Why didn't they just blow up the Stargate?

I just finished watching Stargate SG-1 and Stargate Atlantis, and one question has been bugging me the entire 314 episodes (plus two movies):

If you really didn't want someone traveling through your stargate, why not just blow it up? Even with the phenomenal cosmic power of Ancient technology. What's all this business about burying the stargate?

Answer

A stargate is very, very durable. They have to be. They are containing the incalculable energies of an Einstein-Rosen bridge capable of distorting time and space between two distant locations. No ordinary material could withstand both the energy contained nor the stress of the space-time distortion needed to make the connections between two gates.

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  Stargates appear to have some resistance to the effects of time or entropy as the oldest gate in the Milky Way galaxy is reputed to be 50 million years old!

  
  


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  It has been shown several times that attempting to destroy a stargate is no easy task. Normal human nuclear weapons have no effect on the material comprising the gate itself.

  
  


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  Even enhanced weaponry may destroy the planet before affecting the stargate.

  
  


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  The stargate is so durable and contains so much energy within it, that when active, overloading the gate can actually render planets uninhabitable with the force of its destruction.

  
  
  


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  A buried Stargate has the exact same effect as a destroyed one, it cannot be used effectively closing off access to that planet.

  
  

But once the Iris system was created, a gate could be obstructed without having to bury it. A wormhole is prevented from forming if a significant obstruction is present inside the Stargate's ring.

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  Consequently, a simple way to seal a Stargate is to bury it, as was done to Earth's Giza Stargate.

  
  



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  Another way of controlling travel through a Stargate is by placing a barrier just above the event horizon, which will prevent incoming matter from being reintegrated (essentially annihilating it). The Iris at the SGC and the Gate shield at Atlantis function in this way.

  
  

The Stargate Wiki entry confirms this:

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  Stargates are very durable; the oldest in the Milky Way is probably the Antarctic Gate, 50 million years old yet still perfectly functioning; the power source may have been younger.

  
  
  


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  The Stargates themselves are extremely resistant to damage or destruction: in one case, a Stargate survived a direct hit from a meteor,

  
  


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  while another was still capable of creating a stable wormhole while on a planet near a newly formed black hole.

  
  


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  A Stargate has also been seen to continue functioning while entering a star, though it was protected by a portable forcefield for a portion of its journey.

  
  



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  In the SG-1 fourth season episode "Chain Reaction", the SGC sent a naquadah-enhanced nuclear bomb to a planet whose surface had trace amounts of naquadah in its topsoil; the explosion destroyed the entire planet, yet the gate still remained open and intact.

  
  


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  In the ninth season of Stargate SG-1 the United States develops a naquadah-enhanced "Gatebuster" nuclear bomb that is theoretically capable of destroying a Stargate (the "Mark IX"). However, when it was first used it failed to destroy the intended Stargate, as an Ori shield defending the gate was being powered by the weapon attacks attempting to destroy it.

  
  


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  However, a later attempt (in the episode "The Shroud") successfully destroyed an active Stargate in the Pegasus Galaxy (which is connected to the Ori Supergate) by placing a Mark IX warhead behind the gate, thus preventing the energy from being absorbed by the open wormhole.

  
  

It should be noted that one of the stargate's more useful features is also its biggest weakness. The ability of a stargate to absorb energy from almost any source has been used several times as a means to destroy an active stargate.

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  If enough energy builds up in the gates superconductor, it can cause the naquadah to go critical effectively turning an active gate into a naquadah bomb as seen in the season 6 premiere "Redemption" where Anubis fired a weapon through an active wormhole triggering the detonation of Earth's stargate, which would have rendered the planet uninhabitable had the stargate not been successfully removed to outer space.

  
  


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  Additionally several gates were accidentally destroyed in the Stargate Atlantis episode "First Contact" As an unintended side effect of the Attero Device build by the Ancient scientist Janus. While these stargates did not build up enough energy to threaten entire planets, the explosions caused severe local damage.