We’ve already made note of the fact that the big bang looks a lot like the Bible’s description of the formation of the world. We’ve noted that the rate of expansion of the early universe had to be within tolerances on the order of 1 part in 1015 either way. That much more and stars wouldn’t have formed; that much less and everything would have collapsed by now. In the last post we saw the asymmetry between matter and antimatter necessary for the stars and galaxies to form and that that asymmetry is on the order of one part in 109. As they say in TV commercials, “but wait! There’s more.”
If the asymmetry between matter and antimatter had been smaller, say one part in 1011 there wouldn’t have been enough matter for galaxies to form. And if it had been greater, on the order of one part in 108 the abundant matter would have congealed into enormous lumps without forming discrete stars.
The same surprises exist in the world of particle physics. If the strong force that binds atomic nuclei together were a few percentage points greater quarks wouldn’t form protons. If it were five percent weaker stars couldn’t make heavy elements past hydrogen. If the weak force was much stronger the big bang would have cooked atoms all the way up to iron, leaving no lighter elements. If gravity was stronger stars would be mostly weak red dwarfs; much weaker and they would be fast-burning blue giants. Either way so-called normal stars like our Sun would be non-existent or rare.
Many have seized on these incredibly improbable coincidences as evidence that some “Cosmic Designer” is at work. It is ironic that cosmology and physics can be conscripted to give evidence of a creator. This notion that the Goldilocks universe in which we live didn’t happen by chance is called the Anthropic Principle. The Anthropic Principle can be expressed many ways but the most common is, “the universe is the way it is because we are here to see it. If it weren’t the way it is, we wouldn’t be here.” This is reminiscent of Rene Descartes statement Je pense, donc je suis (I think, therefore I am, or cogito ergo sum in Latin). Descartes, a French philosopher of the 17th Century, set out to develop a set of fundamental principles that one can know without any doubt. As a starting point he had to prove his own existence. This he did by concluding that because he thinks, he exists. “The simple meaning of the phrase,” he wrote, “is that if one is skeptical of existence, that is in and of itself proof he does exist.” Similarly, the universe exists as it does because we are here to question its existence.
Does all of this mean there is someone or something behind the big bang? Consider this hypothetical. You have been sentenced to death by a firing squad of 100 trained sharpshooters. You stand blindfolded and hear “ready, aim, FIRE” followed by a volley of shots. Suddenly you realize you are not dead. Under these circumstances the law says you may go free. Is it not realistic to see a higher power behind this? Aren’t the odds against all 100 sharpshooters missing you so astronomical as to be impossible in the absence of divine intervention?
On the other hand, the odds of a bridge player being dealt a particular hand are something like one in six billion. Does the bridge player marvel at the hand she has been dealt or does she simply play the hand she has? Most bridge players play the hand they are dealt rather than wonder why they got that particular hand, since all hands are equally likely.
Many scientists have taken the latter position — that the universe just happened this way. But to bolster their position against the “astronomical odds” argument, they suggest that one view of reality is that there is an enormous number of existing universes, on the order of 10500 (1 followed by 500 zeroes). With so many universes it is virtually certain that one of those is suitable for life. Therefore the Anthropic Principle holds true: the universe is this way because we are here to see it. We need not wonder at this particular state any more than we wonder at any other state. By making the universe non-unique in the sense that this is not the only one there is, the need for a creator is eliminated and replaced by simple laws of probability.
So where did these 10500 universes come from? For that we need to enter the world of string theory.