I found this in one of my course books. It's quite interesting, added to a chapter dealing with dynamics of Friedman-Robertson-Walker universes. It looks to me like this man doesn't deny the possibility of a diety, and he is a respected scientist, no creation-pseudo-nonsens-scientist. I find it very compeling. What are your thoughs?
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THE ANTHROPIC PRINCIPLE
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It would be reassuring if one could believe that our universe (which seems destined either to recollapse and suffer a fiery death, or else to expand indefinitely and suffer a freezing death) is not the sum-total of all physical existence. A philosophically persuasive line of argumentation has, in fact, led some modern cosmologists to posit the existence of infinitely many alternative universes, all with different initial conditions. For them that seems to be the only way out of a profound puzzle: why is our universe favorable to human existence? The number of lucky 'coincidences' required to produce an environment in which life as we know it is possible, seems to defy the laws of chance.
Let us begin with the big bang. A slightly lower initial expansion rate, or higher density, or higher constant of gravity, would have made the universe recollapse and reheat before it had time to cool sufficiently to make life possible. A slightly higher expansion rate, or lower gravitational constant, would have thinned the matter too fast for galaxies to condense. It takes billions of years to cook up and distribute the basic building blocks of life (carbon, oxygen, and nitrogen) in the only suitable furnaces, the interiors of stars. A life-supporting universe must get to be at least that old, and it's laws must permit the process. For example, it is 'lucky' that the nuclear force is not quite strong enough to allow the formation of 'diprotons' (proton + proton), a process that would have quickly used up all primordial hydrogen and so deprived the stars of their fuel, and life of one of its bases. Yet that force is just strong enough to favor the formation of deuterons (proton + neutron), without which higher nucleosynthesis cannot proceed. Without a 'lucky' energy level in the carbon nucleus the formation of carbon out of helium (3H4 ? C12 + 2?) would have failed. But equally luckily, the oxygen nucleus has an energy level that prevents the reaction C12 + H4 ? O16, which would have depleted the carbon as soon as it was formed.
Examples of this kind abound in all branches of science. Here we shall mention only two others. One from biology: apparently the whole basis of life (DNA) would be in jeopardy if the charge or mass of the electron were only slightly different from what they are. And an example from ecology: water possesses the rare yet vital property that its solid form (ice) is lighter than its liquid form. As a consequence, lakes freeze over in winter and the ice protects the life below, possibly even emerging life. Were in otherwise, more and more ice would grow from the bottom upwards without being melted in the summers, until lakes and oceans were frozen solid.
Can all these 'lucky' coincidences be due to pure chance? The law that multiplies probabilities makes this highly unlikely. One can perhaps hope for the eventual discovery of a 'Theory of Everything' - a theory that fixes all the laws and constants of Nature and shows our universe to be unique. But the mystery would remain: why does the only possible universe permit life? One supposition that cannot be disproved is that a benevolent deity so designed the world. But it is part of the credo of modern science not to invoke a deity to explain physical facts. (Newton did not yet feel that so strongly, he believed God would have to intervene periodically to adjust the planetary orbits, since it seemed to him that the mutual gravity of he planets lead to instabilities. It took a hundred years before Laplace was able to solve the stability problem the modern way.) Out of all these difficulties grew the anthropic principle: if there are infinitely many alterative universes, then there is no mystery in finding ourselves in one that permits our presence.
Quoted from: Relativity - special, general and cosmological, Wolfgang Rindler