# Fire is gravity for fire Elemental

What would it look like for elementals (type of creature based on its base element) if the base element acted as its gravity? How would they move about? How would their basic actions look compared to humans?

So a fire elemental might be pulled from its feet by a large explosion (explosion might not do damage to it), and the base gravity pull making it seemingly standing on the surface like humans would be the soft pull from the earth's fiery core.

I'm interested in a water elemental too. During intense rain storms they are able to leave bodies of water because of the amount of water in the air (albeit with some effort).

in terms of rules:

• momentum and centrifugal forces still apply to these creatures.

• these elementals are able to produce their element by magic and it should have the same effect. So, if a fire elemental throws a fireball large enough into the air it could jump higher, (edit based on @Cyrus's comment) but elementals of a type are not affected by each other's "bodies" in terms of pull (except maybe romantically if that happens)

• these creature are able to retain their form except under extreme conditions. So a water elemental in the ocean can move through the water (easier through currents) but escaping the ocean would be a heavy burden. It would need to wait for a storm and gather momentum

• The mass of the elementals was brought up by @Mithrandir24601. Their size would be about that of a human (can vary just like humans) but their weight would vary based on their element.

• Fire elementals weigh about a third of the weight a human of the same size would weigh. I would say they are a little lighter in the day due to the sun being above
• Water elementals are as heavy as water
• Earth elementals are the same weight of a human their size even though they may look heavier (rocky appearance sometimes with bits of metal)
• Wind is the same as fire in terms of natural weight

I'm thinking similar rules of gravity, like the larger the amount of it the harder the pull on what it affects, but alternatives are welcome.

• Does the elemental also attract the element, or is it only that the magic essence of the elemental is attracted by the fire/water/earth/air? Aug 5, 2016 at 8:32
• Can we also assume that when you say 'the base element act[s] as it's gravity' that we can ignore the 'regular' gravity that arises from mass/spacetime curvature? Also, what are the (real) masses of these elementals (even in comparison to something) and how is this different to the 'mass' that they interact with the base element in. Are there any repulsive possibilities? (i.e. is the fire elemental repelled by water?) Aug 5, 2016 at 8:35
• @Cyrus no the elementals of the same type don't attract each other, only the magic of the element they produce Aug 5, 2016 at 9:07
• @JDługosz thanks for the edit and thanks for the reminder Aug 5, 2016 at 13:12
• You may be interested in Brandon Sanderson's Stormlight Archive series. It is heavy reading, but it includes some characters who are able to change which direction is "down" in a local area around themselves. Aug 5, 2016 at 15:23

If you want more of a "break free" effect, maybe have the force proportional to $1/r^3$ (inverse cube, like the force between two magnets) instead of the usual inverse square (gravity, electrostatic force). Or even $1/r^4$ or whatever you want. It can still scale linearly with mass the way gravity (${G M m}/{r^2}$) does, you just vary the scaling with distance.

That would also make it plausible for small nearby things (like fireballs) to have more of an effect than the Sun's pull. (Which only affects fire Elementals, not the Earth's orbit around the Sun, so would tend to pull fire Elementals off the surface during the day, counterbalanced by the pull of magma and stuff underground).

It's completely plausible for a force to have very different scaling with distance than gravity. Just don't call it gravity! For example, the Weak nuclear force is very short-range because the force-carrying particles have non-zero rest mass (unlike the photons that carry the electromagnetic force. This is why the electroweak force is unified at high energies: there is enough free energy for pair-production of the force carriers, so they can pop up like photons). I'm not saying you should go into that much detail (better to be vague than obviously wrong to people that know the subject), just that non-gravity-like forces happen without magic.

So you could even have a force that's more or less inverse-square over short ranges, but falls off dramatically at a certain distance.

There have also been proposed theories of gravity that modify it slightly over astronomical distances to explain things like the Pioneer (space probe) anomaly. (That's now pretty conclusively explained by thermal radiation pressure, ruling out some of the gravitational theories.)

Another plausible explanation for scaling different than inverse-square: extra spatial dimensions. i.e. direction(s) that Elemental stuff can move in that's perpendicular to x, y, and z. Inverse-square scaling happens because the area of a sphere scales with the square of radius. In 4-dimensional space, the analog of a sphere has a 3-D analog of area (actually a volume) that scales with the cube of radius.

So if the force (and force-carrying virtual particles) spread out in a 4th spatial dimension, it would scale as $1/r^3$. And you can still use the word "gravity" if you like.

Real theories have been proposed with properties like this, especially String Theory's extra dimensions which are "rolled up" / curved back on themselves, which limits the strength of the effect. One proposed effect is/was gravity being slightly weaker than $1/r^2$ over astronomical scales.

For this case, presumably it's a dimension that only Elementals can move in, not ordinary matter. So it can have a strong effect on Elementals without affecting normal physics. Perhaps moving in this dimension takes you between worlds, or between elemental planes and Earth.

