What Other Galaxies?

When "the Galaxy" and "the Universe" are used interchangeably, either in the logic of the plot or explicitly.

Since Tropes Are Flexible, it extends to particular planetary systems and even the Earth. In a similar vein, this trope also applies if galaxies other than the main one are treated as if they were a separate universe. In other words, made to be a Planet of Hats instead of a Multicultural Alien Planet like the main galaxy.

Sub-trope of Sci-Fi Writers Have No Sense of Scale. Related to Everything in Space Is a Galaxy, when the term "galaxy" is misused. Contrast with Small Universe After All. Compare with The Milky Way Is the Only Way when, despite the narrative acknowledging an outer universe, it's not traveled to; and with Corralled Cosmos, when there's an In-Universe reason why the characters can't travel outside a given parcel of the cosmos. An extreme (sometimes in-universe) form of Creator Provincialism.

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Examples:

Comic Books

• Marvel Universe: The Milky Way is by far the primary setting, to the point that the Multiverses are those born from variations of the Milky Way (the Earth, specifically). There have been multiple allusions to other galaxies but it's more to add hype to the big three galactic empires (Shi'ar, Kree, and Skrull) than anything else.
  • Galactus is almost always found looking for food in the Milky Way Galaxy, despite the billions of other edible planets elsewhere.
  • Guardians of the Galaxy
    • The Guardians of the Galaxy do this just by name alone, both original and modern since their remit is protecting the entire universe (whenever they can). Enforced because "Guardians of the Universe" was already taken by Green Lantern.
    • Gamora is often called the Deadliest Woman in the Galaxy. Never mind there exist galaxies besides the Milky Way, galaxies with maybe their own deadliest women.

Films — Animation

• Steven Universe: The Movie: In the series, the Gems' Empire is mentioned as having colonies in multiple galaxies. However, The Movie uses "galaxy" and "universe" pretty interchangeably. For instance, the prologue states that the Diamonds "conquered many worlds across the galaxy", but a signal to all their colonies is referred to as a "message to the universe".

Films — Live-Action

• Star Trek:
  • In general, most of the important activity in the universe appears to take place in the Milky Way Galaxy, even when dealing with the most ancient civilizations.
  • Star Trek V: The Final Frontier: The Great Barrier was planned to be located at the center of the universe but is changed to be placed at the Milky Way Galaxy's center instead. Beyond the Great Barrier is Sha Ka Ree, where creation is said to have begun as if the center of the Milky Way Galaxy were the center of the universe.

Franchises

• Halo:
  • Halo 4: Enforced. In the marketing campaign, the Big Bad Ur-Didact is announced as a threat to the universe when, in fact, he's "only" a galactic menace.
    Set in the aftermath of Halo 3, Master Chief returns to confront his own destiny and face an ancient evil that threatens the fate of the entire universe [...]
  • Halo: Silentium: The Precursors claim to be hundreds of billions of years old, far older than the universe. Why they remained in the same galaxy to be wiped by the Forerunner is anyone's guess.
• Star Wars Legends:
  • This continuity states that, while there are other galaxies, there's a hyperspace disturbance at the edge of the main galaxy preventing travel in and out and there's only one known place where the barrier doesn't work. So, pragmatically, their galaxy is the universe.
  • Outbound Flight: Jedi Master Jorus C'Baoth commissions an extra-galactic expedition, the Outbound Flight Project, in the last years of the Galactic Republic to seek out new life and civilizations beyond the galactic disk. Unfortunately, it ends disastrously thanks to Chancellor Palpatine who sees it as a nice way to get rid of some Jedi ahead of schedule.
  • New Jedi Order: The Yuuzhan Vong are from another galaxy, which earned them the nickname of Far Outsiders. They act akin to how humankind sees aliens — an invading species undetectable by common means (in this case, the Force), with an added flavor of Scary Dogmatic Aliens and organically-built technology.
• Warhammer 40,000:
  • The Eldritch Abomination Gods of the Warp live in the "immaterium", a sort of Spiritual counterpart to the Milky Way, and want to merge the two. Whether this extends to the rest of the Universe is up for debate. One argument in favor of this trope is that the said chaos Gods are the embodiments of rage, lust, hope, and love felt by the sentient species. Since they hail only from sentients in the Milky Way, it's as if there's not much out there.
  • The Tyranids are extragalactic insectoids that differentiate themselves from the main galaxy's sapient species in that they are the ultimate predators and are all variations of the same genetic theme. Essentially, an Alien Invasion of galactic scale.
  • For humans, FTL Travel is only possible in the range of the psychic beacon of the Astronomican, which is on Earth and doesn't even cover the totality of the galaxy (and, as of the 8th edition, has been cut off from about half of its former range). So for all intents and purposes, there is no universe outside the Milky Way.
  • Warhammer 40,000: Inquisitor — Martyr: Carvings decrypted from their ruins about "the grand pilgrimage" and "the world of strange stars" leads a tech-priest to a far-fetched theory that the Fabricatus race is not extinct, but instead left for another galaxy for an unknown reason. Said tech-priest also speculates if the Fabricatus were considering the possibility of an impending apocalypse.
  • Forges of Mars: The Necrons and the C'Tan specifically pick our galaxy to conquer and convert its background energy and primordial materials into more galaxies. This would have prevented the universe's heat death because by generating galaxies in between the already existing ones, they'd be making "stepping stones" that would reduce the travel distance. So, in a sense, the Necrons and the C'Tan intend to defy this trope by, at the same time, invoking it.

