An often overlooked piece of tech in sci-fi

[Eternal_Freedom]

We all know that sci fi has some awesome technology in it. Rayguns hyperdrive, energy shields, teleporters and so on. But there is one piece of tech that (most) series have that is almost never elaborated on: artificial gravity

It gets taken for granted in every sci fi film I've seen

Now I know that various people on this board have come up with ideas and theories and so on about how turbolasers and phasers and hyperdrive might work, but does anyone hve the faintest clue how AG might work?

I ask because as I said, it's overlooked often

[GrandMasterTerwynn]

We all know that sci fi has some awesome technology in it. Rayguns hyperdrive, energy shields, teleporters and so on. But there is one piece of tech that (most) series have that is almost never elaborated on: artificial gravity

It gets taken for granted in every sci fi film I've seen

Now I know that various people on this board have come up with ideas and theories and so on about how turbolasers and phasers and hyperdrive might work, but does anyone hve the faintest clue how AG might work?

Disregarding simulated gravity through centripetal acceleration of rotating habitats, elf magic. The closest you could conceivably come is, if you had arbitrary control of the electromagnetic force, is the manipulation of the electromagnetic moment possessed by every molecule. How you will get it all to line up, while accounting for the fact that ferromagnetic metals will react far more strongly than, say, animated sacks of protein-water, is an exercise best left to the reader.

Otherwise, as any physicist will tell you, the only way to generate planetary scale gravity is by planetary-scale mass. Ergo, all artificial gravity is elf magic and any technobabble will do to explain it.

Examples of technobabble include "Future scientists prove that gravity doesn't really work that way, and through <magic> we can produce gravity without having to drag down an Earth-mass of matter with the intrepid hero's spaceship."

[Guardsman Bass]

Examples of technobabble include "Future scientists prove that gravity doesn't really work that way, and through <magic> we can produce gravity without having to drag down an Earth-mass of matter with the intrepid hero's spaceship."

I remember Arthur C. Clarke had a story that had something like that called The Trigger. The story was actually about them somehow figuring out how to use the technology to stop all gunpowder from working (it wasn't one of his better novels), but the basis of the technology was that they'd somehow figured out how to manipulate "gravitons" or something like that after figuring out a Grand Unified Theory of Physics.

Now I know that various people on this board have come up with ideas and theories and so on about how turbolasers and phasers and hyperdrive might work, but does anyone hve the faintest clue how AG might work?

Not really. It's pretty much just "black box" technology - you can see how it works in a fairly consistent science fiction setting, but you have no idea of how such a thing might even be possible.

[Marcus Aurelius]

Otherwise, as any physicist will tell you, the only way to generate planetary scale gravity is by planetary-scale mass. Ergo, all artificial gravity is elf magic and any technobabble will do to explain it.

Examples of technobabble include "Future scientists prove that gravity doesn't really work that way, and through <magic> we can produce gravity without having to drag down an Earth-mass of matter with the intrepid hero's spaceship."

In the Hyperion Cantos they don't actually have artificial gravity but energy fields that press things downwards towards the floor, which gives them a reasonable simulation of gravity. But of course that is just a technobabble explanation as well, just a slightly more creative one than the standard AG magic in scifi.

[Imperial528]

This is a bit of corner-cutting, but if the floor was essentially a large electromagnet, or a strong enough permanent magnet, then one could put magnetic metals inside of uniforms so that the clothes are pulled down at 1g, thus holding down the person wearing them.

Clearly, in any sci-fi I've seen, that isn't the case, since the uniforms aren't too shiny (which would indicate metal threads in the weave) and they are rather flexible all over (which rules out plates placed in certain areas). That and things like paper and food are still held down.

[Junghalli]

Disregarding simulated gravity through centripetal acceleration of rotating habitats, elf magic.

Don't forget acceleration gravity. Only works when the ship is accelerating though, obviously.

One neat possibility, if you have the technology for it, is to make your ship a utility fog environment and have the u-fog physically hold down objects to simulate gravity. It wouldn't be an exact simulation - the stuff inside your body wouldn't be effected by it for instance - but it would do for explaining why the characters in your TV show aren't floating around.

