Artificial gravity - a brainbug?

[Nyrath]

Obligatory Atomic Rocket reference:
http://www.projectrho.com/rocket/rocket3u.html

[Sarevok]

I have it pretty consistantly because I really don't aspire to 'hard' sci-fi. I don't aspire, really, to 'soft' sci-fi. I don't view it in those terms. If a story called for microgravity or null-G, or if I thought I could have some fun with it narratively, I'll dispense with it. Otherwise, it's convenience, a detail I don't need to worry about forgetting.

I think back to 19th century perspective whenever "hardiness" is brought up. Consider the Nautilus. It is a submarine. It is powered by sodium mined in a fashion similar to coal. Verne got the sub part right but he got infinite endurance power source wrong. He had no way to imagine the nuclear tech that gives subs their unlimited endurance. Artificial gravity is similar. We are definitely going to have spaceships just like the dream of Nautilus was achieved. But we have as much clue about where the gravity is going to come from as Verne did about electricity. Like nuclear power who knows what future invention may come. "uber realisticaly hard rotational gravity" may become as ridiculas as Vernes sodium powered engines. 500 years from now todays "realistic" scifi books featuring rotating space stations might read like another 20000 leagues under the sea.

[SirNitram]

Oh, rotational sections work.. Coriolis is tested. The problem is, well, it's not gravity, it's spinning you. The vomitting should pass quick, though the disorientation effects will always be there.

For me it has nothing to do with getting the science right. I find there's a disturbing trend that once you touch 'hard' and begin writing with the intent of it, you either strap yourself into a near-future story, or begin looking like a dunce as you extrapolate things wrong, and yet the whole time there's a sense of superiority.

I just ignore the whole issue and write the story. If I want a near-modern-Earth power, they'll have to float and strap in for exercise. If I don't, I consider the question to be up to the story, how alien I want the enviroment.

[TithonusSyndrome]

Another minor nitpick about AG that comes to mind for me is that although I don't know exactly how wank such technology is, I do know that it's more than a few decades off, centuries even, and that such an advanced piece of technology should imply even more technological advancement across the board for the spacefaring race. For instance, if the Federation can make AG, does this imply that the rest of their tech is years behind it?

[Junghalli]

Another minor nitpick about AG that comes to mind for me is that although I don't know exactly how wank such technology is, I do know that it's more than a few decades off, centuries even, and that such an advanced piece of technology should imply even more technological advancement across the board for the spacefaring race. For instance, if the Federation can make AG, does this imply that the rest of their tech is years behind it?

I'd say that's impossible to answer, really. The thing about rubber science concepts like AG and FTL is that if they ever do ever work (which is by no means certain, of course) we at this point are like sixteenth century people trying to figure out how a TV would work. The basic principles on which it operates are likely to be outside our present scientific knowledge; as far as we're concerned it's Clarketech (technology indistinguishable from magic). We have no clue how it would work, and therefore no clue what supporting technologies will be required, how difficult it will be to build, what its practical limitations will be etc.

If you're going for "hardness" with a technology like this your best bet is simply to treat it as a black box and make sure the arbitrary characteristics you give it are self-consistent.

At the same time, the ship exerts a force on the generator toward it:
<snip>
The net effect here is merely a compressive force on the boom. The ship wouldn't accelerate.

Damn, and here I thought I'd come up with a really clever idea for a hard SF reactionless drive involving a relativistically accelerated mass in a circular accelerator mounted on a retracting boom in front of a ship. Guess that wouldn't work either (heck, even if it did it probably wouldn't have been practical to give it much better than ion drive levels of thrust).

[NetKnight]

At the same time, the ship exerts a force on the generator toward it:
<snip>
The net effect here is merely a compressive force on the boom. The ship wouldn't accelerate.

Damn, and here I thought I'd come up with a really clever idea for a hard SF reactionless drive involving a relativistically accelerated mass in a circular accelerator mounted on a retracting boom in front of a ship. Guess that wouldn't work either (heck, even if it did it probably wouldn't have been practical to give it much better than ion drive levels of thrust).

So did David Weber. That's the drive used in The Path of the Fury, except it's a black hole rather then a gravity generator, and it magicly allows FTL.