Literature

• Animorphs: Ellimist and Crayak are embedded into the fabric of spacetime and know that they could destroy the universe. But they only play their Great Game in the Milky Way. Ellimist alludes that there exist beings like himself and Crayak in other galaxies — Crayak himself originally fled to this galaxy to escape one!
• Isaac Asimov's Foundation series:
  • Second Foundation: Enforced. The stories originally handle the difference between the Milky Way galaxy and the universe (including multiple galaxies) correctly, but Taglines and back cover blurbs from Panther and Avon conflate the two as if they were synonymous.
  • Foundation and Earth: Despite the Milky Way being the only galaxy in terms of plot throughout the whole Foundation saga, it's discussed that humankind has the narcissistic tendency to believe its home galaxy is the only important bit of the universe.
    Golan Trevize: Yet we speak so much and so often of the Galaxy that it is all but impossible for us to see that this is not enough. The Galaxy is not the universe. There are other galaxies.
• In The Hitchhiker's Guide to the Galaxy, the Milky Way is the only galaxy ever specifically mentioned, even though the outlandish technology we see would presumably make intergalactic travel feasible — the Improbability Drive technology, in particular. The most notable references to "the Universe" are either metaphysical ("the Answer to Life, the Universe, and Everything") or temporal (the titular "Restaurant at the End of the Universe" is permanently located at the end of time itself). There is at least one mention of a wider physical universe when someone speculates that the enigmatic Galactic President may in fact rule all of it.

Live-Action TV

• Doctor Who: The Time Lords oversee the universe in a Custodianship fashion, yet all of their interventions involve the Earth and the Milky Way in some way or another. The titular character is particularly faulty of this thanks to his fascination with human beings.

Tabletop Games

• Isaac Asimov's Robots: The cover of the game conflates the fate of Earth (which you can save by correctly solving the mystery) with the fate of the galaxy (which the cover claims it's at stake).

Video Games

• Super Mario Galaxy: Exaggerated. Rosalina claims that Earth's sun is the center of the whole universe. So, it's less "what other galaxies?" and more "what other planetary systems?". This is coupled with Everything in Space Is a Galaxy given that the individual levels are called galaxies yet, in truth, are no more than weirdly-shaped planetoids. Oh, and groups of five galaxies comprise a dome. In turn, the Galaxy mentioned in the title is the complete collection of domes. Yeah, confusing but fun.
• Mass Effect: The Reapers are sentient cyborg spaceships that reside just outside the rim of our galaxy and return every 50,000 years to forcefully convert sentient species into more Reapers. Sentient species that have achieved space travel, that is, so they can purge them and try to prevent them from entering the galactic, Vicious Cycle of evolution peak/extinction. Guess only the Milky Way hosts such species since the Reapers spent those 50 000 years dormant, not, you know, traveling to other galaxies. At the end of Mass Effect 3, it's revealed this trope is justified given that the Reapers' creator intended for them to solely focus on the Milky Way.
• No Man's Sky: Double Subverted. The main storyline guides the player across the vast Euclid galaxy until the Galaxy Centre is reached, which allows intergalactic traveling. Nevertheless, it's discovered that the universe is in need of resetting and that means replacing the Euclid with another kind of galaxy. Therefore, the countless other galaxies are just parallel iterations of the original Euclid. After all, they are all simulations generated by the same AI, the Atlas.

Western Animation

• Winx Club: The Great Dragon is stated to have created the whole universe, spicing it up with life and magic. Now, the universe is called Magic Dimension (or Magic Universe or Kingdom, depending on the dub), but the said dimension is composed of a number of planets, realms, embedded sub-dimensions, and unnamed stars that all rotate around the planet Magix. So, the Magic Dimension as a whole is more of a galaxy than an actual universe. The only times where space maps have been shown have been in seasons 3 and 8 and the first website — all three instances show the Magic Dimension arranged like a big, physics-defying planetary system (not helped by the fact it's hard to pin down the exact difference between a planet, a dimension, and a realm). Funnily enough, the Earth's situation is very ambiguous, to say the least. It's outside the Magic Dimension, but it's unclear whether that means the Milky Way and the Magic Dimension are fellow galaxies or fellow dimensions/universes. The fact the Earth used to harbor magical beings of unclear origin (are they conquerors or natives?) further muddies the waters since it implies that it could belong to the Magic Dimension.

Real Life

• This was the view held by scientists until The Roaring '20s, when it was clear that a lot of objects considered as "nebulae" were actually galaxies (more or less) like our Milky Way. What finally tipped the balance was the realization and subsequent debates that what we now know to be the Andromeda Galaxy had to be farther than the universe's estimated size at the time. For a while afterwards, galaxies were often referred to as "island universes" as a lexical holdover of this model.
• In the very distant future (2 trillion years from now, over 100 times the current age of the universe), if the Universe keeps increasing the acceleration of its expansion, even the gamma-rays emitted from galaxies beyond the local group, which will have merged into one super galaxy by then, will have a wavelength longer than the size of the observable universe, putting them beyond the cosmological horizon and making them undetectable in any way. At that point, an observer inside their own galaxy would look out and see... nothing at all. Any conclusion that they live in a larger universe with many galaxies will have to be done either by inference or from reference to truly ancient records, rather than observation. Some astronomers have theorized that in those very distant ages, cosmology could become a sort of religion, as pretty much the only way to know how the Universe was born and what's out there would be records that somehow survived to that epoch, which of course would depend on how much evidence these had, the trust people put in them, etc.

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