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The starship 'Exciting Undertaking' has set off on a brand new five and a bit year expedition to explore the galaxy. To make such a starship possible, an artificial gravity generator had to be invented. The first model was delivered and tested and worked just fine, thank you.

When Exciting Undertaking is launched, at what level should we set the artificial gravity generation? Sure humans are used to 1$g$, but is that really the best gravity force to set it at?

Details:

  • Only humans are on board these vessels.
  • The gravity generator can be controlled differently in different spaces on the ship, as necessary. Gravity is provided by continuous plating, so each separate room or corridor must be kept at a constant gravity level.
  • Gravity can be controlled to 0.01$g$ precision.
  • The rate of change of the gravity generator is relatively slow due to the desire to limit structural stresses on the ship. Assume a rate of change of 0.1$g$ per minute.
  • The gravity generator is a power hog, but with an anti-matter powered reactor, the cost of running the generators at any setting is not a major concern.
kingledion
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    How finely grained can the artificial gravity be controlled? If it could be controlled with enough precision it could be used to disable boarders and make moving cargo extremely easy. Is the force vector always along the normal of the deck or can it be arbitrarily oriented? Can it be reconfigured on the fly? How rapidly can it be reconfigured? How do you define best? – sphennings Jan 02 '18 at 14:16
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    Please define your "best". Also, if we are supposed to take into account other species, you probably should list them and tell us what are they used to and what are their "borders" - as we only have reliable data on humans. – Mołot Jan 02 '18 at 14:20
  • @sphennings As for best, whatever helps the ship most effectively complete its mission is the best. For details of missions, see here. – kingledion Jan 02 '18 at 14:39
  • What's the resoultion/variance in the artificial gravity control? If I'm in 1g what is the maximum and minimum g that can be achieved 1m away from my position? Can you provide enough of an overview of the mission in the question so that the question doesn't rely on external links? – sphennings Jan 02 '18 at 14:47
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    Does the gravity generator require different amounts of power at different settings? For example, do higher gravity settings require more power? Does maintaining different settings across different parts of the ship require more power than having a uniform gravity across the entire ship? – F1Krazy Jan 02 '18 at 14:49
  • Shape of the ship, orientation of walls and floors? Cylindrical? Regular flat and parallel floors? Energy consumption of that generator? Possible shape of the generator (point, rod, flat plane, curved)? – Karl Jan 02 '18 at 14:57
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    Is cost effectiveness a concern? Can the gravity generator create opposing forces to counteract the stresses that it creates? – sphennings Jan 02 '18 at 15:06
  • Differing and changing gravitational loading would, I am sure, be like the changing stress levels due to heating and cooling, especially differential heating and cooling. The design engineers would have to take this into consideration, and design constraints altered to accommodate these changing stress levels. – Justin Thyme Jan 02 '18 at 15:50
  • Hey, HERE'S a concept for you. Gravity paint. Just paint it on the surface of whatever you want to have excessive gravity. Adjust the gravity by changing some component of the electromagnetic field, like changing the light frequency will change the color of paint. Dial up the gravity to the level you want. or turn it off with a flick of the switch. – Justin Thyme Jan 02 '18 at 16:09
  • @JustinThyme Jack Brennan in Larry Niven's [Protector](https://en.m.wikipedia.org/wiki/Protector(novel))_ did something similar by plating things with neutronium. – Spencer Jan 02 '18 at 23:50
  • @Spencer I can envision it being done by spraying bosons and not entire atoms. Sort of like spraying electrons from a filament. Make them continuously in a cyclotron, and deposit them before they decay. – Justin Thyme Jan 03 '18 at 00:54
  • How have I not seen this question before now?!? – Joe Bloggs Aug 28 '18 at 06:29

4 Answers4

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When you say 'Best' do you mean 'best for the crew', 'best for operation of the ship', 'best for maximum use of space', or 'best for the author, in case the book is made into a film'?

