably in the alternate future in AGT they had recalibrated the scale again (probably as warp 9.975 is a mouthful, 9.9954 would be a right pain)

repeats Threshold was all a dream, Threshold was all a dream

Doesn't sound exponential to me!

Ha good point. Should have said hyperbolic growth.

If memory serves me right, Warp speeds are x^3 faster for each step. Warp 1 is 3x faster than light, Warp 2 is 27x faster, etc

It actually varies from series to series: https://en.wikipedia.org/wiki/Warp_drive#Warp_velocities

Warp speeds in Star Trek are as fast as the plot of that particular episode demands.

But... can it make the Kessel Run in less than twelve parsecs?

Star Trek's warp drive actually does not necessarily move the ship at faster-than-light-speed, but by warping space-time around the ship ("warp bubble"), so only the effective distance crossed per time is faster than SoL. I'm sure many of HN's audience are already aware of that, but it's worth noting that this might in theory even be possible: https://en.m.wikipedia.org/wiki/Alcubierre_drive

There are lots of problems with this theory, but to me it's mind blowing that it cannot be fully excluded yet. I guess we will need AI superintelligence to find out.

Charlie Stross tossed a few planet's worth of cold water on this:

http://www.antipope.org/charlie/blog-static/2007/06/the_high...

Childhood's End, Arthur C. Clarke. Space travel is sub-light speed, and specifically takes account of time dilation as an integral part of telling the story.

Now this is rumor but I understand that through CERN particles were measured to be travelling faster then light. Just sayin....

In case this isn't just a joke, they later concluded it was a measurement error caused by a fiber-optical cable that wasn't properly plugged in.

https://en.wikipedia.org/wiki/Faster-than-light_neutrino_ano...

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