I was just watching an old Star Trek Voyager episode and Harry Kim said roughly "Captain, another super nova exploded just 0.36 lightyears away!". My question here is how something can happen 0.36 lightyears away and still be considered just.

I can accept that they travel faster than light, by using subspace; something I imagine as a fourth dimension in space. So they still are slower than light in four dimensional space, but appear to to travel faster than light in three dimensional space.

So, is there any reasonable explanation for this statement or is it simply bogus in the script?

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    There's a point in science fiction where you need to have what's called a suspension of disbelief. Just accept that it works that way... even though it could never actually work that way, lol. Commented Aug 11, 2011 at 21:18
  • Also, you answered your own question in your question Commented Aug 11, 2011 at 21:20
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    This is only an issue if you believe the speed of light cannot be bypassed, an unfortunate belief held by the science of today. Science is constantly finding new ways to do things once believed to be impossible. The speed of light will be no different, some day.
    – BBlake
    Commented Aug 11, 2011 at 21:26
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    I vaguely recall a few conversations on the Enterprise in TNG where sensors and subspace were linked - can't remember anything specific though. I'd imagine that long range sensors can detect the subspace distortions of warp drives or whatever. Then again, Starfleet seems to have the ability to photograph people's faces from quite some distance (in Unification Part I where they get a picture of Spock on Romulus)
    – HorusKol
    Commented Aug 11, 2011 at 23:06
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    How would you make use of FTL travel across interstellar distances safely if you don't have sensors that can "see" FTL? You'd be constantly at risk of smashing into planets/stars/other ships because your navigational data is always hours/weeks/years/centuries old. Commented Apr 25, 2014 at 3:22

5 Answers 5


From Wikipedia:

In the Star Trek fictional universe, subspace is a feature of space-time which facilitates faster-than-light transit, in the form of interstellar travel or the transmission of information.

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    Which also applies to their sensor technology as well, allowing them to see things far away at the moment they happen, or close enough after that.
    – BBlake
    Commented Aug 11, 2011 at 21:24
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    sensor readings are transmissions of information ;P Commented Aug 11, 2011 at 21:27
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    I read "transmission of information" more as communications and data streams rather than sensors, but I see your point.
    – BBlake
    Commented Aug 11, 2011 at 21:30
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    I don't have exact references, but I do recall multiple references to "subspace sensors" and "subspace readings." The impression I always had, from TNG episodes, was that normal space activity (ship movement, weapon discharges, large energy releases) had a measurable impact in subspace that they could somehow observe from normal space.
    – Saiboogu
    Commented Aug 11, 2011 at 23:53

Subspace is an FTL energy transmission effect of the Star Trek universe.

Some subspace sensors are active; a subspace pulse is sent out, and an echo received back. Aside from the transceivers, it's the same basic method as radar, ladar, and active sonar.

Some subspace sensors are passive, receiving subspace signals from other sources. We know this because a subspace radio receiver is in fact also axiomatically a subspace passive sensor.

Things we know can be detected: Stars, planets, ships at warp, subspace communications.

According to Memory-Alpha.org, the Star Trek Wiki restricted to canon sources, in the subspace article, tetryons are a subspace particle, and Warp drives and Transporters are subspace technologies.

This implies subspace targeting of life forms as well.


Sending information takes less energy than moving a starship. So subspace radio waves and other scanning waves can be sent at much faster speeds than you could move the starship.

Think of it as the difference between a jet plane, travelling at a few hundred miles an hour, and a radio wave, travelling at the speed of light.

A subspace radio wave travels at warp 9.9997 or 23 lightyears an hour (TNG technical manual page 111)

At 0.4 lightyears a minute, a scanning pulse sent from the ship 2 minutes before, would have only just returned.

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    Well, except that warp speed is not just "going really fast". The thing is, that in contrast to the communication signal, the ship carries the device that generates the warp bubble around, so it can continue to bend space-time around it. The signal, however, once sent out carries no warp core along its trajectory. So your analogy with jet planes and radio waves doesn't really work.
    – bitmask
    Commented Apr 25, 2014 at 8:12
  • I shall clarify. The signal(radio wave) requires less energy than the ship(jet plane) to propagate through subspace.
    – anoxm
    Commented Apr 25, 2014 at 12:09

Well, Starfleet extensively uses subspace field manipulation in much of their baseline technology operation. Their technology is subspace based... so, it stands to reason that if they use subspace for FTL (namely Warp), then the likelihood will be that they managed to develop sensors that operate on same principles (though I'd imagine that it would be a lot easier and faster to scan something lightyears away than actually pushing a ship to a desired location using same principles).

It could be a combination of Quantum Entanglement technology with subspace. Or possibly using light as a wave to travel along certain subpsace bands... or they could be using a combination of those two and other methodologies.

Either way, a starship doesn't have to be in Warp to be able to use subspace technology or receive information that's using subspace.

As we saw, ships can easily lower their mass using subspace fields while at sublight (this is actually implied as standard practice by O'Brien in opening episode of DS9, and all SF ships tend to have their own subspace signatures and fields whether in or out of warp).

Kim's statement would basically be no more different if you were observing a supernova with a basic telescope. Only, Voyager's sensors (and technology in general) can see things happening lightyears away in real time (because they likely have a subspace sensor array which is capable of receiving information at FTL) and are accurate to the subatomic level.


Long ago I was at a convention where D.C. Fontana was being asked questions. A boy who looked about 12 asked her how can phaser beams which travel at the speed of light pass between starships at warp speed. I thought that was a very good question. And she asked him how do we know that phaser beams use light and thus travel at only the speed of light?

And I thought that was a very good answer and decided that some of the space battles in Star Trek: The Original series must show faster-than-light phaser beams.

Years later I saw a writer's guide or technical manual for Star Trek: The next Generation which stated that only photon torpedoes should be used in battles at warp speed since phasers have no military value at warp speed. This seemed to imply that Next Generation phasers only use electromagnetic radiation.

And I wondered if the Star Trek staff ever bothered to list all their answers to questions and send them to other Star trek staff members so they could pick the best answers and then all give them when asked. I am not very methodical but that seemed like a no-brainer to me.

My theory is that TOS starship phasers used subspace spectrum radiation which traveled much faster than light, but in the later era of TNG starship phasers used electromagnetic radiation which traveled at the speed of light, perhaps because photon torpedoes had become much better than even subspace frequency phasers for warp speed battles anyway.

In the era of TOS subspace radio traveled much faster than starships (but always at the speed of plot) and starship sensors could detect events either instantly or at a speed exceeding (old style) warp 15 as "The Changeling" showed.

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