WHAT IS "PHYSICS" IN FICTION?"
In fiction, we write stories based on reality, to some extent or another. It can follow reality very closely, like in a normal, everyday, slice-of-life romance, or it can have magic, super science, or spirits. It can even be really out there, like Flatland, a book about 2-dimensional life, and have very little do to with the laws of reality, as we know it.
However, by definition, every fictional story has FICTIONAL physics, because the book is... duh... fiction. You, the author, have to decide what rules you are keeping, and what rules you are throwing out. For most, this is simple, since most authors don't change physics all that much. Less is more, so most stories have a few changes, stated up front, then the story tries to be "as normal" as possible from there. But maybe YOU are the exception.
I have developed a series of categories that I use for keeping my fictional setting's altered physics properly segregated so it is easier to keep track, thus avoiding emersion-breaking plot holes.
TERMS
Pataphysics - Imaginary Science (What we cannot conceive)
Metaphysics - Memetic Science (What we conceive)
Isophysics - Normal physics, but in the literary sense. (Objective reality)
Hypophysics - Quantum mechanics, but literary. (Subjective Reality)
Infraphysics - Null science (The science of nothing)
Paraphysics - An altered version of Meta, Iso, or Hypo.
EXAMPLES:
Pataphysics - Something completely alien to the human way of thought. This would be your neverborns or eldritch horrors of Lovecraftian origins. By definition, you cannot conceive Pataphysical concepts.
Metaphysics - This is thought. Pure concepts such as emotions, honor, philosophy, etc.
Para-metaphysics - It's where you take normal human thought and give it new rules that couldn't exist. The physical manifestation of thought would be a para-meta concept.
Isophysics - "Normal" physics, but the thing is, does "normal" physics really exist in writing? For example, 20 bad guys shoot SMGs at MC and nobody hits. This is Isophysics. Yes, it is POSSIBLE, but really, did that make sense? So, it isn't "physics", it's isophysics.
Para-Isophysics - You take physics and add new rules. This is most magic systems.
Hypophysics - Quantum mechanics, but again, literary. This gets a little fuzzy because TECHNICALLY, it should only be what is possible, but we don't actually know what is or isn't possible. On some level of reality, when you get small enough, perception changes reality. The act of observation alters what you observe. So this would be quantum mechanics as we understand it.
Para-Hypophysics - Quantum physics applied to macro objects. Again, this gets fuzzy. I personally put the line at "How hard is the Magic System/Super Science?" Para-Hypo is more sci-fi than Para-Iso, IMHO. It's more about how much justification you put into your altered physics. How closely do you "observe" your magic system? if you do a lot of hand waving, it's Para-iso. If you are very specific and detailed, chances are it should fall under para-hypo.
Infraphysics - The Science of NULL. This is a difficult concept to handle. It is the literary science of NOTHING. The absolute lowest end of concepts. Where we are dealing with the absence of everything. There might be a complete absence of matter/energy/thought, but even empty space has rules and permanence. So, if you are dealing with REALLY alien concepts about NOTHING, then you are dealing with Infraphysics.
You will note, that there are no Para versions of Pata or Infra physics. Why? Because it already IS as Para as we can get. There are no ALTERNATE versions of Pata or Infra physics because humans cannot even begin to conceptualize what is NORMAL for these versions of physics, much less what an alternate version of them would be.
IN PRACTICE:
Let's start with Isophysics:
You might say, why make up a new term? Just call it physics and be done with it. Why call it isophysics? Well, all isophysics falls under normal physics, but not all normal physics, falls under isophysics. What I mean is that isophysics are the rules of reality you, the author are KEEPING.
There was a new manga I read called Colorless. In this setting, it has most of the normal laws of physics. Buildings have foundations. People need to eat. Electricity works. That sort of this. All that would fall under isophysics. However, in this setting, there is no color, except for color that has been collected and harvested. This collected color has magical properties. So, under normal physics, there is a spectrum of color, but in this universe, there is not. The new and altered properties of color would fall under Para-Isophysics. Para-iso would be any normal laws of physics that you have changed or new laws that you have added. Typically, you would put most "normal" magic under para-iso.
However, if you are sticking with normal physics, but just pushing the boundary, it stays in Isophysics. Whenever you do something possible, but highly improbable, you should stick it under isophysics and keep an eye on it. Yes, luck exists, but if you use luck too much, it starts to move from isophysics to para-isophysics, and readers do not like it when you start making up powers on the fly to save your MC. It's a useful tool to keep track of "Possible, but improbable" events in your story. if you use them too much, you might want to consider going back to the start of the story and establishing that your MC is very lucky, or has a blessing from a leprechaun, or something, so it becomes easier for your reader to suspend disbelief.
