Magic

On Arcania magic exist as just another set of laws of physics. It's a field, called the Aether field, that exists alongside for example the gravitational field or the electromagnetic field.

When you lit a flame, energy has to come from somewhere. In a wood fire, the wood provide the fuel. When a mage weave a fire magic, the energy for the fire is drawn from the Aether field.

Weaving magic deplete energy from the Aether field. Evolution gave creatures on Arcania means to make use of it. The humans calls them the Magic Channels.

Entropy is what fill the Aether field with energy. Entropy has many definitions, but can be thought as a unit of measure for disorder. A cold gas has the lowest possible energy state, and is fully disordered. A living creature is the opposite. An highly ordered arrangements of molecules at a very specific temperature.

In our universe, when energy is expended, some of it is wasted (converted in waste heat) the rest is converted in another form, doing it's intended work.

Think about a car's engine. Some of the fuel propel the car forward, but the rest of it is wasted in heating the engine up. We don't care about that heat, but it cannot be avoided. That's just how our universe work.

The most absolute law of physics, the Law of Conservation of Energy, state that energy cannot be destroyed, nor created. It can only be transformed. And there is a preferred direction. The universe want to go to a state of increasingly higher disorder, until eventually there is nothing but cold thin gas. The heat death of the universe.

On Arcania there is another set of law of physics that link entropy, energy and the aether field together into the phenomenon known as Magic.

In short, when work is done to increase entropy, some of the waste will not go into heat, but will fill the aether field. And the metabolism of a living creature is a prime mechanism for that.

Aether Ecosystem

As consequence, Magic can only exists where there is life. The more life, the more complex life is, the more the energy inside the aether field, and the greater the magic that can be weaved will be.

An aether ecosystem arise from life, just like there is an ecosystem based on food.

There are Aether producers. Algae, bacteria, plants, lesser animals. They have metabolism but don't use magic themselves. They constantly fill the aether field with energy.

Then the are Aether users. Like a mage weaving a magic, or bears that strengthen their muscles.

If the users become too many, the Aether field becomes depleted, and magic can't be cast. The users loses their advantage, and their numbers dwindle, until a point in which users and producers balance each others.