Technology Limits in Hard Science Fiction

Gravity! The artificial gravity of space opera would be pretty hard to do technologically. I've set all my space stations spinning but what about the shuttle that runs between planet a and planet b. It is an ordinary transport run but how do I not squish the passengers.

Deceleration on spaceships, which is always the hard part once you've covered every other concern

A good place for answers to this question is the SFIA channel on youtube. Isaac Arthur covers megastructures, space colonization, FTL drives, etc etc etc etc. There's probably a couple hundred hours worth of very insightful analysis. A small sampling to answer your question might include: the impracticality of Bussard ramjets, heat dispersal issues in ecumenopolises (ecumenopoli?), the real material limits for building megastructures, various SF types of FTL and what current physics says about them, issues surrounding A.I, the singularity, transhumanism...

Very easy to lose a couple of days in there.

I guess I disagree that hard sci-fi has to respect our current understanding of physics. I still love a good time-travel story, as impossible as that apparently is. What interests me more in sci-fi are the limits of biology. We know so little about that compared to our knowledge of physics. Lots to imagine and explore, with few technological limits so far.

nickj47 said:

I guess I disagree that hard sci-fi has to respect our current understanding of physics. I still love a good time-travel story, as impossible as that apparently is. What interests me more in sci-fi are the limits of biology. We know so little about that compared to our knowledge of physics. Lots to imagine and explore, with few technological limits so far.

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It's a matter of personal preference for both the reader and writer. The "hardness" of sci-fi is really a variable scale, not an absolute, so a story that goes for realism except allows for FTL travel can still qualify as hard. But writing work without that sort of cheat can be an interesting challenge.

themindstream said:

[The hardness of a story is] a matter of personal preference for both the reader and writer. The "hardness" of sci-fi is really a variable scale, not an absolute, so a story that goes for realism except allows for FTL travel can still qualify as hard.

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Good point.

I think this is because SCIENCE is not an absolute. Theories are considered true in science because they fit the facts as observed by people or through peoples' machines. One new fact can disprove an entire theory.

(Well, supposedly. Actually, scientists are very reluctant to discard a theory which works for lots of cases. It usually takes something that, like a crack in a dam, explodes the dam/theory. Physicist Thomas Kuhn wrote an entire book describing how theories get made and discarded: The Structure of Scientific Revolutions.)

So tomorrow someone might come up with a convincing theory of how we could travel faster than light. I say convincing because if I recall rightly there are two or three FTL theories, just none (yet) convincing enough.

Heinlein (I THINK it was) said that a good sci-fi story imagined no more than one impossible thing. I've taken that as a good technique in writing my stories: one breakthrough fact/machine/process but everything else rigorously true to current theories. Or maybe only two or three breakthroughs. Certainly not a whole crowd of them.

My guess is that most of us want an SF story which has likable (or interesting) BELIEVABLE people doing interesting things. And the hardest of SF without that stays on the booksellers' shelves.

From what I can tell, “Hard Science Fiction” is also known as Just Science Fiction, and generally it means to readers books about boy science stuff not icky girl stuff like anthropology or archaeology or political science.

If if you can’t tell from my tone, I am saying there’s not really such a thing as “hard science fiction” it doesn’t exist. The head editor of Analog Magazine lists Flowers for Algernon as his preferred prime example of hard science fiction, and no one seems particularly concerned about speed of light or pure science accuracy, in that story.

I've written hard sci-fi, I guess, with one novel and many short stories, including stuff in Analog, so I am not an absolute authority, but I know a little bit.

Hard science fiction is just just science fiction being marketed to an audience that includes scientists and people who play scientists on TV, so to speak.

(I have written scientifically accurate stories based on new research and been raked over the coals by “scientist” reviewers, so maybe include citations if that bothers you. Science is a wild and woolly thing and everyone is very certain they are right.)

My feeling is that hard SF is part of a continuum, with science fantasy (a la Star Wars) towards the other end. At the hard SF end, you try to stay consistent with the real universe as much as you can; at the other end, you aren't even concerned about the concept of planets being in different star systems.

Dennis E. Taylor said:

My feeling is that hard SF is part of a continuum, with science fantasy (a la Star Wars) towards the other end. At the hard SF end, you try to stay consistent with the real universe as much as you can; at the other end, you aren't even concerned about the concept of planets being in different star systems.

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This is my belief as well. Hard sci-fi is fiction that features a plausible scientific concept as a strong story element. The rest of the science presented in the story holds up. Soft sci-fi contains science fiction elements, but the science is weak.

As a side note, I don't understand why FLT is so often considered implausible, as real-work scientists discuss how to travel faster than moving in a straight line through three-dimensional space. We call it "faster than light" but simply mean "traveling a different path than we generally witness light taking".

aspirit said:

As a side note, I don't understand why FLT is so often considered implausible, as real-work scientists discuss how to travel faster than moving in a straight line through three-dimensional space. We call it "faster than light" but simply mean "traveling a different path than we generally witness light taking".

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Yes, it’s interesting to listen to some people talking about how it’s impossible while other people are talking about how it could be done. Same with time travel. What they really mean is it’s impossible according to this theory.

