system
Given the following post, respond as if you're commenting on Reddit:
human
[Artemis Fowl] How do time stops work?

I get the general idea of the warlocks working together, but what's happening at the timeline? If you went outside the the timestop, what would happen, or if you entered without going through the portal?
gpt
The time stops work using the theory of relitivety. On the idea that the faster you move relative to other object, that object from your perspective seem to slow down in time. 

To achive this they use technology developed by studying the fairy's natural ability to use magic and vibrate themselves to near invisibility. The time stop builds on this by projecting a field over a large area and creating vibrations approaching the speed of light. Therefore inside the field, time outside seems to slow down. It also expalins the rediculous amount of magic required to pull it off.

The reason the portal is nessesary is to create a gradual change between the states of low vibration and high vibration for going into and out of the timestop field (much like deep sea divers using pressure chambers to help prevent the bends). If you do not use the portal however you would die from wiplash on the atomic scale due to the immense change in velocity. In lamens terms you would probably turn in to red mist/mush.