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THE BEGINNING AND THE COSMIC
EVOLUTION ( Page 1 ) |
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| “Physics, beware
of Metaphysics”: Isaac Newton |
| When did all this start, and how? Was there a beginning
at all? Or was the universe always like this? A few centuries back
there were no such doubts. Everything was simple and clear. God, the
Supreme being, the Almighty, created the universe and everything in
it. In those days, the universe had at its centre the earth, with
the sun, the moon and the stars as big or small lights in the sky.
And the sky was the ceiling or vault of our world. All this changed
with the advent of modern science and technology. With new resources
at their disposal, the astronomers began to look deeper into space
for clearer pictures and physicists began to formulate new theories
on cosmology based on these findings. The wealth of new information
about space and heavenly bodies that we had acquired in the last century
is really remarkable. |
| The Static Universe |
| At the start of the twentieth century, the scientists
used the old laws of Newton and Kepler to explain the dynamics of
heavenly bodies. This model of the universe was static. The only movements
were the rotation and revolution of the planets. The universe as a
whole remained as it is. On this model of the universe, there was
no beginning and there will be no end. Hence the question of how all
this started was not relevant. This was the model on which Albert
Einstein was building his theories of relativity. His theories on
gravity were much more inclusive than those of Newton. His work encompassed
not only the fields of gravity and astronomy, it included particle
physics, nuclear energy, quantum mechanics, in fact every aspect of
physics. People call him a genius and his work is considered to be
thought-experiments. I would call him a prophet and his thought experiments
‘works of inspiration’. |
| Einstein could not understand why the universe was
static. According to him, the gravitational forces should bring the
galaxies closer and closer. The universe must be contracting. But
there was no sign of such contraction. If the universe is not contracting
it must be expanding, he argued - expanding, as if the galaxies are
hurtling out into space following an initial explosion. There was
no sign of such expansion either. Following his own dictum that imagination
should come in where knowledge is lacking, he invented an imaginary
repulsive force that exist in the empty spaces between galaxies. This
overcomes or balances the force of gravity and prevents the universe
from collapsing on itself in a big crunch. In his equations he termed
this quantity, lambda ???one of the letters of the Greek alphabet.
Later it was called the cosmological constant. His equations also
included another quantity represented by another Greek letter ? omega,
which decided the shape of the universe. Experimental evidences for
most of his theories were to be obtained, one after another, during
the ensuing decades, some even after his death. |
| The Expanding Universe |
| Einstein published his theories in 1917, complete with
lambda, omega and all. Then in 1929, Edwin Hubble noticed a considerable
red shift in the radiations from a very distant galaxy. This red shift
indicated that the galaxy was receding from us rather fast. Hubble
and others observed the same kind of red shift in the light from distant
galaxies from every corner of the universe. This proved conclusively
that the universe is expanding. In this model of the expanding universe,
the cosmological constant, lambda of Einstein’s equations became
irrelevant. Einstein accepted that the inclusion of lambda in his
equations was the greatest blunder of his life, as it seemed at that
time that the expanding universe could be explained without the inclusion
of the cosmological constant. |
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