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2019-07-19, 04:12 PM (ISO 8601)
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Cool things to do with Gravity Plating
Pretty much what it says n the tin here. I'm thinking of a sci-fi universe that is fairly hard on the starship front. Lots of various thrusters, FTL is only available through gates, etc. However, I don't want to deal with the various forms of gravity, so I came up with an element that, when properly refined and has a current ran through it produces gravity.
Now, obviously, this would cause massive tech issues. Why don't they use Gravitic Rail guns? Why don't they have Gravity Distortion Drives? And on and on. So my solution was to make it relatively simple to get it to 1 G, but it takes about 15 minutes of "warming up the plate" before it gets there and going much higher than, say 3 or 4 g gets prohibitively power intensive.
So, please try and break this so I can find the holes in it.
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2019-07-19, 04:43 PM (ISO 8601)
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Re: Cool things to do with Gravity Plating
First thing that comes to mind to me is having 0G rooms planetside by having a plate cancel out planetary gravity. Which would probably enable all kinds of shenanigans. Also, space elevators, with 0G vacuum tubes reaching from ground to space?
Resident Vancian Apologist
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2019-07-19, 05:02 PM (ISO 8601)
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- Tharggy, on Tellene
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Re: Cool things to do with Gravity Plating
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2019-07-19, 05:28 PM (ISO 8601)
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- Jan 2007
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- Switzerland
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Re: Cool things to do with Gravity Plating
Well, 0G would still mean that you could build with materials that are ten times heavier and accelerate faster, so that would still help a lot with building space elevators.
Of course, you can also build a perpetuum mobile if you have differential gravity like that, I'd think. A wheel with weights on it, so that the weights fall in 1G and go up in 0.1G should produce a lot of energy very simply.Last edited by Eldan; 2019-07-19 at 05:28 PM.
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2019-07-19, 05:39 PM (ISO 8601)
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- Oct 2012
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Re: Cool things to do with Gravity Plating
Huh, so a revolution in energy production then? Makes sense actually. Get a bit of electricity going until the thing can spin itself and then just let it power itself while you use the surplus. I guess I could see this getting used in places where a Fusion Generator isn't feasible or for the more homesteader types
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2019-07-19, 06:42 PM (ISO 8601)
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- Jan 2007
Re: Cool things to do with Gravity Plating
Limitless power generation is the key thing and the other big revolution comes from this material becoming a reactionless propulsion drive. You ask why it is a big thing? Well, a typical rocket needs to haul both fuel and reaction mass for the thrusters. The more fuel and mass you have gathered, the more of it you need to achieve the same speed and so on. If you will not need any fuel or reaction mass, spaceships suddenly become lightweight, efficient and do not have to wait for specific planet positions to reach their destination. It does not have to have high thrust to be extremely useful.
It also causes serious problems (if you do not know this site, it is an amazing source on hard science and SF on spacecrafts).
Even if those gravitic plates did obey the third Newton's law somehow, the free energy would cause the same issue of limitless propulsion, since you can just have a photon drive.
An inevitable mention: Cavorite.In a war it doesn't matter who's right, only who's left.
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2019-07-19, 06:49 PM (ISO 8601)
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- Oct 2012
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Re: Cool things to do with Gravity Plating
Would some of these issues be dealt with if it required more and more energy to effect larger things? So you couldn't just loop a field around a ship and make it weigh nothing without taking a frankly moronic amount of energy, but keeping people standing in a hallway relatively simple.
This would also prevent unlimited energy on a large scale as the massive turbines required would be too heavy to have a reasonable energy cost compared to Fusion
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2019-07-19, 07:08 PM (ISO 8601)
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- Jan 2019
Re: Cool things to do with Gravity Plating
Don't know why you immediately assume conservation of energy is thrown out. You even already have a current going through it, so all you need is the voltage to vary depending on how things are moving and all conservation laws can hold. It would work similarly to an electromagnet, only it affects everything.
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2019-07-19, 07:34 PM (ISO 8601)
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- Tharggy, on Tellene
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Re: Cool things to do with Gravity Plating
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2019-07-19, 08:41 PM (ISO 8601)
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- May 2007
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- Tail of the Bellcurve
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Re: Cool things to do with Gravity Plating
I mean running electricity through something already turns it into a gravitational magnet, so to speak. Electricity being energy bends space just like mass, although since m = e/c^2, it takes a lot of energy to bend space the same amount as a little bit of mass. From a moving things perspective the electric charge is vastly more interesting than the extra gravity.
