Saturday 17 February 2007

Pic of the day: The conditions in this universe are just perfect for life, I hear. Well, that may be an exaggeration. But at least we are here to talk about it.

Anthropic principle non-answered

The weak or general anthropic principle states that the universe is fit for human life. From this some people deduce that we are part of some master plan, or indeed that we are the most important thing in the universe. This could well be true for other reasons, but it does not exactly follow: In fact, intelligent life has so far only been found on one small planet, our own, and even here it is recent, half-hearted and most likely temporary. In contrast, billions of galaxies each contain billions of stars busily converting hydrogen to helium. From this it would seem more reasonable to conclude that helium is the main character in the master plan that is the universe. Somehow I have never heard anyone else even voice that thought before...

In the other corner we have the standard answer which most atheists seem to feel the need to give: "If the universe did not support human life, we would not be here to talk about it." Or in other words, the anthropic principle is just stating the obvious. However, this in itself is just stating the obvious, and utterly ignoring the message behind the statement. Let me explain.

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Let's say you are into sky diving, but one day your parachute does not fold out. You fall like a stone for a mile or so, but then you hit a sequence of branches in just the right order to break your fall without resisting hard enough to crush you. You land confused but unhurt at the forest bottom. Excited, you call all your friends and tell them what happened. They all reply: "Well, if you had died you wouldn't be here to talk about it." Which is perfectly true, but also completely and utterly misses the point.

The episode does not actually prove that there is a God or even a guardian angel watching over you. As the atheist will point out, it was branches all the way down. And it is in fact natural for the smaller, thinner branches to be near the top and then gradually thicker further down. This is the way trees have been for millions of years, with nary a parachute in sight. It seems the height of self-centeredness to think that the trees were made that way for you. Rather it was just your good luck to fall where you did instead of any of a trillion other places.

The same is true in cosmology. It is the same laws of nature all the way down. It seems now that life is bound to be rare in the cosmos after all. If we lived closer to the galactic core, the density of stars would be so great that a stable solar system would not persist for long. Other suns would plunge right through the ring of planets and scatter them, or at the very least would shake down huge swarms of comets from the Oort cloud which would then bombard the planets, wiping out all higher life (if not all life). On the other hand, much further out in the spiral arm and there would not have been enough of the previous generations of stars to create the heavy elements needed for planets such as ours. And our galaxy is a pretty quiet one. Others have quasars in their center, shining as brightly as the whole galaxy. You can imagine what the radiation from those would do to life in much of the galaxy.

In short, the universe could certainly have been made a lot more conductive to life. But then again, if anyone could jump out of a plane anywhere without a parachute and land unharmed, how many would be impressed by it? About the same number who marvel that they can walk on the ground without falling through, I'd guess. (This is indeed a marvel, given that atoms consist of relatively more empty space than does the solar system. But you don't see me running around telling all my friends.)

And in the end, that is what it boils down to: Gratitude, awe, or at least a sense of wonder. Knowing how easily we might not have existed at all, inspiring us to make it worth it, to make the most out of our precarious existence while it lasts. What happens after that, is up to our Intelligent Designer, if any.

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I, for my part, believe in a Creator. But if you don't, that also seems quite reasonable. But if you don't think it is a big deal, if you can't understand the awe and the sense of wonder that drives both believers and scientists to look for a cause for all things, then you get no respect from me. After all, your brain is just a collection of atoms, why would I listen to what comes out of it?