Aether (DET)

This refers to aether in the Dual Earth model.

History
The term aether has historically been used to refer to a medium that exists above the Earth's atmoplane. The best known example is luminiferous aether, posited as the medium that distributes light in the same way sound requires air or matter to be spread. The Michelson-Morley experiment is viewed by mainstream science as a refutation of the concept.

However there are other notions of aether. Albert Einstein used to use the word to refer to what is now known referred to as spacetime historically, adjusting an existing term in an outdated model to serve for the new one. This is common scientific practise; the idea of atoms for example dates back to Ancient Greece and atomism, with tenets and postulates that bear no similarity to modern atomic theory. The basic idea, that of the fundamental building blocks of matter, was common.

In the same way, referring to the universal medium of spacetime as aether made perfect logical sense for Einstein.

Properties
Aether is, as Einstein defines it, the fabric of space. Its existence has been well-documented, such as in the Hafele-Keating experiment among others which prove conclusively that space is not merely a dimension and direction, but something almost tangible in its own right, that is not homogeneous and uniform.

It departs from Einstein's conception by appending the notion of concentration. Rather than just being, as the common analogy goes, a blanket that can be curved, various locations of spacetime have different thicknesses. This can also be understood through the lens of stretching; if the aforementioned blanket is elastic then some parts could be stretched thin while others remain compressed. The stretched parts would appear significantly thinner.

The consequences of thicker locations are well understood. Two objects may have a fixed distance between them, and the more space there is between them, the greater that distance is, and vice versa.

Two objects may appear to move closer together, even if they were completely stationary, should the aether or space between them grow thinner.

This may be viewed as similar to a spring. The length along the coils of a spring is constant, but the spring itself can be stretched or compressed and five identical springs could be compressed and laid end-on-end while a stretched out spring would cover the same distance as five others. If you were limited to travelling along the coils however the distances would not seem the same.

Flow
Universally it is noted that, in the absence of external forces, objects flow from areas of high concentration to areas of low concentration. This is observed with diffusion, free expansion of a gas, the second law of thermodynamics, osmosis, among many other areas, covering both mattery and energy.

The same is held as true about aether. Thus thicker areas, higher concentrations, will tend to disperse and flow towards lower concentrations. As a frictionless medium, too much might flow and need to be corrected for, causing more aether to flow into the location where the high concentration used to be.

Any object occupying a fixed point in space would move with this fixed point.

It is not the case that this would necessarily lead to equilibrium. It was proven by Alan Turing in 1952 that diffusion and diffusion-like behaviors may form so-called Turing Patterns, repeating cycles and shapes rather than uniformity.