What you really need is either for this mystery substance to bend space a lot more than it should, given the charge you put into it, or else bend it the other way - it's an anti-gravity magnet. And even then, you'd probably want it to unbend space hyper-efficiently.
As to why you don't build gravitational railguns, it's because the gravitational constant is way smaller than the electromagnetic/fine structure constant.Blood-red were his spurs i' the golden noon; wine-red was his velvet coat,
When they shot him down on the highway,
Down like a dog on the highway,And he lay in his blood on the highway, with the bunch of lace at his throat.
Alfred Noyes, The Highwayman, 1906.
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2019-07-19, 09:19 PM (ISO 8601)
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- Oct 2012
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- Tharggy, on Tellene
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Re: Cool things to do with Gravity Plating
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2019-07-19, 11:46 PM (ISO 8601)
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- Aug 2011
Re: Cool things to do with Gravity Plating
So is this tech producing actual gravity, or just something like gravity? Gravity follows the inverse square law, so halving your distance from the source quadruples the gs experienced. As described, it sounds like if you have a plate that pulls at 0.5g from the other end of the room, it's going to be pulling at hundreds of gs right next to it. I'm not sure how a gravity plate would even stay intact. Maybe I'm misunderstanding something, but my intuition is that the pressure across the plate would crush it like a pop can.
And then there's the fact that gravity is incredibly long reaching. If you're creating earth-like gravity on the surface of a planet, the moons of that planet suddenly experience that on top of the planetary gravity (both come from basically the same point at that distance). That's going to cause a huge change in their orbits.Originally Posted by crayzzOriginally Posted by jere7my
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2019-07-20, 02:44 AM (ISO 8601)
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- Jul 2017
Re: Cool things to do with Gravity Plating
Any reason you don't just have your spacecraft set up so that they can spin for artifical gravity? Spin = centrifugal force = people standing instead of floating around is a sci-fi trope for a reason, and it hits the sweet spot between hardness and simplicity that few people will run the numbers on you.
If you want to be hard-ish and are absolutely insistent on artificial gravity, we've found ways to (technobabble mumbo-jumbo) and that allows certain perturbations in the electromagnetic field to create noticeable warpings of the local gravitational field. You have circuitry patterns and graviton emitters as opposed to having everything rest on the fantasy material, but again this gives you the result of people standing on solid ground with minimal added complications.
As a bonus, have someone mention that energy conservation still holds. Lifting an object in an antigrav room on earth will take roughly the same amount of energy that having a machine lift the object would take. There might be a few cases where making something feel heavier or lighter can be the best way to go about a problem, but you manage to avoid issues with perpetual motion machines and other oddities that shake out of antigrav physics.
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2019-07-20, 03:59 AM (ISO 8601)
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- Feb 2007
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Re: Cool things to do with Gravity Plating
If you can actually generate gravity like this, is there any reason why you couldn't use it for thrust as well? None of those messy reaction drives.
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2019-07-20, 08:17 AM (ISO 8601)
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- May 2007
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- The Land of Cleves
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Re: Cool things to do with Gravity Plating
Don't make it a gravity magnet. Make it, literally, a magnet. All substances are magnetic; some are just more magnetic than others. You can get water (e.g., a human body) to react to a magnetic field, if it's strong enough. Just put some magnets in the ceiling to diamagnetically push water downwards, and you can have people walking around on the floor.
Once you have such a system, you can also us it to cancel out the effects of high acceleration... to a degree. The limiting factor is going to be that bones have a different diamagnetic susceptibility than more watery parts, but they all react the same way to gravity/acceleration. So if you try to cancel out too much acceleration, you end up with your bones pulled one way and your flesh pulled the other.
This effect would also be present, though to a less dramatic degree, even at a normal 1 g. It wouldn't be dangerous, but it probably would be a bit uncomfortable to those who weren't used to it. Which provides you with a plot justification for flatlanders getting "spacesick" and having to "find their space legs", which might be useful for your story.Time travels in divers paces with divers persons.
—As You Like It, III:ii:328
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Current Homebrew: 5th edition psionics
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2019-07-20, 08:23 AM (ISO 8601)
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Re: Cool things to do with Gravity Plating
Wouldn't a magnet strong enough to produce an appreciable effect on a human be strong enough to rip a metal ship apart?
