User:Ghelæ/Guide To Stuff

Welcome to Ghelæ's Guide to Stuff, the successor to the far more useful and world-renowned Ghelæ's Guide to Battle Images! Over the coming millennium or so, I intend to fill out this page with useful stuff that can be useful for building a realistic fiction, and isn't specific to the main collaborative SporeWiki fiction univese. Useful, don't you think?

Matter Manifestations
In physics, it turns out that the concept of "stuff" is actually quite abstract. However, most people still find it quite useful to think of the universe in terms of matter. This section is about basic physics and the resulting technological applications.

Preliminary information
Although it's not necessary, it helps to understand a bit of fundamental physics in order to make sense of the applied parts - and to figure out what other things might be possible.

 »»»= Laws of Physics=

The basic principles from which physical phenomena arise are known, somewhat poetically, as the "laws of physics". These fit into two main groups. The first, the symmetries, describe spacetime itself and provide order to the universe. Secondly, there is the field content, which describes the different types of structures that can exist in the universe. This preliminary section will deal with the first group; the second will be addressed in the "Particle" section of the main list.

Symmetries are features that, when changed, leave a physical system unaltered. The most obvious symmetry is that which describes spacetime, setting three bidirectional dimensions of space and one unidirectional dimension of time, with a speed c as the conversion factor between units of the two quantities. This speed must be the same for all observers, which results in several "relativistic effects" (named for the principle of relativity, that motion is relative: the laws of physics are the same for all observers, regardless of how fast they're moving) that play a vital role in the universe, but are utterly counterintuitive for minds that evolved in a low-velocity world, such as time dilation, length contraction, and relativity of simultaneity.

One intrinsic capability of spacetime is the formation of oscillations (waves), the mechanics of which are described by quantum physics. One relativistic effect is that, for quantum waves, there is a close connection between the number of oscillations in a given time (frequency &omega;), the number of oscillations in a given distance (wavenumber k), and velocity. This results in the existence of energy (E = ħ&omega;, where ħ is the reduced planck constant), momentum (p = ħk), and mass (m). Mass, or inertia, is the quality that an applied force results in a change in velocity, and is a property of any wave that (by whatever means) has energy even when it is not moving.

Without mass, waves travel at c, with E = |p|c. As light is composed of massless waves, c is commonly referred to as the "speed of light". With mass, E = mc2 when the speed is zero, but time dilation and length contraction respectively mean that energy and momentum increase with velocity, tending to infinity as the speed approaches c. Or, in other words, velocity tends towards c as energy and momentum are increased; this would also hold for waves that naturally travel at faster-than-light speeds (although it turns out that these "tachyons" are not actually possible), with velocity decreasing as energy is increased.

The most important consequence of symmetry is that, for any symmetry, there is a conserved quantity that quanta can carry associated with this symmetry. Combined with relativity of simultaneity, this results in continuity: the amount of a conserved quantity within a given volume of space can only change by passing through the boundary of that volume; in other words, teleportation (in the sense of moving between two locations without traversing the space between them) of anything with these properties is impossible.

For spacetime, invariance under time translation results in conservation of energy, invariance under translation in each of the three spatial dimensions results in conservation of momentum in each dimension, and invariance under rotation results in conservation of angular momentum (where orbital angular momentum is L = r x p, where r is the radial displacement; spin angular momentum is a dissimilar quantum effect but still connected to rotational symmetry). Other symmetries relate to "charges", the strengths of interactions between different quanta. There will be more information about these along with that of the universe's field content in the main list.

Further application of mathematics to these basic laws of physics results in many phenomena occuring with predictability, even though these are not fundamental components of the universe. Some of them are quite simple: for example, length contraction causes force-carrying fields to be split into distinct "electric" and "magnetic" components, the latter only being produced by, and acting on, moving charges. More complex phenomena arise as a result of emergence via principles such as statistical mechanics and chaos theory. At its most simple, this leads to other branches of physics such as thermodynamics; at its most complex, it requires entirely distinct fields of science such as astronomy and biology. Imponderable fluids=

There is a common misconception that the history of science primarily involves old theories being proved to be wrong and replaced with new theories, which themselves are likely to turn out to be completely wrong as well. This is not true: since the testing and overturning of prescientific ideas such as Aristotelian philosophy, any widely-accepted theory tends only to be wrong in the sense that it is limited; it simply does not tell the entire story, and only extrapolating the theory beyond its domain of validity is inaccurate. The interpretation of old theories may also be incompatible with their successors, but to the extent that different interpretations of a theory give the same predictions, the underlying ontology is not related to scientific results.

As one example, scientists of 17th- to 19th-century Earth considered many phenomena, such as heat and electricity, to be imponderable fluids, similar to material liquids and gases, but lacking mass. We now know this to not be technically true, yet we still talk about things such as heat flux and electric currents, because the analogy still works. In fact, the analogy works well enough that this guide will use it to help classify the myriad different manifestations of matter into an easy-to-think-about scheme.

