Dimensional Anchor Theory

The Dimensional Anchor Theory was a physics theory espoused by Oxford scholar Leila Mehri in 1983 during her fellowship at Miskatonic University. While rooted in anthropology, her studies of the Chepachet tribe, a lost branch of the Massachusett that lived in what is now Arkham pre-colonization, led her to interact frequently with Allison Marie Flynn, a physics PhD candidate at Miskatonic, creating a mixed physics-sociological theory. It stated that all organic beings are bound to their home dimensions through their understanding of it, and that the anchor created by this understanding made traversal between dimensions difficult if not impossible.

Theory
Understanding that the portals found in Arkham and exacerbated by Ms. Flynn's experiments led not to different parts of the universe but to a different dimension all together, Ms. Mehri also surmised that organic beings would not last in different dimensions. That is not because of differential physics in and of themselves, but rather individual physiology adapts to and can only understand a given universe, thus creating an "anchor" for it. The greater the anchor, the greater the hold of the home dimension on the individual.

The impact of this related to the ability to traverse between dimensions. The greater the anchor hold, the shorter amount of time an individual had to function in a different dimension, and vice versa. This meant that smaller creatures were able to exist in different dimensions with minimal fuss, while larger creatures would struggle to last more than a short time.

Sentient beings, such as humans, would struggle significantly to traverse dimensions, and would not last more than a few minutes in this different dimension. Repeated exposures to these other dimensions could stretch the length of time to at least a week, but no more than that without causing significant psychological damage.

More powerful beings, such as gods, are so anchored into their home dimension that traversal between different dimensions is impossible. Even the lowest level god would not last more than a split second in the new dimension.

Exceptions
When Ms. Mehri encountered Marisa von Teudt, both in Arkham and in the other dimension, she recognized the possibility of exceptions to the theory. The first came in the form of Ms. von Teudt, who was not fully human but the hybrid offspring of a human female and a Muklmin breeder. By being the composite offspring of two parents from different dimensions, her physiology could adapt to both dimensions without fuss. However, the mental impact remained.

Based on encounters with Leslie Kukosz, a young human woman who disappeared from Arkham in May 1982, Ms. Mehri included another exception. It is possible that, like an anchor on a boat, a sentient individual could theoretically move their anchor to another dimension, at the cost of severing most - if not all - connections with the home dimension. Such a move requires a mental detachment from the home dimension. For humans, this can take the form of disillusionment with society, absence of strong social connections (such as family and lovers), and a desire of complete abdication of one's current responsibilities. It can also take the form of a strong belief that the world in its current form will collapse, or that society will disintegrate.

Ms. Mehri ultimately used the exception of this theory to identify the fate of the Chepachet in her dissertation: Upon realizing that European colonization would destroy their small tribe, either through violence or disease, the tribe crossed dimensions with the intent of never returning.