EXTRACT FROM THE SEMINAR "AN INTRODUCTION TO DIMENSIONALISM" PRESENTED BY GRAND MAGE GLEN FJÖLMER AT THE SCIENTIAN ACADEMY OF THAUMATURGY
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"...Alright, before we dive in, let me make one thing very clear: what I’m about to introduce you to is not—and I repeat—not the definitive model of reality. The cosmos, as we know, is just far too complex for anyone—or anything, really—to fully grasp. That said, there are a number of models out there that try to explain how our reality works, but today I’m only going to talk about the Realmistic Cosmos Model. This model was developed by The Third Sage herself—yes, that Third Sage—and it’s the one most of us agree on as a baseline for understanding the structure of reality.
So, what does this model say? In short: reality is made up of three layers—Planes, Dimensions, and Realms. Each layer builds on the last, and together they create what we call our universe—or, well, multiverse, depending on how you look at it.
Let’s start with Planes. According to the model, a Plane is any single, infinite space that you can move around in continuously without needing things like Gates, slips, portals, no matter if they're natural or man-made. If you can walk, fly, or swim your way through it without jumping to another space, it’s a Plane. Some well-known examples would be the Plane of Shadow, the Ashwastes, or the Faelays.
But, not all planes are infinite, and that’s where it gets interesting. There are actually a two more different types of planes:
Demiplanes: These are finite. You can still move around continuously in them, but they have boundaries. Think of a pocket plane, which can be as small as, well, a pocket—or as massive as a mountain or even a planet. Some are artificially created with dimensional magic, but others just appear naturally.
Quasiplanes: Now, these are a bit of a headache. A quasiplane is a plane that we haven’t quite figured out yet. We don’t know if it’s infinite or finite, so we just call it a quasiplane until someone smarter—or luckier—comes along to prove otherwise.
Stolen from Royal Road, this story should be reported if encountered on Amazon.
Next up: Dimensions. These are collections of planes—three or more, typically—that all follow the same fundamental rules or laws of physics.
For instance, take our own Temaerian Dimension. It’s made up of multiple planes, but they all operate under the same basic set of rules. Now compare that to the Elemental Dimensions—like, say, the Plane of Fire or the Plane of Water. The rules there are different, but consistent within their own dimension.
Also, remember that a single plane can exist in more than one dimension. Yeah, I know, it’s weird. It’s like being part of two clubs at once, and the clubs don’t even have to be in the same continent.
How we figure out which plane belongs to which dimension? That’s... a topic for another day, or we’ll be here all night.
Finally, we’ve got Realms. A Realm is basically a collection of dimensions that share overarching similarities. Think of it as the big picture.
To make it easier, let’s use an analogy—my old dimensionalism professor loved this one. Imagine a house.
The floors of the house are dimensions. They’re separate, distinct, but they all follow the same basic structure—like the same architecture.
The rooms on each floor are planes. They’re all unique, but they fit into the “style” of their respective floor.
And the house itself? That’s the realm. It holds everything together under one big, shared set of rules.
Now, before you run with this analogy, let me say this: it’s very simplified. Realms are not neat little floors stacked on top of each other. They’re fifth-dimensional constructs made up of, a sometimes literally, uncountable number of fourth dimensional dimensions, which are in and of themselves made up a potentially infinite number of third-dimensional planes—many of which are infinite. And don't even get me started on the potential rules and laws of physics that govern them. They can all slightly differ, yet somehow all allow for their own type of magic that is more often than not, not even based in mana. I mean just take a look at the Faerie. It is eerily similar to our own dimension, close enough for a human to live out there whole lives there, without any significant side effects. Yet still different enough to have its own entirely different magic which is just as, if not more complex than our own!
...Ahem, got a little side tracked there. Anyway, The point is: this is just an introduction. If you walk away from this lecture with even a basic understanding of planes, dimensions, and realms, I’ll call that a win. There’s a lot more to it, of course, but we all have to start somewhere.
Alright, let’s move on..."