Physical cosmology

Physical cosmology is the study of the largest-scale structures and dynamics of the Universe and is concerned with fundamental questions about its origin, structure, evolution, and ultimate fate. For most of human history, it was a branch of metaphysics and religion. Cosmology as a science originated with the Copernican principle, which implies that celestial bodies obey identical physical laws to those on Earth, and Newtonian mechanics, which first allowed us to understand those physical laws.

Physical cosmology, as it is now understood, began with the development in 1915 of Albert Einstein's general theory of relativity, followed by major observational discoveries in the 1920s: first, Edwin Hubble discovered that the universe contains a huge number of external galaxies beyond our own Milky Way; then, work by Vesto Slipher and others showed that the universe is expanding. These advances made it possible to speculate about the origin of the universe, and allowed the establishment of the Big Bang Theory, by Georges Lemaitre, as the leading cosmological model. A few researchers still advocate a handful of alternative cosmologies; however, most cosmologists agree that the Big Bang theory explains the observations better.

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Big Bang

The Big Bang theory is the prevailing cosmological model for the universe from the earliest known periods through its subsequent large-scale evolution. The model accounts for the fact that the universe expanded from a very high density and high temperature state, and offers a comprehensive explanation for a broad range of phenomena, including the abundance of light elements, the cosmic microwave background, large scale structure and Hubble's Law. If the known laws of physics are extrapolated beyond where they are valid, there is a singularity. Modern measurements place this moment at approximately 13.8 billion years ago, which is thus considered the age of the universe. After the initial expansion, the universe cooled sufficiently to allow the formation of subatomic particles, and later simple atoms. Giant clouds of these primordial elements later coalesced through gravity to form stars and galaxies.

Physical

Physical may refer to:

Absolute (philosophy)

In religious philosophy, the Absolute is the concept of (a form of) Being which transcends limited, conditional, everyday existence. The manifestation of the Absolute has been described as the Logos, Word, the Ṛta or Ratio (Latin for "reason").

Related concepts are the Source, Fountain or Well, the Centre, the Monad or One, the All or Whole, the Origin (Arche) or Principle or Primordial Cause, the Sacred or Holy or Utterly Other (Otto), the Form of the Good (Plato), the Mystery, Nirvana, the Ultimate, the Ground or Urground ("Original Ground").

It is sometimes used as an alternate term for the more commonly used God of the Universe, the Divine or the Supreme Being ("Utmost Being"), especially, but by no means exclusively, to express it in less personal and more impersonal representations. The concept of the Absolute may or may not (depending on one's specific doctrine) possess discrete will, intelligence, awareness, or a personal nature. It is sometimes conceived of as the source through which all being emanates. It contrasts with finite things, considered individually, and known collectively as the relative. This is reflected in the name's Latin etymology absolūtus which means "loosened from" or "unattached" (from a subject-object dualism).