Why Doesn't Star Trek Ever Leave The Milky Way Galaxy?
by Witney Seibold · /FilmWe may receive a commission on purchases made from links.
Welcome to Trekspertise, a series where we break down the technology, history, details, and decisions that make the Star Trek universe so complex — and so fun.
Space is big. How big? So big, it would take the fastest starship in fiction to not even begin to traverse it. The writers of "Star Trek" know that the distance between planets is massive, so they established limits; even at warp-11, it would take the Enterprise about 75 years to traverse the diameter of the galaxy in "The Original Series."
In the lore of "Star Trek," the disc-shaped Milky Way has been divided into four quadrants. Earth is located in the Alpha Quadrant, rather close to the border of the Beta Quadrant. Most of the alien species we know on "Star Trek" are native to the Alpha Quadrant, although Klingons and Romulans are from the Beta, so Starfleet vessels aren't seen over in that quadrant too much. "Star Trek: Deep Space Nine" featured a stable wormhole that reached into the Gamma Quadrant, while "Star Trek: Voyager" was about what happened when a Starfleet vessel, the USS Voyager, became stranded in the Delta Quadrant, over 70 years from home.
But all of these stories are still firmly within the borders of the Milky Way galaxy. Apart from a few one-off stories involving high-powered engines or godlike magic, "Star Trek" has never traveled far enough to reach another galaxy. This seems like a great, missed storytelling opportunity. What would life look like in Andromeda? Would people even be humanoid? Why not go there?
There are a few contrivances that have kept "Star Trek" from traveling so far afield. Notably, there are the realities of interstellar distances, and the limitations of Trek's warp engines. But more than that, keeping the action set in one galaxy makes for narrative tidiness.
The galactic barrier, and the rare times Star Trek did leave the Milky Way
One of the reasons "Star Trek" didn't leave the galaxy was a fantasy contrivance introduced in the original series episode "Where No Man Has Gone Before" from 1966. In that episode, it was established that the Milky Way is surrounded at its edge by a large, palpable energy field called the galactic barrier. Communications can't pass through it, and if a ship tries to traverse the barrier, it causes damage to the ship's engines. (The barrier also imbued some crew members with godlike powers, although that was only ever a one-time problem in the franchise.)
The barrier was enough to destroy ships sometimes, as it did in the 1968 episode "By Any Other Name," wherein a few Kelvan starships were destroyed when entering the Milky Way from outside. The Kelvans, one of the most powerful species in "Star Trek," hijacked the Enterprise, retrofitted it, and were able to fly out of the Milky Way without much hassle. The galactic barrier also provided some plot points in later episodes of "Star Trek: Discovery."
To be clear, there is no such thing as a galactic barrier in real life.
Very occasionally, "Star Trek" would zip away from the Milky Way and briefly end up in another galaxy. In the 1987 "Star Trek: The Next Generation" episode "Where No One Has Gone Before," the Enterprise-D conducted a few engine experiments that forced it to travel at untold speeds. After one test, the ship ended up in Galaxy M33, 2.878 million lightyears from Earth. After another burst of speed, it ends up in a place the crew can't even determine. The drama of the episode, however, is about returning to the Milky Way, not exploring where they are. M33 is too far to trek, even by "Star Trek" standards.
What are the closest galaxies to Earth?
So one of the main reasons "Star Trek" stays in the Milky Way is because of this imaginary galactic barrier. In real life, the Milky Way reaches out into space, and that's that. The galactic barrier is a magical, writerly contrivance that keeps vessels safely inside the Milky Way. In short, it's too dangerous to leave. In "By Any Other Name," the barrier was stated to only exist around the edge of the Milky Way, although some ancillary "Star Trek" literature (notably "Star Trek Star Charts") states that it surrounds the top and bottom of the galaxy as well.
Speaking of Galaxy M33, it's in the constellation Triangulum, and it, like the Milky Way, is a spiral galaxy. It's 2.878 million lightyears from us, and according to the website AstronomyTips.com, the Triangulum Galaxy is the fifth closest galaxy to Earth. The closest galaxy to us is the Canis Major Dwarf Galaxy, only discovered in 2003. That's only 25,000 lightyears away from Earth. For comparison, Earth is about 26,000 lightyears from the supermassive black hole Sagittarius-A, which is located at the center of our Milky Way.