[Steel]

The potential energy thing really isn't an issue. What happens when you turn on a powerful electromagnet in a scrapyard? Suddenly theres a magnetic field powerful enough to lift a car and that didnt make the universe implode due to the fact that we forgot some bookkeeping on the potential energy on something a mile away.

Artificial gravity certainly requires magic, but not so much magic. Consider it is possible to set up a uniform electric field between two plates so just handwave in a gravitational dipole... Oh wait thats rather a lot of magic...

[Imperial528]

With an electromagnet, the potential energy exists at the switch between it and the power source. To elaborate, the charge in the wire has voltage, but the resistance is high enough that it can't flow. When the switch is triggered, the resistance drops to a level that the charge can easily overcome, at which point there is a current, so the potential energy has been converted to do work.

Now, I feel like I may not have been clear above (I don't know why, it just seems too simple to be clear...) So, here's a nearly identical situation:

You are trying to push a sliding door open, but a deadbolt is stopping you from moving the door. You are expending energy, so there is the potential to do work, however, you can't get the deadbolt to break. If someone were to remove the deadbolt, there would no longer be any significant resistance to you, so the potential energy you were putting into the door gets converted into kinetic energy, at which point you are doing work.

If you understood the first one, good, I just feel like I didn't explain it well enough. The second one will be good for those with no knowledge of electricity.

[Darth Yoshi]

As I understand it, the potential energy in such a system comes from whatever's powering the magnet. The magnet is the active force, aligning the individual magnetic fields of the atoms by virtue of being there, but it requires a current of some sort to generate a field.

[Tanasinn]

Seriously, what does happen there? (I dropped out of physics school before this point.) The potential energy surely can't be popped out of nowhere - does it already exist, locked up in the atoms, but randomly aligned do it doesn't actually do anything until turned on?

Fuckin' magnets, how do they work?

As to artificial gravity, I personally rather feel the standard answer of "ignore it" is best. Technobabble seems to create more problems than it solves a lot of the time. I suspend disbelief with the standard "we got something in physics wrong" line.

[Simon_Jester]

The potential energy thing really isn't an issue. What happens when you turn on a powerful electromagnet in a scrapyard? Suddenly theres a magnetic field powerful enough to lift a car and that didnt make the universe implode due to the fact that we forgot some bookkeeping on the potential energy on something a mile away.

Seriously, what does happen there? (I dropped out of physics school before this point.) The potential energy surely can't be popped out of nowhere - does it already exist, locked up in the atoms, but randomly aligned do it doesn't actually do anything until turned on?

Physics grad here.

With an electromagnet, potential energy is a non-issue; you don't have to supply it. When I switch an electromagnet on, the power plant does the work of moving the bits of metal around (it gets this energy by tapping the flow of a fluid through pipes using a turbine). The potential energy only exists from a bookkeeping standpoint; as long as nothing moves and no internal changes occur inside the materials the magnet pulls on, no work is done and no energy has to be supplied.

The same could go for artificial gravity, if it works like a magnet pulling you towards the floor. The work done is relatively minimal (as long as you don't fall very far). Power requirements might be fairly small relative to all the other power-hungry devices on the ship (like laser cannons).

Note that you do NOT have to worry about the "potential energy" of objects infinitely far from the ship, unless the AG field affects those objects. The potential energy of an object that feels zero force due to the AG field has nothing to do with whether the AG field is on or off, and therefore the AG generator need not supply energy to do anything to that object. After all, nothing happens to it; it's outside the hull and far away, and if you turn the generator on it doesn't move.

[Feil]

As long as you're working magic, you might as well have the artificial gravity be an approximate plane-wave source, thereby no decay with distance. At large distances from a finite source, all waves are sphere waves, so 1/r^2 falloff will begin. Any remotely realistic interaction with other objects will be over so fast, or at such a great distance, that the gravity effect wouldn't be noticeable; and coping with artificial gravity effects of other vessels would be easily within the realm of any of the super-high-tech space ships that use elf-magic gravity in the sci-fi I've encountered, just through reaction-based linear acceleration. As for people inside the other ships - again, as long as we're using elf magic, we might as well put them inside a gravity-equivalent of a Faraday Cage. Problem solved. A gravity Faraday Cage would also have the advantage of letting the magic gravity pass over the ship without affecting it at all.