Of course, it's easy to introduce inconsistencies if you aren't careful. (e.g. if there are lots of Elementals only a couple km away, they would exert some pull on Earth's air / water / fire / earth. (Assuming this force affects the inert element with an equal and opposite force to what the Elemental feels, otherwise you're violating conservation of momentum and conservation of energy.) Anyway, safer to just have the force carrying particles / fields spread out into the extra dimension(s), and not have the Elementals able to move along it. Otherwise they could bypass walls by going around them using this extra dimension, and stuff like that.

Remember that the shell theorem only holds with $1/r^2$ forces, so a short-range force will tend to pull Air elementals into the sky when they're on the ground. If it's stronger than gravity, they'd have to actively fly downwards or hold onto things to stay at surface level.

This Elemental force (E-gravity? gravitee? Etraction?) doesn't attract plain water to other plain water, for example. This means that buoyancy doesn't happen with respect to this force, because the displaced plain water wasn't affected by that force. (i.e. there's no extra pressure created by it).

We know this because Newtonian mechanics + fluid dynamics can accurately model the Earth's oceans (e.g. sea level heights around the world, and the deformation of the oceans due to Earth's spin rate). I think our models are detailed enough that we would have noticed if water attracted other water more than gravitationally, rather than just got the wrong value for some other free parameter.

Buoyancy due to gravity can overcome gravity + the extra force, if they're in the same direction, otherwise not.

Water density in the air is peanuts compared to a nearby ocean, even during a heavy rainstorm. A $1/r^3$ or $1/r^4$ force would make the effect of a storm more significant.

A water elemental leaving the ocean is like a human climbing a mountain. It's "uphill" all the way from the centre of mass of the ocean. Being at the edge of the ocean is like a human having climbed up a vertical shaft from the centre of the Earth.

However, the ocean is more like a thin disc than a sphere of water, so getting to the edge takes you farther from more of it. Unlike climbing outward from a sphere (where your weight will peak at the surface), your weight will probably drop off some as you approach the shore (especially since coastal water is shallower). However, with a $1/r^2$ force, the difference between getting to the edge and going another kilometre beyond is less significant than with a sphere. You're already pretty far from most of the water, so the total pull you feel doesn't drop off as much with distance from the shore. (So again, a $1/r^2$ force isn't going to give you much of a "break free of the ocean" effect).

If a Water elemental can "climb" more easily through water than by walking on land, it's going to be much easier to leave the ocean by going up-river until they're near an equilibrium between a large lake and the ocean.

• Nice answer, your explanations are much more in-depth than my own. Aug 5, 2016 at 20:09

I really like this idea, because it encourages creativity with what makes another world habitable for different types of elemental. For example, 'warm' ice planets with underground reservoirs would be good worlds for water elementals to live if we include the mechanic that, say, ice has less of an attraction that liquid water...

One of the important things to consider here is that gravity obeys an inverse square law. That is, moving twice as far away from a source of gravity reduces the pull by a factor of 4. There is also an interaction coefficient ($G$ in the case of gravity) which determines how strong the attraction is per base amount of the source material. This is very weak.

Let us assume that for fire elementals on earth, the solid parts of the core have a negligible effect, so that only liquid magma has concentrated enough fire magic to determine the attraction. Estimating this to be 5/6 by volume, we also have a distribution of fire magic concentrated much closer to the surface than the concentration of mass in the earth.

Consequently, we have two options, depending on preference: 1. Fire elementals are very agile, able to easily leave the surface of the earth if they burn hot enough (eg Fantastic 4 style). 2. Fire elementals are equally constrained by the Earth's pull as humans.

For fun character design, I would opt for the former. Unfortunately, with the assumptions made so far, the equivalent of the $G$ coefficient would have to be even smaller than for gravity, and consequently the effect of explosions and large fire-balls would be invisible. The inertial mass options you mention would determine the distinction between 1 and 2; smaller inertial mass makes flying feasible.

There is a solution to this: we assume that magma is actually also quite low in fire magic concentration. This could be justified by a 'magma is mostly rock, part fire' justification, and it could largely compensate for the $G$ value. If a fire ball is pure fire magic, be could say that magma is just 5 percent fire magic by volume. I think this ratio (1:20) would be about right for the `fire ball jumping' idea, but this avoids more complex mechanics of fire-magic concentration. Again, the 'attraction to explosions' idea still requires very close proximity, but in a context involving eg both a fire and an air elemental in a large explosion, they would be pulled in opposite directions by the event, which is fun. Then inverse square law means that the Sun would still not contribute noticeably to effects, just as its effects on the tide are not noticeable compared to the moon.

Finally, for your water elemental we again have a problem with the inverse square law. In order for the Earth to be sufficiently attractive to keep them here, the coefficient of $G$ would have to be much bigger, since all liquid water is found on the earth's surface and makes up only a tiny proportion of the Earth by volume! On the flip side, underground streams would generally be too far away and small to have much impact and allow them to escape. Water elementals in this model, assuming that we can ignore hydraulic pressure far underwater which is caused by conventional gravity, would be most comfortable around mid-depth in oceans with attractive material symmetrically distributed around them, as they would struggle to maintain the velocity to move far up or down. As I mentioned above, a different structure of world would make things much more feasible and make a planet much more hospitable!

