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?

2 Answers 2


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
    Commented Jan 30, 2014 at 2:31
  • 1
    @TheDoctor Added a bit about the difference between the event horizon, the wormhole, and the vortex.
    – BESW
    Commented Jan 30, 2014 at 2:36
  • 2
    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
    Commented Jan 30, 2014 at 3:18
  • 1
    @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
    Commented Jan 30, 2014 at 22:34
  • 2
    @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. Commented Jun 26, 2016 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.

JACK: So this iris is going to hold right?

  • Initially titanium but later trinium.
    – Anthony X
    Commented Oct 23, 2022 at 20:44

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.