I've been re-watching some episodes of SG-1 lately, and something struck me that I hadn't really noticed before: the destination gate spins before establishing a connection.

That got me wondering if the spinning just indicates that something's happening, like the throbbers on interactive websites, or whether there's actual meaning to it.

Is there any canon, in any of the shows/movies or the spin-off books, to indicate that this spinning is anything other than a progress indicator?

EDIT: To clarify, I'm not interested in the mechanics of dialling out; I'm curious about the process by which ates establish an incoming wormhole.

  • 2
    i think this is simply an error, because the destination gate shouldn't know its the destination gate till the dialing is completed, no? and once the dialing is completed the wormhole is instantly established, so unless the destination gate starts spinning AFTER the wormhole already has been made from the sending gate, i feel like this was just an error in plot design.
    – Himarm
    Commented Nov 7, 2014 at 14:56
  • 3
    @Himarm That's probably the most likely answer, but it's not necessarily correct. Especially early in the franchise (The Movie and "The Fifth Race", for example) there's evidence that the wormhole is not established instantaneously. That would make some sense; the destination gate presumably needs to do something to establish the wormhole on its end Commented Nov 7, 2014 at 18:11
  • Maybe a whole bunch of gates start spinning in sync whenever you start dialing one, and drop out as their addresses diverge from the one you're dialing...
    – Micah
    Commented Nov 8, 2014 at 4:29
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    @Micah: That would make it extremely difficult for cultures like the Rand Protectorate to not understand what exactly the 'Gate was for as long as they did. Ditto with Earth. It would be very unlikely that no one ever dialled part of their address until the first time it ever established a lock. Not to mention that SGC always knows an incoming wormhole is being established from the spinning, rather than only when the seventh chevron locks. Commented Nov 8, 2014 at 10:15
  • "It has to spin. It's round." :P see also: WARNING WARNING WARNING TVTROPES LINK tvtropes.org/pmwiki/pmwiki.php/Main/… WARNING WARNING WARNING TVTROPES LINK
    – BMWurm
    Commented Dec 6, 2014 at 16:10

4 Answers 4


Travel through the Stargate is not instantaneous - this is established in at least SG-1 episodes 1.01 Children of the Gods (it takes several seconds for the tissue box to arrive) and 5.05 Red Sky (shutting down the origin gate while goods are still in transit).

So I would say that when the origin Stargate has finished dialling and the event horizon opens, the event horizon at the destination does not necessarily open instantly. Rather, the destination Stargate starts spinning having just been dialled, and the event horizon opens several seconds later.

There is nothing inconsistent about the event horizon opening a bit later, if people and objects travelling through the gate also take some time to get there. Let's use this example where I open the origin gate at 12 noon exactly, to another gate that takes 20 seconds transit time. And we'll assume it takes about 10 seconds to dial.

  • 12:00:00pm Start dialling origin gate
  • 12:00:10pm Origin gate finishes dialling, and opens event horizon
  • 12:00:10pm Destination gate starts spinning (happens right away)
  • 12:00:13pm Traveller steps through the origin gate
  • 12:00:30pm Destination gate event horizon established (time gate opened +20s transit time)
  • 12:00:33pm Traveller steps out of destination gate (time stepped in +20s transit time)

I have not seen anything in Stargate that would be inconsistent with this explanation - but I'm happy to be corrected!