Energy is a very useful property for describing physical systems. However, for anything interesting to happen, a physical system also needs to have interactions. We can bring these concepts together by considering a potential &phi;, which an energy-possessing object interacts with as long as it possesses a quantity q, such that its energy changes by dE = q d&phi;. In some systems, particularly where the potential is contstant while the quantity changes, it is more useful to instead consider the internal energy of the system changing as dE = &phi; dq.
 * Interactions - potentials and transformations

Meanwhile, another useful relationship between potential and quantity is to consider how much the amount of quantity within a system changes when the potential changes. For the time being, this guide will call this the constitutive ability, which is not an actual scientific term; examples include capacitance for electric charge and potential, heat capacity for entropy and temperature, and elastic modulus for strain and stress. There can also be constitutive abilities relating potentials with unassociated quantities; for example, the piezoelectric coefficient relates electric polarisation to applied mechanical stress.

Finally, one particular type of interaction is a transformation, in which the constitutive abilities of an object are changed. For instance, melting a solid into a liquid will change how it deforms in response to pressure.

As previously mentioned, one relativistic effect is continuity, the property that conserved quantities cannot appear from or disappear to nowhere, or teleport. This makes it reasonable to define a current density, which is the density of the quantity multiplied by its velocity.
 * Dynamics - continuity, waves and solitons

The existence of quantum waves moving through spacetime was also mentioned, but of course, other waves exist too. Roughly speaking, they are the result of a constitutive ability causing a movement of a conserved quantity, and therefore a movement of energy, while a related relativistic effect reacts against this. For example, the speed of sound waves through a material depends on the substance's bulk modulus, as well as its mass density. The higher the former and the lower the latter, the faster the waves travel, but the latter is still necessary for there to be any waves at all. One important type of wave, which deserves to be distinguised from regular propagating oscillations, is the soliton.

Once we've defined something that can move such as a wave or soliton, made sure that it obeys continuity, and figured out how to change its energy using a potential, we finally need to describe its movement. Two things can cause a current to flow: a potential that changes over a distance, causing objects to increase in energy as they move down the potential (conduction), and random motion of the objects that make up the current, causing a statistical tendency for them to spread out evenly (diffusion).
 * Transport phenomena - diffusion and conduction

Conduction is only limited by properties of the material that the current is moving through: a potential gradient would normally cause the velocity - and therefore current - to continually increase, and then stay at a constant speed when the potential is constant, but when the material has resistance (i.e. is not a "superconductor"), this limits the acceleration to result in a constant current, and causes the velocity to slow down to zero (relative to the material) when the potential is constant.

The List
This is the list of what I call here "matter manifestations", or the general categories of physical phenomena: from elementary to emergent, and from conventional to theoretical.

 »»»= Particle=

Material=

The material scale forms as a result of bound states: where the mutual attraction between particles binds them into larger composite structures. Plasma results instead when attraction holds the particles together, but they have too much kinetic energy to remain bound.
 * Chromodynamic bound states are nuclei, usually composed of protons and neutrons, while chromodynamic plasma is quark-gluon plasma.
 * Electrodynamic bound states are atoms (nuclei bound to electrically-charged particles) and onia (electrically-charged particle-antiparticle pairs, which quickly annihilate), which can in turn bond together to form chemical substances; electrodynamic plasma is ionic plasma.
 * In geometrodynamics, usually only large congegrations of atoms can form bound states, forming astronomical objects. However, when the gravitational field is sufficiently great, black holes form, and atom-like holeum can result. Gravitational plasma must be composed of uncharged dark matter.

Matter has three properties that can act as the mutable quantities caused, and acted upon, by a potential: polarisation, entropy, and deformation. On microscopic levels, waves of these properties exist as quanta, known as quasiparticles, which can themselves form bound states and plasmas.
 * Material properties

A phase transition is when the constitutive abilities of a material are changed by the breaking and/or making of bonds within or between bound states. When a bound state itself is transformed, it is known as a reaction. For example, a nuclear reaction transforms one nucleus into another (by the release, capture or decay of nucleons), and a chemical reaction transforms one chemical substance into another (by the release, capture, decay or sharing of orbital charges).

Polarisation is a measure of microscopic order, induced by external fields that are derived from the elementary potentials. It is the alignment of electric dipoles, which are bound states that are arranged so that the opposite charges are spatially separated, or magnetic dipoles, which are caused by charged particles with angular momentum that thereby act like bound magnetic charges. The associated constitutive abilities are the electric and magnetic susceptibilities.
 * Paraelectic and paramagnetic materials have positive susceptibility, and polarise in such a way as to reinforce external fields, while dielectric and diamagnetic materials have negative susceptibility, and polarise in such a way as to reduce external fields. Ferroelectric and ferromagnetic materials, which may be polarised even without an external field, have effectively infinite susceptibility.
 * Superconductors expel magnetic fields during their creation, and therefore have a magnetic susceptibility of -1. The equivalent "superresistor" (not to be confused with a simple insulator), which completely inhibits electric fields, would require magnetic monopoles to create a direct analog of a superconductor.
 * The non-existence of negative energy means that gravity can only create gravitomagnetic dipoles, while colour confinement means that the issue of chromoelectric and chromomagnetic polarisation are irrelevant (although QCD matter can be colour superconductive). In electrodynamics, both electric and magnetic polarisation come into play, and there is another noteworthy effect: the speed of light waves passing through materials is altered in a wavelength-dependent way by susceptibilities.