[starslayer]

I mean, yeah, it's all elf magic, but you can be really cool with your elf magic by using what Steel described above. The dipole would then involve negative mass, which opens some really interesting cans of worms (for one, stable wormholes are now possible as a direct consequence, and Alcubierre like drives become possible). See? Artificial gravity, FTL, and time travel in one go, using just one physics breaking thing! Of course, it really, really, really breaks physics, but what the hell.

[Freefall]

Something I'm wondering about is why on shows like Star Trek and Star Gate, they can apparently "gravitize" the floors on the inside of the ships so easily, but can't do it to the outside of the ship at all. Anytime they have to go for a surface walk, they break out the magnetic boots.

My guess is something along the lines of, "that would look silly."

To be more fair, I guess it is an assumption on my part that the artificial gravity is actually an attractive force being generated by the floor, as opposed to a repulsive force generated by the ceiling, but that's how it always seems to be presented to me.

[Lord of the Abyss]

This is a bit of corner-cutting, but if the floor was essentially a large electromagnet, or a strong enough permanent magnet, then one could put magnetic metals inside of uniforms so that the clothes are pulled down at 1g, thus holding down the person wearing them.

Clearly, in any sci-fi I've seen, that isn't the case, since the uniforms aren't too shiny (which would indicate metal threads in the weave) and they are rather flexible all over (which rules out plates placed in certain areas). That and things like paper and food are still held down.

I've never seen this route taken, but it occurs to me that one possibility would be bioengineering; alter people so their tissues are more responsive to magnetism. That would still leave you with floating foods and liquids though.

Disregarding simulated gravity through centripetal acceleration of rotating habitats, elf magic.

Don't forget acceleration gravity. Only works when the ship is accelerating though, obviously.

One neat possibility, if you have the technology for it, is to make your ship a utility fog environment and have the u-fog physically hold down objects to simulate gravity. It wouldn't be an exact simulation - the stuff inside your body wouldn't be effected by it for instance - but it would do for explaining why the characters in your TV show aren't floating around.

Another idea is the one that Charles Sheffield was fond of; generate gravity by just concentrating a huge amount of mass under you (or over you, for levitation) in the form of condensed matter.

[AMT]

There was a Star Trek novel called Best Destiny a few years back that had a nice type of artificial gravity I thought, though not sure how probable it'd be.

It basically had a super concentrated gas spinning extremely quickly within a housing, generating a gravity field. It apparently also worked for inertial dampening, since when Kirk broke it, it caused people to go flying into walls and whatnot due to the acceleration of the ship, which they had to stop and then use minimal thrust until it was fixed.

[Zaune]

The work of Eugene Podkletnov makes a perfect candidate. His theories are sufficiently plausible-sounding to pass muster for anyone not intimately acquainted with high-energy physics, and he's cool-sounding name for Fields or Effects or whatever you want your anti-gravity magitech to run on.

There's even an outside chance that he's not a complete crackpot.

[General Zod]

Something I'm wondering about is why on shows like Star Trek and Star Gate, they can apparently "gravitize" the floors on the inside of the ships so easily, but can't do it to the outside of the ship at all. Anytime they have to go for a surface walk, they break out the magnetic boots.

My guess is something along the lines of, "that would look silly."

To be more fair, I guess it is an assumption on my part that the artificial gravity is actually an attractive force being generated by the floor, as opposed to a repulsive force generated by the ceiling, but that's how it always seems to be presented to me.

From a design standpoint it would be a waste of energy and resources to gravitize the outside of the ship. How often do you need to go out there anyway?

[Captain Kruger]

If you're talking AG there's another can of worms in the form of inertial dampeners. Creating 1G is one thing; nullifying hundreds or thousands of G-forces is something else entirely.

