In the end of Avengers (2012) movie,


SELVIG: Loki's scepter, the energy...the Tesseract can't fight. You can't protect against yourself.

BLACK WIDOW: It's not your fault. You didn't know what you were doing.

SELVIG: Well, actually I think I did. I built in a safety to cut the power source.


TONY: Well, that sounds exhausting. The rest of the raw materials, Agent Barton can get his hands on pretty easily. Only major component he still needs is a power source. A high energy density, something to kick start the cube.

Well, Selvig used Stark Tower's arc reactor as power source, but it was only necessary for booting the portal device as Tony predicted.

JARVIS: Sir, I took off the arc reactor. The device is already self-sustained.

Which power source did Dr. Selvig suggest to cut? Was he talking about cutting the cube's connection with rest of the portal device?

  • I believe he was talking about using the Mind-gem as a sort of key to lock the power back in the Tesseract.
    – Valorum
    Oct 13, 2017 at 19:41

1 Answer 1


This is answered directly in the next line:

I built in a safety to cut their power source.
Loki's scepter. It may be able to close the portal. And I'm looking right at it.

So he knows you can use the power in Loki's scepter to stop the cube's effects and close the portal. Since both objects are later revealed to be powered by Infinity Stones, his line about "protecting against yourself" can be understood as the Tesseract's stone not being able to overcome the power of the stone in Loki's scepter. This is shown later, when Black Widow closes the connection using the scepter.

  • 2
    Why do you think they did not use the scepter to close the portal? I distinctly recall Black Widow doing just that.
    – J Doe
    Oct 18, 2017 at 22:21
  • Sorry, for some reason I was thinking that destroying the ship with the nuke severed the portal as well. I'll remove that.
    – Mr Nick
    Oct 19, 2017 at 16:12

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