Aetherius

An aetherius (/e-ˈthir-i-ˌəs/, plural aetherii /-i-ˌai/) is a self-contained being comprised of energy, in opposition to a hyloeid which is a self-contained being comprised of matter.

Etymology
The name for these beings comes from the word "aether," which itself comes from the Homeric Greek word αἰθήρ (aithēr).The philosopher Plato considered aether to be a type of air; however, his former student Aristotle disagreed and added aether to the list of classical elements of Ionian philosophy as the fifth element, following air, fire, water, and earth. The original four elements were described as being hot or cold, and wet or dry, but Aristotle postulated that aether had none of these qualities. Over time the term became synonymous with "quintessence," the element thought by medieval alchemists to make up the heavenly bodies and which was sought after or supposedly duplicated to cure illnesses and impurities.

Classification
Because the study of aetherii from a methodical, scientific point of view is relatively new, classifying known and hypothesized aetherii by taxonomic hierarchy (as hyloeids have been classified since 1758) has not been accomplished. Scientific names for proposed genera and species are therefore not a concrete determination of the evolutionary tree of aetherii. Instead, until such data can be established, aetherii are classified by certain primary characteristics.

The initial classification of aetherii focused on three such characteristics: visibility, tangibility (now called tactility), and structure (originally referring to both shape and composition). Since approximately 2010, however, some researchers have also begun classifying by two additional characteristics, method of locomotion and uniformity which clarifies the composition of the aetherius' energy, relegating the category of structure strictly to a shape classification.

Classification is often written in shorthand with identifying letters in the order of characteristics given above. An example of this might be the shorthand for poltergeist, "IIFUV". The first "I" represents visibility and indicates "invisible"; the second "I" tactility indicates "intangible"; "F" structure indicates "fluid"; "U" locomotion indicates "unknown"; and "V" uniformity indicates "variably anisotropic". The different values of these letters are explained below under each characteristic's header.

Visibility
Visibility is defined as the measure of the amount of visual perception of an aetherius on the part of humans (or other hyloeids). In discussing visibility as regards aetherii, it is important to remember that aetherii are comprised of energy, and therefore the only way a human could actually see an aetherius is if their component energies fell within the ''visible spectrum of energy. ''These energies have a radiant wavelength from about 390 nanometres (billionth of a meter) to about 700 nanometres, or in other words a frequency of 430 - 790 terahertz (trillion cycles per second). This range of frequency is only 0.00012 of 1% of the common electromagnetic spectrum, so "visibility" is often inferred by the environmental effects of the component energies, if it can be recognised at all.
 * Invisible (I). There are no markers or indicators for the presence and location of any component energies of the aetherius.
 * Exclusively peripherally visible (P). An aetherius which exhibits exclusive peripheral visibility can only be recognised by markers visible through refraction in a human's peripheral, or indirect/sideways, vision. Also sometimes called exclusively non-foveally visible (see below).
 * Exclusively foveally visible (F). An aetherius which exhibits exclusive foveal visibility can only be recognised by markers visible through direct, head-on line-of-sight. The term refers to a part of the human eye called the fovea centralis, which is responsible for sharp central vision. It is a small divot at the back of the retina which contains a high concentration of tightly packed cone cells, photoreceptors that work best in bright light.
 * Conditionally visible (C). A variety of scenarios can cause an aetherius to be classified as conditionally visible, all of which must satisfy the criterion that there is an identifiable factor whose presence or absence changes the visibility of the aetherius from perceived to not perceived, or vice versa. The most common cause of conditional visibility is of refraction not occurring in the human eye - in other words, the energies of the aetherius cause natural refraction of light, rather than being visible only by forced refraction.
 * Fully visible (V). Visibility refers to two scenarios. The more common is a scenario in which there are clearly visible markers or indicators of the component energies of the aetherius. The extremely rare is a scenario in which the component energies themselves are visible (again, these are only energies with a frequency of 430-790 THz). While "fully visible" technically only applies to the latter, the term is still used for both scenarios compared to other visibility measures.

Tactility
Tactility is defined as the measure of the amount of tactile (touch) perception of an aetherius on the part of humans (or other hyloeids). Tactile perception is difficult to gauge because energy is constantly being touched, but not necessarily perceived, by humans. According to mass-energy equivalence, all forms of energy exhibit mass, but the mass is almost always so minuscule that it falls short of the threshold of the human brain to notice the change.

