THE BEGINNING AND THE COSMIC
EVOLUTION ( Page 2) |
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| Over and above the stars and galaxies previously known,
there came into the field of man’s vision new and weird characters
like, white dwarfs, red giants, quasars, black holes and supernovae.
Some quasars are found as far as 12 billion light years away. The
telescopes were not only looking far into space, but also back into
the distant past. As light travels at 300 000 km per second, when
we look at the nearest star we are seeing it as it was 4.6 years ago.
This is because it is 4.6 light years away from us. When we look at
a quasar 12 billion light years away we are seeing it as it was 12
billion years ago. Cosmology was becoming more complex and incomprehensible.
The more we discover and learn, the less we seem to understand the
essence of the cosmos. |
| The knowledge that the universe is expanding brought
back the question of its origin. If it is expanding, where, when and
how did the expansion start? The galaxies seem to be running away
from each other like fragments from an explosion. Some explosion!
Here came the great step in cosmology - the idea of the Big Bang origin.
Though many other theories came up to challenge the Big Bang theory,
it had survived for the last fifty years as the only sensible cosmic
view. |
| According to the Big Bang theory of the fifties and
sixties, the universe began some 15 billion years ago, as a primordial
egg. (Sounds like Hindu mythology?). A Big Bang sent the fragments
of this, far out into space and these began to develop into galaxies
and stars. Today it sounds too farfetched even for scientists. It
is, and always will be, beyond the scope of science and scientists
to answer the questions, how and why, of the origin. It comes within
the realm of philosophers and theologians and, may be, poets and prophets.
To the question, where did the big bang event take place, the answer
seemed quite simple. ‘It began at the centre of the universe’.
But now we learn that it is not like that at all. The Big Bang did
not take place at any point in space. Before the Big Bang there was
no space at all. The event that started all this was the creation,
not only of matter but also of space and time. The conclusions that
the scientists make on the origin of the universe or its evolution
keeps changing with new discoveries or findings at the last count
(February 2003), the Big-Bang origin took place between 13 and 14
billion years ago. The explosion or whatever did not send matter hurtling
into space but matter and space began expanding together with the
progress of time. |
| The Accelerating Universe. |
| There was no shortage of surprises for the astronomers
and theoretical physicists working on cosmology during the last 80
years. And they kept on doggedly pursuing the elusive answers to crucial
questions. The model of the expanding universe could get rid of the
cosmological constant or lambda. But there were other concerns. Taken
for granted that the galaxies and quasars and a host of others are
running apart from an initial expansion, the laws of Newton and of
Einstein dictate that they should eventually slow down, come to a
stop and may be fall back on itself in the big crunch. Whatever the
case the universe must be slowing down. |
| The astronomers of the nineties, armed with advanced
technologies like the Hubble space telescope, the very large telescopes
(VLTs) and other resources, began to look for the signs of deceleration.
Studying the red shift of supernova at various distances they could
determine the rate of expansion at various stages in cosmic evolution.
This should give conclusive evidence of the expansion slowing down,
of deceleration. In the late nineties two separate teams were studying
these red shifts. The evidence they found was the opposite of what
they were looking for. Instead of slowing down, the expansion of the
universe was speeding up or accelerating. This was in 1997. |
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