Star Trek had 'normal' artificial gravity simply because it was much easier to film the series in 'normal' gravity.

But as we now know from ISS, a lack of gravity is really, really useful for utilizing every available bit of space in the ship. With no 'up' or 'down', and no 'falling out of cupboards', then storage lockers can be put on all of the walls, complete surround storage. So in terms of space utilization efficiency, no gravity is best.

But in terms of housekeeping, when suspended particles never move, except in the air flow, keeping the central room space empty requires a bit of gravity to attract everything to a surface. Thus, for housekeeping it makes sense to have a surround gravity. That is, every surface in the space has some gravitational attraction sufficient to keep things on the surface.

In terms of human health, are the inhabitants ever expected to return on-planet? If they are permanent spacers, then humans can do just fine in point 2 or point 3 gravity. Mars, for instance, would need no gravity enhancement in the living spaces.

But since inertia is always the same with or without gravity, the lower the gravity the slower the spacemen could move. Accelerating too fast means that, when they hit solid wall, they do so with a painful thump. So they would move very slowly to limit acceleration, and therefore minimize inertia. Having all of the outside surfaces be the gravitational attraction would perhaps ease the problem, because there would always be 'counter gravitational forces' in every direction.

However, gyms and such exercise and sports spaces would definitely want high 'up-down' gravitational fields. When jogging, for instance, you want sufficient gravity to allow high acceleration without inertial run-away, and you want the track to be 'down'. You want sufficient gravity to allow good friction between boot and tack surface.

To maximize sleeping surface, a round tube where bunks would be placed all around the outside, with minimal gravity around the outside to keep the occupants from drifting. In naval ships,the bunks are stacked four and five high to maximize sleeping space. Imagine if they could utilize top and bottom surfaces? That is, crew members face each other when sleeping.

But eating quarters and dining rooms? Definitely things work better when the table is down and your mouth is up. Makes food much easier to cut and stab.

Office-type quarters would require a constant up-down gravity field. Typing is rather difficult when every key press sends the typist backwards. Writing is hard when an over-emphatic pen stroke sends the writer flying off to the side. Fidgeting in the chair can launch one into an unintended trajectory. And squirming in a chair? Forget it, unless something is 'sticking' you to it.

However, I can foresee that perhaps the propulsion system would work best in no gravity. 'Containment vessels' are much easier to control when there is no gravity pulling on the object to be contained. Place the substance in the general area, it does not move. Turn on the containment field around it. No need for supports before the containment field is turned on.

So the bottom line. If you are really after 'best', and the technology allows it, different gravity on different surfaces in different parts of the ship would be 'best overall'. Say in the storage areas, no gravity; in the gyms, high gravity on the playing surface (perhaps 'dial-a-gravity' to increase the intensity of the workout); in sleeping quarters, mild gravity around the walls; in transit hallways, no gravity but lots of handholds, padding, and inertial shock absorbers at the ends; in the dining room, low gravity on the table; and in office-type areas, low gravity in an up-down orientation to allow paper to remain still in slight breezes, and people to stay sitting even while fidgeting.

And how about 'dial-a-gravity' special surfaces throughout the ship for housekeeping? Turn them up, way up, all the garbage gets attracted to them. Just wipe the surface off, and return to normal gravity situation. No more clutter, no more dust.

