Is Earth a good place for life?
By MUNGAI KIHANYA
The Sunday Nation
Nairobi,
22 April 2018
After 15 years of
writing this column, I was bound to make a blunder. Last week’s article
was a re-run of the piece I wrote in in
the World of Figures in October 2005! I was revisiting the question
of life in the universe from a different angle and I needed to refer
back to 2005 article in order to avoid repeating myself. Unfortunately,
I sent the older article by mistake!
This is the second
time that I have done this kind of mistake: The first repeat happened in
April 2010; the current one in April 2018: so, can we expect another
blunder in April 2021?
Well; this is what I
wanted to say last week…
It is
difficult to understand
why there is
any life on Earth.
Think about it:
Our kind of life
depends oxygen
(animals) and carbon dioxide (plants).
But these are quite rare on this planet.
The largest component in our atmosphere is
nitrogen (78 percent). Oxygen is just 21 per cent while carbon dioxide
is a mere four hundredths of a per cent! That is, 4 parts out of 10,000.
Why, then, is
there life on earth yet the two most crucial ingredients for it are so
rare on this planet? I have no answer…
But that leads me to
suspect that there must be life elsewhere. In fact, I wouldn’t be
surprised to find other humans -exactly like us!
400 years ago, people assumed that the Earth
was
a special place – the centre of everything.
Those who did
not subscribe to this belief were punished
heavily. Galileo
Galilei was put under house arrest for life in
1663 for saying that the sun was at the centre of the solar system. He
was only pardoned in 1992 – 329 years later!
Since then, astronomers have discovered that the
we are
actually not the centre of anything.
We are
not at the centre of the solar system; the sun is not
at the centre of the galaxy; and the galaxy is not at the centre of its local group;
and so on and so forth.
Consequently,
when
astronomers
discovered
that all the galaxies appear to be accelerating away from ours,
they
were careful
not to repeat
the mistakes of the past: making the assumption
that we are at the centre of the universe.
Now the universe
started taking its current form some 13.7 billion years ago. Our sun was
formed about 7 billion years afterwards and the earth “only” 60 million
years after the sun.
It took another 700
million years from the formation of our planet for the first life-forms
to start appearing on earth. Humans started appearing just 200,000 years
ago.
Looking at the
immense amount of time that has been available and the estimated large
number of life-supporting planets (1.5 billion) out there, I am
convinced that there aught to be other human-like life else where in the
universe. Otherwise, it would be quite a large waste of space!
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