Especially in the mid-twentieth century, popular science fiction would often talk about "creatures from another dimension" and use similar language that suggested that a "dimension" refers to some kind of parallel or alternate universe. This usage is extremely different from the way that the term is used in actual mathematics, where "dimension" simply refers to the number of independent coordinates required to specify a location within an object. Loosely speaking, in the technical mathematical usage a "dimension" is more like a direction than a location. (It also doesn't really make any sense to talk about a being living "in" a particular dimension in the mathematical sense.)

How and when did "dimension" come to take on this connotation that seems completely unrelated to its actual technical meaning?

  • 2
    Have you encountered a book called Flatland?
    – Jim
    Jun 8, 2020 at 4:29
  • Einstein’s relativity introduced time as the fourth dimension. The popularization of this concept must have stimulated quite a few writers.
    – user205876
    Jun 8, 2020 at 14:43
  • 1
    Oxford has a dictionary of science fiction available in this dimension. HG Wells - 1896 - Plattner Storiy in New Review Brave New Words - 1953
    – Phil Sweet
    Jun 9, 2020 at 1:58
  • 1
    It's worth mentioning that this usage was not restricted to science fiction. It appears as a metaphor for anything unreachable from the ordinary 3D realm in nonfiction and ordinary fiction novels. And I found several examples in religious writings - The Son of Mary Bethel -1909
    – Phil Sweet
    Jun 9, 2020 at 2:14
  • 1
    @Dobob The question being asked here is when people started that trend.
    – Philipp
    Nov 21, 2022 at 16:03

4 Answers 4


It doesn't seem to have originated in science fiction, but in esotericism, at the end of the 19th century.

Ideas about additional dimensions were common in 19th century scientific literature, before manifesting in Edwin Abbott Abbott's Flatland in 1884. These were mathematical in nature, but could include the idea of hidden dimensions which might intrude upon us, as if from another place that we could not see. Section 16 of Flatland describes the arrival of a three-dimensional sphere which appears out of nowhere, manifesting to the Flatlanders as a circle.

At the time there was a growth in mystical movements including spiritism and theosophy as well as mystical trends in mainstream movements such as Roman Catholic mysticism. Both HP Blavatsky's The Secret Doctrine (1888) and P. D. Ouspensky's Tertium Organum (1912), suggested the existence of additional spiritual dimensions. Blavatsky used the concept of the fourth dimension but not as a literal spatial measurement so much as an alternative mode of existence separate from the merely physical, akin to the mental or spiritual. Similarly, in spiritism, there was an interest in the spirit realm as an alternative place populated by the souls of the dead. Hence we have a fourth dimension both as a different quality of matter (perhaps a spiritual or pantheistic quality), and as an alternative realm, a place from which we might be watched. Works such as Flatland suggest that the two-dimensional world might be embedded in a three-dimensional space where much happens that we never see, but which may sometimes intrude into our more limited world.

We also find from the late 19th century a lot of metaphors about beings watching or intruding from another dimension. This relates partly to the idea of a third dimension rising high up above the plane to offer a new view, but also links to mystical or spiritual ideas about other planes of being. For instance (from Google Books), Charles Webster Leadbeater's 1926 Clairvoyance speaks of beings "looking down upon the transaction from another dimension"; Higher Psychical Development: An Outline of the Secret Hindu Teachings by Hereward Carrington in 1920 says of his secrets "it would permit us to attain a higher view,- from another dimension,- which would allow us to look down". There were also common metaphors, found in Blavatsky and later, about reflections or shadows cast from other dimensions; see also the spiritist William Usborne Moore's 1913 The Voices.

Similar ideas can also be found in the Catholic mystic Evelyn Underhill's 1907 The Lost Word which mentions animals appearing: "They came up out of the dusk suddenly, stealthily, as fabulous creatures might creep on us from another dimension". Here we have the idea of beings arriving to us as a Flatlander might face a being intruding from the third dimension.

