It’s a game.
The power was never off. That’s why the lights and everything else in that area was on. The only thing Gordon did was start the testing sequence. And, magnets don’t need power 
What a useless discussion…
Please continue
Why do you even bother with that, Explain how aliens can come from another dimension. NOW.
magic
They let out a big fart full of magic. The green color you see is actually their gas. Purple for Race X aliens. 
Electromagnets do, idiot. Which is what they use in real mass spectrometers.
The magnets are powered by the hot gases expelled from fans when describing things like how unrealistic a video game concept is or weather or not a part of the game is “canon”
It’s a good thing they’re using an anti-mass spectrometer, then.
Hey, they could use a zero-point energy field to hold em’ up!
fix’d