Fine Tuning Argument
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[edit] Definition
The Fine Tuning Argument is the proposition that certain relationships between physical constants seem "fine tuned" for the universe to produce and sustain life; and that therefore this is evidence of an intelligence (i.e. God) selecting the physical constants.
Examples of constants claimed to be fine tuned include the strength of the strong nuclear force and weak nuclear force relative to other forces; the ratio of the mass of the proton to the electron; the strength of the electromagnetic coupling constant; the strength of the gravitational force relative to the electromagnetic force; the resonance levels of beryllium in the triple alpha process; and others.
[edit] Discussion
Each particular claim of fine tuning must be examined on its own merits. However, there are some comments that may be made about this class of argument in general.
[edit] Incompatibility with other creationist arguments
The fine tuning argument is incompatible with many other creationist arguments, which depend on the proposition that a miracle, or set of miracles, was necessary to produce a habitat for life and life itself.
The fine tuning argument, by contrast, asserts that the laws of nature are sufficient to explain such things, that slightly different laws of nature would not be sufficient, and that this is evidence that the laws of nature were designed.
This distinction is not appreciated by all creationists. We have, for example, seen a pamphlet which appeals to the fine tuning argument on one page, and on the next asserts that the laws of physics make the formation of stars (including our sun) impossible; and that the existence of the sun is therefore evidence of a miracle. But if there is a law of physics preventing stellar formation, then the universe is certainly not fine-tuned to be congenial to life.
[edit] "Not as we know it"
Arguments for fine tuning usually focus on the conditions necessary to produce our sort of life. Arguably, this is the wrong calculation to make. If universes with other physical constants permit the existence of "life, but not as we know it", then the fact that we are alive does not require fine-tuning; and the fact that we are life in this particular form, however unlikely, might then be legitimately regarded as the luck of the draw.
For example, it is undoubtedly true that changing the electromagnetic coupling constant would make our own particular biochemistry impossible; but what else might it make possible? As no-one is in a position to work out the alternative biology possible in universes other than our own, this point, and therefore the validity of the fine tuning argument, is moot.
[edit] Unknown relationships between constants
Unless we know the causes that underlie the relationships between constants, any appearance of fine tuning may be deceptive.
To take an example where we do know the causal factors, it is very convenient that we should all find ourselves at the altitude we do. To be only a few yards higher up or lower down would be fatal: in the first case I'd break my neck, in the second case I'd suffocate. Relative to the radius of the Earth, our altitude is fine tuned to within 0.1% of sea level (astronauts excepted). My feet are at the level of my carpet to the nearest micron --- how about that! And yet we don't see this either as an example of fine-tuning by a hidden hand, nor of a fortunate coincidence, because we are aware of the underlying causal factors that brought this happy state of affairs about.
In particle physics, we are not yet aware of the underlying causes that determine the relationships between the physical constants, and so we can't say whether a supposed example of fine tuning might in fact be an example of an analogous situation.
[edit] Difficulties of calculating probabilities
What we would wish to know is how probable the existence of a life-friendly universe is. But those who support the fine tuning argument can't actually make that calculation. This is not their fault: we simply do not have the knowledge required. To make the calculation, we should have to know the ensemble of possible universes, and to calculate what proportion of them might contain life.
Under these circumstances, the numbers produced by advocates of the fine tuning argument are almost irrelevant. To say that the relationship between two constants is fine tuned to within 1% sounds most impressive at first. But then when one exclaims to oneself, "Hey, what are the odds of that!" one realizes that one has no idea. Perhaps it was a certainty. Again, the fine tuning argument runs into difficulties because we do not know the causes which underlie the values of the constants.
[edit] Multiverses and the Inflationary Hypothesis
According to one promising concept in cosmology, the Inflationary Hypothesis, the Big Bang would have resulted in the creation of many different universes, unable to communicate with one another (because of the impossibility of sending information faster than light) and, for this reason, having different physical laws. In that case, there is no question of fine tuning: we just happen to live in one of the universes which is congenial to life.
It should be emphasized that these multiple universes were not, as some creationists claim, produced ad hoc to deal with the problem of fine tuning: rather, they are an inevitable corollary of the Inflationary Hypothesis.
[edit] Appeals to the Anthropic Principle
The Anthropic Principle is the observation that any observers wondering about the origins of the universe must necessarily live in a universe congenial to life, and that therefore it is foolish to puzzle over the likelihood of such an event.
There is considerable debate over whether the Anthropic Principle is (a) insightful (b) wrong (c) completely meaningless.
