I'm trying to trying to world build a high fantasy and sci-fi. But I can't differentiate the difference between the plane, dimensions, realms and realities. So, I want to know what the difference between them and how and why they are different.

Edit: I know this is nothing much because its my first time but my cosmology is like this • The Omniverse. It contains the totality of all creation and beyond. • The Nigh-Omniverses or Verses. It contains infinite megaverses. The number of nigh-omniverses is infinite. They never ever interfere with each other or possible to interact with each others. • Megaverses. Its contains infinite number of multiverse. • Multiveses. Its contains finite of universes. • Universes. Self explanatory.


closed as primarily opinion-based by JBH, Renan, Vincent, Cyn, Gryphon Dec 30 '18 at 18:36

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    $\begingroup$ Have you considered Scifi.SE or Writing.SE? While we can answer the question, it really isn't in the scope of this site $\endgroup$ – nzaman Dec 30 '18 at 16:32
  • $\begingroup$ @nzaman are they any different ? $\endgroup$ – Xeno Dec 30 '18 at 16:34
  • $\begingroup$ As the names suggest, one is for questions related to science fiction and fantasy, including the associated concepts, the other is about professional writing $\endgroup$ – nzaman Dec 30 '18 at 16:37
  • $\begingroup$ @nzaman I see thanks i will go there then. $\endgroup$ – Xeno Dec 30 '18 at 16:38
  • $\begingroup$ I actually think Worldbuilding is the right forum. SciFi/F seems to be more about the literature of those genres, whereas this question seems to be more about applying a concept to a secondary world. $\endgroup$ – elemtilas Dec 30 '18 at 16:47

A lot of works use these terms interchangeably, though they have distinct meanings in reality.

A "plane" is technically a flat, two-dimensional surface, but in fiction this is used metaphorically: imagine reality as a whole to be a 3-D "space" with a bunch of 2-D "planes" layered on top of each other. Objects on one plane can interact with objects on the same plane, but not with objects on another, but it is possible for some entities to move between them or even extend across them. In fantasy this is used as an analogy to imagine 3-D "planes" layered "on top of each other" in 4-D "space". It can mean that each location in one plane corresponds to a specific location in another plane, but this is not always the case.

"Dimension" is basically always used wrong in this sense. A dimension is technically a pair of opposite directions: Length is the first dimension, width is the second, height is the third. (Ignore "time" for now; while "time" is dimension-like in some ways it works differently in practice.) Now imagine a fourth spatial dimension perpendicular to the other three. By traveling along that dimension, one might wind up in another 3-D space (same concept as the "planes" metaphor). So you're not really traveling to "another dimension", you are traveling through another dimension (direction) to reach an inaccessible place. But fiction writers often use "another dimension" to mean "another universe" anyway.

"Realm" literally means "a kingdom". It is much more common to use this in fantasy works where each region of existence is ruled over by its own god or cosmic entity or something; you'll rarely see this used in more scientifically-flavored works but it works well to give your work a more mystical flavor.

"Reality" suggests an additional layer of division between the worlds, it's not just an inaccessible place you can only arrive at by traveling along a fourth dimension, but rather from the perspective of one world the other world isn't even real. You'll find this when crossing over to mutually-exclusive continuities, or where the basic "rules" governing that reality are different from one to the next.

But...in reality, people just use these terms however they feel like. I'd advise against using "realm" in sci-fi works, and not to use "dimension" to refer to a universe at all, despite the fact that many writers do. If you want to be clever and modern, you can use "brane" - this is the term string theorists use to describe cosmic "spaces" regardless of dimensions involved. Brane is short for "membrane", evoking the same basic imagery as "plane" above.

  • $\begingroup$ I was gonna answer along these lines. +1, specially for "people just use these terms however they feel like". $\endgroup$ – Renan Dec 30 '18 at 17:35
  • $\begingroup$ ok that helped actually. $\endgroup$ – Xeno Dec 30 '18 at 22:14

In my experience (as reader of sci-fi, fantasy, etc. and also as maker & writer), I view these four words as "roughly equivalent concepts". There is a distinction without a difference about them, and the distinction really boils down to genre.

First, dimension. This is an actual, honest to God science word. It has to do with how many coordinates are required to specify a point's location in space, time, etc. See this article.

Plane is often used in more paranormal & new agey spiritual contexts --- a "plane of existence". (Esoteric planes)

Realm and reality I've seen often with a more spiritual or cosmic understanding.

Sphere is also a good one to add to the armamentarium. It hearkens back to the music of the spheres and the hierarchy of spiritual realms.

Ultimately, for the purpose of worldbuilding, their specific meanings & usages often conflate and will vary depending on the nature of the world you are constructing. For a high fantasy & sci-fi world I might prefer "realm" & "dimension". For a more speculative soft sci-fi, I might choose "plane". For my own world (possibly closer to high-fantasy ?) I use "realm" and "hidden land" for these concepts.