Ummm, re FTL travel: Star Trek actually had a viable theory with Warp Drive even though it is as yet unachievable. The concepts of warping space-time and wormholes don't necessarily defy physics.

The TauZero folks are on it.

Our understanding of the universe constantly shifts; stuff that was implausible as recently as a decade now might be today's current or future science. FTL travel is just one of the easier things to pick on as an example as our current understanding maintains that it's impossible yet without it a whole lot of sci-fi wouldn't work.

I was working through some time dilation stuff for my WIP, and I very quickly realized that FTL travel and FTL communication would imply that time travel was possible. I asked my brother about it (he's a physicist), and his little eyes lit up. "That's the thing," he said. "If FTL is possible, everything breaks." (He has absolutely no trouble enjoying SF that includes FTL travel. Or time travel, for that matter.)

I can't think about it too much. If I try to make it consistent in my head, I sort of panic. So I include FTL travel, throw around terms like "field generation," and go from there. (And yes, I've had people tell me it's not true hard SF if I posit FTL travel, but that specific label isn't important to me.)

Heh, I tend to view FTL as more trouble than it's worth. Also secretly hate it (don't get mad, that's just me and I've read about a million SF novels I've loved that feature it). But then I also find it snobbish to declare well-researched plausible examples of it 'soft' SF. Good points here about finding ways around it as opposed to simply upping the speed limit, plus I think it can be (potentially) wrong-headed to work simply from what we know know, and assume by the time we have spaceships & shit we won't know more.

badducky said:

From what I can tell, “Hard Science Fiction” is also known as Just Science Fiction, and generally it means to readers books about boy science stuff not icky girl stuff like anthropology or archaeology or political science.

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So much yes.

SciFi is an inherently optimistic genre because it believes that humanity will eventually solve these technological challenges. In my writing I like to look at current tech trends then project them forward.

If we as a species can manage to not exterminate our selves I believe we will find a way to make interstellar travel possible.

indianroads said:

SciFi is an inherently optimistic genre because it believes that humanity will eventually solve these technological challenges.

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SciFi is an inherently optimistic genre because it believes humanity will survive all the horrors of the present day.

badducky said:

The head editor of Analog Magazine lists Flowers for Algernon as his preferred prime example of hard science fiction, and no one seems particularly concerned about speed of light or pure science accuracy, in that story.

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Which is only because "Flowers for Algeron" doesn't involve space travel or any similar physically-implausible gadgetry. It is a science-fiction story in the same sense that Orwell's 1984 or Burgess's A Clockwork Orange are science-fiction. If you want to consider "hard" SF that involves space travel, much of Arthur C. Clarke's best work fits that paradigm.

caw

My personal line for hard sf is if I can plausibly believe that with future advances and discoveries, such things could exist. If it's already disproved by current knowledge (example: firey space explosions) then it's not hard.

Mathematically, FTL travel is in the same category to me as negative distance.

lizmonster said:

SciFi is an inherently optimistic genre because it believes humanity will survive all the horrors of the present day.

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I agree, even dystopian SciFi can be optimistic.

SciFi is an inherently optimistic genre because it believes we will survive the present day to be destroyed by all sorts of new, improved horrors.

One of the reasons I don't worry about or even accept the idea of "hard" science fiction is precisely because of what Arthur C Clarke himself said: Any sufficiently advanced technology is indistinguishable from magic.

Maybe we humans don't know enough to travel faster than light right now. But so what? 500 years ago, nobody knew how to travel faster than wind or gravity could propel you. And if 2 people had working cell phones back in the 1600s, they'd likely end up burned at the stake for being witches.

So to me, "Hard science fiction" is just saying "okay, let's set our story sometime in the future... but pretend we don't learn anything that we don't know right now". And that just doesn't make any sense to me at all, given the advances I've seen just in my lifetime alone.

So I guess what I'm saying is that the term seems to expect me to do something that I'm just not willing or able to do: forget that our knowledge of science, and what can be done, advances every day, and that by it's very nature science fiction is a speculation on what may be coming eventually.

By the way, I'm old enough to remember watching the first men walk on the moon. I also went to Huntsville and saw the space shuttle before it ever flew... and I've also seen it retired. What do you think a couple of bicycle-repairing brothers from Kitty hawk North Carolina would think of that?

OldHat63 said:

By the way, I'm old enough to remember watching the first men walk on the moon.

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Oh, hey, me too! I also saw Skylab launch (the unmanned part). Last launch I watched was a livestream of Antares in 2014. Not that I'm superstitious, but don't watch launches live anymore.

The thing about FTL travel that isn't true for the space shuttle or the airplane is that it appears to actually break physics. Personally I find this amazingly cool, even if it means I have to ignore some paradoxes when I'm worldbuilding. As an author, I'm OK with people pointing to my FTL treatment and saying "Not hard SF!" Far worse things have been said.

To me, hard science fiction can violate any particular rule of physics or other science, as long as it doesn't ignore their existence. Have FTL, but don't ignore the existence of relativity. Have artificial gravity, but don't ignore how that's in violation of our current understanding of things. If your fighters can bank in space, have a throwaway line about how it shouldn't be possible but is. It's like any other art. It's okay to violate the norms, but you need to know what they are before you do.