By about 1940, "another dimension"/"second dimension" and variants are common expressions referring to a different aspect or perspective - the OED ("dimension", 2.c) has its first citation from 1929.

I can't find any instances from science fiction until much later. But The UFO Evidence from the National Investigations Committee on Aerial Phenomena, edited ‎Richard Hall, 1964, mentions "saintly beings from space (or another dimension)". This shows a linkage of aliens and beings from another dimension.

You can find some of these topics discussed with reference to another 1920s mystic in "Where even the trees come and go": D. H. Lawrence and the fourth dimension, Richard O. Young, The D.H. Lawrence Review, Vol. 13, No. 1, D.H. Lawrence: Myth and Occult (spring 1980), pp. 30-44


Dimension was first used with the sense "parallel universe" in science-fiction by H. G. Wells who was a prominent English writer mainly known for his science fiction novels, and he has been called the father of science fiction. He first used dimension with this sense with the phrase fourth dimension referring to a parallel world in his science-fiction story The Plattner Story. This usage is an analogy to its original sense in maths and physics: "a supposed or assumed dimension, additional to length, breadth, and thickness". The earlier usages appears to be about what fourth dimension could be in addition to three dimensions (even in some science-fiction works); and not exactly referring to a parallel universe/world. Dimension was first used by itself referring to a parallel world in 1922, again by H. G. Wells, in the "science fantasy" novel Men Like Gods. Dimension is mostly used as "another dimension" in science fiction works referring to a parallel world or an 'unseen' world that we can't perceive, a semantic extension of the notion 'fourth dimension'.

Here is the definition and the three earliest citations from the book Brave New Words: The Oxford Dictionary of Science Fiction (by Jeff Prucher)*:

dimension n. a universe coexistent with our own, but which cannot be perceived or accessed by ordinary means and which often possesses different physical laws; an ALTERNATE REALITY or PARALLEL UNIVERSE. Also fig. Compare PLANE.

[1896 H.G. Wells Plattner Story in New Review (Apr.) 352: The curious inversion of Plattner’s right and left sides is proof that he has moved out of our space into what is called the Fourth Dimension and that he has returned again to our world.]

1922 H. G. Wells Men like Gods (1923) 22: And now he imagines himself in some sort of scientific romance and out of our world altogether. In another dimension.

1931 Wonder Stories (letter) (Mar.) 1193/1: I was told that there were many more such races in the universe, though in other dimensions.

  • 1
    "Dimensions" wasn't technically used in the sense of "parallel universe" by H.G. Wells and most early sci-fi authors. In these works, there is still some appreciation of dimensions as properties and not worlds or universes. Quoting from Men Like Gods, "Serpentine proceeded to explain that just as it would be possible for any number of practically two-dimensional universes..." Thus, H.G. Wells saw "dimensions" as separate from "universes". In more contemporary works, there is no appreciation for spatial or temporal dimensionality, and "new dimensions" are just other worlds or universes.
    – Dobob
    Nov 22, 2022 at 14:07
  • @Dobob It is true for the earlier works of H. G. Wells, and also he was using different senses of the word "dimension" in different works (and possibly, even within the same work). For example, he used "dimension" in his 1895 book The Time Machine but he didn't use it with the "parallel universe" sense. "Parallel universe" sense first appeared in his 1896 story Plattner Story and more concretely in his 1922 book Men Like Gods. Also, he may have used the word "dimensional" with different senses. The senses of the word "dimension" were overlapping around that time.
    – ermanen
    Nov 22, 2022 at 21:45

The mathematical reason for how parallel universes exist is obviously complicated, so people referring to "dimensions" as an alternative of "parallel universes", "realms", "other worlds", and the like, seems to be doing so out of confusion and improper research. Unfortunately, this usage proved contagious and has become a trope, so now seemingly every sci-fi and fantasy author believes that "dimensions" means "other worlds". Let's discuss some factors that might have led to this confusion.