With a galaxy so close to us (relatively speaking), one might think that getting there in "Star Trek" would be a piece of cake. After all, the Enterprise-A flew to the center of the galaxy in both "Star Trek: The Animated Series" and in "Star Trek V: The Final Frontier." Trekkies, however, like to ignore those chapters in the saga, as they contradict one another. Also, it's pretty widely accepted that "Star Trek V" sucks more than a black hole. But, no, Canis Major Dwarf Galaxy remains unvisited by Starfleet.
The intergalactic medium is too large to trek through
The second closest galaxy to Earth is the Sagittarius Dwarf Elliptical Galaxy, discovered in 1994, which is about 70,000 lightyears from us. Third are both the Large and Small Magellanic Clouds, which are approximately 163,000 and 200,000 lightyears from us, respectively.
Fourth closest to Earth, and perhaps best-known, is the Andromeda galaxy, which is about 2.5 million lightyears away. The Milky Way contains dark matter, so it is technically the larger of the two galaxies, but Andromeda is nearly as large. It's predicted that in about 4 billion years, Andromeda and the Milky Way will collide, causing them to merge into a single mash-up galaxy of epic proportions. Bad news, though: "Grand Theft Auto VI" will still not have been released.
Given what we know about warp engines in "Star Trek," let's do some calculations. Luckily, resourceful Trekkies have constructed online warp speed calculators, so if we're going by the warp gauge on "Star Trek: The Next Generation," it would take a starship traveling at warp-9 approximately 1,648,663 years and three months to reach Andromeda. Heck, at warp-9, it would still take a vessel 16 and a half years just to reach the much-closer Canis Major Dwarf Galaxy.
The space between galaxies is called the warm-hot intergalactic medium, or WHIM, and it doesn't contain a lot of stars. It contains ... well, gas. The theories as to what's out there are based on computer models and the behavior of various particles, but as stated in a handy rundown in Wired, "The WHIM is so hot that it ionizes hydrogen, stripping its single electron away. The result is a plasma of free protons and electrons that don't absorb any light."
Whatever's out there, though, it sure ain't stars, and it sure won't contain the kinds of places where Starfleet vessels are used to stopping. "The Next Generation" crew would need to spend over a decade trekking through a big span of gassy nothingness to get to the friendly aliens on the other side.
Really, this is all about dramatic tidiness
So, the limitations of warp engines make intergalactic travel non-viable, even in "Star Trek."
Really, though, the main reason "Star Trek" stays inside the Milky Way is narrative clarity. After all, it's an entertainment franchise being made on Earth, on a budget, by some very human writers. It keeps the narrative so much easier to follow if we stick within a single 100,000-lightyear-wide disc, divided into handy-dandy quadrants.
In the "Star Trek: The Next Generation" episode "The Chase," it was explained that a mysterious, impossibly ancient species called the Progenitors once seeded the bulk of the Milky Way with their DNA, causing all alien species to evolve to look kind of like them (that is: one head, two arms, etc). This was a handy plot contrivance, as the makers of "Star Trek" hired all-human actors (as far as we know) to play aliens. Traveling to another galaxy would force humans into a place where the Progenitors didn't reach. That would, in turn, force the show's writers to invent non-humanoid life forms ... and those require expensive special effects to visualize. Staying in the Milky Way provides a handy way to cut production costs.
And while modern VFX could perhaps visualize an endless string of non-humanoid creatures, it wouldn't take too long before a human audience started to disconnect from the series. "Star Trek" has an easier time of exploring human philosophy and ethics if we can see humanoids doing it.
So we stay in the Milky Way. It's a star trek, not a "big empty space of nothingness" trek. And it's also a TV series that needs to be filmed in a dramatically satisfying way. Besides, the Milky Way is plenty large unto itself, and there's plenty left to explore right here. We don't need to zip off to the Canis Major Dwarf Galaxy to find something interesting.