Could anyone offer some hypothetical ways in which gravity could be used to fuel magic by those that "know"?

I'm writing a story in which a few characters are in said know, and utilize gravity as fuel for their magical spells. Some spells are extreme speed and materialize a sword by forming a liquid formed metal into a solid (using gravity). I'm not great with math and specifics of how gravity works and am curious if there is any "reality" or at least plausible explanations for how something like this might work.


Several replies have helped, but I'll try to clarify what I'm thinking about. It may make even less sense but I'll give it a shot.

I have one character who has magical abilities. My thought is that he draws on gravitational force to fuel those powers via a resource (liquid that he has knowledge of, kind of like a potion). My question is really to see if pulling on say earths gravitational force would be too much/too little? He could obviously take more/less if he had control but I'm curious what kind of power that could potentially be as I don't understand the strength of gravitational force besides the obvious in real world application. My goal is to try and incorporate some sort of explanation for his ability to do the things he can do as magic is not a part of the world except in myth.

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    $\begingroup$ You can't just 'get' energy from gravitational fields. Because the next thing people usually turn to the the Earth's magnetic field, you also cannot just 'get' energy from the Earth's magnetic field. $\endgroup$ – ifly6 Dec 31 '16 at 14:49
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    $\begingroup$ The wizard holds a brick over the unsuspecting foe's head. *klonk* magic. "Never rely on gravity magic, when a brick will do." $\endgroup$ – Cort Ammon Dec 31 '16 at 16:32
  • $\begingroup$ Technically we already harness gravitational energy. The energy collected from waterfalls/dams is gravitational energy. $\endgroup$ – Clangorous Chimera Dec 31 '16 at 17:00
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    $\begingroup$ All kidding aside, have you read Sanderson's First Law of Magic: "An author’s ability to solve conflict with magic is DIRECTLY PROPORTIONAL to how well the reader understands said magic." Is your goal of "explaining" magic with a non-scientific expansion to a scientific force assisting you towards helping the reader understand your magic? If so, it may help to edit that into the question. Otherwise, you may make your life easier by not explaining the connection at all (or not even making the connection in the first place). $\endgroup$ – Cort Ammon Dec 31 '16 at 17:03
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    $\begingroup$ Also, if I may plug my own answer, my answer to The smallest change to physics needed to permit magic may be applicable by showing just how fine the line between physics and magic can be if you permit it to be. $\endgroup$ – Cort Ammon Dec 31 '16 at 17:04

It's magic. There's not supposed to be a plausible explanation.

With that disclaimer out of the way, gravity is a force. A force does work, which is energy over time. In a non scientific way "energy is what is required to do anything." Once you have energy, it's just a matter of the mechanism for turning into another form of energy (changing the speed of an object) or matter ($\text{E} = \text{mc}^2$ - energy and matter are basally the same.)

The mechanisms are were you have to hand wave. If you don't, it stops being magic and starts being science fiction.

Let's look an a possible explanation for your science backed magic:

Special sub atomic particles called Magicions exist but are undetectable if you're not "in the know". Magicons are abundant in the universe, and have mass. The force of gravity acts on the Magicons' mass and makes them fall, giving them energy. (This flavor of magic won't work well in deep space.) Your magic users have a biological mutation that allows them to 'feed' on the energy of the falling Magicons, perhaps like mechanisms in our stomach and blood allow us to feed of the chemical energy in food.

Now that you have the energy to fuel your magic, you just have to invent another mechanism to transfer the energy into whatever you want. This is fiction, and you're apparently writing a fantasy novel. Make up whatever you want.

Basically, under the conservation of energy, if could be possible to extract the energy for magical activity from gravity, as long as you have some object/s with mass to turn that the force of gravity into energy as an intermediate stage.

  • $\begingroup$ Very helpful, thank you. I do understand that it's magic and doesn't need explanation really, but my goal is to have some idea of how my magic is working even if I don't explain it in story. I believe that might help me when i'm deciding what it can and can not do in certain situations. My world is medieval design with some mechanical advancements you wouldn't typically find. Sort of steampunkish. Limited advancements for the sake of my plot but extra gadgets and daily/quality of life things you wouldn't see in a typical medieval setting. $\endgroup$ – Benjamin Jan 2 '17 at 14:52

What you're trying to do is have a form of magic explained by 'magic'. the trouble is that science-based magic while it can be fascinating and marvellous beyond belief it isn't as magical as magic (or what we imagine is magic).

To make this work it will be necessary to assume there is a completely inexplicable mechanism for drawing on gravity to power a wide variety of magic spells. Let's assume that the Earth's gravitational field acts as an energy battery that can be used to power magic.

The gravitational binding energy of Earth, EGB = $\small 2.4 × 10^{32}$ J.

This is a massive amount of energy. More than enough to power a considerable quantity of magic spells. Tapping into this much energy should easily enable liquid metal to be formed into a solid sword or power extreme speed.

The real magic with this model of magic is that the 'magic' to make the magic work remains 'magical' in the sense that it's not necessary to explain how it works. Stage magicians never explain their tricks. Writers should do the same thing. They should only explain as much as the reader needs to know to believe what is happening in the story can happen (this is irrespective of whether it could really happen in the real world) in the story.

There might be effects a more scientifically minded person might worry about, like whether the Earth's gravitational field might weaken ever so slightly while this gravity based magic is working its spells. Or if the Earth's orbit might widen as our planet moves an infinitesimal distance further from the Sun. Please ignore Mr Science standing behind the curtain, he's not needed for your story. Remember, always, it's magic!

  • $\begingroup$ This helps me a great deal thank you. What I was really looking to get was HOW MUCH power I was looking at when going to gravitational force for the fuel or source. I am not sure yet if I intend on explaining it all but I did want some reference point for myself when deciding what I can and can not do with the magic. $\endgroup$ – Benjamin Jan 2 '17 at 14:54

I have a great idea. ER=EPR is one of the hottest scientific ideas in physics right now. Entanglement of empty space “stiches together” space. Look at Susskind’s videos explaining it.

The other thing, kind of “trendy” right now is the idea of entropic gravity. While the specific hot new report concerns a specific idea that (regardless of how popular press esplains it) does not match our actual universe, it is clear that there is some deep connection between gravity and thermodynamics.

You can use that as a starting point. Gravity emerges from more fundimental laws of causality and spacetime recordkeeping. Hacking that, messing up the natural structure, has a side effect of destroying the operation of gravity.


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