Types of multiverses

There are many theories on how parallel universes can exist, and these two are some of the most popular in my opinion:

  1. Brane cosmology from string theory:

The brane multiverse version postulates that our entire universe exists on a membrane (brane) which floats in a higher dimension or "bulk". In this bulk, there are other membranes with their own universes. These universes can interact with one another, and when they collide, the violence and energy produced is more than enough to give rise to a big bang. The branes float or drift near each other in the bulk, and every few trillion years, attracted by gravity or some other force we do not understand, collide and bang into each other. This repeated contact gives rise to multiple or "cyclic" big bangs. This particular hypothesis falls under the string theory umbrella as it requires extra spatial dimensions.

  1. Many Worlds Interpretation of quantum mechanics (arguably the most popular, but has nothing to do with higher dimensions on its own):

The quantum multiverse creates a new universe when a diversion in events occurs, as in the real-worlds variant of the many-worlds interpretation of quantum mechanics.

Types of multiverses: https://en.wikipedia.org/wiki/Multiverse#Types

Brane cosmology is a relatively new theory (first documented application in 1983) and might not be the main cause of the confusion between "dimensions" and "worlds", but it is directly related to a type of multiverse that has inspired more recent literature on parallel universes. Going further back in time, the cosmology of Einstein's General Theory of Relativity (1916) proposed a higher fourth dimension, which likely inspired earlier authors. However, the reasoning may be the same, in that writers may conjecture, however romantic, that entities may travel to parallel universes via a "path" through higher dimensions. E.g., the fantastical act of a flatlander in a 2D world jumping to a different 2D world via the third dimension like a drawn stick figure jumping off his home paper on your desk and over to the next paper (however that would look or work). At least this conjecture offers some sense of mechanics and attempts to distinguish "dimensions" from "other worlds", and that "dimensions" was a property of those worlds and not those worlds itself. I.e., a 3D world is still just a world and not "a dimension". But, as we know now, the term "dimensions" has been bastardized further to become these other worlds itself, and not "mediums" or "paths" to them. The reason for this may be because when people heard that a flatlander traveled through the "third dimension", people thought of the third dimension as a world. People also heard how the flatlanders lived in the "second dimension", which is also thought of as a world. But the problem with this usage is the conflation of property of that world, its dimensionality, and the world itself. The third dimension isn't a "world", but a property of worlds. E.g., the two separate pieces of paper that a flatlander can live in are two different worlds sharing the property of two-dimensionality. Or in the Many World Interpretation, the universe where the cat is dead and the universe where the cat is alive in the Schrodinger's cat thought experiment are two different universes having the same dimensions. Sci-fi literature that do make attempts to distinguish "dimensions" from "worlds" still often contain potentially confusing passages that conflated "dimension" and "world" (for an example, see an excerpt from an article in a later section of this comment). So, it's not difficult to see how people naturally started to think "dimensions" equals "worlds".

Paths through higher dimensions in literature: https://en.wikipedia.org/wiki/Fourth_dimension_in_literature


It was difficult finding a resource directly answering the question, and perhaps this is why people continue to confuse the terminology, which is also the reason I decided to make this post. There is an article from the University of Texas physics department saying that popular pseudoscience may have a hand in the confusion of terminology (it's worth reading the whole article for a short historical understanding of how physicists or mathematicians actually use "dimensions"):

Beginning in the last decade of the 19th Century, newspapers and magazines were full of completely confused accounts of "the fourth dimension," not to mention "vibrations" and "energy," two hot topics of late 19th Century physics. When Einstein came along, the "fourth dimension" became an even hotter topic, and acquired some curves too. Higher dimensions in pseudoscience are often even further confused with then-unrelated scenarios, such as "coexistent worlds," "parallel worlds," the "worlds" reached in dreams and drug-visions, not to mention Heaven, Hell, and even other planets. Mindless journalistic publicity for string theories has over the past two decades touched off yet another wave of science-fictional and fantastical delirium involving "multiple universes," a delirium owing a lot to late 19th Century Theosophy, but essentially nothing whatsoever to advances in physics.