kingledion
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Justin Thyme
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    Okay, my last point just created in me the image of 'cleaner maintenance bots' traveling throughout the ship, with a high gravitational field around them, drawing everything into them. Like a vacuum cleaner on steroids. – Justin Thyme Jan 02 '18 at 15:58
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    If they are permanent spacers, then humans can do just fine in point 2 or point 3 gravity.[1] Citation needed. Given the detrimental health effects observed on modern astronauts from mere weeks or months in micro-gravity, it seems like our bodies were designed to work under 1g, and don't tolerate large deviations from that particularly well. I'd bet that unless the gravity is set at or near 1g, your crew would start experiencing undesirable side effects. – HopelessN00b Jan 02 '18 at 20:16
  • @ HopelessN00b These side effects are only an issue if you want to return to a high gravity environment. And they can be countered by exercising in a high gravity gym. There are no functions of the human body that are dependent on gravity, they tend to just atrophy in the absence of it. By your own reference, the lack of day-night cycling and work stress are the major contributors to ongoing health issues. – Justin Thyme Jan 02 '18 at 21:16
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    Losing 1% of your bone mass a month, and degenerative weakening of your muscles, including your heart muscle, don't sound like issues that only matter in normal gravity. Maybe osteoporosis and muscle atrophy are more tolerable in micro-gravity, but I suspect that cardiovascular degeneration is going to be a big problem for people who want to continue living, even if they stay in micro-gravity. Of course, one of the other side effects is kidney stones, so maybe they'd rather have their hearts give out quickly than spend years passing kidney stones in micro-gravity. – HopelessN00b Jan 02 '18 at 21:26
  • @HopelessN00b You don't need muscle mass or bone density if you are permanently in low-g. Neither one is life-threatening. You only need them when you return to g. Some have hypothesized that on low-g generational ships, bone would be eventually replaced by cartilage over several generations. However, in a generational ship, traveling from one end to another, even in low g, using hand-holds would ensure muscle mass. It's not a viable exercise routine on ISS because there just isn't the clear space available. Like mall walking vs going from the couch to the fridge. – Justin Thyme Jan 02 '18 at 21:56
  • @HopelessN00b NASA has found out long ago these effects can be fought rather effectively with (daily) gymnastics even in zero g, and even with the cruddy sports equipment on present day space flight. – Karl Jan 02 '18 at 22:00
  • Some of the above can be done far more cheaply with suction pads and magnetic/electrostatic attraction, than through using gravity generators. Housekeeping bots, for instance, an static charge will be far more efficient at attracting dust than gravity; similarly, using suction pads on the base of your keyboard allows you to use it in any orientation, without the need for additional power expenditure. – nzaman Jan 02 '18 at 23:42
  • @ nzaman Suction pads and Velcro do not get around Newtons' Laws - for every action, there is an equal and opposite reaction. Press on a key, you go back. On ISS, one solution is for the typist to be Velcroed to the anchored chair. – Justin Thyme Jan 03 '18 at 00:48
  • @JustinThyme, some of the effects are an issue no matter what. For example: loss of immune function -- and exercise doesn't counteract it. – Mark Jan 03 '18 at 03:24
  • @Mark If you are on a generation ship, loss of immune function is perhaps a good thing. No diseases if there are no viruses or bacteria, and over-reactive immune systems would then be the biggest hazard. There are so many auto-immune diseases we DON'T want. – Justin Thyme Jan 03 '18 at 05:26
  • "Some of the above can be done far more cheaply with suction pads and magnetic/electrostatic attraction, than through using gravity generators."

    That depends quite a lot on how this imaginary gravity generator actually works, doesn't it?

     – GrandOpener Jan 03 '18 at 08:40
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    @JustinThyme, the human body is a carrier for a huge number of bacteria -- by cell count, a human can be considered a multi-species bacterial colony with a eukaryotic life form wrapped around it. Some of these bacteria are essential for life, most are neutral, some are harmful, and all are kept in check by the immune system. Even ignoring the possibility of mutation, a loss of immune function is going to result in long-term problems. – Mark Jan 03 '18 at 09:39
  • @HopelessN00b "it seems like our bodies were designed to work under 1g, (...)" Designed? Our bodies were designed? That certainly requires a [Citation needed]! – xDaizu Jan 03 '18 at 11:24
  • @Mark There is no conclusive evidence as th weather the immunological effects are due to weightlessness or some other factor caused n]by isolation. No astronaut is sent into space with any communicable disease, and they are kept in isolation before launch. Perhaps it is something about the environment other than weightlessness. – Justin Thyme Jan 03 '18 at 12:50
  • Unfortunately spinal fluid is regulated by gravity, so many people in micro gravity experience space blindness, which is the result of spinal fluid pressing against certain nerves in your head do to increased pressure from lack of gravity. Unless you want to be constantly draining spinal fluid from your astronauts (which is a very bad idea) then you should set limits for how long anyone can stay in zero g. – Clay Deitas Aug 28 '18 at 04:04
  • @Clay Deitas ''Alperin says that learning about the causes of VIIP is a necessary step in finding countermeasures to combat it. ' from https://newatlas.com/blurry-vision-cause-astronauts-spinal-fluid/46667/ Apparently NASA does not consider it an unsolvable problem. – Justin Thyme Aug 28 '18 at 15:30
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Justin's on the right track, let's add to it.

