I've decided to make an explanation blog for the cosmology of the Danny Phantom verse. Since the graphic novel has been out for a bit now, I think it's time we evaluate to cosmology with information from the original cartoon and the graphic novel.

Original World

It is revealed^[1] that in the beginning there was nothing and everything, and all worlds were one along with everything else. Disharmony struck and a war that resulted in a divide that split the world in two and the spirits were ripped from the earth. All the emotions and energy the physical world could not hold belong to the spirit realm.

So in the begging everything was one but a war resulted in a divide that split the original universe in two which are the human world and spirit world (mainly known as the Ghost Zone), which will be gone into below.

Ghost Zone (Spirit World)

The Ghost Zone, also known as the spirit world^[2] or spirit plane^[3], is one of the two worlds created from the divide. The Ghost Zone is shown to be made entirely of ectoplasm at various points in the series and stated by the creator of the series to be an "endless void of ectoplasm"^[4].

It's stated that by Frostbite that the Ghost Zone is constantly shifting in time with portals to the human world opening in one time period and then leading to another (Here's the video with sound)^[5].

We also are told that the Ghost Zone is a flipside of the human world's plane of existence and is apart of the entire dimensional structure and if one gets destroyed, so does the other (with earth being the connection to the Ghost Zone)^[6] which was also re-told this by the creator of the series using the clip from the episode^[4].

The Ghost Zone is Infinite

As I mention above, it is stated by the creator of the series to be an "endless void of ectoplasm"^[4]. This would mean the Ghost Zone is infinite, and is supported in verse when Skulker stated there are infinite realms within the Ghost Zone^[7]. One of the later episodes revolving around traveling through the Ghost Zone is even titles "Infinite Realms" so it's not just some throw away line and they want us to know it has infinite realms in it^[5].

Despite there being infinite realms that also consist of timestreams of infinite size in the Ghost Zone (see the "Infinite Realms and Time Streams" section below). We still see areas with no realms in sight^[8], proving that the Ghost Zone's endless space is a greater infinite than the infinite realms.

Infinite Realms and Time Streams

As mentioned above, there are infinite realms within the Ghost Zone. These realms vary in size, with some being homes created by ghosts that are as small as rooms^[3], while others are big enough to hold celestial bodies such as suns^[9][10]. These realms have their own time flow as shown with the realm Poindexter is from, it and all it's inhabitants are stuck in the black and white 50s era^[2], and in Dorathea's realm everything was stuck in the 1600s until time started to move again^[9].

While the above wouldn't have been enough to suggest actual space-times, in the graphic novel, Dark Danny attacks Clockwork and decides to consume him (Overshadow) in order to gain his power and become unstoppable. He later releases an "atomic bomb level" energy readings and begins tearing a hole in the Ghost Zone that would eventually cause it's destruction. It's then stated that the time glitches they are experiencing are do to the unstable fusion of Phantom and Clockwork, and it's time apart and will cause reality to explode. To back up the effects he was having on time further, each time they hit Phantom, reality got more unstable, with it being stated reality is dissolving because of him.

This was shown even affecting the realms inside the Ghost Zone while Danny and co were inside Pariah's Keep, and when Clockwork transports everyone to the Ghost Zone, he explicitly states Dark Danny damaged multiple time streams and he needs to compress them to stabilize reality^[1]

You can see they are referring to the realms (the purple doors) within the Ghost Zone and thus means the Ghost Zone contains an infinite number of realms which included literal space-time continuums within itself as "timestreams" mean other space-times continuum because when Vlad approached Clockwork about resetting his life back, Clockwork states it will affect the timestream which obviously means the timeline. These timestreams are also proven to be infinite is size, as Clockwork compressed the remains of several corrupted timestreams into stable timelines of the Human World^[1], which is infinite in size.

The Human World (Universe)

The human world in Danny Phantom is one of the two worlds created from the divide. is similar to our universe in a way, having all the planets in our solar system and stars (That's Vlad in outer space for context)^[11].

It is connected to the Ghost Zone in the same way as the Ghost Zone is connected to it, however unlike the former, Earth is the anchor point which is destroyed, destroys the entire Ghost Zone as mention in the final episode of the series^[11] and retold by the creator^[4][6].

The Human World is Infinite

By default the universe would've be the same as ours, but in the final episode of the series, Danny, Sam, and Tucker return from outer space and have a conversation with Danny claiming their is infinite darkness in outer space^[11]. Given he's consider a space nerd, this statement might have some backing and considering that it's the flipside of the Ghost Zone's plane of existence^[4][6] which is infinite in size and contains infinite realms within it. It's safe to assume that it's flipside is also infinite and would be capable of containing an infinite number of realms/timestreams within it.

Conclusion

1. Everything was once one until the world was split into two (Human World and Ghost Zone)

2. The Ghost Zone is an infinite sized space-time continuum that contains an infinite number of realms/timestreams, making it a 2-A structure.

3. The Human World would also be considered a 2-A structure since the original universe was divided into two and both the Ghost Zone and Human World are described as two sides of the same coin and both are infinite, so if the Ghost Zone can hold infinite realms/timestreams within it, then it's flipside counterpart would be the same in structure size