Entropy is a measure of microscopic disorder, resulting from statistical mechanics and the internal energy of the material (roughly, temperature), and deformation is a measure of macroscopic change, caused by applied forces (stress). Both are related, as energy is conducted through materials through mechanical vibrations; microscopically as heat and macroscopically as sound. The associated constitutive abilities are the elastic moduli, relating stress to deformation; heat capacity, relating temperature to entropy, and thermal expansivity, which is both the relationship between temperature and deformation and the (negative reciprocal of the) relationship between stress and entropy.
 * Elasticity is when a material deforms reversibly, plasticity is when it deforms irreversibly (ductility under tensile stress; malleability under compressive stress), and brittleness is when it fractures. Increasing stress causes materials to pass through each of these stages successively.
 * Hardness and strength are the ability to withstand large stresses before deforming plastically and fracturing respectively, while resilience and toughness are the equivalents for absorbing energy. Stiffness (for solids) and viscosity (for fluids) are overall resistance to deformation.

There are other constitutive abilities relating temperature and stress to polarisation, and the derived fields to entropy and deformation. These have technological applications, but are not worth discussing here.


 * States of matter

Communal= The communal scale is the scale on which the underlying physics is no longer directly relevant; changes in systems are based on computation. Physical forces are replaced with more abstract concepts as potentials, while organisational patterns are the currents that flow. There are far too many examples to list here, but life is the field in which the communal scale most commonly applies: organisms are repelled by scarcity and danger, and are subjected to social stressors and pressures when part of a community. Rather than chemical reactions and phase transitions, the transformations that species and societies undergo are evolution and revolutions.

It is worth noting that many supernatural beliefs appear to have their origin in misinterpreting abstract, emergent phenomena that are active on the communal scale as being just as much part of the laws of physics as any mechanical forces. This is not to say that supernatural beliefs have no other sources (experiences during altered states of consciousness come to mind), but there are numerous examples of this that can be taken from human culture alone.

Hypothetical= Collectively, unconfirmed ideas in fundamental theoretical physics are known as physics beyond the Standard Model; they are created in an attempt to solve problems in the Standard Model of particle physics. They fall into three main categories:
 * Sympathetic magic, based on the rule of "like affects like", can involve many such abstractions, such as finding a natural object or crafting an image representing fertility and placing it in a barren field in the hopes that the fertility will diffuse out and help food plants grow.
 * Prescientific alchemy (from the literal, not allegorical, viewpoint) was similarly filled with these ideas. The classical elements were based on properties of matter. The hypothetical Philsopher's Stone removed impurity from base metals to make gold, and was therefore associated with the (similarly-hypothetical) Elixir of Life, which removed the impurity of mortality from humans.
 * Magical rituals, from simple spells to elaborate ceremonies, can come from assuming that social rituals, used to maintain hierarchies in the social species that humans are, are just as capable of establishing hierarchies over nature with magicians at the top.
 * The teleological assumption that "everything must have a purpose", used to justify the existence of spiritual beings such as supernatural creator deities, is based around the idea that conscious intent is an integral part of the universe. Beliefs about psychic powers arguably come from the same source. The ideas of spirits and rituals are closely connected: ritual magic can consciously come from assuming that there exist spirits who respond to rituals, or the existence of spirits can be used as post hoc rationalisation for ritual behaviour.


 * Grand Unified Theories, or GUTs, attempt to directly unify the electromagnetic and nuclear forces.
 * Supersymmetry, or SUSY, is the idea that all fundamental particles have their own "superpartner". A particle and its equivalent "sparticle" are identical except for their spin, and that the latter has a greater mass. The only stable sparticle matter is predicted to be dark.
 * Gravitational theories: Our current picture of gravity, general relativity, is a classical field theory rather than a quantum one, and can conflict with the Standard Model of particle physics where the two theories meet. A related issue is that of unexplained phenomena in physical cosmology.

Most of the ideas that result from beyond-the-Standard-Model physics are of little technological use: for the most part, any particles that we have not yet discovered must either be too heavy and unstable for us to have created and detected already, requiring a lot of energy to produce and decaying rapidly into other particles, or interact too weakly with known particles to have much of an effect on them. Still, there are many features of these theories that could still be of practical value.


 * Extra dimensions

Extra dimensions would have to be finite and microscopic in size for us to not be aware of them.

