Earth is just one of many dimensions.
A dimension[1][2][3][4] referred to a self-contained reality,[1][5][6][7] plane,[8][9][10][11] universe,[2][12][13][4] realm,[8][14][15][4] and, more informally, world,[1][2][16][17] as in to "save,"[18][19] "destroy,"[19][20] or "end."[18][20]
Earth, while also the name of a planet,[21] was a dimension[1] like many others.[3] Some dimensions were parallel to each other only with a different timeline,[12] like the one created with a wish,[17] while other worlds had different laws of physics and magic, like Pylea[22] and Quor'toth.[23] Demon dimensions could cause an apocalypse on Earth each time they threatened to swallow it.[19][4][24]
Time
The flow of time within other dimensions was often different from that on Earth. For example, Angel was trapped in Acathla's dimension for at least three months in Earth time, but was said to have endured hundreds of years of torture.[25] In a dimension where demons enslaved humans in a factory, one hundred years equaled only one day on Earth.[5] Connor also returned from Quor'toth in his mid-to-late teens after having entered the dimension as an infant mere weeks beforehand in Earth time.[26]
However, this did not seem to be the case with all dimensions; for example, Winifred Burkle was trapped within Pylea for five years, both in Earth and Pylean time.[27]
Planes
Hell
- “What is Hell but the total absence of hope? The substance, the tactile proof of despair.”
- ―Ken[src]
A hell dimension, also known as a demon dimension, was a world where the conditions were hostile to the development of human life.[2][25] Demons were the dominant lifeforms in these dimensions.[4] Earth itself was once considered a hell dimension, as demons originally populated it before humans evolved and eventually drove the Old Ones and other demons out.[1]
One hell dimension enslaves humans in a factory.
The nature of hell dimensions also varied. Acathla's dimension was fiery and full of demons looking to torture anything with a soul.[2][19] The dimension where Ken ruled had humans working as slaves and deprived of hope of escaping.[5] The dimension for Jasmine's first followers had an atmosphere that was toxic to humans.[28]
Some hell dimensions had a relatively structured society; Pylea was a feudal theocratic society,[22] and Oden Tal had a monarchical government.[29] The world of Arashmaharr was home to many sociable demons, such as D'Hoffryn, who carried out their evil deeds in a business-like environment.[30]
The demonic law firm Wolfram & Hart had its own pocket dimension, a Holding Dimension for employees who betrayed the company. The dimension appeared as a seemingly idyllic suburban neighborhood, where residents were regularly tortured by a demon living in their basement.[31]
Higher plane
Cordelia in a higher plane of existence.
A higher plane was a dimension populated by ascended beings.[7]
Cordelia Chase ascended to a higher plane to do more good as a higher being,[32] and Buffy Summers and Angel were chosen to create and ascend into the dimension of Twilight.[11][7]
Afterlife
Death was often related to leaving Earth and going to another dimension. When Buffy sent Angel to Acathla's dimension,[19] she considered her act as having killed him.[33][34][35]
The deceased Lilah Morgan claimed she would be sent to a hell dimension due to the Standard Perpetuity Clause in her Wolfram & Hart contract. Rather than being subject to torture, she simply continued her employment with the company in another realm.[36]
When incorporeal, Spike began slipping into a dark place due to the machinations of Matthias Pavayne, a serial killer who had spent centuries sacrificing souls to hell to avoid going there himself.[37]
After her death, Buffy went to a place the Slayer believed to be heaven.[38]
Alternate universes
Alternate universes were dimensions existing in parallel with a strong resemblance to each other's realities.[12] Two known alternate timelines were created parallel to the Earth:
- In 1998, Anyanka created an alternate timeline when she granted a wish from Cordelia that Buffy had never moved to Sunnydale. Breaking the vengeance demon's power center restored the original timeline.[17]
- In 2002, Skip offered Cordelia a new reality in which, instead of joining Angel Investigations, she became the star of the show Cordy!. Cordelia ultimately made a deal with Skip to restore reality to normal and make her part demon to endure her visions.[39]
Interdimensional travel
There were various ways of traveling between dimensions. One was through opening a Hellmouth,[18] a mystical convergence where the barriers between dimensions were weaker.[1]
A dimensional rip leads to Quor'toth.
The barriers between dimensions could also be breached by performing certain rituals at "hot spot" locations to transport beings and objects to and from other dimensions.[22] For example, Pylea could be accessed in this way by opening portals with spells,[40] while one could only reach Quor'toth by using dark magic to tear the fabric of reality.[41]
A pan-dimensional doorway ritual was powerful enough to access any dimension.[42]
The Key had the power to unlock all dimensions at once.[43][44] In magic-based dimensions,[45] Dawn Summers, the human form of the Key, could open individual portals and destroy the barriers separating them.[46] A new rule in the Vampyr book allowed her to access her Key powers in any dimension.[47]
An artifact was the key to open a portal between the Earth and the dimension of Jasmine's first zealots.[28]
The original version of Spike's ship was capable of interdimensional travel.[48]
The Restless Door was an artifact used to create portals between any two dimensions in any location.[49]
Apocalypses
Dimensions posed a threat to each other not only with the invasion of hostile demons, but they could also cause an apocalypse each time they threatened to swallow the world.[19][44][11][24]
In 1998, Angel activated the portal to Acathla's dimension to have it consume the Earth. His blood closed the vortex, and he became a prisoner to the dimension.[19]
A portal begins to shatter the barriers between dimensions.
On the "Big Day," Glorificus and her followers performed a ritual to shatter the barriers between dimensions using the Key. Other dimensions began to alter Sunnydale with visions of demons and destruction until Buffy used her blood to close the portal.[44]
Twilight was a prophesied new dimension to replace Earth and its contents.[50] As Twilight was born, Earth succumbed to natural disasters, and hordes of "placenturian" demons were unleashed through interdimensional portals to destroy Earth and allow the passage of the new universe.[11] When Buffy destroyed the Seed of Wonder, it banished the placenturians back to where they had spilled from and ensured that the Twilight prophecy would not come to pass.[51]
The Mistress and the Soul Glutton used the Restless Door to open a portal to Anharra to allow the local demons to invade the Earth. However, they also broke the artifact and made the portal expansion apocalyptic. Dawn crossed the portal to Anharra and closed it, becoming stuck there.[24]