I love the idea of a half human, half water elemental living on land, constantly feeling the pull of the ocean...

• Note that I have assumed that you wanted consideration of whether current Earth would be potentially hospitable with this mechanic, but I hope my answer will help you work out how to make your ideas feasible in a reasonably consistent way :) Aug 5, 2016 at 10:14
• Does this mean that earth source of gravity is where the air starts? way above sea level? would expect people would feel the same weight in a plane but i haven't looked if anyone weighed things far up there. would the natural water content in the air help water elementals? Aug 5, 2016 at 13:21
• The height that a plane flies above the ground is tiny compared to the radius of the earth; this diagram is reasonably to scale to give you an impression. Hence you're right, the weight difference is tiny. The Shell Theorem that @Azuaron mentions is worth a look. Aug 5, 2016 at 13:32
• "huge uncomfortable pressures they would be submitted to underwater": Extra pressure only happens if this Elemental Gravity force (e-gravity? gravitee?) attracts plain water to other plain water. We know this doesn't happen because Newtonian mechanics + fluid dynamics can accurately model the Earth's oceans (e.g. the high tides in the bay of Fundy, and sea level heights around the world.) If water attracted other water, I think our models are detailed enough that we would have noticed, rather than just got the wrong value for some other free parameter. Aug 5, 2016 at 15:05
• @PeterCordes Interesting point. Will edit. Aug 5, 2016 at 15:16

Some interesting anomalies would arise out of this:

• Except for earth elementals, who would function just like everything else.
• As shown by the Shell Theorem, wind elementals would have a natural resting position on the surface of the planet just like everything else. Except, they will (presumably) have a density similar to air, so will float/sink in the air as determined by that density/buoyancy. If they can change their density at will (by expanding/contracting their bodies), they will be able to change their buoyancy and, therefore, their height above the ground just as if they had a swim bladder.
• Water elementals may not have that much difficulty getting onto shore. While the ocean is certainly massive, by the time they get to shore they're actually not that close to most of it. Basically, they would "weigh" quite a lot on the open sea, but as they get closer to shore they'd get lighter and lighter. By the time they got to shore, depending on the "gravitational pull", it might even be like walking on the Moon is for us. Seems like teenage water elementals would probably run inland up major waterways for the freedom and fun it offers them. During storms, a sea-bound elemental would get lighter from all the rain in the air but probably not enough to float. A ground-bound elemental would float up into the clouds, but may not be able to control its movement.
• Fire elementals, in most ways, would work like earth elementals if they are attracted to the Earth's core. However, any fires in close proximity could rapidly change their gravitational "down". Forest fires, in particular, would drag lots of elementals in. And if someone wanted to trap a fire elemental, all they'd need is a big open space with a bonfire in the center, and a way to bait the elemental into the area. The elemental might try to "climb" out of the fire's gravitational "pit", but as long as there are no hand holds on the ground, it probably wouldn't be able to escape.
• That's not quite true for air elementals, shell theory should apply and they're within all the shells at sea level so they should in theory be based at sea level. Whether something similar applies to water elementals due to the relatively even distribution of water across the world I haven't yet worked out. Aug 5, 2016 at 10:31
• Shell theory assumes there's enough mass on the other side of the shell to provide a gravitational pull across the distance. With a thin enough shell over a large enough area, I don't know if the math still works out. That being said, I'm not a physicist, and the math is over my head. :) One thing I just realized, however, is that the density (and, therefore, buoyancy) of an air elemental would probably have at least as much influence on its "resting point". And if it can change its density, it would be able to relatively easily balloon its way up and down the atmosphere. Aug 5, 2016 at 11:21
• The great thing about shell theory is that it only requires the shell to be consistent and the maths all falls out quite neatly. Buoyancy and density would be its best way to control flight. Aug 5, 2016 at 11:36
• Updating my answer to reflect. :) Aug 5, 2016 at 11:40
• @PeterCordes Lol "It's probable with some fairly simple integral calculus." Aug 5, 2016 at 18:12

Do you mean a literal, physical attraction? Instead, perhaps consider instead a fascination/motivational attraction? (You'd get the same general effect, but you'd have more wiggle room with how strong it was, and when/why.)

If so, Fire might be fascinated by/attracted to industrial processes/factories that use high heats/lots of energy in one place: metal refineries (or at least forges), rocket engines, or even nuclear reactors/bombs!

I'm thinking about the 'Yags' (fire spirits) in Tim Powers' The Anubis Gates here. (Great book!) It's not exactly an always-unresistable force, but it does tug at them.

• Was thinking more primal something beyond their control or wants. so if it was attraction it would have to be like a vampire's attraction to blood Nov 29, 2016 at 9:40