Thursday, April 2, 2009

Life, the Universe and the Everything

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Paul Davies’ ‘The Fifth Miracle’ threw a spanner into Carl Sagan’s (and my) magnificent cosmic vision of a universe teeming with life. He simply asks one question- Doesn’t this vision mean that physical laws are rigged in favour of life? Is it possible that the physical laws themselves or some other ‘life’ laws that operate at a higher level are designed to make the spontaneous origin of life an inevitability? If your answer is yes, then you are a biological determinist, and you are only step away from that unutterable blasphemy called religion, and a supernaturally ordained universe. Davies espouses a school of thought I haven’t been exposed to previously. He believes that everything in the biosphere can be explained by natural selection and Darwinian evolution; but this implies that there must be a first living creature from which everything else evolved. For some scientists, the leap of reasoning required to visualize the painfully slow workings of evolution is not too different from one required to visualize the spontaneous origin of life from inorganic chemicals. Davies doesn’t agree. He claims that the probability of a primordial soup of chemicals (self) organizing themselves into something that can even satisfy the most lax definitions of life is too low. If indeed the most miniscule of miniscule probabilities was hit here on Earth, then we won some kind of once-only cosmic lottery. It won’t happen again. Time, which is conveniently used to explain the many counter-intuitive machinations of evolution, is far less useful here. Current models predict that life originated almost immediately on planet Earth, in an astronomically insignificant few hundreds of millions of years. On the other hand, evolution was given the best of four billion years to weave its magic. The point to be taken away from this argument is that life being so unlikely couldn’t have occurred more than a handful of times (or only once); if you believe otherwise, you believe that the laws of the universe are somehow rigged to favour life, and you are a biological determinist. Carl Sagan (and others), who worked so hard to eliminate any traces of supernatural trimmings from our understanding of the universe, actually implicitly champions a theistic world view!

My chief grouse with this approach concerns the conclusion that biological determinism is the only way to explain a universe full of life. I’ll illustrate with the example of galaxies. We can see the beautifully ordered structure in a spiral galaxy, and ask – Are the laws of the universe rigged to produce this? The answer is yes, simply because we can see a spiral galaxy. We know that life exists because we do, and because we know that, in some sense, the laws of the universe are rigged in favour of life. I have a solution to the problem of rarity of life. It uses a theory called panspermia which claims that terrestrial life is of extra-terrestrial origin. If panspermia is possible, (Davies believes that it is, and explains it in an engaging chapter on life shuttling back and forth between early Earth and early Mars on the back of meteorites) then life may have originated in an exceedingly small number of places in the Universe, but may have been carried to many other planets and stellar systems. Since we don’t have a fix yet on mathematical estimates for the likelihood of spontaneous chemical generation of life, the frequency could be something like once in each galaxy. Occam’s Razor lends itself to a simpler explanation, of course, if we are determined to hold on to the view that the universe is flourishing with life. The origin of life isn’t as rare an occurrence as we believe, and if the figures suggest otherwise, the figures must be wrong. There’s another caveat here. Is it possible that there is any phenomenon in the universe that is so astronomically improbable that it will occur only once? Yes, if the Universe is finitely large and has a finite life span. Then life can be one of these Special Ones. Interestingly this is an argument against biological determinism; life is just rare, not cosmically determined. There could other such phenomena, like a star system where 135 stars are held together in mutual gravitational attraction. As it is beyond our current capacity to test this uniqueness hypothesis, any differences are purely ideological.

Reading John Gribbin’s ‘Stardust’ is much more palatable for my stubbornly romantic idea of universal life. And for a while, I was actually reading both at the same time! John Gribbin fleshes out the astronomically prevalent view that we are the stuff of stars (rather obese and short lived ones, but hell), and just as surely some stars cook themselves into supernovae, life must arise. If anything, Paul Davies has ensured that I cannot satisfy myself with this cozy outlook, in the face of contrary (probabilistic) evidence. It’s possible that we are alone in the universe, and if we aren’t the others are so far away that it is improbable that we’ll meet before either of us self-destruct. Nothing, however, in the long and mostly satisfactory history of scientific endeavour suggests that we are barking up the wrong tree, and that we might need a fundamentally novel metaphysical law to explain away the existence of life. Here’s where I make a leap of faith. I predict that we will discover independent (not through pesky panspermia) extra-terrestrial life in the near future, probably in the Solar System itself. That will of course mean that the universe is full to bursting point with life, simply because we have seen so, with our ridiculously tiny observing powers. If we don’t conform to that, then we have to update our counter-theory to a much more inane one: it’s not the Earth which is unique, but the entire Solar System.