  • With perhaps a few exceptions, variation needs to be minimized or you'll need "gravity locks" (the equivalent of "air locks") all over the ship to help people transition from one gravity to another. If you don't, the stress on the cardiovascular system would be substantial.

  • Crew members destined to go planet bound for anything other than minutes (or maybe an hour or two, depending on how friendly the environment is predicted to be) would need to "decompress" to that gravity level. In other words, if the ship operates at 0.8g all the time, but the planet the away team is about to visit (a completely unknown planet, you might encounter anything) is 1.2g, then your away team would need to live in an increasing gravity for a period of time to ensure they were ready physically to deal with any contingency on the planet. Otherwise (in this example), they risk sitting duck status because they're too weak to push against the planet's gravity.

Having said that, let's think about what would be "best" for the crew.

  • Moving things around in 0g is a lot more painful than people might think. You still need some way to move around objects of heavier mass than yourself. Under normal conditions you'd use a pallet jack to compensate for the difference, but there's nowhere to put the wheels in 0g. That means thrusters in a 3D environment. Very chaotic.

  • Other than exercise, I can't think of any reason why you'd want heavier "g" anywhere in the ship. But the gym is a good place for it as a bit more gravity will help with the cardio.

  • Finally, you want an improvement in performance without a loss of precision (see 0g discussion, above).

I'm going to conclude (and yes, I'm pulling this judgement out of my left ear), that you want 0.9g everywhere on the ship other than specific locations, like the gym. This improves the efficiency of personal strength without losing basic traction and leverage.

  • Medical may want 0.8g to relieve stress on the heart. However, medical is the one place where you'll want different rooms to have completely reconfigurable "g" values. It will have the greatest number of reasons to vary it.

  • The gym, perhaps two or three rooms, 1.1g, 1.4g, 1.8g. Your hulking red shirts will be in the 1.8g room lifting weights all the time.

Keeping all the rooms (save a few) minimizes stresses on the ship and also minimizes the potential for harm if emergency maneuvers are required. A sharp turn in that 1.8g gym has a greater potential for harm than a sharp turn in the 0.6g surgery.

Summary: while specific room requirements may vary, and you'll need gradients to move between the rooms unless the delta-g is low, my belief is that 0.9g is the "best" overall value to improve strength without losing traction and leverage.

