I may just not remember this, but doesn't the Stargate horizon destroy everything in its way when the gate is activated? How then, can the Stargate's Iris stay in tact?


The iris is so close to the event horizon that it disrupts the vortex.

It's a handwave, sure, but the official explanation is that "if the event horizon is blocked to within a few microns, the vortex will be suppressed." (source)

This works because they make a distinction between the vortex and the event horizon. The event horizon is the near end of the wormhole; the vortex is the momentary eruption of destructive energy which heralds the creation of the wormhole. When a solid object is extremely close to the event horizon when the wormhole forms, the associated energy burst is suppressed.

Once the wormhole is established, the iris has the same effect on any matter coming through; it disrupts whatever comes out of the event horizon, preventing matter from forming just the same way it suppressed the vortex.

  • hmm..but they are able to make the wormhole.. Good to know, I didn't remember them saying that. I do remember them saying it would keep matter from reintegrating. – The Doctor Jan 30 '14 at 2:31
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    @TheDoctor Added a bit about the difference between the event horizon, the wormhole, and the vortex. – BESW Jan 30 '14 at 2:36
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    AFAIK, the kawoosh is generally understood to be excess energy actually coming out of the event horizon, same as any object passing through. The Nox were able to suppress the kawoosh entirely. – Izkata Jan 30 '14 at 3:18
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    @TheDoctor - there's an episode (can't remember which one) where they (possibly only talk about) set the iris back a little bit and it completely blocks the wormhole from forming – HorusKol Jan 30 '14 at 22:34
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    @AnthonyX - That actually follows all the rules and they explained it in the show. The gate was covered while still active, and so when it shut off, it effectively worked as a constant iris, allowing dial-ins but no entry. They then used a trick a goauld used on their iris (subatomic particle bombardment) to eat away at the material on the other side until there was JUST enough space for a kawoosh to form. – starpilotsix Jun 26 '16 at 0:34

The destructive wave you see is not the event horizon, it is the "unstable vortex of forming a wormhole" aka "the Kawoosh".

CARTER: Well since you disintegrated the Alteran communication stones and the base terminal in the kawoosh—

MITCHELL: I'm sorry, the what?

CARTER: The unstable vortex of a forming wormhole. Kawoosh.

MITCHELL: Don't think I've ever heard you call it that before.

CARTER: Really?

MITCHELL: Don't get me wrong, it's good.

CARTER: No, I mean, I'm sure—

The Iris sits micrometers above the event horizon preventing matter or anything else (even the Kawoosh) from forming. Sam explains it in "The Enemy Within".

DANIEL: So this iris is going to hold right?

CARTER: Pure titanium. Less than three micrometers from the event horizon. It won't even allow matter to fully reintegrate.

DANIEL: So this iris is going to hold right?


It's been a while since I watched stargate but if I remember right the iris would close very quickly just after the wormhole formed... so the "whoosh" happens and then the iris gate closes to block any incoming matter.


IIRC the vortec actually comes out of the back of the gate when the iris is engaged

the way they explain it is that the iris is offset from where the event horizon forms by a few microns which allows the wormhole to form but any matter trying to reintegrate would be destroyed

the kawoosh not destroying the iris is most likely one of the gate programs safeguards (the program the gates themselves have not the SGCs program) the gate senses that something will be destroyed if the energy is bled out one way so it bleeds it the other

my premise could be wrong though im off to pay closer attention to offworld activation scenes

  • It's firmly established that vortex does not come out the back of the gate if the front is obstructed, and the lack of vortex-related safeguards even with a DHD has been important to the plot on multiple occasions. – BESW Jan 30 '14 at 12:37
  • @BESW, severa may be thinking of the funnel that appears in the back of the gate in the original movie. The funnel-in-the-back does not appear in any TV episode of the franchise nor any subsequent movie, to my knowledge. – Brian S Jan 30 '14 at 17:06
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    @BrianS It does appear in the black hole episode due to the extreme gravitational pull, but yeah, it's not there under normal circumstances – Izkata Jan 30 '14 at 17:50
  • I'll have to watch more episodes I might have been confusing my sound effects – severa Jan 30 '14 at 22:46

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