Sufficiently high-energy particles may form standing waves along these dimensions. This traps kinetic energy as mass, causing the particles to appear to be more massive than their equivalents that remain in 3+1-dimensional spacetime. The idea of using these "Kaluza–Klein particles" for energy is that the kinetic energy of their decay products returning to 3-dimensional space could be harnessed.

Some models of discrete extra dimensions allow fermions to oscillate between branes to achieve faster-than-light travel, while Gauss–Bonnet gravity makes it possible for wormholes to exist even without matter.


 * Negative energy

Negative-energy "exotic matter", particularly phantom energy, could be highly useful in metric engineering.

Negative masses would allow for the formation of gravitational dipoles. This could be used for shielding against gravitational fields, much like how a faraday cage shields against electric fields, one proposed example being a component of an artificial gravitational field that is fully contained inside a spacecraft. Negative mass would still be attracted to positive mass, rendering "anti-gravity" by this method impossible. However, as negative mass has a negative gravitational field and will therefore constantly repel a positive mass, a dipole arrangement can be used to make a reactionless space drive known as the diametric drive. If the two masses are equal in magnitude, the negative one will gain exactly the right negative momentum and kinetic energy to cancel out the positive momentum and energy gained by the positive mass.

Furthermore, negative mass is particularly required for time travel (and, due to relativity of simultaneity, faster-than-light travel) in standard general relativity. The most definite way of achieving this is via paths of warped spacetime: the krasnikov tube, the wormhole, and the pure time-machine tipler cylinder. The former two could be made into time machines by exposing one end to time dilation so that the event of a spaceship exiting that end is in the past light cone of the same spaceship entering the other end (in the case of krasnikov tubes, this necessarily requires multiple tunnels). Wormholes, although not krasnikov tubes or tipler cylinders, have other applications:


 * They can be collapsed in such a way as to cause a destructive release of energy, either by the release of their positive mass-energy, or by the sudden release of large amounts of negative energy in order to create a rapid expansion of spacetime in a target volume of space that ultimately tears apart any matter inside.
 * Basement, baby or sometimes "pocket" universes are regions of spacetime that are seperated from the rest of the universe, except perhaps for a wormhole connection. Basement universes could be used for high-energy computation, engineering, or experiments that involve carefully controlled conditions without outside interference, or simply increasing the amount of space available for a particular purpose by making a structure that is bigger on the inside than on the outside. A military application would be encasing a target within a basement universe and then destroying it, taking out the target in the process. Another suggestion is the usage of non-orientable wormholes to hide objects as dark matter; in this case, the wormhole connects to a "mirror" region of our own universe rather than to a smaller basement one.

A more complex space drive is the alcubierre drive, or warp drive. It appears to be the case that an alcubierre drive could allow for faster-than-light travel, however, there are likely to be issues with the stability of the warp bubble at such speeds. Warp bubbles could also function as basement universes, as they are both bigger on the inside and seperated from the rest of the universe.


 * Scalar gravitational field

In scalar-tensor theories of gravitation, and quantum theories with dilatons (often associated with extra dimensions), the gravitational constant can vary, allowing for the bias drive class of space drive to exist.


 * Topological solitons

Topological defects, comparable to the cooling of crystals from a liquid, may be able to form within the Higgs field. There are two main types of topological defects with technological applications.

Cosmic strings are one-dimensional topological solitons, and under sufficient tension to give them an incredibly high mass. Looped cosmic strings also have large amounts of stored potential energy; this would usually cause them to decay via gravitional radiation, but they could instead be stabilised as vortons, either for later use as an energy source or for artificial gravity and inertia damping.

Magnetic monopoles are particles with magnetic charge (i.e. either a north pole or a south pole, but not both), and can otherwise be described as zero-dimensional (point-like) topological defects.

Many Grand Unified Theories predict the existence of interactions that violate baryon number and lepton number, but keep the difference between the two numbers constant, the effect being that proton decay would occur via X and Y bosons and could be used as a source of energy. Although these bosons would be much heavier than any Standard Model particles, making proton decay rare at reasonable temperatures, their existence in the unbroken GUT-symmetry within monopole cores could be used to catalyse proton decay, only requiring high energies for initial monopole production.

If different non-annihilating types of stable monopoles exist, then the greater mass of monopoles than other particles, and the greater strength of magnetic than electric forces, would make materials that are denser and stronger than atomic matter possible; applications therefore include metric engineering (particularly artificial gravity, inertia damping, and gravitomagnetism), armour, astroengineering, and picomachines.

Applied Technology
Once you are in possession of some kind of technology, it helps to have something to use it for.