[Simon_Jester]

If you're talking AG there's another can of worms in the form of inertial dampeners. Creating 1G is one thing; nullifying hundreds or thousands of G-forces is something else entirely.

Arguably they're very similar problems; it's "just" a question of cranking the power up by a few orders of magnitude.

An extremely powerful AG field pulling everything on the ship 'up' towards the nose, synchronized with a drive pushing it from 'below' at the tail, would be a relatively elegant way to avoid inertia from high-acceleration thrust.

From a design standpoint it would be a waste of energy and resources to gravitize the outside of the ship. How often do you need to go out there anyway?

...Very frequently? There's a lot of stuff out there that needs to be maintained and monitored. It's like asking "how often would the crew of an oceangoing ship need to go on deck anyway?"

The outside of the hull is the 'operational surface' of the ship. It's going to be packed with useful devices, and having them go wrong will compromise the ship's usefulness.

[General Zod]

...Very frequently? There's a lot of stuff out there that needs to be maintained and monitored. It's like asking "how often would the crew of an oceangoing ship need to go on deck anyway?"

The outside of the hull is the 'operational surface' of the ship. It's going to be packed with useful devices, and having them go wrong will compromise the ship's usefulness.

It just seems like maintenance is less of a concern when you're talking about ships that can go FTL. But they have to go out there in space suits anyway thanks to the whole no atmosphere thing, so it seems kind of a waste to just give them gravity but no ability to breathe. So why use up so all that energy?

[keen320]

One neat possibility, if you have the technology for it, is to make your ship a utility fog environment and have the u-fog physically hold down objects to simulate gravity. It wouldn't be an exact simulation - the stuff inside your body wouldn't be effected by it for instance - but it would do for explaining why the characters in your TV show aren't floating around.

What is u-fog?

Anyway, I suppose maybe we could figure out artificial gravity if we knew why gravity does what it does. I mean, all we really know is that there is an attractive force between matter and that it increases with mass. From what I know, we don't really know why it does that.

Oh yeah, forgot about relativity. So, what, we'd need to find out how to artificially curve space-time? Okay, similar idea, maybe if we magically found out how mass does that? No bigge

[Junghalli]

What is u-fog?

This.

[Nyrath]

Dr. Robert Forward said that our current technology allows us to easily manipulate electromagnetism because we can take electromagnetic charges (in the form of electrons) and accelerate them to near the speed of light (say with a copper wire and a battery).
By the same token, he said that the only way we will easily manipulate gravity is when we gain the ability to take gravidic charges (in the form of neutronium or quantum black holes stabilized in some unknown manner) and accelerate them near the speed of light (using some as yet unknown technology)

[Freefall]

From a design standpoint it would be a waste of energy and resources to gravitize the outside of the ship. How often do you need to go out there anyway?

The thing is though, how much energy and resources does it take? In Star Trek at least, the AG system is by far the most stable system they have. Even life support can fail without any apparent failure in the AG. It exists perfectly uniform on every level of the entire ship. They never have to reroute power from auxiliary or other systems to maintain it, nor do they ever attempt to reroute power from whatever the AG system is. Even their Shuttlecrafts have perfectly functioning AG, and they've had it going back at least as far as the NX-01 under Archer.

Seriously, there must have been an absolutely astounding breakthrough in their theories of gravity at some point. They can't even make their doors work right 100% of the time.

Now, to the question, why bother, what's the point? Well, as mentioned, it would be great for maintenance crews. Even if they still need suits, being in an AR environment means that they don't have to worry about tools and such floating away, and they don't have to worry about themselves floating off if they manage to separate their boots from the hull by more than 2 or 3 inches.

They don't have to keep it on all the time, of course, but it just seems like if it's so easy to install in the floors of even a shuttlecraft, it could definitely come in handy.

Like I said though, this is all predicated on the idea that they are generating an attractive force in the floor. The more I think about it, a repulsive force from the ceiling might be more reasonable. Maybe some sort of exotic particle that can transfer momentum fairly well to solid objects (put apparently passes through air without hitting anything). Or I guess they could have figured out the magic of how to easily produce gravitons.