On the Problem of Light
The light of the star Selevati trickles into the Manifold Sky at every point in space from the Celestial Realms that lie beyond the five known dimensions. The actual point at which a given photon appears is random, but the effect is that every given volume of space in the world has an ambient light to it. Daylight and moonlight are intensified into their terrestial strengths by addition over the volume of space. As a result of this ambient lighting effect, some light inevitably gets through even in places completely shut off to the outside world or encapsulated in the shade of larger objects. This matter of physics has important practical implications for creatures and technology throught the Manifold that might require darkness to function, and a number of different techniques are employed across these domains to overcome these implications. A few examples are listed below.
Animal VisionFor most animals found in the Manifold, visual perception takes place in specialized structures: eyes. These structures serve to direct light onto photosensitive cells so that the nervous system of the animal can detect and respond to visual stimuli in a coordinated manner. Images are formed in eyes when light bounces off of an object or is otherwise directed into the eye, conveying information about the shape, color, and proximity of those objects. Vision in the Manifold presents a special problem, however, because some limited number of photons cross the hidden fourth and fifth spatial dimensions to appear at any point in three-dimensional space - including, potentially, within eyes. This serves to confuse visual perception by adding 'noise' to an image, partially crowding out naturally reflected or refracted light from the exterior environment. Animals in the Manifold have adapted to the presence of universal ambient light through the process of evolution. Like with other sources of radiation, reaction cross-section is an important factor with regards to ambient light; the smaller the eye, the fewer stray photons will appear within it to confuse an image, and the less an image will be 'jammed' by the whims of quantum probability. The practical upshot of this fact is that eyes and similar implements (i.e. telescopes) have a maximum useful size. Additionally, because certain environments experience ambient lighting in different spectra (i.e. the intense infrared and ultraviolet of the Distal Tesseract), it is also possible for creatures to evolve vitreous humor chemistry that absorbs the most intense spectra while remaining transparent to others. Polarizing iris shapes (i.e. on the golden skirt cuttlefish and many ovinex can further help the creature distinguish between light reflected off a surface and defuse ambient light.
Sleep & Other Biological CyclesRelated to the issues presented by ambient light for visual perception is the fact that light levels have a strong effect on the circadian rhythms of creatures. Animals might be active during the day (diurnal) or night (nocturnal), resting during the opposite period to recover their strength, hide from predators, or manage heat and cold. For plants, darkness can be a time to complete the metabolic cycle, and changes in the lenght of the day-night cycle can herald flowering, seeding, or hibernation among other seasonal processes. In response to ambient light, most living things in the Manifold have developed higher thresholds for responding to light than those same creatures would have in their pre-Curved Time forms. For plants and other non-enervated species, this might involve darker and more opaque coloration so that light must be more intense to penetrate.
PhotographyIn film cameras, light is focussed through systems of lenses to project an image onto a chemically-doped cell of polymer or celluloid. The chemicals in this cell darken in response to this light, creating a negative; chemical processes are later used to develop the film to create a permanent image. Stray light in storage or during the development process can ruin film. Unfortunately the very air in the Manifold Sky is soaked in a thin ambient glow, making film expire quicker and increasing the difficulty in controlling exposure. Camera and film designers have come up with several clever ways of overcoming this problem. First, special coatings and shapes can be used to reduce the amount of ambient light that successfully reaches the sensitive film. For example, blocks of dark-colored soundproofing foam with convoluted surfaces can serve to diffuse light as well as sound, reducing glare and evening out ambient exposure. Baffles around and between the coils of film create unilluminable areas, reducing the ability of ambient light to self-amplify. As with eyes, smaller sizes means less opportunity for stray photons to spontanously appear within the same space as the film. Efforts are underway to develop either photosensitive compounds that can be stored as binary reagents up until the last possible moment or, alternatively, storage compounds that arrest photosensitive reactions until removed when a photograph is to be taken.