Fine-tuning of the universe for life II

Part II: The case of the laws and constants of physics

In Part I we talked about the high degree of fine-tuning of the initial entropy of the universe and the cosmological constant. These are exceptional cases of extreme fine-tuning but, as we will see, are not the only ones. 

We now know that out of the 31 physical constants in our universe, between 10 and 12 of these constants exhibit significant fine-tuning!

To name just a few examples, the level of fine-tuning in the gravitational constant is 1 part in 10^35, the strong nuclear force constant is fine-tuned to 1 part in 200, and the electromagnetic force constant exhibits moderate fine-tuning of 1 part in 25.  Furthermore, the ratios of the values of different force constants also require significant fine-tuning. For example, the weak nuclear force to the strong nuclear force constant ratio had to have been set with a precision of 1 part in 10,000. If the weak force had been weaker or stronger by that small fraction, stars powered by hydrogen fusion, required for life, would not have existed. More impressively, the electromagnetic force to gravity constant ratio must be accurate to 1 part in 10^40. Were this ratio a bit lower, the gravitational attraction would be too strong compared to electromagnetism pushing nuclei apart (no long-lived stars or stable solar systems). Were this ratio a bit higher, gravitational attraction would be too weak compared to electromagnetism (no heavier elements needed for life).

The fine-tuning of these properties has puzzled physicists not only because of their extreme improbability but also because there doesn’t seem to be any necessary physical or logical reason why they have to be as they are. They could conceivably have been different without violating either the fundamental laws of physics or any necessary principle of logic or mathematics. 

In addition to the values of constants within the laws of physics, the fundamental laws themselves have specific mathematical and logical structures that could have been otherwise--that is, the laws themselves have contingent rather than logically necessary features. Yet the existence of life in the universe depends on the fundamental laws having the precise mathematical structures that they do.

*** The fine-tuning of the Universe for life is the realization that if the laws of physics were different, even just by a little bit life would not exist ***

For example, both Newton’s universal law of gravitation and Coulomb's law of electrostatic attraction describe forces that diminish with the square of the distance. Nevertheless, without violating any logical principle or more fundamental law of physics, these forces could have diminished with the cube (or higher exponent) of the distance. That would have made the forces they describe too weak to allow for the possibility of life in the universe. Conversely, these forces might just as well have diminished in a strictly linear way. That would have made them too strong to allow for life in the universe. Thus, the forces at work in the universe itself (and the mathematical laws of physics describing them) display a fine-tuning that requires explanation. Yet, clearly, no physical explanation of this structure is possible, because it is precisely physics (and its most fundamental laws) that manifest this structure and requires explanation. 

Indeed, physics does not explain itself. 

Post based on Stephen C. Meyer's Return to the God Hypothesis book, chapter 7, see resources.