Brythan
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JBH
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    That "decompression" scheme sounds wild. Astronauts just walked out of the space shuttle after months on the ISS at zero g. Visiting a planet with 1.4g needs a lot of beforehand exercise. And humans just don't work and walk safely at 1.8g. You'd have to design a new brand. – Karl Jan 02 '18 at 19:47
  • @Karl, I thought about spacewalking, but there was nothing requiring strength and leverage (well, almost nothing) that wasn't in a completely controlled environment. How would the human body react if you beamed down to (for convenience) a 2g planet and suddenly found yourself running for your life? You'd feel twice as heavy. Granted, you should be in great shape to begin with, but it would have a toll. That's avoided (or, at least, ameliorated) with the "decompression" time acclimating to the planetary gravity. Seemed like something cool to add to a book 'cause no one's ever cared before. – JBH Jan 02 '18 at 20:58
  • I strongly doubt that a human can adapt to 2g. A fifty kilogram person cannot just carry fifty extra kilograms. With 20kg worth of extra muscles perhaps, but then you're at 2x70=140kg total. Not to mention your circulation etc. Otoh 1.4 should be unproblematic for a healthy, sportive individual, although I'd definitely demand extra pay. You don't want those astronauts to just be there, but do actual work, right? – Karl Jan 02 '18 at 21:17
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    @Karl The returning astronauts from the space shuttle DID go through a 'regravitation' procedure. The Russians seem much more open to showing this to the public than the Americans do. But there is a 'return-to-earth' protocol process that astronauts go through. It involves bed rest and remaining seated. I really like the foresight of the suggestion. – Justin Thyme Jan 02 '18 at 21:33
  • @JustinThyme Yes. That's for science (every astronaut is a guinea pig), and for safety, because the change from zero to ten meters per square second is quite extreme. A change from 0.8g to 1.4g is hardly worth mentioning, in comparision. Everything is a bit heavier vs. *i only used visual orientation for six months". I'm saying nothing against giving those astronauts 1.4g in the gym when preparing for the landing. – Karl Jan 02 '18 at 21:43
  • I thought about the sudden maneuvers bit, but then re-read the question. This is a transport, not a fighter. Like an ocean-going tanker vs a corvette. Sudden tight turns would not be possible, let alone expected. The power to do so would be enormous. I really like your regravitation period, which would be a really good reason for maintaining a relatively stable gravity throughout. – Justin Thyme Jan 02 '18 at 21:47
  • ctd But i would suggest that cargo holds would be at the lowest g possible. Things don't fall in zero g. Your hand truck illustration is germane. On earth, when you use a hand truck, the pull of gravity stops the load from continuing when you get to the right height. In zero g, it just keeps going until something stops it. – Justin Thyme Jan 02 '18 at 21:47
  • I think higher gravitation in the gym is very dangerous in case of any sport accident. Every fall is a broken wrist or torn ligament. – Karl Jan 02 '18 at 21:53
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    @Karl, the comments are as fun as actually answering the qeustion. Working out the gazintas and gazoutas of how something that doesn't exist might work is fun, and it illustrates how nearly impossible it is for just one person to solve almost any problem in today's complex world. You insight into the gym is good. A 1.1 or 1.2g environment would help, but the 1.4 would have a high liklihood of substantial injury (just as powerlifters today do). – JBH Jan 02 '18 at 22:24
  • @JBH I thought it was 'gazintas' and 'gosoutas'. – Justin Thyme Jan 02 '18 at 22:29
  • @JustinThyme, I make no claim whatsoever to good spelling! None, I tell you! None! :-) – JBH Jan 02 '18 at 22:31
  • @JBH I'd prefer 0.8g in the gym. Definitely safer, makes no difference for using most exercise equipment (just need some 20% larger weights), and probably a bit more fun on some other exercises. – Karl Jan 02 '18 at 22:37
  • Reading about your gravity locks, I can't help but wonder whether quickly going from high g to low g would feel like falling (after all 0g is called free fall for a reason), and would require quite a lot of training to avoid upsetting your stomach on a regular basis. – MvG Jan 03 '18 at 02:36
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The best setting for gravity plates onboard the Exciting Undertaking would be a constant 99 g. The gravity plates capable such strong gravity would be installed in the ceiling of all habitable work spaces accessed by the human crew. The benefit lies in maximizing travel time across interstellar space. There will be a second set of gravity plates installed in the floors of all work spaces.

One of the less commented upon problems of interstellar space travel is the long acceleration times required to reach sufficiently high velocities to travel between stars within modest fractions of a human lifetime. Accelerating close to lightspeed provides the necessary velocity and comes with additional bonus of relativistic time dilation.

Obviously a mighty space craft like the Exciting Undertaking if it is powered by antimatter reactors will have no difficulty in being equipped with a propulsion system, doubtless powered by antimatter, capable of accelerations of up to one hundred gravities (100 g). At an acceleration of 100 g the Exciting Undertaking will attain near-lightspeed in roughly four days.