Metaphysics:
Metaphysics is anything that deals with concepts. This is the realm of memes. If you can imagine it, it falls under metaphysics. We all know what thought is, so I hope I don't have to clarify that. However, you might want to get whacky with your memetics, so that becomes Para-metaphysics. Typically, that would be your ghosts, your spirits, gods, that sort of thing. If you want magic that is based off summoning spirits and then the spirits do the magic, that's Para-metaphysics. If your magic has personalities, it's Para-meta. So if you are just dealing with "hard" magic, you'd stick with para-iso, but if you are dealing with praying for spells, summoning spirits, that sort of thing, then you are moving into para-meta.
Now the two do bleed from one into the other. This isn't a hard and fast set of rules. Remember, this is to help YOU, the author, keep track of how you are altering your fictional setting and the changes you are making to reality. So, while a summoned spirit would be Para-meta, the magic it casts could fall under para-iso. It's useful to think of it this way, so that when you are considering "What can my MC do?" you don't make the mistake of making a given power a Swiss army knife. LIMITATIONS ARE GOOD.
People like to see MCs challenged and then overcome those challenges. They also don't like "new" powers that just 'happen' when the situation needs it. If you need the MC to get out of trouble, see if he has an already established ability you can twist and use in a devious manner to save his ass, rather than make something new, or if you must, make sure it's at least adjacent to an established exception.
Pataphysics:
I didn't make up the name. Some French guy did. This is the physics of what we cannot think of. If you can imagine it, it's metaphysics. If you can't, it's pataphysics. A good example of pataphysics is a 4-dimensional hypercube. We are three-dimensional. We cannot see in four dimensions, so we cannot truly "conceive" of a hypercube. We can make a 3-dimensional shadow of one, but in the end, we are just seeing its shadow and trying to imagine what it might look like
(Actually, because the back of our eyes is effectively "flat", we are seeing a 2-dimensional image of a three-dimensional shadow, of a four-dimensional object. Funny that.)
This is pataphysics in a nutshell. It is where you cannot conceive of something, but you can observe how such a thing might interact with what you CAN conceive. So if you are trying to write about truly alien concepts, then it falls under pataphysics. Oddly enough, a good chunk of horror stories use pataphysics. Most physics we can understand, but the utterly alien tends to send chills up one's spine. We can understand some guy chanting and casting fireballs. It's hard to understand why someone, with tears of bubbling pitch streaming down their face, would open three of their seven mouths to chant the song that destroys the world.
Both involve chanting, one is a bit more disturbing.
Pataphysics doesn't have to be terrifying, however. Look at Terry Pratchett's The Colour of Magic. Magic has a colour that we cannot see unless you are a magic user yourself. it is the 8th color. This would be Pataphysical. It's just a nice, yet alien touch to the story. I also like the part where he describes an object as being so cold it is ANTI-BOILING the water around it. So if you want to add just a pinch of the alien to your story, consider googling prefixes and suffixes and then take some concepts from your story and just mix and match. See what you can come up with.
Hypophysics:
Hypophysics is another word for quantum physics. Again, it is the physics you are keeping, hence why we use this term instead of quantum physics. Hypophysics is about the rules that govern very small things as well as minute details. When you try to observe very small objects, it gets increasingly difficult the smaller it is. For example, you need a microscope to see single-cell organisms. To go smaller, you might use an electron microscope. However, an electron microscope works by shooting a stream of electrons at an object. There is a limit to how small you can go with this.
Let's say you are trying to look at a single proton. If you used an electron microscope, this would be like trying to find out what color a beach ball is in a totally dark room by firing a stream of billard balls at it, then observing where the eight-ball bounced off to. This is what they mean when they say that the act of observing an object changes the object.
On a quantum level, perception changes the object you are looking at. If you took a stream of photons, trying to detect packets of energy, you will find packets of energy. if you switch to detecting for waves instead of particles, you will CHANGE the particles into waves. So if you have a stream of light that you split into two, and you start detecting for particles on one, and waves on the other, you will get 50% and 50% each. However, if you put a detector that detects only waves before the splitter, it will change the beam into 100% waves and you will stop detecting particles.
What's really strange, is that this can work in reverse, changing the photons retroactively one way or the other.
All sorts of strangeness occurs with quantum mechanics. Teleportation, tunneling, entanglement, and some REALLY strange stuff that seems to break the speed of light and conservation of matter and energy. However, it has limits. You can't walk through walls. You can't teleport a person.
