The fine-tuning argument

I listened to the latest Infidel Guy podcast earlier. This was "an atheist debater's primer" i.e. it discussed several subjects which commonly come up in Christian / Atheist debates, and offered arguments for atheists to use in such situations. Like the way Jehovah's Witnesses are primed with answers to common questions, but in reverse.

One of the arguments that they discussed was the 'fine-tuning argument' - this is used by some Christians in an attempt to demonstrate that life is so unlikely that it couldn't have happened by chance.

The basic reasoning goes like this: if the way this universe works was different by the tiniest margin, then life could not exist. Therefore the universe must have been designed, because it works so well. For example, if the universal gravitational constant was slightly less, the universe would have simply expanded so fast that no planets could have formed. And many other 'constants' are found such that minor variations in them would lead to an untenable situation for life to exist.

The two main arguments against this were:

1. The universe appears to be fine-tuned to produce life, but it also appears more fine-tuned to produce black holes. Some scientists estimate there are more black holes out there than there are living organisms on this planet...

2. Existence may have had a near infinite amount of time to try out all the possible combinations of fundamental constants - perhaps there have been countless universes where the constants were totally wrong for producing life, but nobody was there to observe them. We are only here to observe the universe because the fundamental constants that work in this universe are the ones which do work together to allow life to exist. Thus all arguments to probability fall apart.

This set me thinking. Given an infinite amount of (for lack of a better word) time, then all possible universes will exist at one time or another. The universe where there is a big bang that leads to life evolving on the third planet out from a small yellow sun will happen at some point. But, using this reasoning it is also reasonable to assume that the universe where there is a God who can create a small yellow sun and start life on the third planet out from it will also happen. It is neither more likely nor less likely; given an infinity of existence, both will happen at some point.

How can you tell which you are living in?