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Ripple Effect

09.13 Episode 187
Airdate: January 20, 2006

An irregular energy spike accompanies an unscheduled off-world activation, and SG-1 steps through the gate at the SGC. During their briefing, SG-1's report contains peculiar discrepancies, but before they can be explained, the gate activates again, and another SG-1 team arrives. Carter suggests that the explanation lies in the multiverse theory of quantum physics. The first team is probably a duplicate that arrived from a parallel universe when a black hole ruptured subspace and created a bridge between universes. However, as they seek a way to return the duplicate team to their own world, the gate activates again and a third SG-1 team appears.

Carter theorizes that a subspace tear has caused a ripple effect across several realities, making our universe a convergence point, and soon over a dozen SG-1 teams have arrived on the base. One team includes Dr. Fraiser and Martouf, whose bittersweet reunion with SG-1 is accompanied by a plea for help in curing the Ori plague on their world. However, Carter's proposal to seal the rupture between universes would prevent any of the teams from returning home. Nevertheless, Landry approves the mission. With the help of the Asgard Kvasir, the first two SG-1 teams depart on Prometheus to deliver a warhead into the singularity.

At their destination, the alternate SG-1 team hijacks the Prometheus and locks SG-1 in the brig. It had been their mission from the beginning to enter an alternate universe, commandeer a ship to Atlantis, and steal a ZPM with which to fight the Ori. What's more, they have a way to return home. Instead, however, SG-1 regains control of the ship and scraps the mission. Now with a means to invert the subspace rupture, the team returns to the SGC where a directed energy weapon through the gate reverses the convergence effect. As each team is sent home, Landry provides Fraiser and Martouf with the cure to the plague that will save their world.

Story by: Brad Wright and Joseph Mallozzi & Paul Mullie
Teleplay by: Joseph Mallozzi and Paul Mullie
Directed by: Peter DeLuise

Guest Starring: Teryl Rothery as Dr. Fraiser, JR Bourne as Martouf, Gary Jones as Sergeant Harriman, Bill Dow as Dr. Lee, Lexa Doig as Dr. Lam, Dan Shea as Sergeant Siler, Trevor Devall as Voice of Kvasir

Reference: Alternate Reality, Alternate Reality - Ripple Effect, Asgard, Asgard Energy Weapon, Asgard Transport Beam, BC-303, Black Hole, Samantha Carter, Entropic Cascade Failure, Janet Fraiser, Kvasir, Carolyn Lam, Bill Lee, Martouf, Multiverse Theory, Prometheus, Sergeant Siler, Stargate, Time Dilation Device


Destinations & Inhabitants


Destinations & Inhabitants



  • The multiverse theory of quantum physics posits the existence of parallel universes, an infinite number of ever-growing, alternate realities that exist concurrently with our own. The theory holds that anything that can happen will happen, if not in this reality, then in another. We're part of a meta-verse in which individual sub-universes are continually being generated.
  • The alternate team had opened a wormhole through a black hole, then used an energy weapon to blast a bridge into this universe. Carter proposes that the first spatial tear may have caused a ripple effect across several realities transforming an area of their subspace into a kind of funnel that's redirecting their gate travel to this universe so that our SGC became a convergence point.
  • To reverse the process, SG-1 established a wormhole to PX7-455, fired a directed energy weapon on loan from the Asgard through the gate to reverse the space-time rupture effectively inverting the convergence effect, and allowing dialing to create wormholes that would follow the inter-universal pathways already created by the initial trips here.
  • At least 18 SG-1 teams arrived. Over 50 SG teams were turned back.
  • The 12th alternate SG-1 team to arrive included Martouf and Janet Fraiser as members. Martouf joined the SGC to be closer to Carter, they lived together for quite some time, but Carter is with someone else now. Fraiser joined SG-1 because Carter is on her honeymoon. Their Earth is being ravaged by the Prior plague, for which Fraiser brings back the cure.
  • The journey between gates takes on average 0.3 seconds travel time. Travel time for the alternate SG-1 team was 3.4 seconds.
  • Kvasir arrives to assist SG-1. Thor and Heimdall are in a neighboring galaxy dealing with a most sensitive matter.
  • Currently the Atlantis ZPM is powering one-way transportation back to Earth and cloaking the city of Atlantis.
  • Alternate Mitchell's departing words to Mitchell: "When the time comes, cut the green one."


  • So you're saying that somewhere in an alternate universe, I got to second base with Amy Vandenberg? [Mitchell]
  • I'm willing to make the occasional exception, but I am not about to turn this base into the Grand Central Station of the multiverse. [Landry]
  • You know, I read all the mission reports on the Asgard. They're not what I expected. [Mitchell]
    What were you expecting? [Carter]
    Well, pants, for one. [Mitchell]
  • You don't have beards, so you're not from the evil twin universe, right? [Mitchell]
  • Hey, Mitchell... When the time comes, cut the green one. [Alternate Mitchell]


  • Injuries:
    • Mitchell: knocked out by alternate Teal'c