利用者:菊地 英仁/Cosmogony

Cosmogony, or cosmogeny, is any theory concerning the coming into existence or origin of the universe, or about how reality came to be. The word comes from the Greek κοσμογονία (or κοσμογενία), from κόσμος "cosmos, the world", and the root of γί(γ)νομαι / γέγονα "to be born, come about". In the specialized context of space science and astronomy, the term refers to theories of creation of (and study of) the Solar System.

Attempts to create a naturalistic cosmogony are subject to two separate limitations. One is based in the philosophy of science and the epistemological constraints of science itself, especially with regards to whether scientific inquiry can ask questions of "why" the universe exists. Another more pragmatic problem is that there is no physical model that can explain the earliest moments of the universe's existence (Planck time) because of a lack of a consistent theory of quantum gravity.

Cosmogony compared with cosmology

Cosmology is the study of the structure and changes in the present universe, while the scientific field of cosmogony is concerned with the origin of the universe. Observations about our present universe may not only allow predictions to be made about the future, but they also provide clues to events that happened long ago when...the cosmos began. So—the work of cosmologists and cosmogonists overlaps. — National Aeronautics and Space Administration (NASA)

Cosmogony can be distinguished from cosmology which studies the universe at large and throughout its existence, and which technically does not inquire directly into the source of its origins. There is some ambiguity between the two terms; for example, the cosmological argument from theology regarding the existence of God is technically an appeal to cosmogonical rather than cosmological ideas. In practice, there is a scientific distinction between cosmological and cosmogonical ideas. Physical cosmology is the science that attempts to explain all observations relevant to the development and characteristics of the universe as a whole. Questions regarding why the universe behaves in such a way have been described by physicists and cosmologists as being extra-scientific, though speculations are made from a variety of perspectives that include extrapolation of scientific theories to untested regimes and philosophical or religious ideas.

神話上の宇宙進化論

Also of interest are supernatural creation accounts(creation myth = 創造神話), as in ancient(古代の) Greek myth (see below) or in the Creationism(創造論) of the Abrahamic religions(アブラハムの宗教).

ギリシャ神話は実在（リアリティー）を総括して表現したいという欲求を具体化した。そしてこの一般化による刺激は推論的な理論化の最初のプロジェクトの基礎となった。

Greek mythology(神話) embodied(embody = 具体的に表現する、具体化する、組織化、体系化する) the desire(欲望、欲求) to articulate(発音[言語]の明晰な、思想を表現できる，表現する) reality(現実、実在) as a whole(as a whole = 総括して、全体として) and this universalizing(universalize = 一般化する、普遍化する) impulse(衝撃、推進力、刺激) was fundamental(基本の、基礎の、根本的な、主要な) for the first projects(計画、事業、プロジェクト) of speculative(思索的な、推論的な) theorizing.(theorize = 理論付ける、理論化する)

It appears that the order of 'being(存在)' was first imaginatively visualized before it was abstractly thought.

ヘーシオドス（紀元前8-7世紀）の神統記では、宇宙の起源（アルケー）はカオスであるとされている。

In the Theogony(神統記) of Hesiod(ヘーシオドス) (7th-6th century BC) the origin (arche(アルケー)) of the universe is Khaos(カオス), the Goddess(女神) of the upper air from which everything else appeared.

オルペウス教の宇宙進化論においては、不老のクロノスがアイテールとカオスを生み出し、神であるアイテールの中に銀の卵を作り、そこから他の全てのものが出現した。

In the Orphic(オルペウス教) cosmogony the unageing(不老の) Chronos(クロノス) produced Aither(アイテール) and Khaos, and made in divine(神の) Aither a silvery(銀の、銀白色の) egg from which everything else appeared.

これらの考えは近東の宇宙論やヴェーダの宇宙進化論の影響を受けている。

These ideas are influenced by the Near-Eastern cosmological theories and by the Vedic(ヴェーダ, 前1000-500年頃) cosmogony.

後の哲学者たちは、カオスは不確定の本質であり、そこから物質の宇宙が作られたと考えた。現代語においてカオスという語を「混沌」の意味で使うのはここからきている。

The later philosophers(哲学者) considered chaos(カオス) to be the indeterminate(不確定の、不定の) principle(原理、本質) from which the material cosmos was made; it is from this idea that the modern use of the word as meaning "confusion" has developed.

Epistemological limitations to cosmogony

The assumptions of naturalism that underlie the scientific method have led some scientists, especially observationalists, to question whether the ultimate reason or source for the universe to exist can be answered in a scientific fashion. In particular, the principle of sufficient reason seems to indicate that there should be such an explanation, but whether a satisfactory explanation can be obtained through scientific inquiry is debatable. A scientific examination of cosmogony using existing physical models would face many challenges. For example, equations used to develop models of the origin do not in themselves explain how the conditions of the universe that the equations model came to be in the first place.

Theistic explanations for origins indicate one or more supernatural beings as the explanation, though atheist commentators often point to this as an argument from ignorance or a God of the gaps fallacy, and that such an assumption provides no explanation for existence of the deity. Nondual explanations by contrast state that the very question is misleading, since it contains erroneous assumptions of beginnings, endings and the nature of existence itself, and consider the visible universe as phenomenology.

As a result of this, scientific cosmogonies are sometimes supplemented by reference to metaphysical and theistic belief systems. The problem can be summarized as three classical paradoxes. These paradoxes (discussed by both Kierkegaard and Leibniz) are:

1. reconciling a doctrine of causation (similar to the 13th century proof of God posed by Thomas Aquinas);
2. reconciling the conservation law ("something from nothing");
3. reconciling issues of temporal (as in Zeno's paradoxes) and logical regression.

However, some of the metaphysical principles used to formulate these classical paradoxes no longer enjoy an unchallenged status as laws of thought. For instance, quantum mechanics gives an independent motivation to challenge the principle of sufficient reason.

Planck time limitations to cosmogony

Planck time (10⁻⁴³s) is the time it would take a photon traveling at the speed of light to cross a distance equal to the Planck length (1.616252×10⁻³⁵ meters). It has been proposed that this may be the hypothetical "quantum of time", the smallest measurement of time that has any meaning, although in current physics theory time is not quantized.

Although the laws of physics lose experimental support at the Planck time, modern science has sought to clarify the nature of these paradoxes, so far with only limited success. For example, one can apply the current understanding of grand unified theories (GUTs) – both quasi-classical (such as general relativity) and modern (such as quantum gravity, superstring, and M-theories) – to these three primary cosmogonic paradoxes in thought experiments. While these result in some contradictions and lack completeness in a mathematical sense (being based on axioms that are 'merely' self-evident, but not robust under the stresses of radical scepticism) these paradoxes can nonetheless be analyzed rationally using the subatomic applications of quantum cosmology, particularly through the employment of the Schrödinger wave equations.

In each case, where general relativity fails as the curvature of space-time invokes singularities from its equations at t=0, the statistically "grey" nature of quantum cosmology tends to allow a scientific rationale to account for each paradox, and in so doing allows for a scientific perspective on previously theistic terrain. For example, application of quantum "fuzziness" (per the Wheeler-DeWitt application of subatomic position and momentum equations to universal radius and expansion) avoids boundary issues, as developed in the Hartle-Hawking Wave Function.

All such equations are based on differentials, which assume a continuum, where in our universe, affected by the Planck length and other minimum scales, this continuum has only limited meaning, about which philosophy remains in a state of semantic flux.