  • $\begingroup$ In high fantasy, the word dimension need not carry its modern scientific definition. Terry Pratchett's Discworld was constantly under threat from the Dungeon Dimension, which had nothing at all to do with a coordinate. Indeed, he treated it (and other locations) more like parallel universes - but even that's wrong if you use modern science's definitions. This question's a hair unanswerable. $\endgroup$ – JBH Dec 30 '18 at 17:24
  • $\begingroup$ @JBH -- True. Mind you, what I wrote is not "hard and fast rules" so much as observations. Kind of out of scope for the question, but I think it could be argued that "Dungeon Dimensions" do indeed have to do with coordinates. They are simply places outside the ordinarily experienced dimensions.Same for alternate & parallel universes. I personally would leave "dimension" to the (hard) SF genre as a more purely scientific definition would fit better. Writer's choice (and I wouldn't be surprised if PTerry chose that as an alliteratve pun of sorts on D&D. What makes it unansw., in your opinion? $\endgroup$ – elemtilas Dec 30 '18 at 21:36
  • $\begingroup$ What makes it unanswerable is that, from the perspective of fantasy those four words are synonyms. They're all used to describe someplace "not here" that's accessible via spell, gate, portal, or some other means. In that regard, they are at best a means of categorizing a particular type of "not here" per any author's needs. Without having a fairly detailed description of those needs, there isn't a way we can recommend using one word to mean anything the others cannot or should not. $\endgroup$ – JBH Dec 30 '18 at 23:14

Aren't (good) dictionaries wonderful?

I'm rarely in favor of quoting dictionaries, but this is one of those few occasions when such an action is warranted.

The words plane, dimension, realm and reality are all polysemantic (meaning that they have multiple meanings). The following extracts from the Oxford English Dictionary (OED), 2nd edition with additions, 1997, and the English Wiktionary give the senses recorded in those dictionaries which I consider relevant to the question; I have also included extracts from the on-line American Heritage Dictionary (AHD) when they seemed to add something:

dimension (from Latin dimensio, "(act of) measurement, size"; primary meaning is nowadays "measurable spatial extent, such as length, area, or volume"):

  • (OED, sense 3) a. A mode of linear measurement, magnitude, or extension, in a particular direction; usually as co-existing with similar measurements or extensions in other directions. [...] c. [after French dimension] The power to which any one of the fundamental quantities or units is raised in the expression defining a derived quantity or unit in terms of them; also (in pl.), all the fundamental quantities in such an expression, each raised to its appropriate power, which together show how the unit of the derived quantity depends on the fundamental units; method of dimensions, dimensional analysis.

  • (English Wiktionary, sense 4) The number of independent coordinates needed to specify uniquely the location of a point in a space; also, any of such independent coordinates.

  • (English Wiktionary; sense 6) One of the physical properties that are regarded as fundamental measures of a physical quantity, such as mass, length and time.

  • (English Wiktionary; sense 8) (science fiction, fantasy) An alternative universe or plane of existence.

  • (AHD, sense 4) (Mathematics) a. The least number of independent coordinates required to specify uniquely the points in a space. b. The range of such a coordinate.

  • (AHD, sense 5) (Physics) A physical property, such as mass, distance, time, or a combination thereof, regarded as a fundamental measure of a physical quantity.

  • (AHD, sense 6) A realm of existence, as in a work of fiction, that is physically separate from another such realm.

plane (from Latin planum; primary meaning is "flat surface"):

  • (OED, s.v. plane n.³, sense 4) (fig.) (from a horizontal plane n.³ in sense 1) in reference to immaterial things, as thought, knowledge, moral qualities, social rank, etc.: Higher or lower level, grade, degree. spec. in Theosophy.

  • (English Wiktionary, sense 3) A level of existence or development. (e.g., astral plane)

reality (from Neo-Latin realitas, "thinginess", "the quality of being a thing", derived from res, "thing"; primary meaning is "real (as opposed to imaginary) existence"):

  • (OED, sense 3.a) Real existence; what is real; the aggregate of real things or existences; that which underlies and is the truth of appearances or phenomena.

  • (English Wiktionary, sense 3) The entirety of all that is real.

  • (AHD, sense 3) The totality of all things possessing actuality, existence, or essence.

realm (from Old French realme, ultimately from Latin rex, "king"; primary meaning is "kingdom"):

  • (OED, sense 2) (transf. and fig.) a. The kingdom of heaven, or of God. b. Any sphere or region. (Sometimes with suggestion of a ruling power.) c. The sphere, domain, or province of some quality, state, or other abstract conception.

  • (English Wiktionary; sense 1) An abstract sphere of influence, real or imagined.

  • (English Wiktionary; sense 2) The domain of a certain abstraction.

  • (English Wiktionary; sense 5) (fantasy, role-playing games) An otherworldly dimension or domain — magical, ethereal, or otherwise — usually in reference to one ruled or created by a mystical character.


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