Higher dimension pseudoscience: https://web2.ph.utexas.edu/~coker2/index.files/4d.shtml

Spiritual Dimensions

There is also a usage of "dimension" in the term "spiritual dimension", which has nothing to do with "parallel universes", "worlds", "realms", or the like. Spiritual dimension are the dimensions of the mind. E.g., dimensions of 3D space is length, width, and height, but the dimensions of spirituality might be "consciousness", "purpose", "meaning of life", or the like. I was compelled to add this here because Merriam Webster's fifth definition of "dimension" is "a level of existence or consciousness", referring to the spiritual dimensions. But I can see how someone may be confused and take "level of existence" to mean other worlds.

Spiritual dimensions: https://pubmed.ncbi.nlm.nih.gov/8550306/

Merriam Webster definition: https://www.merriam-webster.com/dictionary/dimension

When Was The First Usage?

It is likely owed to no single author in popularizing the wrong usage. As for first usage, a lot of the older, shorter literature is lost, so I can only make an approximation. Algernon Blackwood's "The Pikestaffe Case" (1924) was the earliest sci-fi story I found where "dimensions" referred to worlds.

So this mathematics professor ("Mr. Thorley is a high mathematician. He makes measurements and calculations") who reads "Gauss! Minkowski! Lobatchewski! Einstein!" takes up lodging at an old woman's guest-house and starts performing some experiments with an antique mirror in the house (going so far as to order "mathematical instruments"). Then, one day, he disappears and so does his best math student, Gerald Pikestaffe. The old lady sees them hovering in some new dimension inside the mirror, faints and later, predictably, the mirror breaks and all links are lost.

I also found an article in a "Wonder Stories" magazine from 1931 that seemed to have the usage that dimensions are mediums or paths through worlds or time, or that extra dimensions are some property of reality overlapping the current universe that cannot be observed by humans, but which a latter usage in the same story could be interpreted by the reader as "dimensions" being "worlds".

There was also another race on Earth which was not human but equivalent in every way to man, though utterly different from mankind in its aims, makeup and development. I could not quite make them out as they were absolutely beyond my experience. But I was told that there were many more such races in the universe, though in other dimensions.

The passage technically distinguishes between "dimensions" and "universes", but instead of "universes", it still implies there is some magical realm overlapping the current universe as a separate world. The way it says "in other dimensions" effectively conflates this magical realm with the term "dimensions". Despite this, neither of those works were probably as impactful as later works by the likes of H.P. Lovecraft's which used "dimensions" to refer to "worlds" or "realms", such as in the following passage from Lovecraft's "Dreams in the Witch House" (1933):

...for who could foretell the conditions pervading an adjacent but normally inaccessible dimension.

Here, Lovecraft directly referred to the property of dimensionality as a world that can be accessed, thus conflating the world itself with the dimensionality of that world.

Whether or not these authors themselves knew that "dimensions" did not mean worlds, the confusing usage of "dimensions" in these earlier works likely influenced later authors' treatment of the word "dimensions" as entirely other worlds. E.g., in Cassandra Clare's "The Mortal Instruments", dimensions basically mean "other worlds" and demons come from the "hell dimension", and thus here, the notion of dimensionality as a property is entirely lost.

Further reading:




In conclusion, "dimensions" still means the axes in a coordinate system. But unfortunately, due to earlier confusing usages predominantly in sci-fi and fantasy writing, "dimensions" seems to have become an acceptable stand-in for other worlds, universes, or realms in the sci-fi and fantasy sub-genre (I pray it doesn't spread elsewhere). It is a pet peeve of mine whenever I come across "dimensions" in a sentence when what they're really trying to say is "other worlds", and I hope writers begin to move away from such usage.

