Pale is a phenomenon present in the world of Elysium.
The world of Elysium is distinct 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 interisolary mass, at a ratio of 2:1 to matter.
The phenomenon covers 72% of the known surface of Elysium, interfering with any attempts at orbital flight, and protruding in gray flares, prominences, and arching over isolas. The Occident-Revachol-Graad nations have been conducting experiments with weather balloons in the lower ionosphere since the thirties, resulting in the image of "A dark grey corona, a rarefied envelope of matter surrounding the darkened disc of the planet".
The Pale does not have a perceivable appearance. It is achromatic, odourless, and featureless, the "enemy of matter and life". Therefore, it can only be measured through the matter that surrounds it. Where matter borders the pale, the resulting border is an uproar of matter, evaporating into the pale, considered "a great vision". The area of transition between the world and the pale is called "porch collapse": a grey mist with cold vapour, known to house a specialized form of fungal microorganism.
Pale is difficult to describe and measure, as it is 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 ever passed the number barrier since the discovery of the pale and it may be impossible. 
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 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: the Insulinde, the "freckled face of god".
Their travel was made possible by the fact that, using a device known as a pale latitude compressor, is possible to force dimensions on the pale, 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 fewer 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 cross from near pale to far pale.
Over-radiation, caused by prolonged exposure to the pale, 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. Workers who transport goods through the pale are known as paledrivers, and some experience overradiation through vivid flashbacks, living out past memories from lives that may or may not be theirs.
In order to transmit radio signal between isolas, a number of pale-based repeater stations are needed, though working on those is said to be an incredibly dangerous and mentally taxing job. On occasion, signal that is routed through the pale gets mixed up, sending instead conversations recorded elsewhere or years ago. In exceedingly rare cases, the pale may transmit information from the future. 
There are also 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, such as Volta do Mar, which resembles the process of writing poetry.
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.
Some consider isolary entroponetics, that is, the idea of pale being able to form from inside an isola, a hoax. However, the phenomenon is proven, one example being the point of origin inside the Dolorian Church of Humanity in Martinaise, and appears to be under investigation by the Moralist International.
The exact origins of the pale are unclear. Logical positivists claim the pale exists as pockets of anti-matter, capable of damaging and confusing the mind through extreme sensory deprivation. Dialectical materialists, on the other hand, say that it is composed of manifested information, or manifested past, capable of degrading memories into itself. The Insulindian Phasmid, speaking to Harrier Du Bois, supports the later interpretation, referring to it as a "human pollution", and claiming that every animal and plant is scared of humanity for it, believing it will destroy them all.
- JOYCE MESSIER - "Okay." She concedes. "The pale is the most dominant geological feature of the world, detective -- the separative tissue between the isolas. It is the interisolary mass."
- JOYCE MESSIER - "The pale outweighs reality two to one -- there is more pale than there is matter. And the ratio is slipping."
- JOYCE MESSIER - "Yes." She pauses. "Pale covers 72% of the surface. 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."
- JOYCE MESSIER - "There's a steadily increasing trickle of images. Between the big three scientific contributors, they're piecing together a dark grey corona."
- JOYCE MESSIER - "They say there is a rarefied envelope of matter surrounding the darkened disc of our planet. That is, if we are still living on a planet. Or, to speak more plainly, imagine vast swathes of land disrupted by nothingness."
- JOYCE MESSIER - "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."
- YOU - "I can't even understand how we're talking about something that doesn't exist, let alone measure it."
SOONA, THE PROGRAMMER - "You measure it by its surroundings -- by that which does exist," she replies, "which is what I've been trying to do. I've tried using hydrotransducers to record the silence -- to find out where it *begins*."
- JOYCE MESSIER - "An uproar of matter, darling, *rising* into the pale. Rolling. Evaporating even, a great vision. The area of transition between the world and the pale is called *porch collapse*."
- JOYCE MESSIER - "Imagine a grey coronal mist, cold vapour, marked by spores of an opportunistic microorganism -- a mould that's adapted to grow at the edge of the unrest. It's..."
- JOYCE MESSIER - "It's difficult to describe -- or even measure -- something whose fundamental property is the suspension of properties: physical, epistemological, linguistic..."
- JOYCE MESSIER - "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. It may be impossible."
- JOYCE MESSIER - "Precisely. One of the few measurable effects of the pale is that it is expanding at an unknown rate."
- JOYCE MESSIER - "The pale was thought to be impregnable, perpetual." She points northwest. "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 did, but had lost their minds."
- JOYCE MESSIER - "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 begun to condense, day after day, hour after hour, minute after minute."
