True Earth

True Earth is the base world for the alternate versions of Earth. It is the world that shares its characteristics with the majority, or at least the plurality, of alternate Earths, the version of Earth that has the least total divergence from the others. while other alternate Earths differ from True Earth in various ways, most of them share its large-scale geography and history, and those that do, for example, possess a historical divergence at one time are still likely to follow at least the broad lines of the rest of its history.

The term "True Earth" refers to a set of conditions and criteria, and not to one specific world; there is not a particular alternate Earth that can be unambiguously singled out as True Earth. Indeed, it is possible that there are numerous alternate Earths that qualify as True Earths, all filling the necessary criteria but differing in small details of the identities of their inhabitants or of local geography. On the other hand, it's also possible that no world actually fits all the criteria of True Earth, that every alternate Earth possesses some quality that violates the criteria (having some hidden system of magic, for instance, or some minor historical divergence), and that "True Earth" exists only as a sort of composite.

The adjective "Euterran" (pronounced /ˈjuːtɛrən/ or /ˈjuːtərən/) refers to things pertaining to True Earth. Euterran animals, for instance, are animals that exist on True Earth. Unless specified otherwise or unless the context clearly indicates the contrary, most references to "Earth" in the Wongery can be presumed to refer to True Earth.

Geography and composition

True Earth is nearly spherical in shape, though not exactly—it's slightly thicker around the equator than through the poles, making it technically an oblate spheroid, not to mention of course the slight irregularities formed by the mountains and other terrain features. About 71% of the Earth's surface is covered by water; the land is traditionally grouped into six or seven continents, depending on whether Europe and Asia, which are part of the same land mass, are considered to be separate continents or part of the single continent Eurasia. (Geographically, there's little reason to consider them separate continents, but they are traditionally so considered in most English-speaking countries, as well as in the nation of China.) The other continents are North and South America, Africa, Antarctica, and Australia. In addition, of course, there are numerous islands scattered throughout the seas, the largest of which, Greenland, is about two-sevenths the size of Australia, the smallest continent.

The Earth is made up of a number of layers; the outer crust that covers the surface is only seventy kilometers thick at its widest. Below the crust is the mantle, a ductile layer almost three thousand kilometers thick, and below that the dense core, the outer part of which is molten liquid and the inner core, at the center of the Earth, compressed solid. The Earth is composed mostly of iron and its compounds, the next most abundant element being oxygen, followed by silicon. However, much of the iron is in the core, and to a lesser degree in the mantle; in the crust silicon compounds predominate.

Because humans breathe oxygen, it is often assumed that oxygen makes up the majority of the Earth's atmosphere, or air. This is not the case; oxygen makes up less than a quarter of the atmosphere by volume. The atmosphere of True Earth is about seventy-eight percent nitrogen, twenty-one percent oxygen, and one percent argon, the remainder (although these percentages seem to add to 100%, they are rounded and actually add to slightly less) composed of carbon dioxide and other trace constituents. A fair amount of water vapor is also suspended in the atmosphere, making up on average about one percent of it by volume (not included in the above percentages). In any case, the atmosphere becomes less dense the farther from the planet's surface, until about six thousand meters above sea level it becomes too thin for humans to breathe.

History

True Earth was formed about four point five four billion years ago by the coalescence of material from the solar nebula. Sometime between about thirty to a hundred million years after the Earth had formed, a foreign body impacted it and knocked out a large chunk of material which went into orbit around it, becoming the Moon. Meanwhile, the Earth cooled and eventually solidified, and water precipitated to form the oceans. The first life probably formed within the first billion years of the Earth's existence, although early life was prokaryotic and unicellular. Probably by about three billion years ago, some of these cells had developed the ability of photosynthesis, perhaps running out of the energy-rich chemicals that had been supporting them until then. In took perhaps another billion years for eukaryotes to develop, and multicellular life did not arise until about a billion years after that. Humans, the first (and thus far only) noetic beings, finally evolved in Africa less than a million years ago—the more specific time depends on what one classifies as "human", but the modern human species, Homo sapiens, arose less than four hundred thousand years ago.

About nine or ten thousand years ago, humans developed agriculture, and within four or five thousand years cities and civilization had developed. The first known civilization was in Mesopotamia, though others in India and in Egypt were not far behind. Many states and empires rose and fell; philosophies and religions were established. Among the civilizations with the most direct and obvious influence on their successors were Rome in Europe, the Gupta Empire in India, and the Han Dynasty in China. In more recent years, much of the less developed parts of the world were conquered and colonized by European empires, including much of Africa and the Americas. These empires eventually largely broke up, though they left many linguistic, cultural, and ethnic traces of their existence. By the turn of the second millennium CE, technology on True Earth had progressed to the point that computers all over the world were connected by the internet, making it possible to rapidly share and gather information on a global scale. Mankind still remained confined to his homeworld, however; a handful of manned expeditions had been made to the Moon, but no humans had ever gone farther than that from the Earth.

Surroundings

True Earth is situated in the universe of Tamamna, in the cosmos of Xi. More specifically, it's situated in a particular version called True Tamamna, or Eutamamna, though this is subject to similar qualifications as the definition of True Earth. In any case, while some alternate Earths may be located in alternate versions of Tamamna, there are also some alternate Earths that exist in entirely different kinds of plane. True Earth is free from any form of magic, including those that fulfill the definition of magic but are called by other names (such as psionics).

Life

A variety of organisms inhabit True Earth, but all belonging to the empire Terranea, and traditionally to one of the six kingdoms of Animalia, Plantae, Fungi, Archaea, Bacteria, and Protista, though recent evidence has suggested that the last of these are not monophyletic and given grounds for dividing Protista into several further kingdoms. The only noetic organism of True Earth is the human, though there are several other species of reasonable intelligence.

The bacteria and archaea were the first of the modern forms of life to evolve, though they may have been preceded by even simpler organisms, or proto-organisms, lacking their cellular structure. Eukaryotic cells may have been formed when one prokaryotic cell entered another, the two entering into a mutualistic relationship—essentially, the ancestors of the mitochondria in modern eukaryotic cells may have started as independent organisms. There is evidence that multicellularity was achieved in two different ways: the ancestors of modern plants became multicellular by separate unicellular organisms joining together colonially, while the ancestors of animals and fungi were formed by the repeated division of single cells. In any case, while fungi were earlier (and in popular culture still often are) considered a type of plant, in fact animals and fungi are more closely related to each other than either is to plants.

Controversy

Many pediologists question the utility of True Earth, and accuse it of being too provincial and biased toward a particular origin. Indeed, there are some pediologists who use other base worlds for alternate Earths, or who repudiate the utility of having a base world in the first place. Still, True Earth remains a widely, though not universally, used concept in the pediological community, especially among those pediologists living on a magical Earth or some compit that connects to it.