The Universe has no
edge and nothing exists beyond it, not even space. In the vastness of the
Universe, the Earth, the Sun and planets are tiny dots. The Sun is merely one
star in a galaxy comprising 100,000 million stars. At least as many thousands
of million of other galaxies, each with its own star system, extend as far as
the largest and most sophisticated of optical and radio telescopes can reach.
As the Universe expands, all galaxies
and clusters of galaxies move apart from each other at speeds that depend upon
their distances. The each other at speeds that depend upon their distances. The
furthest ordinary galaxy yet detected, Abell 1835 IR is 13,230 million light
years away and is receding at 45 per cent of the speed of light. The most
distant object in the Universe as on 14 July 2004 is in background of Abell
2218. This corresponds to a distance greater than 2 billion light years. Beyond
this, astronomers are looking back to a time when the Universe was born, and
the detectable Universe fades out.
Our present view of universe began
with the findings of Copernicus, Galileo, and Newton. What they found was very
much opposed by others at the time, mainly because established order was based
on Aristotle's teachings. These "new" ideas were thought to diminish
the role of humans in the universe, to undermine our importance we have
expanded our vision since then by enormous effort, painstaking observations,
and an ongoing desire to comprehend our surroundings.
Universe theory:
The Big Bang
Theory:
According to this theory, the Universe
had its origin in a giant explosion about 18,000 million years ago. The Matter
flung out from the explosion condensed into lumps called galaxies, which are
still rushing outwards. As the Universe grows old, the matter in it thins out.
The expansion continues indefinitely. The Big Bang theory received its
strongest confirmation when 'cosmic background radiation' was discovered in
1964 by Amo Penzias and Robert Wilson, who won the Nobel Prize for this
discovery. In 2003, NASA's Wilkinson Microwave Antisotropy Probe made
measurements of the temperature of this 'cosmic microwave background' radiation
to within millionth of a degree. From these measurements scientists were able
to deduce that our universe is 13.7 billion years old and that first generation
stars began to form a mere 200 million years after the Big Bang.
Inflation Theory:
Immediately following the Big Bang,
the universe likely began a period of exaggerated outward expansion, with
matter flying outward faster than the current speed of light. This is the
inflation theory, widely accepted in the astrophysics community.
The Oscillating
Universe Theory:
This theory, a variation of the Big
Bang Theory, suggests that expansion of the Universe will eventually slow down
and stop, followed by contraction of the galaxies into another Big Bang. The
Universe, therefore, continues in endless cycles of expansion and contraction;
the laws of nature may differ in each cycle.
The Steady State
Theory:
An alternative view to the Big Bang
Theory, this theory says that Universe never originated at any one instant, nor
will it ever die. According to this theory, as the Universe expands new matter
is created to fill the space left. Therefore, the appearance of the Universe
remains constant with time.
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