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2019-07-20, 08:42 AM (ISO 8601)
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Re: Cool things to do with Gravity Plating
Because I don't want to have to design the ships around spin gravity. Thats really my only reason.
Well that simplifies thngs greatly. I may just go with that.
Well, not if its space material making up the magnet so it doesn't react to ferrous metals.Last edited by Blackhawk748; 2019-07-20 at 08:44 AM.
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2019-07-20, 08:50 AM (ISO 8601)
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- Jan 2007
Re: Cool things to do with Gravity Plating
Yes, very much so. A standard MRI scan uses fields strong enough (around 1.5 T magnetic field) to be dangerous in a presence of any metallic object. The policy is no piercings, amalgam tooth fillings, no nothing - prepare like for a meeting with Magneto. Magnetic fields needed to exert 1 G on a living being is about 16 T.
For reference, a typical junkyard electromagnet generates a field of 1 T at the surface.In a war it doesn't matter who's right, only who's left.
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2019-07-20, 09:18 AM (ISO 8601)
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Re: Cool things to do with Gravity Plating
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2019-07-20, 11:02 AM (ISO 8601)
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- Oct 2012
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Re: Cool things to do with Gravity Plating
I do, but I'm ok with making up new materials to work with inside this universe as I'm sure that there are very strange minerals and elements out there that would seem pretty fanciful to the rest of us. Clearly a "water magnet" wouldn't be a proper magnet as we know it, it'd probably even have a different name scientifically speaking.
What I want is for this all to make sense inside of itself. Thus why I asked about Gravity Plating. I want to know what the repercussions of something like that in a world that works off of our basic understandings of physics would be. I'm ok with adding weird almost "magicky" stuff to the setting, I just want it to be incorporated properly into the rest of the setting in a way that makes it all seem plausible.Last edited by Blackhawk748; 2019-07-20 at 11:04 AM.
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2019-07-20, 11:26 AM (ISO 8601)
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- May 2007
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- Tail of the Bellcurve
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Re: Cool things to do with Gravity Plating
I always find it useful to keep in mind that it's not an asspull if it's explained in the first fifty pages or so of a book, it's the buy-in for the setting. It's an asspull if it's in the climax of the story and none of it has been explained yet.
Blood-red were his spurs i' the golden noon; wine-red was his velvet coat,
When they shot him down on the highway,
Down like a dog on the highway,And he lay in his blood on the highway, with the bunch of lace at his throat.
Alfred Noyes, The Highwayman, 1906.
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2019-07-20, 06:14 PM (ISO 8601)
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- Sep 2008
Re: Cool things to do with Gravity Plating
It's also not an asspull if its implications are explored, like we are doing rather than as simply a way of 'explaining' why their feet are touching the floor when they should be in freefall, unless you are explicitly making the kind of setting (Star Wars comes to mind) where the whys and wherefores don't matter in the first place, in which case you probably don't need to bring up gravity plating in the first place.
Technology like this, the ability to turn gravity on and off in a localized fashion, would change, well, everything. You don't need to explain 'how' it works, frankly, this is just magic, but it is good to show that the engineers in your 'verse have the creativity of your average reader in coming up with applications for something like this.
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2019-07-20, 11:24 PM (ISO 8601)
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- May 2007
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Re: Cool things to do with Gravity Plating
Frankly I don't even really care about that all that much anymore, at least beyond a very basic sort of first level consistency check. Or at least I'd say it's very low on the list of things to worry about.
I feel like the existence of the internet has inflicted upon people the false impression that they need to cater to the whims of an endless sea of deeply pedantic, often bad faith, nitpickers, or they've failed. Like on these boards, you see questions all the time about 'is technical thing X consistent or realistic.' And usually it isn't and it gets ripped to shreds, and everybody pats themselves on the back and feels smart, and the story goes unwritten because now the questioner feels stupid.
This does not seem like any sort of win to me.
Like sure, yes, if you have reactionless drives you also would logically have planet-killing missiles. Unless your story is going to fundamentally be about planet-killing missiles or is otherwise hard sci-fi (in which case there aren't any reactionless drives anyway), this is almost completely irrelevant. I've put a lot of books down because I found the characters tedious; I don't think I've ever given up on a story because goddamn it, this space opera heist story didn't consider that Space Count Villeous didn't need the ancient bioweapon, he could have just ramped his space yacht up to .95c and crashed it into the Planet of Helpless Utopian Hippies.Blood-red were his spurs i' the golden noon; wine-red was his velvet coat,
When they shot him down on the highway,
Down like a dog on the highway,And he lay in his blood on the highway, with the bunch of lace at his throat.