 »»»= Applications=

Most applications of technology can be abstracted into an industrial process, in which some kind of "substance" - material or not - is the target of the process. This process can be applied to technologies including computation (where the "substance" is information), biotechnology (where food or medicine may be the desired end product, or it may be the starting material used by the "technology" that is a living organism), to manufacturing (where raw materials are transformed into some kind of utility).
 * Acquisition is the stage in which the originating "substance" is gathered: agriculture, mining, solar power collectors and sensory devices are all means of doing this.
 * Processing is the transformation of the originating "substance" into a desired end product, whether this is by chemical or mechanical reactions for material products, or by mathematical algorithms in information technology.
 * Transfer/storage is how any "substance" - fully, partially, or not-at-all processed - is made to go to where it is needed, or kept from inconveniently disappearing.
 * Repair/upgrade is further processing done to bring a product either up to a standard from which it has fallen, or up to a new standard. In the example of biotechnology, medicine can be considered repair, while technological augmentations can be considered an upgrade (when not used merely to replace natural capabilities that have been lost).

Another useful categorisation is based on how technology is used to affect the momentum and internal energy (or, usually equivalently, temperature) of a target.
 * Power sources increase the internal energy, while cryogenics decreases it. Due to a side-effect of statistics known as the second law of thermodynamics, cryogenics itself requires a power source.
 * Propulsion increases the momentum of a target in a particular direction, or alternatively, decreases it in the opposite direction.
 * Shielding and damping decrease the momentum. Shields act to protect objects from outside forces, while dampers act to protect them from their own acceleration.

Note that all of the aforementioned applications of technology can be weaponised with a little bit of creativity. For example, some chemical weapons process a functioning metabolism into a non-functioning one, while kinetic weapons transfer enough energy and momentum into a target to tear it into non-functioning pieces.

Other applications exist to satisfy psychological needs but otherwise have no practical purpose; in other words, they would be of no use to emotionless robots. These needs include aesthetic needs (where the technology is known as "art"), entertainment (of its many varying kinds, including some forms of art), and religion (including religious art). Classes of Advancement= A common pastime in speculative xenology is classifying technological civilisations by their level of technological advancement. The most popular means to do so is the Kardashev scale, in which civilisations are assigned a tier based on their power usage: Type I for controlling the power output of a planet, Tier II for controlling the power output of a star, Type III for controlling the power output of an entire galaxy, etc.

This can be extended as a logarithmic scale to cover tiers that are not natural numbers, such as Type 0 for controlling a megawatt of power, or Type 0.7 for late 20th-/early 21st-century humanity. The applicability of the Kardashev scale is debatable, especially from Type II onwards, as it implicitly assumes that the technological development of a society is directly correlated with number of dyson spheres that it has in use.

Of course, civilisations need not fit along an idealised correlation between technology and size. Departure from such a scheme can happen either naturally (such as "swarm" species that choose to focus on rapid expansion and are thus far larger than might be expected, perhaps being Karashev II from sheer bulk of planets), as a result of internal or external influences causing a loss of either extent or technology, or due to the (accidental or intentional) influence of more advanced societies gifting them with high technology or transplanting them across space.

Here is a modified version of the scale, intended to be less flawed. Instead of using Kardashev tiers based on actual power consumption, societies are assigned to classes based on how much power their highest technology could access if they chose to put it to that use, based on transitional "revolutions" in which the higher-energy technology is developed.

Initially, species are non-technological, or use only very simple tools. This includes Stone Age humans, and other intelligent species on Earth such as dolphins, elephants, and non-human primates.
 * Demographic Revolution

During the demographic revolution, societies undergo a demographic transition in which division of labour allows the formation of a class of people who have enough free time to, and can profit from, applying their own creativity to invent new technologies. Earth's example of this was the Neolithic Revolution, in which agriculture and cities first appeared.

Afterwards, we end up with societies such as the civilisations of Earth's ancient and medieval history.

When societies undergo a scientific revolution, their knowledge of the workings of nature - and by extension their ability to manipulate those workings for their own ends - can rapidly increase. This is the stage where we currently are on Earth, and it is associated with smaller revolutions such as the progress of industrial and digital technology.
 * Scientific Revolution

Beyond this point, development becomes speculative, but Class 3 will presumably end with the acquisition of interstellar capabilities, and typically Type I abilities on the Kardashev scale. Most science fiction involves civilisations either in this stage, or later on in the scientific revolution than Earth (as of the time of writing).

Developing more powerful technology that makes use of high-energy physics requires, as one might expect, resources and energy, so the next stage in development is one in which societies have the ability to build megastructures and perform feats of astroengineering. While requring lots of time and materials to create, this would be a highly effective means of obtaining more energy and resources directly from stars, and with that along with millennia of scientific research at their disposal, mastery of all currently-known matter manifestations - and, if physics allows it, many that are not yet known - should surely follow.
 * Megastructural Revolution

Ideas that would currently be viewed as "playing god" - programming artificial intelligences, sculpting life at a whim, even building planets - should be perfectly simple things for civilisations that have undergone a megastructural revolution; they will have achieved far more advanced things in their time.

