Appears in Episode: 21
The Sē Theory (an abbreviation for Super Solenoid Theory) is a fictional theory of energy generation advocated by Dr. Katsuragi (Misato Katsuragi's father) since before the Second Impact.
When first published, Dr. Katsuragi and his theory were ridiculed as absurd. He was eventually proven correct with the discovery of Adam, the First Angel, at the South Pole in Antarctica. Dr. Katsuragi led the expedition to study Adam (a being seemingly made of light), and later died during the catastrophe of the Second Impact.
Dictionary.com definition of Solenoid: A cylindrical current-carrying coil of wire that acts as a magnet when electrical current passes through it.
Based on Neon Genesis Evangelion Platinum: 06 DVD Booklet