Has any episode, game or novel provided an in-universe answer?

This answer seems give an approximate size, but as the question states:

how much of Space is included in the Federation-explored region of the Star Trek Universe?

I'm referring the the universe as whole with and without the Federation.

  • Related but not a duplicate: How big is the known Star Trek universe?
    – Rand al'Thor
    Nov 28, 2019 at 16:03
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    Once, yes: youtube.com/watch?v=1pWWC_58YTs Nov 28, 2019 at 16:07
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    There is an unstated assumption here that the Star Trek universe is different somehow than our universe, which I don't think should stand unsupported.
    – DavidW
    Nov 28, 2019 at 16:08
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    See "Remember Me" for a size of the Trek universe (the figure may be a little off). Happy Thanksgiving! Nov 28, 2019 at 17:07
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    @BMFForMonica - Correct!
    – user123444
    Dec 1, 2019 at 18:29

2 Answers 2


As already pointed out in the comments:

There is an unstated assumption here that the Star Trek universe is different somehow than our universe

which AFAIK does not hold: there is no indication that the Star Trek universe at large is different from our own one.

Given that Gene Roddenberry in the introduction to his TNG writer/director's guide (aka The Bible) talks about "our galaxy" in realistic numbers, and that surrounding galaxies like Andromeda and Triangulum are common to both universes (Star Trek and our own), there is no reason to believe that the rest of the series universe is different. For what it may worth, Star Trek takes place neither in Middle Earth nor in The Matrix.

Arguably, the reason is that any such difference would be actually irrelevant for the series fictional world: for all its grandiose, Star Trek actually takes place in a relatively tiny vicinity around Earth, which does not even include the whole of our own Milky Way galaxy.

In TOS episode By Any Other Name, it is made explicit that even a trip to the nearby Andromeda galaxy is actually way off consideration, since it would take thousands of years for a Constellation-class starship of the era to make the trip, even if subsequent advances in technology would lower that time to only some hundreds of years at maximum warp.

Given this setting, it is only natural that any actual consideration of the whole universe's size or shape is actually absent from the show; even if we may be able to unearth some obscure slip-of-the-tongue relevant statement from some cosmic being like Q, admittedly one should not rush to take it at face value, in-universe or otherwise...

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    Highly related to your assumption: When did our universe and the Star Trek universe diverge?
    – Rand al'Thor
    Nov 28, 2019 at 17:35
  • @Randal'Thor thanks, but it would seem that the linked thread is actually about the history, and not the universe (or Universe?) in the literal meaning of the word, as asked here
    – desertnaut
    Nov 28, 2019 at 17:38
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    Right, but if the history of the universe is the same as ours up to a specified point in time, that strengthens the evidence for the assumption that the physics matches up with ours.
    – Rand al'Thor
    Nov 28, 2019 at 17:43
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    I think Where No One Has Gone Before firmly establishes that the Star Trek universe is significantly different from ours, both astronomically and in terms of physics. (That's if you weren't already convinced by the nebulae.) Nov 28, 2019 at 20:32
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    Star Trek has a lot of speculation about physics, and that's what the question is about. It's very possible that Star Trek canon contradicts what current scientists say about the size and shape of the universe.
    – Jetpack
    Nov 29, 2019 at 3:21

With relation to size we learn, in VOY: Threshold, that the universe is infinitely large since it requires infinite velocity to occupy every point in the universe.

KIM: Nothing in the universe can go warp ten. It's a theoretical impossibility. In principle, if you were ever to reach warp ten, you'd be travelling at infinite velocity.


JANEWAY: It would appear that the theory of infinite velocity is correct. It may be possible to occupy every point in the universe simultaneously.

As to the shape of the universe, it would appear that the physical universe (consisting of all matter) is expanding into a infinite void and is roughly spherical.

We see it from the outside (at the ripe old age of about 2 seconds) in VOY: Death Wish.

enter image description here

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    I don't see how the quote implies that the universe is infinite in extent; even a finite universe could require infinite velocity to be everywhere simultaneously. Beyond that, the quote doesn't even imply that that infinite velocity is even required; it could be a sufficient but not necessary condition. Nov 29, 2019 at 2:50
  • No. Just no. Not even the writers of "Threshold" consider it canon.
    – Jasper
    Nov 29, 2019 at 13:55
  • @Jasper - You are mistaken. They consider it terrible, but not non-canon.
    – Valorum
    Nov 29, 2019 at 17:20
  • @DanielR.Collins - The universe must be infinite in extent in order for infinite velocity to be a requirement. Otherwise a lower speed could be used. QED
    – Valorum
    Nov 29, 2019 at 17:22
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    @Valorum. That's not true. E.g.: Say the universe has 100 particles and your speed is 1000 particles/sec (or whatever units make sense); then you're "at" each particle at best every 0.1 sec, not simultaneously. Change those to whatever finite numbers you like and you still get a finite delta between particles. Only infinite velocity serves to bring the time delta ratio to zero. (Or alternatively a universe with zero particles.) Nov 29, 2019 at 22:22

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