Whether the actual construction of megastructures is actually the best way of reaching this degree of technological ability is not certain; some might argue that our non-observation of any signs of large-scale galactic engineering in the nearby universe is evidence against it, but see the section on the Fermi Paradox later on in this guide.

Science fiction often speculates about technologies that are not presently known to be possible, and proposes that they are the reserve of civilisations that are advanced beyond the capabilities of Kardashev Type II societies.
 * Beyond?

One common theme is technology that goes beyond our current understanding of spacetime, with applications including time manipulation, basement universes, and of course, more powerful sources of energy leading up to Kardashev Type III levels of energy production. Another theme is the ability to manipulate what we currently know to be the laws of physics by accessing deeper "meta-laws", up to the extent of shaping reality itself to one's own will.

Of course, not only is it not known whether or not these technologies are possible, it's also not known when or how these technologies might even be discovered. Perhaps even these limits will be reached when the stars themselves are harnessed?

Alien Life
Along with advanced technology, one of the most important features of science fiction is the aliens.

Exobiology
What are aliens made of and what do they breathe? What do they look like? What are their minds like? And where in the universe are they?

 »»»= Biochemistry=

[initial description of what is required]

[narrowing down the elements]

Further details ultimately result in there being countless different biochemistries, differing in the choice of minor elements (phosphorus or arsenic; sulfur or selenium), the chirality of molecules, and how those molecules are arranged into complex molecular machinery. So, in order to classify the main bases of life, this guide will consider the main features of metabolisms that can sustain large, complex organisms.


 * Molecular - carbon and silicon


 * Ionic - metals and plasma


 * Scarce and artificial

Intelligence=

There are a few things to consider when it comes to alien minds; namely, how their brains work in a computational sense.

The sentience quotient (SQ) is the efficiency of a brain or computer at processing information. This is not necessarily correlated with intelligence, but it is related to overall processing power in that bigger brains can process more quickly (as a general rule; limiting factors include energy supply and signal speed). SQ is a logarithmic scale (so an increase of one point corresponds to a ten-fold difference in efficiency) with the maximum value, +50, given by the quantum-mechanical Bremermann's limit. Real processing systems cannot dedicate all of their mass to computation, and are therefore very limited by comparison.

To take examples from Earth's species, plants (using hormonal sentience) have SQs from around -2 to +1, with carnivorous plants being at the upper end of that scale. Animals with central nervous systems (i.e. using neuronal sentience) have SQs from around +10 to +13, with the latter value being that which humans have. The limits of nutrient supply prevent biological brains from becoming more efficient than this.

Instead, higher SQs require higher technology. The SQs of electronic computers (and cyborgs with both biological and electronic components) can range from below that of animals, to far beyond human capabilities up to the most advanced superconductor quantum computers with an SQ of +23. Astrophysical phenomena such as degenerate stars can make for even more efficient computronium, with a perfect black hole brain potentially achieving +50. Much like how humans cannot achieve meaningful communication with plants, discourse between humans and these higher sentiences may be similarly limited, at least from the perspective of the latter.

Xenopsychology makes up the remainder of the differences between alien minds. These are shaped by evolution (or creation, in species whose development has been manipulated artificially), and the possibilities may well be limitless. Instead, it is best to deal with this subject by considering places where human and non-human mentalities might differ, and also where they may be similar, depending on how they evolved. One aspect to consider is social structure: for example, species that evolved from swarms instead of primate-like hierarchies might lack such emotions such as desire for personal power, and behaviours such as social rituals (perhaps even including simple things, such as greetings).

Similarly, any psychological, behavioural and cultural features could be shared between humans and other sapients. However, the only universally-shared features are likely to be those that are necessary for a species to be how it is, such as survival- and reproduction-related instincts amongst mobile organisms that are capable of acting on instincts, and social coordination and an understanding of mathematics in any species that has managed to develop advanced technology. While a mind's psychology should be limited to making sense in the context of its origins, other than those shared features, anything can happen.

External anatomies= What could aliens look like? While Earth-centric terms such as "humanoid", "reptilian", "insectoid" and so on are common, here's a more rigorous system.

The overall shape of an organism can be defined with three features.
 * Body plan

Symmetry, either:
 * Bilateral (symmetry across a plane, with left-right, front-back and top-bottom divisions; like most animals on Earth),
 * Radial (symmetry around a line, with only top and bottom surfaces; like jellyfish),
 * Polyhedral or spherical (symmetry around a point; like bizarre sentient basketballs), or
 * Asymmetrical (like plants and sponges)

Elongation, from serpentine, to elongate, to round, to flat (this is obviously redundant for spherically-symmetric organisms, which are by definition round). If no two dimensions are similar in size, that puts the organism in a seperate category. Finally, an amorphous organism has no set elongation.

Orientation, with the axis of elongation pointing forwards (x-orientation), sidewards (y-orientation), or vertically (z-orientation). Some organisms may have multiple components with different elongations and/or orientations; for example, centauroid creatures may have an x-orientated elongate abdomen with a z-oriented elongate thorax pointing upwards from the front.