  • I agree with you completely, but I was really asking why the destination gate needs to start spinning. I can think of a few possible reasons (Some equivalent to a handshaking protocol, an indicator to people on the other end, etc.), but I was hoping for some tidbit of canon that I'd overlooked Commented Dec 6, 2014 at 17:33
  • I don't remember ever seeing a reason in canon why the incoming gate needs to spin. I think it's just for style (from an out of universe perspective).
    – Mark P
    Commented Dec 7, 2014 at 11:22
  • You're probably right about that, but considering Carter seems to have a pseudo-scientific explanation for pretty much everything else about the Gate, I figured it didn't hurt to ask if there may had been an off-hand mention in the show or the spin-off materials Commented Dec 8, 2014 at 23:47
  • I'm just watching an episode where Carter dials out after the gate starts to light up from an incoming connection. Since we see people start to enter the gate as soon as the event horizon has formed, the destination can't start to light up while they are already in transit. (or they would arrive at an occupied gate)
    – ths
    Commented Dec 15, 2014 at 19:16
  • If the destination gate is busy, the origin gate doesn't open at all. This is established in several episodes, such as in 2.17 "Serpent's Song". If the destination gate is available, then the origin gate opens, the destination gate starts spinning, and then it opens too. In which episode does Carter dial after the destination gate is lighting up? Surely the destination gate can't anticipate an incoming wormhole until it has been dialled?
    – Mark P
    Commented Dec 16, 2014 at 4:58

As the destination gate does not use its own power source for the inbound connection, it's possible that the spinning of the destination gate serves a diagnostic purpose. If the gate is spinning, and isn't currently being dialed it means that the inbound connection has begun, and the power is flowing from the dialing gate to the destination gate.

There are also user-friendly and safety reasons to have the spinning occur, as the gate has limited abilities to output information. If a connection is coming in, the gate designers would want the indicator for that to provide a meaningful and useful warning. By spinning, it blocks the ability for nearby people to dial out. So spinning both shows information and blocks attempts to dial out.


There are a couple trends. Some races are able to dial quicker- it takes the Goa'uld less time than the Tauri to dial, and the Nox were able to dial instantly. Also, how much the gate spins is reduced in the newer gates. The original gates, as shown in Universe, spin the whole gate. The next ones, the Milky Way ones, spin just a part of the gate. The newest ones are entirely non-moving, in Pegasus.

It makes sense that with the older ones the possibility of manual dialing meant that the co-ordinates are locked by the physical locking of the symbols- although they axed that feature later, it does indicate that it does have some functionality in the earlier versions. The Ancients would have realised that a lot of gates would have been on worlds where there may be limited resources, with a possibility of damaged DHD's. It seems the way it's designed is specifically geared towards that possibility.

So yes, the spinning is how dialling is achieved- although it may seem superfluous when dialling automatically, it's the way they chose to allow a manual dialling.

  • 6
    The QA is asking about the destination gate, not the origin gate. Your answer is absolutely correct as regards the point of origin. It does not, however, explain why the gate at the destination spins. That, to my knowledge, has never actually been explained. It doesn't actually make sense, since the destination gate serves no purpose other than to receive an incoming wormhole. When someone dials your phone, the numbers on your end don't beep before the ringing starts. Commented Nov 7, 2014 at 13:31
  • The answer would imply that there's no special meaning to the destination gate spinning, but I was hoping for more concrete evidence. I'll update the question to make it more clear what I'm looking for Commented Nov 7, 2014 at 18:12
  • Yeah, sorry, I completely misunderstood. I thought you wanted to know whether the mechanical actions of the outgoing gate were part of the mechanism of dialling or just an indicator. Afraid it does look like the incoming dial sequence is just to serve the story- to show characters a dialling is happening, for instance. Commented Nov 9, 2014 at 17:40

This is speculation but I can think of a few reasons why it would do this:

  1. safety for 1: that vortex is more than lethal (in fact it can rips apart ori motherships, I dont know anything thats survived the kahoosh)
  2. planets move in orbit, the destination gate might have to adjust its coordinate system to accept the incoming gate
  3. the receiving gate shows this like a caller id: just because humans cant stop an incoming wormhole the ancients probably could: think hey i'll jam that ring with a spanner to stop this caller
  4. The target gate may simply need to be in the same state and position to receive the incoming signal (worm holes have 2 ends, why should they not have to sync to connect)
  5. It looks good
  6. Were talking about creating wormholes here: we havent even found one yet, so the ancients are JUST a pretty smart bunch

I know theres no evidence to support this but I think in universe you wont get one, these are just the most likely reasons from my point of view

One final thing Pegasus gates do this too (just without the spinning), it seems likey num2 or num4 is the best in universe reason

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