As per spinning sections, I don't see why one would bother to design any ship with one. This is a ship, not a stationary, well, station. Even if one shuts down the spin when the ship is accelerating, the drive shaft will experence thrust along its major axis, and the decks will be orented the wrong way.

If one can afford to bother with spining anything on the ship (ie. if it’s not a warship), it would make far more sense to teather the ship to some large mass, like fuel tanks, and have both rotate around each other, as is depected in the manned Mars Direct missions shown here. This solves a lot of problems, most notably allowing all decks to be orented so that the direction of thrust is ‘down’.

[Paolo]

As per spinning sections, I don't see why one would bother to design any ship with one. This is a ship, not a stationary, well, station. Even if one shuts down the spin when the ship is accelerating, the drive shaft will experence thrust along its major axis, and the decks will be orented the wrong way.

The word of the day is "to secure for maneuvering." Nyrath already linked to his discussion of a "gimbled centrifuge" solution to the specific problem you raised, but you'll still want to batten down the hatches and safely secure loose items before committing to any high gee pitches, yaws and rolls.

[Zixinus]

[qoute]--the very high accelerations common in sci-fi require some piece of whizbang to cancel inertia for the crew, and once you have one of them, artificial gravity is a cinch--[/quote]

Which I might argue that enough might not be a good enough reasoning. Most realistic space drives need to only burn for a couple of seconds and spend most of the time "drifting" unless you are reading some rocketpunk novel where the ship is insanely constantly accelerating. In which case, 1G gravity is pretty incredible and darn fast considering the distances. Then you only need clever design (or designs with allot of aspirins on the side, as you wish), not artificial gravity.

Otherwise it may be better to have a rocket engine/drive (which one is correct to use anyway) that is highly effective then high thrust. High thrust, if Nyrath didn't ignore or forgot something, implies low specific impulse thus we have a space equivalent of a gas gusler. Which leads us to propellent tanks with an engine and habitat module attached to it.

On the other hand, "conservative" or variable rocket engines/drives (ala VASIMR) gets you places fast with a small but constant and effective acceleration. In-between planets thrust doesn't count that much.

For anything faster then constantly accelerating at 1 g, you might as well use a superluminal drive or warp drive.

500 years from now todays "realistic" scifi books featuring rotating space stations might read like another 20000 leagues under the sea.

While true, sci-fi writers need to sell their books while they are alive, not 500 years later.

For instance, if the Federation can make AG, does this imply that the rest of their tech is years behind it?

What bothers me, is that if you have AG what else can you do with it and what have you discovered with it? You can make artificial black holes as an energy source, for example if you can hold it in place. Or other ridiculous stuff.

[NetKnight]

As per spinning sections, I don't see why one would bother to design any ship with one. This is a ship, not a stationary, well, station. Even if one shuts down the spin when the ship is accelerating, the drive shaft will experence thrust along its major axis, and the decks will be orented the wrong way.

The word of the day is "to secure for maneuvering." Nyrath already linked to his discussion of a "gimbled centrifuge" solution to the specific problem you raised, but you'll still want to batten down the hatches and safely secure loose items before committing to any high gee pitches, yaws and rolls.

Of course such an on-board system is possible. I just question whether it’s worth the effort and expence of introducing a whole new engineering problem and dedicated class of ship, when any ship could generate AG by the method above.

In fact, there’s no real reason warships can’t use this method by tethering two ships of equal mass to each other. In peacetime anchorage, the impossibility of hiding in space precludes a surprise attack, and whenever the ships need to clear for action, they can simply detach the cable (explosively, in a matter of seconds, if need be) and correct for their now-linear vectors away from each other. In combat, adding such an extra vector is arguably a bonus, as it serves to scatter the fleet, and serve as a somewhat useful evasive tactic.

[Nyrath]

I think back to 19th century perspective whenever "hardiness" is brought up. Consider the Nautilus. It is a submarine. It is powered by sodium mined in a fashion similar to coal. Verne got the sub part right but he got infinite endurance power source wrong. He had no way to imagine the nuclear tech that gives subs their unlimited endurance.

