The AT Fields are impenetrable.

Absolute Terror Fields surround every living thing, and nothing crosses them without annihilating both the barrier and the thing inside — but Gainax didn't design them to keep people out, they designed them to keep people in, and then made the worst part psychological.

Watch Instrumentality, the Third Impact sequence where AT Fields dissolve and everyone merges into LCL fluid. It looks like transcendence — Seele wanted it to look like transcendence, the end of loneliness, the dream of total union — but the moment it happens, consciousness becomes noise, identity becomes meaningless, and the merging isn't connection, it's erasure wearing connection's mask.

Shinji's entire arc hinges on this. Every time he reaches for contact — with Misato, with Kaworu, with Gendo — the AT Field holds, not because they don't care but because they're separate beings and separateness is structural, not incidental. The N2 mines, the angel blood, the LCL tanks — all the show's imagery of forced union — they're not technological failures, they're visual proofs of a principle: you cannot merge without destroying what you are.

The horror Gainax embedded in late-90s Japan wasn't that people were alone — it was that they were spending everything, money, technology, emotional labor, psychological breakdown, trying to prove they weren't. The AT Field design says this is what you'll always hit: not a wall you can break through, but a wall that's actually you, and breaking it means you stop existing.