- JOYCE MESSIER - She nods. "The phenomenon has never again been encountered. For a time the crew thought they were experiencing a hallucination. The mast-hand proclaimed 'L´Insulinde! L´Insulinde!' -- the signal to wake up."
JOYCE MESSIER - "But they could not. They were sane and conscious, as islands began to appear on the horizon... There are 78,000 uninhabited islands in the Insulindian archipelago, officer. The freckled face of god," she smiles.
- RUBY, THE INSTIGATOR - "A pale latitude compressor is used to sort of... make the pale more manageable. With a lot of these, you can force a radio signal grid on the pale -- literally crunch the distance across it."
- JOYCE MESSIER - "Nothing. We remain powerless before the pale. The only real advance in pale transit is the speed with which an aerostatic craft can pierce it. Less exposure leads to less... *effects* later."
- JOYCE MESSIER - "Hybrid airships, detective. Conventional rotors or jet engines no longer add velocity after the point of reference for motion is suspended -- once you've crossed from near pale to far pale..."
- JOYCE MESSIER - "It feels terrible. Absolutely terrible. International standards strictly limit civilian travellers to six days of pale exposure per year..."
- JOYCE MESSIER - "No, Lieutenant Du Bois. I'm 'Entroponetic Business Class.' I'm cleared -- and trained -- for 22 days of pale transit annually."
- YOU - "You're a paledriver. You transport goods through the pale."
- RUBY, THE INSTIGATOR - "Signals are relayed across a series of repeater stations fixed to buoys." She pauses. "Not a fun job, manning those stations. All alone out there in the pale, people lose their minds in just a few years."
- SOONA, THE PROGRAMMER - "It's quite common actually. When the signal gets routed through pale, all kinds of irregularities take place. You may hear snippets of someone else's conversation, or the voice of your former lover, or an echo of an event that took place 100 years ago."
- KIM KITSURAGI - "I didn't say anything, detective."
KIM KITSURAGI - "...someone has been maintaining it. The wiring has been repaired..."
HORSEBACK ANTENNA - An uncomfortable silence falls over the connection.
KIM KITSURAGI - "... It's been a long winter... Long and cold..."
- CUNO - Cuno puts his hand on the generator. "This shit's cold."
INLAND EMPIRE - N-n-n-no. This isn't right...
YOU - What's the matter?
INLAND EMPIRE - 'It's cold now,' he was supposed to say. 'But someone has been maintaining it. The wiring has been repaired'...
INLAND EMPIRE - But he's not here to say it. Something *else* got in the way. Events *intervened*...
- JOYCE MESSIER - "There *are* signs of pretermodern crossings. Successful navigation of the pale relies not just on technical know-how, but intensive psychological preparation. Some of these tactics have been known for thousands of years."
- JOYCE MESSIER - "The same strict psychological regimen the eighth admiral developed when he crossed the pale and discovered this isola -- the *Volta do Mar*. It's used by interisolary travellers and other troubled souls even to this day."
- JOYCE MESSIER - "Until after *years* of trial and error -- and the development of a *strict* psychological regime imitating the creation process of poetry..."
- JOYCE MESSIER - "*Entroponetics*," she corrects, "is the scientific study of the pale. Or a recent iteration of it, by way of Graad. The study of the pale reaches back 6,000 years -- the Perikarnassians called it the Western Plain."
- RHETORIC - They had not travelled the entire circumference of the Perikarnassian super-isola. It was not merely in the West -- it was everywhere. Even then; surrounding them...
- JEAN VICQUEMARE - "Thank you, Lieutenant Kitsuragi. Just to clarify -- I do not think isolary entroponetics are a hoax. Pale produces global phenomena -- it's proven. However..."
- YOU - "I said, 'I've discovered an entroponetic phenomenon here in Martinaise'."
COALITION WARSHIP ARCHER - "Acknowledged. Listen very carefully, Firewalker. We are going to ask you a series of questions. It is imperative that you answer as directly and truthfully as you can. Do you understand?"
- JOYCE MESSIER - "Some say the damage stems from extreme sensory deprivation. Others argue that pale somehow *consists* of past information, that's degrading. That it's rarefied past, not rarefied matter."
JOYCE MESSIER - "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."
YOU - "Who says and who argues?"
JOYCE MESSIER - "The logical positivists say -- the dialectical materialists argue."
- INSULINDIAN PHASMID - The pale, too, came with you. No one remembers it before you. The cnidarians do not, the radially symmetricals do not. There is an almost unanimous agreement between the birds and the plants that you are going to destroy us all.