This will give it a brief acceleration phase, push it to sufficiently close to lightspeed to provide a reasonable amount of relativistic time dilation, and thereafter its antimatter engines will generate a constant 1 g acceleration up until it reaches the midpoint of its journey when it commence a long 1 g phase. Once the Exciting Undertaking is within two light days of its destination it can once more engage in a 100 g deceleration phase.

The 99 g gravity plates will compensate for excessive "gravity" in the acceleration and deceleration phases. The human crew will experience an apparent internal gravity of a comfortable 1 g during those acceleration and deceleration phases.

Please starships capable of constant 1 g acceleration will take of the order of one year plus to attain similar amounts of close to lightspeed velocities. The Exciting Undertaking, by contrast, using its 99 g gravity plates as acceleration compensators will do so in only four days. This will reduce its rest frame travel times by about one year. It will also spend more time experiencing relativistic time dilation. The human crew will have shorter travel times.

It is noted, more in sorrow than anger, that the OP has not specified whether the Exciting Undertaking is capable of faster-than-light travel. If it is a FTL vessel, then this cunning scheme for enhanced relativistic spaceflight by means of compensating gravity generators with high-gravity settings may have been in vain.

a4android
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    That has such delightful potential to go horribly horribly wrong – Separatrix Jan 03 '18 at 11:42
  • @Separatrix Oh yes, there is absolutely no way that this will ever cause your crew to be turned into puddles of fleshy goo on the ceiling. Yep, no chance at all. – kingledion Jan 03 '18 at 12:48
  • @Separatrix I'm glad you noticed. But fortunately the infallible technology installed in the Exciting Undertaking has it under control. Lowest possible tender, you say. Where does that enter into the equation? No way! – a4android Jan 04 '18 at 00:53
  • Interesting. Your conjecture leads to some interesting physics. Time dilation is also mediated by gravity. Could these gravity plates be used to reverse the effects of time dilation due to speed? I am not about to do the math, but would accelerating to almost cee in four days cause the 'drive' portion of the ship to be at a much higher velocity than the far-away-from-drive section? The closer to the gravitational source, the slower time goes. But it has to be 'true' gravity. not apparent gravity due to acceleration. Make EVERY point in the ship a 'high gravity' source? – Justin Thyme Aug 28 '18 at 15:44
  • And does artificial gravity cancel artificial gravity? Would a 100g source at one end and a 99g source at the other end cancel to 1g? Or would they both 'pull' each other with a net 199g? Would the time dilation effects due to gravity be equivalent to 1g, 100g, or 199g? – Justin Thyme Aug 28 '18 at 15:53
  • @JustinThyme You raise interesting points. Taking a conservative approach, the weird mechanism generating the artificial gravity (AG) is the only departure from physics as we know it, then AG behaves like normal gravity. AG should also produce gravitational time dilation. The two sources of AG should behave like ordinary gravity sources & cancel accordingly leaving 1 g. Internal acceleration or 'gravity" will depend on the distribution of ceiling gravity plates & whether AG is directional (if AG is generated on only one side of a gravity plate). – a4android Aug 29 '18 at 02:25
  • @JustinThyme The increase in time dilation due to gravitational time dilation caused by a 100 g field will be relatively small. Like yourself, I am interested how relativistic and gravitational time dilation act together. – a4android Aug 29 '18 at 02:27
  • @ a4android With two very big planets, the gravitational attraction of each combiners to increase the attraction, does it not? Each on the other? That's why the query about two plates, 99g and 100g, at opposite ends. Wouldn't they attract each other with 199g force? It would take some structural integrity to keep them apart. So somehow accelerating at a rate that would produce 100g's, countered by a plate that produces 99g's, sounds a lot like bootstrapping. – Justin Thyme Aug 29 '18 at 17:00
  • Lifting yourself in the air by grabbing your feet and pulling up. – Justin Thyme Aug 29 '18 at 17:02
  • @JustinThyme The forces involved have directions & that determines how they combine and their strengths at any point. There aren't two sets of gravity plates. Imagine the ship as a single cabin. There is a rocket motor under the floor with a 100 g acceleration. In the ceiling are a set of 99 g gravity plates. One force acts down & the other forces acts upwards. Therefore, (100 - 99) g = 1 g. This is not bootstrapping, just the application of force laws & Newtonian mechanics. Structural integrity is needed with a 100 g propulsion system & 99 g gravity plates. – a4android Aug 30 '18 at 04:31
  • @a4android Happless Harry is out in space beside a ball. Neither are accelerating, both motionless wrt each other, The ball takes off at 100g acceleration. HH stays behind, still stationary, So now a rope goes between HH and the ball. He is pulled with 100g acceleration but motionless wrt the ball. The rope has 100g tension in it. Replace the rope with a gravity pull of 99g, HH falls behind at -1g acceleration. Now put the rope back in. There is now 1g of tension in the rope. HH and the ball are motionless wrt each other. But HH is still feeling 100g of pull from the ball., – Justin Thyme Aug 30 '18 at 13:08
  • @JustinThyme Yeah, but HH's net acceleration is 1 g, That how the acceleration & the gravity balance each other. The rope trick only confuses the matter. – a4android Sep 02 '18 at 07:41
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(The following assumes "proper" artificial gravity, i.e. that is, as long as you do not try to move the source, indistinguishable from real gravity. Not sth. which is directed, like the electric field in a capacitor.)