It sounds like you were reading one of the cheap knock-off translations of Verne. According to the translation from the US Naval department, the Nautilus was powered by perfectly workable sodium/mercury batteries.
Nautilus

[NecronLord]

I wouldn't say it's a brainbug. It's a common trope, but actual brain bugs are like... Jefferies tubes everywhere in UFP starships, for instance.

[Nyrath]

Damn, and here I thought I'd come up with a really clever idea for a hard SF reactionless drive involving a relativistically accelerated mass in a circular accelerator mounted on a retracting boom in front of a ship.

Well, the problem is that it is more or less impossible to use the term "hard SF" in the same sentence as "reactionless drive." Such drives violate the law of conservation of momentum.

And even if you postulate their existence, they have unintended consequences

[RedImperator]

--the very high accelerations common in sci-fi require some piece of whizbang to cancel inertia for the crew, and once you have one of them, artificial gravity is a cinch--

Which I might argue that enough might not be a good enough reasoning. Most realistic space drives...

...are largely absent from scifi, especially media scifi. Drives with multiple hundreds or thousands of g's acceleration are common, and with them, you do need inertial compensation. If you're staying hard and using realistic engines, you aren't going to have artificial gravity anyway.

[Darth Wong]

And for some reason, this isn't uncommon in SF literature. Think about this for a moment. On TV and in movies, artificial gravity saves on production costs, but what good is it in text?

It reminds the audience of how "advanced" the sci-fi civilization in question is. In some cases, it can also be used as a cheap plot device. But another factor is that a lot of sci-fi authors have visual imagery in their minds when they write, and that visual imagery tends to be based on the sci-fi movies they've seen.

[Junghalli]

As per spinning sections, I don't see why one would bother to design any ship with one. This is a ship, not a stationary, well, station. Even if one shuts down the spin when the ship is accelerating, the drive shaft will experence thrust along its major axis, and the decks will be orented the wrong way.

It works better for ships that have low-fractional G accelerations (i.e. most realistic designs). Take something with the same acceleration as a Daedalus spacecraft (.33 m/s^2). Under thrust you'd have 1 G (or maybe .3-5 G) of centrifugal gravity in one direction and .033 G in the other direction. I'm not sure how annoying the .033 G in the wrong direction would be, but it probably wouldn't be much worse than feeling like you were on a gently sloping hill.

It sounds like you were reading one of the cheap knock-off translations of Verne. According to the translation from the US Naval department, the Nautilus was powered by perfectly workable sodium/mercury batteries.

He has a good general point though. Every technological generation may incorporate a certain amount of what to the previous one would have been Clarketech (technology indistinguishable from magic). To somebody from the nineteenth century a nuclear reactor would have been Clarketech: the basic principles on which it operates would have been totally unknown to science at the time (radioactivity was only discovered in 1896).

[RedImperator]

He has a good general point though. Every technological generation may incorporate a certain amount of what to the previous one would have been Clarketech (technology indistinguishable from magic). To somebody from the nineteenth century a nuclear reactor would have been Clarketech: the basic principles on which it operates would have been totally unknown to science at the time (radioactivity was only discovered in 1896).

Zixinus had a good point too: by the time science advances to the point the sci-fi writer's attempt at accuracy becomes dated, the sci-fi writer is dead (or at least, he's already made whatever he was going to make off his advance and residuals). The exceptions are writers who try to go hard and bleeding edge, seizing on the hottest new hypothesis for their plots--ZPE or quantum whatsit or atomic Leprechauns or whatever--and then six months after publication, a follow-up paper completely debunks ZPE or quantum whatsit or atomic Leprechauns. But that's the risk you take trying to write bleeding edge. If you stick to solid proven stuff like lasers and fission, with some reasonable extrapolation, you're fairly safe.

[Coyote]

Two things can be done to take the 'golly-gee-whillikers' out of AG. One might be to have a spinning ring inside, the purpose of which is really little more than to give the crew a couple of hours of gravity a day for fitness purposes-- jog around the inside as it spins, with a virtual-reality visor on to give you the look of running on a real track with an actual horizon to avoid the disorientation. Having the crew sleep there might also work.

Another would be to have some sort of expensive "wow" technology that, again, is very expensive and hard to do, and is only used in one area of the ship (maybe even for limited times), again, most likely for crew health & fitness.

