Alterran science has been able to identify and probe 7 different many more exist remains uncertain, though the Aetheria have hinted of four more known to them and not the Alterra.

List of DimensionsEdit

  • Midgar is the dimension that humans are aware of. It consists of the visible universe, the three spatial dimensions that we know and can see naturally.
  • Alfleheym is the dimension that ascended beings inhabit.
  • Jotunheym is the dimension inhabited by the Aetheria. They are the only intelligent species that exists in this alternate dimension. To the SGC, they are known as the Crystal Skull Aliens. The aliens that Daniel Jackson's grandfather Nicholas Ballard, stayed with to learn from and teach.
  • Muspleheym exists as a gigantic medium. No gravity wells, or any large constructs exists within this dimension. It resembles one extremely large ocean that the inhabitants swim through. The medium is dangerously active almost like a fire, it is inhospitable to matter entering from Midgar.
  • Nifleheym is a dimension in which matter of any type could not exist. Matter instantly reverts back to whichever dimension in originated from. A protective ‘bubble’ can be established around the matter, keeping it artificially within Nifleheym. A controlled environment must be maintained for living beings, no matter means no air. No matter also means nothing to rub against, in other words, no friction. Many races use this alternate dimension to their advantage on a daily basis. Nifleheym is more commonly referred to as ‘hyperspace’.
  • Svartalheym is a dimension similar to Midgar. It is filled with matter that reacts destructively with matter from Midgar, essentially it is filled with “anti-matter”. The Alterra had been working on two different projects when the plague ravaged their population. They were trying to create energy-based dampeners to insulate matter from Midgar. With these dampeners, the Alterra could establish footholds within this dimension. They were also trying to create an alternate power source by capturing and containing the “anti-matter” to use in specially constructed reactors.
  • Maneheym is a 'half-dimension' closely associated with Midgar. Objects and lifeforms within Maneheym are parasites in that they use Midgar's geography without interfering with it. The Alterra created a device that allowed the user to perceive Maneheym while still having no physical contact with it. This device was later discovered and mistakenly activated by SG-1, causing a brief, minor outbreak of 'hallucinations' within Colorado.