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Main » 2013 » September » 22 » What is Cosmology- Charlotte Olympia by Burt Jordaan
11:34 AM What is Cosmology- Charlotte Olympia by Burt Jordaan |
What is Cosmology? by Burt Jordaan
The word 'cosmology' originated in Greek:
'cosmologia', meaning order, orderly arrangement or ornaments, plus the word
'logos', meaning word, reason or plan. Cosmology is the study of the Universe at
large, which has a long history, involving at least three main regimes:
religion, philosophy and science. This article deals mainly with scientific
cosmology.
Scientific Cosmology
Also called physical cosmology, it
is the branch of science that deals with the scientific study of the origins and
evolution of the Universe and the nature of the Universe on its very largest
scales.
In its earliest form (2nd century BC) physical cosmology was
basically just celestial mechanics, the study of the 'heavens'. The Greek
philosophers Aristarchus of Samos, Aristotle and Ptolemy proposed different
theories for how the heavens work.
In particular, the 'earth-centric'
Ptolemaic system was the accepted theory to explain the motion of the heavenly
bodies until Copernicus, Kepler and Galileo proposed a 'sun-centric' system in
the 16th century post by haiyan701.
Although Greek, Indian and Muslim
academics formulated the sun-centric theory centuries before Copernicus, his
reiteration that the Sun, rather than the Earth, is at the center of the solar
system is considered among the most important landmarks in the history of modern
astronomy.
Newton's Cosmology
With Isaac Newton's 1687 publication
of 'Principia Mathematica', the problem of the motion of the heavenly bodies was
solved. Newton provided a physical mechanism for Kepler's laws of planetary
motion. His law of universal gravitation resolved the anomalies caused by
gravitational interaction between the planets in the previous
systems.
Despite the words 'universal gravitation', Newton did not
consider the implications of his theory on the Universe at large, although it
implied that gravity works the same everywhere. The universal application of
gravity was left to Albert Einstein, who formulated it more than two centuries
later.
Einstein's Cosmology
Scientific cosmology really began in
1917, when Albert Einstein's published the final modification to his theory of
gravity in the paper 'Cosmological Considerations of the General Theory of
Relativity'. This paper prompted early cosmologists such as Willem de Sitter,
Karl Schwarzschild and Arthur Eddington to explore the astronomical consequences
of the theory of relativity.
Mount Wilson astronomer Harlow Shapley
championed the model of a cosmos made up of the Milky Way star system only � a
static unchanging universe. Einstein also believed this and 'fudged' his
equations of general relativity to represent this static state. He introduced a
'cosmological constant' that prevented the universe from contracting or
expanding, which was what his original equations told him.
Heber D.
Curtis, on the other hand, suggested that the observed spiral nebulae were star
systems in their own right, or 'island universes'. In 1923-24 Edwin Hubble
detected novae in the Andromeda galaxy and then showed its distance to be way
beyond the Milky Way's boundaries. This settled the debate and it was accepted
that the Milky Way was not all the universe there is. However, the cosmos was
still thought to be static and unchanging Charlotte Olympia.
Modern
Cosmology
Subsequent modeling of the universe explored the possibility
that the cosmological constant introduced by Einstein may result in an expanding
universe, depending on its value. In 1929, Edwin Hubble's discovered the red
shift of the light of distant galaxies, indicating that they move away from the
Milky Way. Hence, the universe must be expanding.
Einstein promptly
repudiated his earlier 'fudge factor' and declared that the introduction of the
cosmological constant was the "biggest blunder of his scientific career". His
original 1917 equations support an expanding universe without the cosmological
constant anyway.
In 1931 Georges Lemaitre, a Belgian priest, postulated
that an expanding universe meant a creation event at some time in the past. He
postulated that the Universe was created from a small 'cosmic egg' and set into
motion, expanding until today. This theory was later labeled the 'big
bang'.
There were many rival theories to the big bang. The 1964 discovery
of the cosmic microwave background radiation by Arno Penzias and Robert Woodrow
Wilson was a first step in ruling out many alternative physical
cosmologies.
The Golden Age of Cosmology
Recent observations made
by the COBE and WMAP satellites observing and accurately measuring this
background radiation have effectively, transformed cosmology from a highly
speculative science into a predictive science. This has led many to refer to
modern times as the "golden age of cosmology".
Present observations match
predictions made by a theory called Cosmic Inflation, first proposed by American
physicist and cosmologist Alan Guth in 1981. It is a modification of the
standard big bang theory that explains how the universe obtained the expansion
and solves some problem areas of the big bang satisfactorily.
Today a lot
can be scientifically explained, but it is still not possible to technically
explain how the universe came forth 'out of nothing' Charlotte Olympia Kitty Flats.
Modern cosmological research mainly concentrates on 'quantum cosmology',
striving to reconcile general relativity with quantum physics. This may provide
a scientific answer to this ultimate puzzle that we call 'the
Universe'.
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