Cosmology

:For the jazz band, see Cosmology (band).

Physical cosmology

Physical cosmology is the branch of physics and astrophysics, which deals with the study of the physical origins of the universe and the nature of the universe on its very largest scales. In its earliest form it was what is now known as celestial mechanics, the study of the heavens. The Greek philosophers Aristarchus, Aristotle and Ptolemy proposed different cosmological theories. In particular, the geocentric Ptolemaic system was the accepted theory to explain the motion of the heavens until Nicolaus Copernicus, and subsequently Tycho Brahe, Johannes Kepler and Galileo Galilei proposed a heliocentric system in the 16th century.

Related Topics:
Celestial mechanics - Heavens - Aristarchus - Aristotle - Ptolemy - Geocentric - Ptolemaic system - Nicolaus Copernicus - Tycho Brahe - Johannes Kepler - Galileo Galilei - Heliocentric - 16th century

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With Isaac Newton and the 1687 publication of Principia Mathematica, the problem of the motion of the heavens was finally solved. Newton provided a physical mechanism for Kepler's laws and his law of universal gravitation allowed the anomalies in previous systems, caused by gravitational interaction between the planets, to be resolved. A fundamental difference between Newton's cosmology and those preceding it was the Copernican principle that the bodies on earth obey the same physical laws as all the celestial bodies. This was a crucial philosophical advance in physical cosmology.

Related Topics:
Isaac Newton - Principia Mathematica - Kepler's laws - Law of universal gravitation - Anomalies - Copernican principle - Physical law

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Modern scientific cosmology may be considered to begin in 1915 with Albert Einstein's publication of his theory of general relativity and the growing ability of astronomers to study very distant objects. Prior to this, physicists had assumed that the universe was static and unchanging. However, the general theory of relativity was not amenable to a static universe. Thus the big bang theory was proposed by the Belgian priest Georges LeMaître in 1927 and rapidly confirmed by Edwin Hubble's discovery of the red shift in 1929 and later by the discovery of the cosmic microwave background radiation by Arno Penzias and Robert Woodrow Wilson in 1964.

Related Topics:
Albert Einstein - General relativity - Astronomers - Big bang - Belgian - Georges LeMaître - Edwin Hubble - Red shift - Cosmic microwave background radiation - Arno Penzias - Robert Woodrow Wilson

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