  • 1
    Thanks, but I was more looking for the specific history of exactly when the word first began to be used in English-language fiction and in what context (i.e. specific first uses).
    – tparker
    Nov 21, 2022 at 14:26
  • 2
    This is all really interesting, but doesn't answer the question. Remember that this is English Language Stack Exchange, not Physics Stack Exchange. Whether or not calling parallel universes "other dimensions" is scientifically accurate is only of secondary concern here.
    – Philipp
    Nov 21, 2022 at 15:58
  • 2
    @tparker, it is likely owed to no single author in popularizing the wrong usage. Algernon Blackwood's "The Pikestaffe Case" (1924) was the earliest sci-fi story I found where "dimensions" referred to worlds. I was also able to find an article in a magazine from 1931 that seemed to have the "correct" usage, but which a latter usage in the same story could be interpreted by the reader as "dimensions" being "worlds". Further resources: sf-encyclopedia.com/entry/dimensions sfdictionary.com/view/1241/dimension
    – Dobob
    Nov 21, 2022 at 16:05
  • 2
    Great, that's what should be the central point of your answer, not just hidden in its comments.
    – Philipp
    Nov 21, 2022 at 16:06
  • This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. - From Review
    – jimm101
    Nov 21, 2022 at 16:12

As mentioned in the comments, Science Fiction writers, led by the mathematician Charles Howard Hinton, explored the consequences of the fact that the mathematical theory of space can be extended to dimensions of number greater than the 3 we see around us. If one could "access", "manipulate" or "travel" in a fourth dimension, i.e. one independent of the three we can directly experience, you would be moving through a form of space which is exactly like what we mean by "parallel universe" - as people in the 'regular' universe would be unable to witness any changes that took place there, and yet 'real' physical interactions and experiences could happen solely in that extra dimension. A good way of accessing an intuition about this is imagine if everything that went on in a room was projected onto a wall - say an observer is outside a marquee or tent and sees the shadows on the wall. Then if people move toward or away from the wall the observer won't see (much of)* a change, so any interactions that happen in that dimension - the dimension perpendicular to the wall - happen in a world inaccessible to the observer - just like being in a 'parallel universe'.

It's fascinating that this question has come up as within the last couple of weeks I have read both a review of a novel about Hinton https://www.theguardian.com/books/2020/apr/23/hinton-by-mark-blacklock-review-voyages-into-the-fourth-dimension and an article by the author of that novel about the fourth dimesnion in science fiction https://www.theguardian.com/books/2020/jun/03/top-10-four-dimensional-novels-mark-blacklock-hinton.

  • the 'projection' in this real-life example doesn't work like a perfect mathematical projection, but I hope you still see the point
  • This doesn't explain the use of dimension to mean parallel universe. The definition you mentioned still refers to spatial dimensions, not parallel universes. The reason I presume that most likely explains the erroneous adoption of "dimension" as an alternative of "parallel universe" is simply that no one bothered to check what the word meant before using it because they remembered it being used in such a way by some accomplished author and therefore believed it is the correct usage. I've seen people use "dimensions" as an alternative of "parallel universe", until I showed them the dictionary.
    – Dobob
    Nov 21, 2022 at 10:21
  • @Dobob I'm afraid I have to disagree. Let's cut it down to the most basic - suppose our universe, instead of being 3-dimensional, was 1-dimensional, i.e. it was a straight line. Imagine also that you have access to 2 dimensions - a plane - and you can see the line that is our universe running along this plane. You could also see universes just like our own - also straight lines - running parallel to, and never intersecting with ours, in the plane.
    – Judy N.
    Nov 21, 2022 at 15:21
  • 3
    This is all really interesting, but doesn't answer the question. Remember that this is English Language Stack Exchange, not Physics Stack Exchange. The question being asked here is "since when do people refer to parallel universes as other dimensions". Whether or not that's scientifically accurate is only of secondary concern here.
    – Philipp
    Nov 21, 2022 at 15:59
  • @JudyN. What you are explaining is the dimensionality, i.e. a property, of those worlds, not the definition of the word "dimension" itself. A theoretical "world" can have any dimensions. A 3-dimensional world is a world and not "a dimension". The question asked why and how "dimensions" has popularly become synonymous to "worlds".
    – Dobob
    Nov 22, 2022 at 7:47

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