Alfred Noyes, The Highwayman, 1906.
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2019-07-21, 02:26 PM (ISO 8601)
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- Feb 2007
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- Manchester, UK
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Re: Cool things to do with Gravity Plating
I don't think a reactionless drive implies you can easily get a ship up to near lightspeed, does it? The energy requirements to get to such a speed are still so colossal that I don't think you can just handwave them away, plus you'd also need pretty darned dope radiation shielding on the front of your ship when every stray electron you bump into suddenly has enough energy to kill you because of your speed. Or, to put it another way, it doesn't take a lot of thought to realise that turning a ship into a near-C impactor is really not a trivial process no matter what tech level you have.
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2019-07-21, 02:57 PM (ISO 8601)
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- Jul 2017
Re: Cool things to do with Gravity Plating
Not having to worry about fuel does mean that your ship can consistently accelerate, and consistent acceleration can get you very speedy remarkably quick. It doesn't solve the radiation problem and it certainly doesn't change the fact that space is big enough that it takes you ages to get anywhere even at lightspeed, nor does it solve the relativistic wackiness that stories often handwave. But if you can put something on a ship, you can also put it on a guided missile and turn that into a nasty weapon. The most extreme example of this being using a ship's warp drive to turn it into a kamikaze fighter, which asks the question of why unmanned warp missiles aren't a thing.
Getting out of the specifics of physics, though, I'm okay with the occasional handwave. If WALL-E were a little harder on the sci-fi and a little less Disney, it would still be a story about the effects of rampant consumerism. Having to fuss over the gravity on the spaceship would either turn the whole thing into an exploration on the physics of artificial gravity (completely missing the original point), or on the cultural and physical evolution aboard a generation ship without gravity (light years away from the original point). Sometimes it helps to at least sketch out the rules to explain why something can't be used far outside of what it's being used for, but that's a paragraph of technobabble at most. More than that, and you lose focus.
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2019-07-22, 03:07 AM (ISO 8601)
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Re: Cool things to do with Gravity Plating
You still need fuel to generate energy for your magic drive, though.
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2019-07-23, 06:24 AM (ISO 8601)
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Re: Cool things to do with Gravity Plating
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2019-07-23, 02:25 PM (ISO 8601)
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- Sep 2016
Re: Cool things to do with Gravity Plating
I don't think we'll escape some perpetual motion.
Although if the artificial gravity doesn't have 'magic' cutoffs (e.g. if it just behaves like a different mass source). Then the local differential will be smaller (of course that creates issues of it's own). At that point the weights fall in 0.3G and go up in 0.1G , with horizontal movement in 1G and 0G. Which if you have the rhetorical initiative might be clearly less than the cost of maintaining it in any practical sense.
Also grav is a weak force, if the cost of maintaining it is greater than an equivalent electromagnet, then you gain a bit more flexibility in your ammo over an E-M railgun but it isn't going to be magic (you'd need to find a second level of abuse).
Going back to the perfect Gravity-wheel, if we make it so the average fall is 1m and weighing about a ton revolving at 1Hz, then the power output is about 10,000Nm or 10kW which is a bit higher than an equivalent sized ideal solar panel but not vastly so. It might be truly free energy but not vast amounts (it is after all just a magic water wheel*). A philosophical game-changer rather than an economic one.
*one big difference is of course is that as it gets faster it emits more power etc... rather than having a maximum flow rate (this is why you need to be the one in command of the conversation).
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2019-07-27, 01:50 PM (ISO 8601)
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Re: Cool things to do with Gravity Plating
I'm trying to recall how I solved this for a Traveller game. I think it was that gravity generation devices used paired plates that produced a field between them that accelerated mass towards one of them at a constant rate. I think they had a required energy use slightly greater (90ish % efficency) than the total kinetic energy that they imparted to the mass, with a slight exponential energy consumption increase beyond 9 meters per second squared.
That was pretty much it. Restrict the area/volume of the effect and make sure it requires more energy input than you can get out of it.
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2019-07-29, 08:56 PM (ISO 8601)
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- Oct 2012
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Re: Cool things to do with Gravity Plating