Basically, the graviational field of a point-like source decays with square of the distance, of an infinite rod linearly with distance, and of an infinite plane is constant. For a finite-size ship, that's still approximately true as long as you're significantly closer to the source than to the edge of the source.

You surely want the gravity gradient to be small on the length of a human body to avoid a lot of upturned stomachs. ;-) That rules out a point source, because you have to stay far away from it, and you have to make it dangerously strong. A rod-like source would still mean a huge inaccessible space in the center of your ship, and it's unclear to me how you would hold it, because it would still crumble any construction material in close distance.

So the most sensible, economic idea is probably a flat generator, with a pyramidal multi-story ship on one or both sides. Make the pyramid a bit higher to add rooms with lower gravity. The generator tiles in the outer area are turned up a bit, so you don't have to tilt the floor too much in that area.

That's also the big problem with adjustable gravity (unless you do it ship-wide): If your neighbour thinks he wants to sleep at $0.6g$ tonight instead of the regular $0.8g$, your glassware falls out of the cupboard, not to mention the danger of the same cupboard falling onto you.

As to the absolute $g$ value, that's totally in your hand. If the generator running costs are cheap, go with $9m/s^2$. Otherwise I'm sure humans would do fine with 5 or even 4. Maybe have a gym with higher gravity on the other side of the plane and lock your spacefarers in there for one hour on every weekday.

Karl
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    But doesn't gravity always pull towards the 'center of gravity', no matter what the surface configuration or shape? – Justin Thyme Jan 02 '18 at 16:00
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    @JustinThyme Not exactly. A planar generator looks to everyone on the surface like a (incredibly strong) point source located far away under the plane. The surface (outer, at the same radius) gravity on earth would be the same if all the mass was concentrated in a singularity at the center. – Karl Jan 02 '18 at 16:03
  • All this assumes of course "regular" gravity, only it's not generated by a huge amount of mass . On USS Enterprise, they obvously have things working quite differently. – Karl Jan 02 '18 at 16:09
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    Like, apparently, that single point source is somewhere out in the middle of space, 'below' the ship. – Justin Thyme Jan 02 '18 at 16:14
  • Indeed, only the films show other vessels fly underneath the Enterprise without any extra effort. ;-) – Karl Jan 02 '18 at 19:36
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    Obviously a different inertial fame of reference. – Justin Thyme Jan 02 '18 at 19:45