In the Voyager episode "Relativity", the events are centered partially around the timeship of that name. But if you are exploring (or monitoring) time rather than space, what is the reason for doing so from a ship off in space somewhere rather than a surface base on a planet or appropriate moon (or possibly even an orbiting space station), which would surely have easier access to most resources and avoid many of the problems which, even in the Star Trek universe, exist in space travel?

2 Answers 2


You would create a "timeship" for the same reasons you create a spaceship, to go places and in this case into times, that have localized temporal anomalies that need investigating. The Wells-class timeship, Relativity, still has all of the responsibilities of a ship of the Federation of the 29th century, with the additional duties of investigating temporal anomalies which they appear to be able to be detected before their effects can be felt in the timestream.

In the Voyager episode "Relativity", the placement of a bomb hidden in the timestream makes it necessary for an agent to be able to be placed both in space and in time. The image below shows a display from on board the Relativity as the crew attempts to rescue Seven of Nine from a point in the timestream.

Screenshot from Relativity, Season 5, Episode 23

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    While this may well be a partial answer, when Lt. Ducane specifies the transport target, it is specified as both temporal and spatial coordinates. When the bomb is placed on Voyager (and to which time frame Seven of Nine is sent), Voyager is in the Delta quadrant, while Relativity presumably is not (I don't think there's any reference to Relativity's position in the episode). Why, then, can't they just as easily do temporal and spatial scans and transports from a celestial body surface?
    – user
    Jun 30, 2012 at 22:30
  • Note that I am not saying there aren't times when a starship capable of some form of time travel (as shown in e.g. Year Of Hell) can be useful. But surely there would be times, such as seemingly the events depicted in the episode Relativity, where such capability would not be needed.
    – user
    Jun 30, 2012 at 22:32
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    Planets have huge gravitational fields which may inhibit their ability to peer and work through time. Since time travel and temporal distortions can be problematic, it might be best to have such equipment far away from planetary surfaces. Jun 30, 2012 at 22:34
  • I suppose that works as a possible explanation - even with artificial gravity aboard the ship, it might be easier to compensate for it on a ship suspended in a zero or near-zero (see temporal distortion origin in Year of Hell as Voyager is dropped in the vicinity of 20th century Earth) gravity environment, and artificial gravity doesn't need to be the same as that of a whole planet particularly if you have other priorities to take into account. Gravity wells can be nasty things.
    – user
    Jun 30, 2012 at 23:01
  • @MichaelKjörling: That wasn't Year of Hell Aug 11, 2014 at 18:47

I would suggest that a ship is vital if you wish to travel in time.

There's one thing that everybody conveniently leaves out of time-travel films: things move.

Back to the Future is especially guilty of this.

Stand in one spot. Now travel five minutes into the past. Now, as you asphyxiate in the vacuum of space, look around. See that? That's the Earth, and it's coming your way.

Time travelling must necessarily involve movement relative to something. If you want to travel in time to Earth in the 1400's (for example), you don't just need to jump through time - you also need to jump several billion kilometres through space to where the Earth was at that time.

So a ship is the ideal vessel for that.

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    Depending on where the spot is, you may well end up inside the earth? It takes 7 minutes for it to travel a distance in space equal to its diameter.. Edit: but wait a sec.. I forgot that the universe is also expanding.. That complicates things if your time machine holds you at a fixed point relative to the epicentre of the big bang
    – Caius Jard
    Oct 12, 2016 at 6:47
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    Not everybody ignores it. (That's not to say that Star Trek's time travel is necessarily plausible in general.) How can I explain that a time travelling apparatus moves itself through time but appears in the same location? on Worldbuilding discusses some mechanisms for how time travel could end you up in the same geographical location but at a different time, and The Girl From Tomorrow (part one, part two) uses such a restriction as a plot point.
    – user
    Oct 12, 2016 at 7:23
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    Gregory Benford's novel "Timescape" deals with exactly this concept of temporal displacement of the physical target. Facing an ecological disaster in the future, scientists use tachyons and precise data on the location of 'where and when' Earth was back in the 1960s. They send a warning back to the only scientist of the era who was working with the right sort of equipment to pick up the message. It's a great read if you're into that sort of thing.
    – flith
    Oct 12, 2016 at 11:21
  • @CaiusJard there is no epicentre; the Big Bang happened everywhere
    – OrangeDog
    Apr 10, 2021 at 16:12
  • In the theory of relativity there is no objective truth about whether an object is at the "same point in space" that it was at some point in the past, or whether it has "moved", this depends on your choice of reference frame. So if you're using a science fiction idea of instantaneous jumps through time (as opposed to continuous travel as in H.G. Wells or travel through a wormhole), you have invent some rules for how to "aim" the jump in space as well as time, but there shouldn't be any default point in space you would "naturally" appear, unless you want to throw out relativity.
    – Hypnosifl
    Apr 10, 2021 at 16:38

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