Y g g d r a s i l
In the universe of AMG there is one thing which is central to it all: Yggdrasil. Now I could have simply put this under the more generic "Norse Mythology" section, except that Yggdrasil is so complex that it requires a fair explanation.
Yggdrasil manages reality. In Norse mythology; the world will continue to exist as long as Yggdrasil continues to grow. Whatever metaphor for Yggdrasil you use (computer or tree): Yggdrasil is to some extent the bond that ties the entire universe together. What the exact relationship between Yggdrasil and reality is, is never really specified - although it's sort of hinted that the universe only continues to exist because Yggdrasil manages the inner clockwork that makes everything work. Somehow this doesn't exactly cover all the bases either. For instance, the Lord of Terror decided to cut to the chase and simply cut the 10 dimensional string (of the universe) - leading one to believe that reality comes before Yggdrasil, not the other way around. Of course cutting a 10 dimensional string doesn't make sense anyway since the string is reality itself; how do you cut all the way through reality if you exist in it? For that matter WHERE does a 3(4) dimensional being swing a 10 dimensional blade? (think about it). But I won't nit-pick too much, it just bugs me =P
Yggdrasil is a tree. With a direct tie in to Norse mythology, Yggdrasil has all the components of a plant: branches, roots and so forth. Yggdrasil begins at the Earth, with its roots trailing into the lower realms (the under world and such), and it's branches extending into the heavens. While Yggdrasil isn't necessarily a tree that you can see and carve your initials into, it does exist on Earth, and CAN be cut down - although this requires special circumstances.
Yggdrasil is a computer - or to be more specific: THE computer. It's not just a computer that runs by itself, but is instead a mainframe which requires constant attention of various attendants. Again the Goddesses seem to assume responsibility over all this, while the demons tend to slack off. While the tree metaphor for Yggdrasil is pretty shallow (usually just for plot purposes: "Yggdrasil is a tree, I'll cut it down" type of plots), the computer metaphor gets a LOT deeper and extends into other aspects of AMG. Confused yet? Too bad, now we get into advanced AMG universal theory!
Yggdrasil essentially controls everything, and the goddesses manage Yggdrasil. Access is not unlimited however, and each goddess is only allowed as much access as her license permits. Like with the angel system, this looks a lot like it tips the balance between goddesses and demons in favor of the goddesses who directly interact with Yggdrasil. It might be possible that demons also attend Yggdrasil at the root of the tree, but I probably won't be able to comment on that until I get the issue of AMG where Hild appears. The balance could also somehow be covered in the doublet system.
As Arthur C. Clark once said: "Any sufficiently advanced technology is indistinguishable from magic". Magic in AMG is really an interesting thing. The goddesses don't really talk in terms of spells, they instead usually refer to using their powers as initiating some sort of program. (There is a shift to the more computer centric world later in the manga. Earlier on, magic was more... well, magical). Like the rest of the inner workings of Yggdrasil, goddesses require special privileges to access certain programs. Goddesses seem to have general purpose programs ready to use at their fingertips. Advanced/special-purpose programs seem to require a special calling sequence in the form of some incantation - usually indicated by a goddess talking with some rather frilly font in the manga.
Like any other major computer system, Yggdrasil can be hacked. Generally this means stealing privileged programs allowing one to use advanced spells that they normally couldn't, or somehow interfering with Yggdrasil's normal routines.
So just how do you pronounce "Yggdrasil" any damn way?
With four consonants in a row, this is sort of a tricky one for English speaking people to figure out. The 'y' is actually pronounced as a short 'i'. (the 'a' and second 'i' are also short). Yggdrasil should be pronounced ig' dra sil with emphasis on 'ig'.