But what if you COULD?
That's where Para-hypophysics comes in. If you are dealing with super-science instead of straight-up magic, then chances are you are dealing with para-hypophysics. When you want to break the speed of light, you might turn your MC into a macro-tachyon. You know what a sonic boom is, right? What if you want to break the light barrier? Would that be a "Luminal Boom"? What the hell would that even look like?
Para-hypophysics is like a scalpel, whereas Para-iso is more of a sledgehammer. The "science" of Star Trek is mostly straight-up magic when you think about it, but the writers (used to) put in a lot of effort to TRY and connect it to real-world physics. There is no reason you cannot mix and match. You see, while I'm mostly splitting it up by Fantasy being para-iso and Super Science being para-hypo, it's not quite that simple.
Para-hypo is more about how perception alters reality, and Para-iso is more about altered objective reality. A wizard just says, "By my will be done" and casts his spell. The scientist needs to justify what he is doing. He has to perceive how the magic works. He needs a full framework in his mind of all the steps. So a "hard" magic system would fall under Para-hypo, because you are getting down into the nitty gritty. Most very complex magic systems in a LitRPG would technically fall under para-hypo.
If you do a lot of hand-waving, or magic isn't that central to your story, you can keep most of it in Para-iso. However, if you plan on getting down into the details of how the system works, you are "Observing" it in great detail, then it's Para-hypo. Note, that this isn't a hard limit here. Again, these are just ways of keeping concepts subdivided so it is easier to keep track of how your setting works.
Infraphysics:
Finally, we get to the strangest of the categories. The physics of nothing. What is nothing? And I mean, Null, Not Zero, because zero is a number and therefore exists. I'm talking about Nul, where you don't even have a ZERO. What is empty space? Is the void actually something? If you had a box with a true vacuum in it, and no light or any form of radiation or bosons of any sort passed through, and you brought it down to absolute zero inside the box, is anything there?
Oddly enough, yes. If you could take something down to true absolute zero, the universe would force the temperature back up via virtual particles, thus creating energy. If you could keep harvesting it, you could achieve what is called, zero-point energy. Which is basically taking reality and dividing by zero and somehow getting a result.
Alas, since the conservation of matter and energy exists, you don't get it for free. What you are doing is converting reality into energy. Imagine that the world was on a grid, like most video games. You have to place things on the grid, or objects snap to the grid for placement. Zero Point energy would be like burning the grid ITSELF for fuel. In other words, using the very fabric of the universe for kindling. On paper, it sounds nice. I bet there would be some problems if we actually pulled it off.
If you are dealing with concepts like this, you are dealing with infraphysics. But it would also cover the use of "null" in general. Another example would be how you view magic working. In Forgotten Realms, magic works because of "The Weave", but the goddess Shar noticed that the weave left gaps. The weave casts a "shadow" between the threads of the weave. So the goddess of night used this "shadow weave" to set up an alternate power source for magic that allowed her to get around the goddess of magic's stranglehold on magic.
Perhaps you view magic as gathering mana and then releasing it. An alternate method might be to "dig a hole" in reality. To create a "mana vacuum" that then, due to thermodynamics, causes mana to flow into the "negative space", and thus a way of using the mana around you without "gathering" it. So if normal magic users gather magic into themselves and then use that to cast magic, this "vacuum magic" would be more about clawing a hole in reality, then stealing mana from sources around you to "fill up" the hole.
Infraphysics is a hard concept to tackle. It's basically the exact opposite of Pataphysics. At least pataphysics allows you to infer what you cannot conceive by observing how the inconceivable interacts with the conceivable. With infraphysics, you literally have NOTHING TO WORK WITH. It is more of "the edge of the map" than a concept that you would use for organizing the laws of your fictional setting, but if you are the sort who likes to play around with "Things Man Was Never Ment To Know", then this category is definately somewhere on your "To Do" list for things to play with.
CONCLUSION:
Think of these categories as just the way to order things so that when you are considering adding in a new power, or exception to the laws of physics, you can properly compare it to the other exceptions you have already added and say to yourself, "Does this add anything to the story, or is there a better way to do this? Have I changed too much, or does this fit in with what I'm doing?
For example, if your story is a romance where the magic system revolves around summoning sexy nymphs and fluttering faeries to cast spells and do magic, it wouldn't make much sense to have the Villain use laser blasters and robots. Now summoning spirits to shoot lightning bolts, or binding them into corpses to create an undead army, that fits much better.