Paul Davies (noted astronomer and popular science writer) published an article today in the NYT, of which I will essay an executive summary.
We
really do not know anything about the probability of the origin of
life, given accommodating environments, because we have a sample of only
one, Earth, which tells us nothing about probability.
♦♦
♦♦
So,
recent analyses that suggest that watery worlds somewhat like Earth may
be relatively common in the Galaxy (and all other similarly situated
galaxies, which may well number in the trillions in the wider universe),
actually don't give us any information about whether life in the
universe is common, rare, or even unique to Earth.
Of
course, most scientists have a "hunch" that life is common, but the
truth is we just don't know. The origin of life is an intractable
problem; it has not yielded to experimental investigation and there is
no well-worked out a priori theory that predicts from first principles that life must evolve from non-life. Again, we just do not know, however "sure" we may feel about it.
So, what then?
To me, this is a very strong argument for the extreme importance of
searching for signs of life. There are very promising research projects
being worked on and proposed to investigate the chemical signatures of
life in the atmospheres of planets orbiting other stars. I would like to
suggest that, after research into ameliorating and correcting the
effects of climate change, including the development of renewable energy
sources and sustainable methods of food production, etc., this is the most significant scientific question of our time.
Because, and this is a critical point, as soon as we have strong evidence of a biosphere anywhere other
than Earth, it can then be accepted as a near certainty that life has
originated in multiple locations in the universe; and if we find more
than one; we can even come by some kind of estimate as to just how
common it is.
Why is this important? Well, it just is. If you don't have enough of a sense of wonder to see that, I can't convince you.