Pale is the connective tissue between the isolas of Elysium.
The world of Elysium is unique in that it is not a single contiguous landmass, but consists of vast continents of matter - isolas - surrounded by a separative tissue. This tissue is called the pale and is the most dominant geological feature of the world, the inter-isolary mass, at a ratio of 2:1 to matter.
In fact, it covers 72% of the known surface of Elysium, interfering with any attempts at orbital flight. The Occident-Revachol-Graad nations have been conducting experiments with weather balloons in the lower ionosphere since the thirties, and managed to put together a rather startling image: A dark grey corona, rarefied envelope of matter surrounding the darkened disc of the planet. That is, if Elysium can still be considered a planet: Imagine vast swathes of land disrupted by nothingness. There are grey flares and prominences, even arcs above entire isolas... The images are blurry, but if there was a sphere in there it certainly looks like it fractured a long time ago.
What does the pale look like? It's achromatic, odourless, featureless. The pale is the enemy of matter and life. It is not like any other -- or any thing in the world. It is the transition state of being into nothingness. Where matter borders the pale, the resulting border is an uproar of matter, rising into the pale. Rolling. Evaporating even, a great vision. The area of transition between the world and the pale is called porch collapse: A grey coronal mist, cold vapour, marked by spores of an opportunistic microorganism.
Pale is difficult to describe and measure, as it's something whose fundamental property is the suspension of properties: physical, epistemological, linguistic. The further into pale you travel, the steeper the degree of suspension. Right down to the mathematical -- numbers stop working. No one has yet passed the number barrier since the discovery of the pale and it may be impossible.
In fact, one of the few measurable effects of the pale is that it is expanding at an unknown rate.
The pale was thought to be impregnable, perpetual. Irene La Navigateur, the Queen of Suresne, sent eight expeditions, one after the other, into the mass at the edge of the world. Five of the crews did not return. Two others lost their minds. After years of trial and error and the development of a *strict* psychological regime imitating the creation process of poetry the eighth expedition returned -- sane and intact. They told of a new continent of matter. They told the queen and her councillor, Dolores Dei, that the pale had began to condense, day after day, hour after hour, minute after minute, leading to the discovery of a new isola.
Their travel was made possible by the fact that is possible to force dimensions on the pale and in modern times humans can even compress its latitude, bouncing radio waves from one end to the other and shortening the path. However, the only real advance in pale transit is the speed with which an aerostatic craft can pierce it -- less exposure leads to less adverse effects later. Aerostatics are hybrid airships, necessary as conventional rotors or jet engines no longer add velocity after the point of reference for motion is suspended once they crossed from near pale to far pale.
However, it is still hard for humans to navigate the pale without getting lost or suffering mind damage. Some say the damage stems from extreme sensory deprivation. Others that pale somehow consists of past information, that's degrading. That it's rarefied past, not rarefied matter. They call it the blend-over of the self -- the pale does not only suspend the laws of physics, but also the laws of psychology; maybe History, even -- the human mind becomes over-radiated by past.
Overradiation is a horrible feeling and international standards strictly limit civilian travellers to six days of pale exposure per year. Members of the Entroponetic Business Class are specifically cleared and trained for 22 days of pale travel annually.
Notably, there are signs of pretermodern crossings. Successful navigation of the pale relies not just on technical know-how, but intensive psychic preparation. Some of these tactics have been known for thousands of years.
Entroponetics is the scientific study of the pale. The pale has been studied for thousands of years in one way or another and the most recent iteration of it comes from Graad. The study of the pale reaches back as far as 6,000 years, to the Mundi isola and the Perikarnassians, who called it the Western Plain. They had not travelled the entire circumference of the Perikarnassian super-isola and assumed it was simply a feature of the west, not yet aware of its omnipresence.