Limited use stuff like that might allow a "hard" SF setting to retain its credentials.

[Junghalli]

Zixinus had a good point too: by the time science advances to the point the sci-fi writer's attempt at accuracy becomes dated, the sci-fi writer is dead (or at least, he's already made whatever he was going to make off his advance and residuals). <snip> If you stick to solid proven stuff like lasers and fission, with some reasonable extrapolation, you're fairly safe.

Oh, I agree. I was more thinking that it makes a few isolated rubber techs (like AG, FTL, Langston Fields) in an otherwise hard setting less principle-breaking, to me anyway. I can just accept that "yeah, they've learned a trick or two we don't know" and move on.

Two things can be done to take the 'golly-gee-whillikers' out of AG. One might be to have a spinning ring inside, the purpose of which is really little more than to give the crew a couple of hours of gravity a day for fitness purposes-- jog around the inside as it spins, with a virtual-reality visor on to give you the look of running on a real track with an actual horizon to avoid the disorientation. Having the crew sleep there might also work.

A ring like that would probably have to be quite large to simulate Earth gravity and avoid coriolis effects that would make people sick. Probably large enough that you might as well make it a full-on habitat ring.

[Luzifer's right hand]

While true, sci-fi writers need to sell their books while they are alive, not 500 years later.

Someone presumably writes SF because the person enjoys doing so, if you are good writer and able to sell books you can earn much more in other genres or even as a translator if you are non-Englishwriting.

[Junghalli]

Someone presumably writes SF because the person enjoys doing so, if you are good writer and able to sell books you can earn much more in other genres or even as a translator if you are non-Englishwriting.

True, I put a lot of work into my own uni that I know very well probably won't translate into a cent of extra profit if/when I publish anything.

[Ziggy Stardust]

Science fiction is literature just like any other. If a story is good and includes a brainbug like artificial gravity, why the fuck does it matter? The only time it really makes a big difference if they get the science wrong is if the story itself isn't any good, and in that case there are better things to bitch about then whether or not the character walked or floated. I think a dogmatic dedication to the concept of "hard sci-fi" is ridiculously narrow-minded.

[Zixinus]

Someone presumably writes SF because the person enjoys doing so, if you are good writer and able to sell books you can earn much more in other genres or even as a translator if you are non-Englishwriting.

So what, sci-fi writers should write for free now? Even if the person enjoys doing it, it doesn't mean he doesn't expect to get paid for it.

[Luzifer's right hand]

So what, sci-fi writers should write for free now? Even if the person enjoys doing it, it doesn't mean he doesn't expect to get paid for it.

Someone who starts writing can't expect to ever get any money, especially if you write stuff like SF. I only know that stats for the germanspeaking market which is the third biggest market in the world, less than 100 writers can live from what they earn by writing.
It's rather likely that someone will never earn anything with writing or even lose money as you need to spend losts and lots of hours to write a book.
If someone wants to try to write stuff which is not dated in 500 years(although I think thats completely impossible when you write SF) why not.

[Admiral Valdemar]

If you're writing for money, you're doing it wrong.

[RedImperator]

Science fiction is literature just like any other. If a story is good and includes a brainbug like artificial gravity, why the fuck does it matter? The only time it really makes a big difference if they get the science wrong is if the story itself isn't any good, and in that case there are better things to bitch about then whether or not the character walked or floated.

I don't know about you, but when I'm reading a story and the writer gets some fact disastrously wrong, that it and of itself can ruin it by breaking suspension of disbelief. If I can't believe in the setting, then I can't believe in the characters or the plot, either.

Artificial gravity (and FTL) are usually treated as exceptions because people are used to them (and in the case of FTL, many allegorical SF stories aren't possible), but otherwise, I don't see why science fictions writers deserve a free pass. If you're too lazy to bother with your homework, why should I bother reading your story? Imagine the author of a piece of historical fiction where George Washington defeated the Mongols at the Alamo trying to defend his work by saying "Well, if the story is good, who cares if the facts are wrong?"

I think a dogmatic dedication to the concept of "hard sci-fi" is ridiculously narrow-minded.

Yeah, as opposed to a personal preference or something like that.