For example, the energy required to heat 1 m³ of dry air from 0°C (32°F) to 20°C (68°F) is 25.9893 kilojoules. In the process, that same 1 m³ of dry air loses mass equal to -0.088 kilograms (approximately the weight of an apple). Because the law of conservation of energy states that energy cannot be created or destroyed, we know that the lost weight is equal to the energy used.

Despite the fact demonstrated above that energy exhibits mass, there are still frequent situations when energy particles can pass through mass/matter, such as when light passes through a glass of water. Quantum tunnelling is the term for the quantum mechanical phenomenon where a particle passes through a barrier that traditional mechanics would suggest could not be breached in that manner. In these cases the energy level remains the same but the amplitude decreases during the tunnelling space-time period. Because of this, some aetherii can pass through matter and others cannot; of those that pass through matter, most are imperceptible by normal means, although some "leave behind" a reflective-wave sensation.
 * Quantumly intangible (I). The aetherius is capable of quantum tunnelling - it passes through matter with little to no interruption or separation - and its energy has insufficient mass to be perceived by humans using normal means.
 * Classically intangible (N). The aetherius cannot/does not exhibit quantum tunnelling, but still has insufficient mass to be perceived by humans.
 * Quantumly tangible (Q). The aetherius is capable of quantum tunnelling, but its energy has sufficient mass and can be perceived to some degree by humans.
 * Classically tangible (T). The aetherius cannot/does not exhibit quantum tunnelling, and has sufficient mass to be perceived to some degree by humans.

Structure
Structure is defined as the composition of functional energy relationships within the aetherius. This can be more simply explained as whether the energy that makes up an aetherius has any of the following three observable characteristics: external cuticles (equivalent to skin or membranes), identifiable viscera (equivalent to organs), and if both the previous are present, then whether or not there is a discernible design (placement of viscera relative to each other).
 * Amorphous (A). The aetherius has no external cuticles or identifiable viscera (and therefore no discernible design). It may be unclear how much of the energy belongs to the aetherius and how much of the energy is residual around its body.
 * Collective (C). The aetherius has no external cuticles, but it does have identifiable viscera which emanate from the center or core of its presence. This is best compared to the behaviour of light, which dissipates as it travels further from the source.
 * Contained (N). The aetherius has no identifiable viscera, but it does have external cuticles. As opposed to C structure, N structure has the strongest energy bonds around the external boundary (typically spherical) and weakest energy bonds in the centre of its occupying space. This is best compared to a soap bubble, which maintains most of its substance at its surface.
 * Fluid (L). The aetherius has both external cuticles and identifiable viscera which can be defined as either precise or approximate; however, there is no discernible design relating one to the other. This is best compared to hyloeid amoebae, which have their inner structures in a liquid called cytoplasm within a thin flexible outer membrane.
 * Fixed form (F). A rarity for aetherii, the aetherius has all of external cuticles, identifiable viscera, and a discernible design.

Locomotion
will have to expand on this


 * Wave oscillation


 * Bipedal locomotion


 * Quadripedal gait

Uniformity
Uniformity is defined as the composition of the component energies of an aetherius. This does not refer to the specific wavelength or frequency of the aetherius' energies, but rather to the way that multiple energies within the body of the aetherius relate to one another, and in one instance whether there is even more than one type of energy that makes up the aetherius. Studies on specific frequencies may eventually contribute to the classification of specific genus and species, if such taxonomy is ultimately used.

A graphic depiction of the five commonly accepted uniformity classifications follows the list below.
 * Singularly isotropic (I). The aetherius is composed of a single type of component energy.
 * Structurally isotropic (M). The aetherius is composed of more than one type of component energy, but the multiple component energies lay within the aetherius as a repeating pattern such as cubic, hexaprismal, or other crystalline structure.
 * Spherically anisotropic (S). The aetherius is composed of more than one type of component energy which are present in layers, such that the same progression from one type of energy to another can be indicated in any direct line from the centre of the aetherius to its outer boundaries.
 * Linearly anisotropic (L). The aetherius is composed of more than one type of component energy which are present in sequence, such that the same progression from one type of energy to another can be indicated in any direct line from a point on one outer boundary to a point on the opposing outer boundary.
 * Variably anisotropic (V). The aetherius is composed of more than one type of component energy which are present without consistent pattern or progression that can be indicated with a direct line from any one point to another.
 * Indiscernible (W). An alternative to the label of variable anisotropy, not frequently used, but sometimes referred to when it is known that multiple component energies exist but it cannot be decisively proven whether they are laid out in a repeating structure (multiple isotropy) or a random arrangement (variable anisotropy).