Organisms that don't move are described as sessile; if they're not completely incapabe of movement, they might be planktonic organisms that drift around with sails, parachutes, or hydrogen balloons.
 * Locomotion

Many animal-like organisms, such as animals, have legs. They can then be bipedal, tripedal, quadripedal, hexapedal, or generally x-pedal. Others move without specialised limbs, and so are nullipedal.

Rotal organisms use wheels, or similar devices. They're most likely to evolve where there are large flat plains, maybe gentle rolling hills, and not rough terrain. Foiled organisms use hydrofoils (such as fins, flippers, or oars) or aerofoils (like wings). Propulsive organisms use reaction engines, usually jets.

The covering of an organism's body can be plain, with little more than skin, or covered with mucus, fibres such as fur or feathers, or scales. If this isn't enough, they can sport an exoskeleton, or even a full shell.
 * Integument

Often this is where the traditional Earth-centric creature categories come in: for example, humanoids (bilateral, elongate, z-orientated, and usually bipedal creatures) are known as "amphbian" when they have a slimy coating, "mammalian" when they're furry, "avian" when they're feathered, "reptilian" when they have scales, and "insectoid" when they have an exoskeleton. Fermi Paradox and Drake-ish Equations=

[description of Fermi paradox]

[initial description of Drake-ish equation; exclusion of starlife, jovian life, and microbes]
 * Scarcity of species

[galactic habitable zone]

[low-variability, ~G-class, non-disruptive-multiple stars]

[right size and composition of planet]

[orbital considerations]

[actual evolution of life and intelligence]


 * Stagnation


 * Setbacks


 * Avoidance

Exopolitics
There are four main areas by which societies - alien and otherwise - can be classified: the leadership, the centralisation of authority, the freedom given to citizens, and the form of economy. For the most part, these exist along a spectrum, and therefore the difference between the categories is often vague at best.

 »»»= Leadership= We'll call this the standard scale of government. It ranges from a single individual having control to the entire population having a say in the running of civilisation.
 * Standard Scale


 * Autocracies and monarchies (rule by one) are controlled by an individual. A monarch tends to be a specifically hereditary position.
 * Diarchies and polyarchies (rule by two and rule by many) can sometimes be seen as intermediate between monarchy and oligarchy, but usually even polyarchies have sufficiently few rulers (less than ten) so that they work in effectively the same manner as autocracies.
 * Oligarchies (rule by few) are controlled by a large number of individuals relative to the size of average social groups, but only a small proportion of the total population.
 * Democracies (rule by the people) are controlled by a significant proporion to a large majority of the population, not to be confused with systems where the government is merely elected democratically.
 * Anarchies or isocracies (rule by none and rule by all) exist when political hierarchies are unneccessary (as some species simply lack social hierarchies), rejected (for some ideal, from anti-establishment to social darwinist), or destroyed due to civil strife.

Note that the difference between these categories often depends on the natural social systems of the species involved, as well as the size of the civilisation itself. For example, a government consisting of hundreds of individuals may be a democracy for a small tribal society, or one in which social bonding is rare, while it may be an oligarchy for a galaxy-spanning empire, or a polyarchy for a species in which social interactions normally involve handling large numbers of interpersonal relationships.

Another factor within standard scale governments is the legitimacy by which leaders claim their rule.


 * Electoral systems, where the leaders are chosen by the general populace.
 * Dicatorships, where a particular group is given privilege to rule. There are countless possibilities as to which may be used in a civilisation, with popular ones including age or gender, divine commandment, merit of personality, military power, perceived intrinsic superiority, or wealth.
 * Cryptocracies, in which the real leaders of the society are kept secret from all but very few individuals, and there is often a puppet government put into place to hide the existence of cryptocracy.

Further means of categorisation can also be used, such as the length of time that a leader can be in power for, variously from short terms to being able to rule for life.

Note that combinations of governments can also exist within the same society. For example, constitutional monarchies usually implement the concept of trias politica (seperation of powers), and have a hereditary monarch as the (symbolic) head of the executive branch, while a form of electoral system such as a representative democracy or democratic republic holds most or all of the real power.


 * Collective consciousness

A collective consciousness is a system by which all members of a society are capable of directly sharing thoughts, emotions, opinions, and other concepts, directly to each others' brains. This can be achieved by various means, such as pheromones or brain implants. Collective consciousnesses often have aspects of isocracies, democracies, or even autocracies, although in practice the decisions are all made by the shared mind and not by individuals acting either alone or in consensus. The types of collective consciousness make up three of the four elements of a system of two variables: whether a society is neurologically unified, and whether it maintains individuality. Standard scale societies exist when the former does not hold and the latter does.


