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Gravity magic - How does it work?
(What physical law can magic manipulate in order to affect gravity?)
In my world everyone is capable of casting magic. It is possible for a single person to cast as many different types of magic as he/she wishes, assuming they know the spells. Every person also has an affinity to a specific type/form of magic, e.g. projectile magic, water magic or defensive magic. One of the main characters in my story has an affinity to gravity-based spells, so it is much easier and more intuitive to use them for her.
What I'm interested in is not how magic works in this context (assume there is some amount of recharging MP within every person that is used to cast spells), but rather how the gravitational effects caused by the magic could be explained.
I'm looking for a "generic" solution that explains explicitly this type of magic, not every single spell/usage, but rather "gravity-type magic" itself. I don't intend to explain my readers every single law of physics, space-time etc. in every detail, but the main aspect of "how" should come across.
When answering, take the following scenarios as use-cases for the magic to check:
- Slowing down yourself down when falling, so you don't hit the ground at full speed (as near to 0m/s as possible, at the very least you shouldn't be injured by landing) (e.g. jumping from higher up)
- Levitating yourself / other objects, so they don't move in any direction
- Bonus points: still won't move if influenced by another force (e.g. a thrown stone)
- Pushing objects out of your way (e.g. a locked door)
- Ability to combine multiple "gravity fields", so you could simultaneously keep a cup in place and rotate it upwards-down, while still keeping the liquid inside
I've also found the question How do I grant superheroes gravitational manipulation, justified scientifically?, but it is somewhat different than my question. My question focuses on how to actually perform the gravity-based magic and not on how you could justify the existence of such powers.
Edit: Thank you for all the great answers! I'll go with the Answer by Chronocidal, since it fits my own idea of how it should work best of the existing answers.