 * In a hive mind, there is no individuality; all entities within the consciousness are merely different bodies which the same mind has complete control over.
 * In a group mind, all beings have individuality, but are all still mentally connected. These can resemble standard scale govenments, since there is usually a greater need for a system of organisation and administration in a society with many individuals than one without.
 * In a typical superorganism, a central mind (often referred to as a "king" or "queen", due to the superorganism's similarity to an autocratic monarchy) exerts its will, via pheromones or a similar one-way means of control, on other beings that exist purely to serve the superorganism. Such creatures are usually divided into castes such "workers" and "soldiers", and are created purely for specific tasks. The central mind often receives information from outside via its subservient beings, but it is far from the clear two-way flow of information that group and hive minds have.

Entities in hive minds and superorganisms may be incapable of normal functioning as individuals, and if they are separated from their collective consciousness then they may revert to basic instincts or cease to function entirely (either becoming vegetative or even dying).

Everything else= The centralisation of a society relates to where most of its organisation occurs.
 * Centralisation


 * Unitary societies are the most centralised, with all decisions falling to a central authority.
 * Imperial societies often evolve from unitary governments. They have a powerful central authority, but also have seperate systems for controlling the other regions within their dominion.
 * Hegemonies, federations and confederations are less centralised than empires, with individual regions having increasing degrees of autonomy.
 * Alliances rarely count as distinct civilisations, instead being groups of completely independent nations joined by an agreement such as a military pact. Such groups are not listed here; however, the memeber states of some alliances are closely associated enough for them to be indistinguishable from a single nation, and these may be listed here.
 * Decentralised societies are ones where there is no central form of government. It is almost impossible outside of a democracy or isocracy.

The freedom experienced by citizens of a society is only relevent to societies governed by standard scale systems; hive minds and superorganisms and can simultaneously be viewed as being perfectly libertarian and totalitarian due to the nature of collective consciousness.
 * Freedom


 * Libertarian societies grant numerous social, political, and economic rights to all of their citizens.
 * Egalitarian societies treat all citizens equally, but not necessarily with fully libertarian rights.
 * Authoritarian societies involve obedience to authority by their citizens.
 * Totalitarian societies involve total control of citizens by authority, often resembling an attempt at creating a hive mind but with coercive rather than biological means of control. Fascist societies control by ideologies, such as the nation or race being more important than the individual, while police states condition very strict rules over society. In surveillance societies, the government uses mass surveillance, usually using infotech, sometimes invading privacy and destroying civil liberties to do so, in order to maintain social control.

Economies are, essentially, systems of distributing limited resources. The main scale for economic systems is the capitalist-socialist spectrum, where capitalism is the range of systems in which the means of production are privately owned, and are operated for a profit involving the acquisition of currency (usually in the form of money).
 * Economy


 * Liberal societies involve little state control over the economy, and usually there are laws in place to encourage free trade and prevent corporatism or mercantilism.
 * Mercantile societies have increasing control by the government, often with the ideal of the interests of the state being a greater priority than that of the individual. They may focus heavily on international trade, with a significant proportion of the population working in production and manufacturing so that there is a large excess of goods that can then be exported to other states for large financial gains, with few financial losses as a result of imports. Often, high taxes are then used to transfer this money to the government.
 * Corporate societies have a large degree of control is exerted over the economy, either by the state or by large corporations. In societies ruled by totalitarian and corrupt regimes, corporatism is often used for the benefit of the ruling party. Business-controlled corporatism is clearly capitalism, while state-controlled corporatism often has socialist features.
 * Welfare or mixed societies are those which have aspects of both capitalist and socialist aspects. In practice, most economies are mixed, but with a tendency towards one end of the capitalist-socialist spectrum, such as being mostly capitalist but having nationalised institutions such as publically-funded healthcare or a limited system of redistributing wealth, or being mostly socialist but with a limited trade-based economy.
 * Socialist societies are those in which the means of production are owned and controlled by the public, often by the state on the behalf of its citizens.
 * Communist societies are where a socialist economy has become universal; resources are taken from all workers and (ideally) distributed to each citizen of the society according to their needs.

Non-economic societies also exist, which are those that require little to no labour for the acquisition of essential products such as food, water, and shelter. Despite the names, there can still be scarcity in these societies, either from natural disasters or intrinstically limited commodities.


 * Pre-scarcity societies are where the economy has not developed. Economies normally evolve with the emergence of the division of labour within societies, such as when only certain people are in control of food production via farming; pre-scarcity societies use only food that is naturally occuring instead. Similarly, since the division of labour is usually necessarily for increasing technological development, pre-scarcity societies are most commonly represented by stone age tribes. Alternatively, the collapse of civilisation, such as that resulting from internal conflict, can result in an economic collapse that leads to many individuals being forced to adapt to a pre-scarcity style of life.
 * Post-scarcity societies are usually those which previously had an economy - hence the name - but due to advanced technology (such as automation, high-efficiency clean energy generation, and matter replicators), managed to remove the need for a system of distributing limited resources, as resources were no longer limited.